[Bug lto/57084] 483. xalancbmk run fails with -O2 -flto for i686

["jamborm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57084

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hubicka at gcc dot gnu.org

--- Comment #2 from Martin Jambor <jamborm at gcc dot gnu.org> 2013-05-02 15:46:35 UTC ---
OK, after I verified and re-verified that the call target determined
by devirtualization is actually correct, I have noticed that the call
graph of the target is an inlined node.  I'm not sure what effects
exactly that has but the following (untested) patch helps while still
performing the devirtualization (and the assembly around the calls is
slightly different).

I think that the final patch will look a bit different because a) the
new code is basically copied from ipa_make_edge_direct_to_target an
thus we'd better commonize it somehow (and I'd like to discuss with
Honza at least the name of the new function) and b) I see no reason
why the constructor-based devirtualization method in PRE cannot have
the same problem and so we'll probably want to handle it there instead
(Honza said on IRC something about a patch he already had but I am not
sure what he meant).

Another interesting point is that at least in the 64 bit non-LTO
build, these polymorphic calls are devirtualized during inlining.  I'm
going to look at why we do not do it in 32 bit LTO one (so far I do
not know which one is the problem).


Index: src/gcc/ipa-prop.c
===================================================================
--- src.orig/gcc/ipa-prop.c
+++ src/gcc/ipa-prop.c
@@ -1978,6 +1978,7 @@ ipa_analyze_node (struct cgraph_node *no
 tree
 ipa_intraprocedural_devirtualization (gimple call)
 {
+  struct cgraph_node *callee;
   tree binfo, token, fndecl;
   struct ipa_jump_func jfunc;
   tree otr = gimple_call_fn (call);
@@ -1993,6 +1994,18 @@ ipa_intraprocedural_devirtualization (gi
   token = OBJ_TYPE_REF_TOKEN (otr);
   fndecl = gimple_get_virt_method_for_binfo (tree_low_cst (token, 1),
                          binfo);
+  if (!fndecl)
+    return NULL_TREE;
+
+  callee = cgraph_get_node (fndecl);
+  if (!callee || callee->global.inlined_to)
+    {
+      if (!canonicalize_constructor_val (fndecl, NULL)
+      || !TREE_PUBLIC (fndecl))
+    return NULL_TREE;
+      cgraph_get_create_real_symbol_node (fndecl);
+    }
+
   return fndecl;
 }