gcc/cp/expr.c

   1 /* Convert language-specific tree expression to rtl instructions,
   2    for GNU compiler.
   3    Copyright (C) 1988, 92-97, 1998 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 output_constant to expand language-specific
  40    constants.  */
  41
  42 tree
  43 cplus_expand_constant (cst)
  44      tree cst;
  45 {
  46   switch (TREE_CODE (cst))
  47     {
  48     case PTRMEM_CST:
  49       {
  50         tree type = TREE_TYPE (cst);
  51         tree member;
  52         tree offset;
  53
  54         /* Find the member.  */
  55         member = PTRMEM_CST_MEMBER (cst);
  56
  57         if (TREE_CODE (member) == FIELD_DECL)
  58           {
  59             /* Find the offset for the field.  */
  60             offset = convert (sizetype,
  61                               size_binop (EASY_DIV_EXPR,
  62                                           DECL_FIELD_BITPOS (member),
  63                                           size_int (BITS_PER_UNIT)));
  64
  65             /* We offset all pointer to data members by 1 so that we
  66                can distinguish between a null pointer to data member
  67                and the first data member of a structure.  */
  68             offset = size_binop (PLUS_EXPR, offset, size_int (1));
  69
  70             cst = cp_convert (type, offset);
  71           }
  72         else
  73           {
  74             tree delta;
  75             tree idx;
  76             tree pfn;
  77             tree delta2;
  78
  79             expand_ptrmemfunc_cst (cst, &delta, &idx, &pfn, &delta2);
  80
  81             cst = build_ptrmemfunc1 (type, delta, idx,
  82                                      pfn, delta2);
  83           }
  84       }
  85       break;
  86
  87     default:
  88       /* There's nothing to do.  */
  89       break;
  90     }
  91
  92   return cst;
  93 }
  94
  95 /* Hook used by expand_expr to expand language-specific tree codes.  */
  96
  97 static rtx
  98 cplus_expand_expr (exp, target, tmode, modifier)
  99      tree exp;
 100      rtx target;
 101      enum machine_mode tmode;
 102      enum expand_modifier modifier;
 103 {
 104   tree type = TREE_TYPE (exp);
 105   register enum machine_mode mode = TYPE_MODE (type);
 106   register enum tree_code code = TREE_CODE (exp);
 107   int ignore = target == const0_rtx;
 108
 109   if (ignore)
 110     target = 0;
 111
 112   /* No sense saving up arithmetic to be done
 113      if it's all in the wrong mode to form part of an address.
 114      And force_operand won't know whether to sign-extend or zero-extend.  */
 115
 116   if (mode != Pmode && modifier == EXPAND_SUM)
 117     modifier = EXPAND_NORMAL;
 118
 119   switch (code)
 120     {
 121     case AGGR_INIT_EXPR:
 122       {
 123         /* Something needs to be initialized, but we didn't know
 124            where that thing was when building the tree.  For example,
 125            it could be the return value of a function, or a parameter
 126            to a function which lays down in the stack, or a temporary
 127            variable which must be passed by reference.
 128
 129            Cleanups are handled in a language-specific way: they
 130            might be run by the called function (true in GNU C++
 131            for parameters with cleanups), or they might be
 132            run by the caller, after the call (true in GNU C++
 133            for other cleanup needs).  */
 134
 135         tree func = TREE_OPERAND (exp, 0);
 136         tree args = TREE_OPERAND (exp, 1);
 137         tree type = TREE_TYPE (exp), slot;
 138         tree call_exp;
 139         rtx call_target, return_target;
 140         int pcc_struct_return = 0;
 141
 142         /* The expression `init' wants to initialize what
 143            `target' represents.  SLOT holds the slot for TARGET.  */
 144         slot = TREE_OPERAND (exp, 2);
 145
 146         /* Should always be called with a target.  */
 147         my_friendly_assert (target != NULL_RTX, 205);
 148
 149         /* The target the initializer will initialize (CALL_TARGET)
 150            must now be directed to initialize the target we are
 151            supposed to initialize (TARGET).  The semantics for
 152            choosing what CALL_TARGET is is language-specific,
 153            as is building the call which will perform the
 154            initialization.  It is left here to show the choices that
 155            exist for C++.  */
 156
 157         if (AGGR_INIT_VIA_CTOR_P (exp))
 158           {
 159             type = build_pointer_type (type);
 160             /* Don't clobber a value that might be part of a default
 161                parameter value.  */
 162             mark_addressable (slot);
 163             if (TREE_PERMANENT (args))
 164               args = expr_tree_cons (0, build1 (ADDR_EXPR, type, slot),
 165                                 TREE_CHAIN (args));
 166             else
 167               TREE_VALUE (args) = build1 (ADDR_EXPR, type, slot);
 168             call_target = 0;
 169           }
 170         else
 171           {
 172             call_target = target;
 173 #ifdef PCC_STATIC_STRUCT_RETURN
 174             if (aggregate_value_p (type))
 175               {
 176                 pcc_struct_return = 1;
 177                 call_target = 0;
 178               }
 179 #endif
 180           }
 181
 182         call_exp = build (CALL_EXPR, type, func, args, NULL_TREE);
 183         TREE_SIDE_EFFECTS (call_exp) = 1;
 184         return_target = expand_call (call_exp, call_target, ignore);
 185
 186         if (call_target)
 187           /* Trust that the right thing has been done; it's too hard to
 188              verify.  */
 189           return return_target;
 190
 191         /* If we're suffering under the ancient PCC_STATIC_STRUCT_RETURN
 192            calling convention, we need to copy the return value out of
 193            the static return buffer into slot.  */
 194         if (pcc_struct_return)
 195           {
 196             extern int flag_access_control;
 197             int old_ac = flag_access_control;
 198
 199             tree init = build_decl (VAR_DECL, NULL_TREE,
 200                                     build_reference_type (type));
 201             DECL_RTL (init) = XEXP (return_target, 0);
 202             init = convert_from_reference (init);
 203
 204             flag_access_control = 0;
 205             expand_expr (build_aggr_init (slot, init,
 206                                           LOOKUP_ONLYCONVERTING),
 207                          target, tmode, EXPAND_NORMAL);
 208             flag_access_control = old_ac;
 209
 210             if (TYPE_NEEDS_DESTRUCTOR (type))
 211               {
 212                 init = maybe_build_cleanup (init);
 213                 if (init != NULL_TREE)
 214                   expand_expr (init, const0_rtx, VOIDmode, 0);
 215               }
 216           }
 217
 218         return DECL_RTL (slot);
 219       }
 220
 221     case PTRMEM_CST:
 222       return expand_expr (cplus_expand_constant (exp),
 223                           target, tmode, modifier);
 224
 225     case OFFSET_REF:
 226       {
 227         return expand_expr (default_conversion (resolve_offset_ref (exp)),
 228                             target, tmode, EXPAND_NORMAL);
 229       }
 230
 231     case THUNK_DECL:
 232       return DECL_RTL (exp);
 233
 234     case THROW_EXPR:
 235       expand_throw (TREE_OPERAND (exp, 0));
 236       return NULL;
 237
 238     case VEC_INIT_EXPR:
 239       return expand_expr
 240         (build_vec_init
 241          (NULL_TREE, TREE_OPERAND (exp, 0),
 242           build_binary_op (MINUS_EXPR, TREE_OPERAND (exp, 2),
 243                            integer_one_node),
 244           TREE_OPERAND (exp, 1), 0), target, tmode, modifier);
 245
 246     case NEW_EXPR:
 247       return expand_expr (build_new_1 (exp), target, tmode, modifier);
 248
 249     case STMT_EXPR:
 250       {
 251         tree rtl_expr = begin_stmt_expr ();
 252         tree block = expand_stmt (STMT_EXPR_STMT (exp));
 253         finish_stmt_expr (rtl_expr, block);
 254         return expand_expr (rtl_expr, target, tmode, modifier);
 255       }
 256       break;
 257
 258     default:
 259       break;
 260     }
 261   my_friendly_abort (40);
 262   /* NOTREACHED */
 263   return NULL;
 264 }
 265
 266 void
 267 init_cplus_expand ()
 268 {
 269   lang_expand_expr = cplus_expand_expr;
 270   lang_expand_constant = cplus_expand_constant;
 271 }
 272
 273 /* If DECL had its rtl moved from where callers expect it
 274    to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
 275    which may be a pseudo instead of a hard register.  */
 276
 277 void
 278 fixup_result_decl (decl, result)
 279      tree decl;
 280      rtx result;
 281 {
 282   if (REG_P (result))
 283     {
 284       if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
 285         {
 286           rtx real_decl_result;
 287
 288 #ifdef FUNCTION_OUTGOING_VALUE
 289           real_decl_result
 290             = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
 291 #else
 292           real_decl_result
 293             = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
 294 #endif
 295           REG_FUNCTION_VALUE_P (real_decl_result) = 1;
 296           result = real_decl_result;
 297         }
 298       store_expr (decl, result, 0);
 299       emit_insn (gen_rtx (USE, VOIDmode, result));
 300     }
 301 }
 302
 303 #if 0
 304 /* Expand this initialization inline and see if it's simple enough that
 305    it can be done at compile-time.  */
 306
 307 static tree
 308 extract_aggr_init (decl, init)
 309      tree decl, init;
 310 {
 311   return 0;
 312 }
 313
 314 static tree
 315 extract_scalar_init (decl, init)
 316      tree decl, init;
 317 {
 318   rtx value, insns, insn;
 319   extern struct obstack temporary_obstack;
 320   tree t = NULL_TREE;
 321
 322   push_obstacks (&temporary_obstack, &temporary_obstack);
 323   start_sequence ();
 324   value = expand_expr (init, NULL_RTX, VOIDmode, 0);
 325   insns = get_insns ();
 326   end_sequence ();
 327   reg_scan (insns, max_reg_num (), 0);
 328   jump_optimize (insns, 0, 0, 1);
 329   pop_obstacks ();
 330
 331   for (insn = insns; insn; insn = NEXT_INSN (insn))
 332     {
 333       rtx r, to;
 334
 335       if (GET_CODE (insn) == NOTE)
 336         continue;
 337       else if (GET_CODE (insn) != INSN)
 338         return 0;
 339
 340       r = PATTERN (insn);
 341       if (GET_CODE (r) != SET)
 342         return 0;
 343
 344       to = XEXP (r, 0);
 345
 346       if (! (to == value
 347              || (GET_CODE (to) == SUBREG && XEXP (to, 0) == value)))
 348         return 0;
 349
 350       r = XEXP (r, 1);
 351
 352       switch (GET_CODE (r))
 353         {
 354         case CONST_INT:
 355           t = build_int_2 (XEXP (r, 0), 0);
 356           break;
 357         default:
 358           return 0;
 359         }
 360     }
 361
 362   return t;
 363 }
 364 #endif
 365
 366 int
 367 extract_init (decl, init)
 368      tree decl ATTRIBUTE_UNUSED, init ATTRIBUTE_UNUSED;
 369 {
 370   return 0;
 371
 372 #if 0
 373   if (IS_AGGR_TYPE (TREE_TYPE (decl))
 374       || TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
 375     init = extract_aggr_init (decl, init);
 376   else
 377     init = extract_scalar_init (decl, init);
 378
 379   if (init == NULL_TREE)
 380     return 0;
 381
 382   DECL_INITIAL (decl) = init;
 383   return 1;
 384 #endif
 385 }
 386
 387 void
 388 do_case (start, end)
 389      tree start, end;
 390 {
 391   tree value1 = NULL_TREE, value2 = NULL_TREE, label;
 392
 393   if (start != NULL_TREE && TREE_TYPE (start) != NULL_TREE
 394       && POINTER_TYPE_P (TREE_TYPE (start)))
 395     error ("pointers are not permitted as case values");
 396
 397   if (end && pedantic)
 398     pedwarn ("ANSI C++ forbids range expressions in switch statement");
 399
 400   if (start)
 401     value1 = check_cp_case_value (start);
 402   if (end)
 403     value2 = check_cp_case_value (end);
 404
 405   label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
 406
 407   if (value1 != error_mark_node
 408       && value2 != error_mark_node)
 409     {
 410       tree duplicate;
 411       int success;
 412
 413       if (end)
 414         success = pushcase_range (value1, value2, convert_and_check,
 415                                   label, &duplicate);
 416       else if (start)
 417         success = pushcase (value1, convert_and_check, label, &duplicate);
 418       else
 419         success = pushcase (NULL_TREE, 0, label, &duplicate);
 420
 421       if (success == 1)
 422         {
 423           if (end)
 424             error ("case label not within a switch statement");
 425           else if (start)
 426             cp_error ("case label `%E' not within a switch statement", start);
 427           else
 428             error ("default label not within a switch statement");
 429         }
 430       else if (success == 2)
 431         {
 432           if (end)
 433             {
 434               error ("duplicate (or overlapping) case value");
 435               cp_error_at ("this is the first entry overlapping that value",
 436                            duplicate);
 437             }
 438           else if (start)
 439             {
 440               cp_error ("duplicate case value `%E'", start);
 441               cp_error_at ("previously used here", duplicate);
 442             }
 443           else
 444             {
 445               error ("multiple default labels in one switch");
 446               cp_error_at ("this is the first default label", duplicate);
 447             }
 448         }
 449       else if (success == 3)
 450         warning ("case value out of range");
 451       else if (success == 4)
 452         warning ("empty range specified");
 453       else if (success == 5)
 454         {
 455           if (end)
 456             error ("case label within scope of cleanup or variable array");
 457           else if (! start)
 458             error ("`default' label within scope of cleanup or variable array");
 459           else
 460             cp_error ("case label `%E' within scope of cleanup or variable array", start);
 461         }
 462     }
 463   define_case_label ();
 464 }