The following makes sure to reduce a multi-vector SLP reduction
accumulator to a single vector using vector operations if
easily possible (if the number of lanes in the vector type is
a multiple of the number of scalar accumulators).
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
PR tree-optimization/107247
* tree-vect-loop.cc (vect_create_epilog_for_reduction):
Reduce multi vector SLP reduction accumulators. Check
the adjusted number of accumulator vectors against
one for the re-use in the epilogue.
---
gcc/tree-vect-loop.cc | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index b1442a93581..98a943d8a4b 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -5642,9 +5642,21 @@ vect_create_epilog_for_reduction (loop_vec_info
loop_vinfo,
we may end up with more than one vector result. Here we reduce them
to one vector.
+ The same is true for a SLP reduction, e.g.,
+ # a1 = phi <a2, a0>
+ # b1 = phi <b2, b0>
+ a2 = operation (a1)
+ b2 = operation (a2),
+
+ where we can end up with more than one vector as well. We can
+ easily accumulate vectors when the number of vector elements is
+ a multiple of the SLP group size.
+
The same is true if we couldn't use a single defuse cycle. */
if (REDUC_GROUP_FIRST_ELEMENT (stmt_info)
|| direct_slp_reduc
+ || (slp_reduc
+ && constant_multiple_p (TYPE_VECTOR_SUBPARTS (vectype), group_size))
|| ncopies > 1)
{
gimple_seq stmts = NULL;
@@ -6233,7 +6245,7 @@ vect_create_epilog_for_reduction (loop_vec_info
loop_vinfo,
/* Record this operation if it could be reused by the epilogue loop. */
if (STMT_VINFO_REDUC_TYPE (reduc_info) == TREE_CODE_REDUCTION
- && vec_num == 1)
+ && reduc_inputs.length () == 1)
loop_vinfo->reusable_accumulators.put (scalar_results[0],
{ orig_reduc_input, reduc_info });
--
2.35.3
