re PR tree-optimization/42386 (ICE in ipcp_iterate_stage, at ipa-cp.c:766)

	PR c++/42386
	* ipa.c (function_and_variable_visibility): Clear same_comdat_group
	links of DECL_EXTERNAL nodes.

	* g++.dg/opt/dtor3.C: New test.

From-SVN: r155321

gcc/ChangeLog

+2009-12-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/42386
+	* ipa.c (function_and_variable_visibility): Clear same_comdat_group
+	links of DECL_EXTERNAL nodes.
+
 2009-12-17  Sandra Loosemore  <sandra@codesourcery.com>
 
 	* doc/rtl.texi (Vector Operations): Clarify vec_select result mode.

gcc/ipa.c

@@ -370,6 +370,23 @@ function_and_variable_visibility (bool whole_program)
 	 happy.  Clear the flag here to avoid confusion in middle-end.  */
       if (DECL_COMDAT (node->decl) && !TREE_PUBLIC (node->decl))
         DECL_COMDAT (node->decl) = 0;
+      /* For external decls stop tracking same_comdat_group, it doesn't matter
+	 what comdat group they are in when they won't be emitted in this TU,
+	 and simplifies later passes.  */
+      if (node->same_comdat_group && DECL_EXTERNAL (node->decl))
+	{
+	  struct cgraph_node *n = node, *next;
+	  do
+	    {
+	      /* If at least one of same comdat group functions is external,
+		 all of them have to be, otherwise it is a front-end bug.  */
+	      gcc_assert (DECL_EXTERNAL (n->decl));
+	      next = n->same_comdat_group;
+	      n->same_comdat_group = NULL;
+	      n = next;
+	    }
+	  while (n != node);
+	}
       gcc_assert ((!DECL_WEAK (node->decl) && !DECL_COMDAT (node->decl))
       	          || TREE_PUBLIC (node->decl) || DECL_EXTERNAL (node->decl));
       if (cgraph_externally_visible_p (node, whole_program))

gcc/testsuite/ChangeLog

+2009-12-17  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/42386
+	* g++.dg/opt/dtor3.C: New test.
+
 2009-12-17  Arnaud Charlet  <charlet@adacore.com>
 
 	* ada/acats/run_all.sh: Strip comments from norun.lst

gcc/testsuite/g++.dg/opt/dtor3.C

+// PR c++/42386
+// { dg-do compile }
+// { dg-options "-O2" }
+# 1 "A.h" 1
+#pragma interface
+struct D { virtual bool d () const; };
+struct E { virtual ~E (); virtual void *e () const = 0; };
+struct A : public D, public E { ~A () {} };
+# 5 "dtor3.C" 1
+struct F : public A { void *f () const; void *e () const; };
+void *F::e () const { return __null; }