https://gcc.gnu.org/g:0f86e86a869a7defefa63469a1c411ab4bb36c25
commit r13-9509-g0f86e86a869a7defefa63469a1c411ab4bb36c25
Author: Richard Biener <rguent...@suse.de>
Date: Tue Jan 28 15:01:25 2025 +0100
tree-optimization/112859 - add comment
This adds a comment before the workaround, indicating flaky
dependence analysis.
PR tree-optimization/112859
* tree-loop-distribution.cc
(loop_distribution::pg_add_dependence_edges): Add comment.
(cherry picked from commit 3ccbc8c9d182c380e396631b2b5a683de4fddba9)
Diff:
---
gcc/tree-loop-distribution.cc | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-loop-distribution.cc b/gcc/tree-loop-distribution.cc
index 66474c495d59..3beffaf92c5d 100644
--- a/gcc/tree-loop-distribution.cc
+++ b/gcc/tree-loop-distribution.cc
@@ -2178,7 +2178,9 @@ loop_distribution::pg_add_dependence_edges (struct graph
*rdg, int dir,
this_dir = -this_dir;
}
/* When then dependence distance of the innermost common
- loop of the DRs is zero we have a conflict. */
+ loop of the DRs is zero we have a conflict. This is
+ due to wonky dependence analysis which sometimes
+ ends up using a zero distance in place of unknown. */
auto l1 = gimple_bb (DR_STMT (dr1))->loop_father;
auto l2 = gimple_bb (DR_STMT (dr2))->loop_father;
int idx = index_in_loop_nest (find_common_loop (l1, l2)->num,
