Revert PR16467 change

This reverts the pr16467 change, which was incorrect due to faulty
analysis of the pr16467 testcase.  The failure was not due to a
mismatch in symbol type (ifunc/non-ifunc) but due to a symbol loop
being set up.

See https://sourceware.org/ml/binutils/2016-06/msg00013.html for some
rambling on versioned symbols and ELF shared library symbol overriding
that explain this patch.

bfd/
	PR ld/20159
	PR ld/16467
	* elflink.c (_bfd_elf_merge_symbol): Revert PR16467 change.
	(_bfd_elf_add_default_symbol): Don't indirect to/from defined
	symbol given a version by a script different to the version
	of the symbol being added.
	(elf_link_add_object_symbols): Use _bfd_elf_strtab_save and
	_bfd_elf_strtab_restore.  Don't fudge dynstr references.
	* elf-strtab.c (_bfd_elf_strtab_restore_size): Delete.
	(struct strtab_save): New.
	(_bfd_elf_strtab_save, _bfd_elf_strtab_restore): New functions.
	* elf-bfd.h (_bfd_elf_strtab_restore_size): Delete.
	(_bfd_elf_strtab_save, _bfd_elf_strtab_restore): Declare.

bfd/ChangeLog

@@ -1,3 +1,19 @@
+2016-05-31  Alan Modra  <amodra@gmail.com>
+
+	PR ld/20159
+	PR ld/16467
+	* elflink.c (_bfd_elf_merge_symbol): Revert PR16467 change.
+	(_bfd_elf_add_default_symbol): Don't indirect to/from defined
+	symbol given a version by a script different to the version
+	of the symbol being added.
+	(elf_link_add_object_symbols): Use _bfd_elf_strtab_save and
+	_bfd_elf_strtab_restore.  Don't fudge dynstr references.
+	* elf-strtab.c (_bfd_elf_strtab_restore_size): Delete.
+	(struct strtab_save): New.
+	(_bfd_elf_strtab_save, _bfd_elf_strtab_restore): New functions.
+	* elf-bfd.h (_bfd_elf_strtab_restore_size): Delete.
+	(_bfd_elf_strtab_save, _bfd_elf_strtab_restore): Declare.
+
 2016-06-01  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>
 
 	* elf32-hppa.h: Add extern "C".

bfd/elf-bfd.h

@@ -2058,9 +2058,11 @@ extern void _bfd_elf_strtab_delref
 extern unsigned int _bfd_elf_strtab_refcount
   (struct elf_strtab_hash *, bfd_size_type);
 extern void _bfd_elf_strtab_clear_all_refs
-  (struct elf_strtab_hash *tab);
+  (struct elf_strtab_hash *);
-extern void _bfd_elf_strtab_restore_size
+extern void *_bfd_elf_strtab_save
-  (struct elf_strtab_hash *, bfd_size_type);
+  (struct elf_strtab_hash *);
+extern void _bfd_elf_strtab_restore
+  (struct elf_strtab_hash *, void *);
 extern bfd_size_type _bfd_elf_strtab_size
   (struct elf_strtab_hash *);
 extern bfd_size_type _bfd_elf_strtab_offset

bfd/elf-strtab.c

@@ -215,16 +215,45 @@ _bfd_elf_strtab_clear_all_refs (struct elf_strtab_hash *tab)
     tab->array[idx]->refcount = 0;
 }
 
-/* Downsizes strtab.  Entries from IDX up to the current size are
+/* Save strtab refcounts prior to adding --as-needed library.  */
-   removed from the array.  */
+
-void
+struct strtab_save
-_bfd_elf_strtab_restore_size (struct elf_strtab_hash *tab, bfd_size_type idx)
 {
-  bfd_size_type curr_size = tab->size;
+  bfd_size_type size;
+  unsigned int refcount[1];
+};
+
+void *
+_bfd_elf_strtab_save (struct elf_strtab_hash *tab)
+{
+  struct strtab_save *save;
+  bfd_size_type idx, size;
+
+  size = sizeof (*save) + (tab->size - 1) * sizeof (save->refcount[0]);
+  save = bfd_malloc (size);
+  if (save == NULL)
+    return save;
+
+  save->size = tab->size;
+  for (idx = 1; idx < tab->size; idx++)
+    save->refcount[idx] = tab->array[idx]->refcount;
+  return save;
+}
+
+/* Restore strtab refcounts on finding --as-needed library not needed.  */
+
+void
+_bfd_elf_strtab_restore (struct elf_strtab_hash *tab, void *buf)
+{
+  bfd_size_type idx, curr_size = tab->size;
+  struct strtab_save *save = (struct strtab_save *) buf;
 
   BFD_ASSERT (tab->sec_size == 0);
-  BFD_ASSERT (idx <= curr_size);
+  BFD_ASSERT (save->size <= curr_size);
-  tab->size = idx;
+  tab->size = save->size;
+  for (idx = 1; idx < save->size; ++idx)
+    tab->array[idx]->refcount = save->refcount[idx];
+
   for (; idx < curr_size; ++idx)
     {
       /* We don't remove entries from the hash table, just set their

bfd/elflink.c

@@ -1202,21 +1202,20 @@ _bfd_elf_merge_symbol (bfd *abfd,
   oldfunc = (h->type != STT_NOTYPE
 	     && bed->is_function_type (h->type));
 
-  /* When we try to create a default indirect symbol from the dynamic
+  /* If creating a default indirect symbol ("foo" or "foo@") from a
-     definition with the default version, we skip it if its type and
+     dynamic versioned definition ("foo@@") skip doing so if there is
-     the type of existing regular definition mismatch.  */
+     an existing regular definition with a different type.  We don't
+     want, for example, a "time" variable in the executable overriding
+     a "time" function in a shared library.  */
   if (pold_alignment == NULL
       && newdyn
       && newdef
       && !olddyn
-      && (((olddef || h->root.type == bfd_link_hash_common)
+      && (olddef || h->root.type == bfd_link_hash_common)
       && ELF_ST_TYPE (sym->st_info) != h->type
       && ELF_ST_TYPE (sym->st_info) != STT_NOTYPE
       && h->type != STT_NOTYPE
       && !(newfunc && oldfunc))
-	  || (olddef
-	      && ((h->type == STT_GNU_IFUNC)
-		  != (ELF_ST_TYPE (sym->st_info) == STT_GNU_IFUNC)))))
     {
       *skip = TRUE;
       return TRUE;
@@ -1781,6 +1780,31 @@ _bfd_elf_add_default_symbol (bfd *abfd,
   if (skip)
     goto nondefault;
 
+  if (hi->def_regular)
+    {
+      /* If the undecorated symbol will have a version added by a
+	 script different to H, then don't indirect to/from the
+	 undecorated symbol.  This isn't ideal because we may not yet
+	 have seen symbol versions, if given by a script on the
+	 command line rather than via --version-script.  */
+      if (hi->verinfo.vertree == NULL && info->version_info != NULL)
+	{
+	  bfd_boolean hide;
+
+	  hi->verinfo.vertree
+	    = bfd_find_version_for_sym (info->version_info,
+					hi->root.root.string, &hide);
+	  if (hi->verinfo.vertree != NULL && hide)
+	    {
+	      (*bed->elf_backend_hide_symbol) (info, hi, TRUE);
+	      goto nondefault;
+	    }
+	}
+      if (hi->verinfo.vertree != NULL
+	  && strcmp (p + 1 + (p[1] == '@'), hi->verinfo.vertree->name) != 0)
+	goto nondefault;
+    }
+
   if (! override)
     {
       /* Add the default symbol if not performing a relocatable link.  */
@@ -3591,8 +3615,7 @@ elf_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info)
   void *old_ent;
   struct bfd_link_hash_entry *old_undefs = NULL;
   struct bfd_link_hash_entry *old_undefs_tail = NULL;
-  long old_dynsymcount = 0;
+  void *old_strtab = NULL;
-  bfd_size_type old_dynstr_size = 0;
   size_t tabsize = 0;
   asection *s;
   bfd_boolean just_syms;
@@ -4036,8 +4059,9 @@ error_free_dyn:
       old_table = htab->root.table.table;
       old_size = htab->root.table.size;
       old_count = htab->root.table.count;
-      old_dynsymcount = htab->dynsymcount;
+      old_strtab = _bfd_elf_strtab_save (htab->dynstr);
-      old_dynstr_size = _bfd_elf_strtab_size (htab->dynstr);
+      if (old_strtab == NULL)
+	goto error_free_vers;
 
       for (i = 0; i < htab->root.table.size; i++)
 	{
@@ -4762,7 +4786,9 @@ error_free_dyn:
       memcpy (htab->root.table.table, old_tab, tabsize);
       htab->root.undefs = old_undefs;
       htab->root.undefs_tail = old_undefs_tail;
-      _bfd_elf_strtab_restore_size (htab->dynstr, old_dynstr_size);
+      _bfd_elf_strtab_restore (htab->dynstr, old_strtab);
+      free (old_strtab);
+      old_strtab = NULL;
       for (i = 0; i < htab->root.table.size; i++)
 	{
 	  struct bfd_hash_entry *p;
@@ -4775,9 +4801,6 @@ error_free_dyn:
 	      h = (struct elf_link_hash_entry *) p;
 	      if (h->root.type == bfd_link_hash_warning)
 		h = (struct elf_link_hash_entry *) h->root.u.i.link;
-	      if (h->dynindx >= old_dynsymcount
-		  && h->dynstr_index < old_dynstr_size)
-		_bfd_elf_strtab_delref (htab->dynstr, h->dynstr_index);
 
 	      /* Preserve the maximum alignment and size for common
 		 symbols even if this dynamic lib isn't on DT_NEEDED
@@ -5099,6 +5122,8 @@ error_free_dyn:
  error_free_vers:
   if (old_tab != NULL)
     free (old_tab);
+  if (old_strtab != NULL)
+    free (old_strtab);
   if (nondeflt_vers != NULL)
     free (nondeflt_vers);
   if (extversym != NULL)