Properly implement STT_COMMON

The BFD configure option, --enable-elf-stt-common, can't be to used to
verify STT_COMMON implementation with the normal binutils build.  Instead,
this patch removes it from BFD.  It adds --elf-stt-common=[no|yes] to ELF
assembler/objcopy and adds -z common/-z nocommon to ld.

A configure option, --enable-elf-stt-common, is added to gas to specify
whether ELF assembler should generate common symbols with the STT_COMMON
type by default.

Since BSF_KEEP_G is never used, it is renamed to BSF_ELF_COMMON for ELF
common symbols.

bfd/

	PR ld/19645
	* bfd.c (bfd): Change flags to 20 bits.
	(BFD_CONVERT_ELF_COMMON): New.
	(BFD_USE_ELF_STT_COMMON): Likewise.
	(BFD_FLAGS_SAVED): Add BFD_CONVERT_ELF_COMMON and
	BFD_USE_ELF_STT_COMMON.
	(BFD_FLAGS_FOR_BFD_USE_MASK): Likewise.
	* configure.ac: Remove --enable-elf-stt-common.
	* elf.c (swap_out_syms): Choose STT_COMMON or STT_OBJECT for
	common symbol depending on BFD_CONVERT_ELF_COMMON and
	BFD_USE_ELF_STT_COMMON.
	* elfcode.h (elf_slurp_symbol_table): Set BSF_ELF_COMMON for
	STT_COMMON.
	* elflink.c (bfd_elf_link_mark_dynamic_symbol): Also check
	STT_COMMON.
	(elf_link_convert_common_type): New function.
	(elf_link_output_extsym): Choose STT_COMMON or STT_OBJECT for
	common symbol depending on BFD_CONVERT_ELF_COMMON and
	BFD_USE_ELF_STT_COMMON.  Set sym.st_info after sym.st_shndx.
	* elfxx-target.h (TARGET_BIG_SYM): Add BFD_CONVERT_ELF_COMMON
	and BFD_USE_ELF_STT_COMMON to object_flags.
	(TARGET_LITTLE_SYM): Likewise.
	* syms.c (BSF_KEEP_G): Renamed to ...
	(BSF_ELF_COMMON): This.
	* bfd-in2.h: Regenerated.
	* config.in: Likewise.
	* configure: Likewise.

binutils/

	PR ld/19645
	* NEWS: Mention --elf-stt-common= for objcopy.
	* doc/binutils.texi: Document --elf-stt-common= for objcopy.
	* objcopy.c (do_elf_stt_common): New.
	(command_line_switch): Add OPTION_ELF_STT_COMMON.
	(copy_options): Add --elf-stt-common=.
	(copy_usage): Add --elf-stt-common=.
	(copy_object): Also check do_elf_stt_common for ELF targets.
	(copy_file): Handle do_elf_stt_common.
	(copy_main): Handle OPTION_ELF_STT_COMMON.
	* readelf.c (apply_relocations): Support STT_COMMON.
	* testsuite/binutils-all/common-1.s: New file.
	* testsuite/binutils-all/common-1a.d: Likewise.
	* testsuite/binutils-all/common-1b.d: Likewise.
	* testsuite/binutils-all/common-1c.d: Likewise.
	* testsuite/binutils-all/common-1d.d: Likewise.
	* testsuite/binutils-all/common-1e.d: Likewise.
	* testsuite/binutils-all/common-1f.d: Likewise.
	* testsuite/binutils-all/common-2.s: Likewise.
	* testsuite/binutils-all/common-2a.d: Likewise.
	* testsuite/binutils-all/common-2b.d: Likewise.
	* testsuite/binutils-all/common-2c.d: Likewise.
	* testsuite/binutils-all/common-2d.d: Likewise.
	* testsuite/binutils-all/common-2e.d: Likewise.
	* testsuite/binutils-all/common-2f.d: Likewise.
	* testsuite/binutils-all/objcopy.exp
	(objcopy_test_elf_common_symbols): New proc.
	Run objcopy_test_elf_common_symbols for ELF targets

gas/

	PR ld/19645
	* NEWS: Mention --enable-elf-stt-common and --elf-stt-common=
	for ELF assemblers.
	* as.c (flag_use_elf_stt_common): New.
	(show_usage): Add --elf-stt-common=.
	(option_values): Add OPTION_ELF_STT_COMMON.
	(std_longopts): Add --elf-stt-common=.
	(parse_args): Handle --elf-stt-common=.
	* as.h (flag_use_elf_stt_common): New.
	* config.in: Regenerated.
	* configure: Likewise.
	* configure.ac: Add --enable-elf-stt-common and define
	DEFAULT_GENERATE_ELF_STT_COMMON.
	* gas/write.c (write_object_file): Set BFD_CONVERT_ELF_COMMON
	and BFD_USE_ELF_STT_COMMON if flag_use_elf_stt_common is set.
	* doc/as.texinfo: Document --elf-stt-common=.
	* testsuite/gas/elf/common3.s: New file.
	* testsuite/gas/elf/common3a.d: Likewise.
	* testsuite/gas/elf/common3b.d: Likewise.
	* testsuite/gas/elf/common4.s: Likewise.
	* testsuite/gas/elf/common4a.d: Likewise.
	* testsuite/gas/elf/common4b.d: Likewise.
	* testsuite/gas/i386/dw2-compress-3b.d: Likewise.
	* testsuite/gas/i386/dw2-compressed-3b.d: Likewise.
	* testsuite/gas/elf/elf.exp: Run common3a, common3b, common4a
	and common4b.
	* testsuite/gas/i386/dw2-compress-3.d: Renamed to ...
	* testsuite/gas/i386/dw2-compress-3a.d: This.  Pass
	--elf-stt-common=no to as.
	* testsuite/gas/i386/dw2-compressed-3.d: Renamed to ...
	* testsuite/gas/i386/dw2-compressed-3a.d: This.  Pass
	--elf-stt-common=no to as.
	* testsuite/gas/i386/i386.exp: Run dw2-compress-3a,
	dw2-compress-3b, dw2-compressed-3a and dw2-compressed-3b instead
	of dw2-compress-3 and dw2-compressed-3.

include/

	PR ld/19645
	* bfdlink.h (bfd_link_elf_stt_common): New enum.
	(bfd_link_info): Add elf_stt_common.

ld/

	PR ld/19645
	* NEWS: Mention -z common/-z nocommon for ELF targets.
	* emultempl/elf32.em (gld${EMULATION_NAME}_handle_option): Handle
	-z common and -z nocommon.
	* ld.texinfo: Document -z common/-z nocommon.
	* lexsup.c (elf_shlib_list_options): Add -z common/-z nocommon.
	* testsuite/ld-elf/tls_common.exp: Test --elf-stt-common=no and
	--elf-stt-common=yes with assembler.
	* testsuite/ld-elfcomm/common-1.s: New file.
	* testsuite/ld-elfcomm/common-1a.d: Likewise.
	* testsuite/ld-elfcomm/common-1b.d: Likewise.
	* testsuite/ld-elfcomm/common-1c.d: Likewise.
	* testsuite/ld-elfcomm/common-1d.d: Likewise.
	* testsuite/ld-elfcomm/common-1e.d: Likewise.
	* testsuite/ld-elfcomm/common-1f.d: Likewise.
	* testsuite/ld-elfcomm/common-2.s: Likewise.
	* testsuite/ld-elfcomm/common-2a.d: Likewise.
	* testsuite/ld-elfcomm/common-2b.d: Likewise.
	* testsuite/ld-elfcomm/common-2c.d: Likewise.
	* testsuite/ld-elfcomm/common-2d.d: Likewise.
	* testsuite/ld-elfcomm/common-2e.d: Likewise.
	* testsuite/ld-elfcomm/common-2f.d: Likewise.
	* testsuite/ld-elfcomm/common-3a.rd: Likewise.
	* testsuite/ld-elfcomm/common-3b.rd: Likewise.
	* testsuite/ld-i386/pr19645.d: Likewise.
	* testsuite/ld-i386/pr19645.s: Likewise.
	* testsuite/ld-x86-64/largecomm-1.s: Likewise.
	* testsuite/ld-x86-64/largecomm-1a.d: Likewise.
	* testsuite/ld-x86-64/largecomm-1b.d: Likewise.
	* testsuite/ld-x86-64/largecomm-1c.d: Likewise.
	* testsuite/ld-x86-64/largecomm-1d.d: Likewise.
	* testsuite/ld-x86-64/largecomm-1e.d: Likewise.
	* testsuite/ld-x86-64/largecomm-1f.d: Likewise.
	* testsuite/ld-x86-64/pr19645.d: Likewise.
	* testsuite/ld-x86-64/pr19645.s: Likewise.
	* testsuite/ld-elfcomm/elfcomm.exp: Test --elf-stt-common=yes
	with assembler.
	(assembler_generates_commons): Removed.
	Run -z common/-z nocommon tests.  Run *.d tests.
	* testsuite/ld-i386/i386.exp: Run pr19645.
	* testsuite/ld-x86-64/x86-64.exp: Likewise.
	* testsuite/ld-x86-64/dwarfreloc.exp: Test --elf-stt-common with
	assembler.  Test STT_COMMON with readelf.

1 files changed, 66 insertions, 19 deletions

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 993e9b9..0e3abff 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -525,8 +525,10 @@ bfd_elf_link_mark_dynamic_symbol (struct bfd_link_info *info,
 
   if ((info->dynamic_data
        && (h->type == STT_OBJECT
+	   || h->type == STT_COMMON
 	   || (sym != NULL
-	       && ELF_ST_TYPE (sym->st_info) == STT_OBJECT)))
+	       && (ELF_ST_TYPE (sym->st_info) == STT_OBJECT
+		   || ELF_ST_TYPE (sym->st_info) == STT_COMMON))))
       || (d != NULL
 	  && h->root.type == bfd_link_hash_new
 	  && (*d->match) (&d->head, NULL, h->root.root.string)))
@@ -9038,6 +9040,28 @@ elf_link_check_versioned_symbol (struct bfd_link_info *info,
   return FALSE;
 }
 
+/* Convert ELF common symbol TYPE.  */
+
+static int
+elf_link_convert_common_type (struct bfd_link_info *info, int type)
+{
+  /* Commom symbol can only appear in relocatable link.  */
+  if (!bfd_link_relocatable (info))
+    abort ();
+  switch (info->elf_stt_common)
+    {
+    case unchanged:
+      break;
+    case elf_stt_common:
+      type = STT_COMMON;
+      break;
+    case no_elf_stt_common:
+      type = STT_OBJECT;
+      break;
+    }
+  return type;
+}
+
 /* Add an external symbol to the symbol table.  This is called from
    the hash table traversal routine.  When generating a shared object,
    we go through the symbol table twice.  The first time we output
@@ -9057,6 +9081,7 @@ elf_link_output_extsym (struct bfd_hash_entry *bh, void *data)
   const struct elf_backend_data *bed;
   long indx;
   int ret;
+  unsigned int type;
   /* A symbol is bound locally if it is forced local or it is locally
      defined, hidden versioned, not referenced by shared library and
      not exported when linking executable.  */
@@ -9191,35 +9216,21 @@ elf_link_output_extsym (struct bfd_hash_entry *bh, void *data)
 	   && (h->root.u.undef.abfd->flags & BFD_PLUGIN) != 0)
     strip = TRUE;
 
+  type = h->type;
+
   /* If we're stripping it, and it's not a dynamic symbol, there's
      nothing else to do.   However, if it is a forced local symbol or
      an ifunc symbol we need to give the backend finish_dynamic_symbol
      function a chance to make it dynamic.  */
   if (strip
       && h->dynindx == -1
-      && h->type != STT_GNU_IFUNC
+      && type != STT_GNU_IFUNC
       && !h->forced_local)
     return TRUE;
 
   sym.st_value = 0;
   sym.st_size = h->size;
   sym.st_other = h->other;
-  if (local_bind)
-    {
-      sym.st_info = ELF_ST_INFO (STB_LOCAL, h->type);
-      /* Turn off visibility on local symbol.  */
-      sym.st_other &= ~ELF_ST_VISIBILITY (-1);
-    }
-  /* Set STB_GNU_UNIQUE only if symbol is defined in regular object.  */
-  else if (h->unique_global && h->def_regular)
-    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);
-  else
-    sym.st_info = ELF_ST_INFO (STB_GLOBAL, h->type);
-  sym.st_target_internal = h->target_internal;
-
   switch (h->root.type)
     {
     default:
@@ -9294,6 +9305,42 @@ elf_link_output_extsym (struct bfd_hash_entry *bh, void *data)
       return TRUE;
     }
 
+  if (type == STT_COMMON || type == STT_OBJECT)
+    switch (h->root.type)
+      {
+      case bfd_link_hash_common:
+	type = elf_link_convert_common_type (flinfo->info, type);
+	break;
+      case bfd_link_hash_defined:
+      case bfd_link_hash_defweak:
+	if (bed->common_definition (&sym))
+	  type = elf_link_convert_common_type (flinfo->info, type);
+	else
+	  type = STT_OBJECT;
+	break;
+      case bfd_link_hash_undefined:
+      case bfd_link_hash_undefweak:
+	break;
+      default:
+	abort ();
+      }
+
+  if (local_bind)
+    {
+      sym.st_info = ELF_ST_INFO (STB_LOCAL, type);
+      /* Turn off visibility on local symbol.  */
+      sym.st_other &= ~ELF_ST_VISIBILITY (-1);
+    }
+  /* Set STB_GNU_UNIQUE only if symbol is defined in regular object.  */
+  else if (h->unique_global && h->def_regular)
+    sym.st_info = ELF_ST_INFO (STB_GNU_UNIQUE, 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, type);
+  else
+    sym.st_info = ELF_ST_INFO (STB_GLOBAL, type);
+  sym.st_target_internal = h->target_internal;
+
   /* Give the processor backend a chance to tweak the symbol value,
      and also to finish up anything that needs to be done for this
      symbol.  FIXME: Not calling elf_backend_finish_dynamic_symbol for
@@ -9330,7 +9377,7 @@ elf_link_output_extsym (struct bfd_hash_entry *bh, void *data)
 	  || ELF_ST_BIND (sym.st_info) == STB_WEAK))
     {
       int bindtype;
-      unsigned int type = ELF_ST_TYPE (sym.st_info);
+      type = ELF_ST_TYPE (sym.st_info);
 
       /* Turn an undefined IFUNC symbol into a normal FUNC symbol. */
       if (type == STT_GNU_IFUNC)