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, 1996, 1997, 1998,
   4    2000 Free Software Foundation, Inc.
   5
   6 This file is part of GNU CC.
   7
   8 GNU CC is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GNU CC is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GNU CC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 59 Temple Place - Suite 330,
  21 Boston, MA 02111-1307, USA.  */
  22
  23
  24 #include "config.h"
  25 #include "system.h"
  26 #include "rtl.h"
  27 #include "tree.h"
  28 #include "flags.h"
  29 #include "expr.h"
  30 #include "cp-tree.h"
  31 #include "toplev.h"
  32 #include "except.h"
  33 #include "tm_p.h"
  34
  35 #if 0
  36 static tree extract_aggr_init PARAMS ((tree, tree));
  37 static tree extract_scalar_init PARAMS ((tree, tree));
  38 #endif
  39 static rtx cplus_expand_expr PARAMS ((tree, rtx, enum machine_mode,
  40                                     enum expand_modifier));
  41
  42 /* Hook used by output_constant to expand language-specific
  43    constants.  */
  44
  45 tree
  46 cplus_expand_constant (cst)
  47      tree cst;
  48 {
  49   switch (TREE_CODE (cst))
  50     {
  51     case PTRMEM_CST:
  52       {
  53         tree type = TREE_TYPE (cst);
  54         tree member;
  55         tree offset;
  56
  57         /* Find the member.  */
  58         member = PTRMEM_CST_MEMBER (cst);
  59
  60         if (TREE_CODE (member) == FIELD_DECL)
  61           {
  62             /* Find the offset for the field.  */
  63             offset = convert (sizetype,
  64                               size_binop (EASY_DIV_EXPR,
  65                                           bit_position (member),
  66                                           bitsize_int (BITS_PER_UNIT)));
  67
  68             /* We offset all pointer to data members by 1 so that we
  69                can distinguish between a null pointer to data member
  70                and the first data member of a structure.  */
  71             offset = size_binop (PLUS_EXPR, offset, size_one_node);
  72             cst = cp_convert (type, offset);
  73           }
  74         else
  75           {
  76             tree delta;
  77             tree idx;
  78             tree pfn;
  79             tree delta2;
  80
  81             expand_ptrmemfunc_cst (cst, &delta, &idx, &pfn, &delta2);
  82
  83             cst = build_ptrmemfunc1 (type, delta, idx,
  84                                      pfn, delta2);
  85           }
  86       }
  87       break;
  88
  89     default:
  90       /* There's nothing to do.  */
  91       break;
  92     }
  93
  94   return cst;
  95 }
  96
  97 /* Hook used by expand_expr to expand language-specific tree codes.  */
  98
  99 static rtx
 100 cplus_expand_expr (exp, target, tmode, modifier)
 101      tree exp;
 102      rtx target;
 103      enum machine_mode tmode;
 104      enum expand_modifier modifier;
 105 {
 106   tree type = TREE_TYPE (exp);
 107   register enum machine_mode mode = TYPE_MODE (type);
 108   register enum tree_code code = TREE_CODE (exp);
 109   int ignore = target == const0_rtx;
 110
 111   if (ignore)
 112     target = 0;
 113
 114   /* No sense saving up arithmetic to be done
 115      if it's all in the wrong mode to form part of an address.
 116      And force_operand won't know whether to sign-extend or zero-extend.  */
 117
 118   if (mode != Pmode && modifier == EXPAND_SUM)
 119     modifier = EXPAND_NORMAL;
 120
 121   switch (code)
 122     {
 123     case PTRMEM_CST:
 124       return expand_expr (cplus_expand_constant (exp),
 125                           target, tmode, modifier);
 126
 127     case OFFSET_REF:
 128       {
 129         return expand_expr (default_conversion (resolve_offset_ref (exp)),
 130                             target, tmode, EXPAND_NORMAL);
 131       }
 132
 133     case THUNK_DECL:
 134       my_friendly_assert (DECL_RTL (exp) != NULL_RTX, 20000115);
 135       return DECL_RTL (exp);
 136
 137     case THROW_EXPR:
 138       expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
 139       expand_internal_throw ();
 140       return NULL;
 141
 142     case EMPTY_CLASS_EXPR:
 143       /* We don't need to generate any code for an empty class.  */
 144       return const0_rtx;
 145
 146     case STMT_EXPR:
 147       {
 148         tree rtl_expr = expand_start_stmt_expr ();
 149         expand_stmt (STMT_EXPR_STMT (exp));
 150         expand_end_stmt_expr (rtl_expr);
 151         return expand_expr (rtl_expr, target, tmode, modifier);
 152       }
 153       break;
 154
 155     default:
 156       break;
 157     }
 158   my_friendly_abort (40);
 159   /* NOTREACHED */
 160   return NULL;
 161 }
 162
 163 void
 164 init_cplus_expand ()
 165 {
 166   lang_expand_expr = cplus_expand_expr;
 167   lang_expand_constant = cplus_expand_constant;
 168 }
 169
 170 /* If DECL had its rtl moved from where callers expect it
 171    to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
 172    which may be a pseudo instead of a hard register.  */
 173
 174 void
 175 fixup_result_decl (decl, result)
 176      tree decl;
 177      rtx result;
 178 {
 179   if (REG_P (result))
 180     {
 181       if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
 182         {
 183           rtx real_decl_result;
 184
 185 #ifdef FUNCTION_OUTGOING_VALUE
 186           real_decl_result
 187             = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
 188 #else
 189           real_decl_result
 190             = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
 191 #endif
 192           REG_FUNCTION_VALUE_P (real_decl_result) = 1;
 193           result = real_decl_result;
 194         }
 195       store_expr (decl, result, 0);
 196       emit_insn (gen_rtx (USE, VOIDmode, result));
 197     }
 198 }
 199
 200 #if 0
 201 /* Expand this initialization inline and see if it's simple enough that
 202    it can be done at compile-time.  */
 203
 204 static tree
 205 extract_aggr_init (decl, init)
 206      tree decl, init;
 207 {
 208   return 0;
 209 }
 210
 211 static tree
 212 extract_scalar_init (decl, init)
 213      tree decl, init;
 214 {
 215   rtx value, insns, insn;
 216   extern struct obstack temporary_obstack;
 217   tree t = NULL_TREE;
 218
 219   start_sequence ();
 220   value = expand_expr (init, NULL_RTX, VOIDmode, 0);
 221   insns = get_insns ();
 222   end_sequence ();
 223   reg_scan (insns, max_reg_num (), 0);
 224   jump_optimize (insns, 0, 0, 1);
 225
 226   for (insn = insns; insn; insn = NEXT_INSN (insn))
 227     {
 228       rtx r, to;
 229
 230       if (GET_CODE (insn) == NOTE)
 231         continue;
 232       else if (GET_CODE (insn) != INSN)
 233         return 0;
 234
 235       r = PATTERN (insn);
 236       if (GET_CODE (r) != SET)
 237         return 0;
 238
 239       to = XEXP (r, 0);
 240
 241       if (! (to == value
 242              || (GET_CODE (to) == SUBREG && XEXP (to, 0) == value)))
 243         return 0;
 244
 245       r = XEXP (r, 1);
 246
 247       switch (GET_CODE (r))
 248         {
 249         case CONST_INT:
 250           t = build_int_2 (XEXP (r, 0), 0);
 251           break;
 252         default:
 253           return 0;
 254         }
 255     }
 256
 257   return t;
 258 }
 259 #endif
 260
 261 int
 262 extract_init (decl, init)
 263      tree decl ATTRIBUTE_UNUSED, init ATTRIBUTE_UNUSED;
 264 {
 265   return 0;
 266
 267 #if 0
 268   if (IS_AGGR_TYPE (TREE_TYPE (decl))
 269       || TREE_CODE (TREE_TYPE (decl)) == ARRAY_TYPE)
 270     init = extract_aggr_init (decl, init);
 271   else
 272     init = extract_scalar_init (decl, init);
 273
 274   if (init == NULL_TREE)
 275     return 0;
 276
 277   DECL_INITIAL (decl) = init;
 278   return 1;
 279 #endif
 280 }
 281
 282 void
 283 do_case (start, end)
 284      tree start, end;
 285 {
 286   tree value1 = NULL_TREE, value2 = NULL_TREE, label;
 287
 288   if (start != NULL_TREE && TREE_TYPE (start) != NULL_TREE
 289       && POINTER_TYPE_P (TREE_TYPE (start)))
 290     error ("pointers are not permitted as case values");
 291
 292   if (end && pedantic)
 293     pedwarn ("ISO C++ forbids range expressions in switch statement");
 294
 295   if (start)
 296     value1 = check_cp_case_value (start);
 297   if (end)
 298     value2 = check_cp_case_value (end);
 299
 300   label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
 301
 302   if (value1 != error_mark_node
 303       && value2 != error_mark_node)
 304     {
 305       tree duplicate;
 306       int success;
 307
 308       if (end)
 309         success = pushcase_range (value1, value2, convert_and_check,
 310                                   label, &duplicate);
 311       else if (start)
 312         success = pushcase (value1, convert_and_check, label, &duplicate);
 313       else
 314         success = pushcase (NULL_TREE, 0, label, &duplicate);
 315
 316       if (success == 1)
 317         {
 318           if (end)
 319             error ("case label not within a switch statement");
 320           else if (start)
 321             cp_error ("case label `%E' not within a switch statement", start);
 322           else
 323             error ("default label not within a switch statement");
 324         }
 325       else if (success == 2)
 326         {
 327           if (end)
 328             {
 329               error ("duplicate (or overlapping) case value");
 330               cp_error_at ("this is the first entry overlapping that value",
 331                            duplicate);
 332             }
 333           else if (start)
 334             {
 335               cp_error ("duplicate case value `%E'", start);
 336               cp_error_at ("previously used here", duplicate);
 337             }
 338           else
 339             {
 340               error ("multiple default labels in one switch");
 341               cp_error_at ("this is the first default label", duplicate);
 342             }
 343         }
 344       else if (success == 3)
 345         warning ("case value out of range");
 346       else if (success == 4)
 347         warning ("empty range specified");
 348       else if (success == 5)
 349         {
 350           if (end)
 351             error ("case label within scope of cleanup or variable array");
 352           else if (! start)
 353             error ("`default' label within scope of cleanup or variable array");
 354           else
 355             cp_error ("case label `%E' within scope of cleanup or variable array", start);
 356         }
 357     }
 358
 359   current_function_return_value = NULL_TREE;
 360 }