Fix ARM fail of gap test

ld-elf/gap test was failing due to the ARM backend attempting to output
arch symbols when ld -s (strip all symbols) is in force.  This patch
stops that happening and tidies the code a little.

	PR 17842
	* elflink.c (elf_link_output_sym): Assert elf_onesymtab set.
	(bfd_elf_final_link): Always create a symbol table when emit_relocs.
	Don't assign symtab file position unless symbols will be output.
	Merge blocks with condition in common.  Don't call
	elf_backend_output_arch_local_syms or elf_backend_output_arch_syms
	unless other symbols are output.  Move assignment of symtab_shndx
	file position.  Localize variable.

bfd/ChangeLog

@@ -1,3 +1,14 @@
+2015-01-15  Alan Modra  <amodra@gmail.com>
+
+	PR 17842
+	* elflink.c (elf_link_output_sym): Assert elf_onesymtab set.
+	(bfd_elf_final_link): Always create a symbol table when emit_relocs.
+	Don't assign symtab file position unless symbols will be output.
+	Merge blocks with condition in common.  Don't call
+	elf_backend_output_arch_local_syms or elf_backend_output_arch_syms
+	unless other symbols are output.  Move assignment of symtab_shndx
+	file position.  Localize variable.
+
 2015-01-14  Jiong Wang  <jiong.wang@arm.com>
 
 	* elf32-arm.c (elf32_arm_final_link_relocate): Reject R_ARM_32/_NOI when

bfd/elflink.c

@@ -8568,6 +8568,8 @@ elf_link_output_sym (struct elf_final_link_info *flinfo,
      struct elf_link_hash_entry *);
   const struct elf_backend_data *bed;
 
+  BFD_ASSERT (elf_onesymtab (flinfo->output_bfd));
+
   bed = get_elf_backend_data (flinfo->output_bfd);
   output_symbol_hook = bed->elf_backend_link_output_symbol_hook;
   if (output_symbol_hook != NULL)
@@ -10609,7 +10611,6 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   bfd_size_type max_internal_reloc_count;
   bfd_size_type max_sym_count;
   bfd_size_type max_sym_shndx_count;
-  file_ptr off;
   Elf_Internal_Sym elfsym;
   unsigned int i;
   Elf_Internal_Shdr *symtab_hdr;
@@ -10844,7 +10845,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   /* Figure out the file positions for everything but the symbol table
      and the relocs.  We set symcount to force assign_section_numbers
      to create a symbol table.  */
-  bfd_get_symcount (abfd) = info->strip == strip_all ? 0 : 1;
+  bfd_get_symcount (abfd) = info->strip != strip_all || emit_relocs;
   BFD_ASSERT (! abfd->output_has_begun);
   if (! _bfd_elf_compute_section_file_positions (abfd, info))
     goto error_return;
@@ -10885,13 +10886,6 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   /* sh_offset is set just below.  */
   symtab_hdr->sh_addralign = (bfd_vma) 1 << bed->s->log_file_align;
 
-  off = elf_next_file_pos (abfd);
-  off = _bfd_elf_assign_file_position_for_section (symtab_hdr, off, TRUE);
-
-  /* Note that at this point elf_next_file_pos (abfd) is
-     incorrect.  We do not yet know the size of the .symtab section.
-     We correct next_file_pos below, after we do know the size.  */
-
   /* Allocate a buffer to hold swapped out symbols.  This is to avoid
      continuously seeking to the right position in the file.  */
   if (! info->keep_memory || max_sym_count < 20)
@@ -10914,11 +10908,18 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	goto error_return;
     }
 
+  if (info->strip != strip_all || emit_relocs)
+    {
+      file_ptr off = elf_next_file_pos (abfd);
+
+      _bfd_elf_assign_file_position_for_section (symtab_hdr, off, TRUE);
+
+      /* Note that at this point elf_next_file_pos (abfd) is
+	 incorrect.  We do not yet know the size of the .symtab section.
+	 We correct next_file_pos below, after we do know the size.  */
+
       /* Start writing out the symbol table.  The first symbol is always a
 	 dummy symbol.  */
-  if (info->strip != strip_all
-      || emit_relocs)
-    {
       elfsym.st_value = 0;
       elfsym.st_size = 0;
       elfsym.st_info = 0;
@@ -10928,16 +10929,13 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
       if (elf_link_output_sym (&flinfo, NULL, &elfsym, bfd_und_section_ptr,
 			       NULL) != 1)
 	goto error_return;
-    }
 
       /* Output a symbol for each section.  We output these even if we are
 	 discarding local symbols, since they are used for relocs.  These
 	 symbols have no names.  We store the index of each one in the
 	 index field of the section, so that we can find it again when
 	 outputting relocs.  */
-  if (info->strip != strip_all
+
-      || emit_relocs)
-    {
       elfsym.st_size = 0;
       elfsym.st_info = ELF_ST_INFO (STB_LOCAL, STT_SECTION);
       elfsym.st_other = 0;
@@ -11168,7 +11166,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* If backend needs to output some local symbols not present in the hash
      table, do it now.  */
-  if (bed->elf_backend_output_arch_local_syms)
+  if (bed->elf_backend_output_arch_local_syms
+      && (info->strip != strip_all || emit_relocs))
     {
       typedef int (*out_sym_func)
 	(void *, const char *, Elf_Internal_Sym *, asection *,
@@ -11278,7 +11277,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 
   /* If backend needs to output some symbols not present in the hash
      table, do it now.  */
-  if (bed->elf_backend_output_arch_syms)
+  if (bed->elf_backend_output_arch_syms
+      && (info->strip != strip_all || emit_relocs))
     {
       typedef int (*out_sym_func)
 	(void *, const char *, Elf_Internal_Sym *, asection *,
@@ -11294,7 +11294,12 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
     return FALSE;
 
   /* Now we know the size of the symtab section.  */
-  off += symtab_hdr->sh_size;
+  if (bfd_get_symcount (abfd) > 0)
+    {
+      /* Finish up and write out the symbol string table (.strtab)
+	 section.  */
+      Elf_Internal_Shdr *symstrtab_hdr;
+      file_ptr off = symtab_hdr->sh_offset + symtab_hdr->sh_size;
 
       symtab_shndx_hdr = &elf_tdata (abfd)->symtab_shndx_hdr;
       if (symtab_shndx_hdr->sh_name != 0)
@@ -11313,13 +11318,6 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	    return FALSE;
 	}
 
-
-  if (bfd_get_symcount (abfd) > 0)
-    {
-      /* Finish up and write out the symbol string table (.strtab)
-	 section.  */
-      Elf_Internal_Shdr *symstrtab_hdr;
-
       symstrtab_hdr = &elf_tdata (abfd)->strtab_hdr;
       /* sh_name was set in prep_headers.  */
       symstrtab_hdr->sh_type = SHT_STRTAB;
@@ -11600,6 +11598,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	    {
 	      /* The contents of the .dynstr section are actually in a
 		 stringtab.  */
+	      file_ptr off;
+
 	      off = elf_section_data (o->output_section)->this_hdr.sh_offset;
 	      if (bfd_seek (abfd, off, SEEK_SET) != 0
 		  || ! _bfd_elf_strtab_emit (abfd,