tree-ssa-sccvn.c (vn_reference_lookup_3): Remove restriction of fixed offset from memset VN.

2018-05-23  Richard Biener  <rguenther@suse.de>

	* tree-ssa-sccvn.c (vn_reference_lookup_3): Remove restriction
	of fixed offset from memset VN.

	* gcc.dg/tree-ssa/ssa-fre-66.c: New testcase.

From-SVN: r260609

gcc/ChangeLog

+2018-05-23  Richard Biener  <rguenther@suse.de>
+
+	* tree-ssa-sccvn.c (vn_reference_lookup_3): Remove restriction
+	of fixed offset from memset VN.
+
 2018-05-23  Bill Schmidt  <wschmidt@linux.ibm.com>
 
 	* gimple-ssa-strength-reduction.c (struct slsr_cand_d): Add

gcc/testsuite/ChangeLog

+2018-05-23  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/ssa-fre-66.c: New testcase.
+
 2018-05-23  Sudakshina Das  <sudi.das@arm.com>
 
 	PR target/84882

gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-66.c

+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-fre1" } */
+
+int foo (int i)
+{
+  int a[16];
+  __builtin_memset (a, 42, sizeof (a));
+  return a[i];
+}
+
+/* { dg-final { scan-tree-dump "return 707406378;" "fre1" { target { int32plus } } } } */

gcc/tree-ssa-sccvn.c

@@ -1962,7 +1962,6 @@ vn_reference_lookup_3 (ao_ref *ref, tree vuse, void *vr_,
 	  || ((TREE_CODE (gimple_call_arg (def_stmt, 1)) == INTEGER_CST
 	       || (INTEGRAL_TYPE_P (vr->type) && known_eq (ref->size, 8)))
 	      && CHAR_BIT == 8 && BITS_PER_UNIT == 8
-	      && known_eq (ref->size, maxsize)
 	      && offset.is_constant (&offseti)
 	      && offseti % BITS_PER_UNIT == 0))
       && poly_int_tree_p (gimple_call_arg (def_stmt, 2))