https://gcc.gnu.org/g:882f7e53a7664f2c76b10dc020e720ba9f55f022
commit r12-10894-g882f7e53a7664f2c76b10dc020e720ba9f55f022
Author: Richard Biener <rguent...@suse.de>
Date: Thu Jun 27 11:26:08 2024 +0200
tree-optimization/115669 - fix SLP reduction association
The following avoids associating a reduction path as that might
get STMT_VINFO_REDUC_IDX out-of-sync with the SLP operand order.
This is a latent issue with SLP reductions but now easily exposed
as we're doing single-lane SLP reductions.
When we achieved SLP only we can move and update this meta-data.
PR tree-optimization/115669
* tree-vect-slp.cc (vect_build_slp_tree_2): Do not reassociate
chains that participate in a reduction.
* gcc.dg/vect/pr115669.c: New testcase.
(cherry picked from commit 7886830bb45c4f5dca0496d4deae9a45204d78f5)
Diff:
---
gcc/testsuite/gcc.dg/vect/pr115669.c | 22 ++++++++++++++++++++++
gcc/tree-vect-slp.cc | 3 +++
2 files changed, 25 insertions(+)
diff --git a/gcc/testsuite/gcc.dg/vect/pr115669.c
b/gcc/testsuite/gcc.dg/vect/pr115669.c
new file mode 100644
index 000000000000..361a17a64e68
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr115669.c
@@ -0,0 +1,22 @@
+/* { dg-additional-options "-fwrapv" } */
+
+#include "tree-vect.h"
+
+int a = 10;
+unsigned b;
+long long c[100];
+int foo()
+{
+ long long *d = c;
+ for (short e = 0; e < a; e++)
+ b += ~(d ? d[e] : 0);
+ return b;
+}
+
+int main()
+{
+ check_vect ();
+ if (foo () != -10)
+ abort ();
+ return 0;
+}
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 19cab93761c9..0462fa01020d 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -1825,6 +1825,9 @@ vect_build_slp_tree_2 (vec_info *vinfo, slp_tree node,
else if (is_a <loop_vec_info> (vinfo)
/* ??? We don't handle !vect_internal_def defs below. */
&& STMT_VINFO_DEF_TYPE (stmt_info) == vect_internal_def
+ /* ??? Do not associate a reduction, this will wreck REDUC_IDX
+ mapping as long as that exists on the stmt_info level. */
+ && STMT_VINFO_REDUC_IDX (stmt_info) == -1
&& is_gimple_assign (stmt_info->stmt)
&& (associative_tree_code (gimple_assign_rhs_code (stmt_info->stmt))
|| gimple_assign_rhs_code (stmt_info->stmt) == MINUS_EXPR)
