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authorRichard Biener <rguenther@suse.de>2024-01-17 14:05:42 +0100
committerRichard Biener <rguenther@suse.de>2024-01-18 08:31:41 +0100
commitb981d5c60b8ef78e2adecd6b5d7e36f9e5e61c54 (patch)
tree0370227d5c2ce54cf95261ab2592d6fd8a54290a /gcc
parent0f38666680d6ad0e40c4a8b6d94b2c93931cdf42 (diff)
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tree-optimization/113431 - wrong dependence with invariant load
The vectorizer dependence analysis is confused with invariant loads when figuring whether the circumstances are so that we preserve scalar stmt execution order. The following rectifies this. PR tree-optimization/113431 * tree-vect-data-refs.cc (vect_preserves_scalar_order_p): When there is an invariant load we might not preserve scalar order. * gcc.dg/vect/pr113431.c: New testcase.
Diffstat (limited to 'gcc')
-rw-r--r--gcc/testsuite/gcc.dg/vect/pr113431.c18
-rw-r--r--gcc/tree-vect-data-refs.cc6
2 files changed, 24 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/vect/pr113431.c b/gcc/testsuite/gcc.dg/vect/pr113431.c
new file mode 100644
index 0000000..04448d9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr113431.c
@@ -0,0 +1,18 @@
+/* { dg-additional-options "-O3 -fdump-tree-slp1-details" } */
+
+#include "tree-vect.h"
+
+int a[2][9];
+int b;
+int main()
+{
+ check_vect ();
+ for (b = 0; b < 2; b++)
+ for (long e = 8; e > 0; e--)
+ a[b][e] = a[0][1] == 0;
+ if (a[1][1] != 0)
+ __builtin_abort ();
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "optimized: basic block part vectorized" 2 "slp1" { target vect_int } } } */
diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
index 0495842..f592aeb 100644
--- a/gcc/tree-vect-data-refs.cc
+++ b/gcc/tree-vect-data-refs.cc
@@ -282,6 +282,12 @@ vect_preserves_scalar_order_p (dr_vec_info *dr_info_a, dr_vec_info *dr_info_b)
&& !STMT_VINFO_GROUPED_ACCESS (stmtinfo_b))
return true;
+ /* If there is a loop invariant read involved we might vectorize it in
+ the prologue, breaking scalar oder with respect to the in-loop store. */
+ if ((DR_IS_READ (dr_info_a->dr) && integer_zerop (DR_STEP (dr_info_a->dr)))
+ || (DR_IS_READ (dr_info_b->dr) && integer_zerop (DR_STEP (dr_info_b->dr))))
+ return false;
+
/* STMT_A and STMT_B belong to overlapping groups. All loads are
emitted at the position of the first scalar load.
Stores in a group are emitted at the position of the last scalar store.