Fix store merging tests on Arm

Fix the failing store merging test on Arm.  Aligning variables fixes a
few cases, otherwise disable the test on Arm.  All store merging tests
now pass.  Committed as obvious.

    testsuite/
	* gcc.dg/store_merging_27.c: Fix test for Arm.
	* gcc.dg/store_merging_28.c: Likewise.
	* gcc.dg/store_merging_29.c: Likewise.
	* gcc.dg/tree-ssa/dump-6.c: Likewise.

From-SVN: r273011

gcc/testsuite/ChangeLog

+2019-07-03  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	* gcc.dg/store_merging_27.c: Fix test for Arm.
+	* gcc.dg/store_merging_28.c: Likewise.
+	* gcc.dg/store_merging_29.c: Likewise.
+	* gcc.dg/tree-ssa/dump-6.c: Likewise.
+
 2019-07-03  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/91069

gcc/testsuite/gcc.dg/store_merging_27.c

@@ -18,7 +18,7 @@ bar (struct S *x)
 int
 main ()
 {
-  struct S s = {};
+  __attribute__((aligned(8))) struct S s = {};
   s.buf[1] = 1;
   s.buf[3] = 2;
   bar (&s);

gcc/testsuite/gcc.dg/store_merging_28.c

@@ -3,7 +3,7 @@
 /* { dg-require-effective-target store_merge } */
 /* { dg-options "-O2 -fno-ipa-icf -fdump-tree-store-merging-details" } */
 /* { dg-final { scan-tree-dump-times "New sequence of \[24] stores to replace old one of 16 stores" 8 "store-merging" { target { i?86-*-* x86_64-*-* } } } } */
-/* { dg-final { scan-tree-dump-times "New sequence of \[24] stores to replace old one of 6 stores" 1 "store-merging" } } */
+/* { dg-final { scan-tree-dump-times "New sequence of \[24] stores to replace old one of 6 stores" 1 "store-merging" { target { ! arm*-*-* } } } } */
 
 typedef struct S { char data[16]; } S;
 void optimize_me (S);

gcc/testsuite/gcc.dg/store_merging_29.c

@@ -3,7 +3,7 @@
 /* { dg-require-effective-target store_merge } */
 /* { dg-options "-O2 -fdump-tree-store-merging-details" } */
 /* { dg-final { scan-tree-dump "New sequence of 3 stores to replace old one of 6 stores" "store-merging" { target { le && { ! arm*-*-* } } } } } */
-/* { dg-final { scan-tree-dump "New sequence of \[34] stores to replace old one of 6 stores" "store-merging" { target { be || { arm*-*-* } } } } } */
+/* { dg-final { scan-tree-dump "New sequence of \[34] stores to replace old one of 6 stores" "store-merging" { target { be && { ! arm*-*-* } } } } } */
 
 struct T { char a[1024]; };
 

gcc/testsuite/gcc.dg/tree-ssa/dump-6.c

@@ -5,7 +5,7 @@
    { dg-require-effective-target store_merge } */
 
 
-extern char a2[2];
+extern __attribute__((aligned(2))) char a2[2];
 
 void f2 (void)
 {
@@ -13,7 +13,7 @@ void f2 (void)
   a2[1] = 0;
 }
 
-extern char a4[4];
+extern __attribute__((aligned(4))) char a4[4];
 
 void f4 (void)
 {
@@ -23,7 +23,7 @@ void f4 (void)
   a4[3] = 0;
 }
 
-extern char a8[8];
+extern __attribute__((aligned(8))) char a8[8];
 
 void f8 (void)
 {