Add more markup to vect-alias-check-{1,18}.c (PR 92543)

In vect-alias-check-1.c we unroll the inner loop and then vectorise
the stores at a[c + 1][b].  Since the access has no guaranteed
alignemnt, we need a realignment mechanism or support for unaligned
accesses in order to vectorise.

In vect-alias-check-18.c we use a reverse access and so need
permute support in order to vectorise.

I'm not really sure when this part of the testsuite prefers
{ xfail { ! foo } } and when it prefers { target foo }.  xfail
seems like the most common choice for the alignment restriction,
whereas vect_int and vect_perm are mostly dg-require-effective-target
style features, so I went with that combination.

2019-11-21  Richard Sandiford  <richard.sandiford@arm.com>

gcc/testsuite/
	PR testsuite/92543
	* gcc.dg/vect/vect-alias-check-1.c: XFAIL the alias check message
	if there is no realignment support and no support for unaligned
	accesses.
	* gcc.dg/vect/vect-alias-check-18.c: Restrict the test for the
	alias message to targets that have permute support.

From-SVN: r278591

gcc/testsuite/ChangeLog

 2019-11-21  Richard Sandiford  <richard.sandiford@arm.com>
 
+	PR testsuite/92543
+	* gcc.dg/vect/vect-alias-check-1.c: XFAIL the alias check message
+	if there is no realignment support and no support for unaligned
+	accesses.
+	* gcc.dg/vect/vect-alias-check-18.c: Restrict the test for the
+	alias message to targets that have permute support.
+
+2019-11-21  Richard Sandiford  <richard.sandiford@arm.com>
+
 	PR tree-optimization/92595
 	* g++.dg/vect/pr92595.cc: New test.
 

gcc/testsuite/gcc.dg/vect/vect-alias-check-1.c

@@ -15,5 +15,5 @@ fn1 ()
 }
 
 /* { dg-final { scan-tree-dump "improved number of alias checks from \[0-9\]* to 1" "vect" } } */
-/* { dg-final { scan-tree-dump "using an address-based overlap test" "vect" } } */
+/* { dg-final { scan-tree-dump "using an address-based overlap test" "vect" { xfail { vect_no_align && { ! vect_hw_misalign } } } } } */
 /* { dg-final { scan-tree-dump-not "using an index-based" "vect" } } */

gcc/testsuite/gcc.dg/vect/vect-alias-check-18.c

@@ -60,5 +60,5 @@ main (void)
 }
 
 /* { dg-final { scan-tree-dump {flags: *WAR\n} "vect" { target vect_int } } } */
-/* { dg-final { scan-tree-dump "using an index-based WAR/WAW test" "vect" } } */
+/* { dg-final { scan-tree-dump "using an index-based WAR/WAW test" "vect" { target { vect_int && vect_perm } } } } */
 /* { dg-final { scan-tree-dump-not "using an address-based" "vect" } } */