Do not bail out for multiple PREVAILING_DEF_IRONLY for common symbols.

2018-04-19  Martin Liska  <mliska@suse.cz>

	* lto-symtab.c (lto_symtab_resolve_symbols): Do not bail out
	for multiple PREVAILING_DEF_IRONLY for common symbols.

From-SVN: r259490

gcc/lto/ChangeLog

+2018-04-19  Martin Liska  <mliska@suse.cz>
+
+	* lto-symtab.c (lto_symtab_resolve_symbols): Do not bail out
+	for multiple PREVAILING_DEF_IRONLY for common symbols.
+
 2018-04-18  Martin Liska  <mliska@suse.cz>
 
 	* lto.c (lto_read_decls): Fix GNU coding style and typos.

gcc/lto/lto-symtab.c

@@ -466,9 +466,14 @@ lto_symtab_resolve_symbols (symtab_node *first)
   /* If the chain is already resolved there is nothing else to do.  */
   if (prevailing)
     {
-      /* Assert it's the only one.  */
+      /* Assert it's the only one.
+	 GCC should silence multiple PREVAILING_DEF_IRONLY defs error
+	 on COMMON symbols since it isn't error.
+	 See: https://sourceware.org/bugzilla/show_bug.cgi?id=23079.  */
       for (e = prevailing->next_sharing_asm_name; e; e = e->next_sharing_asm_name)
 	if (lto_symtab_symbol_p (e)
+	    && !DECL_COMMON (prevailing->decl)
+	    && !DECL_COMMON (e->decl)
 	    && (e->resolution == LDPR_PREVAILING_DEF_IRONLY
 		|| e->resolution == LDPR_PREVAILING_DEF_IRONLY_EXP
 		|| e->resolution == LDPR_PREVAILING_DEF))