[Patch, testsuite] Skip addr_equal-1 if target keeps null pointer checks

[Senthil Kumar Selvaraj <senthil_kumar dot selvaraj at atmel dot com>]

Hi,

  The below patch skips gcc.dg/addr_equal-1.c if the target keeps null
  pointer checks.

  The test fails for such targets (avr, in my case) because the address
  comparison in the below code does not resolve to a constant, causing
  builtin_constant_p to return false and fail the test.

  /* Variables and functions do not share same memory locations otherwise.  */
  if (!__builtin_constant_p ((void *)undef_fn0 == (void *)&undef_var0))
    abort ();

  For targets that delete null pointer checks, the equality comparison expression
  is optimized away to 0, as the code in match.pd knows they can only be
  equal if they are both NULL, which cannot be true since
  flag-delete-null-pointer-checks is on.

  For targets that keep null pointer checks, 0 is a valid address and the 
	comparison expression is left as is, and that causes a later pass to 
	fold the builtin_constant_p to a false value, resulting in the test failure.

  If this is ok, could someone commit please? I don't have commit
  access.

Regards
Senthil

gcc/testsuite/ChangeLog

2015-09-28  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>

	* gcc.dg/addr_equal-1.c: Skip test if target keeps
	null pointer checks.

diff --git gcc/testsuite/gcc.dg/addr_equal-1.c gcc/testsuite/gcc.dg/addr_equal-1.c
index 94499f0..957b03a 100644
--- gcc/testsuite/gcc.dg/addr_equal-1.c
+++ gcc/testsuite/gcc.dg/addr_equal-1.c
@@ -3,6 +3,7 @@
 /* { dg-require-weak "" } */
 /* { dg-require-alias "" } */
 /* { dg-options "-O2" } */
+/* { dg-skip-if "" keeps_null_pointer_checks } */
 void abort (void);
 extern int undef_var0, undef_var1;
 extern __attribute__ ((weak)) int weak_undef_var0;