465 lines
10 KiB
C
465 lines
10 KiB
C
/* Handle #pragma, system V.4 style. Supports #pragma weak and #pragma pack.
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Copyright (C) 1992, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "config.h"
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#include "system.h"
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#include "rtl.h"
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#include "tree.h"
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#include "function.h"
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#include "defaults.h"
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#include "c-pragma.h"
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#include "flags.h"
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#include "toplev.h"
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#include "ggc.h"
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#ifdef HANDLE_GENERIC_PRAGMAS
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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typedef struct align_stack
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{
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int alignment;
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unsigned int num_pushes;
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tree id;
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struct align_stack * prev;
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} align_stack;
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static struct align_stack * alignment_stack = NULL;
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/* If we have a "global" #pragma pack(<n>) if effect when the first
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#pragma push(pack,<n>) is encountered, this stores the the value of
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maximum_field_alignment in effect. When the final pop_alignment()
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happens, we restore the value to this, not to a value of 0 for
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maximum_field_alignment. Value is in bits. */
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static int default_alignment;
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static int push_alignment PARAMS ((int, tree));
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static int pop_alignment PARAMS ((tree));
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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static void mark_align_stack PARAMS ((void *));
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#endif
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/* Push an alignment value onto the stack. */
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static int
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push_alignment (alignment, id)
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int alignment;
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tree id;
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{
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switch (alignment)
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{
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case 0:
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case 1:
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case 2:
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case 4:
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case 8:
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case 16:
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break;
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default:
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warning ("\
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Alignment must be a small power of two, not %d, in #pragma pack",
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alignment);
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return 0;
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}
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if (alignment_stack == NULL
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|| alignment_stack->alignment != alignment
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|| id != NULL_TREE)
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{
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align_stack * entry;
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entry = (align_stack *) xmalloc (sizeof (* entry));
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entry->alignment = alignment;
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entry->num_pushes = 1;
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entry->id = id;
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entry->prev = alignment_stack;
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/* The current value of maximum_field_alignment is not necessarily
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0 since there may be a #pragma pack(<n>) in effect; remember it
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so that we can restore it after the final #pragma pop(). */
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if (alignment_stack == NULL)
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default_alignment = maximum_field_alignment;
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alignment_stack = entry;
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maximum_field_alignment = alignment * BITS_PER_UNIT;
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}
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else
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alignment_stack->num_pushes ++;
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return 1;
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}
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/* Undo a push of an alignment onto the stack. */
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static int
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pop_alignment (id)
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tree id;
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{
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align_stack * entry;
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if (alignment_stack == NULL)
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{
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warning ("\
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#pragma pack (pop) encountered without matching #pragma pack (push, <n>)"
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);
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return 0;
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}
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/* If we got an identifier, strip away everything above the target
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entry so that the next step will restore the state just below it. */
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if (id)
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{
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for (entry = alignment_stack; entry; entry = entry->prev)
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if (entry->id == id)
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{
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entry->num_pushes = 1;
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alignment_stack = entry;
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break;
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}
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if (entry == NULL)
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warning ("\
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#pragma pack(pop, %s) encountered without matching #pragma pack(push, %s, <n>)"
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, IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id));
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}
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if (-- alignment_stack->num_pushes == 0)
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{
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entry = alignment_stack->prev;
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if (entry == NULL)
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maximum_field_alignment = default_alignment;
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else
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maximum_field_alignment = entry->alignment * BITS_PER_UNIT;
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free (alignment_stack);
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alignment_stack = entry;
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}
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return 1;
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}
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#endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
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/* Handle one token of a pragma directive. TOKEN is the current token, and
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STRING is its printable form. Some front ends do not support generating
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tokens, and will only pass in a STRING. Also some front ends will reuse
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the buffer containing STRING, so it must be copied to a local buffer if
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it needs to be preserved.
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If STRING is non-NULL, then the return value will be ignored, and there
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will be futher calls to handle_pragma_token in order to handle the rest of
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the line containing the #pragma directive. If STRING is NULL, the entire
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line has now been presented to handle_pragma_token and the return value
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should be zero if the pragma flawed in some way, or if the pragma was not
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recognised, and non-zero if it was successfully handled. */
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int
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handle_pragma_token (string, token)
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const char *string;
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tree token;
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{
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static enum pragma_state state = ps_start;
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static enum pragma_state type;
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#ifdef HANDLE_PRAGMA_WEAK
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static char *name;
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static char *value;
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#endif
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#if defined(HANDLE_PRAGMA_PACK) || defined(HANDLE_PRAGMA_PACK_PUSH_POP)
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static unsigned int align;
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#endif
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static tree id;
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/* If we have reached the end of the #pragma directive then
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determine what value we should return. */
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if (string == NULL)
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{
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int ret_val = 0;
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switch (type)
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{
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default:
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abort ();
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break;
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case ps_done:
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/* The pragma was not recognised. */
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break;
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#ifdef HANDLE_PRAGMA_PACK
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case ps_pack:
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if (state == ps_right)
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{
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maximum_field_alignment = align * BITS_PER_UNIT;
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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default_alignment = maximum_field_alignment;
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#endif
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ret_val = 1;
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}
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else
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warning ("malformed `#pragma pack'");
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break;
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#endif /* HANDLE_PRAGMA_PACK */
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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case ps_push:
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if (state == ps_right)
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ret_val = push_alignment (align, id);
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else
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warning ("malformed '#pragma pack(push[,id],<n>)'");
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break;
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case ps_pop:
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if (state == ps_right)
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ret_val = pop_alignment (id);
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else
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warning ("malformed '#pragma pack(pop[,id])'");
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break;
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#endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
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#ifdef HANDLE_PRAGMA_WEAK
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case ps_weak:
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if (HANDLE_PRAGMA_WEAK)
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{
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if (state == ps_name)
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ret_val = add_weak (name, NULL);
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else if (state == ps_value)
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ret_val = add_weak (name, value);
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else
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warning ("malformed `#pragma weak'");
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}
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else
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ret_val = 1; /* Ignore the pragma. */
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break;
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#endif /* HANDLE_PRAGMA_WEAK */
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case ps_poison:
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ret_val = 1;
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break;
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}
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type = state = ps_start;
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id = NULL_TREE;
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return ret_val;
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}
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/* If we have been given a token, but it is not an identifier,
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or a small constant, then something has gone wrong. */
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if (token)
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{
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switch (TREE_CODE (token))
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{
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case IDENTIFIER_NODE:
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break;
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case INTEGER_CST:
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if (TREE_INT_CST_HIGH (token) != 0)
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return 0;
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break;
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default:
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return 0;
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}
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}
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switch (state)
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{
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case ps_start:
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type = state = ps_done;
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#ifdef HANDLE_PRAGMA_PACK
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if (strcmp (string, "pack") == 0)
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type = state = ps_pack;
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#endif
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#ifdef HANDLE_PRAGMA_WEAK
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if (strcmp (string, "weak") == 0)
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type = state = ps_weak;
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#endif
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if (strcmp (string, "poison") == 0)
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type = state = ps_poison;
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break;
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#ifdef HANDLE_PRAGMA_WEAK
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case ps_weak:
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name = xstrdup (string);
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state = ps_name;
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break;
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case ps_name:
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state = (strcmp (string, "=") ? ps_bad : ps_equals);
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break;
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case ps_equals:
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value = xstrdup (string);
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state = ps_value;
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break;
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case ps_value:
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state = ps_bad;
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break;
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#endif /* HANDLE_PRAGMA_WEAK */
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#ifdef HANDLE_PRAGMA_PACK
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case ps_pack:
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state = (strcmp (string, "(") ? ps_bad : ps_left);
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break;
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case ps_left:
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if (token == NULL_TREE)
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{
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/* #pragma pack () resets packing rules to their
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defaults. */
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if (strcmp (string, ")") == 0)
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{
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align = 0;
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state = ps_right;
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}
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else
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state = ps_bad;
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}
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else if (TREE_CODE (token) == INTEGER_CST)
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goto handle_align;
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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else if (TREE_CODE (token) == IDENTIFIER_NODE)
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{
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if (strcmp (string, "push") == 0)
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type = state = ps_push;
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else if (strcmp (string, "pop") == 0)
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type = state = ps_pop;
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else
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state = ps_bad;
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}
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#endif
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else
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state = ps_bad;
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break;
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handle_align:
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switch (tree_log2 (token))
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{
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case 0:
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case 1:
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case 2:
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case 3:
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case 4:
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state = ps_align;
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align = 1 << tree_log2 (token);
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break;
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default:
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state = ps_bad;
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break;
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}
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break;
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case ps_align:
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state = (strcmp (string, ")") ? ps_bad : ps_right);
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break;
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case ps_right:
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state = ps_bad;
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break;
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#endif /* HANDLE_PRAGMA_PACK */
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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case ps_push:
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state = (strcmp (string, ",") ? ps_bad : ps_pushcomma);
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break;
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case ps_pushid:
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state = (strcmp (string, ",") ? ps_bad : ps_pushcomma2);
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break;
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case ps_pushcomma:
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if (token && TREE_CODE (token) == IDENTIFIER_NODE)
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{
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id = token;
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state = ps_pushid;
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break;
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}
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/* else fall through */
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case ps_pushcomma2:
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if (token && TREE_CODE (token) == INTEGER_CST)
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goto handle_align;
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else
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state = ps_bad;
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break;
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case ps_pop:
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if (strcmp (string, ",") == 0)
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state = ps_popcomma;
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else
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state = (strcmp (string, ")") ? ps_bad : ps_right);
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break;
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case ps_popcomma:
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if (token && TREE_CODE (token) == IDENTIFIER_NODE)
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{
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id = token;
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state = ps_align;
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}
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else
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state = ps_bad;
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break;
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#endif /* HANDLE_PRAGMA_PACK_PUSH_POP */
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case ps_poison:
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if (token && TREE_CODE (token) != IDENTIFIER_NODE)
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state = ps_bad;
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break;
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case ps_bad:
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case ps_done:
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break;
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default:
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abort ();
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}
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return 1;
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}
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#endif /* HANDLE_GENERIC_PRAGMAS */
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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static void
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mark_align_stack (p)
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void *p;
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{
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align_stack *a = *(align_stack **) p;
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while (a)
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{
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ggc_mark_tree (a->id);
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a = a->prev;
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}
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}
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#endif
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void
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init_pragma ()
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{
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#ifdef HANDLE_PRAGMA_PACK_PUSH_POP
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ggc_add_root (&alignment_stack, 1, sizeof(alignment_stack),
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mark_align_stack);
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#endif
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}
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