On Thu, 27 Feb 2020, Jakub Jelinek wrote:
> Hi!
>
> And here is the corresponding 9.x change where we the patch just punts if
> ref->size is not whole bytes, like we already punt if offseti is not byte
> aligned.
>
> Tested on x86_64-linux and powerpc64-linux, ok for 9.3?
OK.
Thanks,
Richard.
> 2020-02-27 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/93945
> * tree-ssa-sccvn.c (vn_reference_lookup_3): For memset with non-zero
> second operand, require ref->size to be a multiple of BITS_PER_UNIT.
>
> * gcc.c-torture/execute/pr93945.c: New test.
>
> --- gcc/tree-ssa-sccvn.c.jj 2020-01-12 12:17:01.031158921 +0100
> +++ gcc/tree-ssa-sccvn.c 2020-02-27 10:55:16.226236453 +0100
> @@ -2113,7 +2113,8 @@ vn_reference_lookup_3 (ao_ref *ref, tree
> || (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8)))
> && CHAR_BIT == 8 && BITS_PER_UNIT == 8
> && offset.is_constant (&offseti)
> - && offseti % BITS_PER_UNIT == 0))
> + && offseti % BITS_PER_UNIT == 0
> + && multiple_p (ref->size, BITS_PER_UNIT)))
> && poly_int_tree_p (gimple_call_arg (def_stmt, 2))
> && (TREE_CODE (gimple_call_arg (def_stmt, 0)) == ADDR_EXPR
> || TREE_CODE (gimple_call_arg (def_stmt, 0)) == SSA_NAME))
> --- gcc/testsuite/gcc.c-torture/execute/pr93945.c.jj 2020-02-27
> 10:54:21.234060635 +0100
> +++ gcc/testsuite/gcc.c-torture/execute/pr93945.c 2020-02-27
> 10:54:21.234060635 +0100
> @@ -0,0 +1,45 @@
> +/* PR tree-optimization/93945 */
> +
> +union U { char a[8]; struct S { unsigned int b : 8, c : 13, d : 11; } e; } u;
> +
> +__attribute__((noipa)) int
> +foo (void)
> +{
> + __builtin_memset (&u.a, 0xf4, sizeof (u.a));
> + return u.e.c;
> +}
> +
> +__attribute__((noipa)) int
> +bar (void)
> +{
> + asm volatile ("" : : "g" (&u) : "memory");
> + return u.e.c;
> +}
> +
> +__attribute__((noipa)) int
> +baz (void)
> +{
> + __builtin_memset (&u.a, 0xf4, sizeof (u.a));
> + return u.e.d;
> +}
> +
> +__attribute__((noipa)) int
> +qux (void)
> +{
> + asm volatile ("" : : "g" (&u) : "memory");
> + return u.e.d;
> +}
> +
> +int
> +main ()
> +{
> + int a = foo ();
> + int b = bar ();
> + if (a != b)
> + __builtin_abort ();
> + a = baz ();
> + b = qux ();
> + if (a != b)
> + __builtin_abort ();
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
