Use strtab with GC and suffix merging for .strtabusers/hjl/pr18451

This patch uses ELF strtab with GC and suffix merging support to create
ELF .strtab section.  There is some small memory overhead to use ELF
strtab:

==14928== HEAP SUMMARY:
==14928==     in use at exit: 3,276,318 bytes in 679 blocks
==14928==   total heap usage: 1,544 allocs, 865 frees, 15,259,146 bytes allocated

vs.

==14936== HEAP SUMMARY:
==14936==     in use at exit: 3,276,318 bytes in 679 blocks
==14936==   total heap usage: 1,532 allocs, 853 frees, 15,026,402 bytes allocated

when running:

./ld-new -m elf_x86_64 -o tmpdir/ld-partial.o -r ldgram.o ldlex-wrapper.o lexsup.o ldlang.o mri.o ldctor.o ldmain.o plugin.o ldwrite.o ldexp.o ldemul.o ldver.o ldmisc.o ldfile.o ldcref.o eelf_x86_64.o eelf32_x86_64.o eelf_i386.o eelf_iamcu.o ei386linux.o eelf_l1om.o eelf_k1om.o ldbuildid.o

The results are

  [32] .strtab STRTAB 0+ 3beff8 00407a 00 0 0 1

vs

  [32] .strtab STRTAB 0+ 3beff8 0041d8 00 0 0 1

It reduces the .strtab size by 350 bytes, about 2%

Saving on libc.so from glibc is much more since libc.so has many alias
symbols with the same suffix.  For x32 glibc,

 [82] .strtab STRTAB 0+ 81b348 0159e7 00 0 0 1

vs

 [82] .strtab STRTAB 0+ 81b8bc 019e72 00 0 0 1

It reduces the .strtab size by 17547 bytes, about 16%.

bfd/

	PR gas/18451
	* elf-bfd.h (elf_sym_strtab): New.
	(elf_link_hash_table): Add strtabcount, strtabsize and
	strtab.
	(_bfd_elf_stringtab_init): Removed.
	* elf.c (_bfd_elf_stringtab_init): Removed.
	(_bfd_elf_compute_section_file_positions): Replace
	bfd_strtab_hash/_bfd_elf_stringtab_init/_bfd_stringtab_free/
	_bfd_stringtab_size with
	elf_strtab_hash/_bfd_elf_strtab_init/_bfd_elf_strtab_free/
	_bfd_elf_strtab_size.  Use _bfd_elf_strtab_add,
	_bfd_elf_strtab_finalize and _bfd_elf_strtab_offset to get
	st_name.
	(swap_out_syms): Likewise.
	* elflink.c (elf_final_link_info): Replace bfd_strtab_hash
	with elf_strtab_hash.  Remove symbuf, symbuf_count,
	symbuf_size and shndxbuf_size.
	(elf_link_flush_output_syms): Removed.
	(elf_link_output_sym): Renamed to ...
	(elf_link_output_symstrtab): This.  Replace _bfd_stringtab_add
	with _bfd_elf_strtab_add.  Don't flush symbols to the file nor
	swap out symbols.
	(elf_link_swap_symbols_out): New.
	(elf_link_output_extsym): Replace elf_link_output_sym with
	elf_link_output_symstrtab.
	(elf_link_input_bfd): Likewise.
	(elf_final_link_free): Replace _bfd_stringtab_free with
	_bfd_elf_strtab_free.  Remove symbuf.
	(bfd_elf_final_link): Replace _bfd_elf_stringtab_init with
	_bfd_elf_strtab_init.  Don't set symbuf, symbuf_count,
	symbuf_size nor shndxbuf_size.  Initialize strtabsize and
	strtab.  Initialize symshndxbuf to -1 when number of sections
	>= 64K.  Replace elf_link_output_sym/elf_link_output_sym with
	elf_link_output_symstrtab/elf_link_output_symstrtab. Don't
	call elf_link_flush_output_syms.  Call _bfd_elf_strtab_finalize
	and elf_link_swap_symbols_out.  Replace _bfd_stringtab_size
	and _bfd_stringtab_emit with _bfd_elf_strtab_size and
	_bfd_elf_strtab_emit.

gas/testsuite/

	PR gas/18451
	* gas/elf/elf.exp: Run strtab.
	* gas/elf/strtab.d: New file.
	* gas/elf/strtab.s: Likewise.

ld/testsuite/

	PR gas/18451
	* ld-elf/strtab.d: New file.
	* ld-elf/strtab.s: Likewise.

8 files changed, 270 insertions, 174 deletions

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index e435e52cc02..15fd5258a53 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -444,6 +444,13 @@ enum elf_target_id
   GENERIC_ELF_DATA
 };
 
+struct elf_sym_strtab
+{
+  Elf_Internal_Sym sym;
+  unsigned long dest_index;
+  unsigned long destshndx_index;
+};
+
 /* ELF linker hash table.  */
 
 struct elf_link_hash_table
@@ -487,6 +494,17 @@ struct elf_link_hash_table
      section.  */
   struct elf_strtab_hash *dynstr;
 
+  /* The number of symbol strings found in the link which must be put
+     into the .strtab section.  */
+  bfd_size_type strtabcount;
+
+  /* The array size of the symbol string table, which becomes the
+     .strtab section.  */
+  bfd_size_type strtabsize;
+
+  /* The array of strings, which becomes the .strtab section.  */
+  struct elf_sym_strtab *strtab;
+
   /* The number of buckets in the hash table in the .hash section.
      This is based on the number of dynamic symbols.  */
   bfd_size_type bucketcount;
@@ -1955,8 +1973,6 @@ extern Elf_Internal_Sym *bfd_sym_from_r_symndx
   (struct sym_cache *, bfd *, unsigned long);
 extern asection *bfd_section_from_elf_index
   (bfd *, unsigned int);
-extern struct bfd_strtab_hash *_bfd_elf_stringtab_init
-  (void);
 
 extern struct elf_strtab_hash * _bfd_elf_strtab_init
   (void);
diff --git a/bfd/elf.c b/bfd/elf.c
index 619a640b275..e148a5f2750 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -51,7 +51,7 @@ SECTION
 static int elf_sort_sections (const void *, const void *);
 static bfd_boolean assign_file_positions_except_relocs (bfd *, struct bfd_link_info *);
 static bfd_boolean prep_headers (bfd *);
-static bfd_boolean swap_out_syms (bfd *, struct bfd_strtab_hash **, int) ;
+static bfd_boolean swap_out_syms (bfd *, struct elf_strtab_hash **, int) ;
 static bfd_boolean elf_read_notes (bfd *, file_ptr, bfd_size_type) ;
 static bfd_boolean elf_parse_notes (bfd *abfd, char *buf, size_t size,
 				    file_ptr offset);
@@ -1610,29 +1610,6 @@ bfd_elf_print_symbol (bfd *abfd,
       break;
     }
 }
-
-/* Allocate an ELF string table--force the first byte to be zero.  */
-
-struct bfd_strtab_hash *
-_bfd_elf_stringtab_init (void)
-{
-  struct bfd_strtab_hash *ret;
-
-  ret = _bfd_stringtab_init ();
-  if (ret != NULL)
-    {
-      bfd_size_type loc;
-
-      loc = _bfd_stringtab_add (ret, "", TRUE, FALSE);
-      BFD_ASSERT (loc == 0 || loc == (bfd_size_type) -1);
-      if (loc == (bfd_size_type) -1)
-	{
-	  _bfd_stringtab_free (ret);
-	  ret = NULL;
-	}
-    }
-  return ret;
-}
 
 /* ELF .o/exec file reading */
 
@@ -3742,7 +3719,7 @@ _bfd_elf_compute_section_file_positions (bfd *abfd,
   const struct elf_backend_data *bed = get_elf_backend_data (abfd);
   struct fake_section_arg fsargs;
   bfd_boolean failed;
-  struct bfd_strtab_hash *strtab = NULL;
+  struct elf_strtab_hash *strtab = NULL;
   Elf_Internal_Shdr *shstrtab_hdr;
   bfd_boolean need_symtab;
 
@@ -3827,9 +3804,9 @@ _bfd_elf_compute_section_file_positions (bfd *abfd,
       /* Now that we know where the .strtab section goes, write it
 	 out.  */
       if (bfd_seek (abfd, hdr->sh_offset, SEEK_SET) != 0
-	  || ! _bfd_stringtab_emit (abfd, strtab))
+	  || ! _bfd_elf_strtab_emit (abfd, strtab))
 	return FALSE;
-      _bfd_stringtab_free (strtab);
+      _bfd_elf_strtab_free (strtab);
     }
 
   abfd->output_has_begun = TRUE;
@@ -7065,18 +7042,21 @@ _bfd_elf_copy_private_symbol_data (bfd *ibfd,
 
 static bfd_boolean
 swap_out_syms (bfd *abfd,
-	       struct bfd_strtab_hash **sttp,
+	       struct elf_strtab_hash **sttp,
 	       int relocatable_p)
 {
   const struct elf_backend_data *bed;
   int symcount;
   asymbol **syms;
-  struct bfd_strtab_hash *stt;
+  struct elf_strtab_hash *stt;
   Elf_Internal_Shdr *symtab_hdr;
   Elf_Internal_Shdr *symtab_shndx_hdr;
   Elf_Internal_Shdr *symstrtab_hdr;
+  struct elf_sym_strtab *symstrtab;
   bfd_byte *outbound_syms;
   bfd_byte *outbound_shndx;
+  unsigned long outbound_syms_index;
+  unsigned long outbound_shndx_index;
   int idx;
   unsigned int num_locals;
   bfd_size_type amt;
@@ -7086,7 +7066,7 @@ swap_out_syms (bfd *abfd,
     return FALSE;
 
   /* Dump out the symtabs.  */
-  stt = _bfd_elf_stringtab_init ();
+  stt = _bfd_elf_strtab_init ();
   if (stt == NULL)
     return FALSE;
 
@@ -7102,16 +7082,29 @@ swap_out_syms (bfd *abfd,
   symstrtab_hdr = &elf_tdata (abfd)->strtab_hdr;
   symstrtab_hdr->sh_type = SHT_STRTAB;
 
+  /* Allocate buffer to swap out the .strtab section.  */
+  symstrtab = (struct elf_sym_strtab *) bfd_malloc ((symcount + 1)
+						    * sizeof (*symstrtab));
+  if (symstrtab == NULL)
+    {
+      _bfd_elf_strtab_free (stt);
+      return FALSE;
+    }
+
   outbound_syms = (bfd_byte *) bfd_alloc2 (abfd, 1 + symcount,
                                            bed->s->sizeof_sym);
   if (outbound_syms == NULL)
     {
-      _bfd_stringtab_free (stt);
+error_return:
+      _bfd_elf_strtab_free (stt);
+      free (symstrtab);
       return FALSE;
     }
   symtab_hdr->contents = outbound_syms;
+  outbound_syms_index = 0;
 
   outbound_shndx = NULL;
+  outbound_shndx_index = 0;
   symtab_shndx_hdr = &elf_tdata (abfd)->symtab_shndx_hdr;
   if (symtab_shndx_hdr->sh_name != 0)
     {
@@ -7119,10 +7112,7 @@ swap_out_syms (bfd *abfd,
       outbound_shndx =  (bfd_byte *)
           bfd_zalloc2 (abfd, 1 + symcount, sizeof (Elf_External_Sym_Shndx));
       if (outbound_shndx == NULL)
-	{
-	  _bfd_stringtab_free (stt);
-	  return FALSE;
-	}
+	goto error_return;
 
       symtab_shndx_hdr->contents = outbound_shndx;
       symtab_shndx_hdr->sh_type = SHT_SYMTAB_SHNDX;
@@ -7142,10 +7132,12 @@ swap_out_syms (bfd *abfd,
     sym.st_other = 0;
     sym.st_shndx = SHN_UNDEF;
     sym.st_target_internal = 0;
-    bed->s->swap_symbol_out (abfd, &sym, outbound_syms, outbound_shndx);
-    outbound_syms += bed->s->sizeof_sym;
+    symstrtab[0].sym = sym;
+    symstrtab[0].dest_index = outbound_syms_index;
+    symstrtab[0].destshndx_index = outbound_shndx_index;
+    outbound_syms_index++;
     if (outbound_shndx != NULL)
-      outbound_shndx += sizeof (Elf_External_Sym_Shndx);
+      outbound_shndx_index++;
   }
 
   name_local_sections
@@ -7153,7 +7145,7 @@ swap_out_syms (bfd *abfd,
        && bed->elf_backend_name_local_section_symbols (abfd));
 
   syms = bfd_get_outsymbols (abfd);
-  for (idx = 0; idx < symcount; idx++)
+  for (idx = 0; idx < symcount;)
     {
       Elf_Internal_Sym sym;
       bfd_vma value = syms[idx]->value;
@@ -7165,18 +7157,17 @@ swap_out_syms (bfd *abfd,
 	  && (flags & (BSF_SECTION_SYM | BSF_GLOBAL)) == BSF_SECTION_SYM)
 	{
 	  /* Local section symbols have no name.  */
-	  sym.st_name = 0;
+	  sym.st_name = (unsigned long) -1;
 	}
       else
 	{
-	  sym.st_name = (unsigned long) _bfd_stringtab_add (stt,
-							    syms[idx]->name,
-							    TRUE, FALSE);
+	  /* Call _bfd_elf_strtab_offset after _bfd_elf_strtab_finalize
+	     to get the final offset for st_name.  */
+	  sym.st_name
+	    = (unsigned long) _bfd_elf_strtab_add (stt, syms[idx]->name,
+						   FALSE);
 	  if (sym.st_name == (unsigned long) -1)
-	    {
-	      _bfd_stringtab_free (stt);
-	      return FALSE;
-	    }
+	    goto error_return;
 	}
 
       type_ptr = elf_symbol_from (abfd, syms[idx]);
@@ -7266,8 +7257,7 @@ Unable to find equivalent output section for symbol '%s' from section '%s'"),
 					  syms[idx]->name ? syms[idx]->name : "<Local sym>",
 					  sec->name);
 		      bfd_set_error (bfd_error_invalid_operation);
-		      _bfd_stringtab_free (stt);
-		      return FALSE;
+		      goto error_return;
 		    }
 
 		  shndx = _bfd_elf_section_from_bfd_section (abfd, sec2);
@@ -7353,14 +7343,40 @@ Unable to find equivalent output section for symbol '%s' from section '%s'"),
 	  sym.st_target_internal = 0;
 	}
 
-      bed->s->swap_symbol_out (abfd, &sym, outbound_syms, outbound_shndx);
-      outbound_syms += bed->s->sizeof_sym;
+      idx++;
+      symstrtab[idx].sym = sym;
+      symstrtab[idx].dest_index = outbound_syms_index;
+      symstrtab[idx].destshndx_index = outbound_shndx_index;
+
+      outbound_syms_index++;
       if (outbound_shndx != NULL)
-	outbound_shndx += sizeof (Elf_External_Sym_Shndx);
+	outbound_shndx_index++;
     }
 
+  /* Finalize the .strtab section.  */
+  _bfd_elf_strtab_finalize (stt);
+
+  /* Swap out the .strtab section.  */
+  for (idx = 0; idx <= symcount; idx++)
+    {
+      struct elf_sym_strtab *elfsym = &symstrtab[idx];
+      if (elfsym->sym.st_name == (unsigned long) -1)
+	elfsym->sym.st_name = 0;
+      else
+	elfsym->sym.st_name = _bfd_elf_strtab_offset (stt,
+						      elfsym->sym.st_name);
+      bed->s->swap_symbol_out (abfd, &elfsym->sym,
+			       (outbound_syms
+				+ (elfsym->dest_index
+				   * bed->s->sizeof_sym)),
+			       (outbound_shndx
+				+ (elfsym->destshndx_index
+				   * sizeof (Elf_External_Sym_Shndx))));
+    }
+  free (symstrtab);
+
   *sttp = stt;
-  symstrtab_hdr->sh_size = _bfd_stringtab_size (stt);
+  symstrtab_hdr->sh_size = _bfd_elf_strtab_size (stt);
   symstrtab_hdr->sh_type = SHT_STRTAB;
 
   symstrtab_hdr->sh_flags = 0;
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 6efe1e4a61d..ca2f153a477 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -7403,7 +7403,7 @@ struct elf_final_link_info
   /* Output BFD.  */
   bfd *output_bfd;
   /* Symbol string table.  */
-  struct bfd_strtab_hash *symstrtab;
+  struct elf_strtab_hash *symstrtab;
   /* .dynsym section.  */
   asection *dynsym_sec;
   /* .hash section.  */
@@ -7430,16 +7430,8 @@ struct elf_final_link_info
   /* Array large enough to hold a section pointer for each local
      symbol of any input BFD.  */
   asection **sections;
-  /* Buffer to hold swapped out symbols.  */
-  bfd_byte *symbuf;
-  /* And one for symbol section indices.  */
+  /* Buffer for SHT_SYMTAB_SHNDX section.  */
   Elf_External_Sym_Shndx *symshndxbuf;
-  /* Number of swapped out symbols in buffer.  */
-  size_t symbuf_count;
-  /* Number of symbols which fit in symbuf.  */
-  size_t symbuf_size;
-  /* And same for symshndxbuf.  */
-  size_t shndxbuf_size;
   /* Number of STT_FILE syms seen.  */
   size_t filesym_count;
 };
@@ -8529,47 +8521,21 @@ elf_link_sort_relocs (bfd *abfd, struct bfd_link_info *info, asection **psec)
   return ret;
 }
 
-/* Flush the output symbols to the file.  */
-
-static bfd_boolean
-elf_link_flush_output_syms (struct elf_final_link_info *flinfo,
-			    const struct elf_backend_data *bed)
-{
-  if (flinfo->symbuf_count > 0)
-    {
-      Elf_Internal_Shdr *hdr;
-      file_ptr pos;
-      bfd_size_type amt;
-
-      hdr = &elf_tdata (flinfo->output_bfd)->symtab_hdr;
-      pos = hdr->sh_offset + hdr->sh_size;
-      amt = flinfo->symbuf_count * bed->s->sizeof_sym;
-      if (bfd_seek (flinfo->output_bfd, pos, SEEK_SET) != 0
-	  || bfd_bwrite (flinfo->symbuf, amt, flinfo->output_bfd) != amt)
-	return FALSE;
-
-      hdr->sh_size += amt;
-      flinfo->symbuf_count = 0;
-    }
-
-  return TRUE;
-}
-
-/* Add a symbol to the output symbol table.  */
+/* Add a symbol to the output symbol string table.  */
 
 static int
-elf_link_output_sym (struct elf_final_link_info *flinfo,
-		     const char *name,
-		     Elf_Internal_Sym *elfsym,
-		     asection *input_sec,
-		     struct elf_link_hash_entry *h)
-{
-  bfd_byte *dest;
-  Elf_External_Sym_Shndx *destshndx;
+elf_link_output_symstrtab (struct elf_final_link_info *flinfo,
+			   const char *name,
+			   Elf_Internal_Sym *elfsym,
+			   asection *input_sec,
+			   struct elf_link_hash_entry *h)
+{
   int (*output_symbol_hook)
     (struct bfd_link_info *, const char *, Elf_Internal_Sym *, asection *,
      struct elf_link_hash_entry *);
+  struct elf_link_hash_table *hash_table;
   const struct elf_backend_data *bed;
+  bfd_size_type strtabsize;
 
   BFD_ASSERT (elf_onesymtab (flinfo->output_bfd));
 
@@ -8582,49 +8548,119 @@ elf_link_output_sym (struct elf_final_link_info *flinfo,
 	return ret;
     }
 
-  if (name == NULL || *name == '\0')
-    elfsym->st_name = 0;
-  else if (input_sec->flags & SEC_EXCLUDE)
-    elfsym->st_name = 0;
+  if (name == NULL
+      || *name == '\0'
+      || (input_sec->flags & SEC_EXCLUDE))
+    elfsym->st_name = (unsigned long) -1;
   else
     {
-      elfsym->st_name = (unsigned long) _bfd_stringtab_add (flinfo->symstrtab,
-							    name, TRUE, FALSE);
+      /* Call _bfd_elf_strtab_offset after _bfd_elf_strtab_finalize
+	 to get the final offset for st_name.  */
+      elfsym->st_name
+	= (unsigned long) _bfd_elf_strtab_add (flinfo->symstrtab,
+					       name, FALSE);
       if (elfsym->st_name == (unsigned long) -1)
 	return 0;
     }
 
-  if (flinfo->symbuf_count >= flinfo->symbuf_size)
+  hash_table = elf_hash_table (flinfo->info);
+  strtabsize = hash_table->strtabsize;
+  if (strtabsize <= hash_table->strtabcount)
     {
-      if (! elf_link_flush_output_syms (flinfo, bed))
+      strtabsize += strtabsize;
+      hash_table->strtabsize = strtabsize;
+      strtabsize *= sizeof (*hash_table->strtab);
+      hash_table->strtab
+	= (struct elf_sym_strtab *) bfd_realloc (hash_table->strtab,
+						 strtabsize);
+      if (hash_table->strtab == NULL)
 	return 0;
     }
+  hash_table->strtab[hash_table->strtabcount].sym = *elfsym;
+  hash_table->strtab[hash_table->strtabcount].dest_index
+    = hash_table->strtabcount;
+  hash_table->strtab[hash_table->strtabcount].destshndx_index
+    = flinfo->symshndxbuf ? bfd_get_symcount (flinfo->output_bfd) : 0;
+
+  bfd_get_symcount (flinfo->output_bfd) += 1;
+  hash_table->strtabcount += 1;
+
+  return 1;
+}
+
+/* Swap symbols out to the symbol table and flush the output symbols to
+   the file.  */
 
-  dest = flinfo->symbuf + flinfo->symbuf_count * bed->s->sizeof_sym;
-  destshndx = flinfo->symshndxbuf;
-  if (destshndx != NULL)
+static bfd_boolean
+elf_link_swap_symbols_out (struct elf_final_link_info *flinfo)
+{
+  struct elf_link_hash_table *hash_table = elf_hash_table (flinfo->info);
+  bfd_size_type amt, i;
+  const struct elf_backend_data *bed;
+  bfd_byte *symbuf;
+  Elf_Internal_Shdr *hdr;
+  file_ptr pos;
+  bfd_boolean ret;
+
+  if (!hash_table->strtabcount)
+    return TRUE;
+
+  BFD_ASSERT (elf_onesymtab (flinfo->output_bfd));
+
+  bed = get_elf_backend_data (flinfo->output_bfd);
+
+  amt = bed->s->sizeof_sym * hash_table->strtabcount;
+  symbuf = (bfd_byte *) bfd_malloc (amt);
+  if (symbuf == NULL)
+    return FALSE;
+  
+  if (flinfo->symshndxbuf)
     {
-      if (bfd_get_symcount (flinfo->output_bfd) >= flinfo->shndxbuf_size)
+      amt = (sizeof (Elf_External_Sym_Shndx)
+	     * (bfd_get_symcount (flinfo->output_bfd)));
+      flinfo->symshndxbuf = (Elf_External_Sym_Shndx *) bfd_zmalloc (amt);
+      if (flinfo->symshndxbuf == NULL)
 	{
-	  bfd_size_type amt;
-
-	  amt = flinfo->shndxbuf_size * sizeof (Elf_External_Sym_Shndx);
-	  destshndx = (Elf_External_Sym_Shndx *) bfd_realloc (destshndx,
-							      amt * 2);
-	  if (destshndx == NULL)
-	    return 0;
-	  flinfo->symshndxbuf = destshndx;
-	  memset ((char *) destshndx + amt, 0, amt);
-	  flinfo->shndxbuf_size *= 2;
+	  free (symbuf);
+	  return FALSE;
 	}
-      destshndx += bfd_get_symcount (flinfo->output_bfd);
     }
 
-  bed->s->swap_symbol_out (flinfo->output_bfd, elfsym, dest, destshndx);
-  flinfo->symbuf_count += 1;
-  bfd_get_symcount (flinfo->output_bfd) += 1;
+  for (i = 0; i < hash_table->strtabcount; i++)
+    {
+      struct elf_sym_strtab *elfsym = &hash_table->strtab[i];
+      if (elfsym->sym.st_name == (unsigned long) -1)
+	elfsym->sym.st_name = 0;
+      else
+	elfsym->sym.st_name
+	  = (unsigned long) _bfd_elf_strtab_offset (flinfo->symstrtab,
+						    elfsym->sym.st_name);
+      bed->s->swap_symbol_out (flinfo->output_bfd, &elfsym->sym,
+			       ((bfd_byte *) symbuf
+				+ (elfsym->dest_index
+				   * bed->s->sizeof_sym)),
+			       (flinfo->symshndxbuf
+				+ elfsym->destshndx_index));
+    }
+
+  hdr = &elf_tdata (flinfo->output_bfd)->symtab_hdr;
+  pos = hdr->sh_offset + hdr->sh_size;
+  amt = hash_table->strtabcount * bed->s->sizeof_sym;
+  if (bfd_seek (flinfo->output_bfd, pos, SEEK_SET) == 0
+      && bfd_bwrite (symbuf, amt, flinfo->output_bfd) == amt)
+    {
+      hdr->sh_size += amt;
+      ret = TRUE;
+    }
+  else
+    ret = FALSE;
 
-  return 1;
+  free (symbuf);
+
+  free (hash_table->strtab);
+  hash_table->strtab = NULL;
+
+  return ret;
 }
 
 /* Return TRUE if the dynamic symbol SYM in ABFD is supported.  */
@@ -9250,15 +9286,16 @@ elf_link_output_extsym (struct bfd_hash_entry *bh, void *data)
       memset (&fsym, 0, sizeof (fsym));
       fsym.st_info = ELF_ST_INFO (STB_LOCAL, STT_FILE);
       fsym.st_shndx = SHN_ABS;
-      if (!elf_link_output_sym (eoinfo->flinfo, NULL, &fsym,
-				bfd_und_section_ptr, NULL))
+      if (!elf_link_output_symstrtab (eoinfo->flinfo, NULL, &fsym,
+				      bfd_und_section_ptr, NULL))
 	return FALSE;
 
       eoinfo->file_sym_done = TRUE;
     }
 
   indx = bfd_get_symcount (flinfo->output_bfd);
-  ret = elf_link_output_sym (flinfo, h->root.root.string, &sym, input_sec, h);
+  ret = elf_link_output_symstrtab (flinfo, h->root.root.string, &sym,
+				   input_sec, h);
   if (ret == 0)
     {
       eoinfo->failed = TRUE;
@@ -9551,10 +9588,11 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
 	  memset (&osym, 0, sizeof (osym));
 	  osym.st_info = ELF_ST_INFO (STB_LOCAL, STT_FILE);
 	  osym.st_shndx = SHN_ABS;
-	  if (!elf_link_output_sym (flinfo,
-				    (input_bfd->lto_output ? NULL
-				     : input_bfd->filename),
-				    &osym, bfd_abs_section_ptr, NULL))
+	  if (!elf_link_output_symstrtab (flinfo,
+					  (input_bfd->lto_output ? NULL
+					   : input_bfd->filename),
+					  &osym, bfd_abs_section_ptr,
+					  NULL))
 	    return FALSE;
 	}
 
@@ -9586,7 +9624,7 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
 	}
 
       indx = bfd_get_symcount (output_bfd);
-      ret = elf_link_output_sym (flinfo, name, &osym, isec, NULL);
+      ret = elf_link_output_symstrtab (flinfo, name, &osym, isec, NULL);
       if (ret == 0)
 	return FALSE;
       else if (ret == 1)
@@ -9669,7 +9707,8 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
 		  sym.st_value += o->output_offset;
 
 		  indx = bfd_get_symcount (output_bfd);
-		  ret = elf_link_output_sym (flinfo, name, &sym, o, NULL);
+		  ret = elf_link_output_symstrtab (flinfo, name, &sym, o,
+						   NULL);
 		  if (ret == 0)
 		    return FALSE;
 		  else if (ret == 1)
@@ -10144,8 +10183,9 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
 			    }
 
 			  indx = bfd_get_symcount (output_bfd);
-			  ret = elf_link_output_sym (flinfo, name, &sym, sec,
-						     NULL);
+			  ret = elf_link_output_symstrtab (flinfo, name,
+							   &sym, sec,
+							   NULL);
 			  if (ret == 0)
 			    return FALSE;
 			  else if (ret == 1)
@@ -10584,7 +10624,7 @@ elf_final_link_free (bfd *obfd, struct elf_final_link_info *flinfo)
   asection *o;
 
   if (flinfo->symstrtab != NULL)
-    _bfd_stringtab_free (flinfo->symstrtab);
+    _bfd_elf_strtab_free (flinfo->symstrtab);
   if (flinfo->contents != NULL)
     free (flinfo->contents);
   if (flinfo->external_relocs != NULL)
@@ -10601,8 +10641,6 @@ elf_final_link_free (bfd *obfd, struct elf_final_link_info *flinfo)
     free (flinfo->indices);
   if (flinfo->sections != NULL)
     free (flinfo->sections);
-  if (flinfo->symbuf != NULL)
-    free (flinfo->symbuf);
   if (flinfo->symshndxbuf != NULL)
     free (flinfo->symshndxbuf);
   for (o = obfd->sections; o != NULL; o = o->next)
@@ -10660,7 +10698,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 
   flinfo.info = info;
   flinfo.output_bfd = abfd;
-  flinfo.symstrtab = _bfd_elf_stringtab_init ();
+  flinfo.symstrtab = _bfd_elf_strtab_init ();
   if (flinfo.symstrtab == NULL)
     return FALSE;
 
@@ -10687,10 +10725,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
   flinfo.internal_syms = NULL;
   flinfo.indices = NULL;
   flinfo.sections = NULL;
-  flinfo.symbuf = NULL;
   flinfo.symshndxbuf = NULL;
-  flinfo.symbuf_count = 0;
-  flinfo.shndxbuf_size = 0;
   flinfo.filesym_count = 0;
 
   /* The object attributes have been merged.  Remove the input
@@ -10922,27 +10957,18 @@ 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;
 
-  /* 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)
-    flinfo.symbuf_size = 20;
-  else
-    flinfo.symbuf_size = max_sym_count;
-  amt = flinfo.symbuf_size;
-  amt *= bed->s->sizeof_sym;
-  flinfo.symbuf = (bfd_byte *) bfd_malloc (amt);
-  if (flinfo.symbuf == NULL)
+  if (max_sym_count < 20)
+    max_sym_count = 20;
+  elf_hash_table (info)->strtabsize = max_sym_count;
+  amt = max_sym_count * sizeof (struct elf_sym_strtab);
+  elf_hash_table (info)->strtab
+    = (struct elf_sym_strtab *) bfd_malloc (amt);
+  if (elf_hash_table (info)->strtab == NULL)
     goto error_return;
-  if (elf_numsections (abfd) > (SHN_LORESERVE & 0xFFFF))
-    {
-      /* Wild guess at number of output symbols.  realloc'd as needed.  */
-      amt = 2 * max_sym_count + elf_numsections (abfd) + 1000;
-      flinfo.shndxbuf_size = amt;
-      amt *= sizeof (Elf_External_Sym_Shndx);
-      flinfo.symshndxbuf = (Elf_External_Sym_Shndx *) bfd_zmalloc (amt);
-      if (flinfo.symshndxbuf == NULL)
-	goto error_return;
-    }
+  /* The real buffer will be allocated in elf_link_swap_symbols_out.  */
+  flinfo.symshndxbuf
+    = (elf_numsections (abfd) > (SHN_LORESERVE & 0xFFFF)
+       ? (Elf_External_Sym_Shndx *) -1 : NULL);
 
   if (info->strip != strip_all || emit_relocs)
     {
@@ -10962,8 +10988,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
       elfsym.st_other = 0;
       elfsym.st_shndx = SHN_UNDEF;
       elfsym.st_target_internal = 0;
-      if (elf_link_output_sym (&flinfo, NULL, &elfsym, bfd_und_section_ptr,
-			       NULL) != 1)
+      if (elf_link_output_symstrtab (&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
@@ -10986,7 +11012,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	      elfsym.st_shndx = i;
 	      if (!info->relocatable)
 		elfsym.st_value = o->vma;
-	      if (elf_link_output_sym (&flinfo, NULL, &elfsym, o, NULL) != 1)
+	      if (elf_link_output_symstrtab (&flinfo, NULL, &elfsym, o,
+					     NULL) != 1)
 		goto error_return;
 	    }
 	}
@@ -11200,7 +11227,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	 struct elf_link_hash_entry *);
 
       if (! ((*bed->elf_backend_output_arch_local_syms)
-	     (abfd, info, &flinfo, (out_sym_func) elf_link_output_sym)))
+	     (abfd, info, &flinfo,
+	      (out_sym_func) elf_link_output_symstrtab)))
 	return FALSE;
     }
 
@@ -11311,12 +11339,16 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
 	 struct elf_link_hash_entry *);
 
       if (! ((*bed->elf_backend_output_arch_syms)
-	     (abfd, info, &flinfo, (out_sym_func) elf_link_output_sym)))
+	     (abfd, info, &flinfo,
+	      (out_sym_func) elf_link_output_symstrtab)))
 	return FALSE;
     }
 
-  /* Flush all symbols to the file.  */
-  if (! elf_link_flush_output_syms (&flinfo, bed))
+  /* Finalize the .strtab section.  */
+  _bfd_elf_strtab_finalize (flinfo.symstrtab);
+
+  /* Swap out the .strtab section. */
+  if (!elf_link_swap_symbols_out (&flinfo))
     return FALSE;
 
   /* Now we know the size of the symtab section.  */
@@ -11349,7 +11381,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
       symstrtab_hdr->sh_type = SHT_STRTAB;
       symstrtab_hdr->sh_flags = 0;
       symstrtab_hdr->sh_addr = 0;
-      symstrtab_hdr->sh_size = _bfd_stringtab_size (flinfo.symstrtab);
+      symstrtab_hdr->sh_size = _bfd_elf_strtab_size (flinfo.symstrtab);
       symstrtab_hdr->sh_entsize = 0;
       symstrtab_hdr->sh_link = 0;
       symstrtab_hdr->sh_info = 0;
@@ -11361,7 +11393,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
       elf_next_file_pos (abfd) = off;
 
       if (bfd_seek (abfd, symstrtab_hdr->sh_offset, SEEK_SET) != 0
-	  || ! _bfd_stringtab_emit (abfd, flinfo.symstrtab))
+	  || ! _bfd_elf_strtab_emit (abfd, flinfo.symstrtab))
 	return FALSE;
     }
 
diff --git a/gas/testsuite/gas/elf/elf.exp b/gas/testsuite/gas/elf/elf.exp
index 47b5a21b030..ff19badefb8 100644
--- a/gas/testsuite/gas/elf/elf.exp
+++ b/gas/testsuite/gas/elf/elf.exp
@@ -209,6 +209,8 @@ if { [is_elf_format] } then {
     run_dump_test "common1"
     run_dump_test "common2"
 
+    run_dump_test "strtab"
+
 load_lib gas-dg.exp
 dg-init
 dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/err-*.s $srcdir/$subdir/warn-*.s]] "" ""
diff --git a/gas/testsuite/gas/elf/strtab.d b/gas/testsuite/gas/elf/strtab.d
new file mode 100644
index 00000000000..c6495d7262b
--- /dev/null
+++ b/gas/testsuite/gas/elf/strtab.d
@@ -0,0 +1,7 @@
+#readelf: -W -x .strtab
+#name: .strtab section
+
+#failif
+#...
+ +0x[0-9 ]+.*\.xxxx\..*
+#...
diff --git a/gas/testsuite/gas/elf/strtab.s b/gas/testsuite/gas/elf/strtab.s
new file mode 100644
index 00000000000..931d9ef31df
--- /dev/null
+++ b/gas/testsuite/gas/elf/strtab.s
@@ -0,0 +1,8 @@
+ .text
+.globl x; x:
+.globl xx; xx:
+.globl xxx; xxx:
+.globl xxxx; xxxx:
+.globl xxxxx; xxxxx:
+.globl xxxxxx; xxxxxx:
+	.byte 0
diff --git a/ld/testsuite/ld-elf/strtab.d b/ld/testsuite/ld-elf/strtab.d
new file mode 100644
index 00000000000..07977087725
--- /dev/null
+++ b/ld/testsuite/ld-elf/strtab.d
@@ -0,0 +1,7 @@
+#ld: -shared
+#readelf: -W -x .strtab
+
+#failif
+#...
+ +0x[0-9 ]+.*\.xxxx\..*
+#...
diff --git a/ld/testsuite/ld-elf/strtab.s b/ld/testsuite/ld-elf/strtab.s
new file mode 100644
index 00000000000..931d9ef31df
--- /dev/null
+++ b/ld/testsuite/ld-elf/strtab.s
@@ -0,0 +1,8 @@
+ .text
+.globl x; x:
+.globl xx; xx:
+.globl xxx; xxx:
+.globl xxxx; xxxx:
+.globl xxxxx; xxxxx:
+.globl xxxxxx; xxxxxx:
+	.byte 0