On Sat, Nov 29, 2014 at 3:00 PM, H.J. Lu <hjl.to...@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.
>
>
> H.J.
> ----
> gcc/
>
> 2014-11-29 H.J. Lu <hongjiu...@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...@intel.com>
>
> PR target/64108
> * gcc.target/i386/memset-strategy-2.c: New test.
OK with a change below. Please wait a couple of days before
backporting the fix - the fix looks kind of obvious, but this part of
the code is somehow complex and has biten us in the past.
Thanks,
Uros.
> 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;
Please use "else if ..." and remove unneded argument. IMO, the code
speaks for itself.
> }
> 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);
> +}
> +
