On Mon, Feb 22, 2016 at 10:16 PM, Jakub Jelinek <ja...@redhat.com> wrote:
> Hi!
>
> On the following testcase, we ICE due to infinite recursion in decide_alg
> - max is 0, and expected_size is the same (2048) in the second and following
> recursive calls.
>
> Fixed by avoiding recursing with the same arguments as before.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2016-02-22 Jakub Jelinek <ja...@redhat.com>
>
> PR target/69888
> * config/i386/i386.c (decide_alg): Ensure we don't recurse with
> identical arguments. Formatting and spelling fixes.
>
> * gcc.target/i386/pr69888.c: New test.
OK with a nit below.
Thanks,
Uros.
>
> --- gcc/config/i386/i386.c.jj 2016-02-12 00:50:55.000000000 +0100
> +++ gcc/config/i386/i386.c 2016-02-22 10:25:53.564338145 +0100
> @@ -26032,11 +26032,12 @@ decide_alg (HOST_WIDE_INT count, HOST_WI
> bool memset, bool zero_memset, bool have_as,
> int *dynamic_check, bool *noalign)
> {
> - const struct stringop_algs * algs;
> + const struct stringop_algs *algs;
> bool optimize_for_speed;
> int max = 0;
> const struct processor_costs *cost;
> int i;
> + HOST_WIDE_INT orig_expected_size = expected_size;
> bool any_alg_usable_p = false;
>
> *noalign = false;
> @@ -26066,7 +26067,7 @@ decide_alg (HOST_WIDE_INT count, HOST_WI
> any_alg_usable_p |= usable;
>
> if (candidate != libcall && candidate && usable)
> - max = algs->size[i].max;
> + max = algs->size[i].max;
> }
>
> /* If expected size is not known but max size is small enough
> @@ -26076,7 +26077,7 @@ decide_alg (HOST_WIDE_INT count, HOST_WI
> && expected_size == -1)
> expected_size = min_size / 2 + max_size / 2;
>
> - /* If user specified the algorithm, honnor it if possible. */
> + /* If user specified the algorithm, honor it if possible. */
> if (ix86_stringop_alg != no_stringop
> && alg_usable_p (ix86_stringop_alg, memset, have_as))
> return ix86_stringop_alg;
> @@ -26152,20 +26153,20 @@ decide_alg (HOST_WIDE_INT count, HOST_WI
> || !alg_usable_p (algs->unknown_size, memset, have_as)))
> {
> enum stringop_alg alg;
> + HOST_WIDE_INT new_expected_size = (max > 0 ? max : 4096) / 2;
HOST_WIDE_INT new_expected_size = max > 0 ? max / 2 : 2048;
> - /* If there aren't any usable algorithms, then recursing on
> - smaller sizes isn't going to find anything. Just return the
> - simple byte-at-a-time copy loop. */
> - if (!any_alg_usable_p)
> + /* If there aren't any usable algorithms or if recursing with the
> + same arguments as before, then recursing on smaller sizes or
> + same size isn't going to find anything. Just return the simple
> + byte-at-a-time copy loop. */
> + if (!any_alg_usable_p || orig_expected_size == new_expected_size)
> {
> /* Pick something reasonable. */
> if (TARGET_INLINE_STRINGOPS_DYNAMICALLY)
> *dynamic_check = 128;
> return loop_1_byte;
> }
> - if (max <= 0)
> - max = 4096;
> - alg = decide_alg (count, max / 2, min_size, max_size, memset,
> + alg = decide_alg (count, new_expected_size, min_size, max_size, memset,
> zero_memset, have_as, dynamic_check, noalign);
> gcc_assert (*dynamic_check == -1);
> if (TARGET_INLINE_STRINGOPS_DYNAMICALLY)
> --- gcc/testsuite/gcc.target/i386/pr69888.c.jj 2016-02-22 10:31:52.529401396
> +0100
> +++ gcc/testsuite/gcc.target/i386/pr69888.c 2016-02-22 10:34:10.852502628
> +0100
> @@ -0,0 +1,10 @@
> +/* PR target/69888 */
> +/* { dg-do compile } */
> +/* { dg-options "-minline-all-stringops
> -mmemset-strategy=no_stringop:-1:noalign" } */
> +/* { dg-additional-options "-march=geode" { target ia32 } } */
> +
> +void
> +foo (char *p)
> +{
> + __builtin_memset (p, 0, 32);
> +}
>
> Jakub
