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