On Wed, 2 Aug 2023 at 14:17, Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Mon, 31 Jul 2023, Jeff Law wrote:
>
> >
> >
> > On 7/28/23 01:05, Richard Biener via Gcc-patches wrote:
> > > The following delays sinking of loads within the same innermost
> > > loop when it was unconditional before. That's a not uncommon
> > > issue preventing vectorization when masked loads are not available.
> > >
> > > Bootstrapped and tested on x86_64-unknown-linux-gnu.
> > >
> > > I have a followup patch improving sinking that without this would
> > > cause more of the problematic sinking - now that we have a second
> > > sink pass after loop opts this looks like a reasonable approach?
> > >
> > > OK?
> > >
> > > Thanks,
> > > Richard.
> > >
> > > PR tree-optimization/92335
> > > * tree-ssa-sink.cc (select_best_block): Before loop
> > > optimizations avoid sinking unconditional loads/stores
> > > in innermost loops to conditional executed places.
> > >
> > > * gcc.dg/tree-ssa/ssa-sink-10.c: Disable vectorizing.
> > > * gcc.dg/tree-ssa/predcom-9.c: Clone from ssa-sink-10.c,
> > > expect predictive commoning to happen instead of sinking.
> > > * gcc.dg/vect/pr65947-3.c: Adjust.
> > I think it's reasonable -- there's probably going to be cases where it's not
> > great, but more often than not I think it's going to be a reasonable
> > heuristic.
> >
> > If there is undesirable fallout, better to find it over the coming months
> > than
> > next spring. So I'd suggest we go forward now to give more time to find any
> > pathological cases (if they exist).
>
> Agreed, I've pushed this now.
Hi Richard,
After this patch (committed in 399c8dd44ff44f4b496223c7cc980651c4d6f6a0),
pr65947-7.c "failed" for aarch64-linux-gnu:
FAIL: gcc.dg/vect/pr65947-7.c scan-tree-dump-not vect "LOOP VECTORIZED"
FAIL: gcc.dg/vect/pr65947-7.c -flto -ffat-lto-objects
scan-tree-dump-not vect "LOOP VECTORIZED"
/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" { target {
! vect_fold_extract_last } } } } */
With your commit, condition_reduction in pr65947-7.c gets vectorized
regardless of vect_fold_extract_last,
which gates the above test (which is an improvement, because the
function didn't get vectorized before the commit).
The attached patch thus removes the gating on vect_fold_extract_last,
and the test passes again.
OK to commit ?
Thanks,
Prathamesh
>
> Richard.
diff --git a/gcc/testsuite/gcc.dg/vect/pr65947-7.c
b/gcc/testsuite/gcc.dg/vect/pr65947-7.c
index 16cdcd1c6eb..7dabae81abf 100644
--- a/gcc/testsuite/gcc.dg/vect/pr65947-7.c
+++ b/gcc/testsuite/gcc.dg/vect/pr65947-7.c
@@ -52,5 +52,4 @@ main (void)
return 0;
}
-/* { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" { target
vect_fold_extract_last } } } */
-/* { dg-final { scan-tree-dump-not "LOOP VECTORIZED" "vect" { target { !
vect_fold_extract_last } } } } */
+/* { dg-final { scan-tree-dump "LOOP VECTORIZED" "vect" } } */
