From f7dad9af02c21ad7f0b6d01ffecc0b7d1a6b03ed Mon Sep 17 00:00:00 2001
From: rguenth <rguenth@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 18 May 2011 13:24:05 +0000
Subject: [PATCH] 2011-05-18  Richard Guenther  <rguenther@suse.de>

        Backport from mainline
        2011-05-12  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/48172
        * tree-vect-loop-manip.c (vect_vfa_segment_size): Do not exclude
        the number of iterations from the segment size calculation.
        (vect_create_cond_for_alias_checks): Adjust.

        2011-05-13  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/48172
        * tree-vect-loop-manip.c (vect_vfa_segment_size): Avoid
        multiplying by number of iterations for equal step.
        (vect_create_cond_for_alias_checks): Likewise.

        * gcc.dg/vect/pr48172.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_6-branch@173859 138bc75d-0d04-0410-961f-82ee72b054a4

index d3585ce..28581a0 100644
new file mode 100644
index 0000000..892aeca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr48172.c
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+
+extern void *memset(void *s, int c, __SIZE_TYPE__ n);
+extern void abort (void);
+
+#define ASIZE 1028
+#define HALF (ASIZE/2)
+
+int main() {
+  unsigned int array[ASIZE];
+  int i;
+
+  memset(array, 0, sizeof(array));
+
+  /* initialize first half of the array */
+  for (i = 0; i < HALF; i++)
+    array[i] = i;
+
+  /* fill second half of array in by summing earlier elements of the array
+     gcc 4.5.1 and 4.5.2 incorrectly vectorize this loop!  aray[1025] is left
+     at 0 for ASIZE=1028 */
+  for (i = 0; i < HALF-1; i++)
+    array[HALF+i] = array[2*i] + array[2*i + 1];
+
+  /* see if we have any failures */
+  for (i = 0; i < HALF - 1; i++)
+    if (array[HALF+i] != array[2*i] + array[2*i + 1])
+      abort ();
+
+  return 0;
+}
+
+/* { dg-final { cleanup-tree-dump "vect" } } */
diff --git a/gcc/tree-vect-loop-manip.c b/gcc/tree-vect-loop-manip.c
index 28b75f1..b691cd2 100644
--- a/gcc/tree-vect-loop-manip.c
+++ b/gcc/tree-vect-loop-manip.c
@@ -2353,27 +2353,27 @@ vect_create_cond_for_align_checks (loop_vec_info loop_vinfo,
 
    Input:
      DR: The data reference.
-     VECT_FACTOR: vectorization factor.
+     LENGTH_FACTOR: segment length to consider.
 
    Return an expression whose value is the size of segment which will be
    accessed by DR.  */
 
 static tree
-vect_vfa_segment_size (struct data_reference *dr, tree vect_factor)
+vect_vfa_segment_size (struct data_reference *dr, tree length_factor)
 {
-  tree segment_length = fold_build2 (MULT_EXPR, integer_type_node,
-			             DR_STEP (dr), vect_factor);
-
+  tree segment_length;
+  segment_length = size_binop (MULT_EXPR,
+			       fold_convert (sizetype, DR_STEP (dr)),
+			       fold_convert (sizetype, length_factor));
   if (vect_supportable_dr_alignment (dr, false)
         == dr_explicit_realign_optimized)
     {
       tree vector_size = TYPE_SIZE_UNIT
 			  (STMT_VINFO_VECTYPE (vinfo_for_stmt (DR_STMT (dr))));
 
-      segment_length = fold_build2 (PLUS_EXPR, integer_type_node,
-				    segment_length, vector_size);
+      segment_length = size_binop (PLUS_EXPR, segment_length, vector_size);
     }
-  return fold_convert (sizetype, segment_length);
+  return segment_length;
 }
 
 
@@ -2407,12 +2407,12 @@ vect_create_cond_for_alias_checks (loop_vec_info loop_vinfo,
   struct loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
   VEC (ddr_p, heap) * may_alias_ddrs =
     LOOP_VINFO_MAY_ALIAS_DDRS (loop_vinfo);
-  tree vect_factor =
-    build_int_cst (integer_type_node, LOOP_VINFO_VECT_FACTOR (loop_vinfo));
+  int vect_factor = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
+  tree scalar_loop_iters = LOOP_VINFO_NITERS (loop_vinfo);
 
   ddr_p ddr;
   unsigned int i;
-  tree part_cond_expr;
+  tree part_cond_expr, length_factor;
 
   /* Create expression
      ((store_ptr_0 + store_segment_length_0) < load_ptr_0)
@@ -2460,8 +2460,12 @@ vect_create_cond_for_alias_checks (loop_vec_info loop_vinfo,
         vect_create_addr_base_for_vector_ref (stmt_b, cond_expr_stmt_list,
 					      NULL_TREE, loop);
 
-      segment_length_a = vect_vfa_segment_size (dr_a, vect_factor);
-      segment_length_b = vect_vfa_segment_size (dr_b, vect_factor);
+      if (!operand_equal_p (DR_STEP (dr_a), DR_STEP (dr_b), 0))
+	length_factor = scalar_loop_iters;
+      else
+	length_factor = size_int (vect_factor);
+      segment_length_a = vect_vfa_segment_size (dr_a, length_factor);
+      segment_length_b = vect_vfa_segment_size (dr_b, length_factor);
 
       if (vect_print_dump_info (REPORT_DR_DETAILS))
 	{
-- 
1.7.0.4