bfd/

	* libbfd-in.h (_bfd_merge_section): New.
	(_bfd_write_merged_section): New.
	(_bfd_merged_section_offset): New.
	* libbfd.h: Rebuilt.
	* linker.c (_bfd_generic_link_output_symbols): Handle
	discard_sec_merge.
	* aoutx.h (aout_link_write_symbols): Likewise.
	* pdp11.c (aout_link_write_symbols): Likewise.
	* elflink.h (elf_link_add_object_symbols): Call _bfd_merge_section.
	(elf_bfd_final_link): Adjust global symbols pointing into SEC_MERGE
	sections.
	(elf_link_sec_merge_syms): New.
	(elf_link_input_bfd): Call _bfd_merged_section_offset
	and _bfd_write_merged_section.
	Handle discard_sec_merge.
	* elf-bfd.h (struct elf_link_hash_table): Add merge_info
	field.
	(struct bfd_elf_section_data): Likewise.
	* elf.c (_bfd_elf_make_section_from_shdr): Set SEC_MERGE and
	SEC_STRINGS section flags and entsize from their ELF counterparts.
	(_bfd_elf_link_hash_table_init): Initialize merge_info.
	(elf_fake_sections): Set SHF_MERGE, SHF_STRINGS and sh_entsize
	from their BFD counterparts.
	* merge.c: New file.
	* Makefile.am: Add strtab.lo.
	* Makefile.in: Rebuilt.
include/
	* bfdlink.h (bfd_link_discard): Add discard_sec_merge.
gas/
	* config/obj-elf.c (obj_elf_change_section): Add entsize argument,
	handle SHF_MERGE and SHF_STRINGS.
	(obj_elf_parse_section_letters): Set SHF_MERGE and SHF_STRINGS.
	(obj_elf_section): Allow additional argument specifying entity size.
	* write.c (adjust_reloc_syms): Keep relocations against local symbols
	in SEC_MERGE sections.
ld/
	* ldmain.c (main): Default to discard_sec_merge.
	* lexsup.c (OPTION_DISCARD_NONE): Define.
	(ld_options): Add --discard-none.
	(parse_args): Handle OPTION_DISCARD_NONE.
	* ldlang.c (wild_doit): SEC_MERGE should be set in the output
	section only if SEC_MERGE and SEC_STRINGS flags and entsize of
	all its input sections match.

13 files changed, 787 insertions, 15 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index f16feaa61a8..623d29660bb 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,32 @@
+2001-04-13  Jakub Jelinek  <jakub@redhat.com>
+
+	* libbfd-in.h (_bfd_merge_section): New.
+	(_bfd_write_merged_section): New.
+	(_bfd_merged_section_offset): New.
+	* libbfd.h: Rebuilt.
+	* linker.c (_bfd_generic_link_output_symbols): Handle
+	discard_sec_merge.
+	* aoutx.h (aout_link_write_symbols): Likewise.
+	* pdp11.c (aout_link_write_symbols): Likewise.
+	* elflink.h (elf_link_add_object_symbols): Call _bfd_merge_section.
+	(elf_bfd_final_link): Adjust global symbols pointing into SEC_MERGE
+	sections.
+	(elf_link_sec_merge_syms): New.
+	(elf_link_input_bfd): Call _bfd_merged_section_offset
+	and _bfd_write_merged_section.
+	Handle discard_sec_merge.
+	* elf-bfd.h (struct elf_link_hash_table): Add merge_info
+	field.
+	(struct bfd_elf_section_data): Likewise.
+	* elf.c (_bfd_elf_make_section_from_shdr): Set SEC_MERGE and
+	SEC_STRINGS section flags and entsize from their ELF counterparts.
+	(_bfd_elf_link_hash_table_init): Initialize merge_info.
+	(elf_fake_sections): Set SHF_MERGE, SHF_STRINGS and sh_entsize
+	from their BFD counterparts.
+	* merge.c: New file.
+	* Makefile.am: Add strtab.lo.
+	* Makefile.in: Rebuilt.
+
 2001-04-09  Hans-Peter Nilsson  <hp@axis.com>
 
 	* elflink.h (elf_fix_symbol_flags): For non-default visibilities,
diff --git a/bfd/Makefile.am b/bfd/Makefile.am
index c75439c82c3..0eeb3b44cb6 100644
--- a/bfd/Makefile.am
+++ b/bfd/Makefile.am
@@ -30,14 +30,14 @@ BFD_LIBS = \
 	format.lo init.lo libbfd.lo opncls.lo reloc.lo \
 	section.lo syms.lo targets.lo hash.lo linker.lo \
 	srec.lo binary.lo tekhex.lo ihex.lo stabs.lo stab-syms.lo \
-	dwarf2.lo
+	merge.lo dwarf2.lo
 
 BFD_LIBS_CFILES = \
 	archive.c archures.c bfd.c cache.c coffgen.c corefile.c \
 	format.c init.c libbfd.c opncls.c reloc.c \
 	section.c syms.c targets.c hash.c linker.c \
 	srec.c binary.c tekhex.c ihex.c stabs.c stab-syms.c \
-	dwarf2.c
+	merge.c dwarf2.c
 
 # This list is alphabetized to make it easier to keep in sync
 # with the decls and initializer in archures.c.
@@ -780,6 +780,7 @@ stabs.lo: stabs.c $(INCDIR)/filenames.h $(INCDIR)/aout/stab_gnu.h \
   $(INCDIR)/aout/stab.def
 stab-syms.lo: stab-syms.c libaout.h $(INCDIR)/bfdlink.h \
   $(INCDIR)/aout/aout64.h $(INCDIR)/aout/stab.def
+merge.lo: merge.c $(INCDIR)/filenames.h
 dwarf2.lo: dwarf2.c $(INCDIR)/filenames.h $(INCDIR)/libiberty.h \
   elf-bfd.h $(INCDIR)/elf/common.h $(INCDIR)/elf/internal.h \
   $(INCDIR)/elf/external.h $(INCDIR)/bfdlink.h $(INCDIR)/elf/dwarf2.h
diff --git a/bfd/Makefile.in b/bfd/Makefile.in
index d85434616f0..670cd1b1225 100644
--- a/bfd/Makefile.in
+++ b/bfd/Makefile.in
@@ -144,10 +144,10 @@ BFD_H = bfd.h
 # for the debugger, so if you are downloading things as S-records you
 # need two copies of the executable, one to download and one for the
 # debugger).
-BFD_LIBS =  	archive.lo archures.lo bfd.lo cache.lo coffgen.lo corefile.lo 	format.lo init.lo libbfd.lo opncls.lo reloc.lo 	section.lo syms.lo targets.lo hash.lo linker.lo 	srec.lo binary.lo tekhex.lo ihex.lo stabs.lo stab-syms.lo 	dwarf2.lo
+BFD_LIBS =  	archive.lo archures.lo bfd.lo cache.lo coffgen.lo corefile.lo 	format.lo init.lo libbfd.lo opncls.lo reloc.lo 	section.lo syms.lo targets.lo hash.lo linker.lo 	srec.lo binary.lo tekhex.lo ihex.lo stabs.lo stab-syms.lo 	merge.lo dwarf2.lo
 
 
-BFD_LIBS_CFILES =  	archive.c archures.c bfd.c cache.c coffgen.c corefile.c 	format.c init.c libbfd.c opncls.c reloc.c 	section.c syms.c targets.c hash.c linker.c 	srec.c binary.c tekhex.c ihex.c stabs.c stab-syms.c 	dwarf2.c
+BFD_LIBS_CFILES =  	archive.c archures.c bfd.c cache.c coffgen.c corefile.c 	format.c init.c libbfd.c opncls.c reloc.c 	section.c syms.c targets.c hash.c linker.c 	srec.c binary.c tekhex.c ihex.c stabs.c stab-syms.c 	merge.c dwarf2.c
 
 
 # This list is alphabetized to make it easier to keep in sync
@@ -261,7 +261,7 @@ LTLIBRARIES =  $(lib_LTLIBRARIES)
 libbfd_la_OBJECTS =  archive.lo archures.lo bfd.lo cache.lo coffgen.lo \
 corefile.lo format.lo init.lo libbfd.lo opncls.lo reloc.lo section.lo \
 syms.lo targets.lo hash.lo linker.lo srec.lo binary.lo tekhex.lo \
-ihex.lo stabs.lo stab-syms.lo dwarf2.lo
+ihex.lo stabs.lo stab-syms.lo merge.lo dwarf2.lo
 CFLAGS = @CFLAGS@
 COMPILE = $(CC) $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
 LTCOMPILE = $(LIBTOOL) --mode=compile $(CC) $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
@@ -887,6 +887,7 @@ stabs.lo: stabs.c $(INCDIR)/filenames.h $(INCDIR)/aout/stab_gnu.h \
   $(INCDIR)/aout/stab.def
 stab-syms.lo: stab-syms.c libaout.h $(INCDIR)/bfdlink.h \
   $(INCDIR)/aout/aout64.h $(INCDIR)/aout/stab.def
+merge.lo: merge.c $(INCDIR)/filenames.h
 dwarf2.lo: dwarf2.c $(INCDIR)/filenames.h $(INCDIR)/libiberty.h \
   elf-bfd.h $(INCDIR)/elf/common.h $(INCDIR)/elf/internal.h \
   $(INCDIR)/elf/external.h $(INCDIR)/bfdlink.h $(INCDIR)/elf/dwarf2.h
diff --git a/bfd/aoutx.h b/bfd/aoutx.h
index f1aae0e8684..4ed28d9746e 100644
--- a/bfd/aoutx.h
+++ b/bfd/aoutx.h
@@ -4341,6 +4341,7 @@ aout_link_write_symbols (finfo, input_bfd)
 	      switch (discard)
 		{
 		case discard_none:
+		case discard_sec_merge:
 		  break;
 		case discard_l:
 		  if ((type & N_STAB) == 0
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 213ef842f27..601f351b71d 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -1102,6 +1102,14 @@ typedef struct sec
      references found to any symbol in the section.  */
 #define SEC_CLINK 0x10000000
 
+  /* Attempt to merge identical entities in the section.
+     Entity size is given in the entsize field.  */
+#define SEC_MERGE 0x20000000
+
+  /* If given with SEC_MERGE, entities to merge are zero terminated strings
+     where entsize specifies character size instead of fixed size entries.  */
+#define SEC_STRINGS 0x40000000
+
   /*  End of section flags.  */
 
   /* Some internal packed boolean fields.  */
@@ -1214,6 +1222,10 @@ typedef struct sec
 
   unsigned int lineno_count;
 
+  /* Entity size for merging purposes.  */
+
+  unsigned int entsize;
+
   /* Optional information about a COMDAT entry; NULL if not COMDAT.  */
 
   struct bfd_comdat_info *comdat;
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index c6c9e90f216..e1b61a2b7ce 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -241,6 +241,8 @@ struct elf_link_hash_table
   struct elf_link_hash_entry *hgot;
   /* A pointer to information used to link stabs in sections.  */
   PTR stab_info;
+  /* A pointer to information used to merge SEC_MERGE sections.  */
+  PTR merge_info;
   /* A linked list of local symbols to be added to .dynsym.  */
   struct elf_link_local_dynamic_entry *dynlocal;
   /* A linked list of DT_RPATH/DT_RUNPATH names found in dynamic
@@ -712,6 +714,8 @@ struct bfd_elf_section_data
   long dynindx;
   /* A pointer used for .stab linking optimizations.  */
   PTR stab_info;
+  /* A pointer used for SEC_MERGE optimizations.  */
+  PTR merge_info;
   /* A pointer available for the processor specific ELF backend.  */
   PTR tdata;
   /* Nonzero if this section uses RELA relocations, rather than REL.  */
diff --git a/bfd/elf.c b/bfd/elf.c
index 915ddb27146..92a546d3c55 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -386,6 +386,13 @@ _bfd_elf_make_section_from_shdr (abfd, hdr, name)
     flags |= SEC_CODE;
   else if ((flags & SEC_LOAD) != 0)
     flags |= SEC_DATA;
+  if ((hdr->sh_flags & SHF_MERGE) != 0)
+    {
+      flags |= SEC_MERGE;
+      newsect->entsize = hdr->sh_entsize;
+      if ((hdr->sh_flags & SHF_STRINGS) != 0)
+	flags |= SEC_STRINGS;
+    }
 
   /* The debugging sections appear to be recognized only by name, not
      any sort of flag.  */
@@ -1031,6 +1038,7 @@ _bfd_elf_link_hash_table_init (table, abfd, newfunc)
   table->runpath = NULL;
   table->hgot = NULL;
   table->stab_info = NULL;
+  table->merge_info = NULL;
   table->dynlocal = NULL;
   return _bfd_link_hash_table_init (&table->root, abfd, newfunc);
 }
@@ -1809,6 +1817,13 @@ elf_fake_sections (abfd, asect, failedptrarg)
     this_hdr->sh_flags |= SHF_WRITE;
   if ((asect->flags & SEC_CODE) != 0)
     this_hdr->sh_flags |= SHF_EXECINSTR;
+  if ((asect->flags & SEC_MERGE) != 0)
+    {
+      this_hdr->sh_flags |= SHF_MERGE;
+      this_hdr->sh_entsize = asect->entsize;
+      if ((asect->flags & SEC_STRINGS) != 0)
+	this_hdr->sh_flags |= SHF_STRINGS;
+    }
 
   /* Check for processor-specific section types.  */
   if (bed->elf_backend_fake_sections)
diff --git a/bfd/elflink.h b/bfd/elflink.h
index 554713ba9f3..d175223ffa9 100644
--- a/bfd/elflink.h
+++ b/bfd/elflink.h
@@ -2167,6 +2167,18 @@ elf_link_add_object_symbols (abfd, info)
 	}
     }
 
+  if (! info->relocateable && ! dynamic)
+    {
+      asection *s;
+
+      for (s = abfd->sections; s != NULL; s = s->next)
+	if ((s->flags & SEC_MERGE)
+	    && ! _bfd_merge_section (abfd,
+				     &elf_hash_table (info)->merge_info,
+				     s, &elf_section_data (s)->merge_info))
+	  goto error_return;
+    }
+
   return true;
 
  error_return:
@@ -4069,6 +4081,8 @@ static boolean elf_link_flush_output_syms
   PARAMS ((struct elf_final_link_info *));
 static boolean elf_link_output_extsym
   PARAMS ((struct elf_link_hash_entry *, PTR));
+static boolean elf_link_sec_merge_syms
+  PARAMS ((struct elf_link_hash_entry *, PTR));
 static boolean elf_link_input_bfd
   PARAMS ((struct elf_final_link_info *, bfd *));
 static boolean elf_reloc_link_order
@@ -4218,6 +4232,7 @@ elf_bfd_final_link (abfd, info)
   Elf_Internal_Shdr *symstrtab_hdr;
   struct elf_backend_data *bed = get_elf_backend_data (abfd);
   struct elf_outext_info eoinfo;
+  boolean merged;
 
   if (info->shared)
     abfd->flags |= DYNAMIC;
@@ -4263,6 +4278,7 @@ elf_bfd_final_link (abfd, info)
   max_external_reloc_size = 0;
   max_internal_reloc_count = 0;
   max_sym_count = 0;
+  merged = false;
   for (o = abfd->sections; o != (asection *) NULL; o = o->next)
     {
       o->reloc_count = 0;
@@ -4284,6 +4300,9 @@ elf_bfd_final_link (abfd, info)
 		 the linker has decided to not include.  */
 	      sec->linker_mark = true;
 
+	      if (sec->flags & SEC_MERGE)
+		merged = true;
+
 	      if (info->relocateable || info->emitrelocations)
 		o->reloc_count += sec->reloc_count;
 
@@ -4341,6 +4360,10 @@ elf_bfd_final_link (abfd, info)
 	o->vma = 0;
     }
 
+  if (! info->relocateable && merged)
+    elf_link_hash_traverse (elf_hash_table (info),
+			    elf_link_sec_merge_syms, (PTR) abfd);
+
   /* 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.  */
@@ -5060,6 +5083,33 @@ elf_link_flush_output_syms (finfo)
   return true;
 }
 
+/* Adjust all external symbols pointing into SEC_MERGE sections
+   to reflect the object merging within the sections.  */
+
+static boolean
+elf_link_sec_merge_syms (h, data)
+     struct elf_link_hash_entry *h;
+     PTR data;
+{
+  asection *sec;
+
+  if ((h->root.type == bfd_link_hash_defined
+       || h->root.type == bfd_link_hash_defweak)
+      && ((sec = h->root.u.def.section)->flags & SEC_MERGE)
+      && elf_section_data (sec)->merge_info)
+    {
+      bfd *output_bfd = (bfd *) data;
+
+      h->root.u.def.value =
+	_bfd_merged_section_offset (output_bfd,
+				    &h->root.u.def.section,
+				    elf_section_data (sec)->merge_info,
+				    h->root.u.def.value, (bfd_vma) 0);
+    }
+
+  return true;
+}
+
 /* 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
@@ -5525,7 +5575,15 @@ elf_link_input_bfd (finfo, input_bfd)
 	  name = isec->name;
 	}
       else if (isym->st_shndx > 0 && isym->st_shndx < SHN_LORESERVE)
-	isec = section_from_elf_index (input_bfd, isym->st_shndx);
+	{
+	  isec = section_from_elf_index (input_bfd, isym->st_shndx);
+	  if (isec && elf_section_data (isec)->merge_info
+	      && ELF_ST_TYPE (isym->st_info) != STT_SECTION)
+	    isym->st_value =
+	      _bfd_merged_section_offset (output_bfd, &isec,
+					  elf_section_data (isec)->merge_info,
+					  isym->st_value, (bfd_vma) 0);
+	}
       else if (isym->st_shndx == SHN_ABS)
 	{
 	  isec = bfd_abs_section_ptr;
@@ -5627,7 +5685,9 @@ elf_link_input_bfd (finfo, input_bfd)
       if ((finfo->info->strip == strip_some
 	   && (bfd_hash_lookup (finfo->info->keep_hash, name, false, false)
 	       == NULL))
-	  || (finfo->info->discard == discard_l
+	  || (((finfo->info->discard == discard_sec_merge
+		&& (isec->flags & SEC_MERGE) && ! finfo->info->relocateable)
+	       || finfo->info->discard == discard_l)
 	      && bfd_is_local_label_name (input_bfd, name)))
 	continue;
 
@@ -5889,7 +5949,20 @@ elf_link_input_bfd (finfo, input_bfd)
 	}
 
       /* Write out the modified section contents.  */
-      if (elf_section_data (o)->stab_info == NULL)
+      if (elf_section_data (o)->stab_info)
+	{
+	  if (! (_bfd_write_section_stabs
+		 (output_bfd, &elf_hash_table (finfo->info)->stab_info,
+		  o, &elf_section_data (o)->stab_info, contents)))
+	    return false;
+	}
+      else if (elf_section_data (o)->merge_info)
+	{
+	  if (! (_bfd_write_merged_section
+		 (output_bfd, o, elf_section_data (o)->merge_info)))
+	    return false;
+	}
+      else
 	{
 	  if (! (o->flags & SEC_EXCLUDE) &&
 	      ! bfd_set_section_contents (output_bfd, o->output_section,
@@ -5899,13 +5972,6 @@ elf_link_input_bfd (finfo, input_bfd)
 					   : o->_raw_size)))
 	    return false;
 	}
-      else
-	{
-	  if (! (_bfd_write_section_stabs
-		 (output_bfd, &elf_hash_table (finfo->info)->stab_info,
-		  o, &elf_section_data (o)->stab_info, contents)))
-	    return false;
-	}
     }
 
   return true;
diff --git a/bfd/libbfd-in.h b/bfd/libbfd-in.h
index dc2cd1128a0..dae76354139 100644
--- a/bfd/libbfd-in.h
+++ b/bfd/libbfd-in.h
@@ -462,6 +462,21 @@ extern boolean _bfd_write_stab_strings PARAMS ((bfd *, PTR *));
 extern bfd_vma _bfd_stab_section_offset
   PARAMS ((bfd *, PTR *, asection *, PTR *, bfd_vma));
 
+/* Attempt to merge a SEC_MERGE section.  */
+
+extern boolean _bfd_merge_section
+  PARAMS ((bfd *, PTR *, asection *, PTR *));
+
+/* Write out a merged section.  */
+
+extern boolean _bfd_write_merged_section
+  PARAMS ((bfd *, asection *, PTR));
+
+/* Find an offset within a modified SEC_MERGE section.  */
+
+extern bfd_vma _bfd_merged_section_offset
+  PARAMS ((bfd *, asection **, PTR, bfd_vma, bfd_vma));
+
 /* Create a string table.  */
 extern struct bfd_strtab_hash *_bfd_stringtab_init PARAMS ((void));
 
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index 1a8268d19f8..56e659165cd 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -462,6 +462,21 @@ extern boolean _bfd_write_stab_strings PARAMS ((bfd *, PTR *));
 extern bfd_vma _bfd_stab_section_offset
   PARAMS ((bfd *, PTR *, asection *, PTR *, bfd_vma));
 
+/* Attempt to merge a SEC_MERGE section.  */
+
+extern boolean _bfd_merge_section
+  PARAMS ((bfd *, PTR *, asection *, PTR *));
+
+/* Write out a merged section.  */
+
+extern boolean _bfd_write_merged_section
+  PARAMS ((bfd *, asection *, PTR));
+
+/* Find an offset within a modified SEC_MERGE section.  */
+
+extern bfd_vma _bfd_merged_section_offset
+  PARAMS ((bfd *, asection **, PTR, bfd_vma, bfd_vma));
+
 /* Create a string table.  */
 extern struct bfd_strtab_hash *_bfd_stringtab_init PARAMS ((void));
 
diff --git a/bfd/linker.c b/bfd/linker.c
index fcfeb83412d..3efaf665d7f 100644
--- a/bfd/linker.c
+++ b/bfd/linker.c
@@ -2279,6 +2279,12 @@ _bfd_generic_link_output_symbols (output_bfd, input_bfd, info, psymalloc)
 		case discard_all:
 		  output = false;
 		  break;
+		case discard_sec_merge:
+		  output = true;
+		  if (info->relocateable
+		      || ! (sym->section->flags & SEC_MERGE))
+		    break;
+		  /* FALLTHROUGH */
 		case discard_l:
 		  if (bfd_is_local_label (input_bfd, sym))
 		    output = false;
diff --git a/bfd/merge.c b/bfd/merge.c
new file mode 100644
index 00000000000..ace069eca0d
--- /dev/null
+++ b/bfd/merge.c
@@ -0,0 +1,606 @@
+/* SEC_MERGE support.
+   Copyright 2001 Free Software Foundation, Inc.
+   Written by Jakub Jelinek <jakub@redhat.com>.
+
+This file is part of BFD, the Binary File Descriptor library.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+/* This file contains support for merging duplicate entities within sections,
+   as used in ELF SHF_MERGE.  */
+
+#include "bfd.h"
+#include "sysdep.h"
+#include "libbfd.h"
+
+#include <ctype.h>
+
+/* An entry in the section merge hash table.  */
+
+struct sec_merge_hash_entry
+{
+  struct bfd_hash_entry root;
+  /* Length of this entry.  */
+  unsigned int len;
+  /* Index within the merged section.  */
+  bfd_size_type index;
+  /* Which section is it in.  */
+  asection *sec;
+  /* Next entity in the hash table.  */
+  struct sec_merge_hash_entry *next;
+};
+
+/* The section merge hash table.  */
+
+struct sec_merge_hash
+{
+  struct bfd_hash_table table;
+  /* Next available index.  */
+  bfd_size_type size;
+  /* First entity in the SEC_MERGE sections of this type.  */
+  struct sec_merge_hash_entry *first;
+  /* Last entity in the SEC_MERGE sections of this type.  */
+  struct sec_merge_hash_entry *last;
+  /* Entity size.  */
+  unsigned int entsize;
+  /* Start of each string needs to be aligned to 1 << alignment_power
+     octets.  */
+  unsigned int alignment_power;
+  /* Are entries fixed size or zero terminated strings?  */
+  boolean strings;
+};
+
+struct sec_merge_info
+{
+  /* Chain of sec_merge_infos.  */
+  struct sec_merge_info *next;
+  /* A hash table used to hold section content.  */
+  struct sec_merge_hash *htab;
+  /* The last section attempted for merge.  */
+  asection *last;
+};
+
+struct sec_merge_sec_info
+{
+  /* A hash table used to hold section content.  */
+  struct sec_merge_hash *htab;
+  /* First string in this section.  */
+  struct sec_merge_hash_entry *first;
+  /* Original section content.  */
+  unsigned char contents[1];
+};
+
+static struct bfd_hash_entry *sec_merge_hash_newfunc
+  PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
+static struct sec_merge_hash_entry *sec_merge_hash_lookup
+  PARAMS ((struct sec_merge_hash *, const char *, boolean));
+static struct sec_merge_hash *sec_merge_init
+  PARAMS ((unsigned int, unsigned int, boolean));
+static struct sec_merge_hash_entry *sec_merge_add
+  PARAMS ((struct sec_merge_hash *, const char *));
+static boolean sec_merge_emit
+  PARAMS ((bfd *, struct sec_merge_hash *, struct sec_merge_hash_entry *));
+
+/* Routine to create an entry in a section merge hashtab.  */
+
+static struct bfd_hash_entry *
+sec_merge_hash_newfunc (entry, table, string)
+     struct bfd_hash_entry *entry;
+     struct bfd_hash_table *table;
+     const char *string;
+{
+  struct sec_merge_hash_entry *ret = (struct sec_merge_hash_entry *) entry;
+
+  /* Allocate the structure if it has not already been allocated by a
+     subclass.  */
+  if (ret == (struct sec_merge_hash_entry *) NULL)
+    ret = ((struct sec_merge_hash_entry *)
+	   bfd_hash_allocate (table, sizeof (struct sec_merge_hash_entry)));
+  if (ret == (struct sec_merge_hash_entry *) NULL)
+    return NULL;
+
+  /* Call the allocation method of the superclass.  */
+  ret = ((struct sec_merge_hash_entry *)
+	 bfd_hash_newfunc ((struct bfd_hash_entry *) ret, table, string));
+
+  if (ret)
+    {
+      /* Initialize the local fields.  */
+      ret->index = (bfd_size_type) -1;
+      ret->sec = NULL;
+      ret->next = NULL;
+    }
+
+  return (struct bfd_hash_entry *)ret;
+}
+
+/* Look up an entry in a section merge hash table.  */
+
+static struct sec_merge_hash_entry *
+sec_merge_hash_lookup (table, string, create)
+     struct sec_merge_hash *table;
+     const char *string;
+     boolean create;
+{
+  register const unsigned char *s;
+  register unsigned long hash;
+  register unsigned int c;
+  struct sec_merge_hash_entry *hashp;
+  unsigned int len, i;
+  unsigned int index;
+
+  hash = 0;
+  len = 0;
+  s = (const unsigned char *) string;
+  if (table->strings)
+    {
+      if (table->entsize == 1)
+	{
+	  while ((c = *s++) != '\0')
+	    {
+	      hash += c + (c << 17);
+	      hash ^= hash >> 2;
+	      ++len;
+	    }
+	  hash += len + (len << 17);
+	}
+      else
+	{
+	  for (;;)
+	    {
+	      for (i = 0; i < table->entsize; ++i)
+		if (s[i] != '\0')
+		  break;
+	      if (i == table->entsize)
+		break;
+	      for (i = 0; i < table->entsize; ++i)
+		{
+		  c = *s++;
+		  hash += c + (c << 17);
+		  hash ^= hash >> 2;
+		}
+	      ++len;
+	    }
+	  hash += len + (len << 17);
+	  len *= table->entsize;
+	}
+      hash ^= hash >> 2;
+      len += table->entsize;
+    }      
+  else
+    {
+      for (i = 0; i < table->entsize; ++i)
+	{
+	  c = *s++;
+	  hash += c + (c << 17);
+	  hash ^= hash >> 2;
+	}
+      len = table->entsize;
+    }
+
+  index = hash % table->table.size;
+  for (hashp = (struct sec_merge_hash_entry *) table->table.table[index];
+       hashp != (struct sec_merge_hash_entry *) NULL;
+       hashp = (struct sec_merge_hash_entry *) hashp->next)
+    {
+      if (hashp->root.hash == hash
+	  && len == hashp->len
+	  && memcmp (hashp->root.string, string, len) == 0)
+	return hashp;
+    }
+
+  if (! create)
+    return (struct sec_merge_hash_entry *) NULL;
+
+  hashp = (struct sec_merge_hash_entry *)
+	  sec_merge_hash_newfunc ((struct bfd_hash_entry *) NULL,
+				  (struct bfd_hash_table *) table, string);
+  if (hashp == (struct sec_merge_hash_entry *) NULL)
+    return (struct sec_merge_hash_entry *) NULL;
+  hashp->root.string = string;
+  hashp->root.hash = hash;
+  hashp->len = len;
+  hashp->root.next = table->table.table[index];
+  table->table.table[index] = (struct bfd_hash_entry *) hashp;
+
+  return hashp;
+}
+
+/* Create a new hash table.  */
+
+static struct sec_merge_hash *
+sec_merge_init (alignment_power, entsize, strings)
+     unsigned int alignment_power, entsize;
+     boolean strings;
+{
+  struct sec_merge_hash *table;
+
+  table = ((struct sec_merge_hash *)
+	   bfd_malloc (sizeof (struct sec_merge_hash)));
+  if (table == NULL)
+    return NULL;
+
+  if (! bfd_hash_table_init (&table->table, sec_merge_hash_newfunc))
+    {
+      free (table);
+      return NULL;
+    }
+
+  table->size = 0;
+  table->first = NULL;
+  table->last = NULL;
+  table->alignment_power = alignment_power;
+  table->entsize = entsize;
+  table->strings = strings;
+
+  return table;
+}
+
+/* Get the index of an entity in a hash table, adding it if it is not
+   already present.  */
+
+static struct sec_merge_hash_entry *
+sec_merge_add (tab, str)
+     struct sec_merge_hash *tab;
+     const char *str;
+{
+  register struct sec_merge_hash_entry *entry;
+
+  entry = sec_merge_hash_lookup (tab, str, true);
+  if (entry == NULL)
+    return NULL;
+
+  if (entry->index == (bfd_size_type) -1)
+    {
+      entry->index = tab->size;
+      tab->size += entry->len;
+      tab->size = align_power (tab->size, tab->alignment_power);
+      if (tab->first == NULL)
+	tab->first = entry;
+      else
+	tab->last->next = entry;
+      tab->last = entry;
+    }
+
+  return entry;
+}
+
+static boolean
+sec_merge_emit (abfd, tab, entry)
+     register bfd *abfd;
+     struct sec_merge_hash *tab;
+     struct sec_merge_hash_entry *entry;
+{
+  asection *sec = entry->sec;
+  char *pad = "";
+
+  if (tab->alignment_power)
+    pad = bfd_zmalloc (1 << tab->alignment_power);
+
+  for (; entry != NULL && entry->sec == sec; entry = entry->next)
+    {
+      register const char *str;
+      register size_t len;
+
+      str = entry->root.string;
+      len = entry->len;
+
+      if (bfd_write ((PTR) str, 1, len, abfd) != len)
+	break;
+
+      if (tab->alignment_power)
+	{
+	  len &= (1 << tab->alignment_power) - 1;
+	  if (len && bfd_write ((PTR) pad, 1,
+				(1 << tab->alignment_power) - len,
+				abfd) != (1 << tab->alignment_power) - len)
+	    break;
+	}
+    }
+
+  if (tab->alignment_power)
+    free (pad);
+
+  return entry == NULL || entry->sec != sec;
+}
+
+/* This function is called for each input file from the add_symbols
+   pass of the linker.  */
+
+boolean
+_bfd_merge_section (abfd, psinfo, sec, psecinfo)
+     bfd *abfd;
+     PTR *psinfo;
+     asection *sec;
+     PTR *psecinfo;
+{
+  boolean first, nul;
+  struct sec_merge_info *sinfo;
+  struct sec_merge_sec_info *secinfo;
+  unsigned char *p, *end;
+  bfd_vma mask;
+  unsigned int align;
+  unsigned int i;
+
+  if (sec->_raw_size == 0
+      || (sec->flags & SEC_MERGE) == 0
+      || sec->entsize == 0)
+    return true;
+
+  if ((sec->flags & SEC_RELOC) != 0)
+    {
+      /* We aren't prepared to handle relocations in merged sections.  */
+      return true;
+    }
+
+  if (sec->output_section != NULL
+      && bfd_is_abs_section (sec->output_section))
+    {
+      /* The section is being discarded from the link, so we should
+	 just ignore it.  */
+      return true;
+    }
+
+  align = bfd_get_section_alignment (abfd, sec);
+  if ((sec->flags & SEC_STRINGS)
+      && ((sec->entsize < (unsigned int)(1 << align)
+	   && (sec->entsize & (sec->entsize - 1)))
+	  || (sec->entsize > (unsigned int)(1 << align)
+	      && (sec->entsize & ((1 << align) - 1)))))
+    {
+      /* Sanity check.  If string character size is smaller than
+	 alignment, then we require character size to be a power
+	 of 2, otherwise character size must be integer multiple
+	 of alignment.  */
+      return true;
+    }
+
+  first = false;
+
+  for (sinfo = (struct sec_merge_info *) *psinfo; sinfo; sinfo = sinfo->next)
+    if (! ((sinfo->last->flags ^ sec->flags) & (SEC_MERGE | SEC_STRINGS))
+	&& sinfo->last->entsize == sec->entsize
+	&& ! strcmp (sinfo->last->name, sec->name)
+	&& bfd_get_section_alignment (abfd, sinfo->last) == align)
+      break;
+
+  if (sinfo == NULL)
+    {
+      /* Initialize the information we need to keep track of.  */
+      first = true;
+      sinfo = (struct sec_merge_info *)
+	      bfd_alloc (abfd, sizeof (struct sec_merge_info));
+      if (sinfo == NULL)
+	goto error_return;
+      sinfo->next = (struct sec_merge_info *) *psinfo;
+      *psinfo = (PTR) sinfo;
+      sinfo->htab =
+	sec_merge_init ((sec->flags & SEC_STRINGS) ? align : 0,
+			sec->entsize, (sec->flags & SEC_STRINGS));
+      if (sinfo->htab == NULL)
+	goto error_return;
+    }
+
+  /* Read the section from abfd.  */
+
+  *psecinfo = bfd_alloc (abfd, sizeof (struct sec_merge_sec_info)
+			       + sec->_raw_size - 1);
+  if (*psecinfo == NULL)
+    goto error_return;
+
+  secinfo = (struct sec_merge_sec_info *)*psecinfo;
+  secinfo->htab = sinfo->htab;
+  sinfo->htab->size = 0;
+  secinfo->first = NULL;
+
+  if (! bfd_get_section_contents (abfd, sec, secinfo->contents, 0,
+				  sec->_raw_size))
+    goto error_return;
+
+  end = secinfo->contents + sec->_raw_size;
+  nul = false;
+  mask = ((bfd_vma)1 << sinfo->htab->alignment_power) - 1;
+  if (sec->flags & SEC_STRINGS)
+    {
+      for (p = secinfo->contents; p < end;)
+	{
+	  struct sec_merge_hash_entry *entry;
+
+	  entry = sec_merge_add (sinfo->htab, p);
+	  if (entry->sec == NULL)
+	    {
+	      if (secinfo->first == NULL)
+		secinfo->first = entry;
+	      entry->sec = sec;
+	    }
+	  p += entry->len;
+	  if (sec->entsize == 1)
+	    {
+	      while (p < end && *p == 0)
+		{
+		  if (!nul && !((p - secinfo->contents) & mask))
+		    {
+		      nul = true;
+		      entry = sec_merge_add (sinfo->htab, "");
+		      if (entry->sec == NULL)
+		        {
+			  if (secinfo->first == NULL)
+			    secinfo->first = entry;
+			  entry->sec = sec;
+		        }
+		    }
+		  p++;
+	        }
+	    }
+	  else
+	    {
+	      while (p < end)
+		{
+		  for (i = 0; i < sec->entsize; i++)
+		    if (p[i] != '\0')
+		      break;
+		  if (i != sec->entsize)
+		    break;
+		  if (!nul && !((p - secinfo->contents) & mask))
+		    {
+		      nul = true;
+		      entry = sec_merge_add (sinfo->htab, p);
+		      if (entry->sec == NULL)
+			{
+			  if (secinfo->first == NULL)
+			    secinfo->first = entry;
+			  entry->sec = sec;
+			}
+		    }
+		  p += sec->entsize;
+		}
+	    }
+	}
+    }
+  else
+    {
+      for (p = secinfo->contents; p < end; p += sec->entsize)
+	{
+	  struct sec_merge_hash_entry *entry;
+
+	  entry = sec_merge_add (sinfo->htab, p);
+	  if (entry->sec == NULL)
+	    {
+	      if (secinfo->first == NULL)
+		secinfo->first = entry;
+	      entry->sec = sec;
+	    }
+	}
+    }
+
+  sec->_cooked_size = sinfo->htab->size;
+  if (!sec->_cooked_size)
+    sec->flags |= SEC_EXCLUDE;
+  sinfo->last = sec;
+  return true;
+
+ error_return:
+  if (*psecinfo != NULL)
+    free (*psecinfo);
+  *psecinfo = NULL;
+  return false;
+}
+
+/* Write out the merged section.  */
+
+boolean
+_bfd_write_merged_section (output_bfd, sec, psecinfo)
+     bfd *output_bfd;
+     asection *sec;
+     PTR psecinfo;
+{
+  struct sec_merge_sec_info *secinfo;
+
+  secinfo = (struct sec_merge_sec_info *) psecinfo;
+
+  if (!secinfo->first)
+    return true;
+
+  if (bfd_seek (output_bfd,
+		(sec->output_section->filepos + sec->output_offset),
+		SEEK_SET) != 0)
+    return false;
+
+  if (! sec_merge_emit (output_bfd, secinfo->htab, secinfo->first))
+    return false;
+
+  return true;
+}
+
+/* Adjust an address in the SEC_MERGE section.  Given OFFSET within
+   *PSEC, this returns the new offset in the adjusted SEC_MERGE
+   section and writes the new section back into *PSEC.  */
+
+bfd_vma
+_bfd_merged_section_offset (output_bfd, psec, psecinfo, offset, addend)
+     bfd *output_bfd ATTRIBUTE_UNUSED;
+     asection **psec;
+     PTR psecinfo;
+     bfd_vma offset, addend;
+{
+  struct sec_merge_sec_info *secinfo;
+  struct sec_merge_hash_entry *entry;
+  unsigned char *p;
+  asection *sec = *psec;
+
+  secinfo = (struct sec_merge_sec_info *) psecinfo;
+
+  if (offset + addend >= sec->_raw_size)
+    {
+      if (offset + addend > sec->_raw_size)
+	(*_bfd_error_handler) (_("%s: access beyond end of merged section (%ld + %ld)"),
+			       bfd_get_filename (sec->owner), (long)offset,
+			       (long) addend);
+      return (secinfo->first ? sec->_cooked_size : 0);
+    }
+
+  if (secinfo->htab->strings)
+    {
+      if (sec->entsize == 1)
+	{
+	  p = secinfo->contents + offset + addend - 1;
+	  while (*p && p >= secinfo->contents)
+	    --p;
+	  ++p;
+	}
+      else
+	{
+	  p = secinfo->contents
+	      + ((offset + addend) / sec->entsize) * sec->entsize;
+	  p -= sec->entsize;
+	  while (p >= secinfo->contents)
+	    {
+	      unsigned int i;
+
+	      for (i = 0; i < sec->entsize; ++i)
+		if (p[i] != '\0')
+		  break;
+	      if (i == sec->entsize)
+		break;
+	      p -= sec->entsize;
+	    }
+	  p += sec->entsize;
+	}
+    }
+  else
+    {
+      p = secinfo->contents
+	  + ((offset + addend) / sec->entsize) * sec->entsize;
+    }
+  entry = sec_merge_hash_lookup (secinfo->htab, p, false);
+  if (!entry)
+    {
+      if (! secinfo->htab->strings)
+	abort ();
+      /* This should only happen if somebody points into the padding
+	 after a NUL character but before next entity.  */
+      if (*p)
+	abort ();
+      if (! secinfo->htab->first)
+	abort ();
+      entry = secinfo->htab->first;
+      p = secinfo->contents
+	  + ((offset + addend) / sec->entsize + 1) * sec->entsize
+	  - entry->len;
+    }
+
+  *psec = entry->sec;
+  return entry->index + (secinfo->contents + offset - p);
+}
diff --git a/bfd/pdp11.c b/bfd/pdp11.c
index af5669887ea..c7e9c3cea8c 100644
--- a/bfd/pdp11.c
+++ b/bfd/pdp11.c
@@ -4110,6 +4110,7 @@ aout_link_write_symbols (finfo, input_bfd)
 	      switch (discard)
 		{
 		case discard_none:
+		case discard_sec_merge:
 		  break;
 		case discard_l:
 		  if ((type & N_STAB) == 0