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 static rtx cplus_expand_expr PARAMS ((tree, rtx, enum machine_mode,
  36                                     enum expand_modifier));
  37
  38 /* Hook used by output_constant to expand language-specific
  39    constants.  */
  40
  41 tree
  42 cplus_expand_constant (cst)
  43      tree cst;
  44 {
  45   switch (TREE_CODE (cst))
  46     {
  47     case PTRMEM_CST:
  48       {
  49         tree type = TREE_TYPE (cst);
  50         tree member;
  51
  52         /* Find the member.  */
  53         member = PTRMEM_CST_MEMBER (cst);
  54
  55         if (TREE_CODE (member) == FIELD_DECL)
  56           {
  57             /* Find the offset for the field.  */
  58             tree offset = byte_position (member);
  59
  60             if (flag_new_abi)
  61               /* Under the new ABI, we use -1 to represent the NULL
  62                  pointer; non-NULL values simply contain the offset of
  63                  the data member.  */
  64               ;
  65             else
  66               /* We offset all pointer to data members by 1 so that we
  67                  can distinguish between a null pointer to data member
  68                  and the first data member of a structure.  */
  69               offset = size_binop (PLUS_EXPR, offset, size_one_node);
  70
  71             cst = fold (build1 (NOP_EXPR, type, offset));
  72           }
  73         else
  74           {
  75             tree delta, idx, pfn, delta2;
  76
  77             expand_ptrmemfunc_cst (cst, &delta, &idx, &pfn, &delta2);
  78             cst = build_ptrmemfunc1 (type, delta, idx, pfn, delta2);
  79           }
  80       }
  81       break;
  82
  83     default:
  84       /* There's nothing to do.  */
  85       break;
  86     }
  87
  88   return cst;
  89 }
  90
  91 /* Hook used by expand_expr to expand language-specific tree codes.  */
  92
  93 static rtx
  94 cplus_expand_expr (exp, target, tmode, modifier)
  95      tree exp;
  96      rtx target;
  97      enum machine_mode tmode;
  98      enum expand_modifier modifier;
  99 {
 100   tree type = TREE_TYPE (exp);
 101   register enum machine_mode mode = TYPE_MODE (type);
 102   register enum tree_code code = TREE_CODE (exp);
 103   int ignore = target == const0_rtx;
 104
 105   if (ignore)
 106     target = 0;
 107
 108   /* No sense saving up arithmetic to be done
 109      if it's all in the wrong mode to form part of an address.
 110      And force_operand won't know whether to sign-extend or zero-extend.  */
 111
 112   if (mode != Pmode && modifier == EXPAND_SUM)
 113     modifier = EXPAND_NORMAL;
 114
 115   switch (code)
 116     {
 117     case PTRMEM_CST:
 118       return expand_expr (cplus_expand_constant (exp),
 119                           target, tmode, modifier);
 120
 121     case OFFSET_REF:
 122       {
 123         return expand_expr (default_conversion (resolve_offset_ref (exp)),
 124                             target, tmode, EXPAND_NORMAL);
 125       }
 126
 127     case THROW_EXPR:
 128       expand_expr (TREE_OPERAND (exp, 0), const0_rtx, VOIDmode, 0);
 129       expand_internal_throw ();
 130       return NULL;
 131
 132     case EMPTY_CLASS_EXPR:
 133       /* We don't need to generate any code for an empty class.  */
 134       return const0_rtx;
 135
 136     case STMT_EXPR:
 137       {
 138         tree rtl_expr;
 139         rtx result;
 140
 141         /* Since expand_expr_stmt calls free_temp_slots after every
 142            expression statement, we must call push_temp_slots here.
 143            Otherwise, any temporaries in use now would be considered
 144            out-of-scope after the first EXPR_STMT from within the
 145            STMT_EXPR.  */
 146         push_temp_slots ();
 147         rtl_expr = expand_start_stmt_expr ();
 148         expand_stmt (STMT_EXPR_STMT (exp));
 149         expand_end_stmt_expr (rtl_expr);
 150         result = expand_expr (rtl_expr, target, tmode, modifier);
 151         pop_temp_slots ();
 152         return result;
 153       }
 154       break;
 155
 156     default:
 157       break;
 158     }
 159   my_friendly_abort (40);
 160   /* NOTREACHED */
 161   return NULL;
 162 }
 163
 164 void
 165 init_cplus_expand ()
 166 {
 167   lang_expand_expr = cplus_expand_expr;
 168   lang_expand_constant = cplus_expand_constant;
 169 }
 170
 171 /* If DECL had its rtl moved from where callers expect it
 172    to be, fix it up.  RESULT is the nominal rtl for the RESULT_DECL,
 173    which may be a pseudo instead of a hard register.  */
 174
 175 void
 176 fixup_result_decl (decl, result)
 177      tree decl;
 178      rtx result;
 179 {
 180   if (REG_P (result))
 181     {
 182       if (REGNO (result) >= FIRST_PSEUDO_REGISTER)
 183         {
 184           rtx real_decl_result;
 185
 186 #ifdef FUNCTION_OUTGOING_VALUE
 187           real_decl_result
 188             = FUNCTION_OUTGOING_VALUE (TREE_TYPE (decl), current_function_decl);
 189 #else
 190           real_decl_result
 191             = FUNCTION_VALUE (TREE_TYPE (decl), current_function_decl);
 192 #endif
 193           REG_FUNCTION_VALUE_P (real_decl_result) = 1;
 194           result = real_decl_result;
 195         }
 196       store_expr (decl, result, 0);
 197       emit_insn (gen_rtx (USE, VOIDmode, result));
 198     }
 199 }
 200
 201 int
 202 extract_init (decl, init)
 203      tree decl ATTRIBUTE_UNUSED, init ATTRIBUTE_UNUSED;
 204 {
 205   return 0;
 206 }
 207
 208 void
 209 do_case (start, end)
 210      tree start, end;
 211 {
 212   tree value1 = NULL_TREE, value2 = NULL_TREE, label;
 213
 214   if (start != NULL_TREE && TREE_TYPE (start) != NULL_TREE
 215       && POINTER_TYPE_P (TREE_TYPE (start)))
 216     error ("pointers are not permitted as case values");
 217
 218   if (end && pedantic)
 219     pedwarn ("ISO C++ forbids range expressions in switch statement");
 220
 221   if (start)
 222     value1 = check_cp_case_value (start);
 223   if (end)
 224     value2 = check_cp_case_value (end);
 225
 226   label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
 227
 228   if (value1 != error_mark_node
 229       && value2 != error_mark_node)
 230     {
 231       tree duplicate;
 232       int success;
 233
 234       if (end)
 235         success = pushcase_range (value1, value2, convert_and_check,
 236                                   label, &duplicate);
 237       else if (start)
 238         success = pushcase (value1, convert_and_check, label, &duplicate);
 239       else
 240         success = pushcase (NULL_TREE, 0, label, &duplicate);
 241
 242       if (success == 1)
 243         {
 244           if (end)
 245             error ("case label not within a switch statement");
 246           else if (start)
 247             cp_error ("case label `%E' not within a switch statement", start);
 248           else
 249             error ("default label not within a switch statement");
 250         }
 251       else if (success == 2)
 252         {
 253           if (end)
 254             {
 255               error ("duplicate (or overlapping) case value");
 256               cp_error_at ("this is the first entry overlapping that value",
 257                            duplicate);
 258             }
 259           else if (start)
 260             {
 261               cp_error ("duplicate case value `%E'", start);
 262               cp_error_at ("previously used here", duplicate);
 263             }
 264           else
 265             {
 266               error ("multiple default labels in one switch");
 267               cp_error_at ("this is the first default label", duplicate);
 268             }
 269         }
 270       else if (success == 3)
 271         warning ("case value out of range");
 272       else if (success == 4)
 273         warning ("empty range specified");
 274       else if (success == 5)
 275         {
 276           if (end)
 277             error ("case label within scope of cleanup or variable array");
 278           else if (! start)
 279             error ("`default' label within scope of cleanup or variable array");
 280           else
 281             cp_error ("case label `%E' within scope of cleanup or variable array", start);
 282         }
 283     }
 284
 285   current_function_return_value = NULL_TREE;
 286 }