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[PATCH] for bug 7054 (#pragma pack)
- From: "Jan Beulich" <JBeulich at novell dot com>
- To: <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 07 May 2004 16:54:56 +0200
- Subject: [PATCH] for bug 7054 (#pragma pack)
.. plus additionally a means to set the (initial) packing value from
the command line.
gcc-3.4.0-pragma-pack.patch:
--- 3.4.0-base/gcc/c-pragma.c 2004-01-24 00:35:53.000000000 +0100
+++ 3.4.0/gcc/c-pragma.c 2004-05-03 13:45:55.000000000 +0200
@@ -41,7 +41,6 @@
typedef struct align_stack GTY(())
{
int alignment;
- unsigned int num_pushes;
tree id;
struct align_stack * prev;
} align_stack;
@@ -58,8 +57,9 @@
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;
-#define SET_GLOBAL_ALIGNMENT(ALIGN) \
- (default_alignment = maximum_field_alignment = (ALIGN))
+#define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment =
*(alignment_stack == NULL \
+ ? &default_alignment \
+ : &alignment_stack->alignment) = (ALIGN))
static void push_alignment (int, tree);
static void pop_alignment (tree);
@@ -68,31 +68,23 @@
static void
push_alignment (int alignment, tree id)
{
- if (alignment_stack == NULL
- || alignment_stack->alignment != alignment
- || id != NULL_TREE)
- {
- align_stack * entry;
-
- entry = ggc_alloc (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;
+ align_stack * entry;
- maximum_field_alignment = alignment;
- }
- else
- alignment_stack->num_pushes ++;
+ entry = ggc_alloc (sizeof (* entry));
+
+ entry->alignment = alignment;
+ 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;
}
/* Undo a push of an alignment onto the stack. */
@@ -102,12 +94,7 @@
align_stack * entry;
if (alignment_stack == NULL)
- {
- warning ("\
-#pragma pack (pop) encountered without matching #pragma pack (push,
<n>)"
- );
- return;
- }
+ GCC_BAD("#pragma pack (pop) encountered without matching #pragma
pack (push)");
/* If we got an identifier, strip away everything above the target
entry so that the next step will restore the state just below it.
*/
@@ -116,27 +103,20 @@
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>)"
+#pragma pack(pop, %s) encountered without matching #pragma pack(push,
%s)"
, IDENTIFIER_POINTER (id), IDENTIFIER_POINTER (id));
}
- if (-- alignment_stack->num_pushes == 0)
- {
- entry = alignment_stack->prev;
+ entry = alignment_stack->prev;
- if (entry == NULL)
- maximum_field_alignment = default_alignment;
- else
- maximum_field_alignment = entry->alignment;
+ maximum_field_alignment = entry ? entry->alignment :
default_alignment;
- alignment_stack = entry;
- }
+ alignment_stack = entry;
}
#else /* not HANDLE_PRAGMA_PACK_PUSH_POP */
#define SET_GLOBAL_ALIGNMENT(ALIGN) (maximum_field_alignment =
(ALIGN))
@@ -149,7 +129,9 @@
/* #pragma pack ()
#pragma pack (N)
+ #pragma pack (push)
#pragma pack (push, N)
+ #pragma pack (push, ID)
#pragma pack (push, ID, N)
#pragma pack (pop)
#pragma pack (pop, ID) */
@@ -168,7 +150,7 @@
if (token == CPP_CLOSE_PAREN)
{
action = set;
- align = 0;
+ align = initial_max_fld_align;
}
else if (token == CPP_NUMBER)
{
@@ -179,8 +161,8 @@
}
else if (token == CPP_NAME)
{
-#define GCC_BAD_ACTION do { if (action == push) \
- GCC_BAD ("malformed '#pragma pack(push[, id], <n>)' -
ignored"); \
+#define GCC_BAD_ACTION do { if (action != pop) \
+ GCC_BAD ("malformed '#pragma pack(push[, id][, <n>])' -
ignored"); \
else \
GCC_BAD ("malformed '#pragma pack(pop[, id])' - ignored"); \
} while (0)
@@ -193,31 +175,21 @@
else
GCC_BAD2 ("unknown action '%s' for '#pragma pack' - ignored",
op);
- token = c_lex (&x);
- if (token != CPP_COMMA && action == push)
- GCC_BAD_ACTION;
-
- if (token == CPP_COMMA)
+ while ((token = c_lex (&x)) == CPP_COMMA)
{
token = c_lex (&x);
- if (token == CPP_NAME)
+ if (token == CPP_NAME && id == 0)
{
id = x;
- if (action == push && c_lex (&x) != CPP_COMMA)
- GCC_BAD_ACTION;
- token = c_lex (&x);
}
-
- if (action == push)
+ else if (token == CPP_NUMBER && action == push && align ==
-1)
{
- if (token == CPP_NUMBER)
- {
- align = TREE_INT_CST_LOW (x);
- token = c_lex (&x);
- }
- else
- GCC_BAD_ACTION;
+ align = TREE_INT_CST_LOW (x);
+ if (align == -1)
+ action = set;
}
+ else
+ GCC_BAD_ACTION;
}
if (token != CPP_CLOSE_PAREN)
@@ -230,6 +202,9 @@
if (c_lex (&x) != CPP_EOF)
warning ("junk at end of '#pragma pack'");
+ if (flag_pack_struct)
+ GCC_BAD ("#pragma pack has no effect with -fpack-struct -
ignored");
+
if (action != pop)
switch (align)
{
@@ -241,6 +216,12 @@
case 16:
align *= BITS_PER_UNIT;
break;
+ case -1:
+ if (action == push)
+ {
+ align = maximum_field_alignment;
+ break;
+ }
default:
GCC_BAD2 ("alignment must be a small power of two, not %d",
align);
}
@@ -268,7 +249,7 @@
value = build_string (IDENTIFIER_LENGTH (value),
IDENTIFIER_POINTER (value));
decl_attributes (&decl, build_tree_list (get_identifier
("alias"),
- build_tree_list (NULL,
value)),
+ build_tree_list (NULL,
value)),
0);
}
--- 3.4.0-base/gcc/opts.c 2004-02-18 01:09:04.000000000 +0100
+++ 3.4.0/gcc/opts.c 2004-05-06 13:43:56.926018224 +0200
@@ -1147,6 +1147,13 @@
flag_pack_struct = value;
break;
+ case OPT_fpack_struct_:
+ if (value <= 0 || (value & (value - 1)) || value > 16)
+ error("structure alignment must be a small power of two, not
%d", value);
+ else
+ maximum_field_alignment = initial_max_fld_align = value *
BITS_PER_UNIT;
+ break;
+
case OPT_fpeel_loops:
flag_peel_loops_set = true;
flag_peel_loops = value;
--- 3.4.0-base/gcc/tree.h 2004-02-08 02:52:43.000000000 +0100
+++ 3.4.0/gcc/tree.h 2004-05-03 13:38:03.000000000 +0200
@@ -2458,8 +2458,10 @@
+ (BITS_PER_UNIT > 8) + (BITS_PER_UNIT > 16) + (BITS_PER_UNIT > 32)
\
+ (BITS_PER_UNIT > 64) + (BITS_PER_UNIT > 128) + (BITS_PER_UNIT >
256))
-/* If nonzero, an upper limit on alignment of structure fields, in
bits. */
+/* If nonzero, an upper limit on alignment of structure fields, in
bits, */
extern unsigned int maximum_field_alignment;
+/* and the original value of it, specified via -fpack-struct=<value>.
*/
+extern unsigned int initial_max_fld_align;
/* If nonzero, the alignment of a bitstring or (power-)set value, in
bits. */
extern unsigned int set_alignment;
--- 3.4.0-base/gcc/stor-layout.c 2003-12-30 20:49:59.000000000
+0100
+++ 3.4.0/gcc/stor-layout.c 2004-05-03 13:38:03.000000000 +0200
@@ -48,7 +48,12 @@
/* If nonzero, this is an upper limit on alignment of structure
fields.
The value is measured in bits. */
-unsigned int maximum_field_alignment;
+#ifndef DEFAULT_PACK_STRUCT
+#define DEFAULT_PACK_STRUCT 0
+#endif
+unsigned int maximum_field_alignment = DEFAULT_PACK_STRUCT *
BITS_PER_UNIT;
+/* ... and the original value of it, specified via
-fpack-struct=<value>. */
+unsigned int initial_max_fld_align = DEFAULT_PACK_STRUCT *
BITS_PER_UNIT;
/* If nonzero, the alignment of a bitstring or (power-)set value, in
bits.
May be overridden by front-ends. */
--- 3.4.0-base/gcc/common.opt 2004-02-18 01:09:04.000000000 +0100
+++ 3.4.0/gcc/common.opt 2004-05-06 13:58:05.571004576 +0200
@@ -480,6 +480,10 @@
Common
Pack structure members together without holes
+fpack-struct=
+Common RejectNegative Joined UInteger
+-fpack-struct=<number> Set initial maximum structure member
alignment
+
fpcc-struct-return
Common
Return small aggregates in memory, not registers