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re PR middle-end/27945 (Packed struct of variable length has wrong size)

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PR middle-end/27945
        * stor-layout.c (layout_decl): Do pack variable size fields.

From-SVN: r128380
This commit is contained in:
Jason Merrill 2007-09-11 11:07:59 -04:00 • committed by Jason Merrill
parent 257fafe0c9
commit 7e4aeb3297
3 changed files with 39 additions and 11 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2007-09-11 Jason Merrill <jason@redhat.com>
PR middle-end/27945
* stor-layout.c (layout_decl): Do pack variable size fields.
2007-09-11 Maxim Kuvyrkov <maxim@codesourcery.com>
* config/m68k/predicates.md (movsi_const0_operand,

15
gcc/stor-layout.c
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@ -414,18 +414,11 @@ layout_decl (tree decl, unsigned int known_align)
else
do_type_align (type, decl);
/* If the field is of variable size, we can't misalign it since we
have no way to make a temporary to align the result. But this
isn't an issue if the decl is not addressable. Likewise if it
is of unknown size.
Note that do_type_align may set DECL_USER_ALIGN, so we need to
check old_user_align instead. */
/* If the field is packed and not explicitly aligned, give it the
minimum alignment. Note that do_type_align may set
DECL_USER_ALIGN, so we need to check old_user_align instead. */
if (packed_p
&& !old_user_align
&& (DECL_NONADDRESSABLE_P (decl)
|| DECL_SIZE_UNIT (decl) == 0
|| TREE_CODE (DECL_SIZE_UNIT (decl)) == INTEGER_CST))
&& !old_user_align)
DECL_ALIGN (decl) = MIN (DECL_ALIGN (decl), BITS_PER_UNIT);
if (! packed_p && ! DECL_USER_ALIGN (decl))

30
gcc/testsuite/gcc.dg/packed-vla.c Normal file
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@ -0,0 +1,30 @@
/* { dg-do run } */
/* { dg-options "" } */
extern int printf (const char *, ...);
extern void abort ();
int func(int levels)
{
struct bar {
unsigned char a;
int b[levels];
} __attribute__ ((__packed__)) bar;
struct foo {
unsigned char a;
int b[4];
} __attribute__ ((__packed__)) foo;
printf("foo %d\n", sizeof(foo));
printf("bar %d\n", sizeof(bar));
if (sizeof (foo) != sizeof (bar))
abort ();
}
int main()
{
func(4);
return 0;
}