Fix pr13201, --as-needed with -flto

[Alan Modra <amodra at gmail dot com>]

This fixes a problem with -flto and --as-needed libraries.  LTO IR
symbols may not contain any references to symbols in an --as-needed
shared lib, causing the library to be omitted even when the LTO
translated output does contain references.  (I believe it is correct
that LTO IR does *not* contain such references.)

	PR ld/12301
	* ldlang.h (lang_input_statement_type): Add "reload" bitfield.
	Clarify comments.
	* ldlang.c (new_afile): Init new field.
	(load_symbols): Don't call ldlang_add_file when reloading.
	(open_input_bfds): Reload as-needed libs during plugin rescan.

Index: ld/ldlang.h
===================================================================
RCS file: /cvs/src/src/ld/ldlang.h,v
retrieving revision 1.99
diff -u -p -r1.99 ldlang.h
--- ld/ldlang.h	16 Sep 2011 01:15:19 -0000	1.99
+++ ld/ldlang.h	20 Sep 2011 02:29:14 -0000
@@ -270,12 +270,13 @@ typedef struct lang_input_statement_stru
   /* Whether to search for this entry as a dynamic archive.  */
   unsigned int dynamic : 1;
 
-  /* Whether DT_NEEDED tags should be added for dynamic libraries in
-     DT_NEEDED tags from this entry.  */
+  /* Set if a DT_NEEDED tag should be added not just for the dynamic library
+     explicitly given by this entry but also for any dynamic libraries in
+     this entry's needed list.  */
   unsigned int add_DT_NEEDED_for_dynamic : 1;
 
-  /* Whether this entry should cause a DT_NEEDED tag only when
-     satisfying references from regular files, or always.  */
+  /* Set if this entry should cause a DT_NEEDED tag only when some
+     regular file references its symbols (ie. --as-needed is in effect).  */
   unsigned int add_DT_NEEDED_for_regular : 1;
 
   /* Whether to include the entire contents of an archive.  */
@@ -295,6 +296,9 @@ typedef struct lang_input_statement_stru
 
   /* Set if the file was claimed from an archive.  */
   unsigned int claim_archive : 1;
+
+  /* Set if reloading an --as-needed lib.  */
+  unsigned int reload : 1;
 #endif /* ENABLE_PLUGINS */
 
 } lang_input_statement_type;
Index: ld/ldlang.c
===================================================================
RCS file: /cvs/src/src/ld/ldlang.c,v
retrieving revision 1.377
diff -u -p -r1.377 ldlang.c
--- ld/ldlang.c	16 Sep 2011 01:15:19 -0000	1.377
+++ ld/ldlang.c	20 Sep 2011 02:29:14 -0000
@@ -1133,6 +1133,7 @@ new_afile (const char *name,
 #ifdef ENABLE_PLUGINS
   p->claimed = FALSE;
   p->claim_archive = FALSE;
+  p->reload = FALSE;
 #endif /* ENABLE_PLUGINS */
 
   lang_statement_append (&input_file_chain,
@@ -2780,7 +2781,10 @@ load_symbols (lang_input_statement_type 
       break;
 
     case bfd_object:
-      ldlang_add_file (entry);
+#ifdef ENABLE_PLUGINS
+      if (!entry->reload)
+#endif
+	ldlang_add_file (entry);
       if (trace_files || trace_file_tries)
 	info_msg ("%I\n", entry);
       break;
@@ -3272,6 +3276,18 @@ open_input_bfds (lang_statement_union_ty
 		  && bfd_check_format (s->input_statement.the_bfd,
 				       bfd_archive))
 		s->input_statement.loaded = FALSE;
+#ifdef ENABLE_PLUGINS
+	      /* When rescanning, reload --as-needed shared libs.  */
+	      else if ((mode & OPEN_BFD_RESCAN) != 0
+		       && plugin_insert == NULL
+		       && s->input_statement.loaded
+		       && s->input_statement.add_DT_NEEDED_for_regular
+		       && ((s->input_statement.the_bfd->flags) & DYNAMIC) != 0)
+		{
+		  s->input_statement.loaded = FALSE;
+		  s->input_statement.reload = TRUE;
+		}
+#endif
 
 	      os_tail = lang_output_section_statement.tail;
 	      lang_list_init (&add);

-- 
Alan Modra
Australia Development Lab, IBM