[backport gcc-4.8/trunk r196458 <mikpe@it.uu.se>]

gcc/

2013-03-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56270
	* tree-vect-slp.c (vect_schedule_slp): Clear vectorized stmts
	of loads after scheduling an SLP instance.

gcc/testsuite/

2013-03-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/56270
	* gcc.dg/vect/slp-38.c: New testcase.

--- gcc-4.6.3/gcc/testsuite/gcc.dg/vect/slp-38.c.~1~	2013-03-09 15:25:17.290504655 +0100
+++ gcc-4.6.3/gcc/testsuite/gcc.dg/vect/slp-38.c	2013-03-09 15:25:17.290504655 +0100
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+
+typedef struct {
+    float l, h;
+} tFPinterval;
+
+tFPinterval X[1024];
+tFPinterval Y[1024];
+tFPinterval Z[1024];
+
+void Compute(void)
+{
+  int d;
+  for (d= 0; d < 1024; d++)
+    {
+      Y[d].l= X[d].l + X[d].h;
+      Y[d].h= Y[d].l;
+      Z[d].l= X[d].l;
+      Z[d].h= X[d].h;
+    }
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops in function" 1 "vect" { target { vect_float && vect_perm } } } } */
+/* { dg-final { cleanup-tree-dump "vect" } } */
--- gcc-4.6.3/gcc/tree-vect-slp.c.~1~	2010-12-23 17:25:52.000000000 +0100
+++ gcc-4.6.3/gcc/tree-vect-slp.c	2013-03-09 15:25:21.840485263 +0100
@@ -2532,7 +2532,8 @@ vect_schedule_slp (loop_vec_info loop_vi
 {
   VEC (slp_instance, heap) *slp_instances;
   slp_instance instance;
-  unsigned int i, vf;
+  slp_tree loads_node;
+  unsigned int i, j, vf;
   bool is_store = false;
 
   if (loop_vinfo)
@@ -2551,6 +2552,14 @@ vect_schedule_slp (loop_vec_info loop_vi
       /* Schedule the tree of INSTANCE.  */
       is_store = vect_schedule_slp_instance (SLP_INSTANCE_TREE (instance),
                                              instance, vf);
+
+      /* Clear STMT_VINFO_VEC_STMT of all loads.  With shared loads
+         between SLP instances we fail to properly initialize the
+	 vectorized SLP stmts and confuse different load permutations.  */
+      FOR_EACH_VEC_ELT (slp_tree, SLP_INSTANCE_LOADS (instance), j, loads_node)
+	STMT_VINFO_VEC_STMT
+	  (vinfo_for_stmt (VEC_index (gimple, SLP_TREE_SCALAR_STMTS (loads_node), 0))) = NULL;
+
       if (vect_print_dump_info (REPORT_VECTORIZED_LOCATIONS)
 	  || vect_print_dump_info (REPORT_UNVECTORIZED_LOCATIONS))
 	fprintf (vect_dump, "vectorizing stmts using SLP.");