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re PR middle-end/37042 (Strict-aliasing warnings are printed for _mm_load_si128, even though __m128i is __attribute__((__may_alias__)).)

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2008-08-07  Richard Guenther  <rguenther@suse.de>

	PR middle-end/37042
	* tree-ssa-alias-warnings.c (nonstandard_alias_p): Ref-all
	pointers can access anything.

	* gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c: New testcase.

From-SVN: r138837
This commit is contained in:
Richard Guenther 2008-08-07 10:01:48 +00:00 • committed by Richard Biener
parent 18bd082d90
commit 9aa4d3c1cb
4 changed files with 39 additions and 0 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2008-08-07 Richard Guenther <rguenther@suse.de>
PR middle-end/37042
* tree-ssa-alias-warnings.c (nonstandard_alias_p): Ref-all
pointers can access anything.
2008-08-06 Jan Hubicka <jh@suse.cz>
* optabs.c (emit_unop_insn): Break out to ...

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2008-08-07 Richard Guenther <rguenther@suse.de>
PR middle-end/37042
* gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c: New testcase.
2008-08-07 Andreas Krebbel <krebbel1@de.ibm.com>
* gcc.c-torture/compile/20080806-1.c: Move testcase ...

24
gcc/testsuite/gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c Normal file
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@ -0,0 +1,24 @@
/* { dg-do compile } */
/* { dg-options "-O2 -Wall" } */
typedef long long __m128i __attribute__ ((__vector_size__ (16), __may_alias__));
extern __inline __m128i __attribute__((__gnu_inline__, __always_inline__, __artificial__))
_mm_load_si128 (__m128i const *__P)
{
return *__P;
}
static const short __attribute__((__aligned__(16))) tbl[8] =
{ 1, 2, 3, 4, 5, 6, 7, 8};
__m128i get_vec(void)
{
__m128i ret;
ret = _mm_load_si128((__m128i *)tbl); /* { dg-bogus "type-punning" } */
return ret;
}

4
gcc/tree-ssa-alias-warnings.c
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@ -889,6 +889,10 @@ nonstandard_alias_p (tree ptr, tree alias, bool ptr_ptr)
tree ptr_type = get_otype (ptr, true);
tree alias_type = get_otype (alias, ptr_ptr);
/* If this is a ref-all pointer the access is ok. */
if (TYPE_REF_CAN_ALIAS_ALL (TREE_TYPE (ptr)))
return false;
/* XXX: for now, say it's OK if the alias escapes.
Not sure this is needed in general, but otherwise GCC will not
bootstrap. */