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 "system.h"
  25 #include "rtl.h"
  26 #include "tree.h"
  27 #include "flags.h"
  28 #include "expr.h"
  29 #include "cp-tree.h"
  30 #include "toplev.h"
  31
  32 #if 0
  33 static tree extract_aggr_init PROTO((tree, tree));
  34 static tree extract_scalar_init PROTO((tree, tree));
  35 #endif
  36 static rtx cplus_expand_expr PROTO((tree, rtx, enum machine_mode,
  37                                     enum expand_modifier));
  38
  39 /* Hook used by expand_expr to expand language-specific tree codes.  */
  40
  41 static rtx
  42 cplus_expand_expr (exp, target, tmode, modifier)
  43      tree exp;
  44      rtx target;
  45      enum machine_mode tmode;
  46      enum expand_modifier modifier;
  47 {
  48   tree type = TREE_TYPE (exp);
  49   register enum machine_mode mode = TYPE_MODE (type);
  50   register enum tree_code code = TREE_CODE (exp);
  51   int ignore = target == const0_rtx;
  52
  53   if (ignore)
  54     target = 0;
  55
  56   /* No sense saving up arithmetic to be done
  57      if it's all in the wrong mode to form part of an address.
  58      And force_operand won't know whether to sign-extend or zero-extend.  */
  59
  60   if (mode != Pmode && modifier == EXPAND_SUM)
  61     modifier = EXPAND_NORMAL;
  62
  63   switch (code)
  64     {
  65     case AGGR_INIT_EXPR:
  66       {
  67         /* Something needs to be initialized, but we didn't know
  68            where that thing was when building the tree.  For example,
  69            it could be the return value of a function, or a parameter
  70            to a function which lays down in the stack, or a temporary
  71            variable which must be passed by reference.
  72
  73            Cleanups are handled in a language-specific way: they
  74            might be run by the called function (true in GNU C++
  75            for parameters with cleanups), or they might be
  76            run by the caller, after the call (true in GNU C++
  77            for other cleanup needs).  */
  78
  79         tree func = TREE_OPERAND (exp, 0);
  80         tree args = TREE_OPERAND (exp, 1);
  81         tree type = TREE_TYPE (exp), slot;
  82         tree call_exp;
  83         rtx call_target, return_target;
  84         int pcc_struct_return = 0;
  85
  86         /* The expression `init' wants to initialize what
  87            `target' represents.  SLOT holds the slot for TARGET.  */
  88         slot = TREE_OPERAND (exp, 2);
  89
  90         /* Should always be called with a target.  */
  91         my_friendly_assert (target != NULL_RTX, 205);
  92
  93         /* The target the initializer will initialize (CALL_TARGET)
  94            must now be directed to initialize the target we are
  95            supposed to initialize (TARGET).  The semantics for
  96            choosing what CALL_TARGET is is language-specific,
  97            as is building the call which will perform the
  98            initialization.  It is left here to show the choices that
  99            exist for C++.  */
 100
 101         if (TREE_CODE (func) == ADDR_EXPR
 102             && TREE_CODE (TREE_OPERAND (func, 0)) == FUNCTION_DECL
 103             && DECL_CONSTRUCTOR_P (TREE_OPERAND (func, 0)))
 104           {
 105             type = build_pointer_type (type);
 106             /* Don't clobber a value that might be part of a default
 107                parameter value.  */
 108             mark_addressable (slot);
 109             if (TREE_PERMANENT (args))
 110               args = expr_tree_cons (0, build1 (ADDR_EXPR, type, slot),
 111                                 TREE_CHAIN (args));
 112             else
 113               TREE_VALUE (args) = build1 (ADDR_EXPR, type, slot);
 114             call_target = 0;
 115           }
 116         else
 117           {
 118             call_target = target;
 119 #ifdef PCC_STATIC_STRUCT_RETURN
 120             if (aggregate_value_p (type))
 121               {
 122                 pcc_struct_return = 1;
 123                 call_target = 0;
 124               }
 125 #endif
 126           }
 127
 128         call_exp = build (CALL_EXPR, type, func, args, NULL_TREE);
 129         TREE_SIDE_EFFECTS (call_exp) = 1;
 130         return_target = expand_call (call_exp, call_target, ignore);
 131
 132         if (call_target)
 133           /* Trust that the right thing has been done; it's too hard to
 134              verify.  */
 135           return return_target;
 136
 137         /* If we're suffering under the ancient PCC_STATIC_STRUCT_RETURN
 138            calling convention, we need to copy the return value out of
 139            the static return buffer into slot.  */
 140         if (pcc_struct_return)
 141           {
 142             extern int flag_access_control;
 143             int old_ac = flag_access_control;
 144
 145             tree init = build_decl (VAR_DECL, NULL_TREE,
 146                                     build_reference_type (type));
 147             DECL_RTL (init) = XEXP (return_target, 0);
 148             init = convert_from_reference (init);
 149
 150             flag_access_control = 0;
 151             expand_aggr_init (slot, init, LOOKUP_ONLYCONVERTING);
 152             flag_access_control = old_ac;
 153
 154             if (TYPE_NEEDS_DESTRUCTOR (type))
 155               {
 156                 init = maybe_build_cleanup (init);
 157                 if (init != NULL_TREE)
 158                   expand_expr (init, const0_rtx, VOIDmode, 0);
 159               }
 160           }
 161
 162         return DECL_RTL (slot);
 163       }
 164
 165     case PTRMEM_CST:
 166       {
 167         tree member;
 168         tree offset;
 169
 170         /* Find the member.  */
 171         member = PTRMEM_CST_MEMBER (exp);
 172
 173         if (TREE_CODE (member) == FIELD_DECL)
 174           {
 175             /* Find the offset for the field.  */
 176             offset = convert (sizetype,
 177                               size_binop (EASY_DIV_EXPR,
 178                                           DECL_FIELD_BITPOS (member),
 179                                           size_int (BITS_PER_UNIT)));
 180
 181             /* We offset all pointer to data members by 1 so that we
 182                can distinguish between a null pointer to data member
 183                and the first data member of a structure.  */
 184             offset = size_binop (PLUS_EXPR, offset, size_int (1));
 185
 186             return expand_expr (cp_convert (type, offset), target, tmode,
 187                                 modifier);
 188           }
 189         else
 190           {
 191             /* We don't yet handle pointer-to-member functions this
 192                way.  */
 193             my_friendly_abort (0);
 194             return 0;
 195           }
 196       }
 197
 198     case OFFSET_REF:
 199       {
 200         return expand_expr (default_conversion (resolve_offset_ref (exp)),
 201                             target, tmode, EXPAND_NORMAL);
 202       }
 203
 204     case THUNK_DECL:
 205       return DECL_RTL (exp);
 206
 207     case THROW_EXPR:
 208       expand_throw (TREE_OPERAND (exp, 0));
 209       return NULL;
 210
 211     case VEC_INIT_EXPR:
 212       return expand_expr
 213         (expand_vec_init
 214          (NULL_TREE, TREE_OPERAND (exp, 0),
 215           build_binary_op (MINUS_EXPR, TREE_OPERAND (exp, 2),
 216                            integer_one_node, 1),
 217           TREE_OPERAND (exp, 1), 0), target, tmode, modifier);
 218
 219     case NEW_EXPR:
 220       return expand_expr (build_new_1 (exp), target, tmode, modifier);
 221
 222     default:
 223       break;
 224     }
 225   my_friendly_abort (40);
 226   /* NOTREACHED */
 227   return NULL;
 228 }
 229
 230 void
 231 init_cplus_expand ()
 232 {
 233   lang_expand_expr = cplus_expand_expr;
 234 }
 235
 236 /* If DECL had its rtl moved from where callers expect it
 237    to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
 238    which may be a pseudo instead of a hard register.  */
 239
 240 void
 241 fixup_result_decl (decl, result)
 242      tree decl;
 243      rtx result;
 244 {
 245   if (REG_P (result))
 246     {
 247       if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
 248         {
 249           rtx real_decl_result;
 250
 251 #ifdef FUNCTION_OUTGOING_VALUE
 252           real_decl_result
 253             = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
 254 #else
 255           real_decl_result
 256             = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
 257 #endif
 258           REG_FUNCTION_VALUE_P (real_decl_result) = 1;
 259           result = real_decl_result;
 260         }
 261       store_expr (decl, result, 0);
 262       emit_insn (gen_rtx (USE, VOIDmode, result));
 263     }
 264 }
 265
 266 #if 0
 267 /* Expand this initialization inline and see if it's simple enough that
 268    it can be done at compile-time.  */
 269
 270 static tree
 271 extract_aggr_init (decl, init)
 272      tree decl, init;
 273 {
 274   return 0;
 275 }
 276
 277 static tree
 278 extract_scalar_init (decl, init)
 279      tree decl, init;
 280 {
 281   rtx value, insns, insn;
 282   extern struct obstack temporary_obstack;
 283   tree t = NULL_TREE;
 284
 285   push_obstacks (&temporary_obstack, &temporary_obstack);
 286   start_sequence ();
 287   value = expand_expr (init, NULL_RTX, VOIDmode, 0);
 288   insns = get_insns ();
 289   end_sequence ();
 290   reg_scan (insns, max_reg_num (), 0);
 291   jump_optimize (insns, 0, 0, 1);
 292   pop_obstacks ();
 293
 294   for (insn = insns; insn; insn = NEXT_INSN (insn))
 295     {
 296       rtx r, to;
 297
 298       if (GET_CODE (insn) == NOTE)
 299         continue;
 300       else if (GET_CODE (insn) != INSN)
 301         return 0;
 302
 303       r = PATTERN (insn);
 304       if (GET_CODE (r) != SET)
 305         return 0;
 306
 307       to = XEXP (r, 0);
 308
 309       if (! (to == value
 310              || (GET_CODE (to) == SUBREG && XEXP (to, 0) == value)))
 311         return 0;
 312
 313       r = XEXP (r, 1);
 314
 315       switch (GET_CODE (r))
 316         {
 317         case CONST_INT:
 318           t = build_int_2 (XEXP (r, 0), 0);
 319           break;
 320         default:
 321           return 0;
 322         }
 323     }
 324
 325   return t;
 326 }
 327 #endif
 328
 329 int
 330 extract_init (decl, init)
 331      tree decl ATTRIBUTE_UNUSED, init ATTRIBUTE_UNUSED;
 332 {
 333   return 0;
 334
 335 #if 0
 336   if (IS_AGGR_TYPE (TREE_TYPE (decl))
 337       || TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
 338     init = extract_aggr_init (decl, init);
 339   else
 340     init = extract_scalar_init (decl, init);
 341
 342   if (init == NULL_TREE)
 343     return 0;
 344
 345   DECL_INITIAL (decl) = init;
 346   return 1;
 347 #endif
 348 }
 349
 350 void
 351 do_case (start, end)
 352      tree start, end;
 353 {
 354   tree value1 = NULL_TREE, value2 = NULL_TREE, label;
 355
 356   if (start != NULL_TREE && TREE_TYPE (start) != NULL_TREE
 357       && POINTER_TYPE_P (TREE_TYPE (start)))
 358     error ("pointers are not permitted as case values");
 359
 360   if (end && pedantic)
 361     pedwarn ("ANSI C++ forbids range expressions in switch statement");
 362
 363   if (processing_template_decl)
 364     {
 365       add_tree (build_min_nt (CASE_LABEL, start, end));
 366       return;
 367     }
 368
 369   if (start)
 370     value1 = check_cp_case_value (start);
 371   if (end)
 372     value2 = check_cp_case_value (end);
 373
 374   label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
 375
 376   if (value1 != error_mark_node
 377       && value2 != error_mark_node)
 378     {
 379       tree duplicate;
 380       int success;
 381
 382       if (end)
 383         success = pushcase_range (value1, value2, convert_and_check,
 384                                   label, &duplicate);
 385       else if (start)
 386         success = pushcase (value1, convert_and_check, label, &duplicate);
 387       else
 388         success = pushcase (NULL_TREE, 0, label, &duplicate);
 389
 390       if (success == 1)
 391         {
 392           if (end)
 393             error ("case label not within a switch statement");
 394           else if (start)
 395             cp_error ("case label `%E' not within a switch statement", start);
 396           else
 397             error ("default label not within a switch statement");
 398         }
 399       else if (success == 2)
 400         {
 401           if (end)
 402             {
 403               error ("duplicate (or overlapping) case value");
 404               cp_error_at ("this is the first entry overlapping that value",
 405                            duplicate);
 406             }
 407           else if (start)
 408             {
 409               cp_error ("duplicate case value `%E'", start);
 410               cp_error_at ("previously used here", duplicate);
 411             }
 412           else
 413             {
 414               error ("multiple default labels in one switch");
 415               cp_error_at ("this is the first default label", duplicate);
 416             }
 417         }
 418       else if (success == 3)
 419         warning ("case value out of range");
 420       else if (success == 4)
 421         warning ("empty range specified");
 422       else if (success == 5)
 423         {
 424           if (end)
 425             error ("case label within scope of cleanup or variable array");
 426           else if (! start)
 427             error ("`default' label within scope of cleanup or variable array");
 428           else
 429             cp_error ("case label `%E' within scope of cleanup or variable array", start);
 430         }
 431     }
 432   define_case_label ();
 433 }