PATCH: ICE: SIGSEGV in decide_alg() with -mmemset-strategy=libcall:-1:align -minline-all-stringops

[H.J. Lu]

On Sat, Nov 29, 2014 at 6:00 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> When searching for an usable algorithm with -minline-all-stringops,
> decide_alg stops when it sees libcall even if there is a usable
> algorithm.  It goes into an infinite loop.  This patch changes
> decide_alg to stop searching only if there aren't any usable algorithms.
> Testd on Linux/x86-64.  OK for trunk.

The bug is also in GCC 4.9.  OK for backport?

>
> H.J.
> ----
> gcc/
>
> 2014-11-29  H.J. Lu  <hongjiu.lu@intel.com>
>
>         PR target/64108
>         * config/i386/i386.c (decide_alg): Stop only if there aren't
>         any usable algorithms.
>
> gcc/testsuite/
>
> 2014-11-29  H.J. Lu  <hongjiu.lu@intel.com>
>
>         PR target/64108
>         * gcc.target/i386/memset-strategy-2.c: New test.
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 2493130..d789635 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -24464,7 +24464,9 @@ decide_alg (HOST_WIDE_INT count, HOST_WIDE_INT expected_size,
>                       *noalign = alg_noalign;
>                       return alg;
>                     }
> -                 break;
> +                 /* Stop only if there aren't any usable algorithms.  */
> +                 if (!any_alg_usable_p)
> +                   break;
>                 }
>               else if (alg_usable_p (candidate, memset))
>                 {
> diff --git a/gcc/testsuite/gcc.target/i386/memset-strategy-2.c b/gcc/testsuite/gcc.target/i386/memset-strategy-2.c
> new file mode 100644
> index 0000000..aafa54d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/memset-strategy-2.c
> @@ -0,0 +1,10 @@
> +/* PR target/64108 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -march=atom -mmemset-strategy=libcall:-1:align -minline-all-stringops" } */
> +
> +char a[2048];
> +void t (void)
> +{
> +  __builtin_memset (a, 1, 2048);
> +}
> +



-- 
H.J.