[PATCH testsuite]XFAIL gcc.dg/tree-ssa/pr71347 on some targets

[Bin Cheng]

Hi,
Test gcc.dg/tree-ssa/pr71347 failed on some targets if the two memory 
references are re-written into different forms by IVOPT.  This could be because 
of various reasons, for example, auto-increment addressing mode.  Since the 
address expressions are of different form, DOM fails to eliminate the redundant 
load at the moment.  I think DOM should be improved to handle address 
expressions appearing in different forms (at least for simple cases).  For now, 
I will XFAIL this test indicating a possible enhancement.

Test checked on affected targets.  Is it OK?

Thanks,
bin

gcc/testsuite/ChangeLog
2016-06-20  Bin Cheng  <bin.ch...@arm.com>

        PR tree-optimization/71347
        * gcc.dg/tree-ssa/pr71347.c: XFAIL on ia64, arm, m68k and sparc.

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr71347.c 
b/gcc/testsuite/gcc.dg/tree-ssa/pr71347.c
index c8f87a9..428e41b 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr71347.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr71347.c
@@ -14,4 +14,4 @@ void foo (void)
 }
 
 /* Load of X[i - i] can be omitted by reusing X[i] in previous iteration.  */
-/* { dg-final { scan-tree-dump-not ".* = MEM.*;" "optimized"} } */
+/* { dg-final { scan-tree-dump-not ".* = MEM.*;" "optimized" { xfail { 
ia64-*-* arm*-*-* m68k*-*-* sparc*-*-* } } } } */