re PR rtl-optimization/47698 (CMOV accessing volatile memory with read side effect)

gcc/
	PR rtl-optimization/47698
	* ifconv.c (noce_operand_ok): prevent CMOV generation
	for volatile mem.

gcc/testsuite/
	PR rtl-optimization/47698
	* gcc.target/i386/47698.c: New test.

From-SVN: r181075

gcc/ChangeLog

+2011-11-07  Sergey Ostanevich  <sergos.gnu@gmail.com>
+
+	PR rtl-optimization/47698
+	* ifconv.c (noce_operand_ok): prevent CMOV generation
+	for volatile mem.
+
 2011-11-07  Tristan Gingold  <gingold@adacore.com>
 
 	* common/config/alpha/alpha-common.c (alpha_option_init_struct):

gcc/ifcvt.c

@@ -2329,12 +2329,12 @@ noce_operand_ok (const_rtx op)
 {
   /* We special-case memories, so handle any of them with
      no address side effects.  */
-  if (MEM_P (op))
-    return ! side_effects_p (XEXP (op, 0));
-
   if (side_effects_p (op))
     return FALSE;
 
+  if (MEM_P (op))
+    return ! side_effects_p (XEXP (op, 0));
+
   return ! may_trap_p (op);
 }
 

gcc/testsuite/ChangeLog

+
+2011-11-07  Sergey Ostanevich  <sergos.gnu@gmail.com>
+
+	PR rtl-optimization/47698
+	* gcc.target/i386/47698.c: New test.
+
 2011-11-06  Jason Merrill  <jason@redhat.com>
 
 	PR c++/35688

gcc/testsuite/gcc.target/i386/47698.c

+/* { dg-options "-Os" } */
+/* { dg-final { scan-assembler-not "cmov" } } */
+
+extern volatile unsigned long mmio;
+unsigned long foo(int cond)
+{
+      if (cond)
+              return mmio;
+        return 0;
+}