[backport gcc-4.9/trunk r199240 <mikpe@it.uu.se>]

gcc/

2013-05-23  Richard Biener  <rguenther@suse.de>

	PR middle-end/57381
	* fold-const.c (operand_equal_p): Compare FIELD_DECLs with
	OEP_CONSTANT_ADDRESS_OF retained.

gcc/testsuite/

2013-05-23  Richard Biener  <rguenther@suse.de>

	PR middle-end/57381
	* gcc.dg/torture/pr57381.c: New testcase.

--- gcc-4.8.0/gcc/fold-const.c.~1~	2013-02-26 11:00:31.000000000 +0100
+++ gcc-4.8.0/gcc/fold-const.c	2013-05-25 12:13:16.855220798 +0200
@@ -2600,10 +2600,10 @@ operand_equal_p (const_tree arg0, const_
 	case COMPONENT_REF:
 	  /* Handle operand 2 the same as for ARRAY_REF.  Operand 0
 	     may be NULL when we're called to compare MEM_EXPRs.  */
-	  if (!OP_SAME_WITH_NULL (0))
+	  if (!OP_SAME_WITH_NULL (0) || !OP_SAME (1))
 	    return 0;
 	  flags &= ~OEP_CONSTANT_ADDRESS_OF;
-	  return OP_SAME (1) && OP_SAME_WITH_NULL (2);
+	  return OP_SAME_WITH_NULL (2);
 
 	case BIT_FIELD_REF:
 	  if (!OP_SAME (0))
--- gcc-4.8.0/gcc/testsuite/gcc.dg/torture/pr57381.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.8.0/gcc/testsuite/gcc.dg/torture/pr57381.c	2013-05-25 12:13:16.855220798 +0200
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+
+struct S0 { int  f0, f1, f2; };
+
+struct S1 {
+    int  f0;
+    volatile struct S0 f2;
+};
+
+static struct S1 s = {0x47BED265,{0x06D4EB3E,5,0U}};
+
+int foo(struct S0 p)
+{
+  for (s.f2.f2 = 0; (s.f2.f2 <= 12); s.f2.f2++)
+    {
+      volatile int *l_61[5][2][2] = {{{&s.f2.f0,&s.f2.f0},{&s.f2.f0,&s.f2.f0}},{{&s.f2.f0,&s.f2.f0},{&s.f2.f0,&s.f2.f0}},{{&s.f2.f0,(void*)0},{&s.f2.f0,&s.f2.f0}},{{&s.f2.f0,&s.f2.f0},{&s.f2.f0,&s.f2.f0}},{{&s.f2.f0,&s.f2.f0},{(void*)0,&s.f2.f0}}};
+
+      volatile int **l_68 = &l_61[0][0][1];
+      volatile int *l_76 = &s.f2.f0;
+      (*l_68) = l_61[0][0][0];
+      if ((*l_76 = (p.f2 % 5))) ;
+    }
+  return p.f0;
+}