https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122448
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2025-11-03
Ever confirmed|0 |1
Summary|Wrong rvv code with -O3 |[15 16 Regression] Wrong
| |rvv code with -O3
Status|UNCONFIRMED |NEW
CC| |rguenth at gcc dot gnu.org
--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Bisection landed on:
commit d93353e6423ecaaae9fa47d0935caafd9abfe4de
Author: Richard Biener <[email protected]>
Date: Fri Feb 23 11:45:50 2024 +0100
Do single-lane SLP discovery for reductions
The following performs single-lane SLP discovery for reductions.
It requires a fixup for outer loop vectorization where a check
for multiple types needs adjustments as otherwise bogus pointer
IV increments happen when there are multiple copies of vector stmts
in the inner loop.
For the reduction epilog handling this extends the optimized path
to cover the trivial single-lane SLP reduction case.
The fix for PR65518 implemented in vect_grouped_load_supported for
non-SLP needs a SLP counterpart that I put in get_group_load_store_type.
I've decided to adjust three testcases for appearing single-lane
SLP instances instead of not dumping "vectorizing stmts using SLP"
for single-lane instances as that also requires testsuite adjustments.
* tree-vect-slp.cc (vect_build_slp_tree_2): Only multi-lane
discoveries are reduction chains and need special backedge
treatment.
(vect_analyze_slp): Fall back to single-lane SLP discovery
for reductions. Make sure to try single-lane SLP reduction
for all reductions as fallback.
(vectorizable_load): Avoid outer loop SLP vectorization with
multi-copy vector stmts in the inner loop.
(vectorizable_store): Likewise.
* tree-vect-loop.cc (vect_create_epilog_for_reduction): Allow
direct opcode and shift reduction also for SLP reductions
with a single lane.
* tree-vect-stmts.cc (get_group_load_store_type): For SLP also
check for the PR65518 single-element interleaving case as done in
vect_grouped_load_supported.
* gcc.dg/vect/slp-24.c: Expect another SLP instance for the
reduction.
* gcc.dg/vect/slp-24-big-array.c: Likewise.
* gcc.dg/vect/slp-reduc-6.c: Remove scan for zero SLP instances.
