re PR middle-end/37042 (Strict-aliasing warnings are printed for _mm_load_si128,…

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

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

gcc/ChangeLog

+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 ...

gcc/testsuite/ChangeLog

+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 ...

gcc/testsuite/gcc.dg/Wstrict-aliasing-bogus-ref-all-2.c

+/* { 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;
+}
+

gcc/tree-ssa-alias-warnings.c

@@ -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.  */