diff mbox series

tree-optimization/116647 - wrong classified double reduction

Message ID 20240909105941.1846B3858432@sourceware.org
State New
Headers show
Series tree-optimization/116647 - wrong classified double reduction | expand

Commit Message

Richard Biener Sept. 9, 2024, 10:59 a.m. UTC 
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.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	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 mbox series

Patch

diff --git a/gcc/testsuite/gcc.dg/torture/pr116647.c b/gcc/testsuite/gcc.dg/torture/pr116647.c
new file mode 100644
index 00000000000..2b5cc348690
--- /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 b208c1a2d61..66185a9483b 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 d995c9b30fe..6ada0a10cb3 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 e45adbaccbd..77486183a64 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -4342,7 +4342,8 @@  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,