gcc/c-pragma.c

   1 /* Handle #pragma, system V.4 style.  Supports #pragma weak and #pragma pack.
   2    Copyright (C) 1992 Free Software Foundation, Inc.
   3
   4 This file is part of GNU CC.
   5
   6 GNU CC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU CC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 #include <stdio.h>
  21 #include "config.h"
  22 #include "tree.h"
  23 #include "function.h"
  24 #include "defaults.h"
  25
  26 #ifdef HANDLE_SYSV_PRAGMA
  27
  28 /* Support #pragma weak by default if WEAK_ASM_OP and ASM_OUTPUT_DEF
  29    are defined.  */
  30 #if !defined (HANDLE_PRAGMA_WEAK) && defined (WEAK_ASM_OP) && defined (ASM_OUTPUT_DEF)
  31 #define HANDLE_PRAGMA_WEAK 1
  32 #endif
  33
  34 /* See varasm.c for an identical definition.  */
  35 enum pragma_state
  36 {
  37   ps_start,
  38   ps_done,
  39   ps_bad,
  40   ps_weak,
  41   ps_name,
  42   ps_equals,
  43   ps_value,
  44   ps_pack,
  45   ps_left,
  46   ps_align,
  47   ps_right
  48 };
  49
  50 /* When structure field packing is in effect, this variable is the
  51    number of bits to use as the maximum alignment.  When packing is not
  52    in effect, this is zero. */
  53
  54 extern int maximum_field_alignment;
  55
  56 /* File used for outputting assembler code.  */
  57 extern FILE *asm_out_file;
  58
  59 /* Handle one token of a pragma directive.  TOKEN is the
  60    current token, and STRING is its printable form.  */
  61
  62 void
  63 handle_pragma_token (string, token)
  64      char *string;
  65      tree token;
  66 {
  67   static enum pragma_state state = ps_start, type;
  68   static char *name;
  69   static char *value;
  70   static int align;
  71
  72   if (string == 0)
  73     {
  74       if (type == ps_pack)
  75         {
  76           if (state == ps_right)
  77             maximum_field_alignment = align * 8;
  78           else
  79             warning ("malformed `#pragma pack'");
  80         }
  81       else if (type == ps_weak)
  82         {
  83 #ifdef HANDLE_PRAGMA_WEAK
  84           if (HANDLE_PRAGMA_WEAK)
  85             handle_pragma_weak (state, asm_out_file, name, value);
  86
  87 #endif /* HANDLE_PRAMA_WEAK */
  88         }
  89
  90       type = state = ps_start;
  91       return;
  92     }
  93
  94   switch (state)
  95     {
  96     case ps_start:
  97       if (token && TREE_CODE (token) == IDENTIFIER_NODE)
  98         {
  99           if (strcmp (IDENTIFIER_POINTER (token), "pack") == 0)
 100             type = state = ps_pack;
 101           else if (strcmp (IDENTIFIER_POINTER (token), "weak") == 0)
 102             type = state = ps_weak;
 103           else
 104             type = state = ps_done;
 105         }
 106       else
 107         type = state = ps_done;
 108       break;
 109
 110     case ps_weak:
 111       if (token && TREE_CODE (token) == IDENTIFIER_NODE)
 112         {
 113           name = IDENTIFIER_POINTER (token);
 114           state = ps_name;
 115         }
 116       else
 117         state = ps_bad;
 118       break;
 119
 120     case ps_name:
 121       state = (strcmp (string, "=") ? ps_bad : ps_equals);
 122       break;
 123
 124     case ps_equals:
 125       if (token && TREE_CODE (token) == IDENTIFIER_NODE)
 126         {
 127           value = IDENTIFIER_POINTER (token);
 128           state = ps_value;
 129         }
 130       else
 131         state = ps_bad;
 132       break;
 133
 134     case ps_value:
 135       state = ps_bad;
 136       break;
 137
 138     case ps_pack:
 139       if (strcmp (string, "(") == 0)
 140         state = ps_left;
 141       else
 142         state = ps_bad;
 143       break;
 144
 145     case ps_left:
 146       if (token && TREE_CODE (token) == INTEGER_CST
 147           && TREE_INT_CST_HIGH (token) == 0)
 148         switch (TREE_INT_CST_LOW (token))
 149           {
 150           case 1:
 151           case 2:
 152           case 4:
 153             align = TREE_INT_CST_LOW (token);
 154             state = ps_align;
 155             break;
 156
 157           default:
 158             state = ps_bad;
 159           }
 160       else if (! token && strcmp (string, ")") == 0)
 161         {
 162           align = 0;
 163           state = ps_right;
 164         }
 165       else
 166         state = ps_bad;
 167       break;
 168
 169     case ps_align:
 170       if (strcmp (string, ")") == 0)
 171         state = ps_right;
 172       else
 173         state = ps_bad;
 174       break;
 175
 176     case ps_right:
 177       state = ps_bad;
 178       break;
 179
 180     case ps_bad:
 181     case ps_done:
 182       break;
 183
 184     default:
 185       abort ();
 186     }
 187 }
 188 #endif /* HANDLE_SYSV_PRAGMA */