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