re PR tree-optimization/59354 (Element swizzling produces invalid result with -O3)

2015-01-14  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/59354
	* tree-vect-slp.c (vect_build_slp_tree_1): Treat loads from
	groups larger than the slp group size as having gaps.

	* gcc.dg/vect/pr59354.c: New testcase.

From-SVN: r219603

gcc/ChangeLog

+2015-01-14  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/59354
+	* tree-vect-slp.c (vect_build_slp_tree_1): Treat loads from
+	groups larger than the slp group size as having gaps.
+
 2015-01-14  Andrew MacLeod  <amacleod@redhat.com>
 
 	PR middle-end/59448

gcc/testsuite/ChangeLog

+2015-01-14  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/59354
+	* gcc.dg/vect/pr59354.c: New testcase.
+
 2015-01-14  Andrew Stubbs  <ams@codesourcery.com>
 
 	* lib/target-supports.exp

gcc/testsuite/gcc.dg/vect/pr59354.c

+/* { dg-do run } */
+/* { dg-additional-options "-O3" } */
+
+#include "tree-vect.h"
+
+void abort (void);
+
+unsigned int a[256];
+unsigned char b[256];
+
+int main()
+{
+  int i, z, x, y;
+
+  check_vect ();
+
+  for(i = 0; i < 256; i++)
+    {
+      a[i] = i % 5;
+      __asm__ volatile ("");
+    }
+
+  for (z = 0; z < 16; z++)
+    for (y = 0; y < 4; y++)
+      for (x = 0; x < 4; x++)
+	b[y*64 + z*4 + x] = a[z*16 + y*4 + x];
+
+  if (b[4] != 1)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "vectorized 1 loop" "vect" { target { vect_pack_trunc } } } } */
+/* { dg-final { cleanup-tree-dump "vect" } } */

gcc/tree-vect-slp.c

@@ -729,8 +729,11 @@ vect_build_slp_tree_1 (loop_vec_info loop_vinfo, bb_vec_info bb_vinfo,
 		 ???  We should enhance this to only disallow gaps
 		 inside vectors.  */
               if ((unrolling_factor > 1
-		   && GROUP_FIRST_ELEMENT (vinfo_for_stmt (stmt)) == stmt
-		   && GROUP_GAP (vinfo_for_stmt (stmt)) != 0)
+		   && ((GROUP_FIRST_ELEMENT (vinfo_for_stmt (stmt)) == stmt
+			&& GROUP_GAP (vinfo_for_stmt (stmt)) != 0)
+		       /* If the group is split up then GROUP_GAP
+			  isn't correct here, nor is GROUP_FIRST_ELEMENT.  */
+		       || GROUP_SIZE (vinfo_for_stmt (stmt)) > group_size))
 		  || (GROUP_FIRST_ELEMENT (vinfo_for_stmt (stmt)) != stmt
 		      && GROUP_GAP (vinfo_for_stmt (stmt)) != 1))
                 {