http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56557
--- Comment #9 from Jan Hubicka <hubicka at gcc dot gnu.org> 2013-03-11 18:10:57 UTC --- I am testing the following that should prevent references from external vtables to land in LTO symbol table. Index: lto-streamer-out.c =================================================================== --- lto-streamer-out.c (revision 196596) +++ lto-streamer-out.c (working copy) @@ -1265,17 +1265,36 @@ bool output_symbol_p (symtab_node node) { struct cgraph_node *cnode; - struct ipa_ref *ref; - if (!symtab_real_symbol_p (node)) return false; /* We keep external functions in symtab for sake of inlining and devirtualization. We do not want to see them in symbol table as - references. */ + references unless they are really used. */ cnode = dyn_cast <cgraph_node> (node); - if (cnode && DECL_EXTERNAL (cnode->symbol.decl)) - return (cnode->callers - || ipa_ref_list_referring_iterate (&cnode->symbol.ref_list, 0, ref)); + if (cnode && DECL_EXTERNAL (cnode->symbol.decl) + && cnode->callers) + return true; + + /* Ignore all referrences from external vars initializers - they are not really + part of the compilation unit until they are used by folding. Some symbols, + like referneces to external construction vtables can not be referred to at all. + We decide this at can_refer_decl_in_current_unit_p */ + if (DECL_EXTERNAL (node->symbol.decl)) + { + int i; + struct ipa_ref *ref; + for (i = 0; ipa_ref_list_referring_iterate (&node->symbol.ref_list, + i, ref); i++) + { + if (ref->use == IPA_REF_ALIAS) + continue; + if (is_a <cgraph_node> (ref->referring)) + return true; + if (!DECL_EXTERNAL (ref->referring->symbol.decl)) + return true; + } + return false; + } return true; }