https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70729
--- Comment #34 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
Thanks a lot Jakub for your detail comments.
I have simple fix which cures failures from 71734. The fix is simple
enough and simply check that the ref in problem belongs to simd loop:
diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index ee04826..c710bbe 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -2128,7 +2128,7 @@ ref_indep_loop_p_1 (struct loop *loop, im_mem_ref *ref,
if (bitmap_bit_p (refs_to_check, UNANALYZABLE_MEM_ID))
return false;
- if (loop->safelen > 0)
+ if (loop->safelen > 1 && bitmap_bit_p (refs_to_check, ref->id))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
and I checked that simd3.f90 and simd4.f90 from libgomp.fortran passed with it.
2016-07-04 18:30 GMT+03:00 jakub at gcc dot gnu.org <gcc-bugzi...@gcc.gnu.org>:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70729
>
> --- Comment #33 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
> In any case, loop->safelen > 0 test looks also wrong, if there are guarantees
> about single iteration only (safelen(1)), then there is nothing useful at all.
> So it must be loop->safelen >= 2.
>
> For foo in #c29, the q[0] load in foo can be hoisted before the loop.
> More complicated is e.g.:
> void baz (int *p, int *q, int *r, int *s)
> {
> #pragma omp simd
> for (int i = 0; i < 1024; i++)
> {
> p[i] += q[0] * 6;
> r[i] += s[0] * 9;
> }
> }
> Here IMNSHO only q[0] * 6 can be hoisted before the loop, while it can alias
> p[1023] (or for x < 1023 p[x] if p[x] is initially 0), p[1023] could validly
> alias s[0] and thus s[0] * 9 must not be hoisted.
>
> --
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