* expr.c (expand_expr): Return const0_rtx, not error_mark_node.

[gcc.git] / gcc / expr.c

/* Convert tree expression to rtl instructions, for GNU compiler.
   Copyright (C) 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000
   Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


#include "config.h"
#include "system.h"
#include "machmode.h"
#include "rtl.h"
#include "tree.h"
#include "obstack.h"
#include "flags.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "except.h"
#include "function.h"
#include "insn-flags.h"
#include "insn-codes.h"
#include "insn-config.h"
/* Include expr.h after insn-config.h so we get HAVE_conditional_move. */
#include "expr.h"
#include "recog.h"
#include "reload.h"
#include "output.h"
#include "typeclass.h"
#include "defaults.h"
#include "toplev.h"
#include "ggc.h"
#include "intl.h"
#include "tm_p.h"

#ifndef ACCUMULATE_OUTGOING_ARGS
#define ACCUMULATE_OUTGOING_ARGS 0
#endif

/* Supply a default definition for PUSH_ARGS.  */
#ifndef PUSH_ARGS
#ifdef PUSH_ROUNDING
#define PUSH_ARGS       !ACCUMULATE_OUTGOING_ARGS
#else
#define PUSH_ARGS       0
#endif
#endif

/* Decide whether a function's arguments should be processed
   from first to last or from last to first.

   They should if the stack and args grow in opposite directions, but
   only if we have push insns.  */

#ifdef PUSH_ROUNDING

#if defined (STACK_GROWS_DOWNWARD) != defined (ARGS_GROW_DOWNWARD)
#define PUSH_ARGS_REVERSED      /* If it's last to first */
#endif

#endif

#ifndef STACK_PUSH_CODE
#ifdef STACK_GROWS_DOWNWARD
#define STACK_PUSH_CODE PRE_DEC
#else
#define STACK_PUSH_CODE PRE_INC
#endif
#endif

/* Assume that case vectors are not pc-relative.  */
#ifndef CASE_VECTOR_PC_RELATIVE
#define CASE_VECTOR_PC_RELATIVE 0
#endif

/* If this is nonzero, we do not bother generating VOLATILE
   around volatile memory references, and we are willing to
   output indirect addresses.  If cse is to follow, we reject
   indirect addresses so a useful potential cse is generated;
   if it is used only once, instruction combination will produce
   the same indirect address eventually.  */
int cse_not_expected;

/* Nonzero to generate code for all the subroutines within an
   expression before generating the upper levels of the expression.
   Nowadays this is never zero.  */
int do_preexpand_calls = 1;

/* Don't check memory usage, since code is being emitted to check a memory
   usage.  Used when current_function_check_memory_usage is true, to avoid
   infinite recursion.  */
static int in_check_memory_usage;

/* Chain of pending expressions for PLACEHOLDER_EXPR to replace.  */
static tree placeholder_list = 0;

/* This structure is used by move_by_pieces to describe the move to
   be performed.  */
struct move_by_pieces
{
  rtx to;
  rtx to_addr;
  int autinc_to;
  int explicit_inc_to;
  rtx from;
  rtx from_addr;
  int autinc_from;
  int explicit_inc_from;
  unsigned HOST_WIDE_INT len;
  HOST_WIDE_INT offset;
  int reverse;
};

/* This structure is used by clear_by_pieces to describe the clear to
   be performed.  */

struct clear_by_pieces
{
  rtx to;
  rtx to_addr;
  int autinc_to;
  int explicit_inc_to;
  unsigned HOST_WIDE_INT len;
  HOST_WIDE_INT offset;
  int reverse;
};

extern struct obstack permanent_obstack;

static rtx get_push_address     PARAMS ((int));

static rtx enqueue_insn         PARAMS ((rtx, rtx));
static unsigned HOST_WIDE_INT move_by_pieces_ninsns
                                PARAMS ((unsigned HOST_WIDE_INT,
                                         unsigned int));
static void move_by_pieces_1    PARAMS ((rtx (*) (rtx, ...), enum machine_mode,
                                         struct move_by_pieces *));
static void clear_by_pieces     PARAMS ((rtx, unsigned HOST_WIDE_INT,
                                         unsigned int));
static void clear_by_pieces_1   PARAMS ((rtx (*) (rtx, ...),
                                         enum machine_mode,
                                         struct clear_by_pieces *));
static rtx get_subtarget        PARAMS ((rtx));
static int is_zeros_p           PARAMS ((tree));
static int mostly_zeros_p       PARAMS ((tree));
static void store_constructor_field PARAMS ((rtx, unsigned HOST_WIDE_INT,
                                             HOST_WIDE_INT, enum machine_mode,
                                             tree, tree, unsigned int, int));
static void store_constructor   PARAMS ((tree, rtx, unsigned int, int,
                                         HOST_WIDE_INT));
static rtx store_field          PARAMS ((rtx, HOST_WIDE_INT,
                                         HOST_WIDE_INT, enum machine_mode,
                                         tree, enum machine_mode, int,
                                         unsigned int, HOST_WIDE_INT, int));
static enum memory_use_mode
  get_memory_usage_from_modifier PARAMS ((enum expand_modifier));
static tree save_noncopied_parts PARAMS ((tree, tree));
static tree init_noncopied_parts PARAMS ((tree, tree));
static int safe_from_p          PARAMS ((rtx, tree, int));
static int fixed_type_p         PARAMS ((tree));
static rtx var_rtx              PARAMS ((tree));
static int readonly_fields_p    PARAMS ((tree));
static rtx expand_expr_unaligned PARAMS ((tree, unsigned int *));
static rtx expand_increment     PARAMS ((tree, int, int));
static void preexpand_calls     PARAMS ((tree));
static void do_jump_by_parts_greater PARAMS ((tree, int, rtx, rtx));
static void do_jump_by_parts_equality PARAMS ((tree, rtx, rtx));
static void do_compare_and_jump PARAMS ((tree, enum rtx_code, enum rtx_code,
                                         rtx, rtx));
static rtx do_store_flag        PARAMS ((tree, rtx, enum machine_mode, int));

/* Record for each mode whether we can move a register directly to or
   from an object of that mode in memory.  If we can't, we won't try
   to use that mode directly when accessing a field of that mode.  */

static char direct_load[NUM_MACHINE_MODES];
static char direct_store[NUM_MACHINE_MODES];

/* If a memory-to-memory move would take MOVE_RATIO or more simple
   move-instruction sequences, we will do a movstr or libcall instead.  */

#ifndef MOVE_RATIO
#if defined (HAVE_movstrqi) || defined (HAVE_movstrhi) || defined (HAVE_movstrsi) || defined (HAVE_movstrdi) || defined (HAVE_movstrti)
#define MOVE_RATIO 2
#else
/* If we are optimizing for space (-Os), cut down the default move ratio */
#define MOVE_RATIO (optimize_size ? 3 : 15)
#endif
#endif

/* This macro is used to determine whether move_by_pieces should be called
   to perform a structure copy. */
#ifndef MOVE_BY_PIECES_P
#define MOVE_BY_PIECES_P(SIZE, ALIGN) \
  (move_by_pieces_ninsns (SIZE, ALIGN) < MOVE_RATIO)
#endif

/* This array records the insn_code of insns to perform block moves.  */
enum insn_code movstr_optab[NUM_MACHINE_MODES];

/* This array records the insn_code of insns to perform block clears.  */
enum insn_code clrstr_optab[NUM_MACHINE_MODES];

/* SLOW_UNALIGNED_ACCESS is non-zero if unaligned accesses are very slow.  */

#ifndef SLOW_UNALIGNED_ACCESS
#define SLOW_UNALIGNED_ACCESS(MODE, ALIGN) STRICT_ALIGNMENT
#endif
\f
/* This is run once per compilation to set up which modes can be used
   directly in memory and to initialize the block move optab.  */

void
init_expr_once ()
{
  rtx insn, pat;
  enum machine_mode mode;
  int num_clobbers;
  rtx mem, mem1;
  char *free_point;

  start_sequence ();

  /* Since we are on the permanent obstack, we must be sure we save this
     spot AFTER we call start_sequence, since it will reuse the rtl it
     makes.  */
  free_point = (char *) oballoc (0);

  /* Try indexing by frame ptr and try by stack ptr.
     It is known that on the Convex the stack ptr isn't a valid index.
     With luck, one or the other is valid on any machine.  */
  mem = gen_rtx_MEM (VOIDmode, stack_pointer_rtx);
  mem1 = gen_rtx_MEM (VOIDmode, frame_pointer_rtx);

  insn = emit_insn (gen_rtx_SET (0, NULL_RTX, NULL_RTX));
  pat = PATTERN (insn);

  for (mode = VOIDmode; (int) mode < NUM_MACHINE_MODES;
       mode = (enum machine_mode) ((int) mode + 1))
    {
      int regno;
      rtx reg;

      direct_load[(int) mode] = direct_store[(int) mode] = 0;
      PUT_MODE (mem, mode);
      PUT_MODE (mem1, mode);

      /* See if there is some register that can be used in this mode and
         directly loaded or stored from memory.  */

      if (mode != VOIDmode && mode != BLKmode)
        for (regno = 0; regno < FIRST_PSEUDO_REGISTER
             && (direct_load[(int) mode] == 0 || direct_store[(int) mode] == 0);
             regno++)
          {
            if (! HARD_REGNO_MODE_OK (regno, mode))
              continue;

            reg = gen_rtx_REG (mode, regno);

            SET_SRC (pat) = mem;
            SET_DEST (pat) = reg;
            if (recog (pat, insn, &num_clobbers) >= 0)
              direct_load[(int) mode] = 1;

            SET_SRC (pat) = mem1;
            SET_DEST (pat) = reg;
            if (recog (pat, insn, &num_clobbers) >= 0)
              direct_load[(int) mode] = 1;

            SET_SRC (pat) = reg;
            SET_DEST (pat) = mem;
            if (recog (pat, insn, &num_clobbers) >= 0)
              direct_store[(int) mode] = 1;

            SET_SRC (pat) = reg;
            SET_DEST (pat) = mem1;
            if (recog (pat, insn, &num_clobbers) >= 0)
              direct_store[(int) mode] = 1;
          }
    }

  end_sequence ();
  obfree (free_point);
}

/* This is run at the start of compiling a function.  */

void
init_expr ()
{
  cfun->expr = (struct expr_status *) xmalloc (sizeof (struct expr_status));

  pending_chain = 0;
  pending_stack_adjust = 0;
  stack_pointer_delta = 0;
  inhibit_defer_pop = 0;
  saveregs_value = 0;
  apply_args_value = 0;
  forced_labels = 0;
}

void
mark_expr_status (p)
     struct expr_status *p;
{
  if (p == NULL)
    return;

  ggc_mark_rtx (p->x_saveregs_value);
  ggc_mark_rtx (p->x_apply_args_value);
  ggc_mark_rtx (p->x_forced_labels);
}

void
free_expr_status (f)
     struct function *f;
{
  free (f->expr);
  f->expr = NULL;
}

/* Small sanity check that the queue is empty at the end of a function.  */

void
finish_expr_for_function ()
{
  if (pending_chain)
    abort ();
}
\f
/* Manage the queue of increment instructions to be output
   for POSTINCREMENT_EXPR expressions, etc.  */

/* Queue up to increment (or change) VAR later.  BODY says how:
   BODY should be the same thing you would pass to emit_insn
   to increment right away.  It will go to emit_insn later on.

   The value is a QUEUED expression to be used in place of VAR
   where you want to guarantee the pre-incrementation value of VAR.  */

static rtx
enqueue_insn (var, body)
     rtx var, body;
{
  pending_chain = gen_rtx_QUEUED (GET_MODE (var), var, NULL_RTX, NULL_RTX,
                                  body, pending_chain);
  return pending_chain;
}

/* Use protect_from_queue to convert a QUEUED expression
   into something that you can put immediately into an instruction.
   If the queued incrementation has not happened yet,
   protect_from_queue returns the variable itself.
   If the incrementation has happened, protect_from_queue returns a temp
   that contains a copy of the old value of the variable.

   Any time an rtx which might possibly be a QUEUED is to be put
   into an instruction, it must be passed through protect_from_queue first.
   QUEUED expressions are not meaningful in instructions.

   Do not pass a value through protect_from_queue and then hold
   on to it for a while before putting it in an instruction!
   If the queue is flushed in between, incorrect code will result.  */

rtx
protect_from_queue (x, modify)
     register rtx x;
     int modify;
{
  register RTX_CODE code = GET_CODE (x);

#if 0  /* A QUEUED can hang around after the queue is forced out.  */
  /* Shortcut for most common case.  */
  if (pending_chain == 0)
    return x;
#endif

  if (code != QUEUED)
    {
      /* A special hack for read access to (MEM (QUEUED ...)) to facilitate
         use of autoincrement.  Make a copy of the contents of the memory
         location rather than a copy of the address, but not if the value is
         of mode BLKmode.  Don't modify X in place since it might be
         shared.  */
      if (code == MEM && GET_MODE (x) != BLKmode
          && GET_CODE (XEXP (x, 0)) == QUEUED && !modify)
        {
          register rtx y = XEXP (x, 0);
          register rtx new = gen_rtx_MEM (GET_MODE (x), QUEUED_VAR (y));

          MEM_COPY_ATTRIBUTES (new, x);

          if (QUEUED_INSN (y))
            {
              register rtx temp = gen_reg_rtx (GET_MODE (new));
              emit_insn_before (gen_move_insn (temp, new),
                                QUEUED_INSN (y));
              return temp;
            }
          return new;
        }
      /* Otherwise, recursively protect the subexpressions of all
         the kinds of rtx's that can contain a QUEUED.  */
      if (code == MEM)
        {
          rtx tem = protect_from_queue (XEXP (x, 0), 0);
          if (tem != XEXP (x, 0))
            {
              x = copy_rtx (x);
              XEXP (x, 0) = tem;
            }
        }
      else if (code == PLUS || code == MULT)
        {
          rtx new0 = protect_from_queue (XEXP (x, 0), 0);
          rtx new1 = protect_from_queue (XEXP (x, 1), 0);
          if (new0 != XEXP (x, 0) || new1 != XEXP (x, 1))
            {
              x = copy_rtx (x);
              XEXP (x, 0) = new0;
              XEXP (x, 1) = new1;
            }
        }
      return x;
    }
  /* If the increment has not happened, use the variable itself.  */
  if (QUEUED_INSN (x) == 0)
    return QUEUED_VAR (x);
  /* If the increment has happened and a pre-increment copy exists,
     use that copy.  */
  if (QUEUED_COPY (x) != 0)
    return QUEUED_COPY (x);
  /* The increment has happened but we haven't set up a pre-increment copy.
     Set one up now, and use it.  */
  QUEUED_COPY (x) = gen_reg_rtx (GET_MODE (QUEUED_VAR (x)));
  emit_insn_before (gen_move_insn (QUEUED_COPY (x), QUEUED_VAR (x)),
                    QUEUED_INSN (x));
  return QUEUED_COPY (x);
}

/* Return nonzero if X contains a QUEUED expression:
   if it contains anything that will be altered by a queued increment.
   We handle only combinations of MEM, PLUS, MINUS and MULT operators
   since memory addresses generally contain only those.  */

int
queued_subexp_p (x)
     rtx x;
{
  register enum rtx_code code = GET_CODE (x);
  switch (code)
    {
    case QUEUED:
      return 1;
    case MEM:
      return queued_subexp_p (XEXP (x, 0));
    case MULT:
    case PLUS:
    case MINUS:
      return (queued_subexp_p (XEXP (x, 0))
              || queued_subexp_p (XEXP (x, 1)));
    default:
      return 0;
    }
}

/* Perform all the pending incrementations.  */

void
emit_queue ()
{
  register rtx p;
  while ((p = pending_chain))
    {
      rtx body = QUEUED_BODY (p);

      if (GET_CODE (body) == SEQUENCE)
        {
          QUEUED_INSN (p) = XVECEXP (QUEUED_BODY (p), 0, 0);
          emit_insn (QUEUED_BODY (p));
        }
      else
        QUEUED_INSN (p) = emit_insn (QUEUED_BODY (p));
      pending_chain = QUEUED_NEXT (p);
    }
}
\f
/* Copy data from FROM to TO, where the machine modes are not the same.
   Both modes may be integer, or both may be floating.
   UNSIGNEDP should be nonzero if FROM is an unsigned type.
   This causes zero-extension instead of sign-extension.  */

void
convert_move (to, from, unsignedp)
     register rtx to, from;
     int unsignedp;
{
  enum machine_mode to_mode = GET_MODE (to);
  enum machine_mode from_mode = GET_MODE (from);
  int to_real = GET_MODE_CLASS (to_mode) == MODE_FLOAT;
  int from_real = GET_MODE_CLASS (from_mode) == MODE_FLOAT;
  enum insn_code code;
  rtx libcall;

  /* rtx code for making an equivalent value.  */
  enum rtx_code equiv_code = (unsignedp ? ZERO_EXTEND : SIGN_EXTEND);

  to = protect_from_queue (to, 1);
  from = protect_from_queue (from, 0);

  if (to_real != from_real)
    abort ();

  /* If FROM is a SUBREG that indicates that we have already done at least
     the required extension, strip it.  We don't handle such SUBREGs as
     TO here.  */

  if (GET_CODE (from) == SUBREG && SUBREG_PROMOTED_VAR_P (from)
      && (GET_MODE_SIZE (GET_MODE (SUBREG_REG (from)))
          >= GET_MODE_SIZE (to_mode))
      && SUBREG_PROMOTED_UNSIGNED_P (from) == unsignedp)
    from = gen_lowpart (to_mode, from), from_mode = to_mode;

  if (GET_CODE (to) == SUBREG && SUBREG_PROMOTED_VAR_P (to))
    abort ();

  if (to_mode == from_mode
      || (from_mode == VOIDmode && CONSTANT_P (from)))
    {
      emit_move_insn (to, from);
      return;
    }

  if (VECTOR_MODE_P (to_mode) || VECTOR_MODE_P (from_mode))
    {
      if (GET_MODE_BITSIZE (from_mode) != GET_MODE_BITSIZE (to_mode))
        abort ();
      
      if (VECTOR_MODE_P (to_mode))
        from = gen_rtx_SUBREG (to_mode, from, 0);
      else
        to = gen_rtx_SUBREG (from_mode, to, 0);

      emit_move_insn (to, from);
      return;
    }

  if (to_real != from_real)
    abort ();

  if (to_real)
    {
      rtx value;

      if (GET_MODE_BITSIZE (from_mode) < GET_MODE_BITSIZE (to_mode))
        {
          /* Try converting directly if the insn is supported.  */
          if ((code = can_extend_p (to_mode, from_mode, 0))
              != CODE_FOR_nothing)
            {
              emit_unop_insn (code, to, from, UNKNOWN);
              return;
            }
        }
 
#ifdef HAVE_trunchfqf2
      if (HAVE_trunchfqf2 && from_mode == HFmode && to_mode == QFmode)
        {
          emit_unop_insn (CODE_FOR_trunchfqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_trunctqfqf2
      if (HAVE_trunctqfqf2 && from_mode == TQFmode && to_mode == QFmode)
        {
          emit_unop_insn (CODE_FOR_trunctqfqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncsfqf2
      if (HAVE_truncsfqf2 && from_mode == SFmode && to_mode == QFmode)
        {
          emit_unop_insn (CODE_FOR_truncsfqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncdfqf2
      if (HAVE_truncdfqf2 && from_mode == DFmode && to_mode == QFmode)
        {
          emit_unop_insn (CODE_FOR_truncdfqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncxfqf2
      if (HAVE_truncxfqf2 && from_mode == XFmode && to_mode == QFmode)
        {
          emit_unop_insn (CODE_FOR_truncxfqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_trunctfqf2
      if (HAVE_trunctfqf2 && from_mode == TFmode && to_mode == QFmode)
        {
          emit_unop_insn (CODE_FOR_trunctfqf2, to, from, UNKNOWN);
          return;
        }
#endif

#ifdef HAVE_trunctqfhf2
      if (HAVE_trunctqfhf2 && from_mode == TQFmode && to_mode == HFmode)
        {
          emit_unop_insn (CODE_FOR_trunctqfhf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncsfhf2
      if (HAVE_truncsfhf2 && from_mode == SFmode && to_mode == HFmode)
        {
          emit_unop_insn (CODE_FOR_truncsfhf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncdfhf2
      if (HAVE_truncdfhf2 && from_mode == DFmode && to_mode == HFmode)
        {
          emit_unop_insn (CODE_FOR_truncdfhf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncxfhf2
      if (HAVE_truncxfhf2 && from_mode == XFmode && to_mode == HFmode)
        {
          emit_unop_insn (CODE_FOR_truncxfhf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_trunctfhf2
      if (HAVE_trunctfhf2 && from_mode == TFmode && to_mode == HFmode)
        {
          emit_unop_insn (CODE_FOR_trunctfhf2, to, from, UNKNOWN);
          return;
        }
#endif

#ifdef HAVE_truncsftqf2
      if (HAVE_truncsftqf2 && from_mode == SFmode && to_mode == TQFmode)
        {
          emit_unop_insn (CODE_FOR_truncsftqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncdftqf2
      if (HAVE_truncdftqf2 && from_mode == DFmode && to_mode == TQFmode)
        {
          emit_unop_insn (CODE_FOR_truncdftqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncxftqf2
      if (HAVE_truncxftqf2 && from_mode == XFmode && to_mode == TQFmode)
        {
          emit_unop_insn (CODE_FOR_truncxftqf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_trunctftqf2
      if (HAVE_trunctftqf2 && from_mode == TFmode && to_mode == TQFmode)
        {
          emit_unop_insn (CODE_FOR_trunctftqf2, to, from, UNKNOWN);
          return;
        }
#endif

#ifdef HAVE_truncdfsf2
      if (HAVE_truncdfsf2 && from_mode == DFmode && to_mode == SFmode)
        {
          emit_unop_insn (CODE_FOR_truncdfsf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncxfsf2
      if (HAVE_truncxfsf2 && from_mode == XFmode && to_mode == SFmode)
        {
          emit_unop_insn (CODE_FOR_truncxfsf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_trunctfsf2
      if (HAVE_trunctfsf2 && from_mode == TFmode && to_mode == SFmode)
        {
          emit_unop_insn (CODE_FOR_trunctfsf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_truncxfdf2
      if (HAVE_truncxfdf2 && from_mode == XFmode && to_mode == DFmode)
        {
          emit_unop_insn (CODE_FOR_truncxfdf2, to, from, UNKNOWN);
          return;
        }
#endif
#ifdef HAVE_trunctfdf2
      if (HAVE_trunctfdf2 && from_mode == TFmode && to_mode == DFmode)
        {
          emit_unop_insn (CODE_FOR_trunctfdf2, to, from, UNKNOWN);
          return;
        }
#endif

      libcall = (rtx) 0;
      switch (from_mode)
        {
        case SFmode:
          switch (to_mode)
            {
            case DFmode:
              libcall = extendsfdf2_libfunc;
              break;

            case XFmode:
              libcall = extendsfxf2_libfunc;
              break;

            case TFmode:
              libcall = extendsftf2_libfunc;
              break;
              
            default:
              break;
            }
          break;

        case DFmode:
          switch (to_mode)
            {
            case SFmode:
              libcall = truncdfsf2_libfunc;
              break;

            case XFmode:
              libcall = extenddfxf2_libfunc;
              break;

            case TFmode:
              libcall = extenddftf2_libfunc;
              break;
              
            default:
              break;
            }
          break;

        case XFmode:
          switch (to_mode)
            {
            case SFmode:
              libcall = truncxfsf2_libfunc;
              break;

            case DFmode:
              libcall = truncxfdf2_libfunc;
              break;
              
            default:
              break;
            }
          break;

        case TFmode:
          switch (to_mode)
            {
            case SFmode:
              libcall = trunctfsf2_libfunc;
              break;

            case DFmode:
              libcall = trunctfdf2_libfunc;
              break;
              
            default:
              break;
            }
          break;
          
        default:
          break;
        }

      if (libcall == (rtx) 0)
        /* This conversion is not implemented yet.  */
        abort ();

      value = emit_library_call_value (libcall, NULL_RTX, 1, to_mode,
                                       1, from, from_mode);
      emit_move_insn (to, value);
      return;
    }

  /* Now both modes are integers.  */

  /* Handle expanding beyond a word.  */
  if (GET_MODE_BITSIZE (from_mode) < GET_MODE_BITSIZE (to_mode)
      && GET_MODE_BITSIZE (to_mode) > BITS_PER_WORD)
    {
      rtx insns;
      rtx lowpart;
      rtx fill_value;
      rtx lowfrom;
      int i;
      enum machine_mode lowpart_mode;
      int nwords = CEIL (GET_MODE_SIZE (to_mode), UNITS_PER_WORD);

      /* Try converting directly if the insn is supported.  */
      if ((code = can_extend_p (to_mode, from_mode, unsignedp))
          != CODE_FOR_nothing)
        {
          /* If FROM is a SUBREG, put it into a register.  Do this
             so that we always generate the same set of insns for
             better cse'ing; if an intermediate assignment occurred,
             we won't be doing the operation directly on the SUBREG.  */
          if (optimize > 0 && GET_CODE (from) == SUBREG)
            from = force_reg (from_mode, from);
          emit_unop_insn (code, to, from, equiv_code);
          return;
        }
      /* Next, try converting via full word.  */
      else if (GET_MODE_BITSIZE (from_mode) < BITS_PER_WORD
               && ((code = can_extend_p (to_mode, word_mode, unsignedp))
                   != CODE_FOR_nothing))
        {
          if (GET_CODE (to) == REG)
            emit_insn (gen_rtx_CLOBBER (VOIDmode, to));
          convert_move (gen_lowpart (word_mode, to), from, unsignedp);
          emit_unop_insn (code, to,
                          gen_lowpart (word_mode, to), equiv_code);
          return;
        }

      /* No special multiword conversion insn; do it by hand.  */
      start_sequence ();

      /* Since we will turn this into a no conflict block, we must ensure
         that the source does not overlap the target.  */

      if (reg_overlap_mentioned_p (to, from))
        from = force_reg (from_mode, from);

      /* Get a copy of FROM widened to a word, if necessary.  */
      if (GET_MODE_BITSIZE (from_mode) < BITS_PER_WORD)
        lowpart_mode = word_mode;
      else
        lowpart_mode = from_mode;

      lowfrom = convert_to_mode (lowpart_mode, from, unsignedp);

      lowpart = gen_lowpart (lowpart_mode, to);
      emit_move_insn (lowpart, lowfrom);

      /* Compute the value to put in each remaining word.  */
      if (unsignedp)
        fill_value = const0_rtx;
      else
        {
#ifdef HAVE_slt
          if (HAVE_slt
              && insn_data[(int) CODE_FOR_slt].operand[0].mode == word_mode
              && STORE_FLAG_VALUE == -1)
            {
              emit_cmp_insn (lowfrom, const0_rtx, NE, NULL_RTX,
                             lowpart_mode, 0, 0);
              fill_value = gen_reg_rtx (word_mode);
              emit_insn (gen_slt (fill_value));
            }
          else
#endif
            {
              fill_value
                = expand_shift (RSHIFT_EXPR, lowpart_mode, lowfrom,
                                size_int (GET_MODE_BITSIZE (lowpart_mode) - 1),
                                NULL_RTX, 0);
              fill_value = convert_to_mode (word_mode, fill_value, 1);
            }
        }

      /* Fill the remaining words.  */
      for (i = GET_MODE_SIZE (lowpart_mode) / UNITS_PER_WORD; i < nwords; i++)
        {
          int index = (WORDS_BIG_ENDIAN ? nwords - i - 1 : i);
          rtx subword = operand_subword (to, index, 1, to_mode);

          if (subword == 0)
            abort ();

          if (fill_value != subword)
            emit_move_insn (subword, fill_value);
        }

      insns = get_insns ();
      end_sequence ();

      emit_no_conflict_block (insns, to, from, NULL_RTX,
                              gen_rtx_fmt_e (equiv_code, to_mode, copy_rtx (from)));
      return;
    }

  /* Truncating multi-word to a word or less.  */
  if (GET_MODE_BITSIZE (from_mode) > BITS_PER_WORD
      && GET_MODE_BITSIZE (to_mode) <= BITS_PER_WORD)
    {
      if (!((GET_CODE (from) == MEM
             && ! MEM_VOLATILE_P (from)
             && direct_load[(int) to_mode]
             && ! mode_dependent_address_p (XEXP (from, 0)))
            || GET_CODE (from) == REG
            || GET_CODE (from) == SUBREG))
        from = force_reg (from_mode, from);
      convert_move (to, gen_lowpart (word_mode, from), 0);
      return;
    }

  /* Handle pointer conversion */                       /* SPEE 900220 */
  if (to_mode == PQImode)
    {
      if (from_mode != QImode)
        from = convert_to_mode (QImode, from, unsignedp);

#ifdef HAVE_truncqipqi2
      if (HAVE_truncqipqi2)
        {
          emit_unop_insn (CODE_FOR_truncqipqi2, to, from, UNKNOWN);
          return;
        }
#endif /* HAVE_truncqipqi2 */
      abort ();
    }

  if (from_mode == PQImode)
    {
      if (to_mode != QImode)
        {
          from = convert_to_mode (QImode, from, unsignedp);
          from_mode = QImode;
        }
      else
        {
#ifdef HAVE_extendpqiqi2
          if (HAVE_extendpqiqi2)
            {
              emit_unop_insn (CODE_FOR_extendpqiqi2, to, from, UNKNOWN);
              return;
            }
#endif /* HAVE_extendpqiqi2 */
          abort ();
        }
    }

  if (to_mode == PSImode)
    {
      if (from_mode != SImode)
        from = convert_to_mode (SImode, from, unsignedp);

#ifdef HAVE_truncsipsi2
      if (HAVE_truncsipsi2)
        {
          emit_unop_insn (CODE_FOR_truncsipsi2, to, from, UNKNOWN);
          return;
        }
#endif /* HAVE_truncsipsi2 */
      abort ();
    }

  if (from_mode == PSImode)
    {
      if (to_mode != SImode)
        {
          from = convert_to_mode (SImode, from, unsignedp);
          from_mode = SImode;
        }
      else
        {
#ifdef HAVE_extendpsisi2
          if (HAVE_extendpsisi2)
            {
              emit_unop_insn (CODE_FOR_extendpsisi2, to, from, UNKNOWN);
              return;
            }
#endif /* HAVE_extendpsisi2 */
          abort ();
        }
    }

  if (to_mode == PDImode)
    {
      if (from_mode != DImode)
        from = convert_to_mode (DImode, from, unsignedp);

#ifdef HAVE_truncdipdi2
      if (HAVE_truncdipdi2)
        {
          emit_unop_insn (CODE_FOR_truncdipdi2, to, from, UNKNOWN);
          return;
        }
#endif /* HAVE_truncdipdi2 */
      abort ();
    }

  if (from_mode == PDImode)
    {
      if (to_mode != DImode)
        {
          from = convert_to_mode (DImode, from, unsignedp);
          from_mode = DImode;
        }
      else
        {
#ifdef HAVE_extendpdidi2
          if (HAVE_extendpdidi2)
            {
              emit_unop_insn (CODE_FOR_extendpdidi2, to, from, UNKNOWN);
              return;
            }
#endif /* HAVE_extendpdidi2 */
          abort ();
        }
    }

  /* Now follow all the conversions between integers
     no more than a word long.  */

  /* For truncation, usually we can just refer to FROM in a narrower mode.  */
  if (GET_MODE_BITSIZE (to_mode) < GET_MODE_BITSIZE (from_mode)
      && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (to_mode),
                                GET_MODE_BITSIZE (from_mode)))
    {
      if (!((GET_CODE (from) == MEM
             && ! MEM_VOLATILE_P (from)
             && direct_load[(int) to_mode]
             && ! mode_dependent_address_p (XEXP (from, 0)))
            || GET_CODE (from) == REG
            || GET_CODE (from) == SUBREG))
        from = force_reg (from_mode, from);
      if (GET_CODE (from) == REG && REGNO (from) < FIRST_PSEUDO_REGISTER
          && ! HARD_REGNO_MODE_OK (REGNO (from), to_mode))
        from = copy_to_reg (from);
      emit_move_insn (to, gen_lowpart (to_mode, from));
      return;
    }

  /* Handle extension.  */
  if (GET_MODE_BITSIZE (to_mode) > GET_MODE_BITSIZE (from_mode))
    {
      /* Convert directly if that works.  */
      if ((code = can_extend_p (to_mode, from_mode, unsignedp))
          != CODE_FOR_nothing)
        {
          emit_unop_insn (code, to, from, equiv_code);
          return;
        }
      else
        {
          enum machine_mode intermediate;
          rtx tmp;
          tree shift_amount;

          /* Search for a mode to convert via.  */
          for (intermediate = from_mode; intermediate != VOIDmode;
               intermediate = GET_MODE_WIDER_MODE (intermediate))
            if (((can_extend_p (to_mode, intermediate, unsignedp)
                  != CODE_FOR_nothing)
                 || (GET_MODE_SIZE (to_mode) < GET_MODE_SIZE (intermediate)
                     && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (to_mode),
                                               GET_MODE_BITSIZE (intermediate))))
                && (can_extend_p (intermediate, from_mode, unsignedp)
                    != CODE_FOR_nothing))
              {
                convert_move (to, convert_to_mode (intermediate, from,
                                                   unsignedp), unsignedp);
                return;
              }

          /* No suitable intermediate mode.
             Generate what we need with shifts. */
          shift_amount = build_int_2 (GET_MODE_BITSIZE (to_mode)
                                      - GET_MODE_BITSIZE (from_mode), 0);
          from = gen_lowpart (to_mode, force_reg (from_mode, from));
          tmp = expand_shift (LSHIFT_EXPR, to_mode, from, shift_amount,
                              to, unsignedp);
          tmp = expand_shift (RSHIFT_EXPR, to_mode, tmp,  shift_amount,
                              to, unsignedp);
          if (tmp != to)
            emit_move_insn (to, tmp);
          return;
        }
    }

  /* Support special truncate insns for certain modes.  */ 

  if (from_mode == DImode && to_mode == SImode)
    {
#ifdef HAVE_truncdisi2
      if (HAVE_truncdisi2)
        {
          emit_unop_insn (CODE_FOR_truncdisi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == DImode && to_mode == HImode)
    {
#ifdef HAVE_truncdihi2
      if (HAVE_truncdihi2)
        {
          emit_unop_insn (CODE_FOR_truncdihi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == DImode && to_mode == QImode)
    {
#ifdef HAVE_truncdiqi2
      if (HAVE_truncdiqi2)
        {
          emit_unop_insn (CODE_FOR_truncdiqi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == SImode && to_mode == HImode)
    {
#ifdef HAVE_truncsihi2
      if (HAVE_truncsihi2)
        {
          emit_unop_insn (CODE_FOR_truncsihi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == SImode && to_mode == QImode)
    {
#ifdef HAVE_truncsiqi2
      if (HAVE_truncsiqi2)
        {
          emit_unop_insn (CODE_FOR_truncsiqi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == HImode && to_mode == QImode)
    {
#ifdef HAVE_trunchiqi2
      if (HAVE_trunchiqi2)
        {
          emit_unop_insn (CODE_FOR_trunchiqi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == DImode)
    {
#ifdef HAVE_trunctidi2
      if (HAVE_trunctidi2)
        {
          emit_unop_insn (CODE_FOR_trunctidi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == SImode)
    {
#ifdef HAVE_trunctisi2
      if (HAVE_trunctisi2)
        {
          emit_unop_insn (CODE_FOR_trunctisi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == HImode)
    {
#ifdef HAVE_trunctihi2
      if (HAVE_trunctihi2)
        {
          emit_unop_insn (CODE_FOR_trunctihi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  if (from_mode == TImode && to_mode == QImode)
    {
#ifdef HAVE_trunctiqi2
      if (HAVE_trunctiqi2)
        {
          emit_unop_insn (CODE_FOR_trunctiqi2, to, from, UNKNOWN);
          return;
        }
#endif
      convert_move (to, force_reg (from_mode, from), unsignedp);
      return;
    }

  /* Handle truncation of volatile memrefs, and so on;
     the things that couldn't be truncated directly,
     and for which there was no special instruction.  */
  if (GET_MODE_BITSIZE (to_mode) < GET_MODE_BITSIZE (from_mode))
    {
      rtx temp = force_reg (to_mode, gen_lowpart (to_mode, from));
      emit_move_insn (to, temp);
      return;
    }

  /* Mode combination is not recognized.  */
  abort ();
}

/* Return an rtx for a value that would result
   from converting X to mode MODE.
   Both X and MODE may be floating, or both integer.
   UNSIGNEDP is nonzero if X is an unsigned value.
   This can be done by referring to a part of X in place
   or by copying to a new temporary with conversion.

   This function *must not* call protect_from_queue
   except when putting X into an insn (in which case convert_move does it).  */

rtx
convert_to_mode (mode, x, unsignedp)
     enum machine_mode mode;
     rtx x;
     int unsignedp;
{
  return convert_modes (mode, VOIDmode, x, unsignedp);
}

/* Return an rtx for a value that would result
   from converting X from mode OLDMODE to mode MODE.
   Both modes may be floating, or both integer.
   UNSIGNEDP is nonzero if X is an unsigned value.

   This can be done by referring to a part of X in place
   or by copying to a new temporary with conversion.

   You can give VOIDmode for OLDMODE, if you are sure X has a nonvoid mode.

   This function *must not* call protect_from_queue
   except when putting X into an insn (in which case convert_move does it).  */

rtx
convert_modes (mode, oldmode, x, unsignedp)
     enum machine_mode mode, oldmode;
     rtx x;
     int unsignedp;
{
  register rtx temp;

  /* If FROM is a SUBREG that indicates that we have already done at least
     the required extension, strip it.  */

  if (GET_CODE (x) == SUBREG && SUBREG_PROMOTED_VAR_P (x)
      && GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))) >= GET_MODE_SIZE (mode)
      && SUBREG_PROMOTED_UNSIGNED_P (x) == unsignedp)
    x = gen_lowpart (mode, x);

  if (GET_MODE (x) != VOIDmode)
    oldmode = GET_MODE (x);
 
  if (mode == oldmode)
    return x;

  /* There is one case that we must handle specially: If we are converting
     a CONST_INT into a mode whose size is twice HOST_BITS_PER_WIDE_INT and
     we are to interpret the constant as unsigned, gen_lowpart will do
     the wrong if the constant appears negative.  What we want to do is
     make the high-order word of the constant zero, not all ones.  */

  if (unsignedp && GET_MODE_CLASS (mode) == MODE_INT
      && GET_MODE_BITSIZE (mode) == 2 * HOST_BITS_PER_WIDE_INT
      && GET_CODE (x) == CONST_INT && INTVAL (x) < 0)
    {
      HOST_WIDE_INT val = INTVAL (x);

      if (oldmode != VOIDmode
          && HOST_BITS_PER_WIDE_INT > GET_MODE_BITSIZE (oldmode))
        {
          int width = GET_MODE_BITSIZE (oldmode);

          /* We need to zero extend VAL.  */
          val &= ((HOST_WIDE_INT) 1 << width) - 1;
        }

      return immed_double_const (val, (HOST_WIDE_INT) 0, mode);
    }

  /* We can do this with a gen_lowpart if both desired and current modes
     are integer, and this is either a constant integer, a register, or a
     non-volatile MEM.  Except for the constant case where MODE is no
     wider than HOST_BITS_PER_WIDE_INT, we must be narrowing the operand.  */

  if ((GET_CODE (x) == CONST_INT
       && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
      || (GET_MODE_CLASS (mode) == MODE_INT
          && GET_MODE_CLASS (oldmode) == MODE_INT
          && (GET_CODE (x) == CONST_DOUBLE
              || (GET_MODE_SIZE (mode) <= GET_MODE_SIZE (oldmode)
                  && ((GET_CODE (x) == MEM && ! MEM_VOLATILE_P (x)
                       && direct_load[(int) mode])
                      || (GET_CODE (x) == REG
                          && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
                                                    GET_MODE_BITSIZE (GET_MODE (x)))))))))
    {
      /* ?? If we don't know OLDMODE, we have to assume here that
         X does not need sign- or zero-extension.   This may not be
         the case, but it's the best we can do.  */
      if (GET_CODE (x) == CONST_INT && oldmode != VOIDmode
          && GET_MODE_SIZE (mode) > GET_MODE_SIZE (oldmode))
        {
          HOST_WIDE_INT val = INTVAL (x);
          int width = GET_MODE_BITSIZE (oldmode);

          /* We must sign or zero-extend in this case.  Start by
             zero-extending, then sign extend if we need to.  */
          val &= ((HOST_WIDE_INT) 1 << width) - 1;
          if (! unsignedp
              && (val & ((HOST_WIDE_INT) 1 << (width - 1))))
            val |= (HOST_WIDE_INT) (-1) << width;

          return GEN_INT (val);
        }

      return gen_lowpart (mode, x);
    }

  temp = gen_reg_rtx (mode);
  convert_move (temp, x, unsignedp);
  return temp;
}
\f

/* This macro is used to determine what the largest unit size that
   move_by_pieces can use is. */

/* MOVE_MAX_PIECES is the number of bytes at a time which we can
   move efficiently, as opposed to  MOVE_MAX which is the maximum
   number of bytes we can move with a single instruction. */

#ifndef MOVE_MAX_PIECES
#define MOVE_MAX_PIECES   MOVE_MAX
#endif

/* Generate several move instructions to copy LEN bytes
   from block FROM to block TO.  (These are MEM rtx's with BLKmode).
   The caller must pass FROM and TO
    through protect_from_queue before calling.
   ALIGN is maximum alignment we can assume.  */

void
move_by_pieces (to, from, len, align)
     rtx to, from;
     unsigned HOST_WIDE_INT len;
     unsigned int align;
{
  struct move_by_pieces data;
  rtx to_addr = XEXP (to, 0), from_addr = XEXP (from, 0);
  unsigned int max_size = MOVE_MAX_PIECES + 1;
  enum machine_mode mode = VOIDmode, tmode;
  enum insn_code icode;

  data.offset = 0;
  data.to_addr = to_addr;
  data.from_addr = from_addr;
  data.to = to;
  data.from = from;
  data.autinc_to
    = (GET_CODE (to_addr) == PRE_INC || GET_CODE (to_addr) == PRE_DEC
       || GET_CODE (to_addr) == POST_INC || GET_CODE (to_addr) == POST_DEC);
  data.autinc_from
    = (GET_CODE (from_addr) == PRE_INC || GET_CODE (from_addr) == PRE_DEC
       || GET_CODE (from_addr) == POST_INC
       || GET_CODE (from_addr) == POST_DEC);

  data.explicit_inc_from = 0;
  data.explicit_inc_to = 0;
  data.reverse
    = (GET_CODE (to_addr) == PRE_DEC || GET_CODE (to_addr) == POST_DEC);
  if (data.reverse) data.offset = len;
  data.len = len;

  /* If copying requires more than two move insns,
     copy addresses to registers (to make displacements shorter)
     and use post-increment if available.  */
  if (!(data.autinc_from && data.autinc_to)
      && move_by_pieces_ninsns (len, align) > 2)
    {
      /* Find the mode of the largest move... */
      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           tmode != VOIDmode; tmode = GET_MODE_WIDER_MODE (tmode))
        if (GET_MODE_SIZE (tmode) < max_size)
          mode = tmode;

      if (USE_LOAD_PRE_DECREMENT (mode) && data.reverse && ! data.autinc_from)
        {
          data.from_addr = copy_addr_to_reg (plus_constant (from_addr, len));
          data.autinc_from = 1;
          data.explicit_inc_from = -1;
        }
      if (USE_LOAD_POST_INCREMENT (mode) && ! data.autinc_from)
        {
          data.from_addr = copy_addr_to_reg (from_addr);
          data.autinc_from = 1;
          data.explicit_inc_from = 1;
        }
      if (!data.autinc_from && CONSTANT_P (from_addr))
        data.from_addr = copy_addr_to_reg (from_addr);
      if (USE_STORE_PRE_DECREMENT (mode) && data.reverse && ! data.autinc_to)
        {
          data.to_addr = copy_addr_to_reg (plus_constant (to_addr, len));
          data.autinc_to = 1;
          data.explicit_inc_to = -1;
        }
      if (USE_STORE_POST_INCREMENT (mode) && ! data.reverse && ! data.autinc_to)
        {
          data.to_addr = copy_addr_to_reg (to_addr);
          data.autinc_to = 1;
          data.explicit_inc_to = 1;
        }
      if (!data.autinc_to && CONSTANT_P (to_addr))
        data.to_addr = copy_addr_to_reg (to_addr);
    }

  if (! SLOW_UNALIGNED_ACCESS (word_mode, align)
      || align > MOVE_MAX * BITS_PER_UNIT || align >= BIGGEST_ALIGNMENT)
    align = MOVE_MAX * BITS_PER_UNIT;

  /* First move what we can in the largest integer mode, then go to
     successively smaller modes.  */

  while (max_size > 1)
    {
      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           tmode != VOIDmode; tmode = GET_MODE_WIDER_MODE (tmode))
        if (GET_MODE_SIZE (tmode) < max_size)
          mode = tmode;

      if (mode == VOIDmode)
        break;

      icode = mov_optab->handlers[(int) mode].insn_code;
      if (icode != CODE_FOR_nothing && align >= GET_MODE_ALIGNMENT (mode))
        move_by_pieces_1 (GEN_FCN (icode), mode, &data);

      max_size = GET_MODE_SIZE (mode);
    }

  /* The code above should have handled everything.  */
  if (data.len > 0)
    abort ();
}

/* Return number of insns required to move L bytes by pieces.
   ALIGN (in bytes) is maximum alignment we can assume.  */

static unsigned HOST_WIDE_INT
move_by_pieces_ninsns (l, align)
     unsigned HOST_WIDE_INT l;
     unsigned int align;
{
  unsigned HOST_WIDE_INT n_insns = 0;
  unsigned HOST_WIDE_INT max_size = MOVE_MAX + 1;

  if (! SLOW_UNALIGNED_ACCESS (word_mode, align)
      || align > MOVE_MAX * BITS_PER_UNIT || align >= BIGGEST_ALIGNMENT)
    align = MOVE_MAX * BITS_PER_UNIT;

  while (max_size > 1)
    {
      enum machine_mode mode = VOIDmode, tmode;
      enum insn_code icode;

      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           tmode != VOIDmode; tmode = GET_MODE_WIDER_MODE (tmode))
        if (GET_MODE_SIZE (tmode) < max_size)
          mode = tmode;

      if (mode == VOIDmode)
        break;

      icode = mov_optab->handlers[(int) mode].insn_code;
      if (icode != CODE_FOR_nothing && align >= GET_MODE_ALIGNMENT (mode))
        n_insns += l / GET_MODE_SIZE (mode), l %= GET_MODE_SIZE (mode);

      max_size = GET_MODE_SIZE (mode);
    }

  return n_insns;
}

/* Subroutine of move_by_pieces.  Move as many bytes as appropriate
   with move instructions for mode MODE.  GENFUN is the gen_... function
   to make a move insn for that mode.  DATA has all the other info.  */

static void
move_by_pieces_1 (genfun, mode, data)
     rtx (*genfun) PARAMS ((rtx, ...));
     enum machine_mode mode;
     struct move_by_pieces *data;
{
  unsigned int size = GET_MODE_SIZE (mode);
  rtx to1, from1;

  while (data->len >= size)
    {
      if (data->reverse)
        data->offset -= size;

      if (data->autinc_to)
        {
          to1 = gen_rtx_MEM (mode, data->to_addr);
          MEM_COPY_ATTRIBUTES (to1, data->to);
        }
      else
        to1 = change_address (data->to, mode,
                              plus_constant (data->to_addr, data->offset));

      if (data->autinc_from)
        {
          from1 = gen_rtx_MEM (mode, data->from_addr);
          MEM_COPY_ATTRIBUTES (from1, data->from);
        }
      else
        from1 = change_address (data->from, mode,
                                plus_constant (data->from_addr, data->offset));

      if (HAVE_PRE_DECREMENT && data->explicit_inc_to < 0)
        emit_insn (gen_add2_insn (data->to_addr, GEN_INT (-size)));
      if (HAVE_PRE_DECREMENT && data->explicit_inc_from < 0)
        emit_insn (gen_add2_insn (data->from_addr, GEN_INT (-size)));

      emit_insn ((*genfun) (to1, from1));

      if (HAVE_POST_INCREMENT && data->explicit_inc_to > 0)
        emit_insn (gen_add2_insn (data->to_addr, GEN_INT (size)));
      if (HAVE_POST_INCREMENT && data->explicit_inc_from > 0)
        emit_insn (gen_add2_insn (data->from_addr, GEN_INT (size)));

      if (! data->reverse)
        data->offset += size;

      data->len -= size;
    }
}
\f
/* Emit code to move a block Y to a block X.
   This may be done with string-move instructions,
   with multiple scalar move instructions, or with a library call.

   Both X and Y must be MEM rtx's (perhaps inside VOLATILE)
   with mode BLKmode.
   SIZE is an rtx that says how long they are.
   ALIGN is the maximum alignment we can assume they have.

   Return the address of the new block, if memcpy is called and returns it,
   0 otherwise.  */

rtx
emit_block_move (x, y, size, align)
     rtx x, y;
     rtx size;
     unsigned int align;
{
  rtx retval = 0;
#ifdef TARGET_MEM_FUNCTIONS
  static tree fn;
  tree call_expr, arg_list;
#endif

  if (GET_MODE (x) != BLKmode)
    abort ();

  if (GET_MODE (y) != BLKmode)
    abort ();

  x = protect_from_queue (x, 1);
  y = protect_from_queue (y, 0);
  size = protect_from_queue (size, 0);

  if (GET_CODE (x) != MEM)
    abort ();
  if (GET_CODE (y) != MEM)
    abort ();
  if (size == 0)
    abort ();

  if (GET_CODE (size) == CONST_INT && MOVE_BY_PIECES_P (INTVAL (size), align))
    move_by_pieces (x, y, INTVAL (size), align);
  else
    {
      /* Try the most limited insn first, because there's no point
         including more than one in the machine description unless
         the more limited one has some advantage.  */

      rtx opalign = GEN_INT (align / BITS_PER_UNIT);
      enum machine_mode mode;

      /* Since this is a move insn, we don't care about volatility.  */
      volatile_ok = 1;

      for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
           mode = GET_MODE_WIDER_MODE (mode))
        {
          enum insn_code code = movstr_optab[(int) mode];
          insn_operand_predicate_fn pred;

          if (code != CODE_FOR_nothing
              /* We don't need MODE to be narrower than BITS_PER_HOST_WIDE_INT
                 here because if SIZE is less than the mode mask, as it is
                 returned by the macro, it will definitely be less than the
                 actual mode mask.  */
              && ((GET_CODE (size) == CONST_INT
                   && ((unsigned HOST_WIDE_INT) INTVAL (size)
                       <= (GET_MODE_MASK (mode) >> 1)))
                  || GET_MODE_BITSIZE (mode) >= BITS_PER_WORD)
              && ((pred = insn_data[(int) code].operand[0].predicate) == 0
                  || (*pred) (x, BLKmode))
              && ((pred = insn_data[(int) code].operand[1].predicate) == 0
                  || (*pred) (y, BLKmode))
              && ((pred = insn_data[(int) code].operand[3].predicate) == 0
                  || (*pred) (opalign, VOIDmode)))
            {
              rtx op2;
              rtx last = get_last_insn ();
              rtx pat;

              op2 = convert_to_mode (mode, size, 1);
              pred = insn_data[(int) code].operand[2].predicate;
              if (pred != 0 && ! (*pred) (op2, mode))
                op2 = copy_to_mode_reg (mode, op2);

              pat = GEN_FCN ((int) code) (x, y, op2, opalign);
              if (pat)
                {
                  emit_insn (pat);
                  volatile_ok = 0;
                  return 0;
                }
              else
                delete_insns_since (last);
            }
        }

      volatile_ok = 0;

      /* X, Y, or SIZE may have been passed through protect_from_queue.

         It is unsafe to save the value generated by protect_from_queue
         and reuse it later.  Consider what happens if emit_queue is
         called before the return value from protect_from_queue is used.

         Expansion of the CALL_EXPR below will call emit_queue before
         we are finished emitting RTL for argument setup.  So if we are
         not careful we could get the wrong value for an argument.

         To avoid this problem we go ahead and emit code to copy X, Y &
         SIZE into new pseudos.  We can then place those new pseudos
         into an RTL_EXPR and use them later, even after a call to
         emit_queue. 

         Note this is not strictly needed for library calls since they
         do not call emit_queue before loading their arguments.  However,
         we may need to have library calls call emit_queue in the future
         since failing to do so could cause problems for targets which
         define SMALL_REGISTER_CLASSES and pass arguments in registers.  */
      x = copy_to_mode_reg (Pmode, XEXP (x, 0));
      y = copy_to_mode_reg (Pmode, XEXP (y, 0));

#ifdef TARGET_MEM_FUNCTIONS
      size = copy_to_mode_reg (TYPE_MODE (sizetype), size);
#else
      size = convert_to_mode (TYPE_MODE (integer_type_node), size,
                              TREE_UNSIGNED (integer_type_node));
      size = copy_to_mode_reg (TYPE_MODE (integer_type_node), size);
#endif

#ifdef TARGET_MEM_FUNCTIONS
      /* It is incorrect to use the libcall calling conventions to call
         memcpy in this context.

         This could be a user call to memcpy and the user may wish to
         examine the return value from memcpy.

         For targets where libcalls and normal calls have different conventions
         for returning pointers, we could end up generating incorrect code. 

         So instead of using a libcall sequence we build up a suitable
         CALL_EXPR and expand the call in the normal fashion.  */
      if (fn == NULL_TREE)
        {
          tree fntype;

          /* This was copied from except.c, I don't know if all this is
             necessary in this context or not.  */
          fn = get_identifier ("memcpy");
          push_obstacks_nochange ();
          end_temporary_allocation ();
          fntype = build_pointer_type (void_type_node);
          fntype = build_function_type (fntype, NULL_TREE);
          fn = build_decl (FUNCTION_DECL, fn, fntype);
          ggc_add_tree_root (&fn, 1);
          DECL_EXTERNAL (fn) = 1;
          TREE_PUBLIC (fn) = 1;
          DECL_ARTIFICIAL (fn) = 1;
          make_decl_rtl (fn, NULL_PTR, 1);
          assemble_external (fn);
          pop_obstacks ();
        }

      /* We need to make an argument list for the function call. 

         memcpy has three arguments, the first two are void * addresses and
         the last is a size_t byte count for the copy.  */
      arg_list
        = build_tree_list (NULL_TREE,
                           make_tree (build_pointer_type (void_type_node), x));
      TREE_CHAIN (arg_list)
        = build_tree_list (NULL_TREE,
                           make_tree (build_pointer_type (void_type_node), y));
      TREE_CHAIN (TREE_CHAIN (arg_list))
         = build_tree_list (NULL_TREE, make_tree (sizetype, size));
      TREE_CHAIN (TREE_CHAIN (TREE_CHAIN (arg_list))) = NULL_TREE;

      /* Now we have to build up the CALL_EXPR itself.  */
      call_expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
      call_expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
                         call_expr, arg_list, NULL_TREE);
      TREE_SIDE_EFFECTS (call_expr) = 1;

      retval = expand_expr (call_expr, NULL_RTX, VOIDmode, 0);
#else
      emit_library_call (bcopy_libfunc, 0,
                         VOIDmode, 3, y, Pmode, x, Pmode,
                         convert_to_mode (TYPE_MODE (integer_type_node), size,
                                          TREE_UNSIGNED (integer_type_node)),
                         TYPE_MODE (integer_type_node));
#endif
    }

  return retval;
}
\f
/* Copy all or part of a value X into registers starting at REGNO.
   The number of registers to be filled is NREGS.  */

void
move_block_to_reg (regno, x, nregs, mode)
     int regno;
     rtx x;
     int nregs;
     enum machine_mode mode;
{
  int i;
#ifdef HAVE_load_multiple
  rtx pat; 
  rtx last;
#endif

  if (nregs == 0)
    return;

  if (CONSTANT_P (x) && ! LEGITIMATE_CONSTANT_P (x))
    x = validize_mem (force_const_mem (mode, x));

  /* See if the machine can do this with a load multiple insn.  */
#ifdef HAVE_load_multiple
  if (HAVE_load_multiple)
    {
      last = get_last_insn ();
      pat = gen_load_multiple (gen_rtx_REG (word_mode, regno), x,
                               GEN_INT (nregs));
      if (pat)
        {
          emit_insn (pat);
          return;
        }
      else
        delete_insns_since (last);
    }
#endif

  for (i = 0; i < nregs; i++)
    emit_move_insn (gen_rtx_REG (word_mode, regno + i),
                    operand_subword_force (x, i, mode));
}

/* Copy all or part of a BLKmode value X out of registers starting at REGNO.
   The number of registers to be filled is NREGS.  SIZE indicates the number
   of bytes in the object X.  */


void
move_block_from_reg (regno, x, nregs, size)
     int regno;
     rtx x;
     int nregs;
     int size;
{
  int i;
#ifdef HAVE_store_multiple
  rtx pat; 
  rtx last;
#endif
  enum machine_mode mode;

  /* If SIZE is that of a mode no bigger than a word, just use that
     mode's store operation.  */
  if (size <= UNITS_PER_WORD
      && (mode = mode_for_size (size * BITS_PER_UNIT, MODE_INT, 0)) != BLKmode)
    {
      emit_move_insn (change_address (x, mode, NULL),
                      gen_rtx_REG (mode, regno));
      return;
    }
    
  /* Blocks smaller than a word on a BYTES_BIG_ENDIAN machine must be aligned
     to the left before storing to memory.  Note that the previous test
     doesn't handle all cases (e.g. SIZE == 3).  */
  if (size < UNITS_PER_WORD && BYTES_BIG_ENDIAN)
    {
      rtx tem = operand_subword (x, 0, 1, BLKmode);
      rtx shift;

      if (tem == 0)
        abort ();

      shift = expand_shift (LSHIFT_EXPR, word_mode,
                            gen_rtx_REG (word_mode, regno),
                            build_int_2 ((UNITS_PER_WORD - size)
                                         * BITS_PER_UNIT, 0), NULL_RTX, 0);
      emit_move_insn (tem, shift);
      return;
    }

  /* See if the machine can do this with a store multiple insn.  */
#ifdef HAVE_store_multiple
  if (HAVE_store_multiple)
    {
      last = get_last_insn ();
      pat = gen_store_multiple (x, gen_rtx_REG (word_mode, regno),
                                GEN_INT (nregs));
      if (pat)
        {
          emit_insn (pat);
          return;
        }
      else
        delete_insns_since (last);
    }
#endif

  for (i = 0; i < nregs; i++)
    {
      rtx tem = operand_subword (x, i, 1, BLKmode);

      if (tem == 0)
        abort ();

      emit_move_insn (tem, gen_rtx_REG (word_mode, regno + i));
    }
}

/* Emit code to move a block SRC to a block DST, where DST is non-consecutive
   registers represented by a PARALLEL.  SSIZE represents the total size of
   block SRC in bytes, or -1 if not known.  ALIGN is the known alignment of
   SRC in bits.  */
/* ??? If SSIZE % UNITS_PER_WORD != 0, we make the blatent assumption that
   the balance will be in what would be the low-order memory addresses, i.e.
   left justified for big endian, right justified for little endian.  This
   happens to be true for the targets currently using this support.  If this
   ever changes, a new target macro along the lines of FUNCTION_ARG_PADDING
   would be needed.  */

void
emit_group_load (dst, orig_src, ssize, align)
     rtx dst, orig_src;
     unsigned int align;
     int ssize;
{
  rtx *tmps, src;
  int start, i;

  if (GET_CODE (dst) != PARALLEL)
    abort ();

  /* Check for a NULL entry, used to indicate that the parameter goes
     both on the stack and in registers.  */
  if (XEXP (XVECEXP (dst, 0, 0), 0))
    start = 0;
  else
    start = 1;

  tmps = (rtx *) alloca (sizeof(rtx) * XVECLEN (dst, 0));

  /* If we won't be loading directly from memory, protect the real source
     from strange tricks we might play.  */
  src = orig_src;
  if (GET_CODE (src) != MEM)
    {
      if (GET_MODE (src) == VOIDmode)
        src = gen_reg_rtx (GET_MODE (dst));
      else
        src = gen_reg_rtx (GET_MODE (orig_src));
      emit_move_insn (src, orig_src);
    }

  /* Process the pieces.  */
  for (i = start; i < XVECLEN (dst, 0); i++)
    {
      enum machine_mode mode = GET_MODE (XEXP (XVECEXP (dst, 0, i), 0));
      HOST_WIDE_INT bytepos = INTVAL (XEXP (XVECEXP (dst, 0, i), 1));
      unsigned int bytelen = GET_MODE_SIZE (mode);
      int shift = 0;

      /* Handle trailing fragments that run over the size of the struct.  */
      if (ssize >= 0 && bytepos + bytelen > ssize)
        {
          shift = (bytelen - (ssize - bytepos)) * BITS_PER_UNIT;
          bytelen = ssize - bytepos;
          if (bytelen <= 0)
            abort ();
        }

      /* Optimize the access just a bit.  */
      if (GET_CODE (src) == MEM
          && align >= GET_MODE_ALIGNMENT (mode)
          && bytepos * BITS_PER_UNIT % GET_MODE_ALIGNMENT (mode) == 0
          && bytelen == GET_MODE_SIZE (mode))
        {
          tmps[i] = gen_reg_rtx (mode);
          emit_move_insn (tmps[i],
                          change_address (src, mode,
                                          plus_constant (XEXP (src, 0),
                                                         bytepos)));
        }
      else if (GET_CODE (src) == CONCAT)
        {
          if (bytepos == 0
              && bytelen == GET_MODE_SIZE (GET_MODE (XEXP (src, 0))))
            tmps[i] = XEXP (src, 0);
          else if (bytepos == GET_MODE_SIZE (GET_MODE (XEXP (src, 0)))
                   && bytelen == GET_MODE_SIZE (GET_MODE (XEXP (src, 1))))
            tmps[i] = XEXP (src, 1);
          else
            abort ();
        }
      else
        tmps[i] = extract_bit_field (src, bytelen * BITS_PER_UNIT,
                                     bytepos * BITS_PER_UNIT, 1, NULL_RTX,
                                     mode, mode, align, ssize);

      if (BYTES_BIG_ENDIAN && shift)
        expand_binop (mode, ashl_optab, tmps[i], GEN_INT (shift),
                      tmps[i], 0, OPTAB_WIDEN);
    }

  emit_queue();

  /* Copy the extracted pieces into the proper (probable) hard regs.  */
  for (i = start; i < XVECLEN (dst, 0); i++)
    emit_move_insn (XEXP (XVECEXP (dst, 0, i), 0), tmps[i]);
}

/* Emit code to move a block SRC to a block DST, where SRC is non-consecutive
   registers represented by a PARALLEL.  SSIZE represents the total size of
   block DST, or -1 if not known.  ALIGN is the known alignment of DST.  */

void
emit_group_store (orig_dst, src, ssize, align)
     rtx orig_dst, src;
     int ssize;
     unsigned int align;
{
  rtx *tmps, dst;
  int start, i;

  if (GET_CODE (src) != PARALLEL)
    abort ();

  /* Check for a NULL entry, used to indicate that the parameter goes
     both on the stack and in registers.  */
  if (XEXP (XVECEXP (src, 0, 0), 0))
    start = 0;
  else
    start = 1;

  tmps = (rtx *) alloca (sizeof(rtx) * XVECLEN (src, 0));

  /* Copy the (probable) hard regs into pseudos.  */
  for (i = start; i < XVECLEN (src, 0); i++)
    {
      rtx reg = XEXP (XVECEXP (src, 0, i), 0);
      tmps[i] = gen_reg_rtx (GET_MODE (reg));
      emit_move_insn (tmps[i], reg);
    }
  emit_queue();

  /* If we won't be storing directly into memory, protect the real destination
     from strange tricks we might play.  */
  dst = orig_dst;
  if (GET_CODE (dst) == PARALLEL)
    {
      rtx temp;

      /* We can get a PARALLEL dst if there is a conditional expression in
         a return statement.  In that case, the dst and src are the same,
         so no action is necessary.  */
      if (rtx_equal_p (dst, src))
        return;

      /* It is unclear if we can ever reach here, but we may as well handle
         it.  Allocate a temporary, and split this into a store/load to/from
         the temporary.  */

      temp = assign_stack_temp (GET_MODE (dst), ssize, 0);
      emit_group_store (temp, src, ssize, align);
      emit_group_load (dst, temp, ssize, align);
      return;
    }
  else if (GET_CODE (dst) != MEM)
    {
      dst = gen_reg_rtx (GET_MODE (orig_dst));
      /* Make life a bit easier for combine.  */
      emit_move_insn (dst, const0_rtx);
    }
  else if (! MEM_IN_STRUCT_P (dst))
    {
      /* store_bit_field requires that memory operations have
         mem_in_struct_p set; we might not.  */

      dst = copy_rtx (orig_dst);
      MEM_SET_IN_STRUCT_P (dst, 1);
    }

  /* Process the pieces.  */
  for (i = start; i < XVECLEN (src, 0); i++)
    {
      HOST_WIDE_INT bytepos = INTVAL (XEXP (XVECEXP (src, 0, i), 1));
      enum machine_mode mode = GET_MODE (tmps[i]);
      unsigned int bytelen = GET_MODE_SIZE (mode);

      /* Handle trailing fragments that run over the size of the struct.  */
      if (ssize >= 0 && bytepos + bytelen > ssize)
        {
          if (BYTES_BIG_ENDIAN)
            {
              int shift = (bytelen - (ssize - bytepos)) * BITS_PER_UNIT;
              expand_binop (mode, ashr_optab, tmps[i], GEN_INT (shift),
                            tmps[i], 0, OPTAB_WIDEN);
            }
          bytelen = ssize - bytepos;
        }

      /* Optimize the access just a bit.  */
      if (GET_CODE (dst) == MEM
          && align >= GET_MODE_ALIGNMENT (mode)
          && bytepos * BITS_PER_UNIT % GET_MODE_ALIGNMENT (mode) == 0
          && bytelen == GET_MODE_SIZE (mode))
        emit_move_insn (change_address (dst, mode,
                                        plus_constant (XEXP (dst, 0),
                                                       bytepos)),
                        tmps[i]);
      else
        store_bit_field (dst, bytelen * BITS_PER_UNIT, bytepos * BITS_PER_UNIT,
                           mode, tmps[i], align, ssize);
    }

  emit_queue();

  /* Copy from the pseudo into the (probable) hard reg.  */
  if (GET_CODE (dst) == REG)
    emit_move_insn (orig_dst, dst);
}

/* Generate code to copy a BLKmode object of TYPE out of a
   set of registers starting with SRCREG into TGTBLK.  If TGTBLK
   is null, a stack temporary is created.  TGTBLK is returned.

   The primary purpose of this routine is to handle functions
   that return BLKmode structures in registers.  Some machines
   (the PA for example) want to return all small structures
   in registers regardless of the structure's alignment. */

rtx
copy_blkmode_from_reg (tgtblk, srcreg, type)
     rtx tgtblk;
     rtx srcreg;
     tree type;
{
  unsigned HOST_WIDE_INT bytes = int_size_in_bytes (type);
  rtx src = NULL, dst = NULL;
  unsigned HOST_WIDE_INT bitsize = MIN (TYPE_ALIGN (type), BITS_PER_WORD);
  unsigned HOST_WIDE_INT bitpos, xbitpos, big_endian_correction = 0;

  if (tgtblk == 0)
    {
      tgtblk = assign_stack_temp (BLKmode, bytes, 0);
      MEM_SET_IN_STRUCT_P (tgtblk, AGGREGATE_TYPE_P (type));
      preserve_temp_slots (tgtblk);
    }
      
  /* This code assumes srcreg is at least a full word.  If it isn't,
     copy it into a new pseudo which is a full word.  */
  if (GET_MODE (srcreg) != BLKmode
      && GET_MODE_SIZE (GET_MODE (srcreg)) < UNITS_PER_WORD)
    srcreg = convert_to_mode (word_mode, srcreg, TREE_UNSIGNED (type));

  /* Structures whose size is not a multiple of a word are aligned
     to the least significant byte (to the right).  On a BYTES_BIG_ENDIAN
     machine, this means we must skip the empty high order bytes when
     calculating the bit offset.  */
  if (BYTES_BIG_ENDIAN && bytes % UNITS_PER_WORD)
    big_endian_correction
      = (BITS_PER_WORD - ((bytes % UNITS_PER_WORD) * BITS_PER_UNIT));

  /* Copy the structure BITSIZE bites at a time.
     
     We could probably emit more efficient code for machines which do not use
     strict alignment, but it doesn't seem worth the effort at the current
     time.  */
  for (bitpos = 0, xbitpos = big_endian_correction;
       bitpos < bytes * BITS_PER_UNIT;
       bitpos += bitsize, xbitpos += bitsize)
    {
      /* We need a new source operand each time xbitpos is on a 
         word boundary and when xbitpos == big_endian_correction
         (the first time through).  */
      if (xbitpos % BITS_PER_WORD == 0
          || xbitpos == big_endian_correction)
        src = operand_subword_force (srcreg, xbitpos / BITS_PER_WORD, BLKmode);

      /* We need a new destination operand each time bitpos is on
         a word boundary.  */
      if (bitpos % BITS_PER_WORD == 0)
        dst = operand_subword (tgtblk, bitpos / BITS_PER_WORD, 1, BLKmode);
              
      /* Use xbitpos for the source extraction (right justified) and
         xbitpos for the destination store (left justified).  */
      store_bit_field (dst, bitsize, bitpos % BITS_PER_WORD, word_mode,
                       extract_bit_field (src, bitsize,
                                          xbitpos % BITS_PER_WORD, 1,
                                          NULL_RTX, word_mode, word_mode,
                                          bitsize, BITS_PER_WORD),
                       bitsize, BITS_PER_WORD);
    }

  return tgtblk;
}

/* Add a USE expression for REG to the (possibly empty) list pointed
   to by CALL_FUSAGE.  REG must denote a hard register.  */

void
use_reg (call_fusage, reg)
     rtx *call_fusage, reg;
{
  if (GET_CODE (reg) != REG
      || REGNO (reg) >= FIRST_PSEUDO_REGISTER)
    abort();

  *call_fusage
    = gen_rtx_EXPR_LIST (VOIDmode,
                         gen_rtx_USE (VOIDmode, reg), *call_fusage);
}

/* Add USE expressions to *CALL_FUSAGE for each of NREGS consecutive regs,
   starting at REGNO.  All of these registers must be hard registers.  */

void
use_regs (call_fusage, regno, nregs)
     rtx *call_fusage;
     int regno;
     int nregs;
{
  int i;

  if (regno + nregs > FIRST_PSEUDO_REGISTER)
    abort ();

  for (i = 0; i < nregs; i++)
    use_reg (call_fusage, gen_rtx_REG (reg_raw_mode[regno + i], regno + i));
}

/* Add USE expressions to *CALL_FUSAGE for each REG contained in the
   PARALLEL REGS.  This is for calls that pass values in multiple
   non-contiguous locations.  The Irix 6 ABI has examples of this.  */

void
use_group_regs (call_fusage, regs)
     rtx *call_fusage;
     rtx regs;
{
  int i;

  for (i = 0; i < XVECLEN (regs, 0); i++)
    {
      rtx reg = XEXP (XVECEXP (regs, 0, i), 0);

      /* A NULL entry means the parameter goes both on the stack and in
         registers.  This can also be a MEM for targets that pass values
         partially on the stack and partially in registers.  */
      if (reg != 0 && GET_CODE (reg) == REG)
        use_reg (call_fusage, reg);
    }
}
\f
/* Generate several move instructions to clear LEN bytes of block TO.  (A MEM
   rtx with BLKmode).  The caller must pass TO through protect_from_queue
   before calling. ALIGN is maximum alignment we can assume.  */

static void
clear_by_pieces (to, len, align)
     rtx to;
     unsigned HOST_WIDE_INT len;
     unsigned int align;
{
  struct clear_by_pieces data;
  rtx to_addr = XEXP (to, 0);
  unsigned HOST_WIDE_INT max_size = MOVE_MAX_PIECES + 1;
  enum machine_mode mode = VOIDmode, tmode;
  enum insn_code icode;

  data.offset = 0;
  data.to_addr = to_addr;
  data.to = to;
  data.autinc_to
    = (GET_CODE (to_addr) == PRE_INC || GET_CODE (to_addr) == PRE_DEC
       || GET_CODE (to_addr) == POST_INC || GET_CODE (to_addr) == POST_DEC);

  data.explicit_inc_to = 0;
  data.reverse
    = (GET_CODE (to_addr) == PRE_DEC || GET_CODE (to_addr) == POST_DEC);
  if (data.reverse) data.offset = len;
  data.len = len;

  /* If copying requires more than two move insns,
     copy addresses to registers (to make displacements shorter)
     and use post-increment if available.  */
  if (!data.autinc_to
      && move_by_pieces_ninsns (len, align) > 2)
    {
      /* Determine the main mode we'll be using */
      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           tmode != VOIDmode; tmode = GET_MODE_WIDER_MODE (tmode))
        if (GET_MODE_SIZE (tmode) < max_size)
          mode = tmode;

      if (USE_STORE_PRE_DECREMENT (mode) && data.reverse && ! data.autinc_to)
        {
          data.to_addr = copy_addr_to_reg (plus_constant (to_addr, len));
          data.autinc_to = 1;
          data.explicit_inc_to = -1;
        }

      if (USE_STORE_POST_INCREMENT (mode) && ! data.reverse
          && ! data.autinc_to)
        {
          data.to_addr = copy_addr_to_reg (to_addr);
          data.autinc_to = 1;
          data.explicit_inc_to = 1;
        }

      if ( !data.autinc_to && CONSTANT_P (to_addr))
        data.to_addr = copy_addr_to_reg (to_addr);
    }

  if (! SLOW_UNALIGNED_ACCESS (word_mode, align)
      || align > MOVE_MAX * BITS_PER_UNIT || align >= BIGGEST_ALIGNMENT)
    align = MOVE_MAX * BITS_PER_UNIT;

  /* First move what we can in the largest integer mode, then go to
     successively smaller modes.  */

  while (max_size > 1)
    {
      for (tmode = GET_CLASS_NARROWEST_MODE (MODE_INT);
           tmode != VOIDmode; tmode = GET_MODE_WIDER_MODE (tmode))
        if (GET_MODE_SIZE (tmode) < max_size)
          mode = tmode;

      if (mode == VOIDmode)
        break;

      icode = mov_optab->handlers[(int) mode].insn_code;
      if (icode != CODE_FOR_nothing && align >= GET_MODE_ALIGNMENT (mode))
        clear_by_pieces_1 (GEN_FCN (icode), mode, &data);

      max_size = GET_MODE_SIZE (mode);
    }

  /* The code above should have handled everything.  */
  if (data.len != 0)
    abort ();
}

/* Subroutine of clear_by_pieces.  Clear as many bytes as appropriate
   with move instructions for mode MODE.  GENFUN is the gen_... function
   to make a move insn for that mode.  DATA has all the other info.  */

static void
clear_by_pieces_1 (genfun, mode, data)
     rtx (*genfun) PARAMS ((rtx, ...));
     enum machine_mode mode;
     struct clear_by_pieces *data;
{
  unsigned int size = GET_MODE_SIZE (mode);
  rtx to1;

  while (data->len >= size)
    {
      if (data->reverse)
        data->offset -= size;

      if (data->autinc_to)
        {
          to1 = gen_rtx_MEM (mode, data->to_addr);
          MEM_COPY_ATTRIBUTES (to1, data->to);
        }
      else 
        to1 = change_address (data->to, mode,
                              plus_constant (data->to_addr, data->offset));

      if (HAVE_PRE_DECREMENT && data->explicit_inc_to < 0)
        emit_insn (gen_add2_insn (data->to_addr, GEN_INT (-size)));

      emit_insn ((*genfun) (to1, const0_rtx));

      if (HAVE_POST_INCREMENT && data->explicit_inc_to > 0)
        emit_insn (gen_add2_insn (data->to_addr, GEN_INT (size)));

      if (! data->reverse)
        data->offset += size;

      data->len -= size;
    }
}
\f
/* Write zeros through the storage of OBJECT.  If OBJECT has BLKmode, SIZE is
   its length in bytes and ALIGN is the maximum alignment we can is has.

   If we call a function that returns the length of the block, return it.  */

rtx
clear_storage (object, size, align)
     rtx object;
     rtx size;
     unsigned int align;
{
#ifdef TARGET_MEM_FUNCTIONS
  static tree fn;
  tree call_expr, arg_list;
#endif
  rtx retval = 0;

  if (GET_MODE (object) == BLKmode)
    {
      object = protect_from_queue (object, 1);
      size = protect_from_queue (size, 0);

      if (GET_CODE (size) == CONST_INT
          && MOVE_BY_PIECES_P (INTVAL (size), align))
        clear_by_pieces (object, INTVAL (size), align);
      else
        {
          /* Try the most limited insn first, because there's no point
             including more than one in the machine description unless
             the more limited one has some advantage.  */

          rtx opalign = GEN_INT (align / BITS_PER_UNIT);
          enum machine_mode mode;

          for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
               mode = GET_MODE_WIDER_MODE (mode))
            {
              enum insn_code code = clrstr_optab[(int) mode];
              insn_operand_predicate_fn pred;

              if (code != CODE_FOR_nothing
                  /* We don't need MODE to be narrower than
                     BITS_PER_HOST_WIDE_INT here because if SIZE is less than
                     the mode mask, as it is returned by the macro, it will
                     definitely be less than the actual mode mask.  */
                  && ((GET_CODE (size) == CONST_INT
                       && ((unsigned HOST_WIDE_INT) INTVAL (size)
                           <= (GET_MODE_MASK (mode) >> 1)))
                      || GET_MODE_BITSIZE (mode) >= BITS_PER_WORD)
                  && ((pred = insn_data[(int) code].operand[0].predicate) == 0
                      || (*pred) (object, BLKmode))
                  && ((pred = insn_data[(int) code].operand[2].predicate) == 0
                      || (*pred) (opalign, VOIDmode)))
                {
                  rtx op1;
                  rtx last = get_last_insn ();
                  rtx pat;

                  op1 = convert_to_mode (mode, size, 1);
                  pred = insn_data[(int) code].operand[1].predicate;
                  if (pred != 0 && ! (*pred) (op1, mode))
                    op1 = copy_to_mode_reg (mode, op1);

                  pat = GEN_FCN ((int) code) (object, op1, opalign);
                  if (pat)
                    {
                      emit_insn (pat);
                      return 0;
                    }
                  else
                    delete_insns_since (last);
                }
            }

          /* OBJECT or SIZE may have been passed through protect_from_queue.

             It is unsafe to save the value generated by protect_from_queue
             and reuse it later.  Consider what happens if emit_queue is
             called before the return value from protect_from_queue is used.

             Expansion of the CALL_EXPR below will call emit_queue before
             we are finished emitting RTL for argument setup.  So if we are
             not careful we could get the wrong value for an argument.

             To avoid this problem we go ahead and emit code to copy OBJECT
             and SIZE into new pseudos.  We can then place those new pseudos
             into an RTL_EXPR and use them later, even after a call to
             emit_queue.

             Note this is not strictly needed for library calls since they
             do not call emit_queue before loading their arguments.  However,
             we may need to have library calls call emit_queue in the future
             since failing to do so could cause problems for targets which
             define SMALL_REGISTER_CLASSES and pass arguments in registers.  */
          object = copy_to_mode_reg (Pmode, XEXP (object, 0));

#ifdef TARGET_MEM_FUNCTIONS
          size = copy_to_mode_reg (TYPE_MODE (sizetype), size);
#else
          size = convert_to_mode (TYPE_MODE (integer_type_node), size,
                                  TREE_UNSIGNED (integer_type_node));
          size = copy_to_mode_reg (TYPE_MODE (integer_type_node), size);
#endif


#ifdef TARGET_MEM_FUNCTIONS
          /* It is incorrect to use the libcall calling conventions to call
             memset in this context.

             This could be a user call to memset and the user may wish to
             examine the return value from memset.

             For targets where libcalls and normal calls have different
             conventions for returning pointers, we could end up generating
              incorrect code. 

             So instead of using a libcall sequence we build up a suitable
             CALL_EXPR and expand the call in the normal fashion.  */
          if (fn == NULL_TREE)
            {
              tree fntype;

              /* This was copied from except.c, I don't know if all this is
                 necessary in this context or not.  */
              fn = get_identifier ("memset");
              push_obstacks_nochange ();
              end_temporary_allocation ();
              fntype = build_pointer_type (void_type_node);
              fntype = build_function_type (fntype, NULL_TREE);
              fn = build_decl (FUNCTION_DECL, fn, fntype);
              ggc_add_tree_root (&fn, 1);
              DECL_EXTERNAL (fn) = 1;
              TREE_PUBLIC (fn) = 1;
              DECL_ARTIFICIAL (fn) = 1;
              make_decl_rtl (fn, NULL_PTR, 1);
              assemble_external (fn);
              pop_obstacks ();
            }

          /* We need to make an argument list for the function call. 

             memset has three arguments, the first is a void * addresses, the
             second a integer with the initialization value, the last is a
             size_t byte count for the copy.  */
          arg_list
            = build_tree_list (NULL_TREE,
                               make_tree (build_pointer_type (void_type_node),
                                          object));
          TREE_CHAIN (arg_list)
            = build_tree_list (NULL_TREE,
                                make_tree (integer_type_node, const0_rtx));
          TREE_CHAIN (TREE_CHAIN (arg_list))
            = build_tree_list (NULL_TREE, make_tree (sizetype, size));
          TREE_CHAIN (TREE_CHAIN (TREE_CHAIN (arg_list))) = NULL_TREE;

          /* Now we have to build up the CALL_EXPR itself.  */
          call_expr = build1 (ADDR_EXPR,
                              build_pointer_type (TREE_TYPE (fn)), fn);
          call_expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
                             call_expr, arg_list, NULL_TREE);
          TREE_SIDE_EFFECTS (call_expr) = 1;

          retval = expand_expr (call_expr, NULL_RTX, VOIDmode, 0);
#else
          emit_library_call (bzero_libfunc, 0,
                             VOIDmode, 2, object, Pmode, size,
                             TYPE_MODE (integer_type_node));
#endif
        }
    }
  else
    emit_move_insn (object, CONST0_RTX (GET_MODE (object)));

  return retval;
}

/* Generate code to copy Y into X.
   Both Y and X must have the same mode, except that
   Y can be a constant with VOIDmode.
   This mode cannot be BLKmode; use emit_block_move for that.

   Return the last instruction emitted.  */

rtx
emit_move_insn (x, y)
     rtx x, y;
{
  enum machine_mode mode = GET_MODE (x);

  x = protect_from_queue (x, 1);
  y = protect_from_queue (y, 0);

  if (mode == BLKmode || (GET_MODE (y) != mode && GET_MODE (y) != VOIDmode))
    abort ();

  /* Never force constant_p_rtx to memory.  */
  if (GET_CODE (y) == CONSTANT_P_RTX)
    ;
  else if (CONSTANT_P (y) && ! LEGITIMATE_CONSTANT_P (y))
    y = force_const_mem (mode, y);

  /* If X or Y are memory references, verify that their addresses are valid
     for the machine.  */
  if (GET_CODE (x) == MEM
      && ((! memory_address_p (GET_MODE (x), XEXP (x, 0))
           && ! push_operand (x, GET_MODE (x)))
          || (flag_force_addr
              && CONSTANT_ADDRESS_P (XEXP (x, 0)))))
    x = change_address (x, VOIDmode, XEXP (x, 0));

  if (GET_CODE (y) == MEM
      && (! memory_address_p (GET_MODE (y), XEXP (y, 0))
          || (flag_force_addr
              && CONSTANT_ADDRESS_P (XEXP (y, 0)))))
    y = change_address (y, VOIDmode, XEXP (y, 0));

  if (mode == BLKmode)
    abort ();

  return emit_move_insn_1 (x, y);
}

/* Low level part of emit_move_insn.
   Called just like emit_move_insn, but assumes X and Y
   are basically valid.  */

rtx
emit_move_insn_1 (x, y)
     rtx x, y;
{
  enum machine_mode mode = GET_MODE (x);
  enum machine_mode submode;
  enum mode_class class = GET_MODE_CLASS (mode);
  unsigned int i;

  if (mode >= MAX_MACHINE_MODE)
      abort ();

  if (mov_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing)
    return
      emit_insn (GEN_FCN (mov_optab->handlers[(int) mode].insn_code) (x, y));

  /* Expand complex moves by moving real part and imag part, if possible.  */
  else if ((class == MODE_COMPLEX_FLOAT || class == MODE_COMPLEX_INT)
           && BLKmode != (submode = mode_for_size ((GET_MODE_UNIT_SIZE (mode)
                                                    * BITS_PER_UNIT),
                                                   (class == MODE_COMPLEX_INT
                                                    ? MODE_INT : MODE_FLOAT),
                                                   0))
           && (mov_optab->handlers[(int) submode].insn_code
               != CODE_FOR_nothing))
    {
      /* Don't split destination if it is a stack push.  */
      int stack = push_operand (x, GET_MODE (x));

      /* If this is a stack, push the highpart first, so it
         will be in the argument order.

         In that case, change_address is used only to convert
         the mode, not to change the address.  */
      if (stack)
        {
          /* Note that the real part always precedes the imag part in memory
             regardless of machine's endianness.  */
#ifdef STACK_GROWS_DOWNWARD
          emit_insn (GEN_FCN (mov_optab->handlers[(int) submode].insn_code)
                     (gen_rtx_MEM (submode, XEXP (x, 0)),
                      gen_imagpart (submode, y)));
          emit_insn (GEN_FCN (mov_optab->handlers[(int) submode].insn_code)
                     (gen_rtx_MEM (submode, XEXP (x, 0)),
                      gen_realpart (submode, y)));
#else
          emit_insn (GEN_FCN (mov_optab->handlers[(int) submode].insn_code)
                     (gen_rtx_MEM (submode, XEXP (x, 0)),
                      gen_realpart (submode, y)));
          emit_insn (GEN_FCN (mov_optab->handlers[(int) submode].insn_code)
                     (gen_rtx_MEM (submode, XEXP (x, 0)),
                      gen_imagpart (submode, y)));
#endif
        }
      else
        {
          rtx realpart_x, realpart_y;
          rtx imagpart_x, imagpart_y;

          /* If this is a complex value with each part being smaller than a
             word, the usual calling sequence will likely pack the pieces into
             a single register.  Unfortunately, SUBREG of hard registers only
             deals in terms of words, so we have a problem converting input
             arguments to the CONCAT of two registers that is used elsewhere
             for complex values.  If this is before reload, we can copy it into
             memory and reload.  FIXME, we should see about using extract and
             insert on integer registers, but complex short and complex char
             variables should be rarely used.  */
          if (GET_MODE_BITSIZE (mode) < 2*BITS_PER_WORD
              && (reload_in_progress | reload_completed) == 0)
            {
              int packed_dest_p = (REG_P (x) && REGNO (x) < FIRST_PSEUDO_REGISTER);
              int packed_src_p  = (REG_P (y) && REGNO (y) < FIRST_PSEUDO_REGISTER);

              if (packed_dest_p || packed_src_p)
                {
                  enum mode_class reg_class = ((class == MODE_COMPLEX_FLOAT)
                                               ? MODE_FLOAT : MODE_INT);

                  enum machine_mode reg_mode = 
                    mode_for_size (GET_MODE_BITSIZE (mode), reg_class, 1);

                  if (reg_mode != BLKmode)
                    {
                      rtx mem = assign_stack_temp (reg_mode,
                                                   GET_MODE_SIZE (mode), 0);

                      rtx cmem = change_address (mem, mode, NULL_RTX);

                      cfun->cannot_inline = N_("function using short complex types cannot be inline");

                      if (packed_dest_p)
                        {
                          rtx sreg = gen_rtx_SUBREG (reg_mode, x, 0);
                          emit_move_insn_1 (cmem, y);
                          return emit_move_insn_1 (sreg, mem);
                        }
                      else
                        {
                          rtx sreg = gen_rtx_SUBREG (reg_mode, y, 0);
                          emit_move_insn_1 (mem, sreg);
                          return emit_move_insn_1 (x, cmem);
                        }
                    }
                }
            }

          realpart_x = gen_realpart (submode, x);
          realpart_y = gen_realpart (submode, y);
          imagpart_x = gen_imagpart (submode, x);
          imagpart_y = gen_imagpart (submode, y);

          /* Show the output dies here.  This is necessary for SUBREGs
             of pseudos since we cannot track their lifetimes correctly;
             hard regs shouldn't appear here except as return values.
             We never want to emit such a clobber after reload.  */
          if (x != y
              && ! (reload_in_progress || reload_completed)
              && (GET_CODE (realpart_x) == SUBREG
                  || GET_CODE (imagpart_x) == SUBREG))
            {
              emit_insn (gen_rtx_CLOBBER (VOIDmode, x));
            }

          emit_insn (GEN_FCN (mov_optab->handlers[(int) submode].insn_code)
                     (realpart_x, realpart_y));
          emit_insn (GEN_FCN (mov_optab->handlers[(int) submode].insn_code)
                     (imagpart_x, imagpart_y));
        }

      return get_last_insn ();
    }

  /* This will handle any multi-word mode that lacks a move_insn pattern.
     However, you will get better code if you define such patterns,
     even if they must turn into multiple assembler instructions.  */
  else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
    {
      rtx last_insn = 0;
      rtx seq, inner;
      int need_clobber;
      
#ifdef PUSH_ROUNDING

      /* If X is a push on the stack, do the push now and replace
         X with a reference to the stack pointer.  */
      if (push_operand (x, GET_MODE (x)))
        {
          anti_adjust_stack (GEN_INT (GET_MODE_SIZE (GET_MODE (x))));
          x = change_address (x, VOIDmode, stack_pointer_rtx);
        }
#endif
                             
      /* If we are in reload, see if either operand is a MEM whose address
         is scheduled for replacement.  */
      if (reload_in_progress && GET_CODE (x) == MEM
          && (inner = find_replacement (&XEXP (x, 0))) != XEXP (x, 0))
        {
          rtx new = gen_rtx_MEM (GET_MODE (x), inner);

          MEM_COPY_ATTRIBUTES (new, x);
          x = new;
        }
      if (reload_in_progress && GET_CODE (y) == MEM
          && (inner = find_replacement (&XEXP (y, 0))) != XEXP (y, 0))
        {
          rtx new = gen_rtx_MEM (GET_MODE (y), inner);

          MEM_COPY_ATTRIBUTES (new, y);
          y = new;
        }

      start_sequence ();

      need_clobber = 0;
      for (i = 0;
           i < (GET_MODE_SIZE (mode)  + (UNITS_PER_WORD - 1)) / UNITS_PER_WORD;
           i++)
        {
          rtx xpart = operand_subword (x, i, 1, mode);
          rtx ypart = operand_subword (y, i, 1, mode);

          /* If we can't get a part of Y, put Y into memory if it is a
             constant.  Otherwise, force it into a register.  If we still
             can't get a part of Y, abort.  */
          if (ypart == 0 && CONSTANT_P (y))
            {
              y = force_const_mem (mode, y);
              ypart = operand_subword (y, i, 1, mode);
            }
          else if (ypart == 0)
            ypart = operand_subword_force (y, i, mode);

          if (xpart == 0 || ypart == 0)
            abort ();

          need_clobber |= (GET_CODE (xpart) == SUBREG);

          last_insn = emit_move_insn (xpart, ypart);
        }

      seq = gen_sequence ();
      end_sequence ();

      /* Show the output dies here.  This is necessary for SUBREGs
         of pseudos since we cannot track their lifetimes correctly;
         hard regs shouldn't appear here except as return values.
         We never want to emit such a clobber after reload.  */
      if (x != y
          && ! (reload_in_progress || reload_completed)
          && need_clobber != 0)
        {
          emit_insn (gen_rtx_CLOBBER (VOIDmode, x));
        }

      emit_insn (seq);

      return last_insn;
    }
  else
    abort ();
}
\f
/* Pushing data onto the stack.  */

/* Push a block of length SIZE (perhaps variable)
   and return an rtx to address the beginning of the block.
   Note that it is not possible for the value returned to be a QUEUED.
   The value may be virtual_outgoing_args_rtx.

   EXTRA is the number of bytes of padding to push in addition to SIZE.
   BELOW nonzero means this padding comes at low addresses;
   otherwise, the padding comes at high addresses.  */

rtx
push_block (size, extra, below)
     rtx size;
     int extra, below;
{
  register rtx temp;

  size = convert_modes (Pmode, ptr_mode, size, 1);
  if (CONSTANT_P (size))
    anti_adjust_stack (plus_constant (size, extra));
  else if (GET_CODE (size) == REG && extra == 0)
    anti_adjust_stack (size);
  else
    {
      temp = copy_to_mode_reg (Pmode, size);
      if (extra != 0)
        temp = expand_binop (Pmode, add_optab, temp, GEN_INT (extra),
                             temp, 0, OPTAB_LIB_WIDEN);
      anti_adjust_stack (temp);
    }

#ifndef STACK_GROWS_DOWNWARD
#ifdef ARGS_GROW_DOWNWARD
  if (!ACCUMULATE_OUTGOING_ARGS)
#else
  if (0)
#endif
#else
  if (1)
#endif
    {
      /* Return the lowest stack address when STACK or ARGS grow downward and
         we are not aaccumulating outgoing arguments (the c4x port uses such
         conventions).  */
      temp = virtual_outgoing_args_rtx;
      if (extra != 0 && below)
        temp = plus_constant (temp, extra);
    }
  else
    {
      if (GET_CODE (size) == CONST_INT)
        temp = plus_constant (virtual_outgoing_args_rtx,
                              - INTVAL (size) - (below ? 0 : extra));
      else if (extra != 0 && !below)
        temp = gen_rtx_PLUS (Pmode, virtual_outgoing_args_rtx,
                             negate_rtx (Pmode, plus_constant (size, extra)));
      else
        temp = gen_rtx_PLUS (Pmode, virtual_outgoing_args_rtx,
                             negate_rtx (Pmode, size));
    }

  return memory_address (GET_CLASS_NARROWEST_MODE (MODE_INT), temp);
}

rtx
gen_push_operand ()
{
  return gen_rtx_fmt_e (STACK_PUSH_CODE, Pmode, stack_pointer_rtx);
}

/* Return an rtx for the address of the beginning of a as-if-it-was-pushed
   block of SIZE bytes.  */

static rtx
get_push_address (size)
        int size;
{
  register rtx temp;

  if (STACK_PUSH_CODE == POST_DEC)
    temp = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (size));
  else if (STACK_PUSH_CODE == POST_INC)
    temp = gen_rtx_MINUS (Pmode, stack_pointer_rtx, GEN_INT (size));
  else
    temp = stack_pointer_rtx;

  return copy_to_reg (temp);
}

/* Generate code to push X onto the stack, assuming it has mode MODE and
   type TYPE.
   MODE is redundant except when X is a CONST_INT (since they don't
   carry mode info).
   SIZE is an rtx for the size of data to be copied (in bytes),
   needed only if X is BLKmode.

   ALIGN is maximum alignment we can assume.

   If PARTIAL and REG are both nonzero, then copy that many of the first
   words of X into registers starting with REG, and push the rest of X.
   The amount of space pushed is decreased by PARTIAL words,
   rounded *down* to a multiple of PARM_BOUNDARY.
   REG must be a hard register in this case.
   If REG is zero but PARTIAL is not, take any all others actions for an
   argument partially in registers, but do not actually load any
   registers.

   EXTRA is the amount in bytes of extra space to leave next to this arg.
   This is ignored if an argument block has already been allocated.

   On a machine that lacks real push insns, ARGS_ADDR is the address of
   the bottom of the argument block for this call.  We use indexing off there
   to store the arg.  On machines with push insns, ARGS_ADDR is 0 when a
   argument block has not been preallocated.

   ARGS_SO_FAR is the size of args previously pushed for this call.

   REG_PARM_STACK_SPACE is nonzero if functions require stack space
   for arguments passed in registers.  If nonzero, it will be the number
   of bytes required.  */

void
emit_push_insn (x, mode, type, size, align, partial, reg, extra,
                args_addr, args_so_far, reg_parm_stack_space,
                alignment_pad)
     register rtx x;
     enum machine_mode mode;
     tree type;
     rtx size;
     unsigned int align;
     int partial;
     rtx reg;
     int extra;
     rtx args_addr;
     rtx args_so_far;
     int reg_parm_stack_space;
     rtx alignment_pad;
{
  rtx xinner;
  enum direction stack_direction
#ifdef STACK_GROWS_DOWNWARD
    = downward;
#else
    = upward;
#endif

  /* Decide where to pad the argument: `downward' for below,
     `upward' for above, or `none' for don't pad it.
     Default is below for small data on big-endian machines; else above.  */
  enum direction where_pad = FUNCTION_ARG_PADDING (mode, type);

  /* Invert direction if stack is post-update.  */
  if (STACK_PUSH_CODE == POST_INC || STACK_PUSH_CODE == POST_DEC)
    if (where_pad != none)
      where_pad = (where_pad == downward ? upward : downward);

  xinner = x = protect_from_queue (x, 0);

  if (mode == BLKmode)
    {
      /* Copy a block into the stack, entirely or partially.  */

      register rtx temp;
      int used = partial * UNITS_PER_WORD;
      int offset = used % (PARM_BOUNDARY / BITS_PER_UNIT);
      int skip;
      
      if (size == 0)
        abort ();

      used -= offset;

      /* USED is now the # of bytes we need not copy to the stack
         because registers will take care of them.  */

      if (partial != 0)
        xinner = change_address (xinner, BLKmode,
                                 plus_constant (XEXP (xinner, 0), used));

      /* If the partial register-part of the arg counts in its stack size,
         skip the part of stack space corresponding to the registers.
         Otherwise, start copying to the beginning of the stack space,
         by setting SKIP to 0.  */
      skip = (reg_parm_stack_space == 0) ? 0 : used;

#ifdef PUSH_ROUNDING
      /* Do it with several push insns if that doesn't take lots of insns
         and if there is no difficulty with push insns that skip bytes
         on the stack for alignment purposes.  */
      if (args_addr == 0
          && PUSH_ARGS
          && GET_CODE (size) == CONST_INT
          && skip == 0
          && (MOVE_BY_PIECES_P ((unsigned) INTVAL (size) - used, align))
          /* Here we avoid the case of a structure whose weak alignment
             forces many pushes of a small amount of data,
             and such small pushes do rounding that causes trouble.  */
          && ((! SLOW_UNALIGNED_ACCESS (word_mode, align))
              || align >= BIGGEST_ALIGNMENT
              || PUSH_ROUNDING (align) == align)
          && PUSH_ROUNDING (INTVAL (size)) == INTVAL (size))
        {
          /* Push padding now if padding above and stack grows down,
             or if padding below and stack grows up.
             But if space already allocated, this has already been done.  */
          if (extra && args_addr == 0
              && where_pad != none && where_pad != stack_direction)
            anti_adjust_stack (GEN_INT (extra));

          stack_pointer_delta += INTVAL (size) - used;
          move_by_pieces (gen_rtx_MEM (BLKmode, gen_push_operand ()), xinner,
                          INTVAL (size) - used, align);

          if (current_function_check_memory_usage && ! in_check_memory_usage)
            {
              rtx temp;
              
              in_check_memory_usage = 1;
              temp = get_push_address (INTVAL(size) - used);
              if (GET_CODE (x) == MEM && type && AGGREGATE_TYPE_P (type))
                emit_library_call (chkr_copy_bitmap_libfunc, 1, VOIDmode, 3,
                                   temp, Pmode,
                                   XEXP (xinner, 0), Pmode,
                                   GEN_INT (INTVAL(size) - used),
                                   TYPE_MODE (sizetype));
              else
                emit_library_call (chkr_set_right_libfunc, 1, VOIDmode, 3,
                                   temp, Pmode,
                                   GEN_INT (INTVAL(size) - used),
                                   TYPE_MODE (sizetype),
                                   GEN_INT (MEMORY_USE_RW),
                                   TYPE_MODE (integer_type_node));
              in_check_memory_usage = 0;
            }
        }
      else
#endif /* PUSH_ROUNDING */
        {
          rtx target;

          /* Otherwise make space on the stack and copy the data
             to the address of that space.  */

          /* Deduct words put into registers from the size we must copy.  */
          if (partial != 0)
            {
              if (GET_CODE (size) == CONST_INT)
                size = GEN_INT (INTVAL (size) - used);
              else
                size = expand_binop (GET_MODE (size), sub_optab, size,
                                     GEN_INT (used), NULL_RTX, 0,
                                     OPTAB_LIB_WIDEN);
            }

          /* Get the address of the stack space.
             In this case, we do not deal with EXTRA separately.
             A single stack adjust will do.  */
          if (! args_addr)
            {
              temp = push_block (size, extra, where_pad == downward);
              extra = 0;
            }
          else if (GET_CODE (args_so_far) == CONST_INT)
            temp = memory_address (BLKmode,
                                   plus_constant (args_addr,
                                                  skip + INTVAL (args_so_far)));
          else
            temp = memory_address (BLKmode,
                                   plus_constant (gen_rtx_PLUS (Pmode,
                                                                args_addr,
                                                                args_so_far),
                                                  skip));
          if (current_function_check_memory_usage && ! in_check_memory_usage)
            {
              in_check_memory_usage = 1;
              target = copy_to_reg (temp);
              if (GET_CODE (x) == MEM && type && AGGREGATE_TYPE_P (type))
                emit_library_call (chkr_copy_bitmap_libfunc, 1, VOIDmode, 3,
                                   target, Pmode,
                                   XEXP (xinner, 0), Pmode,
                                   size, TYPE_MODE (sizetype));
              else
                emit_library_call (chkr_set_right_libfunc, 1, VOIDmode, 3,
                                   target, Pmode,
                                   size, TYPE_MODE (sizetype),
                                   GEN_INT (MEMORY_USE_RW),
                                   TYPE_MODE (integer_type_node));
              in_check_memory_usage = 0;
            }

            target = gen_rtx_MEM (BLKmode, temp);

            if (type != 0)
              {
                set_mem_attributes (target, type, 1);
                /* Function incoming arguments may overlap with sibling call
                   outgoing arguments and we cannot allow reordering of reads
                   from function arguments with stores to outgoing arguments
                   of sibling calls.  */
                MEM_ALIAS_SET (target) = 0;
              }

          /* TEMP is the address of the block.  Copy the data there.  */
          if (GET_CODE (size) == CONST_INT
              && MOVE_BY_PIECES_P ((unsigned) INTVAL (size), align))
            {
              move_by_pieces (target, xinner, INTVAL (size), align);
              goto ret;
            }
          else
            {
              rtx opalign = GEN_INT (align / BITS_PER_UNIT);
              enum machine_mode mode;

              for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT);
                   mode != VOIDmode;
                   mode = GET_MODE_WIDER_MODE (mode))
                {
                  enum insn_code code = movstr_optab[(int) mode];
                  insn_operand_predicate_fn pred;

                  if (code != CODE_FOR_nothing
                      && ((GET_CODE (size) == CONST_INT
                           && ((unsigned HOST_WIDE_INT) INTVAL (size)
                               <= (GET_MODE_MASK (mode) >> 1)))
                          || GET_MODE_BITSIZE (mode) >= BITS_PER_WORD)
                      && (!(pred = insn_data[(int) code].operand[0].predicate)
                          || ((*pred) (target, BLKmode)))
                      && (!(pred = insn_data[(int) code].operand[1].predicate)
                          || ((*pred) (xinner, BLKmode)))
                      && (!(pred = insn_data[(int) code].operand[3].predicate)
                          || ((*pred) (opalign, VOIDmode))))
                    {
                      rtx op2 = convert_to_mode (mode, size, 1);
                      rtx last = get_last_insn ();
                      rtx pat;

                      pred = insn_data[(int) code].operand[2].predicate;
                      if (pred != 0 && ! (*pred) (op2, mode))
                        op2 = copy_to_mode_reg (mode, op2);

                      pat = GEN_FCN ((int) code) (target, xinner,
                                                  op2, opalign);
                      if (pat)
                        {
                          emit_insn (pat);
                          goto ret;
                        }
                      else
                        delete_insns_since (last);
                    }
                }
            }

          if (!ACCUMULATE_OUTGOING_ARGS)
            {
              /* If the source is referenced relative to the stack pointer,
                 copy it to another register to stabilize it.  We do not need
                 to do this if we know that we won't be changing sp.  */

              if (reg_mentioned_p (virtual_stack_dynamic_rtx, temp)
                  || reg_mentioned_p (virtual_outgoing_args_rtx, temp))
                temp = copy_to_reg (temp);
            }

          /* Make inhibit_defer_pop nonzero around the library call
             to force it to pop the bcopy-arguments right away.  */
          NO_DEFER_POP;
#ifdef TARGET_MEM_FUNCTIONS
          emit_library_call (memcpy_libfunc, 0,
                             VOIDmode, 3, temp, Pmode, XEXP (xinner, 0), Pmode,
                             convert_to_mode (TYPE_MODE (sizetype),
                                              size, TREE_UNSIGNED (sizetype)),
                             TYPE_MODE (sizetype));
#else
          emit_library_call (bcopy_libfunc, 0,
                             VOIDmode, 3, XEXP (xinner, 0), Pmode, temp, Pmode,
                             convert_to_mode (TYPE_MODE (integer_type_node),
                                              size,
                                              TREE_UNSIGNED (integer_type_node)),
                             TYPE_MODE (integer_type_node));
#endif
          OK_DEFER_POP;
        }
    }
  else if (partial > 0)
    {
      /* Scalar partly in registers.  */

      int size = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
      int i;
      int not_stack;
      /* # words of start of argument
         that we must make space for but need not store.  */
      int offset = partial % (PARM_BOUNDARY / BITS_PER_WORD);
      int args_offset = INTVAL (args_so_far);
      int skip;

      /* Push padding now if padding above and stack grows down,
         or if padding below and stack grows up.
         But if space already allocated, this has already been done.  */
      if (extra && args_addr == 0
          && where_pad != none && where_pad != stack_direction)
        anti_adjust_stack (GEN_INT (extra));

      /* If we make space by pushing it, we might as well push
         the real data.  Otherwise, we can leave OFFSET nonzero
         and leave the space uninitialized.  */
      if (args_addr == 0)
        offset = 0;

      /* Now NOT_STACK gets the number of words that we don't need to
         allocate on the stack.  */
      not_stack = partial - offset;

      /* If the partial register-part of the arg counts in its stack size,
         skip the part of stack space corresponding to the registers.
         Otherwise, start copying to the beginning of the stack space,
         by setting SKIP to 0.  */
      skip = (reg_parm_stack_space == 0) ? 0 : not_stack;

      if (CONSTANT_P (x) && ! LEGITIMATE_CONSTANT_P (x))
        x = validize_mem (force_const_mem (mode, x));

      /* If X is a hard register in a non-integer mode, copy it into a pseudo;
         SUBREGs of such registers are not allowed.  */
      if ((GET_CODE (x) == REG && REGNO (x) < FIRST_PSEUDO_REGISTER
           && GET_MODE_CLASS (GET_MODE (x)) != MODE_INT))
        x = copy_to_reg (x);

      /* Loop over all the words allocated on the stack for this arg.  */
      /* We can do it by words, because any scalar bigger than a word
         has a size a multiple of a word.  */
#ifndef PUSH_ARGS_REVERSED
      for (i = not_stack; i < size; i++)
#else
      for (i = size - 1; i >= not_stack; i--)
#endif
        if (i >= not_stack + offset)
          emit_push_insn (operand_subword_force (x, i, mode),
                          word_mode, NULL_TREE, NULL_RTX, align, 0, NULL_RTX,
                          0, args_addr,
                          GEN_INT (args_offset + ((i - not_stack + skip)
                                                  * UNITS_PER_WORD)),
                          reg_parm_stack_space, alignment_pad);
    }
  else
    {
      rtx addr;
      rtx target = NULL_RTX;
      rtx dest;

      /* Push padding now if padding above and stack grows down,
         or if padding below and stack grows up.
         But if space already allocated, this has already been done.  */
      if (extra && args_addr == 0
          && where_pad != none && where_pad != stack_direction)
        anti_adjust_stack (GEN_INT (extra));

#ifdef PUSH_ROUNDING
      if (args_addr == 0 && PUSH_ARGS)
        {
          addr = gen_push_operand ();
          stack_pointer_delta += PUSH_ROUNDING (GET_MODE_SIZE (mode));
        }
      else
#endif
        {
          if (GET_CODE (args_so_far) == CONST_INT)
            addr
              = memory_address (mode,
                                plus_constant (args_addr, 
                                               INTVAL (args_so_far)));
          else
            addr = memory_address (mode, gen_rtx_PLUS (Pmode, args_addr,
                                                       args_so_far));
          target = addr;
        }

      dest = gen_rtx_MEM (mode, addr);
      if (type != 0)
        {
          set_mem_attributes (dest, type, 1);
          /* Function incoming arguments may overlap with sibling call
             outgoing arguments and we cannot allow reordering of reads
             from function arguments with stores to outgoing arguments
             of sibling calls.  */
          MEM_ALIAS_SET (dest) = 0;
        }

      emit_move_insn (dest, x);

      if (current_function_check_memory_usage && ! in_check_memory_usage)
        {
          in_check_memory_usage = 1;
          if (target == 0)
            target = get_push_address (GET_MODE_SIZE (mode));

          if (GET_CODE (x) == MEM && type && AGGREGATE_TYPE_P (type))
            emit_library_call (chkr_copy_bitmap_libfunc, 1, VOIDmode, 3,
                               target, Pmode,
                               XEXP (x, 0), Pmode,
                               GEN_INT (GET_MODE_SIZE (mode)),
                               TYPE_MODE (sizetype));
          else
            emit_library_call (chkr_set_right_libfunc, 1, VOIDmode, 3,
                               target, Pmode,
                               GEN_INT (GET_MODE_SIZE (mode)),
                               TYPE_MODE (sizetype),
                               GEN_INT (MEMORY_USE_RW),
                               TYPE_MODE (integer_type_node));
          in_check_memory_usage = 0;
        }
    }

 ret:
  /* If part should go in registers, copy that part
     into the appropriate registers.  Do this now, at the end,
     since mem-to-mem copies above may do function calls.  */
  if (partial > 0 && reg != 0)
    {
      /* Handle calls that pass values in multiple non-contiguous locations.
         The Irix 6 ABI has examples of this.  */
      if (GET_CODE (reg) == PARALLEL)
        emit_group_load (reg, x, -1, align);  /* ??? size? */
      else
        move_block_to_reg (REGNO (reg), x, partial, mode);
    }

  if (extra && args_addr == 0 && where_pad == stack_direction)
    anti_adjust_stack (GEN_INT (extra));
 
  if (alignment_pad && args_addr == 0)
    anti_adjust_stack (alignment_pad);
}
\f
/* Return X if X can be used as a subtarget in a sequence of arithmetic
   operations.  */

static rtx
get_subtarget (x)
     rtx x;
{
  return ((x == 0
           /* Only registers can be subtargets.  */
           || GET_CODE (x) != REG
           /* If the register is readonly, it can't be set more than once.  */
           || RTX_UNCHANGING_P (x)
           /* Don't use hard regs to avoid extending their life.  */
           || REGNO (x) < FIRST_PSEUDO_REGISTER
           /* Avoid subtargets inside loops,
              since they hide some invariant expressions.  */
           || preserve_subexpressions_p ())
          ? 0 : x);
}

/* Expand an assignment that stores the value of FROM into TO.
   If WANT_VALUE is nonzero, return an rtx for the value of TO.
   (This may contain a QUEUED rtx;
   if the value is constant, this rtx is a constant.)
   Otherwise, the returned value is NULL_RTX.

   SUGGEST_REG is no longer actually used.
   It used to mean, copy the value through a register
   and return that register, if that is possible.
   We now use WANT_VALUE to decide whether to do this.  */

rtx
expand_assignment (to, from, want_value, suggest_reg)
     tree to, from;
     int want_value;
     int suggest_reg ATTRIBUTE_UNUSED;
{
  register rtx to_rtx = 0;
  rtx result;

  /* Don't crash if the lhs of the assignment was erroneous.  */

  if (TREE_CODE (to) == ERROR_MARK)
    {
      result = expand_expr (from, NULL_RTX, VOIDmode, 0);
      return want_value ? result : NULL_RTX;
    }

  /* Assignment of a structure component needs special treatment
     if the structure component's rtx is not simply a MEM.
     Assignment of an array element at a constant index, and assignment of
     an array element in an unaligned packed structure field, has the same
     problem.  */

  if (TREE_CODE (to) == COMPONENT_REF || TREE_CODE (to) == BIT_FIELD_REF
      || TREE_CODE (to) == ARRAY_REF)
    {
      enum machine_mode mode1;
      HOST_WIDE_INT bitsize, bitpos;
      tree offset;
      int unsignedp;
      int volatilep = 0;
      tree tem;
      unsigned int alignment;

      push_temp_slots ();
      tem = get_inner_reference (to, &bitsize, &bitpos, &offset, &mode1,
                                 &unsignedp, &volatilep, &alignment);

      /* If we are going to use store_bit_field and extract_bit_field,
         make sure to_rtx will be safe for multiple use.  */

      if (mode1 == VOIDmode && want_value)
        tem = stabilize_reference (tem);

      to_rtx = expand_expr (tem, NULL_RTX, VOIDmode, EXPAND_MEMORY_USE_DONT);
      if (offset != 0)
        {
          rtx offset_rtx = expand_expr (offset, NULL_RTX, VOIDmode, 0);

          if (GET_CODE (to_rtx) != MEM)
            abort ();

          if (GET_MODE (offset_rtx) != ptr_mode)
            {
#ifdef POINTERS_EXTEND_UNSIGNED
              offset_rtx = convert_memory_address (ptr_mode, offset_rtx);
#else
              offset_rtx = convert_to_mode (ptr_mode, offset_rtx, 0);
#endif
            }

          /* A constant address in TO_RTX can have VOIDmode, we must not try
             to call force_reg for that case.  Avoid that case.  */
          if (GET_CODE (to_rtx) == MEM
              && GET_MODE (to_rtx) == BLKmode
              && GET_MODE (XEXP (to_rtx, 0)) != VOIDmode
              && bitsize
              && (bitpos % bitsize) == 0 
              && (bitsize % GET_MODE_ALIGNMENT (mode1)) == 0
              && alignment == GET_MODE_ALIGNMENT (mode1))
            {
              rtx temp = change_address (to_rtx, mode1,
                                         plus_constant (XEXP (to_rtx, 0),
                                                        (bitpos /
                                                         BITS_PER_UNIT)));
              if (GET_CODE (XEXP (temp, 0)) == REG)
                to_rtx = temp;
              else
                to_rtx = change_address (to_rtx, mode1,
                                         force_reg (GET_MODE (XEXP (temp, 0)),
                                                    XEXP (temp, 0)));
              bitpos = 0;
            }

          to_rtx = change_address (to_rtx, VOIDmode,
                                   gen_rtx_PLUS (ptr_mode, XEXP (to_rtx, 0),
                                                 force_reg (ptr_mode,
                                                            offset_rtx)));
        }

      if (volatilep)
        {
          if (GET_CODE (to_rtx) == MEM)
            {
              /* When the offset is zero, to_rtx is the address of the
                 structure we are storing into, and hence may be shared.
                 We must make a new MEM before setting the volatile bit.  */
              if (offset == 0)
                to_rtx = copy_rtx (to_rtx);

              MEM_VOLATILE_P (to_rtx) = 1;
            }
#if 0  /* This was turned off because, when a field is volatile
          in an object which is not volatile, the object may be in a register,
          and then we would abort over here.  */
          else
            abort ();
#endif
        }

      if (TREE_CODE (to) == COMPONENT_REF
          && TREE_READONLY (TREE_OPERAND (to, 1)))
        {
          if (offset == 0)
            to_rtx = copy_rtx (to_rtx);

          RTX_UNCHANGING_P (to_rtx) = 1;
        }

      /* Check the access.  */
      if (current_function_check_memory_usage && GET_CODE (to_rtx) == MEM)
        {
          rtx to_addr;
          int size;
          int best_mode_size;
          enum machine_mode best_mode;

          best_mode = get_best_mode (bitsize, bitpos,
                                     TYPE_ALIGN (TREE_TYPE (tem)),
                                     mode1, volatilep);
          if (best_mode == VOIDmode)
            best_mode = QImode;

          best_mode_size = GET_MODE_BITSIZE (best_mode);
          to_addr = plus_constant (XEXP (to_rtx, 0), (bitpos / BITS_PER_UNIT));
          size = CEIL ((bitpos % best_mode_size) + bitsize, best_mode_size);
          size *= GET_MODE_SIZE (best_mode);

          /* Check the access right of the pointer.  */
          in_check_memory_usage = 1;
          if (size)
            emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                               to_addr, Pmode,
                               GEN_INT (size), TYPE_MODE (sizetype),
                               GEN_INT (MEMORY_USE_WO),
                               TYPE_MODE (integer_type_node));
          in_check_memory_usage = 0;
        }

      /* If this is a varying-length object, we must get the address of
         the source and do an explicit block move.  */
      if (bitsize < 0)
        {
          unsigned int from_align;
          rtx from_rtx = expand_expr_unaligned (from, &from_align);
          rtx inner_to_rtx
            = change_address (to_rtx, VOIDmode,
                              plus_constant (XEXP (to_rtx, 0),
                                             bitpos / BITS_PER_UNIT));

          emit_block_move (inner_to_rtx, from_rtx, expr_size (from),
                           MIN (alignment, from_align));
          free_temp_slots ();
          pop_temp_slots ();
          return to_rtx;
        }
      else
        {
          result = store_field (to_rtx, bitsize, bitpos, mode1, from,
                                (want_value
                                 /* Spurious cast for HPUX compiler.  */
                                 ? ((enum machine_mode)
                                    TYPE_MODE (TREE_TYPE (to)))
                                 : VOIDmode),
                                unsignedp,
                                alignment,
                                int_size_in_bytes (TREE_TYPE (tem)),
                                get_alias_set (to));

          preserve_temp_slots (result);
          free_temp_slots ();
          pop_temp_slots ();

          /* If the value is meaningful, convert RESULT to the proper mode.
             Otherwise, return nothing.  */
          return (want_value ? convert_modes (TYPE_MODE (TREE_TYPE (to)),
                                              TYPE_MODE (TREE_TYPE (from)),
                                              result,
                                              TREE_UNSIGNED (TREE_TYPE (to)))
                  : NULL_RTX);
        }
    }

  /* If the rhs is a function call and its value is not an aggregate,
     call the function before we start to compute the lhs.
     This is needed for correct code for cases such as
     val = setjmp (buf) on machines where reference to val
     requires loading up part of an address in a separate insn.

     Don't do this if TO is a VAR_DECL or PARM_DECL whose DECL_RTL is REG
     since it might be a promoted variable where the zero- or sign- extension
     needs to be done.  Handling this in the normal way is safe because no
     computation is done before the call.  */
  if (TREE_CODE (from) == CALL_EXPR && ! aggregate_value_p (from)
      && TREE_CODE (TYPE_SIZE (TREE_TYPE (from))) == INTEGER_CST
      && ! ((TREE_CODE (to) == VAR_DECL || TREE_CODE (to) == PARM_DECL)
            && GET_CODE (DECL_RTL (to)) == REG))
    {
      rtx value;

      push_temp_slots ();
      value = expand_expr (from, NULL_RTX, VOIDmode, 0);
      if (to_rtx == 0)
        to_rtx = expand_expr (to, NULL_RTX, VOIDmode, EXPAND_MEMORY_USE_WO);

      /* Handle calls that return values in multiple non-contiguous locations.
         The Irix 6 ABI has examples of this.  */
      if (GET_CODE (to_rtx) == PARALLEL)
        emit_group_load (to_rtx, value, int_size_in_bytes (TREE_TYPE (from)),
                         TYPE_ALIGN (TREE_TYPE (from)));
      else if (GET_MODE (to_rtx) == BLKmode)
        emit_block_move (to_rtx, value, expr_size (from),
                         TYPE_ALIGN (TREE_TYPE (from)));
      else
        {
#ifdef POINTERS_EXTEND_UNSIGNED
          if (TREE_CODE (TREE_TYPE (to)) == REFERENCE_TYPE
             || TREE_CODE (TREE_TYPE (to)) == POINTER_TYPE)
            value = convert_memory_address (GET_MODE (to_rtx), value);
#endif
          emit_move_insn (to_rtx, value);
        }
      preserve_temp_slots (to_rtx);
      free_temp_slots ();
      pop_temp_slots ();
      return want_value ? to_rtx : NULL_RTX;
    }

  /* Ordinary treatment.  Expand TO to get a REG or MEM rtx.
     Don't re-expand if it was expanded already (in COMPONENT_REF case).  */

  if (to_rtx == 0)
    {
      to_rtx = expand_expr (to, NULL_RTX, VOIDmode, EXPAND_MEMORY_USE_WO);
      if (GET_CODE (to_rtx) == MEM)
        MEM_ALIAS_SET (to_rtx) = get_alias_set (to);
    }

  /* Don't move directly into a return register.  */
  if (TREE_CODE (to) == RESULT_DECL
      && (GET_CODE (to_rtx) == REG || GET_CODE (to_rtx) == PARALLEL))
    {
      rtx temp;

      push_temp_slots ();
      temp = expand_expr (from, 0, GET_MODE (to_rtx), 0);

      if (GET_CODE (to_rtx) == PARALLEL)
        emit_group_load (to_rtx, temp, int_size_in_bytes (TREE_TYPE (from)),
                         TYPE_ALIGN (TREE_TYPE (from)));
      else
        emit_move_insn (to_rtx, temp);

      preserve_temp_slots (to_rtx);
      free_temp_slots ();
      pop_temp_slots ();
      return want_value ? to_rtx : NULL_RTX;
    }

  /* In case we are returning the contents of an object which overlaps
     the place the value is being stored, use a safe function when copying
     a value through a pointer into a structure value return block.  */
  if (TREE_CODE (to) == RESULT_DECL && TREE_CODE (from) == INDIRECT_REF
      && current_function_returns_struct
      && !current_function_returns_pcc_struct)
    {
      rtx from_rtx, size;

      push_temp_slots ();
      size = expr_size (from);
      from_rtx = expand_expr (from, NULL_RTX, VOIDmode,
                              EXPAND_MEMORY_USE_DONT);

      /* Copy the rights of the bitmap.  */
      if (current_function_check_memory_usage)
        emit_library_call (chkr_copy_bitmap_libfunc, 1, VOIDmode, 3,
                           XEXP (to_rtx, 0), Pmode,
                           XEXP (from_rtx, 0), Pmode,
                           convert_to_mode (TYPE_MODE (sizetype),
                                            size, TREE_UNSIGNED (sizetype)),
                           TYPE_MODE (sizetype));

#ifdef TARGET_MEM_FUNCTIONS
      emit_library_call (memcpy_libfunc, 0,
                         VOIDmode, 3, XEXP (to_rtx, 0), Pmode,
                         XEXP (from_rtx, 0), Pmode,
                         convert_to_mode (TYPE_MODE (sizetype),
                                          size, TREE_UNSIGNED (sizetype)),
                         TYPE_MODE (sizetype));
#else
      emit_library_call (bcopy_libfunc, 0,
                         VOIDmode, 3, XEXP (from_rtx, 0), Pmode,
                         XEXP (to_rtx, 0), Pmode,
                         convert_to_mode (TYPE_MODE (integer_type_node),
                                          size, TREE_UNSIGNED (integer_type_node)),
                         TYPE_MODE (integer_type_node));
#endif

      preserve_temp_slots (to_rtx);
      free_temp_slots ();
      pop_temp_slots ();
      return want_value ? to_rtx : NULL_RTX;
    }

  /* Compute FROM and store the value in the rtx we got.  */

  push_temp_slots ();
  result = store_expr (from, to_rtx, want_value);
  preserve_temp_slots (result);
  free_temp_slots ();
  pop_temp_slots ();
  return want_value ? result : NULL_RTX;
}

/* Generate code for computing expression EXP,
   and storing the value into TARGET.
   TARGET may contain a QUEUED rtx.

   If WANT_VALUE is nonzero, return a copy of the value
   not in TARGET, so that we can be sure to use the proper
   value in a containing expression even if TARGET has something
   else stored in it.  If possible, we copy the value through a pseudo
   and return that pseudo.  Or, if the value is constant, we try to
   return the constant.  In some cases, we return a pseudo
   copied *from* TARGET.

   If the mode is BLKmode then we may return TARGET itself.
   It turns out that in BLKmode it doesn't cause a problem.
   because C has no operators that could combine two different
   assignments into the same BLKmode object with different values
   with no sequence point.  Will other languages need this to
   be more thorough?

   If WANT_VALUE is 0, we return NULL, to make sure
   to catch quickly any cases where the caller uses the value
   and fails to set WANT_VALUE.  */

rtx
store_expr (exp, target, want_value)
     register tree exp;
     register rtx target;
     int want_value;
{
  register rtx temp;
  int dont_return_target = 0;

  if (TREE_CODE (exp) == COMPOUND_EXPR)
    {
      /* Perform first part of compound expression, then assign from second
         part.  */
      expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
      emit_queue ();
      return store_expr (TREE_OPERAND (exp, 1), target, want_value);
    }
  else if (TREE_CODE (exp) == COND_EXPR && GET_MODE (target) == BLKmode)
    {
      /* For conditional expression, get safe form of the target.  Then
         test the condition, doing the appropriate assignment on either
         side.  This avoids the creation of unnecessary temporaries.
         For non-BLKmode, it is more efficient not to do this.  */

      rtx lab1 = gen_label_rtx (), lab2 = gen_label_rtx ();

      emit_queue ();
      target = protect_from_queue (target, 1);

      do_pending_stack_adjust ();
      NO_DEFER_POP;
      jumpifnot (TREE_OPERAND (exp, 0), lab1);
      start_cleanup_deferral ();
      store_expr (TREE_OPERAND (exp, 1), target, 0);
      end_cleanup_deferral ();
      emit_queue ();
      emit_jump_insn (gen_jump (lab2));
      emit_barrier ();
      emit_label (lab1);
      start_cleanup_deferral ();
      store_expr (TREE_OPERAND (exp, 2), target, 0);
      end_cleanup_deferral ();
      emit_queue ();
      emit_label (lab2);
      OK_DEFER_POP;

      return want_value ? target : NULL_RTX;
    }
  else if (queued_subexp_p (target))
    /* If target contains a postincrement, let's not risk
       using it as the place to generate the rhs.  */
    {
      if (GET_MODE (target) != BLKmode && GET_MODE (target) != VOIDmode)
        {
          /* Expand EXP into a new pseudo.  */
          temp = gen_reg_rtx (GET_MODE (target));
          temp = expand_expr (exp, temp, GET_MODE (target), 0);
        }
      else
        temp = expand_expr (exp, NULL_RTX, GET_MODE (target), 0);

      /* If target is volatile, ANSI requires accessing the value
         *from* the target, if it is accessed.  So make that happen.
         In no case return the target itself.  */
      if (! MEM_VOLATILE_P (target) && want_value)
        dont_return_target = 1;
    }
  else if (want_value && GET_CODE (target) == MEM && ! MEM_VOLATILE_P (target)
           && GET_MODE (target) != BLKmode)
    /* If target is in memory and caller wants value in a register instead,
       arrange that.  Pass TARGET as target for expand_expr so that,
       if EXP is another assignment, WANT_VALUE will be nonzero for it.
       We know expand_expr will not use the target in that case.
       Don't do this if TARGET is volatile because we are supposed
       to write it and then read it.  */
    {
      temp = expand_expr (exp, target, GET_MODE (target), 0);
      if (GET_MODE (temp) != BLKmode && GET_MODE (temp) != VOIDmode)
        temp = copy_to_reg (temp);
      dont_return_target = 1;
    }
  else if (GET_CODE (target) == SUBREG && SUBREG_PROMOTED_VAR_P (target))
    /* If this is an scalar in a register that is stored in a wider mode
       than the declared mode, compute the result into its declared mode
       and then convert to the wider mode.  Our value is the computed
       expression.  */
    {
      /* If we don't want a value, we can do the conversion inside EXP,
         which will often result in some optimizations.  Do the conversion
         in two steps: first change the signedness, if needed, then
         the extend.  But don't do this if the type of EXP is a subtype
         of something else since then the conversion might involve
         more than just converting modes.  */
      if (! want_value && INTEGRAL_TYPE_P (TREE_TYPE (exp))
          && TREE_TYPE (TREE_TYPE (exp)) == 0)
        {
          if (TREE_UNSIGNED (TREE_TYPE (exp))
              != SUBREG_PROMOTED_UNSIGNED_P (target))
            exp
              = convert
                (signed_or_unsigned_type (SUBREG_PROMOTED_UNSIGNED_P (target),
                                          TREE_TYPE (exp)),
                 exp);

          exp = convert (type_for_mode (GET_MODE (SUBREG_REG (target)),
                                        SUBREG_PROMOTED_UNSIGNED_P (target)),
                         exp);
        }
         
      temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);

      /* If TEMP is a volatile MEM and we want a result value, make
         the access now so it gets done only once.  Likewise if
         it contains TARGET.  */
      if (GET_CODE (temp) == MEM && want_value
          && (MEM_VOLATILE_P (temp)
              || reg_mentioned_p (SUBREG_REG (target), XEXP (temp, 0))))
        temp = copy_to_reg (temp);

      /* If TEMP is a VOIDmode constant, use convert_modes to make
         sure that we properly convert it.  */
      if (CONSTANT_P (temp) && GET_MODE (temp) == VOIDmode)
        temp = convert_modes (GET_MODE (SUBREG_REG (target)),
                              TYPE_MODE (TREE_TYPE (exp)), temp,
                              SUBREG_PROMOTED_UNSIGNED_P (target));

      convert_move (SUBREG_REG (target), temp,
                    SUBREG_PROMOTED_UNSIGNED_P (target));

      /* If we promoted a constant, change the mode back down to match
         target.  Otherwise, the caller might get confused by a result whose
         mode is larger than expected.  */

      if (want_value && GET_MODE (temp) != GET_MODE (target)
          && GET_MODE (temp) != VOIDmode)
        {
          temp = gen_rtx_SUBREG (GET_MODE (target), temp, 0);
          SUBREG_PROMOTED_VAR_P (temp) = 1;
          SUBREG_PROMOTED_UNSIGNED_P (temp)
            = SUBREG_PROMOTED_UNSIGNED_P (target);
        }

      return want_value ? temp : NULL_RTX;
    }
  else
    {
      temp = expand_expr (exp, target, GET_MODE (target), 0);
      /* Return TARGET if it's a specified hardware register.
         If TARGET is a volatile mem ref, either return TARGET
         or return a reg copied *from* TARGET; ANSI requires this.

         Otherwise, if TEMP is not TARGET, return TEMP
         if it is constant (for efficiency),
         or if we really want the correct value.  */
      if (!(target && GET_CODE (target) == REG
            && REGNO (target) < FIRST_PSEUDO_REGISTER)
          && !(GET_CODE (target) == MEM && MEM_VOLATILE_P (target))
          && ! rtx_equal_p (temp, target)
          && (CONSTANT_P (temp) || want_value))
        dont_return_target = 1;
    }

  /* If TEMP is a VOIDmode constant and the mode of the type of EXP is not
     the same as that of TARGET, adjust the constant.  This is needed, for
     example, in case it is a CONST_DOUBLE and we want only a word-sized
     value.  */
  if (CONSTANT_P (temp) && GET_MODE (temp) == VOIDmode
      && TREE_CODE (exp) != ERROR_MARK
      && GET_MODE (target) != TYPE_MODE (TREE_TYPE (exp)))
    temp = convert_modes (GET_MODE (target), TYPE_MODE (TREE_TYPE (exp)),
                          temp, TREE_UNSIGNED (TREE_TYPE (exp)));

  if (current_function_check_memory_usage
      && GET_CODE (target) == MEM
      && AGGREGATE_TYPE_P (TREE_TYPE (exp)))
    {
      in_check_memory_usage = 1;
      if (GET_CODE (temp) == MEM)
        emit_library_call (chkr_copy_bitmap_libfunc, 1, VOIDmode, 3,
                           XEXP (target, 0), Pmode,
                           XEXP (temp, 0), Pmode,
                           expr_size (exp), TYPE_MODE (sizetype));
      else
        emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                           XEXP (target, 0), Pmode, 
                           expr_size (exp), TYPE_MODE (sizetype),
                           GEN_INT (MEMORY_USE_WO), 
                           TYPE_MODE (integer_type_node));
      in_check_memory_usage = 0;
    }

  /* If value was not generated in the target, store it there.
     Convert the value to TARGET's type first if nec.  */
  /* If TEMP and TARGET compare equal according to rtx_equal_p, but
     one or both of them are volatile memory refs, we have to distinguish
     two cases:
     - expand_expr has used TARGET.  In this case, we must not generate
       another copy.  This can be detected by TARGET being equal according
       to == .
     - expand_expr has not used TARGET - that means that the source just
       happens to have the same RTX form.  Since temp will have been created
       by expand_expr, it will compare unequal according to == .
       We must generate a copy in this case, to reach the correct number
       of volatile memory references.  */

  if ((! rtx_equal_p (temp, target)
       || (temp != target && (side_effects_p (temp)
                              || side_effects_p (target))))
      && TREE_CODE (exp) != ERROR_MARK)
    {
      target = protect_from_queue (target, 1);
      if (GET_MODE (temp) != GET_MODE (target)
          && GET_MODE (temp) != VOIDmode)
        {
          int unsignedp = TREE_UNSIGNED (TREE_TYPE (exp));
          if (dont_return_target)
            {
              /* In this case, we will return TEMP,
                 so make sure it has the proper mode.
                 But don't forget to store the value into TARGET.  */
              temp = convert_to_mode (GET_MODE (target), temp, unsignedp);
              emit_move_insn (target, temp);
            }
          else
            convert_move (target, temp, unsignedp);
        }

      else if (GET_MODE (temp) == BLKmode && TREE_CODE (exp) == STRING_CST)
        {
          /* Handle copying a string constant into an array.
             The string constant may be shorter than the array.
             So copy just the string's actual length, and clear the rest.  */
          rtx size;
          rtx addr;

          /* Get the size of the data type of the string,
             which is actually the size of the target.  */
          size = expr_size (exp);
          if (GET_CODE (size) == CONST_INT
              && INTVAL (size) < TREE_STRING_LENGTH (exp))
            emit_block_move (target, temp, size, TYPE_ALIGN (TREE_TYPE (exp)));
          else
            {
              /* Compute the size of the data to copy from the string.  */
              tree copy_size
                = size_binop (MIN_EXPR,
                              make_tree (sizetype, size),
                              size_int (TREE_STRING_LENGTH (exp)));
              unsigned int align = TYPE_ALIGN (TREE_TYPE (exp));
              rtx copy_size_rtx = expand_expr (copy_size, NULL_RTX,
                                               VOIDmode, 0);
              rtx label = 0;

              /* Copy that much.  */
              emit_block_move (target, temp, copy_size_rtx,
                               TYPE_ALIGN (TREE_TYPE (exp)));

              /* Figure out how much is left in TARGET that we have to clear.
                 Do all calculations in ptr_mode.  */

              addr = XEXP (target, 0);
              addr = convert_modes (ptr_mode, Pmode, addr, 1);

              if (GET_CODE (copy_size_rtx) == CONST_INT)
                {
                  addr = plus_constant (addr, TREE_STRING_LENGTH (exp));
                  size = plus_constant (size, - TREE_STRING_LENGTH (exp));
                  align = MIN (align, (BITS_PER_UNIT
                                       * (INTVAL (copy_size_rtx)
                                          & - INTVAL (copy_size_rtx))));
                }
              else
                {
                  addr = force_reg (ptr_mode, addr);
                  addr = expand_binop (ptr_mode, add_optab, addr,
                                       copy_size_rtx, NULL_RTX, 0,
                                       OPTAB_LIB_WIDEN);

                  size = expand_binop (ptr_mode, sub_optab, size,
                                       copy_size_rtx, NULL_RTX, 0,
                                       OPTAB_LIB_WIDEN);

                  align = BITS_PER_UNIT;
                  label = gen_label_rtx ();
                  emit_cmp_and_jump_insns (size, const0_rtx, LT, NULL_RTX,
                                           GET_MODE (size), 0, 0, label);
                }
              align = MIN (align, expr_align (copy_size));

              if (size != const0_rtx)
                {
                  rtx dest = gen_rtx_MEM (BLKmode, addr);

                  MEM_COPY_ATTRIBUTES (dest, target);

                  /* Be sure we can write on ADDR.  */
                  in_check_memory_usage = 1;
                  if (current_function_check_memory_usage)
                    emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                                       addr, Pmode,
                                       size, TYPE_MODE (sizetype),
                                       GEN_INT (MEMORY_USE_WO), 
                                       TYPE_MODE (integer_type_node));
                  in_check_memory_usage = 0;
                  clear_storage (dest, size, align);
                }

              if (label)
                emit_label (label);
            }
        }
      /* Handle calls that return values in multiple non-contiguous locations.
         The Irix 6 ABI has examples of this.  */
      else if (GET_CODE (target) == PARALLEL)
        emit_group_load (target, temp, int_size_in_bytes (TREE_TYPE (exp)),
                         TYPE_ALIGN (TREE_TYPE (exp)));
      else if (GET_MODE (temp) == BLKmode)
        emit_block_move (target, temp, expr_size (exp),
                         TYPE_ALIGN (TREE_TYPE (exp)));
      else
        emit_move_insn (target, temp);
    }

  /* If we don't want a value, return NULL_RTX.  */
  if (! want_value)
    return NULL_RTX;

  /* If we are supposed to return TEMP, do so as long as it isn't a MEM.
     ??? The latter test doesn't seem to make sense.  */
  else if (dont_return_target && GET_CODE (temp) != MEM)
    return temp;

  /* Return TARGET itself if it is a hard register.  */
  else if (want_value && GET_MODE (target) != BLKmode
           && ! (GET_CODE (target) == REG
                 && REGNO (target) < FIRST_PSEUDO_REGISTER))
    return copy_to_reg (target);
  
  else
    return target;
}
\f
/* Return 1 if EXP just contains zeros.  */

static int
is_zeros_p (exp)
     tree exp;
{
  tree elt;

  switch (TREE_CODE (exp))
    {
    case CONVERT_EXPR:
    case NOP_EXPR:
    case NON_LVALUE_EXPR:
      return is_zeros_p (TREE_OPERAND (exp, 0));

    case INTEGER_CST:
      return integer_zerop (exp);

    case COMPLEX_CST:
      return
        is_zeros_p (TREE_REALPART (exp)) && is_zeros_p (TREE_IMAGPART (exp));

    case REAL_CST:
      return REAL_VALUES_IDENTICAL (TREE_REAL_CST (exp), dconst0);

    case CONSTRUCTOR:
      if (TREE_TYPE (exp) && TREE_CODE (TREE_TYPE (exp)) == SET_TYPE)
        return CONSTRUCTOR_ELTS (exp) == NULL_TREE;
      for (elt = CONSTRUCTOR_ELTS (exp); elt; elt = TREE_CHAIN (elt))
        if (! is_zeros_p (TREE_VALUE (elt)))
          return 0;

      return 1;
      
    default:
      return 0;
    }
}

/* Return 1 if EXP contains mostly (3/4)  zeros.  */

static int
mostly_zeros_p (exp)
     tree exp;
{
  if (TREE_CODE (exp) == CONSTRUCTOR)
    {
      int elts = 0, zeros = 0;
      tree elt = CONSTRUCTOR_ELTS (exp);
      if (TREE_TYPE (exp) && TREE_CODE (TREE_TYPE (exp)) == SET_TYPE)
        {
          /* If there are no ranges of true bits, it is all zero.  */
          return elt == NULL_TREE;
        }
      for (; elt; elt = TREE_CHAIN (elt))
        {
          /* We do not handle the case where the index is a RANGE_EXPR,
             so the statistic will be somewhat inaccurate.
             We do make a more accurate count in store_constructor itself,
             so since this function is only used for nested array elements,
             this should be close enough.  */
          if (mostly_zeros_p (TREE_VALUE (elt)))
            zeros++;
          elts++;
        }

      return 4 * zeros >= 3 * elts;
    }

  return is_zeros_p (exp);
}
\f
/* Helper function for store_constructor.
   TARGET, BITSIZE, BITPOS, MODE, EXP are as for store_field.
   TYPE is the type of the CONSTRUCTOR, not the element type.
   ALIGN and CLEARED are as for store_constructor.

   This provides a recursive shortcut back to store_constructor when it isn't
   necessary to go through store_field.  This is so that we can pass through
   the cleared field to let store_constructor know that we may not have to
   clear a substructure if the outer structure has already been cleared.  */

static void
store_constructor_field (target, bitsize, bitpos,
                         mode, exp, type, align, cleared)
     rtx target;
     unsigned HOST_WIDE_INT bitsize;
     HOST_WIDE_INT bitpos;
     enum machine_mode mode;
     tree exp, type;
     unsigned int align;
     int cleared;
{
  if (TREE_CODE (exp) == CONSTRUCTOR
      && bitpos % BITS_PER_UNIT == 0
      /* If we have a non-zero bitpos for a register target, then we just
         let store_field do the bitfield handling.  This is unlikely to
         generate unnecessary clear instructions anyways.  */
      && (bitpos == 0 || GET_CODE (target) == MEM))
    {
      if (bitpos != 0)
        target
          = change_address (target,
                            GET_MODE (target) == BLKmode
                            || 0 != (bitpos
                                     % GET_MODE_ALIGNMENT (GET_MODE (target)))
                            ? BLKmode : VOIDmode,
                            plus_constant (XEXP (target, 0),
                                           bitpos / BITS_PER_UNIT));
      store_constructor (exp, target, align, cleared, bitsize / BITS_PER_UNIT);
    }
  else
    store_field (target, bitsize, bitpos, mode, exp, VOIDmode, 0, align,
                 int_size_in_bytes (type), 0);
}

/* Store the value of constructor EXP into the rtx TARGET.
   TARGET is either a REG or a MEM.
   ALIGN is the maximum known alignment for TARGET.
   CLEARED is true if TARGET is known to have been zero'd.
   SIZE is the number of bytes of TARGET we are allowed to modify: this
   may not be the same as the size of EXP if we are assigning to a field
   which has been packed to exclude padding bits.  */

static void
store_constructor (exp, target, align, cleared, size)
     tree exp;
     rtx target;
     unsigned int align;
     int cleared;
     HOST_WIDE_INT size;
{
  tree type = TREE_TYPE (exp);
#ifdef WORD_REGISTER_OPERATIONS
  HOST_WIDE_INT exp_size = int_size_in_bytes (type);
#endif

  /* We know our target cannot conflict, since safe_from_p has been called.  */
#if 0
  /* Don't try copying piece by piece into a hard register
     since that is vulnerable to being clobbered by EXP.
     Instead, construct in a pseudo register and then copy it all.  */
  if (GET_CODE (target) == REG && REGNO (target) < FIRST_PSEUDO_REGISTER)
    {
      rtx temp = gen_reg_rtx (GET_MODE (target));
      store_constructor (exp, temp, align, cleared, size);
      emit_move_insn (target, temp);
      return;
    }
#endif

  if (TREE_CODE (type) == RECORD_TYPE || TREE_CODE (type) == UNION_TYPE
      || TREE_CODE (type) == QUAL_UNION_TYPE)
    {
      register tree elt;

      /* Inform later passes that the whole union value is dead.  */
      if ((TREE_CODE (type) == UNION_TYPE
           || TREE_CODE (type) == QUAL_UNION_TYPE)
          && ! cleared)
        {
          emit_insn (gen_rtx_CLOBBER (VOIDmode, target));

          /* If the constructor is empty, clear the union.  */
          if (! CONSTRUCTOR_ELTS (exp)  && ! cleared)
            clear_storage (target, expr_size (exp), TYPE_ALIGN (type));
        }

      /* If we are building a static constructor into a register,
         set the initial value as zero so we can fold the value into
         a constant.  But if more than one register is involved,
         this probably loses.  */
      else if (GET_CODE (target) == REG && TREE_STATIC (exp)
               && GET_MODE_SIZE (GET_MODE (target)) <= UNITS_PER_WORD)
        {
          if (! cleared)
            emit_move_insn (target, CONST0_RTX (GET_MODE (target)));

          cleared = 1;
        }

      /* If the constructor has fewer fields than the structure
         or if we are initializing the structure to mostly zeros,
         clear the whole structure first.  */
      else if (size > 0
               && ((list_length (CONSTRUCTOR_ELTS (exp))
                    != fields_length (type))
                   || mostly_zeros_p (exp)))
        {
          if (! cleared)
            clear_storage (target, GEN_INT (size), align);

          cleared = 1;
        }
      else if (! cleared)
        /* Inform later passes that the old value is dead.  */
        emit_insn (gen_rtx_CLOBBER (VOIDmode, target));

      /* Store each element of the constructor into
         the corresponding field of TARGET.  */

      for (elt = CONSTRUCTOR_ELTS (exp); elt; elt = TREE_CHAIN (elt))
        {
          register tree field = TREE_PURPOSE (elt);
#ifdef WORD_REGISTER_OPERATIONS
          tree value = TREE_VALUE (elt);
#endif
          register enum machine_mode mode;
          HOST_WIDE_INT bitsize;
          HOST_WIDE_INT bitpos = 0;
          int unsignedp;
          tree offset;
          rtx to_rtx = target;

          /* Just ignore missing fields.
             We cleared the whole structure, above,
             if any fields are missing.  */
          if (field == 0)
            continue;

          if (cleared && is_zeros_p (TREE_VALUE (elt)))
            continue;

          if (host_integerp (DECL_SIZE (field), 1))
            bitsize = tree_low_cst (DECL_SIZE (field), 1);
          else
            bitsize = -1;

          unsignedp = TREE_UNSIGNED (field);
          mode = DECL_MODE (field);
          if (DECL_BIT_FIELD (field))
            mode = VOIDmode;

          offset = DECL_FIELD_OFFSET (field);
          if (host_integerp (offset, 0)
              && host_integerp (bit_position (field), 0))
            {
              bitpos = int_bit_position (field);
              offset = 0;
            }
          else
            bitpos = tree_low_cst (DECL_FIELD_BIT_OFFSET (field), 0);
                              
          if (offset)
            {
              rtx offset_rtx;

              if (contains_placeholder_p (offset))
                offset = build (WITH_RECORD_EXPR, sizetype,
                                offset, make_tree (TREE_TYPE (exp), target));

              offset_rtx = expand_expr (offset, NULL_RTX, VOIDmode, 0);
              if (GET_CODE (to_rtx) != MEM)
                abort ();

              if (GET_MODE (offset_rtx) != ptr_mode)
                {
#ifdef POINTERS_EXTEND_UNSIGNED
                  offset_rtx = convert_memory_address (ptr_mode, offset_rtx);
#else
                  offset_rtx = convert_to_mode (ptr_mode, offset_rtx, 0);
#endif
                }

              to_rtx
                = change_address (to_rtx, VOIDmode,
                                  gen_rtx_PLUS (ptr_mode, XEXP (to_rtx, 0),
                                                force_reg (ptr_mode,
                                                           offset_rtx)));
              align = DECL_OFFSET_ALIGN (field);
            }

          if (TREE_READONLY (field))
            {
              if (GET_CODE (to_rtx) == MEM)
                to_rtx = copy_rtx (to_rtx);

              RTX_UNCHANGING_P (to_rtx) = 1;
            }

#ifdef WORD_REGISTER_OPERATIONS
          /* If this initializes a field that is smaller than a word, at the
             start of a word, try to widen it to a full word.
             This special case allows us to output C++ member function
             initializations in a form that the optimizers can understand.  */
          if (GET_CODE (target) == REG
              && bitsize < BITS_PER_WORD
              && bitpos % BITS_PER_WORD == 0
              && GET_MODE_CLASS (mode) == MODE_INT
              && TREE_CODE (value) == INTEGER_CST
              && exp_size >= 0
              && bitpos + BITS_PER_WORD <= exp_size * BITS_PER_UNIT)
            {
              tree type = TREE_TYPE (value);
              if (TYPE_PRECISION (type) < BITS_PER_WORD)
                {
                  type = type_for_size (BITS_PER_WORD, TREE_UNSIGNED (type));
                  value = convert (type, value);
                }
              if (BYTES_BIG_ENDIAN)
                value
                  = fold (build (LSHIFT_EXPR, type, value,
                                 build_int_2 (BITS_PER_WORD - bitsize, 0)));
              bitsize = BITS_PER_WORD;
              mode = word_mode;
            }
#endif
          store_constructor_field (to_rtx, bitsize, bitpos, mode,
                                   TREE_VALUE (elt), type, align, cleared);
        }
    }
  else if (TREE_CODE (type) == ARRAY_TYPE)
    {
      register tree elt;
      register int i;
      int need_to_clear;
      tree domain = TYPE_DOMAIN (type);
      HOST_WIDE_INT minelt = TREE_INT_CST_LOW (TYPE_MIN_VALUE (domain));
      HOST_WIDE_INT maxelt = TREE_INT_CST_LOW (TYPE_MAX_VALUE (domain));
      tree elttype = TREE_TYPE (type);

      /* If the constructor has fewer elements than the array,
         clear the whole array first.  Similarly if this is
         static constructor of a non-BLKmode object.  */
      if (cleared || (GET_CODE (target) == REG && TREE_STATIC (exp)))
        need_to_clear = 1;
      else
        {
          HOST_WIDE_INT count = 0, zero_count = 0;
          need_to_clear = 0;
          /* This loop is a more accurate version of the loop in
             mostly_zeros_p (it handles RANGE_EXPR in an index).
             It is also needed to check for missing elements.  */
          for (elt = CONSTRUCTOR_ELTS (exp);
               elt != NULL_TREE;
               elt = TREE_CHAIN (elt))
            {
              tree index = TREE_PURPOSE (elt);
              HOST_WIDE_INT this_node_count;

              if (index != NULL_TREE && TREE_CODE (index) == RANGE_EXPR)
                {
                  tree lo_index = TREE_OPERAND (index, 0);
                  tree hi_index = TREE_OPERAND (index, 1);

                  if (! host_integerp (lo_index, 1)
                      || ! host_integerp (hi_index, 1))
                    {
                      need_to_clear = 1;
                      break;
                    }

                  this_node_count = (tree_low_cst (hi_index, 1)
                                     - tree_low_cst (lo_index, 1) + 1);
                }
              else
                this_node_count = 1;
              count += this_node_count;
              if (mostly_zeros_p (TREE_VALUE (elt)))
                zero_count += this_node_count;
            }
          /* Clear the entire array first if there are any missing elements,
             or if the incidence of zero elements is >= 75%.  */
          if (count < maxelt - minelt + 1
              || 4 * zero_count >= 3 * count)
            need_to_clear = 1;
        }
      if (need_to_clear && size > 0)
        {
          if (! cleared)
            clear_storage (target, GEN_INT (size), align);
          cleared = 1;
        }
      else
        /* Inform later passes that the old value is dead.  */
        emit_insn (gen_rtx_CLOBBER (VOIDmode, target));

      /* Store each element of the constructor into
         the corresponding element of TARGET, determined
         by counting the elements.  */
      for (elt = CONSTRUCTOR_ELTS (exp), i = 0;
           elt;
           elt = TREE_CHAIN (elt), i++)
        {
          register enum machine_mode mode;
          HOST_WIDE_INT bitsize;
          HOST_WIDE_INT bitpos;
          int unsignedp;
          tree value = TREE_VALUE (elt);
          unsigned int align = TYPE_ALIGN (TREE_TYPE (value));
          tree index = TREE_PURPOSE (elt);
          rtx xtarget = target;

          if (cleared && is_zeros_p (value))
            continue;

          unsignedp = TREE_UNSIGNED (elttype);
          mode = TYPE_MODE (elttype);
          if (mode == BLKmode)
            bitsize = (host_integerp (TYPE_SIZE (elttype), 1)
                       ? tree_low_cst (TYPE_SIZE (elttype), 1)
                       : -1);
          else
            bitsize = GET_MODE_BITSIZE (mode);

          if (index != NULL_TREE && TREE_CODE (index) == RANGE_EXPR)
            {
              tree lo_index = TREE_OPERAND (index, 0);
              tree hi_index = TREE_OPERAND (index, 1);
              rtx index_r, pos_rtx, addr, hi_r, loop_top, loop_end;
              struct nesting *loop;
              HOST_WIDE_INT lo, hi, count;
              tree position;

              /* If the range is constant and "small", unroll the loop.  */
              if (host_integerp (lo_index, 0)
                  && host_integerp (hi_index, 0)
                  && (lo = tree_low_cst (lo_index, 0),
                      hi = tree_low_cst (hi_index, 0),
                      count = hi - lo + 1,
                      (GET_CODE (target) != MEM
                       || count <= 2
                       || (host_integerp (TYPE_SIZE (elttype), 1)
                           && (tree_low_cst (TYPE_SIZE (elttype), 1) * count
                               <= 40 * 8)))))
                {
                  lo -= minelt;  hi -= minelt;
                  for (; lo <= hi; lo++)
                    {
                      bitpos = lo * tree_low_cst (TYPE_SIZE (elttype), 0);
                      store_constructor_field (target, bitsize, bitpos, mode,
                                               value, type, align, cleared);
                    }
                }
              else
                {
                  hi_r = expand_expr (hi_index, NULL_RTX, VOIDmode, 0);
                  loop_top = gen_label_rtx ();
                  loop_end = gen_label_rtx ();

                  unsignedp = TREE_UNSIGNED (domain);

                  index = build_decl (VAR_DECL, NULL_TREE, domain);

                  DECL_RTL (index) = index_r
                    = gen_reg_rtx (promote_mode (domain, DECL_MODE (index),
                                                 &unsignedp, 0));

                  if (TREE_CODE (value) == SAVE_EXPR
                      && SAVE_EXPR_RTL (value) == 0)
                    {
                      /* Make sure value gets expanded once before the
                         loop.  */
                      expand_expr (value, const0_rtx, VOIDmode, 0);
                      emit_queue ();
                    }
                  store_expr (lo_index, index_r, 0);
                  loop = expand_start_loop (0);

                  /* Assign value to element index.  */
                  position
                    = convert (ssizetype,
                               fold (build (MINUS_EXPR, TREE_TYPE (index),
                                            index, TYPE_MIN_VALUE (domain))));
                  position = size_binop (MULT_EXPR, position,
                                         convert (ssizetype,
                                                  TYPE_SIZE_UNIT (elttype)));

                  pos_rtx = expand_expr (position, 0, VOIDmode, 0);
                  addr = gen_rtx_PLUS (Pmode, XEXP (target, 0), pos_rtx);
                  xtarget = change_address (target, mode, addr);
                  if (TREE_CODE (value) == CONSTRUCTOR)
                    store_constructor (value, xtarget, align, cleared,
                                       bitsize / BITS_PER_UNIT);
                  else
                    store_expr (value, xtarget, 0);

                  expand_exit_loop_if_false (loop,
                                             build (LT_EXPR, integer_type_node,
                                                    index, hi_index));

                  expand_increment (build (PREINCREMENT_EXPR,
                                           TREE_TYPE (index),
                                           index, integer_one_node), 0, 0);
                  expand_end_loop ();
                  emit_label (loop_end);
                }
            }
          else if ((index != 0 && ! host_integerp (index, 0))
                   || ! host_integerp (TYPE_SIZE (elttype), 1))
            {
              rtx pos_rtx, addr;
              tree position;

              if (index == 0)
                index = ssize_int (1);

              if (minelt)
                index = convert (ssizetype,
                                 fold (build (MINUS_EXPR, index,
                                              TYPE_MIN_VALUE (domain))));

              position = size_binop (MULT_EXPR, index,
                                     convert (ssizetype,
                                              TYPE_SIZE_UNIT (elttype)));
              pos_rtx = expand_expr (position, 0, VOIDmode, 0);
              addr = gen_rtx_PLUS (Pmode, XEXP (target, 0), pos_rtx);
              xtarget = change_address (target, mode, addr);
              store_expr (value, xtarget, 0);
            }
          else
            {
              if (index != 0)
                bitpos = ((tree_low_cst (index, 0) - minelt)
                          * tree_low_cst (TYPE_SIZE (elttype), 1));
              else
                bitpos = (i * tree_low_cst (TYPE_SIZE (elttype), 1));

              store_constructor_field (target, bitsize, bitpos, mode, value,
                                       type, align, cleared);
            }
        }
    }

  /* Set constructor assignments */
  else if (TREE_CODE (type) == SET_TYPE)
    {
      tree elt = CONSTRUCTOR_ELTS (exp);
      unsigned HOST_WIDE_INT nbytes = int_size_in_bytes (type), nbits;
      tree domain = TYPE_DOMAIN (type);
      tree domain_min, domain_max, bitlength;

      /* The default implementation strategy is to extract the constant
         parts of the constructor, use that to initialize the target,
         and then "or" in whatever non-constant ranges we need in addition.

         If a large set is all zero or all ones, it is
         probably better to set it using memset (if available) or bzero.
         Also, if a large set has just a single range, it may also be
         better to first clear all the first clear the set (using
         bzero/memset), and set the bits we want.  */
       
      /* Check for all zeros.  */
      if (elt == NULL_TREE && size > 0)
        {
          if (!cleared)
            clear_storage (target, GEN_INT (size), TYPE_ALIGN (type));
          return;
        }

      domain_min = convert (sizetype, TYPE_MIN_VALUE (domain));
      domain_max = convert (sizetype, TYPE_MAX_VALUE (domain));
      bitlength = size_binop (PLUS_EXPR,
                              size_diffop (domain_max, domain_min),
                              ssize_int (1));

      nbits = tree_low_cst (bitlength, 1);

      /* For "small" sets, or "medium-sized" (up to 32 bytes) sets that
         are "complicated" (more than one range), initialize (the
         constant parts) by copying from a constant.  */         
      if (GET_MODE (target) != BLKmode || nbits <= 2 * BITS_PER_WORD
          || (nbytes <= 32 && TREE_CHAIN (elt) != NULL_TREE))
        {
          unsigned int set_word_size = TYPE_ALIGN (TREE_TYPE (exp));
          enum machine_mode mode = mode_for_size (set_word_size, MODE_INT, 1);
          char *bit_buffer = (char *) alloca (nbits);
          HOST_WIDE_INT word = 0;
          unsigned int bit_pos = 0;
          unsigned int ibit = 0;
          unsigned int offset = 0;  /* In bytes from beginning of set.  */

          elt = get_set_constructor_bits (exp, bit_buffer, nbits);
          for (;;)
            {
              if (bit_buffer[ibit])
                {
                  if (BYTES_BIG_ENDIAN)
                    word |= (1 << (set_word_size - 1 - bit_pos));
                  else
                    word |= 1 << bit_pos;
                }

              bit_pos++;  ibit++;
              if (bit_pos >= set_word_size || ibit == nbits)
                {
                  if (word != 0 || ! cleared)
                    {
                      rtx datum = GEN_INT (word);
                      rtx to_rtx;

                      /* The assumption here is that it is safe to use
                         XEXP if the set is multi-word, but not if
                         it's single-word.  */
                      if (GET_CODE (target) == MEM)
                        {
                          to_rtx = plus_constant (XEXP (target, 0), offset);
                          to_rtx = change_address (target, mode, to_rtx);
                        }
                      else if (offset == 0) 
                        to_rtx = target;
                      else
                        abort ();
                      emit_move_insn (to_rtx, datum);
                    }

                  if (ibit == nbits)
                    break;
                  word = 0;
                  bit_pos = 0;
                  offset += set_word_size / BITS_PER_UNIT;
                }
            }
        }
      else if (!cleared)
        /* Don't bother clearing storage if the set is all ones.  */
        if (TREE_CHAIN (elt) != NULL_TREE
            || (TREE_PURPOSE (elt) == NULL_TREE
                ? nbits != 1
                : ( ! host_integerp (TREE_VALUE (elt), 0)
                   || ! host_integerp (TREE_PURPOSE (elt), 0)
                   || (tree_low_cst (TREE_VALUE (elt), 0)
                       - tree_low_cst (TREE_PURPOSE (elt), 0) + 1
                       != (HOST_WIDE_INT) nbits))))
          clear_storage (target, expr_size (exp), TYPE_ALIGN (type));
          
      for (; elt != NULL_TREE; elt = TREE_CHAIN (elt))
        {
          /* start of range of element or NULL */
          tree startbit = TREE_PURPOSE (elt);
          /* end of range of element, or element value */
          tree endbit   = TREE_VALUE (elt);
#ifdef TARGET_MEM_FUNCTIONS
          HOST_WIDE_INT startb, endb;
#endif
          rtx bitlength_rtx, startbit_rtx, endbit_rtx, targetx;

          bitlength_rtx = expand_expr (bitlength,
                                       NULL_RTX, MEM, EXPAND_CONST_ADDRESS);

          /* handle non-range tuple element like [ expr ]  */
          if (startbit == NULL_TREE)
            {
              startbit = save_expr (endbit);
              endbit = startbit;
            }

          startbit = convert (sizetype, startbit);
          endbit = convert (sizetype, endbit);
          if (! integer_zerop (domain_min))
            {
              startbit = size_binop (MINUS_EXPR, startbit, domain_min);
              endbit = size_binop (MINUS_EXPR, endbit, domain_min);
            }
          startbit_rtx = expand_expr (startbit, NULL_RTX, MEM, 
                                      EXPAND_CONST_ADDRESS);
          endbit_rtx = expand_expr (endbit, NULL_RTX, MEM, 
                                    EXPAND_CONST_ADDRESS);

          if (REG_P (target))
            {
              targetx = assign_stack_temp (GET_MODE (target),
                                           GET_MODE_SIZE (GET_MODE (target)),
                                           0);
              emit_move_insn (targetx, target);
            }

          else if (GET_CODE (target) == MEM)
            targetx = target;
          else
            abort ();

#ifdef TARGET_MEM_FUNCTIONS
          /* Optimization:  If startbit and endbit are
             constants divisible by BITS_PER_UNIT,
             call memset instead.  */
          if (TREE_CODE (startbit) == INTEGER_CST
              && TREE_CODE (endbit) == INTEGER_CST
              && (startb = TREE_INT_CST_LOW (startbit)) % BITS_PER_UNIT == 0
              && (endb = TREE_INT_CST_LOW (endbit) + 1) % BITS_PER_UNIT == 0)
            {
              emit_library_call (memset_libfunc, 0,
                                 VOIDmode, 3,
                                 plus_constant (XEXP (targetx, 0),
                                                startb / BITS_PER_UNIT),
                                 Pmode,
                                 constm1_rtx, TYPE_MODE (integer_type_node),
                                 GEN_INT ((endb - startb) / BITS_PER_UNIT),
                                 TYPE_MODE (sizetype));
            }
          else
#endif
            emit_library_call (gen_rtx_SYMBOL_REF (Pmode, "__setbits"),
                               0, VOIDmode, 4, XEXP (targetx, 0), Pmode,
                               bitlength_rtx, TYPE_MODE (sizetype),
                               startbit_rtx, TYPE_MODE (sizetype),
                               endbit_rtx, TYPE_MODE (sizetype));

          if (REG_P (target))
            emit_move_insn (target, targetx);
        }
    }

  else
    abort ();
}

/* Store the value of EXP (an expression tree)
   into a subfield of TARGET which has mode MODE and occupies
   BITSIZE bits, starting BITPOS bits from the start of TARGET.
   If MODE is VOIDmode, it means that we are storing into a bit-field.

   If VALUE_MODE is VOIDmode, return nothing in particular.
   UNSIGNEDP is not used in this case.

   Otherwise, return an rtx for the value stored.  This rtx
   has mode VALUE_MODE if that is convenient to do.
   In this case, UNSIGNEDP must be nonzero if the value is an unsigned type.

   ALIGN is the alignment that TARGET is known to have.
   TOTAL_SIZE is the size in bytes of the structure, or -1 if varying.  

   ALIAS_SET is the alias set for the destination.  This value will
   (in general) be different from that for TARGET, since TARGET is a
   reference to the containing structure.  */

static rtx
store_field (target, bitsize, bitpos, mode, exp, value_mode,
             unsignedp, align, total_size, alias_set)
     rtx target;
     HOST_WIDE_INT bitsize;
     HOST_WIDE_INT bitpos;
     enum machine_mode mode;
     tree exp;
     enum machine_mode value_mode;
     int unsignedp;
     unsigned int align;
     HOST_WIDE_INT total_size;
     int alias_set;
{
  HOST_WIDE_INT width_mask = 0;

  if (TREE_CODE (exp) == ERROR_MARK)
    return const0_rtx;

  if (bitsize < HOST_BITS_PER_WIDE_INT)
    width_mask = ((HOST_WIDE_INT) 1 << bitsize) - 1;

  /* If we are storing into an unaligned field of an aligned union that is
     in a register, we may have the mode of TARGET being an integer mode but
     MODE == BLKmode.  In that case, get an aligned object whose size and
     alignment are the same as TARGET and store TARGET into it (we can avoid
     the store if the field being stored is the entire width of TARGET).  Then
     call ourselves recursively to store the field into a BLKmode version of
     that object.  Finally, load from the object into TARGET.  This is not
     very efficient in general, but should only be slightly more expensive
     than the otherwise-required unaligned accesses.  Perhaps this can be
     cleaned up later.  */

  if (mode == BLKmode
      && (GET_CODE (target) == REG || GET_CODE (target) == SUBREG))
    {
      rtx object = assign_stack_temp (GET_MODE (target),
                                      GET_MODE_SIZE (GET_MODE (target)), 0);
      rtx blk_object = copy_rtx (object);

      MEM_SET_IN_STRUCT_P (object, 1);
      MEM_SET_IN_STRUCT_P (blk_object, 1);
      PUT_MODE (blk_object, BLKmode);

      if (bitsize != GET_MODE_BITSIZE (GET_MODE (target)))
        emit_move_insn (object, target);

      store_field (blk_object, bitsize, bitpos, mode, exp, VOIDmode, 0,
                   align, total_size, alias_set);

      /* Even though we aren't returning target, we need to
         give it the updated value.  */
      emit_move_insn (target, object);

      return blk_object;
    }

  if (GET_CODE (target) == CONCAT)
    {
      /* We're storing into a struct containing a single __complex.  */

      if (bitpos != 0)
        abort ();
      return store_expr (exp, target, 0);
    }

  /* If the structure is in a register or if the component
     is a bit field, we cannot use addressing to access it.
     Use bit-field techniques or SUBREG to store in it.  */

  if (mode == VOIDmode
      || (mode != BLKmode && ! direct_store[(int) mode]
          && GET_MODE_CLASS (mode) != MODE_COMPLEX_INT
          && GET_MODE_CLASS (mode) != MODE_COMPLEX_FLOAT)
      || GET_CODE (target) == REG
      || GET_CODE (target) == SUBREG
      /* If the field isn't aligned enough to store as an ordinary memref,
         store it as a bit field.  */
      || (mode != BLKmode && SLOW_UNALIGNED_ACCESS (mode, align)
          && (align < GET_MODE_ALIGNMENT (mode)
              || bitpos % GET_MODE_ALIGNMENT (mode)))
      || (mode == BLKmode && SLOW_UNALIGNED_ACCESS (mode, align)
          && (TYPE_ALIGN (TREE_TYPE (exp)) > align
              || bitpos % TYPE_ALIGN (TREE_TYPE (exp)) != 0))
      /* If the RHS and field are a constant size and the size of the
         RHS isn't the same size as the bitfield, we must use bitfield
         operations.  */
      || (bitsize >= 0
          && TREE_CODE (TYPE_SIZE (TREE_TYPE (exp))) == INTEGER_CST
          && compare_tree_int (TYPE_SIZE (TREE_TYPE (exp)), bitsize) != 0))
    {
      rtx temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);

      /* If BITSIZE is narrower than the size of the type of EXP
         we will be narrowing TEMP.  Normally, what's wanted are the
         low-order bits.  However, if EXP's type is a record and this is
         big-endian machine, we want the upper BITSIZE bits.  */
      if (BYTES_BIG_ENDIAN && GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT
          && bitsize < GET_MODE_BITSIZE (GET_MODE (temp))
          && TREE_CODE (TREE_TYPE (exp)) == RECORD_TYPE)
        temp = expand_shift (RSHIFT_EXPR, GET_MODE (temp), temp,
                             size_int (GET_MODE_BITSIZE (GET_MODE (temp))
                                       - bitsize),
                             temp, 1);

      /* Unless MODE is VOIDmode or BLKmode, convert TEMP to
         MODE.  */
      if (mode != VOIDmode && mode != BLKmode
          && mode != TYPE_MODE (TREE_TYPE (exp)))
        temp = convert_modes (mode, TYPE_MODE (TREE_TYPE (exp)), temp, 1);

      /* If the modes of TARGET and TEMP are both BLKmode, both
         must be in memory and BITPOS must be aligned on a byte
         boundary.  If so, we simply do a block copy.  */
      if (GET_MODE (target) == BLKmode && GET_MODE (temp) == BLKmode)
        {
          unsigned int exp_align = expr_align (exp);

          if (GET_CODE (target) != MEM || GET_CODE (temp) != MEM
              || bitpos % BITS_PER_UNIT != 0)
            abort ();

          target = change_address (target, VOIDmode,
                                   plus_constant (XEXP (target, 0),
                                                bitpos / BITS_PER_UNIT));

          /* Make sure that ALIGN is no stricter than the alignment of EXP.  */
          align = MIN (exp_align, align);

          /* Find an alignment that is consistent with the bit position.  */
          while ((bitpos % align) != 0)
            align >>= 1;

          emit_block_move (target, temp,
                           GEN_INT ((bitsize + BITS_PER_UNIT - 1)
                                    / BITS_PER_UNIT),
                           align);

          return value_mode == VOIDmode ? const0_rtx : target;
        }

      /* Store the value in the bitfield.  */
      store_bit_field (target, bitsize, bitpos, mode, temp, align, total_size);
      if (value_mode != VOIDmode)
        {
          /* The caller wants an rtx for the value.  */
          /* If possible, avoid refetching from the bitfield itself.  */
          if (width_mask != 0
              && ! (GET_CODE (target) == MEM && MEM_VOLATILE_P (target)))
            {
              tree count;
              enum machine_mode tmode;

              if (unsignedp)
                return expand_and (temp, GEN_INT (width_mask), NULL_RTX);
              tmode = GET_MODE (temp);
              if (tmode == VOIDmode)
                tmode = value_mode;
              count = build_int_2 (GET_MODE_BITSIZE (tmode) - bitsize, 0);
              temp = expand_shift (LSHIFT_EXPR, tmode, temp, count, 0, 0);
              return expand_shift (RSHIFT_EXPR, tmode, temp, count, 0, 0);
            }
          return extract_bit_field (target, bitsize, bitpos, unsignedp,
                                    NULL_RTX, value_mode, 0, align,
                                    total_size);
        }
      return const0_rtx;
    }
  else
    {
      rtx addr = XEXP (target, 0);
      rtx to_rtx;

      /* If a value is wanted, it must be the lhs;
         so make the address stable for multiple use.  */

      if (value_mode != VOIDmode && GET_CODE (addr) != REG
          && ! CONSTANT_ADDRESS_P (addr)
          /* A frame-pointer reference is already stable.  */
          && ! (GET_CODE (addr) == PLUS
                && GET_CODE (XEXP (addr, 1)) == CONST_INT
                && (XEXP (addr, 0) == virtual_incoming_args_rtx
                    || XEXP (addr, 0) == virtual_stack_vars_rtx)))
        addr = copy_to_reg (addr);

      /* Now build a reference to just the desired component.  */

      to_rtx = copy_rtx (change_address (target, mode,
                                         plus_constant (addr,
                                                        (bitpos
                                                         / BITS_PER_UNIT))));
      MEM_SET_IN_STRUCT_P (to_rtx, 1);
      MEM_ALIAS_SET (to_rtx) = alias_set;

      return store_expr (exp, to_rtx, value_mode != VOIDmode);
    }
}
\f
/* Given an expression EXP that may be a COMPONENT_REF, a BIT_FIELD_REF,
   or an ARRAY_REF, look for nested COMPONENT_REFs, BIT_FIELD_REFs, or
   ARRAY_REFs and find the ultimate containing object, which we return.

   We set *PBITSIZE to the size in bits that we want, *PBITPOS to the
   bit position, and *PUNSIGNEDP to the signedness of the field.
   If the position of the field is variable, we store a tree
   giving the variable offset (in units) in *POFFSET.
   This offset is in addition to the bit position.
   If the position is not variable, we store 0 in *POFFSET.
   We set *PALIGNMENT to the alignment of the address that will be
   computed.  This is the alignment of the thing we return if *POFFSET
   is zero, but can be more less strictly aligned if *POFFSET is nonzero.

   If any of the extraction expressions is volatile,
   we store 1 in *PVOLATILEP.  Otherwise we don't change that.

   If the field is a bit-field, *PMODE is set to VOIDmode.  Otherwise, it
   is a mode that can be used to access the field.  In that case, *PBITSIZE
   is redundant.

   If the field describes a variable-sized object, *PMODE is set to
   VOIDmode and *PBITSIZE is set to -1.  An access cannot be made in
   this case, but the address of the object can be found.   */

tree
get_inner_reference (exp, pbitsize, pbitpos, poffset, pmode,
                     punsignedp, pvolatilep, palignment)
     tree exp;
     HOST_WIDE_INT *pbitsize;
     HOST_WIDE_INT *pbitpos;
     tree *poffset;
     enum machine_mode *pmode;
     int *punsignedp;
     int *pvolatilep;
     unsigned int *palignment;
{
  tree size_tree = 0;
  enum machine_mode mode = VOIDmode;
  tree offset = size_zero_node;
  tree bit_offset = bitsize_zero_node;
  unsigned int alignment = BIGGEST_ALIGNMENT;
  tree tem;

  /* First get the mode, signedness, and size.  We do this from just the
     outermost expression.  */
  if (TREE_CODE (exp) == COMPONENT_REF)
    {
      size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
      if (! DECL_BIT_FIELD (TREE_OPERAND (exp, 1)))
        mode = DECL_MODE (TREE_OPERAND (exp, 1));

      *punsignedp = TREE_UNSIGNED (TREE_OPERAND (exp, 1));
    }
  else if (TREE_CODE (exp) == BIT_FIELD_REF)
    {
      size_tree = TREE_OPERAND (exp, 1);
      *punsignedp = TREE_UNSIGNED (exp);
    }
  else
    {
      mode = TYPE_MODE (TREE_TYPE (exp));
      *punsignedp = TREE_UNSIGNED (TREE_TYPE (exp));

      if (mode == BLKmode)
        size_tree = TYPE_SIZE (TREE_TYPE (exp));
      else
        *pbitsize = GET_MODE_BITSIZE (mode);
    }
      
  if (size_tree != 0)
    {
      if (! host_integerp (size_tree, 1))
        mode = BLKmode, *pbitsize = -1;
      else
        *pbitsize = tree_low_cst (size_tree, 1);
    }

  /* Compute cumulative bit-offset for nested component-refs and array-refs,
     and find the ultimate containing object.  */
  while (1)
    {
      if (TREE_CODE (exp) == BIT_FIELD_REF)
        bit_offset = size_binop (PLUS_EXPR, bit_offset, TREE_OPERAND (exp, 2));
      else if (TREE_CODE (exp) == COMPONENT_REF)
        {
          tree field = TREE_OPERAND (exp, 1);
          tree this_offset = DECL_FIELD_OFFSET (field);

          /* If this field hasn't been filled in yet, don't go
             past it.  This should only happen when folding expressions
             made during type construction.  */
          if (this_offset == 0)
            break;
          else if (! TREE_CONSTANT (this_offset)
                   && contains_placeholder_p (this_offset))
            this_offset = build (WITH_RECORD_EXPR, sizetype, this_offset, exp);

          offset = size_binop (PLUS_EXPR, offset, this_offset);
          bit_offset = size_binop (PLUS_EXPR, bit_offset,
                                   DECL_FIELD_BIT_OFFSET (field));

          if (! host_integerp (offset, 0))
            alignment = MIN (alignment, DECL_OFFSET_ALIGN (field));
        }

      else if (TREE_CODE (exp) == ARRAY_REF)
        {
          tree index = TREE_OPERAND (exp, 1);
          tree domain = TYPE_DOMAIN (TREE_TYPE (TREE_OPERAND (exp, 0)));
          tree low_bound = (domain ? TYPE_MIN_VALUE (domain) : 0);
          tree unit_size = TYPE_SIZE_UNIT (TREE_TYPE (exp));

          /* We assume all arrays have sizes that are a multiple of a byte.
             First subtract the lower bound, if any, in the type of the
             index, then convert to sizetype and multiply by the size of the
             array element.  */
          if (low_bound != 0 && ! integer_zerop (low_bound))
            index = fold (build (MINUS_EXPR, TREE_TYPE (index),
                                 index, low_bound));

          /* If the index has a self-referential type, pass it to a
             WITH_RECORD_EXPR; if the component size is, pass our
             component to one.  */
          if (! TREE_CONSTANT (index)
              && contains_placeholder_p (index))
            index = build (WITH_RECORD_EXPR, TREE_TYPE (index), index, exp);
          if (! TREE_CONSTANT (unit_size)
              && contains_placeholder_p (unit_size))
            unit_size = build (WITH_RECORD_EXPR, sizetype, unit_size,
                               TREE_OPERAND (exp, 0));

          offset = size_binop (PLUS_EXPR, offset,
                               size_binop (MULT_EXPR,
                                           convert (sizetype, index),
                                           unit_size));
        }

      else if (TREE_CODE (exp) != NON_LVALUE_EXPR
               && ! ((TREE_CODE (exp) == NOP_EXPR
                      || TREE_CODE (exp) == CONVERT_EXPR)
                     && (TYPE_MODE (TREE_TYPE (exp))
                         == TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))))))
        break;

      /* If any reference in the chain is volatile, the effect is volatile.  */
      if (TREE_THIS_VOLATILE (exp))
        *pvolatilep = 1;

      /* If the offset is non-constant already, then we can't assume any
         alignment more than the alignment here.  */
      if (! TREE_CONSTANT (offset))
        alignment = MIN (alignment, TYPE_ALIGN (TREE_TYPE (exp)));

      exp = TREE_OPERAND (exp, 0);
    }

  if (DECL_P (exp))
    alignment = MIN (alignment, DECL_ALIGN (exp));
  else if (TREE_TYPE (exp) != 0)
    alignment = MIN (alignment, TYPE_ALIGN (TREE_TYPE (exp)));

  /* If OFFSET is constant, see if we can return the whole thing as a
     constant bit position.  Otherwise, split it up.  */
  if (host_integerp (offset, 0)
      && 0 != (tem = size_binop (MULT_EXPR, convert (bitsizetype, offset),
                                 bitsize_unit_node))
      && 0 != (tem = size_binop (PLUS_EXPR, tem, bit_offset))
      && host_integerp (tem, 0))
    *pbitpos = tree_low_cst (tem, 0), *poffset = 0;
  else
    *pbitpos = tree_low_cst (bit_offset, 0), *poffset = offset;

  *pmode = mode;
  *palignment = alignment;
  return exp;
}

/* Subroutine of expand_exp: compute memory_usage from modifier.  */

static enum memory_use_mode
get_memory_usage_from_modifier (modifier)
     enum expand_modifier modifier;
{
  switch (modifier)
    {
    case EXPAND_NORMAL:
    case EXPAND_SUM:
      return MEMORY_USE_RO;
      break;
    case EXPAND_MEMORY_USE_WO:
      return MEMORY_USE_WO;
      break;
    case EXPAND_MEMORY_USE_RW:
      return MEMORY_USE_RW;
      break;
    case EXPAND_MEMORY_USE_DONT:
      /* EXPAND_CONST_ADDRESS and EXPAND_INITIALIZER are converted into
         MEMORY_USE_DONT, because they are modifiers to a call of
         expand_expr in the ADDR_EXPR case of expand_expr.  */
    case EXPAND_CONST_ADDRESS:
    case EXPAND_INITIALIZER:
      return MEMORY_USE_DONT;
    case EXPAND_MEMORY_USE_BAD:
    default:
      abort ();
    }
}
\f
/* Given an rtx VALUE that may contain additions and multiplications,
   return an equivalent value that just refers to a register or memory.
   This is done by generating instructions to perform the arithmetic
   and returning a pseudo-register containing the value.

   The returned value may be a REG, SUBREG, MEM or constant.  */

rtx
force_operand (value, target)
     rtx value, target;
{
  register optab binoptab = 0;
  /* Use a temporary to force order of execution of calls to
     `force_operand'.  */
  rtx tmp;
  register rtx op2;
  /* Use subtarget as the target for operand 0 of a binary operation.  */
  register rtx subtarget = get_subtarget (target);

  /* Check for a PIC address load.  */
  if (flag_pic
      && (GET_CODE (value) == PLUS || GET_CODE (value) == MINUS)
      && XEXP (value, 0) == pic_offset_table_rtx
      && (GET_CODE (XEXP (value, 1)) == SYMBOL_REF
          || GET_CODE (XEXP (value, 1)) == LABEL_REF
          || GET_CODE (XEXP (value, 1)) == CONST))
    {
      if (!subtarget)
        subtarget = gen_reg_rtx (GET_MODE (value));
      emit_move_insn (subtarget, value);
      return subtarget;
    }

  if (GET_CODE (value) == PLUS)
    binoptab = add_optab;
  else if (GET_CODE (value) == MINUS)
    binoptab = sub_optab;
  else if (GET_CODE (value) == MULT)
    {
      op2 = XEXP (value, 1);
      if (!CONSTANT_P (op2)
          && !(GET_CODE (op2) == REG && op2 != subtarget))
        subtarget = 0;
      tmp = force_operand (XEXP (value, 0), subtarget);
      return expand_mult (GET_MODE (value), tmp,
                          force_operand (op2, NULL_RTX),
                          target, 0);
    }

  if (binoptab)
    {
      op2 = XEXP (value, 1);
      if (!CONSTANT_P (op2)
          && !(GET_CODE (op2) == REG && op2 != subtarget))
        subtarget = 0;
      if (binoptab == sub_optab && GET_CODE (op2) == CONST_INT)
        {
          binoptab = add_optab;
          op2 = negate_rtx (GET_MODE (value), op2);
        }

      /* Check for an addition with OP2 a constant integer and our first
         operand a PLUS of a virtual register and something else.  In that
         case, we want to emit the sum of the virtual register and the
         constant first and then add the other value.  This allows virtual
         register instantiation to simply modify the constant rather than
         creating another one around this addition.  */
      if (binoptab == add_optab && GET_CODE (op2) == CONST_INT
          && GET_CODE (XEXP (value, 0)) == PLUS
          && GET_CODE (XEXP (XEXP (value, 0), 0)) == REG
          && REGNO (XEXP (XEXP (value, 0), 0)) >= FIRST_VIRTUAL_REGISTER
          && REGNO (XEXP (XEXP (value, 0), 0)) <= LAST_VIRTUAL_REGISTER)
        {
          rtx temp = expand_binop (GET_MODE (value), binoptab,
                                   XEXP (XEXP (value, 0), 0), op2,
                                   subtarget, 0, OPTAB_LIB_WIDEN);
          return expand_binop (GET_MODE (value), binoptab, temp,
                               force_operand (XEXP (XEXP (value, 0), 1), 0),
                               target, 0, OPTAB_LIB_WIDEN);
        }
                                   
      tmp = force_operand (XEXP (value, 0), subtarget);
      return expand_binop (GET_MODE (value), binoptab, tmp,
                           force_operand (op2, NULL_RTX),
                           target, 0, OPTAB_LIB_WIDEN);
      /* We give UNSIGNEDP = 0 to expand_binop
         because the only operations we are expanding here are signed ones.  */
    }
  return value;
}
\f
/* Subroutine of expand_expr:
   save the non-copied parts (LIST) of an expr (LHS), and return a list
   which can restore these values to their previous values,
   should something modify their storage.  */

static tree
save_noncopied_parts (lhs, list)
     tree lhs;
     tree list;
{
  tree tail;
  tree parts = 0;

  for (tail = list; tail; tail = TREE_CHAIN (tail))
    if (TREE_CODE (TREE_VALUE (tail)) == TREE_LIST)
      parts = chainon (parts, save_noncopied_parts (lhs, TREE_VALUE (tail)));
    else
      {
        tree part = TREE_VALUE (tail);
        tree part_type = TREE_TYPE (part);
        tree to_be_saved = build (COMPONENT_REF, part_type, lhs, part);
        rtx target = assign_temp (part_type, 0, 1, 1);
        if (! memory_address_p (TYPE_MODE (part_type), XEXP (target, 0)))
          target = change_address (target, TYPE_MODE (part_type), NULL_RTX);
        parts = tree_cons (to_be_saved,
                           build (RTL_EXPR, part_type, NULL_TREE,
                                  (tree) target),
                           parts);
        store_expr (TREE_PURPOSE (parts), RTL_EXPR_RTL (TREE_VALUE (parts)), 0);
      }
  return parts;
}

/* Subroutine of expand_expr:
   record the non-copied parts (LIST) of an expr (LHS), and return a list
   which specifies the initial values of these parts.  */

static tree
init_noncopied_parts (lhs, list)
     tree lhs;
     tree list;
{
  tree tail;
  tree parts = 0;

  for (tail = list; tail; tail = TREE_CHAIN (tail))
    if (TREE_CODE (TREE_VALUE (tail)) == TREE_LIST)
      parts = chainon (parts, init_noncopied_parts (lhs, TREE_VALUE (tail)));
    else if (TREE_PURPOSE (tail))
      {
        tree part = TREE_VALUE (tail);
        tree part_type = TREE_TYPE (part);
        tree to_be_initialized = build (COMPONENT_REF, part_type, lhs, part);
        parts = tree_cons (TREE_PURPOSE (tail), to_be_initialized, parts);
      }
  return parts;
}

/* Subroutine of expand_expr: return nonzero iff there is no way that
   EXP can reference X, which is being modified.  TOP_P is nonzero if this
   call is going to be used to determine whether we need a temporary
   for EXP, as opposed to a recursive call to this function.

   It is always safe for this routine to return zero since it merely
   searches for optimization opportunities.  */

static int
safe_from_p (x, exp, top_p)
     rtx x;
     tree exp;
     int top_p;
{
  rtx exp_rtl = 0;
  int i, nops;
  static int save_expr_count;
  static int save_expr_size = 0;
  static tree *save_expr_rewritten;
  static tree save_expr_trees[256];

  if (x == 0
      /* If EXP has varying size, we MUST use a target since we currently
         have no way of allocating temporaries of variable size
         (except for arrays that have TYPE_ARRAY_MAX_SIZE set).
         So we assume here that something at a higher level has prevented a
         clash.  This is somewhat bogus, but the best we can do.  Only
         do this when X is BLKmode and when we are at the top level.  */
      || (top_p && TREE_TYPE (exp) != 0 && COMPLETE_TYPE_P (TREE_TYPE (exp))
          && TREE_CODE (TYPE_SIZE (TREE_TYPE (exp))) != INTEGER_CST
          && (TREE_CODE (TREE_TYPE (exp)) != ARRAY_TYPE
              || TYPE_ARRAY_MAX_SIZE (TREE_TYPE (exp)) == NULL_TREE
              || TREE_CODE (TYPE_ARRAY_MAX_SIZE (TREE_TYPE (exp)))
              != INTEGER_CST)
          && GET_MODE (x) == BLKmode))
    return 1;

  if (top_p && save_expr_size == 0)
    {
      int rtn;

      save_expr_count = 0;
      save_expr_size = sizeof (save_expr_trees) / sizeof (save_expr_trees[0]);
      save_expr_rewritten = &save_expr_trees[0];

      rtn = safe_from_p (x, exp, 1);

      for (i = 0; i < save_expr_count; ++i)
        {
          if (TREE_CODE (save_expr_trees[i]) != ERROR_MARK)
            abort ();
          TREE_SET_CODE (save_expr_trees[i], SAVE_EXPR);
        }

      save_expr_size = 0;

      return rtn;
    }

  /* If this is a subreg of a hard register, declare it unsafe, otherwise,
     find the underlying pseudo.  */
  if (GET_CODE (x) == SUBREG)
    {
      x = SUBREG_REG (x);
      if (GET_CODE (x) == REG && REGNO (x) < FIRST_PSEUDO_REGISTER)
        return 0;
    }

  /* If X is a location in the outgoing argument area, it is always safe.  */
  if (GET_CODE (x) == MEM
      && (XEXP (x, 0) == virtual_outgoing_args_rtx
          || (GET_CODE (XEXP (x, 0)) == PLUS
              && XEXP (XEXP (x, 0), 0) == virtual_outgoing_args_rtx)))
    return 1;

  switch (TREE_CODE_CLASS (TREE_CODE (exp)))
    {
    case 'd':
      exp_rtl = DECL_RTL (exp);
      break;

    case 'c':
      return 1;

    case 'x':
      if (TREE_CODE (exp) == TREE_LIST)
        return ((TREE_VALUE (exp) == 0
                 || safe_from_p (x, TREE_VALUE (exp), 0))
                && (TREE_CHAIN (exp) == 0
                    || safe_from_p (x, TREE_CHAIN (exp), 0)));
      else if (TREE_CODE (exp) == ERROR_MARK)
        return 1;       /* An already-visited SAVE_EXPR? */
      else
        return 0;

    case '1':
      return safe_from_p (x, TREE_OPERAND (exp, 0), 0);

    case '2':
    case '<':
      return (safe_from_p (x, TREE_OPERAND (exp, 0), 0)
              && safe_from_p (x, TREE_OPERAND (exp, 1), 0));

    case 'e':
    case 'r':
      /* Now do code-specific tests.  EXP_RTL is set to any rtx we find in
         the expression.  If it is set, we conflict iff we are that rtx or
         both are in memory.  Otherwise, we check all operands of the
         expression recursively.  */

      switch (TREE_CODE (exp))
        {
        case ADDR_EXPR:
          return (staticp (TREE_OPERAND (exp, 0))
                  || safe_from_p (x, TREE_OPERAND (exp, 0), 0)
                  || TREE_STATIC (exp));

        case INDIRECT_REF:
          if (GET_CODE (x) == MEM)
            return 0;
          break;

        case CALL_EXPR:
          exp_rtl = CALL_EXPR_RTL (exp);
          if (exp_rtl == 0)
            {
              /* Assume that the call will clobber all hard registers and
                 all of memory.  */
              if ((GET_CODE (x) == REG && REGNO (x) < FIRST_PSEUDO_REGISTER)
                  || GET_CODE (x) == MEM)
                return 0;
            }

          break;

        case RTL_EXPR:
          /* If a sequence exists, we would have to scan every instruction
             in the sequence to see if it was safe.  This is probably not
             worthwhile.  */
          if (RTL_EXPR_SEQUENCE (exp))
            return 0;

          exp_rtl = RTL_EXPR_RTL (exp);
          break;

        case WITH_CLEANUP_EXPR:
          exp_rtl = RTL_EXPR_RTL (exp);
          break;

        case CLEANUP_POINT_EXPR:
          return safe_from_p (x, TREE_OPERAND (exp, 0), 0);

        case SAVE_EXPR:
          exp_rtl = SAVE_EXPR_RTL (exp);
          if (exp_rtl)
            break;

          /* This SAVE_EXPR might appear many times in the top-level
             safe_from_p() expression, and if it has a complex
             subexpression, examining it multiple times could result
             in a combinatorial explosion.  E.g. on an Alpha
             running at least 200MHz, a Fortran test case compiled with
             optimization took about 28 minutes to compile -- even though
             it was only a few lines long, and the complicated line causing
             so much time to be spent in the earlier version of safe_from_p()
             had only 293 or so unique nodes.

             So, turn this SAVE_EXPR into an ERROR_MARK for now, but remember
             where it is so we can turn it back in the top-level safe_from_p()
             when we're done.  */

          /* For now, don't bother re-sizing the array. */
          if (save_expr_count >= save_expr_size)
            return 0;
          save_expr_rewritten[save_expr_count++] = exp;

          nops = TREE_CODE_LENGTH (SAVE_EXPR);
          for (i = 0; i < nops; i++)
            {
              tree operand = TREE_OPERAND (exp, i);
              if (operand == NULL_TREE)
                continue;
              TREE_SET_CODE (exp, ERROR_MARK);
              if (!safe_from_p (x, operand, 0))
                return 0;
              TREE_SET_CODE (exp, SAVE_EXPR);
            }
          TREE_SET_CODE (exp, ERROR_MARK);
          return 1;

        case BIND_EXPR:
          /* The only operand we look at is operand 1.  The rest aren't
             part of the expression.  */
          return safe_from_p (x, TREE_OPERAND (exp, 1), 0);

        case METHOD_CALL_EXPR:
          /* This takes a rtx argument, but shouldn't appear here.  */
          abort ();
          
        default:
          break;
        }

      /* If we have an rtx, we do not need to scan our operands.  */
      if (exp_rtl)
        break;

      nops = TREE_CODE_LENGTH (TREE_CODE (exp));
      for (i = 0; i < nops; i++)
        if (TREE_OPERAND (exp, i) != 0
            && ! safe_from_p (x, TREE_OPERAND (exp, i), 0))
          return 0;
    }

  /* If we have an rtl, find any enclosed object.  Then see if we conflict
     with it.  */
  if (exp_rtl)
    {
      if (GET_CODE (exp_rtl) == SUBREG)
        {
          exp_rtl = SUBREG_REG (exp_rtl);
          if (GET_CODE (exp_rtl) == REG
              && REGNO (exp_rtl) < FIRST_PSEUDO_REGISTER)
            return 0;
        }

      /* If the rtl is X, then it is not safe.  Otherwise, it is unless both
         are memory and EXP is not readonly.  */
      return ! (rtx_equal_p (x, exp_rtl)
                || (GET_CODE (x) == MEM && GET_CODE (exp_rtl) == MEM
                    && ! TREE_READONLY (exp)));
    }

  /* If we reach here, it is safe.  */
  return 1;
}

/* Subroutine of expand_expr: return nonzero iff EXP is an
   expression whose type is statically determinable.  */

static int
fixed_type_p (exp)
     tree exp;
{
  if (TREE_CODE (exp) == PARM_DECL
      || TREE_CODE (exp) == VAR_DECL
      || TREE_CODE (exp) == CALL_EXPR || TREE_CODE (exp) == TARGET_EXPR
      || TREE_CODE (exp) == COMPONENT_REF
      || TREE_CODE (exp) == ARRAY_REF)
    return 1;
  return 0;
}

/* Subroutine of expand_expr: return rtx if EXP is a
   variable or parameter; else return 0.  */

static rtx
var_rtx (exp)
     tree exp;
{
  STRIP_NOPS (exp);
  switch (TREE_CODE (exp))
    {
    case PARM_DECL:
    case VAR_DECL:
      return DECL_RTL (exp);
    default:
      return 0;
    }
}

#ifdef MAX_INTEGER_COMPUTATION_MODE
void
check_max_integer_computation_mode (exp)
    tree exp;
{
  enum tree_code code;
  enum machine_mode mode;

  /* Strip any NOPs that don't change the mode.  */
  STRIP_NOPS (exp);
  code = TREE_CODE (exp);

  /* We must allow conversions of constants to MAX_INTEGER_COMPUTATION_MODE.  */
  if (code == NOP_EXPR
      && TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST)
    return;

  /* First check the type of the overall operation.   We need only look at
     unary, binary and relational operations.  */
  if (TREE_CODE_CLASS (code) == '1'
      || TREE_CODE_CLASS (code) == '2'
      || TREE_CODE_CLASS (code) == '<')
    {
      mode = TYPE_MODE (TREE_TYPE (exp));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && mode > MAX_INTEGER_COMPUTATION_MODE)
        fatal ("unsupported wide integer operation");
    }

  /* Check operand of a unary op.  */
  if (TREE_CODE_CLASS (code) == '1')
    {
      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && mode > MAX_INTEGER_COMPUTATION_MODE)
        fatal ("unsupported wide integer operation");
    }
        
  /* Check operands of a binary/comparison op.  */
  if (TREE_CODE_CLASS (code) == '2' || TREE_CODE_CLASS (code) == '<')
    {
      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && mode > MAX_INTEGER_COMPUTATION_MODE)
        fatal ("unsupported wide integer operation");

      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 1)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && mode > MAX_INTEGER_COMPUTATION_MODE)
        fatal ("unsupported wide integer operation");
    }
}
#endif

\f
/* Utility function used by expand_expr to see if TYPE, a RECORD_TYPE,
   has any readonly fields.  If any of the fields have types that
   contain readonly fields, return true as well.  */

static int
readonly_fields_p (type)
     tree type;
{
  tree field;

  for (field = TYPE_FIELDS (type); field != 0; field = TREE_CHAIN (field))
    if (TREE_CODE (field) == FIELD_DECL 
        && (TREE_READONLY (field)
            || (TREE_CODE (TREE_TYPE (field)) == RECORD_TYPE
                && readonly_fields_p (TREE_TYPE (field)))))
      return 1;

  return 0;
}
\f
/* expand_expr: generate code for computing expression EXP.
   An rtx for the computed value is returned.  The value is never null.
   In the case of a void EXP, const0_rtx is returned.

   The value may be stored in TARGET if TARGET is nonzero.
   TARGET is just a suggestion; callers must assume that
   the rtx returned may not be the same as TARGET.

   If TARGET is CONST0_RTX, it means that the value will be ignored.

   If TMODE is not VOIDmode, it suggests generating the
   result in mode TMODE.  But this is done only when convenient.
   Otherwise, TMODE is ignored and the value generated in its natural mode.
   TMODE is just a suggestion; callers must assume that
   the rtx returned may not have mode TMODE.

   Note that TARGET may have neither TMODE nor MODE.  In that case, it
   probably will not be used.

   If MODIFIER is EXPAND_SUM then when EXP is an addition
   we can return an rtx of the form (MULT (REG ...) (CONST_INT ...))
   or a nest of (PLUS ...) and (MINUS ...) where the terms are
   products as above, or REG or MEM, or constant.
   Ordinarily in such cases we would output mul or add instructions
   and then return a pseudo reg containing the sum.

   EXPAND_INITIALIZER is much like EXPAND_SUM except that
   it also marks a label as absolutely required (it can't be dead).
   It also makes a ZERO_EXTEND or SIGN_EXTEND instead of emitting extend insns.
   This is used for outputting expressions used in initializers.

   EXPAND_CONST_ADDRESS says that it is okay to return a MEM
   with a constant address even if that address is not normally legitimate.
   EXPAND_INITIALIZER and EXPAND_SUM also have this effect.  */

rtx
expand_expr (exp, target, tmode, modifier)
     register tree exp;
     rtx target;
     enum machine_mode tmode;
     enum expand_modifier modifier;
{
  register rtx op0, op1, temp;
  tree type = TREE_TYPE (exp);
  int unsignedp = TREE_UNSIGNED (type);
  register enum machine_mode mode;
  register enum tree_code code = TREE_CODE (exp);
  optab this_optab;
  rtx subtarget, original_target;
  int ignore;
  tree context;
  /* Used by check-memory-usage to make modifier read only.  */
  enum expand_modifier ro_modifier;

  /* Handle ERROR_MARK before anybody tries to access its type. */
  if (TREE_CODE (exp) == ERROR_MARK)
    {
      op0 = CONST0_RTX (tmode);
      if (op0 != 0)
        return op0;
      return const0_rtx;
    }

  mode = TYPE_MODE (type);
  /* Use subtarget as the target for operand 0 of a binary operation.  */
  subtarget = get_subtarget (target);
  original_target = target;
  ignore = (target == const0_rtx
            || ((code == NON_LVALUE_EXPR || code == NOP_EXPR
                 || code == CONVERT_EXPR || code == REFERENCE_EXPR
                 || code == COND_EXPR)
                && TREE_CODE (type) == VOID_TYPE));

  /* Make a read-only version of the modifier.  */
  if (modifier == EXPAND_NORMAL || modifier == EXPAND_SUM
      || modifier == EXPAND_CONST_ADDRESS || modifier == EXPAND_INITIALIZER)
    ro_modifier = modifier;
  else
    ro_modifier = EXPAND_NORMAL;

  /* If we are going to ignore this result, we need only do something
     if there is a side-effect somewhere in the expression.  If there
     is, short-circuit the most common cases here.  Note that we must
     not call expand_expr with anything but const0_rtx in case this
     is an initial expansion of a size that contains a PLACEHOLDER_EXPR.  */

  if (ignore)
    {
      if (! TREE_SIDE_EFFECTS (exp))
        return const0_rtx;

      /* Ensure we reference a volatile object even if value is ignored, but
         don't do this if all we are doing is taking its address.  */
      if (TREE_THIS_VOLATILE (exp)
          && TREE_CODE (exp) != FUNCTION_DECL
          && mode != VOIDmode && mode != BLKmode
          && modifier != EXPAND_CONST_ADDRESS)
        {
          temp = expand_expr (exp, NULL_RTX, VOIDmode, ro_modifier);
          if (GET_CODE (temp) == MEM)
            temp = copy_to_reg (temp);
          return const0_rtx;
        }

      if (TREE_CODE_CLASS (code) == '1' || code == COMPONENT_REF
          || code == INDIRECT_REF || code == BUFFER_REF)
        return expand_expr (TREE_OPERAND (exp, 0), const0_rtx,
                            VOIDmode, ro_modifier);
      else if (TREE_CODE_CLASS (code) == '2' || TREE_CODE_CLASS (code) == '<'
             || code == ARRAY_REF)
        {
          expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, ro_modifier);
          expand_expr (TREE_OPERAND (exp, 1), const0_rtx, VOIDmode, ro_modifier);
          return const0_rtx;
        }
      else if ((code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
               && ! TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 1)))
        /* If the second operand has no side effects, just evaluate
           the first.  */
        return expand_expr (TREE_OPERAND (exp, 0), const0_rtx,
                            VOIDmode, ro_modifier);
      else if (code == BIT_FIELD_REF)
        {
          expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, ro_modifier);
          expand_expr (TREE_OPERAND (exp, 1), const0_rtx, VOIDmode, ro_modifier);
          expand_expr (TREE_OPERAND (exp, 2), const0_rtx, VOIDmode, ro_modifier);
          return const0_rtx;
        }
;
      target = 0;
    }

#ifdef MAX_INTEGER_COMPUTATION_MODE
  /* Only check stuff here if the mode we want is different from the mode
     of the expression; if it's the same, check_max_integer_computiation_mode
     will handle it.  Do we really need to check this stuff at all?  */

  if (target
      && GET_MODE (target) != mode
      && TREE_CODE (exp) != INTEGER_CST
      && TREE_CODE (exp) != PARM_DECL
      && TREE_CODE (exp) != ARRAY_REF
      && TREE_CODE (exp) != COMPONENT_REF
      && TREE_CODE (exp) != BIT_FIELD_REF
      && TREE_CODE (exp) != INDIRECT_REF
      && TREE_CODE (exp) != CALL_EXPR
      && TREE_CODE (exp) != VAR_DECL
      && TREE_CODE (exp) != RTL_EXPR)
    {
      enum machine_mode mode = GET_MODE (target);

      if (GET_MODE_CLASS (mode) == MODE_INT
          && mode > MAX_INTEGER_COMPUTATION_MODE)
        fatal ("unsupported wide integer operation");
    }

  if (tmode != mode
      && TREE_CODE (exp) != INTEGER_CST
      && TREE_CODE (exp) != PARM_DECL
      && TREE_CODE (exp) != ARRAY_REF
      && TREE_CODE (exp) != COMPONENT_REF
      && TREE_CODE (exp) != BIT_FIELD_REF
      && TREE_CODE (exp) != INDIRECT_REF
      && TREE_CODE (exp) != VAR_DECL
      && TREE_CODE (exp) != CALL_EXPR
      && TREE_CODE (exp) != RTL_EXPR
      && GET_MODE_CLASS (tmode) == MODE_INT
      && tmode > MAX_INTEGER_COMPUTATION_MODE)
    fatal ("unsupported wide integer operation");

  check_max_integer_computation_mode (exp);
#endif

  /* If will do cse, generate all results into pseudo registers
     since 1) that allows cse to find more things
     and 2) otherwise cse could produce an insn the machine
     cannot support.  */

  if (! cse_not_expected && mode != BLKmode && target
      && (GET_CODE (target) != REG || REGNO (target) < FIRST_PSEUDO_REGISTER))
    target = subtarget;

  switch (code)
    {
    case LABEL_DECL:
      {
        tree function = decl_function_context (exp);
        /* Handle using a label in a containing function.  */
        if (function != current_function_decl
            && function != inline_function_decl && function != 0)
          {
            struct function *p = find_function_data (function);
            /* Allocate in the memory associated with the function
               that the label is in.  */
            push_obstacks (p->function_obstack,
                           p->function_maybepermanent_obstack);

            p->expr->x_forced_labels
              = gen_rtx_EXPR_LIST (VOIDmode, label_rtx (exp),
                                   p->expr->x_forced_labels);
            pop_obstacks ();
          }
        else
          {
            if (modifier == EXPAND_INITIALIZER)
              forced_labels = gen_rtx_EXPR_LIST (VOIDmode,
                                                 label_rtx (exp),
                                                 forced_labels);
          }

        temp = gen_rtx_MEM (FUNCTION_MODE,
                            gen_rtx_LABEL_REF (Pmode, label_rtx (exp)));
        if (function != current_function_decl
            && function != inline_function_decl && function != 0)
          LABEL_REF_NONLOCAL_P (XEXP (temp, 0)) = 1;
        return temp;
      }

    case PARM_DECL:
      if (DECL_RTL (exp) == 0)
        {
          error_with_decl (exp, "prior parameter's size depends on `%s'");
          return CONST0_RTX (mode);
        }

      /* ... fall through ...  */

    case VAR_DECL:
      /* If a static var's type was incomplete when the decl was written,
         but the type is complete now, lay out the decl now.  */
      if (DECL_SIZE (exp) == 0 && COMPLETE_TYPE_P (TREE_TYPE (exp))
          && (TREE_STATIC (exp) || DECL_EXTERNAL (exp)))
        {
          push_obstacks_nochange ();
          end_temporary_allocation ();
          layout_decl (exp, 0);
          PUT_MODE (DECL_RTL (exp), DECL_MODE (exp));
          pop_obstacks ();
        }

      /* Although static-storage variables start off initialized, according to
         ANSI C, a memcpy could overwrite them with uninitialized values.  So
         we check them too.  This also lets us check for read-only variables
         accessed via a non-const declaration, in case it won't be detected
         any other way (e.g., in an embedded system or OS kernel without
         memory protection).

         Aggregates are not checked here; they're handled elsewhere.  */
      if (cfun && current_function_check_memory_usage
          && code == VAR_DECL
          && GET_CODE (DECL_RTL (exp)) == MEM
          && ! AGGREGATE_TYPE_P (TREE_TYPE (exp)))
        {
          enum memory_use_mode memory_usage;
          memory_usage = get_memory_usage_from_modifier (modifier);

          in_check_memory_usage = 1;
          if (memory_usage != MEMORY_USE_DONT)
            emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                               XEXP (DECL_RTL (exp), 0), Pmode,
                               GEN_INT (int_size_in_bytes (type)),
                               TYPE_MODE (sizetype),
                               GEN_INT (memory_usage),
                               TYPE_MODE (integer_type_node));
          in_check_memory_usage = 0;
        }

      /* ... fall through ...  */

    case FUNCTION_DECL:
    case RESULT_DECL:
      if (DECL_RTL (exp) == 0)
        abort ();

      /* Ensure variable marked as used even if it doesn't go through
         a parser.  If it hasn't be used yet, write out an external
         definition.  */
      if (! TREE_USED (exp))
        {
          assemble_external (exp);
          TREE_USED (exp) = 1;
        }

      /* Show we haven't gotten RTL for this yet.  */
      temp = 0;

      /* Handle variables inherited from containing functions.  */
      context = decl_function_context (exp);

      /* We treat inline_function_decl as an alias for the current function
         because that is the inline function whose vars, types, etc.
         are being merged into the current function.
         See expand_inline_function.  */

      if (context != 0 && context != current_function_decl
          && context != inline_function_decl
          /* If var is static, we don't need a static chain to access it.  */
          && ! (GET_CODE (DECL_RTL (exp)) == MEM
                && CONSTANT_P (XEXP (DECL_RTL (exp), 0))))
        {
          rtx addr;

          /* Mark as non-local and addressable.  */
          DECL_NONLOCAL (exp) = 1;
          if (DECL_NO_STATIC_CHAIN (current_function_decl))
            abort ();
          mark_addressable (exp);
          if (GET_CODE (DECL_RTL (exp)) != MEM)
            abort ();
          addr = XEXP (DECL_RTL (exp), 0);
          if (GET_CODE (addr) == MEM)
            addr = change_address (addr, Pmode, 
                                   fix_lexical_addr (XEXP (addr, 0), exp));
          else
            addr = fix_lexical_addr (addr, exp);

          temp = change_address (DECL_RTL (exp), mode, addr);
        }

      /* This is the case of an array whose size is to be determined
         from its initializer, while the initializer is still being parsed.
         See expand_decl.  */

      else if (GET_CODE (DECL_RTL (exp)) == MEM
               && GET_CODE (XEXP (DECL_RTL (exp), 0)) == REG)
        temp = change_address (DECL_RTL (exp), GET_MODE (DECL_RTL (exp)),
                               XEXP (DECL_RTL (exp), 0));

      /* If DECL_RTL is memory, we are in the normal case and either
         the address is not valid or it is not a register and -fforce-addr
         is specified, get the address into a register.  */

      else if (GET_CODE (DECL_RTL (exp)) == MEM
               && modifier != EXPAND_CONST_ADDRESS
               && modifier != EXPAND_SUM
               && modifier != EXPAND_INITIALIZER
               && (! memory_address_p (DECL_MODE (exp),
                                       XEXP (DECL_RTL (exp), 0))
                   || (flag_force_addr
                       && GET_CODE (XEXP (DECL_RTL (exp), 0)) != REG)))
        temp = change_address (DECL_RTL (exp), VOIDmode,
                               copy_rtx (XEXP (DECL_RTL (exp), 0)));

      /* If we got something, return it.  But first, set the alignment
         the address is a register.  */
      if (temp != 0)
        {
          if (GET_CODE (temp) == MEM && GET_CODE (XEXP (temp, 0)) == REG)
            mark_reg_pointer (XEXP (temp, 0), DECL_ALIGN (exp));

          return temp;
        }

      /* If the mode of DECL_RTL does not match that of the decl, it
         must be a promoted value.  We return a SUBREG of the wanted mode,
         but mark it so that we know that it was already extended.  */

      if (GET_CODE (DECL_RTL (exp)) == REG
          && GET_MODE (DECL_RTL (exp)) != mode)
        {
          /* Get the signedness used for this variable.  Ensure we get the
             same mode we got when the variable was declared.  */
          if (GET_MODE (DECL_RTL (exp))
              != promote_mode (type, DECL_MODE (exp), &unsignedp, 0))
            abort ();

          temp = gen_rtx_SUBREG (mode, DECL_RTL (exp), 0);
          SUBREG_PROMOTED_VAR_P (temp) = 1;
          SUBREG_PROMOTED_UNSIGNED_P (temp) = unsignedp;
          return temp;
        }

      return DECL_RTL (exp);

    case INTEGER_CST:
      return immed_double_const (TREE_INT_CST_LOW (exp),
                                 TREE_INT_CST_HIGH (exp), mode);

    case CONST_DECL:
      return expand_expr (DECL_INITIAL (exp), target, VOIDmode,
                          EXPAND_MEMORY_USE_BAD);

    case REAL_CST:
      /* If optimized, generate immediate CONST_DOUBLE
         which will be turned into memory by reload if necessary. 
     
         We used to force a register so that loop.c could see it.  But
         this does not allow gen_* patterns to perform optimizations with
         the constants.  It also produces two insns in cases like "x = 1.0;".
         On most machines, floating-point constants are not permitted in
         many insns, so we'd end up copying it to a register in any case.

         Now, we do the copying in expand_binop, if appropriate.  */
      return immed_real_const (exp);

    case COMPLEX_CST:
    case STRING_CST:
      if (! TREE_CST_RTL (exp))
        output_constant_def (exp);

      /* TREE_CST_RTL probably contains a constant address.
         On RISC machines where a constant address isn't valid,
         make some insns to get that address into a register.  */
      if (GET_CODE (TREE_CST_RTL (exp)) == MEM
          && modifier != EXPAND_CONST_ADDRESS
          && modifier != EXPAND_INITIALIZER
          && modifier != EXPAND_SUM
          && (! memory_address_p (mode, XEXP (TREE_CST_RTL (exp), 0))
              || (flag_force_addr
                  && GET_CODE (XEXP (TREE_CST_RTL (exp), 0)) != REG)))
        return change_address (TREE_CST_RTL (exp), VOIDmode,
                               copy_rtx (XEXP (TREE_CST_RTL (exp), 0)));
      return TREE_CST_RTL (exp);

    case EXPR_WITH_FILE_LOCATION:
      {
        rtx to_return;
        const char *saved_input_filename = input_filename;
        int saved_lineno = lineno;
        input_filename = EXPR_WFL_FILENAME (exp);
        lineno = EXPR_WFL_LINENO (exp);
        if (EXPR_WFL_EMIT_LINE_NOTE (exp))
          emit_line_note (input_filename, lineno);
        /* Possibly avoid switching back and force here */
        to_return = expand_expr (EXPR_WFL_NODE (exp), target, tmode, modifier);
        input_filename = saved_input_filename;
        lineno = saved_lineno;
        return to_return;
      }

    case SAVE_EXPR:
      context = decl_function_context (exp);

      /* If this SAVE_EXPR was at global context, assume we are an
         initialization function and move it into our context.  */
      if (context == 0)
        SAVE_EXPR_CONTEXT (exp) = current_function_decl;

      /* We treat inline_function_decl as an alias for the current function
         because that is the inline function whose vars, types, etc.
         are being merged into the current function.
         See expand_inline_function.  */
      if (context == current_function_decl || context == inline_function_decl)
        context = 0;

      /* If this is non-local, handle it.  */
      if (context)
        {
          /* The following call just exists to abort if the context is
             not of a containing function.  */
          find_function_data (context);

          temp = SAVE_EXPR_RTL (exp);
          if (temp && GET_CODE (temp) == REG)
            {
              put_var_into_stack (exp);
              temp = SAVE_EXPR_RTL (exp);
            }
          if (temp == 0 || GET_CODE (temp) != MEM)
            abort ();
          return change_address (temp, mode,
                                 fix_lexical_addr (XEXP (temp, 0), exp));
        }
      if (SAVE_EXPR_RTL (exp) == 0)
        {
          if (mode == VOIDmode)
            temp = const0_rtx;
          else
            temp = assign_temp (type, 3, 0, 0);

          SAVE_EXPR_RTL (exp) = temp;
          if (!optimize && GET_CODE (temp) == REG)
            save_expr_regs = gen_rtx_EXPR_LIST (VOIDmode, temp,
                                                save_expr_regs);

          /* If the mode of TEMP does not match that of the expression, it
             must be a promoted value.  We pass store_expr a SUBREG of the
             wanted mode but mark it so that we know that it was already
             extended.  Note that `unsignedp' was modified above in
             this case.  */

          if (GET_CODE (temp) == REG && GET_MODE (temp) != mode)
            {
              temp = gen_rtx_SUBREG (mode, SAVE_EXPR_RTL (exp), 0);
              SUBREG_PROMOTED_VAR_P (temp) = 1;
              SUBREG_PROMOTED_UNSIGNED_P (temp) = unsignedp;
            }

          if (temp == const0_rtx)
            expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode,
                         EXPAND_MEMORY_USE_BAD);
          else
            store_expr (TREE_OPERAND (exp, 0), temp, 0);

          TREE_USED (exp) = 1;
        }

      /* If the mode of SAVE_EXPR_RTL does not match that of the expression, it
         must be a promoted value.  We return a SUBREG of the wanted mode,
         but mark it so that we know that it was already extended.  */

      if (GET_CODE (SAVE_EXPR_RTL (exp)) == REG
          && GET_MODE (SAVE_EXPR_RTL (exp)) != mode)
        {
          /* Compute the signedness and make the proper SUBREG.  */
          promote_mode (type, mode, &unsignedp, 0);
          temp = gen_rtx_SUBREG (mode, SAVE_EXPR_RTL (exp), 0);
          SUBREG_PROMOTED_VAR_P (temp) = 1;
          SUBREG_PROMOTED_UNSIGNED_P (temp) = unsignedp;
          return temp;
        }

      return SAVE_EXPR_RTL (exp);

    case UNSAVE_EXPR:
      {
        rtx temp;
        temp = expand_expr (TREE_OPERAND (exp, 0), target, tmode, modifier);
        TREE_OPERAND (exp, 0) = unsave_expr_now (TREE_OPERAND (exp, 0));
        return temp;
      }

    case PLACEHOLDER_EXPR:
      {
        tree placeholder_expr;

        /* If there is an object on the head of the placeholder list,
           see if some object in it of type TYPE or a pointer to it.  For
           further information, see tree.def.  */
        for (placeholder_expr = placeholder_list;
             placeholder_expr != 0;
             placeholder_expr = TREE_CHAIN (placeholder_expr))
          {
            tree need_type = TYPE_MAIN_VARIANT (type);
            tree object = 0;
            tree old_list = placeholder_list;
            tree elt;

            /* Find the outermost reference that is of the type we want.
               If none, see if any object has a type that is a pointer to 
               the type we want.  */
            for (elt = TREE_PURPOSE (placeholder_expr);
                 elt != 0 && object == 0;
                 elt
                 = ((TREE_CODE (elt) == COMPOUND_EXPR
                     || TREE_CODE (elt) == COND_EXPR)
                    ? TREE_OPERAND (elt, 1)
                    : (TREE_CODE_CLASS (TREE_CODE (elt)) == 'r'
                       || TREE_CODE_CLASS (TREE_CODE (elt)) == '1'
                       || TREE_CODE_CLASS (TREE_CODE (elt)) == '2'
                       || TREE_CODE_CLASS (TREE_CODE (elt)) == 'e')
                    ? TREE_OPERAND (elt, 0) : 0))
              if (TYPE_MAIN_VARIANT (TREE_TYPE (elt)) == need_type)
                object = elt;

            for (elt = TREE_PURPOSE (placeholder_expr);
                 elt != 0 && object == 0;
                 elt
                 = ((TREE_CODE (elt) == COMPOUND_EXPR
                     || TREE_CODE (elt) == COND_EXPR)
                    ? TREE_OPERAND (elt, 1)
                    : (TREE_CODE_CLASS (TREE_CODE (elt)) == 'r'
                       || TREE_CODE_CLASS (TREE_CODE (elt)) == '1'
                       || TREE_CODE_CLASS (TREE_CODE (elt)) == '2'
                       || TREE_CODE_CLASS (TREE_CODE (elt)) == 'e')
                    ? TREE_OPERAND (elt, 0) : 0))
              if (POINTER_TYPE_P (TREE_TYPE (elt))
                  && (TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (elt)))
                      == need_type))
                object = build1 (INDIRECT_REF, need_type, elt);

            if (object != 0)
              {
                /* Expand this object skipping the list entries before
                   it was found in case it is also a PLACEHOLDER_EXPR.
                   In that case, we want to translate it using subsequent
                   entries.  */
                placeholder_list = TREE_CHAIN (placeholder_expr);
                temp = expand_expr (object, original_target, tmode,
                                    ro_modifier);
                placeholder_list = old_list;
                return temp;
              }
          }
      }

      /* We can't find the object or there was a missing WITH_RECORD_EXPR.  */
      abort ();

    case WITH_RECORD_EXPR:
      /* Put the object on the placeholder list, expand our first operand,
         and pop the list.  */
      placeholder_list = tree_cons (TREE_OPERAND (exp, 1), NULL_TREE,
                                    placeholder_list);
      target = expand_expr (TREE_OPERAND (exp, 0), original_target,
                            tmode, ro_modifier);
      placeholder_list = TREE_CHAIN (placeholder_list);
      return target;

    case GOTO_EXPR:
      if (TREE_CODE (TREE_OPERAND (exp, 0)) == LABEL_DECL)
        expand_goto (TREE_OPERAND (exp, 0));
      else
        expand_computed_goto (TREE_OPERAND (exp, 0));
      return const0_rtx;

    case EXIT_EXPR:
      expand_exit_loop_if_false (NULL_PTR,
                                 invert_truthvalue (TREE_OPERAND (exp, 0)));
      return const0_rtx;

    case LABELED_BLOCK_EXPR:
      if (LABELED_BLOCK_BODY (exp))
        expand_expr_stmt (LABELED_BLOCK_BODY (exp));
      emit_label (label_rtx (LABELED_BLOCK_LABEL (exp)));
      return const0_rtx;

    case EXIT_BLOCK_EXPR:
      if (EXIT_BLOCK_RETURN (exp))
        sorry ("returned value in block_exit_expr");
      expand_goto (LABELED_BLOCK_LABEL (EXIT_BLOCK_LABELED_BLOCK (exp)));
      return const0_rtx;

    case LOOP_EXPR:
      push_temp_slots ();
      expand_start_loop (1);
      expand_expr_stmt (TREE_OPERAND (exp, 0));
      expand_end_loop ();
      pop_temp_slots ();

      return const0_rtx;

    case BIND_EXPR:
      {
        tree vars = TREE_OPERAND (exp, 0);
        int vars_need_expansion = 0;

        /* Need to open a binding contour here because
           if there are any cleanups they must be contained here.  */
        expand_start_bindings (2);

        /* Mark the corresponding BLOCK for output in its proper place.  */
        if (TREE_OPERAND (exp, 2) != 0
            && ! TREE_USED (TREE_OPERAND (exp, 2)))
          insert_block (TREE_OPERAND (exp, 2));

        /* If VARS have not yet been expanded, expand them now.  */
        while (vars)
          {
            if (DECL_RTL (vars) == 0)
              {
                vars_need_expansion = 1;
                expand_decl (vars);
              }
            expand_decl_init (vars);
            vars = TREE_CHAIN (vars);
          }

        temp = expand_expr (TREE_OPERAND (exp, 1), target, tmode, ro_modifier);

        expand_end_bindings (TREE_OPERAND (exp, 0), 0, 0);

        return temp;
      }

    case RTL_EXPR:
      if (RTL_EXPR_SEQUENCE (exp))
        {
          if (RTL_EXPR_SEQUENCE (exp) == const0_rtx)
            abort ();
          emit_insns (RTL_EXPR_SEQUENCE (exp));
          RTL_EXPR_SEQUENCE (exp) = const0_rtx;
        }
      preserve_rtl_expr_result (RTL_EXPR_RTL (exp));
      free_temps_for_rtl_expr (exp);
      return RTL_EXPR_RTL (exp);

    case CONSTRUCTOR:
      /* If we don't need the result, just ensure we evaluate any
         subexpressions.  */
      if (ignore)
        {
          tree elt;
          for (elt = CONSTRUCTOR_ELTS (exp); elt; elt = TREE_CHAIN (elt))
            expand_expr (TREE_VALUE (elt), const0_rtx, VOIDmode,
                         EXPAND_MEMORY_USE_BAD);
          return const0_rtx;
        }

      /* All elts simple constants => refer to a constant in memory.  But
         if this is a non-BLKmode mode, let it store a field at a time
         since that should make a CONST_INT or CONST_DOUBLE when we
         fold.  Likewise, if we have a target we can use, it is best to
         store directly into the target unless the type is large enough
         that memcpy will be used.  If we are making an initializer and
         all operands are constant, put it in memory as well.  */
      else if ((TREE_STATIC (exp)
                && ((mode == BLKmode
                     && ! (target != 0 && safe_from_p (target, exp, 1)))
                    || TREE_ADDRESSABLE (exp)
                    || (host_integerp (TYPE_SIZE_UNIT (type), 1)
                        && (! MOVE_BY_PIECES_P 
                            (tree_low_cst (TYPE_SIZE_UNIT (type), 1),
                             TYPE_ALIGN (type)))
                        && ! mostly_zeros_p (exp))))
               || (modifier == EXPAND_INITIALIZER && TREE_CONSTANT (exp)))
        {
          rtx constructor = output_constant_def (exp);

          if (modifier != EXPAND_CONST_ADDRESS
              && modifier != EXPAND_INITIALIZER
              && modifier != EXPAND_SUM
              && (! memory_address_p (GET_MODE (constructor),
                                      XEXP (constructor, 0))
                  || (flag_force_addr
                      && GET_CODE (XEXP (constructor, 0)) != REG)))
            constructor = change_address (constructor, VOIDmode,
                                          XEXP (constructor, 0));
          return constructor;
        }

      else
        {
          /* Handle calls that pass values in multiple non-contiguous
             locations.  The Irix 6 ABI has examples of this.  */
          if (target == 0 || ! safe_from_p (target, exp, 1)
              || GET_CODE (target) == PARALLEL)
            {
              if (mode != BLKmode && ! TREE_ADDRESSABLE (exp))
                target = gen_reg_rtx (tmode != VOIDmode ? tmode : mode);
              else
                target = assign_temp (type, 0, 1, 1);
            }

          if (TREE_READONLY (exp))
            {
              if (GET_CODE (target) == MEM)
                target = copy_rtx (target);

              RTX_UNCHANGING_P (target) = 1;
            }

          store_constructor (exp, target, TYPE_ALIGN (TREE_TYPE (exp)), 0,
                             int_size_in_bytes (TREE_TYPE (exp)));
          return target;
        }

    case INDIRECT_REF:
      {
        tree exp1 = TREE_OPERAND (exp, 0);
        tree index;
        tree string = string_constant (exp1, &index);
 
        /* Try to optimize reads from const strings.  */
        if (string
            && TREE_CODE (string) == STRING_CST
            && TREE_CODE (index) == INTEGER_CST
            && compare_tree_int (index, TREE_STRING_LENGTH (string)) < 0
            && GET_MODE_CLASS (mode) == MODE_INT
            && GET_MODE_SIZE (mode) == 1
            && modifier != EXPAND_MEMORY_USE_WO)
          return
            GEN_INT (TREE_STRING_POINTER (string)[TREE_INT_CST_LOW (index)]);

        op0 = expand_expr (exp1, NULL_RTX, VOIDmode, EXPAND_SUM);
        op0 = memory_address (mode, op0);

        if (cfun && current_function_check_memory_usage
            && ! AGGREGATE_TYPE_P (TREE_TYPE (exp)))
          {
            enum memory_use_mode memory_usage;
            memory_usage = get_memory_usage_from_modifier (modifier);

            if (memory_usage != MEMORY_USE_DONT)
              {
                in_check_memory_usage = 1;
                emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                                   op0, Pmode,
                                   GEN_INT (int_size_in_bytes (type)),
                                   TYPE_MODE (sizetype),
                                   GEN_INT (memory_usage),
                                   TYPE_MODE (integer_type_node));
                in_check_memory_usage = 0;
              }
          }

        temp = gen_rtx_MEM (mode, op0);
        set_mem_attributes (temp, exp, 0);

        /* It is incorrect to set RTX_UNCHANGING_P from TREE_READONLY
           here, because, in C and C++, the fact that a location is accessed
           through a pointer to const does not mean that the value there can
           never change.  Languages where it can never change should
           also set TREE_STATIC.  */
        RTX_UNCHANGING_P (temp) = TREE_READONLY (exp) & TREE_STATIC (exp);

        /* If we are writing to this object and its type is a record with
           readonly fields, we must mark it as readonly so it will
           conflict with readonly references to those fields.  */
        if (modifier == EXPAND_MEMORY_USE_WO
            && TREE_CODE (type) == RECORD_TYPE && readonly_fields_p (type))
          RTX_UNCHANGING_P (temp) = 1;

        return temp;
      }

    case ARRAY_REF:
      if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) != ARRAY_TYPE)
        abort ();

      {
        tree array = TREE_OPERAND (exp, 0);
        tree domain = TYPE_DOMAIN (TREE_TYPE (array));
        tree low_bound = domain ? TYPE_MIN_VALUE (domain) : integer_zero_node;
        tree index = convert (sizetype, TREE_OPERAND (exp, 1));
        HOST_WIDE_INT i;

        /* Optimize the special-case of a zero lower bound.

           We convert the low_bound to sizetype to avoid some problems
           with constant folding.  (E.g. suppose the lower bound is 1,
           and its mode is QI.  Without the conversion,  (ARRAY
           +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
           +INDEX), which becomes (ARRAY+255+INDEX).  Oops!)  */

        if (! integer_zerop (low_bound))
          index = size_diffop (index, convert (sizetype, low_bound));

        /* Fold an expression like: "foo"[2].
           This is not done in fold so it won't happen inside &.
           Don't fold if this is for wide characters since it's too
           difficult to do correctly and this is a very rare case.  */

        if (TREE_CODE (array) == STRING_CST
            && TREE_CODE (index) == INTEGER_CST
            && compare_tree_int (index, TREE_STRING_LENGTH (array)) < 0
            && GET_MODE_CLASS (mode) == MODE_INT
            && GET_MODE_SIZE (mode) == 1)
          return
            GEN_INT (TREE_STRING_POINTER (array)[TREE_INT_CST_LOW (index)]);

        /* If this is a constant index into a constant array,
           just get the value from the array.  Handle both the cases when
           we have an explicit constructor and when our operand is a variable
           that was declared const.  */

        if (TREE_CODE (array) == CONSTRUCTOR && ! TREE_SIDE_EFFECTS (array)
            && TREE_CODE (index) == INTEGER_CST
            && 0 > compare_tree_int (index, 
                                     list_length (CONSTRUCTOR_ELTS
                                                  (TREE_OPERAND (exp, 0)))))
          {
            tree elem;

            for (elem = CONSTRUCTOR_ELTS (TREE_OPERAND (exp, 0)),
                 i = TREE_INT_CST_LOW (index);
                 elem != 0 && i != 0; i--, elem = TREE_CHAIN (elem))
              ;

            if (elem)
              return expand_expr (fold (TREE_VALUE (elem)), target,
                                  tmode, ro_modifier);
          }
          
        else if (optimize >= 1
                 && TREE_READONLY (array) && ! TREE_SIDE_EFFECTS (array)
                 && TREE_CODE (array) == VAR_DECL && DECL_INITIAL (array)
                 && TREE_CODE (DECL_INITIAL (array)) != ERROR_MARK)
          {
            if (TREE_CODE (index) == INTEGER_CST)
              {
                tree init = DECL_INITIAL (array);

                if (TREE_CODE (init) == CONSTRUCTOR)
                  {
                    tree elem;

                    for (elem = CONSTRUCTOR_ELTS (init);
                         (elem
                          && !tree_int_cst_equal (TREE_PURPOSE (elem), index));
                         elem = TREE_CHAIN (elem))
                      ;

                    if (elem)
                      return expand_expr (fold (TREE_VALUE (elem)), target,
                                          tmode, ro_modifier);
                  }
                else if (TREE_CODE (init) == STRING_CST
                         && 0 > compare_tree_int (index,
                                                  TREE_STRING_LENGTH (init)))
                  return (GEN_INT
                          (TREE_STRING_POINTER
                           (init)[TREE_INT_CST_LOW (index)]));
              }
          }
      }

      /* ... fall through ... */

    case COMPONENT_REF:
    case BIT_FIELD_REF:
      /* If the operand is a CONSTRUCTOR, we can just extract the
         appropriate field if it is present.  Don't do this if we have
         already written the data since we want to refer to that copy
         and varasm.c assumes that's what we'll do.  */
      if (code != ARRAY_REF
          && TREE_CODE (TREE_OPERAND (exp, 0)) == CONSTRUCTOR
          && TREE_CST_RTL (TREE_OPERAND (exp, 0)) == 0)
        {
          tree elt;

          for (elt = CONSTRUCTOR_ELTS (TREE_OPERAND (exp, 0)); elt;
               elt = TREE_CHAIN (elt))
            if (TREE_PURPOSE (elt) == TREE_OPERAND (exp, 1)
                /* We can normally use the value of the field in the
                   CONSTRUCTOR.  However, if this is a bitfield in
                   an integral mode that we can fit in a HOST_WIDE_INT,
                   we must mask only the number of bits in the bitfield,
                   since this is done implicitly by the constructor.  If
                   the bitfield does not meet either of those conditions,
                   we can't do this optimization.  */
                && (! DECL_BIT_FIELD (TREE_PURPOSE (elt))
                    || ((GET_MODE_CLASS (DECL_MODE (TREE_PURPOSE (elt)))
                         == MODE_INT)
                        && (GET_MODE_BITSIZE (DECL_MODE (TREE_PURPOSE (elt)))
                            <= HOST_BITS_PER_WIDE_INT))))
              {
                op0 =  expand_expr (TREE_VALUE (elt), target, tmode, modifier);
                if (DECL_BIT_FIELD (TREE_PURPOSE (elt)))
                  {
                    HOST_WIDE_INT bitsize
                      = TREE_INT_CST_LOW (DECL_SIZE (TREE_PURPOSE (elt)));

                    if (TREE_UNSIGNED (TREE_TYPE (TREE_PURPOSE (elt))))
                      {
                        op1 = GEN_INT (((HOST_WIDE_INT) 1 << bitsize) - 1);
                        op0 = expand_and (op0, op1, target);
                      }
                    else
                      {
                        enum machine_mode imode
                          = TYPE_MODE (TREE_TYPE (TREE_PURPOSE (elt)));
                        tree count
                          = build_int_2 (GET_MODE_BITSIZE (imode) - bitsize,
                                         0);

                        op0 = expand_shift (LSHIFT_EXPR, imode, op0, count,
                                            target, 0);
                        op0 = expand_shift (RSHIFT_EXPR, imode, op0, count,
                                            target, 0);
                      }
                  }

                return op0;
              }
        }

      {
        enum machine_mode mode1;
        HOST_WIDE_INT bitsize, bitpos;
        tree offset;
        int volatilep = 0;
        unsigned int alignment;
        tree tem = get_inner_reference (exp, &bitsize, &bitpos, &offset,
                                        &mode1, &unsignedp, &volatilep,
                                        &alignment);

        /* If we got back the original object, something is wrong.  Perhaps
           we are evaluating an expression too early.  In any event, don't
           infinitely recurse.  */
        if (tem == exp)
          abort ();

        /* If TEM's type is a union of variable size, pass TARGET to the inner
           computation, since it will need a temporary and TARGET is known
           to have to do.  This occurs in unchecked conversion in Ada.  */
  
        op0 = expand_expr (tem,
                           (TREE_CODE (TREE_TYPE (tem)) == UNION_TYPE
                            && (TREE_CODE (TYPE_SIZE (TREE_TYPE (tem)))
                                != INTEGER_CST)
                            ? target : NULL_RTX),
                           VOIDmode,
                           (modifier == EXPAND_INITIALIZER
                            || modifier == EXPAND_CONST_ADDRESS)
                           ? modifier : EXPAND_NORMAL);

        /* If this is a constant, put it into a register if it is a
           legitimate constant and OFFSET is 0 and memory if it isn't.  */
        if (CONSTANT_P (op0))
          {
            enum machine_mode mode = TYPE_MODE (TREE_TYPE (tem));
            if (mode != BLKmode && LEGITIMATE_CONSTANT_P (op0)
                && offset == 0)
              op0 = force_reg (mode, op0);
            else
              op0 = validize_mem (force_const_mem (mode, op0));
          }

        if (offset != 0)
          {
            rtx offset_rtx = expand_expr (offset, NULL_RTX, VOIDmode, 0);

            /* If this object is in memory, put it into a register.
               This case can't occur in C, but can in Ada if we have
               unchecked conversion of an expression from a scalar type to
               an array or record type.  */
            if (GET_CODE (op0) == REG || GET_CODE (op0) == SUBREG
                || GET_CODE (op0) == CONCAT || GET_CODE (op0) == ADDRESSOF)
              {
                rtx memloc = assign_temp (TREE_TYPE (tem), 1, 1, 1);

                mark_temp_addr_taken (memloc);
                emit_move_insn (memloc, op0);
                op0 = memloc;
              }

            if (GET_CODE (op0) != MEM)
              abort ();

            if (GET_MODE (offset_rtx) != ptr_mode)
              {
#ifdef POINTERS_EXTEND_UNSIGNED
                offset_rtx = convert_memory_address (ptr_mode, offset_rtx);
#else
                offset_rtx = convert_to_mode (ptr_mode, offset_rtx, 0);
#endif
              }

            /* A constant address in OP0 can have VOIDmode, we must not try
               to call force_reg for that case.  Avoid that case.  */
            if (GET_CODE (op0) == MEM
                && GET_MODE (op0) == BLKmode
                && GET_MODE (XEXP (op0, 0)) != VOIDmode
                && bitsize != 0
                && (bitpos % bitsize) == 0 
                && (bitsize % GET_MODE_ALIGNMENT (mode1)) == 0
                && alignment == GET_MODE_ALIGNMENT (mode1))
              {
                rtx temp = change_address (op0, mode1,
                                           plus_constant (XEXP (op0, 0),
                                                          (bitpos /
                                                           BITS_PER_UNIT)));
                if (GET_CODE (XEXP (temp, 0)) == REG)
                  op0 = temp;
                else
                  op0 = change_address (op0, mode1,
                                        force_reg (GET_MODE (XEXP (temp, 0)),
                                                   XEXP (temp, 0)));
                bitpos = 0;
              }


            op0 = change_address (op0, VOIDmode,
                                  gen_rtx_PLUS (ptr_mode, XEXP (op0, 0),
                                                force_reg (ptr_mode,
                                                           offset_rtx)));
          }

        /* Don't forget about volatility even if this is a bitfield.  */
        if (GET_CODE (op0) == MEM && volatilep && ! MEM_VOLATILE_P (op0))
          {
            op0 = copy_rtx (op0);
            MEM_VOLATILE_P (op0) = 1;
          }

        /* Check the access.  */
        if (cfun != 0 && current_function_check_memory_usage
            && GET_CODE (op0) == MEM)
          {
            enum memory_use_mode memory_usage;
            memory_usage = get_memory_usage_from_modifier (modifier);

            if (memory_usage != MEMORY_USE_DONT)
              {
                rtx to;
                int size;

                to = plus_constant (XEXP (op0, 0), (bitpos / BITS_PER_UNIT));
                size = (bitpos % BITS_PER_UNIT) + bitsize + BITS_PER_UNIT - 1;

                /* Check the access right of the pointer.  */
                in_check_memory_usage = 1;
                if (size > BITS_PER_UNIT)
                  emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                                     to, Pmode,
                                     GEN_INT (size / BITS_PER_UNIT),
                                     TYPE_MODE (sizetype),
                                     GEN_INT (memory_usage), 
                                     TYPE_MODE (integer_type_node));
                in_check_memory_usage = 0;
              }
          }

        /* In cases where an aligned union has an unaligned object
           as a field, we might be extracting a BLKmode value from
           an integer-mode (e.g., SImode) object.  Handle this case
           by doing the extract into an object as wide as the field
           (which we know to be the width of a basic mode), then
           storing into memory, and changing the mode to BLKmode.
           If we ultimately want the address (EXPAND_CONST_ADDRESS or
           EXPAND_INITIALIZER), then we must not copy to a temporary.  */
        if (mode1 == VOIDmode
            || GET_CODE (op0) == REG || GET_CODE (op0) == SUBREG
            || (modifier != EXPAND_CONST_ADDRESS
                && modifier != EXPAND_INITIALIZER
                && ((mode1 != BLKmode && ! direct_load[(int) mode1]
                     && GET_MODE_CLASS (mode) != MODE_COMPLEX_INT
                     && GET_MODE_CLASS (mode) != MODE_COMPLEX_FLOAT)
                    /* If the field isn't aligned enough to fetch as a memref,
                       fetch it as a bit field.  */
                    || (mode1 != BLKmode
                        && SLOW_UNALIGNED_ACCESS (mode1, alignment)
                        && ((TYPE_ALIGN (TREE_TYPE (tem))
                             < GET_MODE_ALIGNMENT (mode))
                            || (bitpos % GET_MODE_ALIGNMENT (mode) != 0)))
                    /* If the type and the field are a constant size and the
                       size of the type isn't the same size as the bitfield,
                       we must use bitfield operations.  */
                    || ((bitsize >= 0
                         && (TREE_CODE (TYPE_SIZE (TREE_TYPE (exp)))
                             == INTEGER_CST)
                         && 0 != compare_tree_int (TYPE_SIZE (TREE_TYPE (exp)),
                                                   bitsize)))))
            || (modifier != EXPAND_CONST_ADDRESS
                && modifier != EXPAND_INITIALIZER
                && mode == BLKmode
                && SLOW_UNALIGNED_ACCESS (mode, alignment)
                && (TYPE_ALIGN (type) > alignment
                    || bitpos % TYPE_ALIGN (type) != 0)))
          {
            enum machine_mode ext_mode = mode;

            if (ext_mode == BLKmode
                && ! (target != 0 && GET_CODE (op0) == MEM
                      && GET_CODE (target) == MEM
                      && bitpos % BITS_PER_UNIT == 0))
              ext_mode = mode_for_size (bitsize, MODE_INT, 1);

            if (ext_mode == BLKmode)
              {
                /* In this case, BITPOS must start at a byte boundary and
                   TARGET, if specified, must be a MEM.  */
                if (GET_CODE (op0) != MEM
                    || (target != 0 && GET_CODE (target) != MEM)
                    || bitpos % BITS_PER_UNIT != 0)
                  abort ();

                op0 = change_address (op0, VOIDmode,
                                      plus_constant (XEXP (op0, 0),
                                                     bitpos / BITS_PER_UNIT));
                if (target == 0)
                  target = assign_temp (type, 0, 1, 1);

                emit_block_move (target, op0,
                                 GEN_INT ((bitsize + BITS_PER_UNIT - 1)
                                          / BITS_PER_UNIT),
                                 BITS_PER_UNIT);
                
                return target;
              }

            op0 = validize_mem (op0);

            if (GET_CODE (op0) == MEM && GET_CODE (XEXP (op0, 0)) == REG)
              mark_reg_pointer (XEXP (op0, 0), alignment);

            op0 = extract_bit_field (op0, bitsize, bitpos,
                                     unsignedp, target, ext_mode, ext_mode,
                                     alignment,
                                     int_size_in_bytes (TREE_TYPE (tem)));

            /* If the result is a record type and BITSIZE is narrower than
               the mode of OP0, an integral mode, and this is a big endian
               machine, we must put the field into the high-order bits.  */
            if (TREE_CODE (type) == RECORD_TYPE && BYTES_BIG_ENDIAN
                && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
                && bitsize < GET_MODE_BITSIZE (GET_MODE (op0)))
              op0 = expand_shift (LSHIFT_EXPR, GET_MODE (op0), op0,
                                  size_int (GET_MODE_BITSIZE (GET_MODE (op0))
                                            - bitsize),
                                  op0, 1);

            if (mode == BLKmode)
              {
                rtx new = assign_stack_temp (ext_mode,
                                             bitsize / BITS_PER_UNIT, 0);

                emit_move_insn (new, op0);
                op0 = copy_rtx (new);
                PUT_MODE (op0, BLKmode);
                MEM_SET_IN_STRUCT_P (op0, 1);
              }

            return op0;
          }

        /* If the result is BLKmode, use that to access the object
           now as well.  */
        if (mode == BLKmode)
          mode1 = BLKmode;

        /* Get a reference to just this component.  */
        if (modifier == EXPAND_CONST_ADDRESS
            || modifier == EXPAND_SUM || modifier == EXPAND_INITIALIZER)
          op0 = gen_rtx_MEM (mode1, plus_constant (XEXP (op0, 0),
                                                   (bitpos / BITS_PER_UNIT)));
        else
          op0 = change_address (op0, mode1,
                                plus_constant (XEXP (op0, 0),
                                               (bitpos / BITS_PER_UNIT)));

        set_mem_attributes (op0, exp, 0);
        if (GET_CODE (XEXP (op0, 0)) == REG)
          mark_reg_pointer (XEXP (op0, 0), alignment);

        MEM_VOLATILE_P (op0) |= volatilep;
        if (mode == mode1 || mode1 == BLKmode || mode1 == tmode
            || modifier == EXPAND_CONST_ADDRESS
            || modifier == EXPAND_INITIALIZER)
          return op0;
        else if (target == 0)
          target = gen_reg_rtx (tmode != VOIDmode ? tmode : mode);

        convert_move (target, op0, unsignedp);
        return target;
      }

      /* Intended for a reference to a buffer of a file-object in Pascal.
         But it's not certain that a special tree code will really be
         necessary for these.  INDIRECT_REF might work for them.  */
    case BUFFER_REF:
      abort ();

    case IN_EXPR:
      {
        /* Pascal set IN expression.

           Algorithm:
               rlo       = set_low - (set_low%bits_per_word);
               the_word  = set [ (index - rlo)/bits_per_word ];
               bit_index = index % bits_per_word;
               bitmask   = 1 << bit_index;
               return !!(the_word & bitmask);  */

        tree set = TREE_OPERAND (exp, 0);
        tree index = TREE_OPERAND (exp, 1);
        int iunsignedp = TREE_UNSIGNED (TREE_TYPE (index));
        tree set_type = TREE_TYPE (set);
        tree set_low_bound = TYPE_MIN_VALUE (TYPE_DOMAIN (set_type));
        tree set_high_bound = TYPE_MAX_VALUE (TYPE_DOMAIN (set_type));
        rtx index_val = expand_expr (index, 0, VOIDmode, 0);
        rtx lo_r = expand_expr (set_low_bound, 0, VOIDmode, 0);
        rtx hi_r = expand_expr (set_high_bound, 0, VOIDmode, 0);
        rtx setval = expand_expr (set, 0, VOIDmode, 0);
        rtx setaddr = XEXP (setval, 0);
        enum machine_mode index_mode = TYPE_MODE (TREE_TYPE (index));
        rtx rlow;
        rtx diff, quo, rem, addr, bit, result;

        preexpand_calls (exp);

        /* If domain is empty, answer is no.  Likewise if index is constant
           and out of bounds.  */
        if (((TREE_CODE (set_high_bound) == INTEGER_CST
             && TREE_CODE (set_low_bound) == INTEGER_CST
             && tree_int_cst_lt (set_high_bound, set_low_bound))
             || (TREE_CODE (index) == INTEGER_CST
                 && TREE_CODE (set_low_bound) == INTEGER_CST
                 && tree_int_cst_lt (index, set_low_bound))
             || (TREE_CODE (set_high_bound) == INTEGER_CST
                 && TREE_CODE (index) == INTEGER_CST
                 && tree_int_cst_lt (set_high_bound, index))))
          return const0_rtx;

        if (target == 0)
          target = gen_reg_rtx (tmode != VOIDmode ? tmode : mode);

        /* If we get here, we have to generate the code for both cases
           (in range and out of range).  */

        op0 = gen_label_rtx ();
        op1 = gen_label_rtx ();

        if (! (GET_CODE (index_val) == CONST_INT
               && GET_CODE (lo_r) == CONST_INT))
          {
            emit_cmp_and_jump_insns (index_val, lo_r, LT, NULL_RTX,
                                     GET_MODE (index_val), iunsignedp, 0, op1);
          }

        if (! (GET_CODE (index_val) == CONST_INT
               && GET_CODE (hi_r) == CONST_INT))
          {
            emit_cmp_and_jump_insns (index_val, hi_r, GT, NULL_RTX,
                                     GET_MODE (index_val), iunsignedp, 0, op1);
          }

        /* Calculate the element number of bit zero in the first word
           of the set.  */
        if (GET_CODE (lo_r) == CONST_INT)
          rlow = GEN_INT (INTVAL (lo_r)
                          & ~ ((HOST_WIDE_INT) 1 << BITS_PER_UNIT));
        else
          rlow = expand_binop (index_mode, and_optab, lo_r,
                               GEN_INT (~((HOST_WIDE_INT) 1 << BITS_PER_UNIT)),
                               NULL_RTX, iunsignedp, OPTAB_LIB_WIDEN);

        diff = expand_binop (index_mode, sub_optab, index_val, rlow,
                             NULL_RTX, iunsignedp, OPTAB_LIB_WIDEN);

        quo = expand_divmod (0, TRUNC_DIV_EXPR, index_mode, diff,
                             GEN_INT (BITS_PER_UNIT), NULL_RTX, iunsignedp);
        rem = expand_divmod (1, TRUNC_MOD_EXPR, index_mode, index_val,
                             GEN_INT (BITS_PER_UNIT), NULL_RTX, iunsignedp);

        addr = memory_address (byte_mode,
                               expand_binop (index_mode, add_optab, diff,
                                             setaddr, NULL_RTX, iunsignedp,
                                             OPTAB_LIB_WIDEN));

        /* Extract the bit we want to examine */
        bit = expand_shift (RSHIFT_EXPR, byte_mode,
                            gen_rtx_MEM (byte_mode, addr),
                            make_tree (TREE_TYPE (index), rem),
                            NULL_RTX, 1);
        result = expand_binop (byte_mode, and_optab, bit, const1_rtx,
                               GET_MODE (target) == byte_mode ? target : 0,
                               1, OPTAB_LIB_WIDEN);

        if (result != target)
          convert_move (target, result, 1);

        /* Output the code to handle the out-of-range case.  */
        emit_jump (op0);
        emit_label (op1);
        emit_move_insn (target, const0_rtx);
        emit_label (op0);
        return target;
      }

    case WITH_CLEANUP_EXPR:
      if (RTL_EXPR_RTL (exp) == 0)
        {
          RTL_EXPR_RTL (exp)
            = expand_expr (TREE_OPERAND (exp, 0), target, tmode, ro_modifier);
          expand_decl_cleanup (NULL_TREE, TREE_OPERAND (exp, 2));

          /* That's it for this cleanup.  */
          TREE_OPERAND (exp, 2) = 0;
        }
      return RTL_EXPR_RTL (exp);

    case CLEANUP_POINT_EXPR:
      {
        /* Start a new binding layer that will keep track of all cleanup
           actions to be performed.  */
        expand_start_bindings (2);

        target_temp_slot_level = temp_slot_level;

        op0 = expand_expr (TREE_OPERAND (exp, 0), target, tmode, ro_modifier);
        /* If we're going to use this value, load it up now.  */
        if (! ignore)
          op0 = force_not_mem (op0);
        preserve_temp_slots (op0);
        expand_end_bindings (NULL_TREE, 0, 0);
      }
      return op0;

    case CALL_EXPR:
      /* Check for a built-in function.  */
      if (TREE_CODE (TREE_OPERAND (exp, 0)) == ADDR_EXPR
          && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0))
              == FUNCTION_DECL)
          && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)))
        return expand_builtin (exp, target, subtarget, tmode, ignore);

      /* If this call was expanded already by preexpand_calls,
         just return the result we got.  */
      if (CALL_EXPR_RTL (exp) != 0)
        return CALL_EXPR_RTL (exp);

      return expand_call (exp, target, ignore);

    case NON_LVALUE_EXPR:
    case NOP_EXPR:
    case CONVERT_EXPR:
    case REFERENCE_EXPR:
      if (TREE_OPERAND (exp, 0) == error_mark_node)
        return const0_rtx;

      if (TREE_CODE (type) == UNION_TYPE)
        {
          tree valtype = TREE_TYPE (TREE_OPERAND (exp, 0));

          /* If both input and output are BLKmode, this conversion
             isn't actually doing anything unless we need to make the
             alignment stricter.  */
          if (mode == BLKmode && TYPE_MODE (valtype) == BLKmode
              && (TYPE_ALIGN (type) <= TYPE_ALIGN (valtype)
                  || TYPE_ALIGN (type) >= BIGGEST_ALIGNMENT))
            return expand_expr (TREE_OPERAND (exp, 0), target, tmode,
                                modifier);

          if (target == 0)
            {
              if (mode != BLKmode)
                target = gen_reg_rtx (tmode != VOIDmode ? tmode : mode);
              else
                target = assign_temp (type, 0, 1, 1);
            }

          if (GET_CODE (target) == MEM)
            /* Store data into beginning of memory target.  */
            store_expr (TREE_OPERAND (exp, 0),
                        change_address (target, TYPE_MODE (valtype), 0), 0);

          else if (GET_CODE (target) == REG)
            /* Store this field into a union of the proper type.  */
            store_field (target,
                         MIN ((int_size_in_bytes (TREE_TYPE
                                                  (TREE_OPERAND (exp, 0)))
                               * BITS_PER_UNIT),
                              GET_MODE_BITSIZE (mode)),
                         0, TYPE_MODE (valtype), TREE_OPERAND (exp, 0),
                         VOIDmode, 0, BITS_PER_UNIT,
                         int_size_in_bytes (type), 0);
          else
            abort ();

          /* Return the entire union.  */
          return target;
        }

      if (mode == TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))))
        {
          op0 = expand_expr (TREE_OPERAND (exp, 0), target, VOIDmode,
                             ro_modifier);

          /* If the signedness of the conversion differs and OP0 is
             a promoted SUBREG, clear that indication since we now
             have to do the proper extension.  */
          if (TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0))) != unsignedp
              && GET_CODE (op0) == SUBREG)
            SUBREG_PROMOTED_VAR_P (op0) = 0;

          return op0;
        }

      op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, mode, 0);
      if (GET_MODE (op0) == mode)
        return op0;

      /* If OP0 is a constant, just convert it into the proper mode.  */
      if (CONSTANT_P (op0))
        return
          convert_modes (mode, TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))),
                         op0, TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0))));

      if (modifier == EXPAND_INITIALIZER)
        return gen_rtx_fmt_e (unsignedp ? ZERO_EXTEND : SIGN_EXTEND, mode, op0);

      if (target == 0)
        return
          convert_to_mode (mode, op0,
                           TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0))));
      else
        convert_move (target, op0,
                      TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0))));
      return target;

    case PLUS_EXPR:
      /* We come here from MINUS_EXPR when the second operand is a
         constant.  */
    plus_expr:
      this_optab = add_optab;

      /* If we are adding a constant, an RTL_EXPR that is sp, fp, or ap, and
         something else, make sure we add the register to the constant and
         then to the other thing.  This case can occur during strength
         reduction and doing it this way will produce better code if the
         frame pointer or argument pointer is eliminated.

         fold-const.c will ensure that the constant is always in the inner
         PLUS_EXPR, so the only case we need to do anything about is if
         sp, ap, or fp is our second argument, in which case we must swap
         the innermost first argument and our second argument.  */

      if (TREE_CODE (TREE_OPERAND (exp, 0)) == PLUS_EXPR
          && TREE_CODE (TREE_OPERAND (TREE_OPERAND (exp, 0), 1)) == INTEGER_CST
          && TREE_CODE (TREE_OPERAND (exp, 1)) == RTL_EXPR
          && (RTL_EXPR_RTL (TREE_OPERAND (exp, 1)) == frame_pointer_rtx
              || RTL_EXPR_RTL (TREE_OPERAND (exp, 1)) == stack_pointer_rtx
              || RTL_EXPR_RTL (TREE_OPERAND (exp, 1)) == arg_pointer_rtx))
        {
          tree t = TREE_OPERAND (exp, 1);

          TREE_OPERAND (exp, 1) = TREE_OPERAND (TREE_OPERAND (exp, 0), 0);
          TREE_OPERAND (TREE_OPERAND (exp, 0), 0) = t;
        }

      /* If the result is to be ptr_mode and we are adding an integer to
         something, we might be forming a constant.  So try to use
         plus_constant.  If it produces a sum and we can't accept it,
         use force_operand.  This allows P = &ARR[const] to generate
         efficient code on machines where a SYMBOL_REF is not a valid
         address.

         If this is an EXPAND_SUM call, always return the sum.  */
      if (modifier == EXPAND_SUM || modifier == EXPAND_INITIALIZER
          || mode == ptr_mode)
        {
          if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST
              && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
              && TREE_CONSTANT (TREE_OPERAND (exp, 1)))
            {
              rtx constant_part;

              op1 = expand_expr (TREE_OPERAND (exp, 1), subtarget, VOIDmode,
                                 EXPAND_SUM);
              /* Use immed_double_const to ensure that the constant is
                 truncated according to the mode of OP1, then sign extended
                 to a HOST_WIDE_INT.  Using the constant directly can result
                 in non-canonical RTL in a 64x32 cross compile.  */
              constant_part
                = immed_double_const (TREE_INT_CST_LOW (TREE_OPERAND (exp, 0)),
                                      (HOST_WIDE_INT) 0,
                                      TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 1))));
              op1 = plus_constant (op1, INTVAL (constant_part));
              if (modifier != EXPAND_SUM && modifier != EXPAND_INITIALIZER)
                op1 = force_operand (op1, target);
              return op1;
            }

          else if (TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
                   && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_INT
                   && TREE_CONSTANT (TREE_OPERAND (exp, 0)))
            {
              rtx constant_part;

              op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode,
                                 EXPAND_SUM);
              if (! CONSTANT_P (op0))
                {
                  op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX,
                                     VOIDmode, modifier);
                  /* Don't go to both_summands if modifier
                     says it's not right to return a PLUS.  */
                  if (modifier != EXPAND_SUM && modifier != EXPAND_INITIALIZER)
                    goto binop2;
                  goto both_summands;
                }
              /* Use immed_double_const to ensure that the constant is
                 truncated according to the mode of OP1, then sign extended
                 to a HOST_WIDE_INT.  Using the constant directly can result
                 in non-canonical RTL in a 64x32 cross compile.  */
              constant_part
                = immed_double_const (TREE_INT_CST_LOW (TREE_OPERAND (exp, 1)),
                                      (HOST_WIDE_INT) 0,
                                      TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))));
              op0 = plus_constant (op0, INTVAL (constant_part));
              if (modifier != EXPAND_SUM && modifier != EXPAND_INITIALIZER)
                op0 = force_operand (op0, target);
              return op0;
            }
        }

      /* No sense saving up arithmetic to be done
         if it's all in the wrong mode to form part of an address.
         And force_operand won't know whether to sign-extend or
         zero-extend.  */
      if ((modifier != EXPAND_SUM && modifier != EXPAND_INITIALIZER)
          || mode != ptr_mode)
        goto binop;

      preexpand_calls (exp);
      if (! safe_from_p (subtarget, TREE_OPERAND (exp, 1), 1))
        subtarget = 0;

      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, ro_modifier);
      op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, ro_modifier);

    both_summands:
      /* Make sure any term that's a sum with a constant comes last.  */
      if (GET_CODE (op0) == PLUS
          && CONSTANT_P (XEXP (op0, 1)))
        {
          temp = op0;
          op0 = op1;
          op1 = temp;
        }
      /* If adding to a sum including a constant,
         associate it to put the constant outside.  */
      if (GET_CODE (op1) == PLUS
          && CONSTANT_P (XEXP (op1, 1)))
        {
          rtx constant_term = const0_rtx;

          temp = simplify_binary_operation (PLUS, mode, XEXP (op1, 0), op0);
          if (temp != 0)
            op0 = temp;
          /* Ensure that MULT comes first if there is one.  */
          else if (GET_CODE (op0) == MULT)
            op0 = gen_rtx_PLUS (mode, op0, XEXP (op1, 0));
          else
            op0 = gen_rtx_PLUS (mode, XEXP (op1, 0), op0);

          /* Let's also eliminate constants from op0 if possible.  */
          op0 = eliminate_constant_term (op0, &constant_term);

          /* CONSTANT_TERM and XEXP (op1, 1) are known to be constant, so
             their sum should be a constant.  Form it into OP1, since the 
             result we want will then be OP0 + OP1.  */

          temp = simplify_binary_operation (PLUS, mode, constant_term,
                                            XEXP (op1, 1));
          if (temp != 0)
            op1 = temp;
          else
            op1 = gen_rtx_PLUS (mode, constant_term, XEXP (op1, 1));
        }

      /* Put a constant term last and put a multiplication first.  */
      if (CONSTANT_P (op0) || GET_CODE (op1) == MULT)
        temp = op1, op1 = op0, op0 = temp;

      temp = simplify_binary_operation (PLUS, mode, op0, op1);
      return temp ? temp : gen_rtx_PLUS (mode, op0, op1);

    case MINUS_EXPR:
      /* For initializers, we are allowed to return a MINUS of two
         symbolic constants.  Here we handle all cases when both operands
         are constant.  */
      /* Handle difference of two symbolic constants,
         for the sake of an initializer.  */
      if ((modifier == EXPAND_SUM || modifier == EXPAND_INITIALIZER)
          && really_constant_p (TREE_OPERAND (exp, 0))
          && really_constant_p (TREE_OPERAND (exp, 1)))
        {
          rtx op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX,
                                 VOIDmode, ro_modifier);
          rtx op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX,
                                 VOIDmode, ro_modifier);

          /* If the last operand is a CONST_INT, use plus_constant of
             the negated constant.  Else make the MINUS.  */
          if (GET_CODE (op1) == CONST_INT)
            return plus_constant (op0, - INTVAL (op1));
          else
            return gen_rtx_MINUS (mode, op0, op1);
        }
      /* Convert A - const to A + (-const).  */
      if (TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST)
        {
          tree negated = fold (build1 (NEGATE_EXPR, type,
                                       TREE_OPERAND (exp, 1)));

          if (TREE_UNSIGNED (type) || TREE_OVERFLOW (negated))
            /* If we can't negate the constant in TYPE, leave it alone and
               expand_binop will negate it for us.  We used to try to do it
               here in the signed version of TYPE, but that doesn't work
               on POINTER_TYPEs.  */;
          else
            {
              exp = build (PLUS_EXPR, type, TREE_OPERAND (exp, 0), negated);
              goto plus_expr;
            }
        }
      this_optab = sub_optab;
      goto binop;

    case MULT_EXPR:
      preexpand_calls (exp);
      /* If first operand is constant, swap them.
         Thus the following special case checks need only
         check the second operand.  */
      if (TREE_CODE (TREE_OPERAND (exp, 0)) == INTEGER_CST)
        {
          register tree t1 = TREE_OPERAND (exp, 0);
          TREE_OPERAND (exp, 0) = TREE_OPERAND (exp, 1);
          TREE_OPERAND (exp, 1) = t1;
        }

      /* Attempt to return something suitable for generating an
         indexed address, for machines that support that.  */

      if (modifier == EXPAND_SUM && mode == ptr_mode
          && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
          && GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT)
        {
          op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode,
                             EXPAND_SUM);

          /* Apply distributive law if OP0 is x+c.  */
          if (GET_CODE (op0) == PLUS
              && GET_CODE (XEXP (op0, 1)) == CONST_INT)
            return
              gen_rtx_PLUS
                (mode,
                 gen_rtx_MULT
                 (mode, XEXP (op0, 0),
                  GEN_INT (TREE_INT_CST_LOW (TREE_OPERAND (exp, 1)))),
                 GEN_INT (TREE_INT_CST_LOW (TREE_OPERAND (exp, 1))
                          * INTVAL (XEXP (op0, 1))));

          if (GET_CODE (op0) != REG)
            op0 = force_operand (op0, NULL_RTX);
          if (GET_CODE (op0) != REG)
            op0 = copy_to_mode_reg (mode, op0);

          return
            gen_rtx_MULT (mode, op0,
                          GEN_INT (TREE_INT_CST_LOW (TREE_OPERAND (exp, 1))));
        }

      if (! safe_from_p (subtarget, TREE_OPERAND (exp, 1), 1))
        subtarget = 0;

      /* Check for multiplying things that have been extended
         from a narrower type.  If this machine supports multiplying
         in that narrower type with a result in the desired type,
         do it that way, and avoid the explicit type-conversion.  */
      if (TREE_CODE (TREE_OPERAND (exp, 0)) == NOP_EXPR
          && TREE_CODE (type) == INTEGER_TYPE
          && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)))
              < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0))))
          && ((TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
               && int_fits_type_p (TREE_OPERAND (exp, 1),
                                   TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)))
               /* Don't use a widening multiply if a shift will do.  */
               && ((GET_MODE_BITSIZE (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 1))))
                    > HOST_BITS_PER_WIDE_INT)
                   || exact_log2 (TREE_INT_CST_LOW (TREE_OPERAND (exp, 1))) < 0))
              ||
              (TREE_CODE (TREE_OPERAND (exp, 1)) == NOP_EXPR
               && (TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 1), 0)))
                   ==
                   TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0))))
               /* If both operands are extended, they must either both
                  be zero-extended or both be sign-extended.  */
               && (TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 1), 0)))
                   ==
                   TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)))))))
        {
          enum machine_mode innermode
            = TYPE_MODE (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)));
          optab other_optab = (TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)))
                        ? smul_widen_optab : umul_widen_optab);
          this_optab = (TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0)))
                        ? umul_widen_optab : smul_widen_optab);
          if (mode == GET_MODE_WIDER_MODE (innermode))
            {
              if (this_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing)
                {
                  op0 = expand_expr (TREE_OPERAND (TREE_OPERAND (exp, 0), 0),
                                     NULL_RTX, VOIDmode, 0);
                  if (TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST)
                    op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX,
                                       VOIDmode, 0);
                  else
                    op1 = expand_expr (TREE_OPERAND (TREE_OPERAND (exp, 1), 0),
                                       NULL_RTX, VOIDmode, 0);
                  goto binop2;
                }
              else if (other_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing
                       && innermode == word_mode)
                {
                  rtx htem;
                  op0 = expand_expr (TREE_OPERAND (TREE_OPERAND (exp, 0), 0),
                                     NULL_RTX, VOIDmode, 0);
                  if (TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST)
                    op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX,
                                       VOIDmode, 0);
                  else
                    op1 = expand_expr (TREE_OPERAND (TREE_OPERAND (exp, 1), 0),
                                       NULL_RTX, VOIDmode, 0);
                  temp = expand_binop (mode, other_optab, op0, op1, target,
                                       unsignedp, OPTAB_LIB_WIDEN);
                  htem = expand_mult_highpart_adjust (innermode,
                                                      gen_highpart (innermode, temp),
                                                      op0, op1,
                                                      gen_highpart (innermode, temp),
                                                      unsignedp);
                  emit_move_insn (gen_highpart (innermode, temp), htem);
                  return temp;
                }
            }
        }
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
      return expand_mult (mode, op0, op1, target, unsignedp);

    case TRUNC_DIV_EXPR:
    case FLOOR_DIV_EXPR:
    case CEIL_DIV_EXPR:
    case ROUND_DIV_EXPR:
    case EXACT_DIV_EXPR:
      preexpand_calls (exp);
      if (! safe_from_p (subtarget, TREE_OPERAND (exp, 1), 1))
        subtarget = 0;
      /* Possible optimization: compute the dividend with EXPAND_SUM
         then if the divisor is constant can optimize the case
         where some terms of the dividend have coeffs divisible by it.  */
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
      return expand_divmod (0, code, mode, op0, op1, target, unsignedp);

    case RDIV_EXPR:
      this_optab = flodiv_optab;
      goto binop;

    case TRUNC_MOD_EXPR:
    case FLOOR_MOD_EXPR:
    case CEIL_MOD_EXPR:
    case ROUND_MOD_EXPR:
      preexpand_calls (exp);
      if (! safe_from_p (subtarget, TREE_OPERAND (exp, 1), 1))
        subtarget = 0;
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
      return expand_divmod (1, code, mode, op0, op1, target, unsignedp);

    case FIX_ROUND_EXPR:
    case FIX_FLOOR_EXPR:
    case FIX_CEIL_EXPR:
      abort ();                 /* Not used for C.  */

    case FIX_TRUNC_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
      if (target == 0)
        target = gen_reg_rtx (mode);
      expand_fix (target, op0, unsignedp);
      return target;

    case FLOAT_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
      if (target == 0)
        target = gen_reg_rtx (mode);
      /* expand_float can't figure out what to do if FROM has VOIDmode.
         So give it the correct mode.  With -O, cse will optimize this.  */
      if (GET_MODE (op0) == VOIDmode)
        op0 = copy_to_mode_reg (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))),
                                op0);
      expand_float (target, op0,
                    TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0))));
      return target;

    case NEGATE_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      temp = expand_unop (mode, neg_optab, op0, target, 0);
      if (temp == 0)
        abort ();
      return temp;

    case ABS_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);

      /* Handle complex values specially.  */
      if (GET_MODE_CLASS (mode) == MODE_COMPLEX_INT
          || GET_MODE_CLASS (mode) == MODE_COMPLEX_FLOAT)
        return expand_complex_abs (mode, op0, target, unsignedp);

      /* Unsigned abs is simply the operand.  Testing here means we don't
         risk generating incorrect code below.  */
      if (TREE_UNSIGNED (type))
        return op0;

      return expand_abs (mode, op0, target,
                         safe_from_p (target, TREE_OPERAND (exp, 0), 1));

    case MAX_EXPR:
    case MIN_EXPR:
      target = original_target;
      if (target == 0 || ! safe_from_p (target, TREE_OPERAND (exp, 1), 1)
          || (GET_CODE (target) == MEM && MEM_VOLATILE_P (target))
          || GET_MODE (target) != mode
          || (GET_CODE (target) == REG
              && REGNO (target) < FIRST_PSEUDO_REGISTER))
        target = gen_reg_rtx (mode);
      op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
      op0 = expand_expr (TREE_OPERAND (exp, 0), target, VOIDmode, 0);

      /* First try to do it with a special MIN or MAX instruction.
         If that does not win, use a conditional jump to select the proper
         value.  */
      this_optab = (TREE_UNSIGNED (type)
                    ? (code == MIN_EXPR ? umin_optab : umax_optab)
                    : (code == MIN_EXPR ? smin_optab : smax_optab));

      temp = expand_binop (mode, this_optab, op0, op1, target, unsignedp,
                           OPTAB_WIDEN);
      if (temp != 0)
        return temp;

      /* At this point, a MEM target is no longer useful; we will get better
         code without it.  */
         
      if (GET_CODE (target) == MEM)
        target = gen_reg_rtx (mode);

      if (target != op0)
        emit_move_insn (target, op0);

      op0 = gen_label_rtx ();

      /* If this mode is an integer too wide to compare properly,
         compare word by word.  Rely on cse to optimize constant cases.  */
      if (GET_MODE_CLASS (mode) == MODE_INT
          && ! can_compare_p (GE, mode, ccp_jump))
        {
          if (code == MAX_EXPR)
            do_jump_by_parts_greater_rtx (mode, TREE_UNSIGNED (type),
                                          target, op1, NULL_RTX, op0);
          else
            do_jump_by_parts_greater_rtx (mode, TREE_UNSIGNED (type),
                                          op1, target, NULL_RTX, op0);
        }
      else
        {
          int unsignedp = TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 1)));
          do_compare_rtx_and_jump (target, op1, code == MAX_EXPR ? GE : LE,
                                   unsignedp, mode, NULL_RTX, 0, NULL_RTX,
                                   op0);
        }
      emit_move_insn (target, op1);
      emit_label (op0);
      return target;

    case BIT_NOT_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      temp = expand_unop (mode, one_cmpl_optab, op0, target, 1);
      if (temp == 0)
        abort ();
      return temp;

    case FFS_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      temp = expand_unop (mode, ffs_optab, op0, target, 1);
      if (temp == 0)
        abort ();
      return temp;

      /* ??? Can optimize bitwise operations with one arg constant.
         Can optimize (a bitwise1 n) bitwise2 (a bitwise3 b)
         and (a bitwise1 b) bitwise2 b (etc)
         but that is probably not worth while.  */

      /* BIT_AND_EXPR is for bitwise anding.  TRUTH_AND_EXPR is for anding two
         boolean values when we want in all cases to compute both of them.  In
         general it is fastest to do TRUTH_AND_EXPR by computing both operands
         as actual zero-or-1 values and then bitwise anding.  In cases where
         there cannot be any side effects, better code would be made by
         treating TRUTH_AND_EXPR like TRUTH_ANDIF_EXPR; but the question is
         how to recognize those cases.  */

    case TRUTH_AND_EXPR:
    case BIT_AND_EXPR:
      this_optab = and_optab;
      goto binop;

    case TRUTH_OR_EXPR:
    case BIT_IOR_EXPR:
      this_optab = ior_optab;
      goto binop;

    case TRUTH_XOR_EXPR:
    case BIT_XOR_EXPR:
      this_optab = xor_optab;
      goto binop;

    case LSHIFT_EXPR:
    case RSHIFT_EXPR:
    case LROTATE_EXPR:
    case RROTATE_EXPR:
      preexpand_calls (exp);
      if (! safe_from_p (subtarget, TREE_OPERAND (exp, 1), 1))
        subtarget = 0;
      op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
      return expand_shift (code, mode, op0, TREE_OPERAND (exp, 1), target,
                           unsignedp);

      /* Could determine the answer when only additive constants differ.  Also,
         the addition of one can be handled by changing the condition.  */
    case LT_EXPR:
    case LE_EXPR:
    case GT_EXPR:
    case GE_EXPR:
    case EQ_EXPR:
    case NE_EXPR:
    case UNORDERED_EXPR:
    case ORDERED_EXPR:
    case UNLT_EXPR:
    case UNLE_EXPR:
    case UNGT_EXPR:
    case UNGE_EXPR:
    case UNEQ_EXPR:
      preexpand_calls (exp);
      temp = do_store_flag (exp, target, tmode != VOIDmode ? tmode : mode, 0);
      if (temp != 0)
        return temp;

      /* For foo != 0, load foo, and if it is nonzero load 1 instead.  */
      if (code == NE_EXPR && integer_zerop (TREE_OPERAND (exp, 1))
          && original_target
          && GET_CODE (original_target) == REG
          && (GET_MODE (original_target)
              == TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)))))
        {
          temp = expand_expr (TREE_OPERAND (exp, 0), original_target,
                              VOIDmode, 0);

          if (temp != original_target)
            temp = copy_to_reg (temp);

          op1 = gen_label_rtx ();
          emit_cmp_and_jump_insns (temp, const0_rtx, EQ, NULL_RTX,
                                   GET_MODE (temp), unsignedp, 0, op1);
          emit_move_insn (temp, const1_rtx);
          emit_label (op1);
          return temp;
        }

      /* If no set-flag instruction, must generate a conditional
         store into a temporary variable.  Drop through
         and handle this like && and ||.  */

    case TRUTH_ANDIF_EXPR:
    case TRUTH_ORIF_EXPR:
      if (! ignore
          && (target == 0 || ! safe_from_p (target, exp, 1)
              /* Make sure we don't have a hard reg (such as function's return
                 value) live across basic blocks, if not optimizing.  */
              || (!optimize && GET_CODE (target) == REG
                  && REGNO (target) < FIRST_PSEUDO_REGISTER)))
        target = gen_reg_rtx (tmode != VOIDmode ? tmode : mode);

      if (target)
        emit_clr_insn (target);

      op1 = gen_label_rtx ();
      jumpifnot (exp, op1);

      if (target)
        emit_0_to_1_insn (target);

      emit_label (op1);
      return ignore ? const0_rtx : target;

    case TRUTH_NOT_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), target, VOIDmode, 0);
      /* The parser is careful to generate TRUTH_NOT_EXPR
         only with operands that are always zero or one.  */
      temp = expand_binop (mode, xor_optab, op0, const1_rtx,
                           target, 1, OPTAB_LIB_WIDEN);
      if (temp == 0)
        abort ();
      return temp;

    case COMPOUND_EXPR:
      expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
      emit_queue ();
      return expand_expr (TREE_OPERAND (exp, 1),
                          (ignore ? const0_rtx : target),
                          VOIDmode, 0);

    case COND_EXPR:
      /* If we would have a "singleton" (see below) were it not for a
         conversion in each arm, bring that conversion back out.  */
      if (TREE_CODE (TREE_OPERAND (exp, 1)) == NOP_EXPR
          && TREE_CODE (TREE_OPERAND (exp, 2)) == NOP_EXPR
          && (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 1), 0))
              == TREE_TYPE (TREE_OPERAND (TREE_OPERAND (exp, 2), 0))))
        {
          tree true = TREE_OPERAND (TREE_OPERAND (exp, 1), 0);
          tree false = TREE_OPERAND (TREE_OPERAND (exp, 2), 0);

          if ((TREE_CODE_CLASS (TREE_CODE (true)) == '2'
               && operand_equal_p (false, TREE_OPERAND (true, 0), 0))
              || (TREE_CODE_CLASS (TREE_CODE (false)) == '2'
                  && operand_equal_p (true, TREE_OPERAND (false, 0), 0))
              || (TREE_CODE_CLASS (TREE_CODE (true)) == '1'
                  && operand_equal_p (false, TREE_OPERAND (true, 0), 0))
              || (TREE_CODE_CLASS (TREE_CODE (false)) == '1'
                  && operand_equal_p (true, TREE_OPERAND (false, 0), 0)))
            return expand_expr (build1 (NOP_EXPR, type,
                                        build (COND_EXPR, TREE_TYPE (true),
                                               TREE_OPERAND (exp, 0),
                                               true, false)),
                                target, tmode, modifier);
        }

      {
        /* Note that COND_EXPRs whose type is a structure or union
           are required to be constructed to contain assignments of
           a temporary variable, so that we can evaluate them here
           for side effect only.  If type is void, we must do likewise.  */

        /* If an arm of the branch requires a cleanup,
           only that cleanup is performed.  */

        tree singleton = 0;
        tree binary_op = 0, unary_op = 0;

        /* If this is (A ? 1 : 0) and A is a condition, just evaluate it and
           convert it to our mode, if necessary.  */
        if (integer_onep (TREE_OPERAND (exp, 1))
            && integer_zerop (TREE_OPERAND (exp, 2))
            && TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 0))) == '<')
          {
            if (ignore)
              {
                expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode,
                             ro_modifier);
                return const0_rtx;
              }

            op0 = expand_expr (TREE_OPERAND (exp, 0), target, mode, ro_modifier);
            if (GET_MODE (op0) == mode)
              return op0;

            if (target == 0)
              target = gen_reg_rtx (mode);
            convert_move (target, op0, unsignedp);
            return target;
          }

        /* Check for X ? A + B : A.  If we have this, we can copy A to the
           output and conditionally add B.  Similarly for unary operations.
           Don't do this if X has side-effects because those side effects
           might affect A or B and the "?" operation is a sequence point in
           ANSI.  (operand_equal_p tests for side effects.)  */

        if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 1))) == '2'
            && operand_equal_p (TREE_OPERAND (exp, 2),
                                TREE_OPERAND (TREE_OPERAND (exp, 1), 0), 0))
          singleton = TREE_OPERAND (exp, 2), binary_op = TREE_OPERAND (exp, 1);
        else if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 2))) == '2'
                 && operand_equal_p (TREE_OPERAND (exp, 1),
                                     TREE_OPERAND (TREE_OPERAND (exp, 2), 0), 0))
          singleton = TREE_OPERAND (exp, 1), binary_op = TREE_OPERAND (exp, 2);
        else if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 1))) == '1'
                 && operand_equal_p (TREE_OPERAND (exp, 2),
                                     TREE_OPERAND (TREE_OPERAND (exp, 1), 0), 0))
          singleton = TREE_OPERAND (exp, 2), unary_op = TREE_OPERAND (exp, 1);
        else if (TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 2))) == '1'
                 && operand_equal_p (TREE_OPERAND (exp, 1),
                                     TREE_OPERAND (TREE_OPERAND (exp, 2), 0), 0))
          singleton = TREE_OPERAND (exp, 1), unary_op = TREE_OPERAND (exp, 2);

        /* If we are not to produce a result, we have no target.  Otherwise,
           if a target was specified use it; it will not be used as an
           intermediate target unless it is safe.  If no target, use a 
           temporary.  */

        if (ignore)
          temp = 0;
        else if (original_target
                 && (safe_from_p (original_target, TREE_OPERAND (exp, 0), 1)
                     || (singleton && GET_CODE (original_target) == REG
                         && REGNO (original_target) >= FIRST_PSEUDO_REGISTER
                         && original_target == var_rtx (singleton)))
                 && GET_MODE (original_target) == mode
#ifdef HAVE_conditional_move
                 && (! can_conditionally_move_p (mode)
                     || GET_CODE (original_target) == REG
                     || TREE_ADDRESSABLE (type))
#endif
                 && ! (GET_CODE (original_target) == MEM
                       && MEM_VOLATILE_P (original_target)))
          temp = original_target;
        else if (TREE_ADDRESSABLE (type))
          abort ();
        else
          temp = assign_temp (type, 0, 0, 1);

        /* If we had X ? A + C : A, with C a constant power of 2, and we can
           do the test of X as a store-flag operation, do this as
           A + ((X != 0) << log C).  Similarly for other simple binary
           operators.  Only do for C == 1 if BRANCH_COST is low.  */
        if (temp && singleton && binary_op
            && (TREE_CODE (binary_op) == PLUS_EXPR
                || TREE_CODE (binary_op) == MINUS_EXPR
                || TREE_CODE (binary_op) == BIT_IOR_EXPR
                || TREE_CODE (binary_op) == BIT_XOR_EXPR)
            && (BRANCH_COST >= 3 ? integer_pow2p (TREE_OPERAND (binary_op, 1))
                : integer_onep (TREE_OPERAND (binary_op, 1)))
            && TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 0))) == '<')
          {
            rtx result;
            optab boptab = (TREE_CODE (binary_op) == PLUS_EXPR ? add_optab
                            : TREE_CODE (binary_op) == MINUS_EXPR ? sub_optab
                            : TREE_CODE (binary_op) == BIT_IOR_EXPR ? ior_optab
                            : xor_optab);

            /* If we had X ? A : A + 1, do this as A + (X == 0).

               We have to invert the truth value here and then put it
               back later if do_store_flag fails.  We cannot simply copy
               TREE_OPERAND (exp, 0) to another variable and modify that
               because invert_truthvalue can modify the tree pointed to
               by its argument.  */
            if (singleton == TREE_OPERAND (exp, 1))
              TREE_OPERAND (exp, 0)
                = invert_truthvalue (TREE_OPERAND (exp, 0));

            result = do_store_flag (TREE_OPERAND (exp, 0),
                                    (safe_from_p (temp, singleton, 1)
                                     ? temp : NULL_RTX),
                                    mode, BRANCH_COST <= 1);

            if (result != 0 && ! integer_onep (TREE_OPERAND (binary_op, 1)))
              result = expand_shift (LSHIFT_EXPR, mode, result,
                                     build_int_2 (tree_log2
                                                  (TREE_OPERAND
                                                   (binary_op, 1)),
                                                  0),
                                     (safe_from_p (temp, singleton, 1)
                                      ? temp : NULL_RTX), 0);

            if (result)
              {
                op1 = expand_expr (singleton, NULL_RTX, VOIDmode, 0);
                return expand_binop (mode, boptab, op1, result, temp,
                                     unsignedp, OPTAB_LIB_WIDEN);
              }
            else if (singleton == TREE_OPERAND (exp, 1))
              TREE_OPERAND (exp, 0)
                = invert_truthvalue (TREE_OPERAND (exp, 0));
          }
            
        do_pending_stack_adjust ();
        NO_DEFER_POP;
        op0 = gen_label_rtx ();

        if (singleton && ! TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 0)))
          {
            if (temp != 0)
              {
                /* If the target conflicts with the other operand of the
                   binary op, we can't use it.  Also, we can't use the target
                   if it is a hard register, because evaluating the condition
                   might clobber it.  */
                if ((binary_op
                     && ! safe_from_p (temp, TREE_OPERAND (binary_op, 1), 1))
                    || (GET_CODE (temp) == REG
                        && REGNO (temp) < FIRST_PSEUDO_REGISTER))
                  temp = gen_reg_rtx (mode);
                store_expr (singleton, temp, 0);
              }
            else
              expand_expr (singleton,
                           ignore ? const0_rtx : NULL_RTX, VOIDmode, 0);
            if (singleton == TREE_OPERAND (exp, 1))
              jumpif (TREE_OPERAND (exp, 0), op0);
            else
              jumpifnot (TREE_OPERAND (exp, 0), op0);

            start_cleanup_deferral ();
            if (binary_op && temp == 0)
              /* Just touch the other operand.  */
              expand_expr (TREE_OPERAND (binary_op, 1),
                           ignore ? const0_rtx : NULL_RTX, VOIDmode, 0);
            else if (binary_op)
              store_expr (build (TREE_CODE (binary_op), type,
                                 make_tree (type, temp),
                                 TREE_OPERAND (binary_op, 1)),
                          temp, 0);
            else
              store_expr (build1 (TREE_CODE (unary_op), type,
                                  make_tree (type, temp)),
                          temp, 0);
            op1 = op0;
          }
        /* Check for A op 0 ? A : FOO and A op 0 ? FOO : A where OP is any
           comparison operator.  If we have one of these cases, set the
           output to A, branch on A (cse will merge these two references),
           then set the output to FOO.  */
        else if (temp
                 && TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 0))) == '<'
                 && integer_zerop (TREE_OPERAND (TREE_OPERAND (exp, 0), 1))
                 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (exp, 0), 0),
                                     TREE_OPERAND (exp, 1), 0)
                 && (! TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 0))
                     || TREE_CODE (TREE_OPERAND (exp, 1)) == SAVE_EXPR)
                 && safe_from_p (temp, TREE_OPERAND (exp, 2), 1))
          {
            if (GET_CODE (temp) == REG && REGNO (temp) < FIRST_PSEUDO_REGISTER)
              temp = gen_reg_rtx (mode);
            store_expr (TREE_OPERAND (exp, 1), temp, 0);
            jumpif (TREE_OPERAND (exp, 0), op0);

            start_cleanup_deferral ();
            store_expr (TREE_OPERAND (exp, 2), temp, 0);
            op1 = op0;
          }
        else if (temp
                 && TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, 0))) == '<'
                 && integer_zerop (TREE_OPERAND (TREE_OPERAND (exp, 0), 1))
                 && operand_equal_p (TREE_OPERAND (TREE_OPERAND (exp, 0), 0),
                                     TREE_OPERAND (exp, 2), 0)
                 && (! TREE_SIDE_EFFECTS (TREE_OPERAND (exp, 0))
                     || TREE_CODE (TREE_OPERAND (exp, 2)) == SAVE_EXPR)
                 && safe_from_p (temp, TREE_OPERAND (exp, 1), 1))
          {
            if (GET_CODE (temp) == REG && REGNO (temp) < FIRST_PSEUDO_REGISTER)
              temp = gen_reg_rtx (mode);
            store_expr (TREE_OPERAND (exp, 2), temp, 0);
            jumpifnot (TREE_OPERAND (exp, 0), op0);

            start_cleanup_deferral ();
            store_expr (TREE_OPERAND (exp, 1), temp, 0);
            op1 = op0;
          }
        else
          {
            op1 = gen_label_rtx ();
            jumpifnot (TREE_OPERAND (exp, 0), op0);

            start_cleanup_deferral ();
            
            /* One branch of the cond can be void, if it never returns. For
               example A ? throw : E  */
            if (temp != 0
                && TREE_TYPE (TREE_OPERAND (exp, 1)) != void_type_node)
              store_expr (TREE_OPERAND (exp, 1), temp, 0);
            else
              expand_expr (TREE_OPERAND (exp, 1),
                           ignore ? const0_rtx : NULL_RTX, VOIDmode, 0);
            end_cleanup_deferral ();
            emit_queue ();
            emit_jump_insn (gen_jump (op1));
            emit_barrier ();
            emit_label (op0);
            start_cleanup_deferral ();
            if (temp != 0
                && TREE_TYPE (TREE_OPERAND (exp, 2)) != void_type_node)
              store_expr (TREE_OPERAND (exp, 2), temp, 0);
            else
              expand_expr (TREE_OPERAND (exp, 2),
                           ignore ? const0_rtx : NULL_RTX, VOIDmode, 0);
          }

        end_cleanup_deferral ();

        emit_queue ();
        emit_label (op1);
        OK_DEFER_POP;

        return temp;
      }

    case TARGET_EXPR:
      {
        /* Something needs to be initialized, but we didn't know
           where that thing was when building the tree.  For example,
           it could be the return value of a function, or a parameter
           to a function which lays down in the stack, or a temporary
           variable which must be passed by reference.

           We guarantee that the expression will either be constructed
           or copied into our original target.  */

        tree slot = TREE_OPERAND (exp, 0);
        tree cleanups = NULL_TREE;
        tree exp1;

        if (TREE_CODE (slot) != VAR_DECL)
          abort ();

        if (! ignore)
          target = original_target;

        /* Set this here so that if we get a target that refers to a
           register variable that's already been used, put_reg_into_stack
           knows that it should fix up those uses.  */     
        TREE_USED (slot) = 1;

        if (target == 0)
          {
            if (DECL_RTL (slot) != 0)
              {
                target = DECL_RTL (slot);
                /* If we have already expanded the slot, so don't do
                   it again.  (mrs)  */
                if (TREE_OPERAND (exp, 1) == NULL_TREE)
                  return target;
              }
            else
              {
                target = assign_temp (type, 2, 0, 1);
                /* All temp slots at this level must not conflict.  */
                preserve_temp_slots (target);
                DECL_RTL (slot) = target;
                if (TREE_ADDRESSABLE (slot))
                  {
                    TREE_ADDRESSABLE (slot) = 0;
                    mark_addressable (slot);
                  }

                /* Since SLOT is not known to the called function
                   to belong to its stack frame, we must build an explicit
                   cleanup.  This case occurs when we must build up a reference
                   to pass the reference as an argument.  In this case,
                   it is very likely that such a reference need not be
                   built here.  */

                if (TREE_OPERAND (exp, 2) == 0)
                  TREE_OPERAND (exp, 2) = maybe_build_cleanup (slot);
                cleanups = TREE_OPERAND (exp, 2);
              }
          }
        else
          {
            /* This case does occur, when expanding a parameter which
               needs to be constructed on the stack.  The target
               is the actual stack address that we want to initialize.
               The function we call will perform the cleanup in this case.  */

            /* If we have already assigned it space, use that space,
               not target that we were passed in, as our target
               parameter is only a hint.  */
            if (DECL_RTL (slot) != 0)
              {
                target = DECL_RTL (slot);
                /* If we have already expanded the slot, so don't do
                   it again.  (mrs)  */
                if (TREE_OPERAND (exp, 1) == NULL_TREE)
                  return target;
              }
            else
              {
                DECL_RTL (slot) = target;
                /* If we must have an addressable slot, then make sure that
                   the RTL that we just stored in slot is OK.  */
                if (TREE_ADDRESSABLE (slot))
                  {
                    TREE_ADDRESSABLE (slot) = 0;
                    mark_addressable (slot);
                  }
              }
          }

        exp1 = TREE_OPERAND (exp, 3) = TREE_OPERAND (exp, 1);
        /* Mark it as expanded.  */
        TREE_OPERAND (exp, 1) = NULL_TREE;

        store_expr (exp1, target, 0);

        expand_decl_cleanup (NULL_TREE, cleanups);
        
        return target;
      }

    case INIT_EXPR:
      {
        tree lhs = TREE_OPERAND (exp, 0);
        tree rhs = TREE_OPERAND (exp, 1);
        tree noncopied_parts = 0;
        tree lhs_type = TREE_TYPE (lhs);

        temp = expand_assignment (lhs, rhs, ! ignore, original_target != 0);
        if (TYPE_NONCOPIED_PARTS (lhs_type) != 0 && !fixed_type_p (rhs))
          noncopied_parts = init_noncopied_parts (stabilize_reference (lhs),
                                                  TYPE_NONCOPIED_PARTS (lhs_type));
        while (noncopied_parts != 0)
          {
            expand_assignment (TREE_VALUE (noncopied_parts),
                               TREE_PURPOSE (noncopied_parts), 0, 0);
            noncopied_parts = TREE_CHAIN (noncopied_parts);
          }
        return temp;
      }

    case MODIFY_EXPR:
      {
        /* If lhs is complex, expand calls in rhs before computing it.
           That's so we don't compute a pointer and save it over a call.
           If lhs is simple, compute it first so we can give it as a
           target if the rhs is just a call.  This avoids an extra temp and copy
           and that prevents a partial-subsumption which makes bad code.
           Actually we could treat component_ref's of vars like vars.  */

        tree lhs = TREE_OPERAND (exp, 0);
        tree rhs = TREE_OPERAND (exp, 1);
        tree noncopied_parts = 0;
        tree lhs_type = TREE_TYPE (lhs);

        temp = 0;

        if (TREE_CODE (lhs) != VAR_DECL
            && TREE_CODE (lhs) != RESULT_DECL
            && TREE_CODE (lhs) != PARM_DECL
            && ! (TREE_CODE (lhs) == INDIRECT_REF
                  && TYPE_READONLY (TREE_TYPE (TREE_OPERAND (lhs, 0)))))
          preexpand_calls (exp);

        /* Check for |= or &= of a bitfield of size one into another bitfield
           of size 1.  In this case, (unless we need the result of the
           assignment) we can do this more efficiently with a
           test followed by an assignment, if necessary.

           ??? At this point, we can't get a BIT_FIELD_REF here.  But if
           things change so we do, this code should be enhanced to
           support it.  */
        if (ignore
            && TREE_CODE (lhs) == COMPONENT_REF
            && (TREE_CODE (rhs) == BIT_IOR_EXPR
                || TREE_CODE (rhs) == BIT_AND_EXPR)
            && TREE_OPERAND (rhs, 0) == lhs
            && TREE_CODE (TREE_OPERAND (rhs, 1)) == COMPONENT_REF
            && integer_onep (DECL_SIZE (TREE_OPERAND (lhs, 1)))
            && integer_onep (DECL_SIZE (TREE_OPERAND (TREE_OPERAND (rhs, 1), 1))))
          {
            rtx label = gen_label_rtx ();

            do_jump (TREE_OPERAND (rhs, 1),
                     TREE_CODE (rhs) == BIT_IOR_EXPR ? label : 0,
                     TREE_CODE (rhs) == BIT_AND_EXPR ? label : 0);
            expand_assignment (lhs, convert (TREE_TYPE (rhs),
                                             (TREE_CODE (rhs) == BIT_IOR_EXPR
                                              ? integer_one_node
                                              : integer_zero_node)),
                               0, 0);
            do_pending_stack_adjust ();
            emit_label (label);
            return const0_rtx;
          }

        if (TYPE_NONCOPIED_PARTS (lhs_type) != 0
            && ! (fixed_type_p (lhs) && fixed_type_p (rhs)))
          noncopied_parts = save_noncopied_parts (stabilize_reference (lhs),
                                                  TYPE_NONCOPIED_PARTS (lhs_type));

        temp = expand_assignment (lhs, rhs, ! ignore, original_target != 0);
        while (noncopied_parts != 0)
          {
            expand_assignment (TREE_PURPOSE (noncopied_parts),
                               TREE_VALUE (noncopied_parts), 0, 0);
            noncopied_parts = TREE_CHAIN (noncopied_parts);
          }
        return temp;
      }

    case RETURN_EXPR:
      if (!TREE_OPERAND (exp, 0))
        expand_null_return ();
      else
        expand_return (TREE_OPERAND (exp, 0));
      return const0_rtx;

    case PREINCREMENT_EXPR:
    case PREDECREMENT_EXPR:
      return expand_increment (exp, 0, ignore);

    case POSTINCREMENT_EXPR:
    case POSTDECREMENT_EXPR:
      /* Faster to treat as pre-increment if result is not used.  */
      return expand_increment (exp, ! ignore, ignore);

    case ADDR_EXPR:
      /* If nonzero, TEMP will be set to the address of something that might
         be a MEM corresponding to a stack slot.  */
      temp = 0;

      /* Are we taking the address of a nested function?  */
      if (TREE_CODE (TREE_OPERAND (exp, 0)) == FUNCTION_DECL
          && decl_function_context (TREE_OPERAND (exp, 0)) != 0
          && ! DECL_NO_STATIC_CHAIN (TREE_OPERAND (exp, 0))
          && ! TREE_STATIC (exp))
        {
          op0 = trampoline_address (TREE_OPERAND (exp, 0));
          op0 = force_operand (op0, target);
        }
      /* If we are taking the address of something erroneous, just
         return a zero.  */
      else if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
        return const0_rtx;
      else
        {
          /* We make sure to pass const0_rtx down if we came in with
             ignore set, to avoid doing the cleanups twice for something.  */
          op0 = expand_expr (TREE_OPERAND (exp, 0),
                             ignore ? const0_rtx : NULL_RTX, VOIDmode,
                             (modifier == EXPAND_INITIALIZER
                              ? modifier : EXPAND_CONST_ADDRESS));

          /* If we are going to ignore the result, OP0 will have been set
             to const0_rtx, so just return it.  Don't get confused and
             think we are taking the address of the constant.  */
          if (ignore)
            return op0;

          op0 = protect_from_queue (op0, 0);

          /* We would like the object in memory.  If it is a constant, we can
             have it be statically allocated into memory.  For a non-constant,
             we need to allocate some memory and store the value into it.  */

          if (CONSTANT_P (op0))
            op0 = force_const_mem (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))),
                                   op0);
          else if (GET_CODE (op0) == MEM)
            {
              mark_temp_addr_taken (op0);
              temp = XEXP (op0, 0);
            }

          else if (GET_CODE (op0) == REG || GET_CODE (op0) == SUBREG
                   || GET_CODE (op0) == CONCAT || GET_CODE (op0) == ADDRESSOF)
            {
              /* If this object is in a register, it must be not
                 be BLKmode.  */
              tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));
              rtx memloc = assign_temp (inner_type, 1, 1, 1);

              mark_temp_addr_taken (memloc);
              emit_move_insn (memloc, op0);
              op0 = memloc;
            }

          if (GET_CODE (op0) != MEM)
            abort ();
  
          if (modifier == EXPAND_SUM || modifier == EXPAND_INITIALIZER)
            {
              temp = XEXP (op0, 0);
#ifdef POINTERS_EXTEND_UNSIGNED
              if (GET_MODE (temp) == Pmode && GET_MODE (temp) != mode
                  && mode == ptr_mode)
                temp = convert_memory_address (ptr_mode, temp);
#endif
              return temp;
            }

          op0 = force_operand (XEXP (op0, 0), target);
        }

      if (flag_force_addr && GET_CODE (op0) != REG)
        op0 = force_reg (Pmode, op0);

      if (GET_CODE (op0) == REG
          && ! REG_USERVAR_P (op0))
        mark_reg_pointer (op0, TYPE_ALIGN (TREE_TYPE (type)));

      /* If we might have had a temp slot, add an equivalent address
         for it.  */
      if (temp != 0)
        update_temp_slot_address (temp, op0);

#ifdef POINTERS_EXTEND_UNSIGNED
      if (GET_MODE (op0) == Pmode && GET_MODE (op0) != mode
          && mode == ptr_mode)
        op0 = convert_memory_address (ptr_mode, op0);
#endif

      return op0;

    case ENTRY_VALUE_EXPR:
      abort ();

    /* COMPLEX type for Extended Pascal & Fortran  */
    case COMPLEX_EXPR:
      {
        enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_TYPE (exp)));
        rtx insns;

        /* Get the rtx code of the operands.  */
        op0 = expand_expr (TREE_OPERAND (exp, 0), 0, VOIDmode, 0);
        op1 = expand_expr (TREE_OPERAND (exp, 1), 0, VOIDmode, 0);

        if (! target)
          target = gen_reg_rtx (TYPE_MODE (TREE_TYPE (exp)));

        start_sequence ();

        /* Move the real (op0) and imaginary (op1) parts to their location.  */
        emit_move_insn (gen_realpart (mode, target), op0);
        emit_move_insn (gen_imagpart (mode, target), op1);

        insns = get_insns ();
        end_sequence ();

        /* Complex construction should appear as a single unit.  */
        /* If TARGET is a CONCAT, we got insns like RD = RS, ID = IS,
           each with a separate pseudo as destination.
           It's not correct for flow to treat them as a unit.  */
        if (GET_CODE (target) != CONCAT)
          emit_no_conflict_block (insns, target, op0, op1, NULL_RTX);
        else
          emit_insns (insns);

        return target;
      }

    case REALPART_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), 0, VOIDmode, 0);
      return gen_realpart (mode, op0);
      
    case IMAGPART_EXPR:
      op0 = expand_expr (TREE_OPERAND (exp, 0), 0, VOIDmode, 0);
      return gen_imagpart (mode, op0);

    case CONJ_EXPR:
      {
        enum machine_mode partmode = TYPE_MODE (TREE_TYPE (TREE_TYPE (exp)));
        rtx imag_t;
        rtx insns;
        
        op0  = expand_expr (TREE_OPERAND (exp, 0), 0, VOIDmode, 0);

        if (! target)
          target = gen_reg_rtx (mode);
                                                                    
        start_sequence ();

        /* Store the realpart and the negated imagpart to target.  */
        emit_move_insn (gen_realpart (partmode, target),
                        gen_realpart (partmode, op0));

        imag_t = gen_imagpart (partmode, target);
        temp = expand_unop (partmode, neg_optab,
                               gen_imagpart (partmode, op0), imag_t, 0);
        if (temp != imag_t)
          emit_move_insn (imag_t, temp);

        insns = get_insns ();
        end_sequence ();

        /* Conjugate should appear as a single unit 
           If TARGET is a CONCAT, we got insns like RD = RS, ID = - IS,
           each with a separate pseudo as destination.
           It's not correct for flow to treat them as a unit.  */
        if (GET_CODE (target) != CONCAT)
          emit_no_conflict_block (insns, target, op0, NULL_RTX, NULL_RTX);
        else
          emit_insns (insns);

        return target;
      }

    case TRY_CATCH_EXPR:
      {
        tree handler = TREE_OPERAND (exp, 1);

        expand_eh_region_start ();

        op0 = expand_expr (TREE_OPERAND (exp, 0), 0, VOIDmode, 0);

        expand_eh_region_end (handler);

        return op0;
      }

    case TRY_FINALLY_EXPR:
      {
        tree try_block = TREE_OPERAND (exp, 0);
        tree finally_block = TREE_OPERAND (exp, 1);
        rtx finally_label = gen_label_rtx ();
        rtx done_label = gen_label_rtx ();
        rtx return_link = gen_reg_rtx (Pmode);
        tree cleanup = build (GOTO_SUBROUTINE_EXPR, void_type_node,
                              (tree) finally_label, (tree) return_link);
        TREE_SIDE_EFFECTS (cleanup) = 1;

        /* Start a new binding layer that will keep track of all cleanup
           actions to be performed.  */
        expand_start_bindings (2);

        target_temp_slot_level = temp_slot_level;

        expand_decl_cleanup (NULL_TREE, cleanup);
        op0 = expand_expr (try_block, target, tmode, modifier);

        preserve_temp_slots (op0);
        expand_end_bindings (NULL_TREE, 0, 0);
        emit_jump (done_label);
        emit_label (finally_label);
        expand_expr (finally_block, const0_rtx, VOIDmode, 0);
        emit_indirect_jump (return_link);
        emit_label (done_label);
        return op0;
      }

      case GOTO_SUBROUTINE_EXPR:
      {
        rtx subr = (rtx) TREE_OPERAND (exp, 0);
        rtx return_link = *(rtx *) &TREE_OPERAND (exp, 1);
        rtx return_address = gen_label_rtx ();
        emit_move_insn (return_link, gen_rtx_LABEL_REF (Pmode, return_address));
        emit_jump (subr);
        emit_label (return_address);
        return const0_rtx;
      }

    case POPDCC_EXPR:
      {
        rtx dcc = get_dynamic_cleanup_chain ();
        emit_move_insn (dcc, validize_mem (gen_rtx_MEM (Pmode, dcc)));
        return const0_rtx;
      }

    case POPDHC_EXPR:
      {
        rtx dhc = get_dynamic_handler_chain ();
        emit_move_insn (dhc, validize_mem (gen_rtx_MEM (Pmode, dhc)));
        return const0_rtx;
      }

    case VA_ARG_EXPR:
      return expand_builtin_va_arg (TREE_OPERAND (exp, 0), type);

    default:
      return (*lang_expand_expr) (exp, original_target, tmode, modifier);
    }

  /* Here to do an ordinary binary operator, generating an instruction
     from the optab already placed in `this_optab'.  */
 binop:
  preexpand_calls (exp);
  if (! safe_from_p (subtarget, TREE_OPERAND (exp, 1), 1))
    subtarget = 0;
  op0 = expand_expr (TREE_OPERAND (exp, 0), subtarget, VOIDmode, 0);
  op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
 binop2:
  temp = expand_binop (mode, this_optab, op0, op1, target,
                       unsignedp, OPTAB_LIB_WIDEN);
  if (temp == 0)
    abort ();
  return temp;
}
\f
/* Similar to expand_expr, except that we don't specify a target, target
   mode, or modifier and we return the alignment of the inner type.  This is
   used in cases where it is not necessary to align the result to the
   alignment of its type as long as we know the alignment of the result, for
   example for comparisons of BLKmode values.  */

static rtx
expand_expr_unaligned (exp, palign)
     register tree exp;
     unsigned int *palign;
{
  register rtx op0;
  tree type = TREE_TYPE (exp);
  register enum machine_mode mode = TYPE_MODE (type);

  /* Default the alignment we return to that of the type.  */
  *palign = TYPE_ALIGN (type);

  /* The only cases in which we do anything special is if the resulting mode
     is BLKmode.  */
  if (mode != BLKmode)
    return expand_expr (exp, NULL_RTX, VOIDmode, EXPAND_NORMAL);

  switch (TREE_CODE (exp))
    {
    case CONVERT_EXPR:
    case NOP_EXPR:
    case NON_LVALUE_EXPR:
      /* Conversions between BLKmode values don't change the underlying
         alignment or value.  */
      if (TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == BLKmode)
        return expand_expr_unaligned (TREE_OPERAND (exp, 0), palign);
      break;

    case ARRAY_REF:
      /* Much of the code for this case is copied directly from expand_expr.
         We need to duplicate it here because we will do something different
         in the fall-through case, so we need to handle the same exceptions
         it does.  */
      {
        tree array = TREE_OPERAND (exp, 0);
        tree domain = TYPE_DOMAIN (TREE_TYPE (array));
        tree low_bound = domain ? TYPE_MIN_VALUE (domain) : integer_zero_node;
        tree index = convert (sizetype, TREE_OPERAND (exp, 1));
        HOST_WIDE_INT i;

        if (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) != ARRAY_TYPE)
          abort ();

        /* Optimize the special-case of a zero lower bound.

           We convert the low_bound to sizetype to avoid some problems
           with constant folding.  (E.g. suppose the lower bound is 1,
           and its mode is QI.  Without the conversion,  (ARRAY
           +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
           +INDEX), which becomes (ARRAY+255+INDEX).  Oops!)  */

        if (! integer_zerop (low_bound))
          index = size_diffop (index, convert (sizetype, low_bound));

        /* If this is a constant index into a constant array,
           just get the value from the array.  Handle both the cases when
           we have an explicit constructor and when our operand is a variable
           that was declared const.  */

        if (TREE_CODE (array) == CONSTRUCTOR && ! TREE_SIDE_EFFECTS (array)
            && 0 > compare_tree_int (index, 
                                     list_length (CONSTRUCTOR_ELTS
                                                  (TREE_OPERAND (exp, 0)))))
          {
            tree elem;

            for (elem = CONSTRUCTOR_ELTS (TREE_OPERAND (exp, 0)),
                 i = TREE_INT_CST_LOW (index);
                 elem != 0 && i != 0; i--, elem = TREE_CHAIN (elem))
              ;

            if (elem)
              return expand_expr_unaligned (fold (TREE_VALUE (elem)), palign);
          }
          
        else if (optimize >= 1
                 && TREE_READONLY (array) && ! TREE_SIDE_EFFECTS (array)
                 && TREE_CODE (array) == VAR_DECL && DECL_INITIAL (array)
                 && TREE_CODE (DECL_INITIAL (array)) != ERROR_MARK)
          {
            if (TREE_CODE (index) == INTEGER_CST)
              {
                tree init = DECL_INITIAL (array);

                if (TREE_CODE (init) == CONSTRUCTOR)
                  {
                    tree elem;

                    for (elem = CONSTRUCTOR_ELTS (init);
                         ! tree_int_cst_equal (TREE_PURPOSE (elem), index);
                         elem = TREE_CHAIN (elem))
                      ;

                    if (elem)
                      return expand_expr_unaligned (fold (TREE_VALUE (elem)),
                                                    palign);
                  }
              }
          }
      }

      /* ... fall through ... */

    case COMPONENT_REF:
    case BIT_FIELD_REF:
      /* If the operand is a CONSTRUCTOR, we can just extract the
         appropriate field if it is present.  Don't do this if we have
         already written the data since we want to refer to that copy
         and varasm.c assumes that's what we'll do.  */
      if (TREE_CODE (exp) != ARRAY_REF
          && TREE_CODE (TREE_OPERAND (exp, 0)) == CONSTRUCTOR
          && TREE_CST_RTL (TREE_OPERAND (exp, 0)) == 0)
        {
          tree elt;

          for (elt = CONSTRUCTOR_ELTS (TREE_OPERAND (exp, 0)); elt;
               elt = TREE_CHAIN (elt))
            if (TREE_PURPOSE (elt) == TREE_OPERAND (exp, 1))
              /* Note that unlike the case in expand_expr, we know this is
                 BLKmode and hence not an integer.  */
              return expand_expr_unaligned (TREE_VALUE (elt), palign);
        }

      {
        enum machine_mode mode1;
        HOST_WIDE_INT bitsize, bitpos;
        tree offset;
        int volatilep = 0;
        unsigned int alignment;
        int unsignedp;
        tree tem = get_inner_reference (exp, &bitsize, &bitpos, &offset,
                                        &mode1, &unsignedp, &volatilep,
                                        &alignment);

        /* If we got back the original object, something is wrong.  Perhaps
           we are evaluating an expression too early.  In any event, don't
           infinitely recurse.  */
        if (tem == exp)
          abort ();

        op0 = expand_expr (tem, NULL_RTX, VOIDmode, EXPAND_NORMAL);

        /* If this is a constant, put it into a register if it is a
           legitimate constant and OFFSET is 0 and memory if it isn't.  */
        if (CONSTANT_P (op0))
          {
            enum machine_mode inner_mode = TYPE_MODE (TREE_TYPE (tem));

            if (inner_mode != BLKmode && LEGITIMATE_CONSTANT_P (op0)
                && offset == 0)
              op0 = force_reg (inner_mode, op0);
            else
              op0 = validize_mem (force_const_mem (inner_mode, op0));
          }

        if (offset != 0)
          {
            rtx offset_rtx = expand_expr (offset, NULL_RTX, VOIDmode, 0);

            /* If this object is in a register, put it into memory.
               This case can't occur in C, but can in Ada if we have
               unchecked conversion of an expression from a scalar type to
               an array or record type.  */
            if (GET_CODE (op0) == REG || GET_CODE (op0) == SUBREG
                || GET_CODE (op0) == CONCAT || GET_CODE (op0) == ADDRESSOF)
              {
                rtx memloc = assign_temp (TREE_TYPE (tem), 1, 1, 1);

                mark_temp_addr_taken (memloc);
                emit_move_insn (memloc, op0);
                op0 = memloc;
              }

            if (GET_CODE (op0) != MEM)
              abort ();

            if (GET_MODE (offset_rtx) != ptr_mode)
              {
#ifdef POINTERS_EXTEND_UNSIGNED
                offset_rtx = convert_memory_address (ptr_mode, offset_rtx);
#else
                offset_rtx = convert_to_mode (ptr_mode, offset_rtx, 0);
#endif
              }

            op0 = change_address (op0, VOIDmode,
                                  gen_rtx_PLUS (ptr_mode, XEXP (op0, 0),
                                                force_reg (ptr_mode,
                                                           offset_rtx)));
          }

        /* Don't forget about volatility even if this is a bitfield.  */
        if (GET_CODE (op0) == MEM && volatilep && ! MEM_VOLATILE_P (op0))
          {
            op0 = copy_rtx (op0);
            MEM_VOLATILE_P (op0) = 1;
          }

        /* Check the access.  */
        if (current_function_check_memory_usage && GET_CODE (op0) == MEM)
          {
            rtx to;
            int size;

            to = plus_constant (XEXP (op0, 0), (bitpos / BITS_PER_UNIT));
            size = (bitpos % BITS_PER_UNIT) + bitsize + BITS_PER_UNIT - 1;

            /* Check the access right of the pointer.  */
            in_check_memory_usage = 1;
            if (size > BITS_PER_UNIT)
              emit_library_call (chkr_check_addr_libfunc, 1, VOIDmode, 3,
                                 to, ptr_mode, GEN_INT (size / BITS_PER_UNIT),
                                 TYPE_MODE (sizetype),
                                 GEN_INT (MEMORY_USE_RO), 
                                 TYPE_MODE (integer_type_node));
            in_check_memory_usage = 0;
          }

        /* In cases where an aligned union has an unaligned object
           as a field, we might be extracting a BLKmode value from
           an integer-mode (e.g., SImode) object.  Handle this case
           by doing the extract into an object as wide as the field
           (which we know to be the width of a basic mode), then
           storing into memory, and changing the mode to BLKmode.
           If we ultimately want the address (EXPAND_CONST_ADDRESS or
           EXPAND_INITIALIZER), then we must not copy to a temporary.  */
        if (mode1 == VOIDmode
            || GET_CODE (op0) == REG || GET_CODE (op0) == SUBREG
            || (SLOW_UNALIGNED_ACCESS (mode1, alignment)
                && (TYPE_ALIGN (type) > alignment
                    || bitpos % TYPE_ALIGN (type) != 0)))
          {
            enum machine_mode ext_mode = mode_for_size (bitsize, MODE_INT, 1);

            if (ext_mode == BLKmode)
              {
                /* In this case, BITPOS must start at a byte boundary.  */
                if (GET_CODE (op0) != MEM
                    || bitpos % BITS_PER_UNIT != 0)
                  abort ();

                op0 = change_address (op0, VOIDmode,
                                      plus_constant (XEXP (op0, 0),
                                                     bitpos / BITS_PER_UNIT));
              }
            else
              {
                rtx new = assign_stack_temp (ext_mode,
                                             bitsize / BITS_PER_UNIT, 0);

                op0 = extract_bit_field (validize_mem (op0), bitsize, bitpos,
                                         unsignedp, NULL_RTX, ext_mode,
                                         ext_mode, alignment,
                                         int_size_in_bytes (TREE_TYPE (tem)));

                /* If the result is a record type and BITSIZE is narrower than
                   the mode of OP0, an integral mode, and this is a big endian
                   machine, we must put the field into the high-order bits.  */
                if (TREE_CODE (type) == RECORD_TYPE && BYTES_BIG_ENDIAN
                    && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT
                    && bitsize < GET_MODE_BITSIZE (GET_MODE (op0)))
                  op0 = expand_shift (LSHIFT_EXPR, GET_MODE (op0), op0,
                                      size_int (GET_MODE_BITSIZE
                                                (GET_MODE (op0))
                                                - bitsize),
                                      op0, 1);


                emit_move_insn (new, op0);
                op0 = copy_rtx (new);
                PUT_MODE (op0, BLKmode);
              }
          }
        else
          /* Get a reference to just this component.  */
          op0 = change_address (op0, mode1,
                                  plus_constant (XEXP (op0, 0),
                                                 (bitpos / BITS_PER_UNIT)));

        MEM_ALIAS_SET (op0) = get_alias_set (exp);

        /* Adjust the alignment in case the bit position is not
           a multiple of the alignment of the inner object.  */
        while (bitpos % alignment != 0)
          alignment >>= 1;

        if (GET_CODE (XEXP (op0, 0)) == REG)
          mark_reg_pointer (XEXP (op0, 0), alignment);

        MEM_IN_STRUCT_P (op0) = 1;
        MEM_VOLATILE_P (op0) |= volatilep;

        *palign = alignment;
        return op0;
      }

    default:
      break;

    }

  return expand_expr (exp, NULL_RTX, VOIDmode, EXPAND_NORMAL);
}
\f
/* Return the tree node if a ARG corresponds to a string constant or zero
   if it doesn't.  If we return non-zero, set *PTR_OFFSET to the offset
   in bytes within the string that ARG is accessing.  The type of the
   offset will be `sizetype'.  */

tree
string_constant (arg, ptr_offset)
     tree arg;
     tree *ptr_offset;
{
  STRIP_NOPS (arg);

  if (TREE_CODE (arg) == ADDR_EXPR
      && TREE_CODE (TREE_OPERAND (arg, 0)) == STRING_CST)
    {
      *ptr_offset = size_zero_node;
      return TREE_OPERAND (arg, 0);
    }
  else if (TREE_CODE (arg) == PLUS_EXPR)
    {
      tree arg0 = TREE_OPERAND (arg, 0);
      tree arg1 = TREE_OPERAND (arg, 1);

      STRIP_NOPS (arg0);
      STRIP_NOPS (arg1);

      if (TREE_CODE (arg0) == ADDR_EXPR
          && TREE_CODE (TREE_OPERAND (arg0, 0)) == STRING_CST)
        {
          *ptr_offset = convert (sizetype, arg1);
          return TREE_OPERAND (arg0, 0);
        }
      else if (TREE_CODE (arg1) == ADDR_EXPR
               && TREE_CODE (TREE_OPERAND (arg1, 0)) == STRING_CST)
        {
          *ptr_offset = convert (sizetype, arg0);
          return TREE_OPERAND (arg1, 0);
        }
    }

  return 0;
}
\f
/* Expand code for a post- or pre- increment or decrement
   and return the RTX for the result.
   POST is 1 for postinc/decrements and 0 for preinc/decrements.  */

static rtx
expand_increment (exp, post, ignore)
     register tree exp;
     int post, ignore;
{
  register rtx op0, op1;
  register rtx temp, value;
  register tree incremented = TREE_OPERAND (exp, 0);
  optab this_optab = add_optab;
  int icode;
  enum machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
  int op0_is_copy = 0;
  int single_insn = 0;
  /* 1 means we can't store into OP0 directly,
     because it is a subreg narrower than a word,
     and we don't dare clobber the rest of the word.  */
  int bad_subreg = 0;

  /* Stabilize any component ref that might need to be
     evaluated more than once below.  */
  if (!post
      || TREE_CODE (incremented) == BIT_FIELD_REF
      || (TREE_CODE (incremented) == COMPONENT_REF
          && (TREE_CODE (TREE_OPERAND (incremented, 0)) != INDIRECT_REF
              || DECL_BIT_FIELD (TREE_OPERAND (incremented, 1)))))
    incremented = stabilize_reference (incremented);
  /* Nested *INCREMENT_EXPRs can happen in C++.  We must force innermost
     ones into save exprs so that they don't accidentally get evaluated
     more than once by the code below.  */
  if (TREE_CODE (incremented) == PREINCREMENT_EXPR
      || TREE_CODE (incremented) == PREDECREMENT_EXPR)
    incremented = save_expr (incremented);

  /* Compute the operands as RTX.
     Note whether OP0 is the actual lvalue or a copy of it:
     I believe it is a copy iff it is a register or subreg
     and insns were generated in computing it.   */

  temp = get_last_insn ();
  op0 = expand_expr (incremented, NULL_RTX, VOIDmode, EXPAND_MEMORY_USE_RW);

  /* If OP0 is a SUBREG made for a promoted variable, we cannot increment
     in place but instead must do sign- or zero-extension during assignment,
     so we copy it into a new register and let the code below use it as
     a copy.

     Note that we can safely modify this SUBREG since it is know not to be
     shared (it was made by the expand_expr call above).  */

  if (GET_CODE (op0) == SUBREG && SUBREG_PROMOTED_VAR_P (op0))
    {
      if (post)
        SUBREG_REG (op0) = copy_to_reg (SUBREG_REG (op0));
      else
        bad_subreg = 1;
    }
  else if (GET_CODE (op0) == SUBREG
           && GET_MODE_BITSIZE (GET_MODE (op0)) < BITS_PER_WORD)
    {
      /* We cannot increment this SUBREG in place.  If we are
         post-incrementing, get a copy of the old value.  Otherwise,
         just mark that we cannot increment in place.  */
      if (post)
        op0 = copy_to_reg (op0);
      else
        bad_subreg = 1;
    }

  op0_is_copy = ((GET_CODE (op0) == SUBREG || GET_CODE (op0) == REG)
                 && temp != get_last_insn ());
  op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode,
                     EXPAND_MEMORY_USE_BAD);

  /* Decide whether incrementing or decrementing.  */
  if (TREE_CODE (exp) == POSTDECREMENT_EXPR
      || TREE_CODE (exp) == PREDECREMENT_EXPR)
    this_optab = sub_optab;

  /* Convert decrement by a constant into a negative increment.  */
  if (this_optab == sub_optab
      && GET_CODE (op1) == CONST_INT)
    {
      op1 = GEN_INT (- INTVAL (op1));
      this_optab = add_optab;
    }

  /* For a preincrement, see if we can do this with a single instruction.  */
  if (!post)
    {
      icode = (int) this_optab->handlers[(int) mode].insn_code;
      if (icode != (int) CODE_FOR_nothing
          /* Make sure that OP0 is valid for operands 0 and 1
             of the insn we want to queue.  */
          && (*insn_data[icode].operand[0].predicate) (op0, mode)
          && (*insn_data[icode].operand[1].predicate) (op0, mode)
          && (*insn_data[icode].operand[2].predicate) (op1, mode))
        single_insn = 1;
    }

  /* If OP0 is not the actual lvalue, but rather a copy in a register,
     then we cannot just increment OP0.  We must therefore contrive to
     increment the original value.  Then, for postincrement, we can return
     OP0 since it is a copy of the old value.  For preincrement, expand here
     unless we can do it with a single insn.

     Likewise if storing directly into OP0 would clobber high bits
     we need to preserve (bad_subreg).  */
  if (op0_is_copy || (!post && !single_insn) || bad_subreg)
    {
      /* This is the easiest way to increment the value wherever it is.
         Problems with multiple evaluation of INCREMENTED are prevented
         because either (1) it is a component_ref or preincrement,
         in which case it was stabilized above, or (2) it is an array_ref
         with constant index in an array in a register, which is
         safe to reevaluate.  */
      tree newexp = build (((TREE_CODE (exp) == POSTDECREMENT_EXPR
                             || TREE_CODE (exp) == PREDECREMENT_EXPR)
                            ? MINUS_EXPR : PLUS_EXPR),
                           TREE_TYPE (exp),
                           incremented,
                           TREE_OPERAND (exp, 1));

      while (TREE_CODE (incremented) == NOP_EXPR
             || TREE_CODE (incremented) == CONVERT_EXPR)
        {
          newexp = convert (TREE_TYPE (incremented), newexp);
          incremented = TREE_OPERAND (incremented, 0);
        }

      temp = expand_assignment (incremented, newexp, ! post && ! ignore , 0);
      return post ? op0 : temp;
    }

  if (post)
    {
      /* We have a true reference to the value in OP0.
         If there is an insn to add or subtract in this mode, queue it.
         Queueing the increment insn avoids the register shuffling
         that often results if we must increment now and first save
         the old value for subsequent use.  */

#if 0  /* Turned off to avoid making extra insn for indexed memref.  */
      op0 = stabilize (op0);
#endif

      icode = (int) this_optab->handlers[(int) mode].insn_code;
      if (icode != (int) CODE_FOR_nothing
          /* Make sure that OP0 is valid for operands 0 and 1
             of the insn we want to queue.  */
          && (*insn_data[icode].operand[0].predicate) (op0, mode)
          && (*insn_data[icode].operand[1].predicate) (op0, mode))
        {
          if (! (*insn_data[icode].operand[2].predicate) (op1, mode))
            op1 = force_reg (mode, op1);

          return enqueue_insn (op0, GEN_FCN (icode) (op0, op0, op1));
        }
      if (icode != (int) CODE_FOR_nothing && GET_CODE (op0) == MEM)
        {
          rtx addr = (general_operand (XEXP (op0, 0), mode)
                      ? force_reg (Pmode, XEXP (op0, 0))
                      : copy_to_reg (XEXP (op0, 0)));
          rtx temp, result;

          op0 = change_address (op0, VOIDmode, addr);
          temp = force_reg (GET_MODE (op0), op0);
          if (! (*insn_data[icode].operand[2].predicate) (op1, mode))
            op1 = force_reg (mode, op1);

          /* The increment queue is LIFO, thus we have to `queue'
             the instructions in reverse order.  */
          enqueue_insn (op0, gen_move_insn (op0, temp));
          result = enqueue_insn (temp, GEN_FCN (icode) (temp, temp, op1));
          return result;
        }
    }

  /* Preincrement, or we can't increment with one simple insn.  */
  if (post)
    /* Save a copy of the value before inc or dec, to return it later.  */
    temp = value = copy_to_reg (op0);
  else
    /* Arrange to return the incremented value.  */
    /* Copy the rtx because expand_binop will protect from the queue,
       and the results of that would be invalid for us to return
       if our caller does emit_queue before using our result.  */
    temp = copy_rtx (value = op0);

  /* Increment however we can.  */
  op1 = expand_binop (mode, this_optab, value, op1,
                      current_function_check_memory_usage ? NULL_RTX : op0,
                      TREE_UNSIGNED (TREE_TYPE (exp)), OPTAB_LIB_WIDEN);
  /* Make sure the value is stored into OP0.  */
  if (op1 != op0)
    emit_move_insn (op0, op1);

  return temp;
}
\f
/* Expand all function calls contained within EXP, innermost ones first.
   But don't look within expressions that have sequence points.
   For each CALL_EXPR, record the rtx for its value
   in the CALL_EXPR_RTL field.  */

static void
preexpand_calls (exp)
     tree exp;
{
  register int nops, i;
  int class = TREE_CODE_CLASS (TREE_CODE (exp));

  if (! do_preexpand_calls)
    return;

  /* Only expressions and references can contain calls.  */

  if (! IS_EXPR_CODE_CLASS (class) && class != 'r')
    return;

  switch (TREE_CODE (exp))
    {
    case CALL_EXPR:
      /* Do nothing if already expanded.  */
      if (CALL_EXPR_RTL (exp) != 0
          /* Do nothing if the call returns a variable-sized object.  */
          || (TREE_CODE (TREE_TYPE (exp)) != VOID_TYPE
              && TREE_CODE (TYPE_SIZE (TREE_TYPE (exp))) != INTEGER_CST)
          /* Do nothing to built-in functions.  */
          || (TREE_CODE (TREE_OPERAND (exp, 0)) == ADDR_EXPR
              && (TREE_CODE (TREE_OPERAND (TREE_OPERAND (exp, 0), 0))
                  == FUNCTION_DECL)
              && DECL_BUILT_IN (TREE_OPERAND (TREE_OPERAND (exp, 0), 0))))
        return;

      CALL_EXPR_RTL (exp) = expand_call (exp, NULL_RTX, 0);
      return;

    case COMPOUND_EXPR:
    case COND_EXPR:
    case TRUTH_ANDIF_EXPR:
    case TRUTH_ORIF_EXPR:
      /* If we find one of these, then we can be sure
         the adjust will be done for it (since it makes jumps).
         Do it now, so that if this is inside an argument
         of a function, we don't get the stack adjustment
         after some other args have already been pushed.  */
      do_pending_stack_adjust ();
      return;

    case BLOCK:
    case RTL_EXPR:
    case WITH_CLEANUP_EXPR:
    case CLEANUP_POINT_EXPR:
    case TRY_CATCH_EXPR:
      return;

    case SAVE_EXPR:
      if (SAVE_EXPR_RTL (exp) != 0)
        return;
      
    default:
      break;
    }

  nops = TREE_CODE_LENGTH (TREE_CODE (exp));
  for (i = 0; i < nops; i++)
    if (TREE_OPERAND (exp, i) != 0)
      {
        if (TREE_CODE (exp) == TARGET_EXPR && i == 2)
          /* We don't need to preexpand the cleanup for a TARGET_EXPR.
             It doesn't happen before the call is made.  */
          ;
        else
          {
            class = TREE_CODE_CLASS (TREE_CODE (TREE_OPERAND (exp, i)));
            if (IS_EXPR_CODE_CLASS (class) || class == 'r')
              preexpand_calls (TREE_OPERAND (exp, i));
          }
      }
}
\f
/* At the start of a function, record that we have no previously-pushed
   arguments waiting to be popped.  */

void
init_pending_stack_adjust ()
{
  pending_stack_adjust = 0;
}

/* When exiting from function, if safe, clear out any pending stack adjust
   so the adjustment won't get done.

   Note, if the current function calls alloca, then it must have a
   frame pointer regardless of the value of flag_omit_frame_pointer.  */

void
clear_pending_stack_adjust ()
{
#ifdef EXIT_IGNORE_STACK
  if (optimize > 0
      && (! flag_omit_frame_pointer || current_function_calls_alloca)
      && EXIT_IGNORE_STACK
      && ! (DECL_INLINE (current_function_decl) && ! flag_no_inline)
      && ! flag_inline_functions)
    {
      stack_pointer_delta -= pending_stack_adjust,
      pending_stack_adjust = 0;
    }
#endif
}

/* Pop any previously-pushed arguments that have not been popped yet.  */

void
do_pending_stack_adjust ()
{
  if (inhibit_defer_pop == 0)
    {
      if (pending_stack_adjust != 0)
        adjust_stack (GEN_INT (pending_stack_adjust));
      pending_stack_adjust = 0;
    }
}
\f
/* Expand conditional expressions.  */

/* Generate code to evaluate EXP and jump to LABEL if the value is zero.
   LABEL is an rtx of code CODE_LABEL, in this function and all the
   functions here.  */

void
jumpifnot (exp, label)
     tree exp;
     rtx label;
{
  do_jump (exp, label, NULL_RTX);
}

/* Generate code to evaluate EXP and jump to LABEL if the value is nonzero.  */

void
jumpif (exp, label)
     tree exp;
     rtx label;
{
  do_jump (exp, NULL_RTX, label);
}

/* Generate code to evaluate EXP and jump to IF_FALSE_LABEL if
   the result is zero, or IF_TRUE_LABEL if the result is one.
   Either of IF_FALSE_LABEL and IF_TRUE_LABEL may be zero,
   meaning fall through in that case.

   do_jump always does any pending stack adjust except when it does not
   actually perform a jump.  An example where there is no jump
   is when EXP is `(foo (), 0)' and IF_FALSE_LABEL is null.

   This function is responsible for optimizing cases such as
   &&, || and comparison operators in EXP.  */

void
do_jump (exp, if_false_label, if_true_label)
     tree exp;
     rtx if_false_label, if_true_label;
{
  register enum tree_code code = TREE_CODE (exp);
  /* Some cases need to create a label to jump to
     in order to properly fall through.
     These cases set DROP_THROUGH_LABEL nonzero.  */
  rtx drop_through_label = 0;
  rtx temp;
  int i;
  tree type;
  enum machine_mode mode;

#ifdef MAX_INTEGER_COMPUTATION_MODE
  check_max_integer_computation_mode (exp);
#endif

  emit_queue ();

  switch (code)
    {
    case ERROR_MARK:
      break;

    case INTEGER_CST:
      temp = integer_zerop (exp) ? if_false_label : if_true_label;
      if (temp)
        emit_jump (temp);
      break;

#if 0
      /* This is not true with #pragma weak  */
    case ADDR_EXPR:
      /* The address of something can never be zero.  */
      if (if_true_label)
        emit_jump (if_true_label);
      break;
#endif

    case NOP_EXPR:
      if (TREE_CODE (TREE_OPERAND (exp, 0)) == COMPONENT_REF
          || TREE_CODE (TREE_OPERAND (exp, 0)) == BIT_FIELD_REF
          || TREE_CODE (TREE_OPERAND (exp, 0)) == ARRAY_REF)
        goto normal;
    case CONVERT_EXPR:
      /* If we are narrowing the operand, we have to do the compare in the
         narrower mode.  */
      if ((TYPE_PRECISION (TREE_TYPE (exp))
           < TYPE_PRECISION (TREE_TYPE (TREE_OPERAND (exp, 0)))))
        goto normal;
    case NON_LVALUE_EXPR:
    case REFERENCE_EXPR:
    case ABS_EXPR:
    case NEGATE_EXPR:
    case LROTATE_EXPR:
    case RROTATE_EXPR:
      /* These cannot change zero->non-zero or vice versa.  */
      do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
      break;

    case WITH_RECORD_EXPR:
      /* Put the object on the placeholder list, recurse through our first
         operand, and pop the list.  */
      placeholder_list = tree_cons (TREE_OPERAND (exp, 1), NULL_TREE,
                                    placeholder_list);
      do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);
      placeholder_list = TREE_CHAIN (placeholder_list);
      break;

#if 0
      /* This is never less insns than evaluating the PLUS_EXPR followed by
         a test and can be longer if the test is eliminated.  */
    case PLUS_EXPR:
      /* Reduce to minus.  */
      exp = build (MINUS_EXPR, TREE_TYPE (exp),
                   TREE_OPERAND (exp, 0),
                   fold (build1 (NEGATE_EXPR, TREE_TYPE (TREE_OPERAND (exp, 1)),
                                 TREE_OPERAND (exp, 1))));
      /* Process as MINUS.  */
#endif

    case MINUS_EXPR:
      /* Non-zero iff operands of minus differ.  */
      do_compare_and_jump (build (NE_EXPR, TREE_TYPE (exp),
                                  TREE_OPERAND (exp, 0),
                                  TREE_OPERAND (exp, 1)),
                           NE, NE, if_false_label, if_true_label);
      break;

    case BIT_AND_EXPR:
      /* If we are AND'ing with a small constant, do this comparison in the
         smallest type that fits.  If the machine doesn't have comparisons
         that small, it will be converted back to the wider comparison.
         This helps if we are testing the sign bit of a narrower object.
         combine can't do this for us because it can't know whether a
         ZERO_EXTRACT or a compare in a smaller mode exists, but we do.  */

      if (! SLOW_BYTE_ACCESS
          && TREE_CODE (TREE_OPERAND (exp, 1)) == INTEGER_CST
          && TYPE_PRECISION (TREE_TYPE (exp)) <= HOST_BITS_PER_WIDE_INT
          && (i = tree_floor_log2 (TREE_OPERAND (exp, 1))) >= 0
          && (mode = mode_for_size (i + 1, MODE_INT, 0)) != BLKmode
          && (type = type_for_mode (mode, 1)) != 0
          && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
          && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
              != CODE_FOR_nothing))
        {
          do_jump (convert (type, exp), if_false_label, if_true_label);
          break;
        }
      goto normal;

    case TRUTH_NOT_EXPR:
      do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);
      break;

    case TRUTH_ANDIF_EXPR:
      if (if_false_label == 0)
        if_false_label = drop_through_label = gen_label_rtx ();
      do_jump (TREE_OPERAND (exp, 0), if_false_label, NULL_RTX);
      start_cleanup_deferral ();
      do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
      end_cleanup_deferral ();
      break;

    case TRUTH_ORIF_EXPR:
      if (if_true_label == 0)
        if_true_label = drop_through_label = gen_label_rtx ();
      do_jump (TREE_OPERAND (exp, 0), NULL_RTX, if_true_label);
      start_cleanup_deferral ();
      do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
      end_cleanup_deferral ();
      break;

    case COMPOUND_EXPR:
      push_temp_slots ();
      expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
      preserve_temp_slots (NULL_RTX);
      free_temp_slots ();
      pop_temp_slots ();
      emit_queue ();
      do_pending_stack_adjust ();
      do_jump (TREE_OPERAND (exp, 1), if_false_label, if_true_label);
      break;

    case COMPONENT_REF:
    case BIT_FIELD_REF:
    case ARRAY_REF:
      {
        HOST_WIDE_INT bitsize, bitpos;
        int unsignedp;
        enum machine_mode mode;
        tree type;
        tree offset;
        int volatilep = 0;
        unsigned int alignment;

        /* Get description of this reference.  We don't actually care
           about the underlying object here.  */
        get_inner_reference (exp, &bitsize, &bitpos, &offset, &mode,
                             &unsignedp, &volatilep, &alignment);

        type = type_for_size (bitsize, unsignedp);
        if (! SLOW_BYTE_ACCESS
            && type != 0 && bitsize >= 0
            && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (exp))
            && (cmp_optab->handlers[(int) TYPE_MODE (type)].insn_code
                != CODE_FOR_nothing))
          {
            do_jump (convert (type, exp), if_false_label, if_true_label);
            break;
          }
        goto normal;
      }

    case COND_EXPR:
      /* Do (a ? 1 : 0) and (a ? 0 : 1) as special cases.  */
      if (integer_onep (TREE_OPERAND (exp, 1))
          && integer_zerop (TREE_OPERAND (exp, 2)))
        do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);

      else if (integer_zerop (TREE_OPERAND (exp, 1))
               && integer_onep (TREE_OPERAND (exp, 2)))
        do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);

      else
        {
          register rtx label1 = gen_label_rtx ();
          drop_through_label = gen_label_rtx ();

          do_jump (TREE_OPERAND (exp, 0), label1, NULL_RTX);

          start_cleanup_deferral ();
          /* Now the THEN-expression.  */
          do_jump (TREE_OPERAND (exp, 1),
                   if_false_label ? if_false_label : drop_through_label,
                   if_true_label ? if_true_label : drop_through_label);
          /* In case the do_jump just above never jumps.  */
          do_pending_stack_adjust ();
          emit_label (label1);

          /* Now the ELSE-expression.  */
          do_jump (TREE_OPERAND (exp, 2),
                   if_false_label ? if_false_label : drop_through_label,
                   if_true_label ? if_true_label : drop_through_label);
          end_cleanup_deferral ();
        }
      break;

    case EQ_EXPR:
      {
        tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));

        if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_FLOAT
            || GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_INT)
          {
            tree exp0 = save_expr (TREE_OPERAND (exp, 0));
            tree exp1 = save_expr (TREE_OPERAND (exp, 1));
            do_jump
              (fold
               (build (TRUTH_ANDIF_EXPR, TREE_TYPE (exp),
                       fold (build (EQ_EXPR, TREE_TYPE (exp),
                                    fold (build1 (REALPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp0)),
                                    fold (build1 (REALPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp1)))),
                       fold (build (EQ_EXPR, TREE_TYPE (exp),
                                    fold (build1 (IMAGPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp0)),
                                    fold (build1 (IMAGPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp1)))))),
               if_false_label, if_true_label);
          }

        else if (integer_zerop (TREE_OPERAND (exp, 1)))
          do_jump (TREE_OPERAND (exp, 0), if_true_label, if_false_label);

        else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
                 && !can_compare_p (EQ, TYPE_MODE (inner_type), ccp_jump))
          do_jump_by_parts_equality (exp, if_false_label, if_true_label);
        else
          do_compare_and_jump (exp, EQ, EQ, if_false_label, if_true_label);
        break;
      }

    case NE_EXPR:
      {
        tree inner_type = TREE_TYPE (TREE_OPERAND (exp, 0));

        if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_FLOAT
            || GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_COMPLEX_INT)
          {
            tree exp0 = save_expr (TREE_OPERAND (exp, 0));
            tree exp1 = save_expr (TREE_OPERAND (exp, 1));
            do_jump
              (fold
               (build (TRUTH_ORIF_EXPR, TREE_TYPE (exp),
                       fold (build (NE_EXPR, TREE_TYPE (exp),
                                    fold (build1 (REALPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp0)),
                                    fold (build1 (REALPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp1)))),
                       fold (build (NE_EXPR, TREE_TYPE (exp),
                                    fold (build1 (IMAGPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp0)),
                                    fold (build1 (IMAGPART_EXPR,
                                                  TREE_TYPE (inner_type),
                                                  exp1)))))),
               if_false_label, if_true_label);
          }

        else if (integer_zerop (TREE_OPERAND (exp, 1)))
          do_jump (TREE_OPERAND (exp, 0), if_false_label, if_true_label);

        else if (GET_MODE_CLASS (TYPE_MODE (inner_type)) == MODE_INT
                 && !can_compare_p (NE, TYPE_MODE (inner_type), ccp_jump))
          do_jump_by_parts_equality (exp, if_true_label, if_false_label);
        else
          do_compare_and_jump (exp, NE, NE, if_false_label, if_true_label);
        break;
      }

    case LT_EXPR:
      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && ! can_compare_p (LT, mode, ccp_jump))
        do_jump_by_parts_greater (exp, 1, if_false_label, if_true_label);
      else
        do_compare_and_jump (exp, LT, LTU, if_false_label, if_true_label);
      break;

    case LE_EXPR:
      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && ! can_compare_p (LE, mode, ccp_jump))
        do_jump_by_parts_greater (exp, 0, if_true_label, if_false_label);
      else
        do_compare_and_jump (exp, LE, LEU, if_false_label, if_true_label);
      break;

    case GT_EXPR:
      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && ! can_compare_p (GT, mode, ccp_jump))
        do_jump_by_parts_greater (exp, 0, if_false_label, if_true_label);
      else
        do_compare_and_jump (exp, GT, GTU, if_false_label, if_true_label);
      break;

    case GE_EXPR:
      mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
      if (GET_MODE_CLASS (mode) == MODE_INT
          && ! can_compare_p (GE, mode, ccp_jump))
        do_jump_by_parts_greater (exp, 1, if_true_label, if_false_label);
      else
        do_compare_and_jump (exp, GE, GEU, if_false_label, if_true_label);
      break;

    case UNORDERED_EXPR:
    case ORDERED_EXPR:
      {
        enum rtx_code cmp, rcmp;
        int do_rev;

        if (code == UNORDERED_EXPR)
          cmp = UNORDERED, rcmp = ORDERED;
        else
          cmp = ORDERED, rcmp = UNORDERED;
        mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));

        do_rev = 0;
        if (! can_compare_p (cmp, mode, ccp_jump)
            && (can_compare_p (rcmp, mode, ccp_jump)
                /* If the target doesn't provide either UNORDERED or ORDERED
                   comparisons, canonicalize on UNORDERED for the library.  */
                || rcmp == UNORDERED))
          do_rev = 1;

        if (! do_rev)
          do_compare_and_jump (exp, cmp, cmp, if_false_label, if_true_label);
        else
          do_compare_and_jump (exp, rcmp, rcmp, if_true_label, if_false_label);
      }
      break;

    {
      enum rtx_code rcode1;
      enum tree_code tcode2;

      case UNLT_EXPR:
        rcode1 = UNLT;
        tcode2 = LT_EXPR;
        goto unordered_bcc;
      case UNLE_EXPR:
        rcode1 = UNLE;
        tcode2 = LE_EXPR;
        goto unordered_bcc;
      case UNGT_EXPR:
        rcode1 = UNGT;
        tcode2 = GT_EXPR;
        goto unordered_bcc;
      case UNGE_EXPR:
        rcode1 = UNGE;
        tcode2 = GE_EXPR;
        goto unordered_bcc;
      case UNEQ_EXPR:
        rcode1 = UNEQ;
        tcode2 = EQ_EXPR;
        goto unordered_bcc;

      unordered_bcc:
        mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
        if (can_compare_p (rcode1, mode, ccp_jump))
          do_compare_and_jump (exp, rcode1, rcode1, if_false_label,
                               if_true_label);
        else
          {
            tree op0 = save_expr (TREE_OPERAND (exp, 0));
            tree op1 = save_expr (TREE_OPERAND (exp, 1));
            tree cmp0, cmp1;

            /* If the target doesn't support combined unordered 
               compares, decompose into UNORDERED + comparison.  */
            cmp0 = fold (build (UNORDERED_EXPR, TREE_TYPE (exp), op0, op1));
            cmp1 = fold (build (tcode2, TREE_TYPE (exp), op0, op1));
            exp = build (TRUTH_ORIF_EXPR, TREE_TYPE (exp), cmp0, cmp1);
            do_jump (exp, if_false_label, if_true_label);
          }
      }
      break;

    default:
    normal:
      temp = expand_expr (exp, NULL_RTX, VOIDmode, 0);
#if 0
      /* This is not needed any more and causes poor code since it causes
         comparisons and tests from non-SI objects to have different code
         sequences.  */
      /* Copy to register to avoid generating bad insns by cse
         from (set (mem ...) (arithop))  (set (cc0) (mem ...)).  */
      if (!cse_not_expected && GET_CODE (temp) == MEM)
        temp = copy_to_reg (temp);
#endif
      do_pending_stack_adjust ();
      /* Do any postincrements in the expression that was tested.  */
      emit_queue ();

      if (GET_CODE (temp) == CONST_INT || GET_CODE (temp) == LABEL_REF)
        {
          rtx target = temp == const0_rtx ? if_false_label : if_true_label;
          if (target)
            emit_jump (target);
        }
      else if (GET_MODE_CLASS (GET_MODE (temp)) == MODE_INT
               && ! can_compare_p (NE, GET_MODE (temp), ccp_jump))
        /* Note swapping the labels gives us not-equal.  */
        do_jump_by_parts_equality_rtx (temp, if_true_label, if_false_label);
      else if (GET_MODE (temp) != VOIDmode)
        do_compare_rtx_and_jump (temp, CONST0_RTX (GET_MODE (temp)),
                                 NE, TREE_UNSIGNED (TREE_TYPE (exp)),
                                 GET_MODE (temp), NULL_RTX, 0,
                                 if_false_label, if_true_label);
      else
        abort ();
    }

  if (drop_through_label)
    {
      /* If do_jump produces code that might be jumped around,
         do any stack adjusts from that code, before the place
         where control merges in.  */
      do_pending_stack_adjust ();
      emit_label (drop_through_label);
    }
}
\f
/* Given a comparison expression EXP for values too wide to be compared
   with one insn, test the comparison and jump to the appropriate label.
   The code of EXP is ignored; we always test GT if SWAP is 0,
   and LT if SWAP is 1.  */

static void
do_jump_by_parts_greater (exp, swap, if_false_label, if_true_label)
     tree exp;
     int swap;
     rtx if_false_label, if_true_label;
{
  rtx op0 = expand_expr (TREE_OPERAND (exp, swap), NULL_RTX, VOIDmode, 0);
  rtx op1 = expand_expr (TREE_OPERAND (exp, !swap), NULL_RTX, VOIDmode, 0);
  enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
  int unsignedp = TREE_UNSIGNED (TREE_TYPE (TREE_OPERAND (exp, 0)));

  do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label, if_true_label);
}

/* Compare OP0 with OP1, word at a time, in mode MODE.
   UNSIGNEDP says to do unsigned comparison.
   Jump to IF_TRUE_LABEL if OP0 is greater, IF_FALSE_LABEL otherwise.  */

void
do_jump_by_parts_greater_rtx (mode, unsignedp, op0, op1, if_false_label, if_true_label)
     enum machine_mode mode;
     int unsignedp;
     rtx op0, op1;
     rtx if_false_label, if_true_label;
{
  int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
  rtx drop_through_label = 0;
  int i;

  if (! if_true_label || ! if_false_label)
    drop_through_label = gen_label_rtx ();
  if (! if_true_label)
    if_true_label = drop_through_label;
  if (! if_false_label)
    if_false_label = drop_through_label;

  /* Compare a word at a time, high order first.  */
  for (i = 0; i < nwords; i++)
    {
      rtx op0_word, op1_word;

      if (WORDS_BIG_ENDIAN)
        {
          op0_word = operand_subword_force (op0, i, mode);
          op1_word = operand_subword_force (op1, i, mode);
        }
      else
        {
          op0_word = operand_subword_force (op0, nwords - 1 - i, mode);
          op1_word = operand_subword_force (op1, nwords - 1 - i, mode);
        }

      /* All but high-order word must be compared as unsigned.  */
      do_compare_rtx_and_jump (op0_word, op1_word, GT,
                               (unsignedp || i > 0), word_mode, NULL_RTX, 0,
                               NULL_RTX, if_true_label);

      /* Consider lower words only if these are equal.  */
      do_compare_rtx_and_jump (op0_word, op1_word, NE, unsignedp, word_mode,
                               NULL_RTX, 0, NULL_RTX, if_false_label);
    }

  if (if_false_label)
    emit_jump (if_false_label);
  if (drop_through_label)
    emit_label (drop_through_label);
}

/* Given an EQ_EXPR expression EXP for values too wide to be compared
   with one insn, test the comparison and jump to the appropriate label.  */

static void
do_jump_by_parts_equality (exp, if_false_label, if_true_label)
     tree exp;
     rtx if_false_label, if_true_label;
{
  rtx op0 = expand_expr (TREE_OPERAND (exp, 0), NULL_RTX, VOIDmode, 0);
  rtx op1 = expand_expr (TREE_OPERAND (exp, 1), NULL_RTX, VOIDmode, 0);
  enum machine_mode mode = TYPE_MODE (TREE_TYPE (TREE_OPERAND (exp, 0)));
  int nwords = (GET_MODE_SIZE (mode) / UNITS_PER_WORD);
  int i;
  rtx drop_through_label = 0;

  if (! if_false_label)
    drop_through_label = if_false_label = gen_label_rtx ();

  for (i = 0; i < nwords; i++)
    do_compare_rtx_and_jump (operand_subword_force (op0, i, mode),
                             operand_subword_force (op1, i, mode),
                             EQ, TREE_UNSIGNED (TREE_TYPE (exp)),
                             word_mode, NULL_RTX, 0, if_false_label,
                             NULL_RTX);

  if (if_true_label)
    emit_jump (if_true_label);
  if (drop_through_label)
    emit_label (drop_through_label);
}
\f
/* Jump according to whether OP0 is 0.
   We assume that OP0 has an integer mode that is too wide
   for the available compare insns.  */

void
do_jump_by_parts_equality_rtx (op0, if_false_label, if_true_label)
     rtx op0;
     rtx if_false_label, if_true_label;
{
  int nwords = GET_MODE_SIZE (GET_MODE (op0)) / UNITS_PER_WORD;
  rtx part;
  int i;
  rtx drop_through_label = 0;

  /* The fastest way of doing this comparison on almost any machine is to
     "or" all the words and compare the result.  If all have to be loaded
     from memory and this is a very wide item, it's possible this may
     be slower, but that's highly unlikely.  */

  part = gen_reg_rtx (word_mode);
  emit_move_insn (part, operand_subword_force (op0, 0, GET_MODE (op0)));
  for (i = 1; i < nwords && part != 0; i++)
    part = expand_binop (word_mode, ior_optab, part,
                         operand_subword_force (op0, i, GET_MODE (op0)),
                         part, 1, OPTAB_WIDEN);

  if (part != 0)
    {
      do_compare_rtx_and_jump (part, const0_rtx, EQ, 1, word_mode,
                               NULL_RTX, 0, if_false_label, if_true_label);

      return;
    }

  /* If we couldn't do the "or" simply, do this with a series of compares.  */
  if (! if_false_label)
    drop_through_label = if_false_label = gen_label_rtx ();

  for (i = 0; i < nwords; i++)
    do_compare_rtx_and_jump (operand_subword_force (op0, i, GET_MODE (op0)),
                             const0_rtx, EQ, 1, word_mode, NULL_RTX, 0,
                             if_false_label, NULL_RTX);

  if (if_true_label)
    emit_jump (if_true_label);

  if (drop_through_label)
    emit_label (drop_through_label);
}
\f
/* Generate code for a comparison of OP0 and OP1 with rtx code CODE.
   (including code to compute the values to be compared)
   and set (CC0) according to the result.
   The decision as to signed or unsigned comparison must be made by the caller.

   We force a stack adjustment unless there are currently
   things pushed on the stack that aren't yet used.

   If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
   compared.

   If ALIGN is non-zero, it is the alignment of this type; if zero, the
   size of MODE should be used.  */

rtx
compare_from_rtx (op0, op1, code, unsignedp, mode, size, align)
     register rtx op0, op1;
     enum rtx_code code;
     int unsignedp;
     enum machine_mode mode;
     rtx size;
     unsigned int align;
{
  rtx tem;

  /* If one operand is constant, make it the second one.  Only do this
     if the other operand is not constant as well.  */

  if ((CONSTANT_P (op0) && ! CONSTANT_P (op1))
      || (GET_CODE (op0) == CONST_INT && GET_CODE (op1) != CONST_INT))
    {
      tem = op0;
      op0 = op1;
      op1 = tem;
      code = swap_condition (code);
    }

  if (flag_force_mem)
    {
      op0 = force_not_mem (op0);
      op1 = force_not_mem (op1);
    }

  do_pending_stack_adjust ();

  if (GET_CODE (op0) == CONST_INT && GET_CODE (op1) == CONST_INT
      && (tem = simplify_relational_operation (code, mode, op0, op1)) != 0)
    return tem;

#if 0
  /* There's no need to do this now that combine.c can eliminate lots of
     sign extensions.  This can be less efficient in certain cases on other
     machines.  */

  /* If this is a signed equality comparison, we can do it as an
     unsigned comparison since zero-extension is cheaper than sign
     extension and comparisons with zero are done as unsigned.  This is
     the case even on machines that can do fast sign extension, since
     zero-extension is easier to combine with other operations than
     sign-extension is.  If we are comparing against a constant, we must
     convert it to what it would look like unsigned.  */
  if ((code == EQ || code == NE) && ! unsignedp
      && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
    {
      if (GET_CODE (op1) == CONST_INT
          && (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0))) != INTVAL (op1))
        op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0)));
      unsignedp = 1;
    }
#endif
        
  emit_cmp_insn (op0, op1, code, size, mode, unsignedp, align);

  return gen_rtx_fmt_ee (code, VOIDmode, cc0_rtx, const0_rtx);
}

/* Like do_compare_and_jump but expects the values to compare as two rtx's.
   The decision as to signed or unsigned comparison must be made by the caller.

   If MODE is BLKmode, SIZE is an RTX giving the size of the objects being
   compared.

   If ALIGN is non-zero, it is the alignment of this type; if zero, the
   size of MODE should be used.  */

void
do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode, size, align,
                         if_false_label, if_true_label)
     register rtx op0, op1;
     enum rtx_code code;
     int unsignedp;
     enum machine_mode mode;
     rtx size;
     unsigned int align;
     rtx if_false_label, if_true_label;
{
  rtx tem;
  int dummy_true_label = 0;

  /* Reverse the comparison if that is safe and we want to jump if it is
     false.  */
  if (! if_true_label && ! FLOAT_MODE_P (mode))
    {
      if_true_label = if_false_label;
      if_false_label = 0;
      code = reverse_condition (code);
    }

  /* If one operand is constant, make it the second one.  Only do this
     if the other operand is not constant as well.  */

  if ((CONSTANT_P (op0) && ! CONSTANT_P (op1))
      || (GET_CODE (op0) == CONST_INT && GET_CODE (op1) != CONST_INT))
    {
      tem = op0;
      op0 = op1;
      op1 = tem;
      code = swap_condition (code);
    }

  if (flag_force_mem)
    {
      op0 = force_not_mem (op0);
      op1 = force_not_mem (op1);
    }

  do_pending_stack_adjust ();

  if (GET_CODE (op0) == CONST_INT && GET_CODE (op1) == CONST_INT
      && (tem = simplify_relational_operation (code, mode, op0, op1)) != 0)
    {
      if (tem == const_true_rtx)
        {
          if (if_true_label)
            emit_jump (if_true_label);
        }
      else
        {
          if (if_false_label)
            emit_jump (if_false_label);
        }
      return;
    }

#if 0
  /* There's no need to do this now that combine.c can eliminate lots of
     sign extensions.  This can be less efficient in certain cases on other
     machines.  */

  /* If this is a signed equality comparison, we can do it as an
     unsigned comparison since zero-extension is cheaper than sign
     extension and comparisons with zero are done as unsigned.  This is
     the case even on machines that can do fast sign extension, since
     zero-extension is easier to combine with other operations than
     sign-extension is.  If we are comparing against a constant, we must
     convert it to what it would look like unsigned.  */
  if ((code == EQ || code == NE) && ! unsignedp
      && GET_MODE_BITSIZE (GET_MODE (op0)) <= HOST_BITS_PER_WIDE_INT)
    {
      if (GET_CODE (op1) == CONST_INT
          && (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0))) != INTVAL (op1))
        op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (GET_MODE (op0)));
      unsignedp = 1;
    }
#endif

  if (! if_true_label)
    {
      dummy_true_label = 1;
      if_true_label = gen_label_rtx ();
    }

  emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp, align,
                           if_true_label);

  if (if_false_label)
    emit_jump (if_false_label);
  if (dummy_true_label)
    emit_label (if_true_label);
}

/* Generate code for a comparison expression EXP (including code to compute
   the values to be compared) and a conditional jump to IF_FALSE_LABEL and/or
   IF_TRUE_LABEL.  One of the labels can be NULL_RTX, in which case the
   generated code will drop through.
   SIGNED_CODE should be the rtx operation for this comparison for
   signed data; UNSIGNED_CODE, likewise for use if data is unsigned.

   We force a stack adjustment unless there are currently
   things pushed on the stack that aren't yet used.  */

static void
do_compare_and_jump (exp, signed_code, unsigned_code, if_false_label,
                     if_true_label)
     register tree exp;
     enum rtx_code signed_code, unsigned_code;
     rtx if_false_label, if_true_label;
{
  unsigned int align0, align1;
  register rtx op0, op1;
  register tree type;
  register enum machine_mode mode;
  int unsignedp;
  enum rtx_code code;

  /* Don't crash if the comparison was erroneous.  */
  op0 = expand_expr_unaligned (TREE_OPERAND (exp, 0), &align0);
  if (TREE_CODE (TREE_OPERAND (exp, 0)) == ERROR_MARK)
    return;

  op1 = expand_expr_unaligned (TREE_OPERAND (exp, 1), &align1);
  type = TREE_TYPE (TREE_OPERAND (exp, 0));
  mode = TYPE_MODE (type);
  unsignedp = TREE_UNSIGNED (type);
  code = unsignedp ? unsigned_code : signed_code;

#ifdef HAVE_canonicalize_funcptr_for_compare
  /* If function pointers need to be "canonicalized" before they can
     be reliably compared, then canonicalize them.  */
  if (HAVE_canonicalize_funcptr_for_compare
      && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
      && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
          == FUNCTION_TYPE))
    {
      rtx new_op0 = gen_reg_rtx (mode);

      emit_insn (gen_canonicalize_funcptr_for_compare (new_op0, op0));
      op0 = new_op0;
    }

  if (HAVE_canonicalize_funcptr_for_compare
      && TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
      && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
          == FUNCTION_TYPE))
    {
      rtx new_op1 = gen_reg_rtx (mode);

      emit_insn (gen_canonicalize_funcptr_for_compare (new_op1, op1));
      op1 = new_op1;
    }
#endif

  /* Do any postincrements in the expression that was tested.  */
  emit_queue ();

  do_compare_rtx_and_jump (op0, op1, code, unsignedp, mode,
                           ((mode == BLKmode)
                            ? expr_size (TREE_OPERAND (exp, 0)) : NULL_RTX),
                           MIN (align0, align1),
                           if_false_label, if_true_label);
}
\f
/* Generate code to calculate EXP using a store-flag instruction
   and return an rtx for the result.  EXP is either a comparison
   or a TRUTH_NOT_EXPR whose operand is a comparison.

   If TARGET is nonzero, store the result there if convenient.

   If ONLY_CHEAP is non-zero, only do this if it is likely to be very
   cheap.

   Return zero if there is no suitable set-flag instruction
   available on this machine.

   Once expand_expr has been called on the arguments of the comparison,
   we are committed to doing the store flag, since it is not safe to
   re-evaluate the expression.  We emit the store-flag insn by calling
   emit_store_flag, but only expand the arguments if we have a reason
   to believe that emit_store_flag will be successful.  If we think that
   it will, but it isn't, we have to simulate the store-flag with a
   set/jump/set sequence.  */

static rtx
do_store_flag (exp, target, mode, only_cheap)
     tree exp;
     rtx target;
     enum machine_mode mode;
     int only_cheap;
{
  enum rtx_code code;
  tree arg0, arg1, type;
  tree tem;
  enum machine_mode operand_mode;
  int invert = 0;
  int unsignedp;
  rtx op0, op1;
  enum insn_code icode;
  rtx subtarget = target;
  rtx result, label;

  /* If this is a TRUTH_NOT_EXPR, set a flag indicating we must invert the
     result at the end.  We can't simply invert the test since it would
     have already been inverted if it were valid.  This case occurs for
     some floating-point comparisons.  */

  if (TREE_CODE (exp) == TRUTH_NOT_EXPR)
    invert = 1, exp = TREE_OPERAND (exp, 0);

  arg0 = TREE_OPERAND (exp, 0);
  arg1 = TREE_OPERAND (exp, 1);
  type = TREE_TYPE (arg0);
  operand_mode = TYPE_MODE (type);
  unsignedp = TREE_UNSIGNED (type);

  /* We won't bother with BLKmode store-flag operations because it would mean
     passing a lot of information to emit_store_flag.  */
  if (operand_mode == BLKmode)
    return 0;

  /* We won't bother with store-flag operations involving function pointers
     when function pointers must be canonicalized before comparisons.  */
#ifdef HAVE_canonicalize_funcptr_for_compare
  if (HAVE_canonicalize_funcptr_for_compare
      && ((TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 0))) == POINTER_TYPE
           && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 0))))
               == FUNCTION_TYPE))
          || (TREE_CODE (TREE_TYPE (TREE_OPERAND (exp, 1))) == POINTER_TYPE
              && (TREE_CODE (TREE_TYPE (TREE_TYPE (TREE_OPERAND (exp, 1))))
                  == FUNCTION_TYPE))))
    return 0;
#endif

  STRIP_NOPS (arg0);
  STRIP_NOPS (arg1);

  /* Get the rtx comparison code to use.  We know that EXP is a comparison
     operation of some type.  Some comparisons against 1 and -1 can be
     converted to comparisons with zero.  Do so here so that the tests
     below will be aware that we have a comparison with zero.   These
     tests will not catch constants in the first operand, but constants
     are rarely passed as the first operand.  */

  switch (TREE_CODE (exp))
    {
    case EQ_EXPR:
      code = EQ;
      break;
    case NE_EXPR:
      code = NE;
      break;
    case LT_EXPR:
      if (integer_onep (arg1))
        arg1 = integer_zero_node, code = unsignedp ? LEU : LE;
      else
        code = unsignedp ? LTU : LT;
      break;
    case LE_EXPR:
      if (! unsignedp && integer_all_onesp (arg1))
        arg1 = integer_zero_node, code = LT;
      else
        code = unsignedp ? LEU : LE;
      break;
    case GT_EXPR:
      if (! unsignedp && integer_all_onesp (arg1))
        arg1 = integer_zero_node, code = GE;
      else
        code = unsignedp ? GTU : GT;
      break;
    case GE_EXPR:
      if (integer_onep (arg1))
        arg1 = integer_zero_node, code = unsignedp ? GTU : GT;
      else
        code = unsignedp ? GEU : GE;
      break;

    case UNORDERED_EXPR:
      code = UNORDERED;
      break;
    case ORDERED_EXPR:
      code = ORDERED;
      break;
    case UNLT_EXPR:
      code = UNLT;
      break;
    case UNLE_EXPR:
      code = UNLE;
      break;
    case UNGT_EXPR:
      code = UNGT;
      break;
    case UNGE_EXPR:
      code = UNGE;
      break;
    case UNEQ_EXPR:
      code = UNEQ;
      break;

    default:
      abort ();
    }

  /* Put a constant second.  */
  if (TREE_CODE (arg0) == REAL_CST || TREE_CODE (arg0) == INTEGER_CST)
    {
      tem = arg0; arg0 = arg1; arg1 = tem;
      code = swap_condition (code);
    }

  /* If this is an equality or inequality test of a single bit, we can
     do this by shifting the bit being tested to the low-order bit and
     masking the result with the constant 1.  If the condition was EQ,
     we xor it with 1.  This does not require an scc insn and is faster
     than an scc insn even if we have it.  */

  if ((code == NE || code == EQ)
      && TREE_CODE (arg0) == BIT_AND_EXPR && integer_zerop (arg1)
      && integer_pow2p (TREE_OPERAND (arg0, 1)))
    {
      tree inner = TREE_OPERAND (arg0, 0);
      int bitnum = tree_log2 (TREE_OPERAND (arg0, 1));
      int ops_unsignedp;

      /* If INNER is a right shift of a constant and it plus BITNUM does
         not overflow, adjust BITNUM and INNER.  */

      if (TREE_CODE (inner) == RSHIFT_EXPR
          && TREE_CODE (TREE_OPERAND (inner, 1)) == INTEGER_CST
          && TREE_INT_CST_HIGH (TREE_OPERAND (inner, 1)) == 0
          && bitnum < TYPE_PRECISION (type)
          && 0 > compare_tree_int (TREE_OPERAND (inner, 1),
                                   bitnum - TYPE_PRECISION (type)))
        {
          bitnum += TREE_INT_CST_LOW (TREE_OPERAND (inner, 1));
          inner = TREE_OPERAND (inner, 0);
        }

      /* If we are going to be able to omit the AND below, we must do our
         operations as unsigned.  If we must use the AND, we have a choice.
         Normally unsigned is faster, but for some machines signed is.  */
      ops_unsignedp = (bitnum == TYPE_PRECISION (type) - 1 ? 1
#ifdef LOAD_EXTEND_OP
                       : (LOAD_EXTEND_OP (operand_mode) == SIGN_EXTEND ? 0 : 1)
#else
                       : 1
#endif
                       );

      if (! get_subtarget (subtarget)
          || GET_MODE (subtarget) != operand_mode
          || ! safe_from_p (subtarget, inner, 1))
        subtarget = 0;

      op0 = expand_expr (inner, subtarget, VOIDmode, 0);

      if (bitnum != 0)
        op0 = expand_shift (RSHIFT_EXPR, GET_MODE (op0), op0,
                            size_int (bitnum), subtarget, ops_unsignedp);

      if (GET_MODE (op0) != mode)
        op0 = convert_to_mode (mode, op0, ops_unsignedp);

      if ((code == EQ && ! invert) || (code == NE && invert))
        op0 = expand_binop (mode, xor_optab, op0, const1_rtx, subtarget,
                            ops_unsignedp, OPTAB_LIB_WIDEN);

      /* Put the AND last so it can combine with more things.  */
      if (bitnum != TYPE_PRECISION (type) - 1)
        op0 = expand_and (op0, const1_rtx, subtarget);

      return op0;
    }

  /* Now see if we are likely to be able to do this.  Return if not.  */
  if (! can_compare_p (code, operand_mode, ccp_store_flag))
    return 0;

  icode = setcc_gen_code[(int) code];
  if (icode == CODE_FOR_nothing
      || (only_cheap && insn_data[(int) icode].operand[0].mode != mode))
    {
      /* We can only do this if it is one of the special cases that
         can be handled without an scc insn.  */
      if ((code == LT && integer_zerop (arg1))
          || (! only_cheap && code == GE && integer_zerop (arg1)))
        ;
      else if (BRANCH_COST >= 0
               && ! only_cheap && (code == NE || code == EQ)
               && TREE_CODE (type) != REAL_TYPE
               && ((abs_optab->handlers[(int) operand_mode].insn_code
                    != CODE_FOR_nothing)
                   || (ffs_optab->handlers[(int) operand_mode].insn_code
                       != CODE_FOR_nothing)))
        ;
      else
        return 0;
    }
      
  preexpand_calls (exp);
  if (! get_subtarget (target)
      || GET_MODE (subtarget) != operand_mode
      || ! safe_from_p (subtarget, arg1, 1))
    subtarget = 0;

  op0 = expand_expr (arg0, subtarget, VOIDmode, 0);
  op1 = expand_expr (arg1, NULL_RTX, VOIDmode, 0);

  if (target == 0)
    target = gen_reg_rtx (mode);

  /* Pass copies of OP0 and OP1 in case they contain a QUEUED.  This is safe
     because, if the emit_store_flag does anything it will succeed and
     OP0 and OP1 will not be used subsequently.  */

  result = emit_store_flag (target, code,
                            queued_subexp_p (op0) ? copy_rtx (op0) : op0,
                            queued_subexp_p (op1) ? copy_rtx (op1) : op1,
                            operand_mode, unsignedp, 1);

  if (result)
    {
      if (invert)
        result = expand_binop (mode, xor_optab, result, const1_rtx,
                               result, 0, OPTAB_LIB_WIDEN);
      return result;
    }

  /* If this failed, we have to do this with set/compare/jump/set code.  */
  if (GET_CODE (target) != REG
      || reg_mentioned_p (target, op0) || reg_mentioned_p (target, op1))
    target = gen_reg_rtx (GET_MODE (target));

  emit_move_insn (target, invert ? const0_rtx : const1_rtx);
  result = compare_from_rtx (op0, op1, code, unsignedp,
                             operand_mode, NULL_RTX, 0);
  if (GET_CODE (result) == CONST_INT)
    return (((result == const0_rtx && ! invert)
             || (result != const0_rtx && invert))
            ? const0_rtx : const1_rtx);

  label = gen_label_rtx ();
  if (bcc_gen_fctn[(int) code] == 0)
    abort ();

  emit_jump_insn ((*bcc_gen_fctn[(int) code]) (label));
  emit_move_insn (target, invert ? const1_rtx : const0_rtx);
  emit_label (label);

  return target;
}
\f
/* Generate a tablejump instruction (used for switch statements).  */

#ifdef HAVE_tablejump

/* INDEX is the value being switched on, with the lowest value
   in the table already subtracted.
   MODE is its expected mode (needed if INDEX is constant).
   RANGE is the length of the jump table.
   TABLE_LABEL is a CODE_LABEL rtx for the table itself.

   DEFAULT_LABEL is a CODE_LABEL rtx to jump to if the
   index value is out of range.  */

void
do_tablejump (index, mode, range, table_label, default_label)
     rtx index, range, table_label, default_label;
     enum machine_mode mode;
{
  register rtx temp, vector;

  /* Do an unsigned comparison (in the proper mode) between the index
     expression and the value which represents the length of the range.
     Since we just finished subtracting the lower bound of the range
     from the index expression, this comparison allows us to simultaneously
     check that the original index expression value is both greater than
     or equal to the minimum value of the range and less than or equal to
     the maximum value of the range.  */

  emit_cmp_and_jump_insns (index, range, GTU, NULL_RTX, mode, 1,
                           0, default_label);

  /* If index is in range, it must fit in Pmode.
     Convert to Pmode so we can index with it.  */
  if (mode != Pmode)
    index = convert_to_mode (Pmode, index, 1);

  /* Don't let a MEM slip thru, because then INDEX that comes
     out of PIC_CASE_VECTOR_ADDRESS won't be a valid address,
     and break_out_memory_refs will go to work on it and mess it up.  */
#ifdef PIC_CASE_VECTOR_ADDRESS
  if (flag_pic && GET_CODE (index) != REG)
    index = copy_to_mode_reg (Pmode, index);
#endif

  /* If flag_force_addr were to affect this address
     it could interfere with the tricky assumptions made
     about addresses that contain label-refs,
     which may be valid only very near the tablejump itself.  */
  /* ??? The only correct use of CASE_VECTOR_MODE is the one inside the
     GET_MODE_SIZE, because this indicates how large insns are.  The other
     uses should all be Pmode, because they are addresses.  This code
     could fail if addresses and insns are not the same size.  */
  index = gen_rtx_PLUS (Pmode,
                        gen_rtx_MULT (Pmode, index,
                                      GEN_INT (GET_MODE_SIZE (CASE_VECTOR_MODE))),
                        gen_rtx_LABEL_REF (Pmode, table_label));
#ifdef PIC_CASE_VECTOR_ADDRESS
  if (flag_pic)
    index = PIC_CASE_VECTOR_ADDRESS (index);
  else
#endif
    index = memory_address_noforce (CASE_VECTOR_MODE, index);
  temp = gen_reg_rtx (CASE_VECTOR_MODE);
  vector = gen_rtx_MEM (CASE_VECTOR_MODE, index);
  RTX_UNCHANGING_P (vector) = 1;
  convert_move (temp, vector, 0);

  emit_jump_insn (gen_tablejump (temp, table_label));

  /* If we are generating PIC code or if the table is PC-relative, the
     table and JUMP_INSN must be adjacent, so don't output a BARRIER.  */
  if (! CASE_VECTOR_PC_RELATIVE && ! flag_pic)
    emit_barrier ();
}

#endif /* HAVE_tablejump */