[backport from gcc-4.7.1 r187589, suspected to be latent on 4.6 branch <mikpe@it.uu.se>]

gcc/

2012-05-16  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/53364
	* tree-ssa-alias.c (indirect_ref_may_alias_decl_p): Properly
	detect a view-conversion of the decl.

gcc/testsuite/

2012-05-16  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/53364
	* g++.dg/torture/pr53364.C: New testcase.

--- gcc-4.6.3/gcc/testsuite/g++.dg/torture/pr53364.C.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.6.3/gcc/testsuite/g++.dg/torture/pr53364.C	2012-06-09 22:50:40.000000000 +0200
@@ -0,0 +1,37 @@
+// { dg-do run }
+
+extern "C" void abort (void);
+
+template<typename _Tp>
+inline const _Tp&
+min(const _Tp& __a, const _Tp& __b)
+{
+  if (__b < __a)
+    return __b;
+  return __a;
+}
+
+struct A
+{
+  int m_x;
+
+  explicit A(int x) : m_x(x) {}
+  operator int() const { return m_x; }
+};
+
+struct B : public A
+{
+public:
+  explicit B(int x) : A(x) {}
+};
+
+int data = 1;
+
+int main()
+{
+  B b = B(10);
+  b = min(b, B(data));
+  if (b != 1)
+    abort ();
+  return 0;
+}
--- gcc-4.6.3/gcc/tree-ssa-alias.c.~1~	2011-09-30 20:13:25.000000000 +0200
+++ gcc-4.6.3/gcc/tree-ssa-alias.c	2012-06-09 22:50:40.000000000 +0200
@@ -828,8 +828,7 @@ indirect_ref_may_alias_decl_p (tree ref1
 
   /* If either reference is view-converted, give up now.  */
   if (same_type_for_tbaa (TREE_TYPE (base1), TREE_TYPE (ptrtype1)) != 1
-      || same_type_for_tbaa (TREE_TYPE (dbase2),
-			     TREE_TYPE (reference_alias_ptr_type (dbase2))) != 1)
+      || same_type_for_tbaa (TREE_TYPE (dbase2), TREE_TYPE (base2)) != 1)
     return true;
 
   /* If both references are through the same type, they do not alias