https://gcc.gnu.org/g:28edeb1409a7b839407ec06031899b933390bff3
commit r15-1053-g28edeb1409a7b839407ec06031899b933390bff3 Author: Richard Biener <rguent...@suse.de> Date: Fri Feb 23 16:16:38 2024 +0100 Relax COND_EXPR reduction vectorization SLP restriction Allow one-lane SLP but for the case where we need to swap the arms. * tree-vect-stmts.cc (vectorizable_condition): Allow single-lane SLP, but not when we need to swap then and else clause. Diff: --- gcc/tree-vect-stmts.cc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc index b26cc74f417..c82381e799e 100644 --- a/gcc/tree-vect-stmts.cc +++ b/gcc/tree-vect-stmts.cc @@ -12116,7 +12116,7 @@ vectorizable_condition (vec_info *vinfo, = STMT_VINFO_REDUC_DEF (vect_orig_stmt (stmt_info)) != NULL; if (for_reduction) { - if (slp_node) + if (slp_node && SLP_TREE_LANES (slp_node) > 1) return false; reduc_info = info_for_reduction (vinfo, stmt_info); reduction_type = STMT_VINFO_REDUC_TYPE (reduc_info); @@ -12205,6 +12205,10 @@ vectorizable_condition (vec_info *vinfo, cond_expr = NULL_TREE; } } + /* ??? The vectorized operand query below doesn't allow swapping + this way for SLP. */ + if (slp_node) + return false; std::swap (then_clause, else_clause); }