* config/obj-elf.c (obj_elf_type): Add code to support a type of

        gnu_unique_object.
        * doc/as.texinfo: Document new feature of .type directive.
        * NEWS: Mention support for gnu_unique_object symbol type.

        * common.h (STB_GNU_UNIQUE): Define.

        * NEWS: Mention the linker's support for symbols with a binding of
        STB_GNU_UNIQUE.

        * gas/elf/type.s: Add unique global symbol definition.
        * gas/elf/type.e: Add expected readelf output for global unique
        symbol.

        * elfcpp.h (enum STB): Add STB_GNU_UNIQUE.

        * readelf.c (get_symbol_binding): For Linux targeted files return
        UNIQUE for symbols with the STB_GNU_UNIQUE binding.
        * doc/binutils.texi: Document the meaning of the 'u' symbol
        binding in the output of nm and objdump --syms.

        * elf-bfd.h (struct elf_link_hash_entry): Add unique_global field.
        * elf.c (swap_out_syms): Set binding to STB_GNU_UNIQUE for symbols
        with the BSF_GNU_UNIQUE flag bit set.
        * elfcode.h (elf_slurp_symbol_table): Set the BSF_GNU_UNIQUE flag
        for symbols with STB_GNU_UNIQUE binding.
        * elflink.c (_bfd_elf_merge_symbol): Set unique_global for symbols
        with the STB_GNU_UNIQUE binding.
        (elf_link_add_object_symbols): Set the BSF_GNU_UNIQUE flag for
        symbols with STB_GNU_UNIQUE binding.  Set STB_GNU_UNIQUE for
        symbols with the unique_global field set.
        (elf_link_output_extsym): Set unique_global field for symbols with
        the STB_GNU_UNIQUE binding.
        * syms.c (struct bfd_symbol): Define BSF_GNU_UNIQUE flag bit.
        (bfd_print_symbol_vandf): Print a 'u' character for BSF_GNU_UNIQUE
        symbols.
        (bfd_decode_symclass): Return a 'u' character for BSF_GNU_UNIQUE
        symbols.
        * bfd-in2.h: Regenerate.

7 files changed, 64 insertions, 11 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 7987bbc..42dd8e3 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,24 @@
+2009-07-23  Ulrich Drepper  <drepper@redhat.com>
+
+	* elf-bfd.h (struct elf_link_hash_entry): Add unique_global field.
+	* elf.c (swap_out_syms): Set binding to STB_GNU_UNIQUE for symbols
+	with the BSF_GNU_UNIQUE flag bit set.
+	* elfcode.h (elf_slurp_symbol_table): Set the BSF_GNU_UNIQUE flag
+	for symbols with STB_GNU_UNIQUE binding.
+	* elflink.c (_bfd_elf_merge_symbol): Set unique_global for symbols
+	with the STB_GNU_UNIQUE binding.
+	(elf_link_add_object_symbols): Set the BSF_GNU_UNIQUE flag for
+	symbols with STB_GNU_UNIQUE binding.  Set STB_GNU_UNIQUE for
+	symbols with the unique_global field set.
+	(elf_link_output_extsym): Set unique_global field for symbols with
+	the STB_GNU_UNIQUE binding.
+	* syms.c (struct bfd_symbol): Define BSF_GNU_UNIQUE flag bit.
+	(bfd_print_symbol_vandf): Print a 'u' character for BSF_GNU_UNIQUE
+	symbols.
+	(bfd_decode_symclass): Return a 'u' character for BSF_GNU_UNIQUE
+	symbols.
+	* bfd-in2.h: Regenerate.
+
 2009-07-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	 * elflink.c (elf_link_output_extsym): Revert the last change.
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 5244b9a..562f833 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -4639,6 +4639,10 @@ typedef struct bfd_symbol
      calling the function that it points to.  BSF_FUNCTION must
      also be also set.  */
 #define BSF_GNU_INDIRECT_FUNCTION (1 << 22)
+  /* This symbol is a globally unique data object.  The dynamic linker
+     will make sure that in the entire process there is just one symbol
+     with this name and type in use.  BSF_OBJECT must also be set.  */
+#define BSF_GNU_UNIQUE         (1 << 23)
 
   flagword flags;
 
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index 1690def..8f70d79 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -178,6 +178,8 @@ struct elf_link_hash_entry
   /* Symbol is referenced with a relocation where C/C++ pointer equality
      matters.  */
   unsigned int pointer_equality_needed : 1;
+  /* Symbol is a unique global symbol.  */
+  unsigned int unique_global : 1;
 
   /* String table index in .dynstr if this is a dynamic symbol.  */
   unsigned long dynstr_index;
diff --git a/bfd/elf.c b/bfd/elf.c
index 19f2684..f27c607 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -6446,6 +6446,8 @@ Unable to find equivalent output section for symbol '%s' from section '%s'"),
 
 	  if (flags & BSF_LOCAL)
 	    bind = STB_LOCAL;
+	  else if (flags & BSF_GNU_UNIQUE)
+	    bind = STB_GNU_UNIQUE;
 	  else if (flags & BSF_WEAK)
 	    bind = STB_WEAK;
 	  else if (flags & BSF_GLOBAL)
diff --git a/bfd/elfcode.h b/bfd/elfcode.h
index 024ead4..10aa131 100644
--- a/bfd/elfcode.h
+++ b/bfd/elfcode.h
@@ -1,6 +1,6 @@
 /* ELF executable support for BFD.
    Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
+   2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
    Free Software Foundation, Inc.
 
    Written by Fred Fish @ Cygnus Support, from information published
@@ -1282,6 +1282,9 @@ elf_slurp_symbol_table (bfd *abfd, asymbol **symptrs, bfd_boolean dynamic)
 	    case STB_WEAK:
 	      sym->symbol.flags |= BSF_WEAK;
 	      break;
+	    case STB_GNU_UNIQUE:
+	      sym->symbol.flags |= BSF_GNU_UNIQUE;
+	      break;
 	    }
 
 	  switch (ELF_ST_TYPE (isym->st_info))
diff --git a/bfd/elflink.c b/bfd/elflink.c
index f9b577c..a117063 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -1248,6 +1248,9 @@ _bfd_elf_merge_symbol (bfd *abfd,
   oldweak = (h->root.type == bfd_link_hash_defweak
 	     || h->root.type == bfd_link_hash_undefweak);
 
+  if (bind == STB_GNU_UNIQUE)
+    h->unique_global = 1;
+
   /* If a new weak symbol definition comes from a regular file and the
      old symbol comes from a dynamic library, we treat the new one as
      strong.  Similarly, an old weak symbol definition from a regular
@@ -3871,24 +3874,31 @@ error_free_dyn:
       common = bed->common_definition (isym);
 
       bind = ELF_ST_BIND (isym->st_info);
-      if (bind == STB_LOCAL)
+      switch (bind)
 	{
+	case STB_LOCAL:
 	  /* This should be impossible, since ELF requires that all
 	     global symbols follow all local symbols, and that sh_info
 	     point to the first global symbol.  Unfortunately, Irix 5
 	     screws this up.  */
 	  continue;
-	}
-      else if (bind == STB_GLOBAL)
-	{
+
+	case STB_GLOBAL:
 	  if (isym->st_shndx != SHN_UNDEF && !common)
 	    flags = BSF_GLOBAL;
-	}
-      else if (bind == STB_WEAK)
-	flags = BSF_WEAK;
-      else
-	{
+	  break;
+
+	case STB_WEAK:
+	  flags = BSF_WEAK;
+	  break;
+
+	case STB_GNU_UNIQUE:
+	  flags = BSF_GNU_UNIQUE;
+	  break;
+
+	default:
 	  /* Leave it up to the processor backend.  */
+	  break;
 	}
 
       if (isym->st_shndx == SHN_UNDEF)
@@ -4140,7 +4150,9 @@ error_free_dyn:
       while (h->root.type == bfd_link_hash_indirect
 	     || h->root.type == bfd_link_hash_warning)
 	h = (struct elf_link_hash_entry *) h->root.u.i.link;
+
       *sym_hash = h;
+      h->unique_global = (flags & BSF_GNU_UNIQUE) != 0;
 
       new_weakdef = FALSE;
       if (dynamic
@@ -8571,6 +8583,8 @@ elf_link_output_extsym (struct elf_link_hash_entry *h, void *data)
   sym.st_other = h->other;
   if (h->forced_local)
     sym.st_info = ELF_ST_INFO (STB_LOCAL, h->type);
+  else if (h->unique_global)
+    sym.st_info = ELF_ST_INFO (STB_GNU_UNIQUE, h->type);
   else if (h->root.type == bfd_link_hash_undefweak
 	   || h->root.type == bfd_link_hash_defweak)
     sym.st_info = ELF_ST_INFO (STB_WEAK, h->type);
diff --git a/bfd/syms.c b/bfd/syms.c
index 6abb929..e4258b5 100644
--- a/bfd/syms.c
+++ b/bfd/syms.c
@@ -302,6 +302,10 @@ CODE_FRAGMENT
 .     calling the function that it points to.  BSF_FUNCTION must
 .     also be also set.  *}
 .#define BSF_GNU_INDIRECT_FUNCTION (1 << 22)
+.  {* This symbol is a globally unique data object.  The dynamic linker
+.     will make sure that in the entire process there is just one symbol
+.     with this name and type in use.  BSF_OBJECT must also be set.  *}
+.#define BSF_GNU_UNIQUE		(1 << 23)
 .
 .  flagword flags;
 .
@@ -485,7 +489,8 @@ bfd_print_symbol_vandf (bfd *abfd, void *arg, asymbol *symbol)
   fprintf (file, " %c%c%c%c%c%c%c",
 	   ((type & BSF_LOCAL)
 	    ? (type & BSF_GLOBAL) ? '!' : 'l'
-	    : (type & BSF_GLOBAL) ? 'g' : ' '),
+	    : (type & BSF_GLOBAL) ? 'g'
+	    : (type & BSF_GNU_UNIQUE) ? 'u' : ' '),
 	   (type & BSF_WEAK) ? 'w' : ' ',
 	   (type & BSF_CONSTRUCTOR) ? 'C' : ' ',
 	   (type & BSF_WARNING) ? 'W' : ' ',
@@ -686,6 +691,8 @@ bfd_decode_symclass (asymbol *symbol)
       else
 	return 'W';
     }
+  if (symbol->flags & BSF_GNU_UNIQUE)
+    return 'u';
   if (!(symbol->flags & (BSF_GLOBAL | BSF_LOCAL)))
     return '?';