Date: Tue, 12 Apr 2005 00:00:15 +0930
From: Alan Modra <amodra at bigpond dot net dot au>
To: binutils at sources dot redhat dot com
Cc: Anton Blanchard <anton at samba dot org>,
	Paul Mackerras <paulus at samba dot org>
Subject: AS_NEEDED failure
Message-ID: <20050411143015.GB861@bubble.modra.org>
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	Anton Blanchard <anton at samba dot org>, Paul Mackerras <paulus at samba dot org>
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On powerpc64, I've hit the following during an X11 server build
.../libdl.so.2: undefined reference to _rtld_global@GLIBC_PRIVATE
This symbol is defined in ld64.so.1, and ld64.so.1 is being searched,
but the following conspires to make the link fail:

- libc.so contains AS_NEEDED (ld64.so.1)
- one or more of the X11 libs has DT_NEEDED libdl.so.2
- libdl.so.2 has DT_NEEDED ld64.so.1

The libc.so AS_NEEDED() causes symbols from ld64.so.1 to be loaded, but
no regular object file needs them so all the ld64.so.1 syms are set back
to bfd_link_hash_new, effectively removing them.  The X11 lib is loaded,
and its DT_NEEDED entry noted.  libdl.so.2 is loaded, but ld decides
that ld64.so.1 has already been looked at, so doesn't load it again.
It should do, because AS_NEEDED lib symbols aren't really loaded.

	* emultempl/elf32.em (gld${EMULATION_NAME}_stat_needed): Ignore
	as_needed libs that were not needed.
	(gld${EMULATION_NAME}_check_needed): Likewise.

Applied mainline.  I think this should go on 2.16, but after some more
testing..

Index: ld/emultempl/elf32.em
===================================================================
RCS file: /cvs/src/src/ld/emultempl/elf32.em,v
retrieving revision 1.138
diff -u -p -r1.138 elf32.em
--- ld/emultempl/elf32.em	4 Apr 2005 11:27:15 -0000	1.138
+++ ld/emultempl/elf32.em	11 Apr 2005 14:23:08 -0000
@@ -230,6 +230,9 @@ gld${EMULATION_NAME}_stat_needed (lang_i
     return;
   if (s->the_bfd == NULL)
     return;
+  if (s->as_needed
+      && (bfd_elf_get_dyn_lib_class (s->the_bfd) & DYN_AS_NEEDED) != 0)
+    return;
 
   if (bfd_stat (s->the_bfd, &st) != 0)
     {
@@ -737,6 +740,13 @@ gld${EMULATION_NAME}_check_needed (lang_
   if (global_found)
     return;
 
+  /* If this input file was an as-needed entry, and wasn't found to be
+     needed at the stage it was linked, then don't say we have loaded it.  */
+  if (s->as_needed
+      && (s->the_bfd == NULL
+	  || (bfd_elf_get_dyn_lib_class (s->the_bfd) & DYN_AS_NEEDED) != 0))
+    return;
+
   if (s->filename != NULL)
     {
       const char *f;

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre