From patchwork Mon Jul  5 23:50:36 2010
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Subject: Fix undefined symbols in WHOPR build of Mozilla's javascript
 interpretter
Date: Mon, 05 Jul 2010 13:50:36 -0000
From: Jan Hubicka <hubicka@ucw.cz>
X-Patchwork-Id: 57945
Message-Id: <20100705235036.GC12132@kam.mff.cuni.cz>
To: gcc-patches@gcc.gnu.org, martinj@suse.cz, rguenther@suse.de

Hi,
this patch solves problem with building Mozilla javascript shell with
-fwhole-program and WHOPR.  The problem here is that cloning causes
devirtualization.  This devirtualization is recognized during virtual clone
materialization (i.e. late) because Martin did not merge his IPA
devritualization code yet.

Because WHOPR brings the function static and house it in different file
than the devirtualized call, we get undefined symbol on the partition.

This problem is not limited to WHOPR only. Same problem can appear in
normal compilation when call to COMDAT function is devirtualized after
COMDAT was declared dead.

This patch adds neccesary checking and prevents devirtualization when we
can't anymore.

Bootstrapped/regtested x86_64-linux, OK?

Honza

	* gimple-fold.c (gimple_fold_obj_type_ref_known_binfo): Check that
	function is still available to fold into.


Index: gimple-fold.c
===================================================================
--- gimple-fold.c	(revision 161847)
+++ gimple-fold.c	(working copy)
@@ -1351,6 +1351,7 @@ gimple_fold_obj_type_ref_known_binfo (HO
 {
   HOST_WIDE_INT i;
   tree v, fndecl;
+  struct cgraph_node *node;
 
   v = BINFO_VIRTUALS (known_binfo);
   i = 0;
@@ -1362,6 +1363,14 @@ gimple_fold_obj_type_ref_known_binfo (HO
     }
 
   fndecl = TREE_VALUE (v);
+  node = cgraph_get_node (fndecl);
+  /* When cgraph node is missing and function is public, we can not
+     devirtualize.  This can happen in WHOPR when the actual method
+     ends up in other partition, because we found devirtualization
+     possibility too late.  */
+  if ((!node || !node->analyzed)
+      && (!TREE_PUBLIC (fndecl) || DECL_COMDAT (fndecl)))
+    return NULL;
   return build_fold_addr_expr (fndecl);
 }