re PR tree-optimization/54132 (Incorrect loop transformation with -ftree-loop-distribute-patterns)

2012-09-19  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/54132
	* tree-loop-distribution.c (classify_partition): Properly
	check dependences for memmove.
	* tree-data-ref.h (compute_affine_dependence): Declare.
	* tree-data-ref.c (compute_affine_dependence): Export.

	* gcc.dg/tree-ssa/ldist-21.c: New testcase.
	* gcc.dg/torture/pr54132.c: Likewise.

From-SVN: r191463

1 files changed, 33 insertions, 0 deletions

diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c
index f340eab..b24af33 100644
--- a/gcc/tree-loop-distribution.c
+++ b/gcc/tree-loop-distribution.c
@@ -1011,6 +1011,39 @@ classify_partition (loop_p loop, struct graph *rdg, partition_t partition)
 	  || !operand_equal_p (DR_STEP (single_store),
 			       DR_STEP (single_load), 0))
 	return;
+      /* Now check that if there is a dependence this dependence is
+         of a suitable form for memmove.  */
+      VEC(loop_p, heap) *loops = NULL;
+      ddr_p ddr;
+      VEC_safe_push (loop_p, heap, loops, loop);
+      ddr = initialize_data_dependence_relation (single_load, single_store,
+						 loops);
+      compute_affine_dependence (ddr, loop);
+      VEC_free (loop_p, heap, loops);
+      if (DDR_ARE_DEPENDENT (ddr) == chrec_dont_know)
+	{
+	  free_dependence_relation (ddr);
+	  return;
+	}
+      if (DDR_ARE_DEPENDENT (ddr) != chrec_known)
+	{
+	  if (DDR_NUM_DIST_VECTS (ddr) == 0)
+	    {
+	      free_dependence_relation (ddr);
+	      return;
+	    }
+	  lambda_vector dist_v;
+	  FOR_EACH_VEC_ELT (lambda_vector, DDR_DIST_VECTS (ddr), i, dist_v)
+	    {
+	      int dist = dist_v[index_in_loop_nest (loop->num,
+						    DDR_LOOP_NEST (ddr))];
+	      if (dist > 0 && !DDR_REVERSED_P (ddr))
+		{
+		  free_dependence_relation (ddr);
+		  return;
+		}
+	    }
+	}
       partition->kind = PKIND_MEMCPY;
       partition->main_dr = single_store;
       partition->secondary_dr = single_load;