freebsd-dev/contrib/gcc/c-pragma.c
1999-10-16 06:09:09 +00:00

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/* Handle #pragma, system V.4 style. Supports #pragma weak and #pragma pack.
Copyright (C) 1992, 1997, 1998, 1999 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 "except.h"
#include "function.h"
#include "defaults.h"
#include "c-pragma.h"
#include "flags.h"
#include "toplev.h"
#ifdef HANDLE_GENERIC_PRAGMAS
#ifdef HANDLE_PRAGMA_PACK
/* When structure field packing is in effect, this variable is the
number of bits to use as the maximum alignment. When packing is not
in effect, this is zero. */
extern int maximum_field_alignment;
#endif
#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;
static int push_alignment PROTO((int, tree));
static int pop_alignment PROTO((tree));
/* 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));
if (entry == NULL)
{
warning ("Out of memory pushing #pragma pack");
return 0;
}
entry->alignment = alignment;
entry->num_pushes = 1;
entry->id = id;
entry->prev = alignment_stack;
alignment_stack = entry;
maximum_field_alignment = alignment * 8;
}
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 = 0;
else
maximum_field_alignment = entry->alignment * 8;
free (alignment_stack);
alignment_stack = entry;
}
return 1;
}
/* Generate 'packed' and 'aligned' attributes for decls whilst a
#pragma pack(push... is in effect. */
void
insert_pack_attributes (node, attributes, prefix)
tree node;
tree * attributes;
tree * prefix;
{
tree a;
int field_alignment;
/* If we are not packing, then there is nothing to do. */
if (maximum_field_alignment == 0
|| alignment_stack == NULL)
return;
/* We are only interested in fields. */
if (TREE_CODE_CLASS (TREE_CODE (node)) != 'd'
|| TREE_CODE (node) != FIELD_DECL)
return;
field_alignment = TYPE_ALIGN (TREE_TYPE (node));
if (field_alignment <= 0 || field_alignment > maximum_field_alignment)
field_alignment = maximum_field_alignment;
/* Add a 'packed' attribute. */
* attributes = tree_cons (get_identifier ("packed"), NULL, * attributes);
/* If the alignment is > 8 then add an alignment attribute as well. */
if (field_alignment > 8)
{
/* If the aligned attribute is already present then do not override it. */
for (a = * attributes; a; a = TREE_CHAIN (a))
{
tree name = TREE_PURPOSE (a);
if (strcmp (IDENTIFIER_POINTER (name), "aligned") == 0)
break;
}
if (a == NULL)
for (a = * prefix; a; a = TREE_CHAIN (a))
{
tree name = TREE_PURPOSE (a);
if (strcmp (IDENTIFIER_POINTER (name), "aligned") == 0)
break;
}
if (a == NULL)
{
* attributes = tree_cons
(get_identifier ("aligned"),
tree_cons (NULL,
build_int_2 (field_alignment / 8, 0),
NULL),
* attributes);
}
}
return;
}
#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;
static char * name;
static char * value;
static int align;
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 * 8;
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 */
}
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
break;
#ifdef HANDLE_PRAGMA_WEAK
case ps_weak:
name = permalloc (strlen (string) + 1);
if (name == NULL)
{
warning ("Out of memory parsing #pragma weak");
state = ps_bad;
}
else
{
strcpy (name, string);
state = ps_name;
}
break;
case ps_name:
state = (strcmp (string, "=") ? ps_bad : ps_equals);
break;
case ps_equals:
value = permalloc (strlen (string) + 1);
if (value == NULL)
{
warning ("Out of memory parsing #pragma weak");
state = ps_bad;
}
else
{
strcpy (value, 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:
align = TREE_INT_CST_LOW (token);
switch (align)
{
case 1:
case 2:
case 4:
case 8:
case 16:
state = ps_align;
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_bad:
case ps_done:
break;
default:
abort ();
}
return 1;
}
#endif /* HANDLE_GENERIC_PRAGMAS */