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