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 (TREE_CODE (func) == ADDR_EXPR
 158             && TREE_CODE (TREE_OPERAND (func, 0)) == FUNCTION_DECL
 159             && DECL_CONSTRUCTOR_P (TREE_OPERAND (func, 0)))
 160           {
 161             type = build_pointer_type (type);
 162             /* Don't clobber a value that might be part of a default
 163                parameter value.  */
 164             mark_addressable (slot);
 165             if (TREE_PERMANENT (args))
 166               args = expr_tree_cons (0, build1 (ADDR_EXPR, type, slot),
 167                                 TREE_CHAIN (args));
 168             else
 169               TREE_VALUE (args) = build1 (ADDR_EXPR, type, slot);
 170             call_target = 0;
 171           }
 172         else
 173           {
 174             call_target = target;
 175 #ifdef PCC_STATIC_STRUCT_RETURN
 176             if (aggregate_value_p (type))
 177               {
 178                 pcc_struct_return = 1;
 179                 call_target = 0;
 180               }
 181 #endif
 182           }
 183
 184         call_exp = build (CALL_EXPR, type, func, args, NULL_TREE);
 185         TREE_SIDE_EFFECTS (call_exp) = 1;
 186         return_target = expand_call (call_exp, call_target, ignore);
 187
 188         if (call_target)
 189           /* Trust that the right thing has been done; it's too hard to
 190              verify.  */
 191           return return_target;
 192
 193         /* If we're suffering under the ancient PCC_STATIC_STRUCT_RETURN
 194            calling convention, we need to copy the return value out of
 195            the static return buffer into slot.  */
 196         if (pcc_struct_return)
 197           {
 198             extern int flag_access_control;
 199             int old_ac = flag_access_control;
 200
 201             tree init = build_decl (VAR_DECL, NULL_TREE,
 202                                     build_reference_type (type));
 203             DECL_RTL (init) = XEXP (return_target, 0);
 204             init = convert_from_reference (init);
 205
 206             flag_access_control = 0;
 207             expand_expr (build_aggr_init (slot, init,
 208                                           LOOKUP_ONLYCONVERTING),
 209                          target, tmode, EXPAND_NORMAL);
 210             flag_access_control = old_ac;
 211
 212             if (TYPE_NEEDS_DESTRUCTOR (type))
 213               {
 214                 init = maybe_build_cleanup (init);
 215                 if (init != NULL_TREE)
 216                   expand_expr (init, const0_rtx, VOIDmode, 0);
 217               }
 218           }
 219
 220         return DECL_RTL (slot);
 221       }
 222
 223     case PTRMEM_CST:
 224       return expand_expr (cplus_expand_constant (exp),
 225                           target, tmode, modifier);
 226
 227     case OFFSET_REF:
 228       {
 229         return expand_expr (default_conversion (resolve_offset_ref (exp)),
 230                             target, tmode, EXPAND_NORMAL);
 231       }
 232
 233     case THUNK_DECL:
 234       return DECL_RTL (exp);
 235
 236     case THROW_EXPR:
 237       expand_throw (TREE_OPERAND (exp, 0));
 238       return NULL;
 239
 240     case VEC_INIT_EXPR:
 241       return expand_expr
 242         (build_vec_init
 243          (NULL_TREE, TREE_OPERAND (exp, 0),
 244           build_binary_op (MINUS_EXPR, TREE_OPERAND (exp, 2),
 245                            integer_one_node),
 246           TREE_OPERAND (exp, 1), 0), target, tmode, modifier);
 247
 248     case NEW_EXPR:
 249       return expand_expr (build_new_1 (exp), target, tmode, modifier);
 250
 251     case STMT_EXPR:
 252       {
 253         tree rtl_expr = begin_stmt_expr ();
 254         tree block = expand_stmt (STMT_EXPR_STMT (exp));
 255         finish_stmt_expr (rtl_expr, block);
 256         return expand_expr (rtl_expr, target, tmode, modifier);
 257       }
 258       break;
 259
 260     default:
 261       break;
 262     }
 263   my_friendly_abort (40);
 264   /* NOTREACHED */
 265   return NULL;
 266 }
 267
 268 void
 269 init_cplus_expand ()
 270 {
 271   lang_expand_expr = cplus_expand_expr;
 272   lang_expand_constant = cplus_expand_constant;
 273 }
 274
 275 /* If DECL had its rtl moved from where callers expect it
 276    to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
 277    which may be a pseudo instead of a hard register.  */
 278
 279 void
 280 fixup_result_decl (decl, result)
 281      tree decl;
 282      rtx result;
 283 {
 284   if (REG_P (result))
 285     {
 286       if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
 287         {
 288           rtx real_decl_result;
 289
 290 #ifdef FUNCTION_OUTGOING_VALUE
 291           real_decl_result
 292             = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
 293 #else
 294           real_decl_result
 295             = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
 296 #endif
 297           REG_FUNCTION_VALUE_P (real_decl_result) = 1;
 298           result = real_decl_result;
 299         }
 300       store_expr (decl, result, 0);
 301       emit_insn (gen_rtx (USE, VOIDmode, result));
 302     }
 303 }
 304
 305 #if 0
 306 /* Expand this initialization inline and see if it's simple enough that
 307    it can be done at compile-time.  */
 308
 309 static tree
 310 extract_aggr_init (decl, init)
 311      tree decl, init;
 312 {
 313   return 0;
 314 }
 315
 316 static tree
 317 extract_scalar_init (decl, init)
 318      tree decl, init;
 319 {
 320   rtx value, insns, insn;
 321   extern struct obstack temporary_obstack;
 322   tree t = NULL_TREE;
 323
 324   push_obstacks (&temporary_obstack, &temporary_obstack);
 325   start_sequence ();
 326   value = expand_expr (init, NULL_RTX, VOIDmode, 0);
 327   insns = get_insns ();
 328   end_sequence ();
 329   reg_scan (insns, max_reg_num (), 0);
 330   jump_optimize (insns, 0, 0, 1);
 331   pop_obstacks ();
 332
 333   for (insn = insns; insn; insn = NEXT_INSN (insn))
 334     {
 335       rtx r, to;
 336
 337       if (GET_CODE (insn) == NOTE)
 338         continue;
 339       else if (GET_CODE (insn) != INSN)
 340         return 0;
 341
 342       r = PATTERN (insn);
 343       if (GET_CODE (r) != SET)
 344         return 0;
 345
 346       to = XEXP (r, 0);
 347
 348       if (! (to == value
 349              || (GET_CODE (to) == SUBREG && XEXP (to, 0) == value)))
 350         return 0;
 351
 352       r = XEXP (r, 1);
 353
 354       switch (GET_CODE (r))
 355         {
 356         case CONST_INT:
 357           t = build_int_2 (XEXP (r, 0), 0);
 358           break;
 359         default:
 360           return 0;
 361         }
 362     }
 363
 364   return t;
 365 }
 366 #endif
 367
 368 int
 369 extract_init (decl, init)
 370      tree decl ATTRIBUTE_UNUSED, init ATTRIBUTE_UNUSED;
 371 {
 372   return 0;
 373
 374 #if 0
 375   if (IS_AGGR_TYPE (TREE_TYPE (decl))
 376       || TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
 377     init = extract_aggr_init (decl, init);
 378   else
 379     init = extract_scalar_init (decl, init);
 380
 381   if (init == NULL_TREE)
 382     return 0;
 383
 384   DECL_INITIAL (decl) = init;
 385   return 1;
 386 #endif
 387 }
 388
 389 void
 390 do_case (start, end)
 391      tree start, end;
 392 {
 393   tree value1 = NULL_TREE, value2 = NULL_TREE, label;
 394
 395   if (start != NULL_TREE && TREE_TYPE (start) != NULL_TREE
 396       && POINTER_TYPE_P (TREE_TYPE (start)))
 397     error ("pointers are not permitted as case values");
 398
 399   if (end && pedantic)
 400     pedwarn ("ANSI C++ forbids range expressions in switch statement");
 401
 402   if (start)
 403     value1 = check_cp_case_value (start);
 404   if (end)
 405     value2 = check_cp_case_value (end);
 406
 407   label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
 408
 409   if (value1 != error_mark_node
 410       && value2 != error_mark_node)
 411     {
 412       tree duplicate;
 413       int success;
 414
 415       if (end)
 416         success = pushcase_range (value1, value2, convert_and_check,
 417                                   label, &duplicate);
 418       else if (start)
 419         success = pushcase (value1, convert_and_check, label, &duplicate);
 420       else
 421         success = pushcase (NULL_TREE, 0, label, &duplicate);
 422
 423       if (success == 1)
 424         {
 425           if (end)
 426             error ("case label not within a switch statement");
 427           else if (start)
 428             cp_error ("case label `%E' not within a switch statement", start);
 429           else
 430             error ("default label not within a switch statement");
 431         }
 432       else if (success == 2)
 433         {
 434           if (end)
 435             {
 436               error ("duplicate (or overlapping) case value");
 437               cp_error_at ("this is the first entry overlapping that value",
 438                            duplicate);
 439             }
 440           else if (start)
 441             {
 442               cp_error ("duplicate case value `%E'", start);
 443               cp_error_at ("previously used here", duplicate);
 444             }
 445           else
 446             {
 447               error ("multiple default labels in one switch");
 448               cp_error_at ("this is the first default label", duplicate);
 449             }
 450         }
 451       else if (success == 3)
 452         warning ("case value out of range");
 453       else if (success == 4)
 454         warning ("empty range specified");
 455       else if (success == 5)
 456         {
 457           if (end)
 458             error ("case label within scope of cleanup or variable array");
 459           else if (! start)
 460             error ("`default' label within scope of cleanup or variable array");
 461           else
 462             cp_error ("case label `%E' within scope of cleanup or variable array", start);
 463         }
 464     }
 465   define_case_label ();
 466 }