From 898e3e95a6acf542baf03be95ce5bf7b3ad04276 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Mon, 9 Sep 2024 11:51:24 +0200
Subject: [PATCH] tree-optimization/116647 - wrong classified double reduction
The following avoids classifying a double reduction that's not
actually a reduction in the outer loop (because its value isn't
used outside of the outer loop). This avoids us ICEing on the
unexpected stmt/SLP node arrangement.
PR tree-optimization/116647
* tree-vect-loop.cc (vect_is_simple_reduction): Add missing
check to double reduction detection.
* gcc.dg/torture/pr116647.c: New testcase.
* gcc.dg/vect/no-scevccp-pr86725-2.c: Adjust expected pattern.
* gcc.dg/vect/no-scevccp-pr86725-4.c: Likewise.
---
gcc/testsuite/gcc.dg/torture/pr116647.c | 22 +++++++++++++++++++
.../gcc.dg/vect/no-scevccp-pr86725-2.c | 2 +-
.../gcc.dg/vect/no-scevccp-pr86725-4.c | 2 +-
gcc/tree-vect-loop.cc | 3 ++-
4 files changed, 26 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr116647.c
diff --git a/gcc/testsuite/gcc.dg/torture/pr116647.c b/gcc/testsuite/gcc.dg/torture/pr116647.c
new file mode 100644
index 000000000000..2b5cc3486900
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr116647.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+
+int a;
+char b;
+long c, d, e;
+unsigned long f;
+long g() {
+ if (a <= 0)
+ return 1;
+ for (; d; d++) {
+ e = 0;
+ for (; e < a; e++) {
+ unsigned long h = 0;
+ switch (b)
+ case 2:
+ if (e)
+ h = 5;
+ c += h;
+ }
+ }
+ c /= f;
+}
diff --git a/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-2.c b/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-2.c
index b208c1a2d615..66185a9483ba 100644
--- a/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-2.c
+++ b/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-2.c
@@ -19,5 +19,5 @@ nr (int xe)
return xe;
}
-/* { dg-final { scan-tree-dump "reduction used in loop" "vect" { target vect_int } } } */
+/* { dg-final { scan-tree-dump "Unknown def-use cycle pattern" "vect" { target vect_int } } } */
/* { dg-final { scan-tree-dump-not "OUTER LOOP VECTORIZED" "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-4.c b/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-4.c
index d995c9b30fe2..6ada0a10cb36 100644
--- a/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-4.c
+++ b/gcc/testsuite/gcc.dg/vect/no-scevccp-pr86725-4.c
@@ -19,5 +19,5 @@ nr (unsigned int xe, unsigned int qqn)
return xe;
}
-/* { dg-final { scan-tree-dump "reduction used in loop" "vect" { target vect_int } } } */
+/* { dg-final { scan-tree-dump "Unknown def-use cycle pattern" "vect" { target vect_int } } } */
/* { dg-final { scan-tree-dump-not "OUTER LOOP VECTORIZED" "vect" } } */
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index a879a13bbf0c..65d7ed51067e 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -4325,7 +4325,8 @@ vect_is_simple_reduction (loop_vec_info loop_info, stmt_vec_info phi_info,
&& is_a <gphi *> (phi_use_stmt)
&& flow_bb_inside_loop_p (loop->inner, gimple_bb (phi_use_stmt))
&& (op1 == PHI_ARG_DEF_FROM_EDGE (phi_use_stmt,
- loop_latch_edge (loop->inner))))
+ loop_latch_edge (loop->inner)))
+ && lcphis.length () == 1)
{
if (dump_enabled_p ())
report_vect_op (MSG_NOTE, def_stmt,
--
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