[AArch64] PR tree-optimization/64946: XFAIL gcc.target/aarch64/vect-abs-compile.c

This test has been failing since forever, it has never passed AFAIK.
The PR details the vectoriser deficiency.
I propose we xfail this with a reference to the PR.

        PR tree-optimization/64946
        * gcc.target/aarch64/vect-abs-compile.c: XFAIL byte and half-word
        scan-assembler checks.

From-SVN: r257225

gcc/testsuite/ChangeLog

+2018-01-31  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+	PR tree-optimization/64946
+	* gcc.target/aarch64/vect-abs-compile.c: XFAIL byte and half-word
+	scan-assembler checks.
+
 2018-01-31  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc.c-torture/execute/20180131-1.c: New test.

gcc/testsuite/gcc.target/aarch64/vect-abs-compile.c

@@ -6,7 +6,8 @@
 
 #include "vect-abs.x"
 
-/* { dg-final { scan-assembler "abs\\tv\[0-9\]+\.16b" } } */
-/* { dg-final { scan-assembler "abs\\tv\[0-9\]+\.8h" } } */
+/* XFAIL due to PR tree-optimization/64946.  */
+/* { dg-final { scan-assembler "abs\\tv\[0-9\]+\.16b" { xfail *-*-* } } } */
+/* { dg-final { scan-assembler "abs\\tv\[0-9\]+\.8h" { xfail *-*-* } } } */
 /* { dg-final { scan-assembler "abs\\tv\[0-9\]+\.4s" } } */
 /* { dg-final { scan-assembler "abs\\tv\[0-9\]+\.2d" } } */