diff mbox

Fix PR63379

Message ID alpine.LSU.2.11.1410091100040.20733@zhemvz.fhfr.qr
State New
Headers show

Commit Message

Richard Biener Oct. 9, 2014, 9:01 a.m. UTC 
This fixes SLP vectorization of a MIN/MAX reduction where we choose
a "neutral" element as the initial value of the first SLP group
member.  That's of course wrong.  Simply don't choose one in which
case the proper initial values will used.

Bootstrap / regtest running on x86_64-unknown-linux-gnu.

Richard.

2014-10-09  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/63379
	* tree-vect-slp.c (vect_get_constant_vectors): Do not compute
	a neutral operand for min/max.

	* gcc.dg/vect/pr63379.c: New testcase.
diff mbox

Patch

Index: gcc/tree-vect-slp.c
===================================================================
--- gcc/tree-vect-slp.c	(revision 215917)
+++ gcc/tree-vect-slp.c	(working copy)
@@ -2395,13 +2395,8 @@  vect_get_constant_vectors (tree op, slp_
             neutral_op = build_int_cst (TREE_TYPE (op), -1);
             break;
 
-          case MAX_EXPR:
-          case MIN_EXPR:
-            def_stmt = SSA_NAME_DEF_STMT (op);
-            loop = (gimple_bb (stmt))->loop_father;
-            neutral_op = PHI_ARG_DEF_FROM_EDGE (def_stmt,
-                                                loop_preheader_edge (loop));
-            break;
+	  /* For MIN/MAX we don't have an easy neutral operand but
+	     the initial values can be used fine here.  */
 
           default:
             neutral_op = NULL;
Index: gcc/testsuite/gcc.dg/vect/pr63379.c
===================================================================
--- gcc/testsuite/gcc.dg/vect/pr63379.c	(revision 0)
+++ gcc/testsuite/gcc.dg/vect/pr63379.c	(working copy)
@@ -0,0 +1,43 @@ 
+/* PR tree-optimization/63379  */
+/* { dg-do run } */
+
+#include "tree-vect.h"
+
+extern void abort (void);
+
+typedef struct {
+    int x;
+    int y;
+} Point;
+
+Point pt_array[25];
+
+void __attribute__((noinline,noclone))
+generate_array(void)
+{
+  unsigned int i;
+  for (i = 0; i<25; i++)
+    {
+      pt_array[i].x = i;
+      pt_array[i].y = 1000+i;
+    }
+}
+
+int main()
+{
+  check_vect ();
+  generate_array ();
+  Point min_pt = pt_array[0];
+  Point *ptr, *ptr_end;
+  for (ptr = pt_array+1, ptr_end = pt_array+25; ptr != ptr_end; ++ptr)
+    {
+      min_pt.x = (min_pt.x < ptr->x) ? min_pt.x : ptr->x;
+      min_pt.y = (min_pt.y < ptr->y) ? min_pt.y : ptr->y;
+    }
+
+  if (min_pt.x != 0 || min_pt.y != 1000)
+    abort ();
+  return 0;
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */