re PR middle-end/78684 (ICE in create_intersect_range_checks_index, at tree-vect-loop-manip.c:2074)

	PR middle-end/78684
	* tree-vect-loop-manip.c (create_intersect_range_checks_index): Check
	sign bit for index step of data reference.
	gcc/testsuite
	PR middle-end/78684
	* g++.dg/torture/pr78684.C: New test.

From-SVN: r243431

gcc/ChangeLog

+2016-12-08  Bin Cheng  <bin.cheng@arm.com>
+
+	PR middle-end/78684
+	* tree-vect-loop-manip.c (create_intersect_range_checks_index): Check
+	sign bit for index step of data reference.
+
 2016-12-08  Naveen H.S  <Naveen.Hurugalawadi@cavium.com>
 
 	* config/aarch64/aarch64.c (aarch64_load_symref_appropriately):

gcc/testsuite/ChangeLog

+2016-12-08  Bin Cheng  <bin.cheng@arm.com>
+
+	PR middle-end/78684
+	* g++.dg/torture/pr78684.C: New test.
+
 2016-12-08  Christophe Lyon  <christophe.lyon@linaro.org>
 
 	* gcc.target/aarch64/advsimd-intrinsics/arm-neon-ref.h

gcc/testsuite/g++.dg/torture/pr78684.C

+// PR middle-end/78684
+// { dg-do compile }
+
+class a {
+public:
+  a(long);
+  void operator<<=(long) {
+    long b;
+    for (unsigned long c; c; c--)
+      d[c + b] = d[c];
+  }
+  a &g();
+  long d[28];
+};
+long e;
+int f;
+void j() {
+  a h(e), i = h;
+  i.g() <<= f;
+}

gcc/tree-vect-loop-manip.c

@@ -2070,8 +2070,7 @@ create_intersect_range_checks_index (loop_vec_info loop_vinfo, tree *cond_expr,
       /* Index must have const step, otherwise DR_STEP won't be constant.  */
       gcc_assert (TREE_CODE (idx_step) == INTEGER_CST);
       /* Index must evaluate in the same direction as DR.  */
-      gcc_assert (!neg_step
-		  || tree_int_cst_compare (idx_step, size_zero_node) < 0);
+      gcc_assert (!neg_step || tree_int_cst_sign_bit (idx_step) == 1);
 
       tree min1 = CHREC_LEFT (access1);
       tree min2 = CHREC_LEFT (access2);