This should preserve the original association order as much as possible
for the initial SLP discovery attempt and also improve consistency.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
2021-06-11 Richard Biener <rguent...@suse.de>
* tree-vect-slp.c (vect_build_slp_tree_2): Use stablesort
to sort operands of the associative chain.
---
gcc/tree-vect-slp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index c4f8f38012f..6237a61ffd4 100644
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -1865,7 +1865,7 @@ vect_build_slp_tree_2 (vec_info *vinfo, slp_tree node,
/* Now we have a set of chains with the same length. */
/* 1. pre-sort according to def_type and operation. */
for (unsigned lane = 0; lane < group_size; ++lane)
- chains[lane].sort (dt_sort_cmp, vinfo);
+ chains[lane].stablesort (dt_sort_cmp, vinfo);
if (dump_enabled_p ())
{
dump_printf_loc (MSG_NOTE, vect_location,
--
2.26.2
