[committed] testsuite: Add testcase for already fixed PR [PR94573]

[Jakub Jelinek]

Hi!

The following testcase is optimized since Eric's r10-3575 change.

Tested on x86_64-linux -m32/-m64 (and in 9 where it FAILs), committed to
trunk as obvious.

2020-04-14  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94573
	* gcc.dg/store_merging_30.c: New test.

--- gcc/testsuite/gcc.dg/store_merging_30.c.jj	2020-04-14 15:51:59.749645994 +0200
+++ gcc/testsuite/gcc.dg/store_merging_30.c	2020-04-14 15:53:57.222908241 +0200
@@ -0,0 +1,20 @@
+/* PR tree-optimization/94573 */
+/* { dg-do compile } */
+/* { dg-require-effective-target store_merge } */
+/* { dg-options "-O2 -fdump-tree-store-merging-details" } */
+/* { dg-final { scan-tree-dump "New sequence of 4 stores to replace old one of 8 stores" "store-merging" { target lp64 } } } */
+
+int var[43][12];
+
+void
+foo (int x)
+{
+  var[x][0] = 0;
+  var[x][1] = 0;
+  var[x][2] = 0;
+  var[x][3] = 0;
+  var[x][4] = 0;
+  var[x][5] = 0;
+  var[x][6] = 0;
+  var[x][7] = 0;
+}

	Jakub