builtin-return-1.c: Add an inline assembly read to make sure dummy is not optimized away by LTO.

2015-12-08  Andre Vieira  <andre.simoesdiasvieira@arm.com>
            Joern Rennecke  <joern.rennecke@embecosm.com>

    gcc/testsuite/
    * gcc.dg/torture/stackalign/builtin-return-1.c: Add an
    inline assembly read to make sure dummy is not optimized
    away by LTO.

Co-Authored-By: Joern Rennecke <joern.rennecke@embecosm.com>

From-SVN: r231401

gcc/testsuite/ChangeLog

+2015-12-08  Andre Vieira  <andre.simoesdiasvieira@arm.com>
+	    Joern Rennecke  <joern.rennecke@embecosm.com>
+
+	* gcc.dg/torture/stackalign/builtin-return-1.c: Add an
+	inline assembly read to make sure dummy is not optimized
+	away by LTO.
+
 2015-12-08  Ilya Enkovich  <enkovich.gnu@gmail.com>
 
 	PR tree-optimization/68766

gcc/testsuite/gcc.dg/torture/stackalign/builtin-return-1.c

@@ -26,15 +26,13 @@ int bar(int n)
 				   STACK_ARGUMENTS_SIZE));
 }
 
-char *g;
-
 int main(void)
 {
   /* Allocate 64 bytes on the stack to make sure that __builtin_apply
      can read at least 64 bytes above the return address.  */
   char dummy[64];
 
-  g = dummy;
+  __asm__ ("" : : "" (dummy));
 
   if (bar(1) != 2)
     abort();