From ae156936cf4f15d9cc2b7d4e39f2e6b8fe22a9c3 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Tue, 21 Nov 2023 09:50:54 +0100 Subject: [PATCH] Move VF based dependence check The following moves the check whether the maximum vectorization factor determined by data dependence analysis is in conflict with the chosen vectorization factor to after the point where we applied both the SLP and the unrolling adjustment to the vectorization factor. We check the latter before applying unrolling, but the SLP adjustment can result in both missed optimization and wrong-code. * tree-vect-loop.cc (vect_analyze_loop_2): Move check of VF against max_vf until VF is final. --- gcc/tree-vect-loop.cc | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc index 58679e91c0aa..a73a533beb1b 100644 --- a/gcc/tree-vect-loop.cc +++ b/gcc/tree-vect-loop.cc @@ -2817,9 +2817,6 @@ vect_analyze_loop_2 (loop_vec_info loop_vinfo, bool &fatal, "can't determine vectorization factor.\n"); return ok; } - if (max_vf != MAX_VECTORIZATION_FACTOR - && maybe_lt (max_vf, LOOP_VINFO_VECT_FACTOR (loop_vinfo))) - return opt_result::failure_at (vect_location, "bad data dependence.\n"); /* Compute the scalar iteration cost. */ vect_compute_single_scalar_iteration_cost (loop_vinfo); @@ -2881,6 +2878,10 @@ start_over: LOOP_VINFO_INT_NITERS (loop_vinfo)); } + if (max_vf != MAX_VECTORIZATION_FACTOR + && maybe_lt (max_vf, LOOP_VINFO_VECT_FACTOR (loop_vinfo))) + return opt_result::failure_at (vect_location, "bad data dependence.\n"); + loop_vinfo->vector_costs = init_cost (loop_vinfo, false); /* Analyze the alignment of the data-refs in the loop. -- 2.47.2