re PR tree-optimization/20489 (ICE: address taken, but ADDRESSABLE bit not set)

2005-03-16  Daniel Berlin  <dberlin@dberlin.org>

	Fix PR tree-optimization/20489

	* tree-ssa-alias.c (push_fields_onto_fieldstack): DTRT
	for empty structures.

From-SVN: r96562

gcc/ChangeLog

 2005-03-16  Daniel Berlin  <dberlin@dberlin.org>
+	
+	Fix PR tree-optimization/20489
+
+	* tree-ssa-alias.c (push_fields_onto_fieldstack): DTRT
+	for empty structures.
+
+2005-03-16  Daniel Berlin  <dberlin@dberlin.org>
 
 	Fix PR tree-optimization/20490
 	

gcc/testsuite/g++.dg/tree-ssa/pr20489.C

+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+struct A
+{
+	~A();
+};
+
+/* If we don't create SFT's for the "empty" structure A, bad things
+   will happen, and we will fail verification.  */
+struct B
+{
+	int i;
+	A a;
+
+	void foo() {}
+};
+
+void bar()
+{
+	B().foo();
+}

gcc/tree-ssa-alias.c

@@ -2729,8 +2729,21 @@ push_fields_onto_fieldstack (tree type, VEC(fieldoff_t) **fieldstack,
 	continue;
       if (var_can_have_subvars (field))
 	{
+	  size_t before = VEC_length (fieldoff_t, *fieldstack);
 	  push_fields_onto_fieldstack (TREE_TYPE (field), fieldstack, 
 				       offset + bitpos_of_field (field));
+      /* Empty structures may have actual size, like in C++. So see if we
+	 actually end up pushing a field, and if not, if the size is non-zero,
+	 push the field onto the stack */
+	  if (before == VEC_length (fieldoff_t, *fieldstack)
+	      && DECL_SIZE (field)
+	      && !integer_zerop (DECL_SIZE (field)))
+	    {
+	      pair = xmalloc (sizeof (struct fieldoff));
+	      pair->field = field;
+	      pair->offset = offset + bitpos_of_field (field);
+	      VEC_safe_push (fieldoff_t, *fieldstack, pair);
+	    }
 	}
       else
 	{