Add extra index check when merging VEC_CST, this handles the case when exactly
op1 needs to be return.
This fixes:
FAIL: gcc.dg/tree-ssa/forwprop-19.c scan-tree-dump-not forwprop1
"VEC_PERM_EXPR"
gcc/ChangeLog:
PR target/107220
* match.pd: Check the index of VEC_CST and return the op1 if needed.
---
gcc/match.pd | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/gcc/match.pd b/gcc/match.pd
index 3550c16aaa6..1efdc3abb5d 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -8106,6 +8106,7 @@ and,
vec_perm_builder builder0;
vec_perm_builder builder1;
vec_perm_builder builder2 (nelts, nelts, 1);
+ bool ident_to_1 = true;
if (!tree_to_vec_perm_builder (&builder0, @3)
|| !tree_to_vec_perm_builder (&builder1, @4))
@@ -8115,7 +8116,15 @@ and,
vec_perm_indices sel1 (builder1, 1, nelts);
for (int i = 0; i < nelts; i++)
- builder2.quick_push (sel0[sel1[i].to_constant ()]);
+ {
+ int tmp_index = sel0[sel1[i].to_constant ()].to_constant ();
+ builder2.quick_push (sel0[sel1[i].to_constant ()]);
+ if ( i != tmp_index)
+ ident_to_1 = false;
+ }
+
+ if (ident_to_1)
+ return @1;
vec_perm_indices sel2 (builder2, 2, nelts);
--
2.18.2
