PR24873, gcc -flto objects result in --start-group .. --end-group failure to include --as-needed libraries

[Alan Modra <amodra at gmail dot com>]

Reloading of archives (and checking --as-needed DSOs again) is
disabled until we hit the plugin insert point.  It's necessary to do
that because in a case like lib1.a lto.o lib2.a where lib1.a and
lib2.a contain duplicate symbols, we want the lto.o recompiled object
to pull in objects from lib2.a as necessary, but not from lib1.a.
Unfortunately this heuristic fails when the insert point is inside a
group, because ld actually loads the symbols from the recompiled
object before running over the contours of the script, thus missing
the fact that new undefs appeared in the group.

	PR 24873
	* ldlang.c (plugin_undefs): New static var.
	(open_input_bfds <lang_group_statement_enum>): Loop on
	plugin_undefs and hitting plugin_insert point.
	(lang_process <lto_plugin_active>): Set plugin_undefs.

diff --git a/ld/ldlang.c b/ld/ldlang.c
index 96daf0ef11..b88c841810 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -3444,6 +3444,7 @@ enum open_bfd_mode
   };
 #ifdef ENABLE_PLUGINS
 static lang_input_statement_type *plugin_insert = NULL;
+static struct bfd_link_hash_entry *plugin_undefs = NULL;
 #endif
 
 static void
@@ -3471,6 +3472,9 @@ open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
 	case lang_group_statement_enum:
 	  {
 	    struct bfd_link_hash_entry *undefs;
+#ifdef ENABLE_PLUGINS
+	    lang_input_statement_type *plugin_insert_save;
+#endif
 
 	    /* We must continually search the entries in the group
 	       until no new symbols are added to the list of undefined
@@ -3478,11 +3482,21 @@ open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
 
 	    do
 	      {
+#ifdef ENABLE_PLUGINS
+		plugin_insert_save = plugin_insert;
+#endif
 		undefs = link_info.hash->undefs_tail;
 		open_input_bfds (s->group_statement.children.head,
 				 mode | OPEN_BFD_FORCE);
 	      }
-	    while (undefs != link_info.hash->undefs_tail);
+	    while (undefs != link_info.hash->undefs_tail
+#ifdef ENABLE_PLUGINS
+		   /* Objects inserted by a plugin, which are loaded
+		      before we hit this loop, may have added new
+		      undefs.  */
+		   || (plugin_insert != plugin_insert_save && plugin_undefs)
+#endif
+		   );
 	  }
 	  break;
 	case lang_target_statement_enum:
@@ -7420,7 +7434,10 @@ lang_process (void)
 	einfo (_("%F%P: %s: plugin reported error after all symbols read\n"),
 	       plugin_error_plugin ());
       /* Open any newly added files, updating the file chains.  */
+      plugin_undefs = link_info.hash->undefs_tail;
       open_input_bfds (*added.tail, OPEN_BFD_NORMAL);
+      if (plugin_undefs == link_info.hash->undefs_tail)
+	plugin_undefs = NULL;
       /* Restore the global list pointer now they have all been added.  */
       lang_list_remove_tail (stat_ptr, &added);
       /* And detach the fresh ends of the file lists.  */

-- 
Alan Modra
Australia Development Lab, IBM