gcc/cp/expr.c

   1 /* Convert language-specific tree expression to rtl instructions,
   2    for GNU compiler.
   3    Copyright (C) 1988, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22
  23 #include "config.h"
  24 #include "rtl.h"
  25 #include "tree.h"
  26 #include "flags.h"
  27 #include "expr.h"
  28 #include "cp-tree.h"
  29
  30 #undef NULL
  31 #define NULL 0
  32
  33 /* Hook used by expand_expr to expand language-specific tree codes.  */
  34
  35 rtx
  36 cplus_expand_expr (exp, target, tmode, modifier)
  37      tree exp;
  38      rtx target;
  39      enum machine_mode tmode;
  40      enum expand_modifier modifier;
  41 {
  42   tree type = TREE_TYPE (exp);
  43   register enum machine_mode mode = TYPE_MODE (type);
  44   register enum tree_code code = TREE_CODE (exp);
  45   rtx original_target = target;
  46   int ignore = target == const0_rtx;
  47
  48   if (ignore)
  49     target = 0, original_target = 0;
  50
  51   /* No sense saving up arithmetic to be done
  52      if it's all in the wrong mode to form part of an address.
  53      And force_operand won't know whether to sign-extend or zero-extend.  */
  54
  55   if (mode != Pmode && modifier == EXPAND_SUM)
  56     modifier = EXPAND_NORMAL;
  57
  58   switch (code)
  59     {
  60     case NEW_EXPR:
  61       {
  62         /* Something needs to be initialized, but we didn't know
  63            where that thing was when building the tree.  For example,
  64            it could be the return value of a function, or a parameter
  65            to a function which lays down in the stack, or a temporary
  66            variable which must be passed by reference.
  67
  68            Cleanups are handled in a language-specific way: they
  69            might be run by the called function (true in GNU C++
  70            for parameters with cleanups), or they might be
  71            run by the caller, after the call (true in GNU C++
  72            for other cleanup needs).  */
  73
  74         tree func = TREE_OPERAND (exp, 0);
  75         tree args = TREE_OPERAND (exp, 1);
  76         tree type = TREE_TYPE (exp), slot;
  77         tree fn_type = TREE_TYPE (TREE_TYPE (func));
  78         tree return_type = TREE_TYPE (fn_type);
  79         tree call_exp;
  80         rtx call_target, return_target;
  81         int pcc_struct_return = 0;
  82
  83         /* The expression `init' wants to initialize what
  84            `target' represents.  SLOT holds the slot for TARGET.  */
  85         slot = TREE_OPERAND (exp, 2);
  86
  87         if (target == 0)
  88           {
  89             /* Should always be called with a target in BLKmode case.  */
  90             my_friendly_assert (mode != BLKmode, 205);
  91             my_friendly_assert (DECL_RTL (slot) != 0, 206);
  92
  93             target = gen_reg_rtx (mode);
  94           }
  95
  96         /* The target the initializer will initialize (CALL_TARGET)
  97            must now be directed to initialize the target we are
  98            supposed to initialize (TARGET).  The semantics for
  99            choosing what CALL_TARGET is is language-specific,
 100            as is building the call which will perform the
 101            initialization.  It is left here to show the choices that
 102            exist for C++.  */
 103
 104         if (TREE_CODE (func) == ADDR_EXPR
 105             && TREE_CODE (TREE_OPERAND (func, 0)) == FUNCTION_DECL
 106             && DECL_CONSTRUCTOR_P (TREE_OPERAND (func, 0)))
 107           {
 108             type = build_pointer_type (type);
 109             /* Don't clobber a value that might be part of a default
 110                parameter value.  */
 111             mark_addressable (slot);
 112             if (TREE_PERMANENT (args))
 113               args = tree_cons (0, build1 (ADDR_EXPR, type, slot),
 114                                 TREE_CHAIN (args));
 115             else
 116               TREE_VALUE (args) = build1 (ADDR_EXPR, type, slot);
 117             call_target = 0;
 118           }
 119         else if (TREE_CODE (return_type) == REFERENCE_TYPE)
 120           {
 121             type = return_type;
 122             call_target = 0;
 123           }
 124         else
 125           {
 126 #ifdef PCC_STATIC_STRUCT_RETURN
 127             pcc_struct_return = 1;
 128             call_target = 0;
 129 #else
 130             call_target = target;
 131 #endif
 132           }
 133         if (call_target)
 134           {
 135             /* Make this a valid memory address now.  The code below assumes
 136                that it can compare rtx and make assumptions based on the
 137                result.  The assumptions are true only if the address was
 138                valid to begin with.  */
 139             call_target = validize_mem (call_target);
 140           }
 141
 142         call_exp = build (CALL_EXPR, type, func, args, 0);
 143         TREE_SIDE_EFFECTS (call_exp) = 1;
 144         return_target = expand_call (call_exp, call_target, ignore);
 145         if (call_target == 0)
 146           {
 147             if (pcc_struct_return)
 148               {
 149                 extern int flag_access_control;
 150                 int old_ac = flag_access_control;
 151
 152                 tree init = build_decl (VAR_DECL, 0, type);
 153                 TREE_ADDRESSABLE (init) = 1;
 154                 DECL_RTL (init) = return_target;
 155
 156                 flag_access_control = 0;
 157                 expand_aggr_init (slot, init, 0, LOOKUP_ONLYCONVERTING);
 158                 flag_access_control = old_ac;
 159
 160                 if (TYPE_NEEDS_DESTRUCTOR (type))
 161                   {
 162                     init = build_decl (VAR_DECL, 0,
 163                                        build_reference_type (type));
 164                     DECL_RTL (init) = XEXP (return_target, 0);
 165
 166                     init = maybe_build_cleanup (convert_from_reference (init));
 167                     if (init != NULL_TREE)
 168                       expand_expr (init, 0, 0, 0);
 169                   }
 170                 call_target = return_target = DECL_RTL (slot);
 171               }
 172             else
 173               call_target = return_target;
 174           }
 175
 176         if (call_target != return_target)
 177           {
 178             my_friendly_assert (TYPE_HAS_TRIVIAL_INIT_REF (type), 317);
 179             if (GET_MODE (return_target) == BLKmode)
 180               emit_block_move (call_target, return_target, expr_size (exp),
 181                                TYPE_ALIGN (type) / BITS_PER_UNIT);
 182             else
 183               emit_move_insn (call_target, return_target);
 184           }
 185
 186         if (TREE_CODE (return_type) == REFERENCE_TYPE)
 187           {
 188             tree init;
 189
 190             if (GET_CODE (call_target) == REG
 191                 && REGNO (call_target) < FIRST_PSEUDO_REGISTER)
 192               my_friendly_abort (39);
 193
 194             type = TREE_TYPE (exp);
 195
 196             init = build (RTL_EXPR, return_type, 0, call_target);
 197             /* We got back a reference to the type we want.  Now initialize
 198                target with that.  */
 199             expand_aggr_init (slot, init, 0, LOOKUP_ONLYCONVERTING);
 200           }
 201
 202         if (DECL_RTL (slot) != target)
 203           emit_move_insn (DECL_RTL (slot), target);
 204         return DECL_RTL (slot);
 205       }
 206
 207     case OFFSET_REF:
 208       {
 209 #if 1
 210         return expand_expr (default_conversion (resolve_offset_ref (exp)),
 211                             target, tmode, EXPAND_NORMAL);
 212 #else
 213         /* This is old crusty code, and does not handle all that the
 214            resolve_offset_ref function does.  (mrs) */
 215         tree base = build_unary_op (ADDR_EXPR, TREE_OPERAND (exp, 0), 0);
 216         tree offset = build_unary_op (ADDR_EXPR, TREE_OPERAND (exp, 1), 0);
 217         return expand_expr (build (PLUS_EXPR, TREE_TYPE (exp), base, offset),
 218                             target, tmode, EXPAND_NORMAL);
 219 #endif
 220       }
 221
 222     case THUNK_DECL:
 223       return DECL_RTL (exp);
 224
 225     case THROW_EXPR:
 226       expand_throw (TREE_OPERAND (exp, 0));
 227       return NULL;
 228
 229     case UNSAVE_EXPR:
 230       {
 231         rtx temp;
 232         temp = expand_expr (TREE_OPERAND (exp, 0), target, tmode, modifier);
 233         TREE_OPERAND (exp, 0) = unsave_expr_now (TREE_OPERAND (exp, 0));
 234         return temp;
 235       }
 236
 237     default:
 238       break;
 239     }
 240   my_friendly_abort (40);
 241   /* NOTREACHED */
 242   return NULL;
 243 }
 244
 245 void
 246 init_cplus_expand ()
 247 {
 248   lang_expand_expr = cplus_expand_expr;
 249 }
 250
 251 /* If DECL had its rtl moved from where callers expect it
 252    to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
 253    which may be a pseudo instead of a hard register.  */
 254
 255 void
 256 fixup_result_decl (decl, result)
 257      tree decl;
 258      rtx result;
 259 {
 260   if (REG_P (result))
 261     {
 262       if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
 263         {
 264           rtx real_decl_result;
 265
 266 #ifdef FUNCTION_OUTGOING_VALUE
 267           real_decl_result
 268             = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
 269 #else
 270           real_decl_result
 271             = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
 272 #endif
 273           REG_FUNCTION_VALUE_P (real_decl_result) = 1;
 274           result = real_decl_result;
 275         }
 276       store_expr (decl, result, 0);
 277       emit_insn (gen_rtx (USE, VOIDmode, result));
 278     }
 279 }
 280
 281 /* Expand this initialization inline and see if it's simple enough that
 282    it can be done at compile-time.  */
 283
 284 static tree
 285 extract_aggr_init (decl, init)
 286      tree decl, init;
 287 {
 288   return 0;
 289 }
 290
 291 static tree
 292 extract_scalar_init (decl, init)
 293      tree decl, init;
 294 {
 295   rtx value, insns, insn;
 296   extern struct obstack temporary_obstack;
 297   tree t = NULL_TREE;
 298
 299   push_obstacks (&temporary_obstack, &temporary_obstack);
 300   start_sequence ();
 301   value = expand_expr (init, NULL_RTX, VOIDmode, 0);
 302   insns = get_insns ();
 303   end_sequence ();
 304   reg_scan (insns, max_reg_num (), 0);
 305   jump_optimize (insns, 0, 0, 1);
 306   pop_obstacks ();
 307
 308   for (insn = insns; insn; insn = NEXT_INSN (insn))
 309     {
 310       rtx r, to;
 311
 312       if (GET_CODE (insn) == NOTE)
 313         continue;
 314       else if (GET_CODE (insn) != INSN)
 315         return 0;
 316
 317       r = PATTERN (insn);
 318       if (GET_CODE (r) != SET)
 319         return 0;
 320
 321       to = XEXP (r, 0);
 322
 323       if (! (to == value ||
 324              (GET_CODE (to) == SUBREG && XEXP (to, 0) == value)))
 325         return 0;
 326
 327       r = XEXP (r, 1);
 328
 329       switch (GET_CODE (r))
 330         {
 331         case CONST_INT:
 332           t = build_int_2 (XEXP (r, 0), 0);
 333           break;
 334         default:
 335           return 0;
 336         }
 337     }
 338
 339   return t;
 340 }
 341
 342 int
 343 extract_init (decl, init)
 344      tree decl, init;
 345 {
 346   return 0;
 347
 348 #if 0
 349   if (IS_AGGR_TYPE (TREE_TYPE (decl))
 350       || TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
 351     init = extract_aggr_init (decl, init);
 352   else
 353     init = extract_scalar_init (decl, init);
 354
 355   if (init == NULL_TREE)
 356     return 0;
 357
 358   DECL_INITIAL (decl) = init;
 359   return 1;
 360 #endif
 361 }
 362
 363 void
 364 do_case (start, end)
 365      tree start, end;
 366 {
 367   tree value1 = NULL_TREE, value2 = NULL_TREE, label;
 368
 369   if (end && pedantic)
 370     pedwarn ("ANSI C++ forbids range expressions in switch statement");
 371
 372   if (current_template_parms)
 373     {
 374       add_tree (build_min_nt (CASE_LABEL, start, end));
 375       return;
 376     }
 377
 378   if (start)
 379     value1 = check_cp_case_value (start);
 380   if (end)
 381     value2 = check_cp_case_value (end);
 382
 383   label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
 384
 385   if (value1 != error_mark_node
 386       && value2 != error_mark_node)
 387     {
 388       tree duplicate;
 389       int success;
 390
 391       if (end)
 392         success = pushcase_range (value1, value2, convert_and_check,
 393                                   label, &duplicate);
 394       else if (start)
 395         success = pushcase (value1, convert_and_check, label, &duplicate);
 396       else
 397         success = pushcase (NULL_TREE, 0, label, &duplicate);
 398
 399       if (success == 1)
 400         {
 401           if (end)
 402             error ("case label not within a switch statement");
 403           else if (start)
 404             cp_error ("case label `%E' not within a switch statement", start);
 405           else
 406             error ("default label not within a switch statement");
 407         }
 408       else if (success == 2)
 409         {
 410           if (end)
 411             {
 412               error ("duplicate (or overlapping) case value");
 413               cp_error_at ("this is the first entry overlapping that value",
 414                            duplicate);
 415             }
 416           else if (start)
 417             {
 418               cp_error ("duplicate case value `%E'", start);
 419               cp_error_at ("previously used here", duplicate);
 420             }
 421           else
 422             {
 423               error ("multiple default labels in one switch");
 424               cp_error_at ("this is the first default label", duplicate);
 425             }
 426         }
 427       else if (success == 3)
 428         warning ("case value out of range");
 429       else if (success == 4)
 430         warning ("empty range specified");
 431       else if (success == 5)
 432         {
 433           if (end)
 434             error ("case label within scope of cleanup or variable array");
 435           else
 436             cp_error ("case label `%E' within scope of cleanup or variable array", start);
 437         }
 438     }
 439   if (start)
 440     define_case_label (label);
 441   else
 442     define_case_label (NULL_TREE);
 443 }