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