We assume that all root stmts which compose the total reduction chain
are vectorized but fail to account for the cost of adding back the
scalar defs we are not vectorizing. The following rectifies this,
fixing the gcc.dg/tree-ssa/slsr-11.c FAIL on aarch64.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/111125
* tree-vect-slp.cc (vectorizable_bb_reduc_epilogue): Account
for the remain_defs processing.
---
gcc/tree-vect-slp.cc | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index cc799b6ebcd..ace0ff3ef60 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -6433,6 +6433,11 @@ vectorizable_bb_reduc_epilogue (slp_instance instance,
vectype, 0, vect_body);
record_stmt_cost (cost_vec, 1, vec_to_scalar, instance->root_stmts[0],
vectype, 0, vect_body);
+
+ /* Since we replace all stmts of a possibly longer scalar reduction
+ chain account for the extra scalar stmts for that. */
+ record_stmt_cost (cost_vec, instance->remain_defs.length (), scalar_stmt,
+ instance->root_stmts[0], 0, vect_body);
return true;
}
--
2.35.3
