Add SHF_COMPRESSED support to gas and objcopy

This patch adds --compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}
options to gas and objcopy for ELF files. They control how DWARF debug
sections are compressed.  --compress-debug-sections=none is equivalent to
--nocompress-debug-sections.  --compress-debug-sections=zlib and
--compress-debug-sections=zlib-gnu are equivalent to
--compress-debug-sections.  --compress-debug-sections=zlib-gabi compresses
DWARF debug sections with SHF_COMPRESSED from the ELF ABI.  No linker
changes are required to support SHF_COMPRESSED.

bfd/

	* archive.c (_bfd_get_elt_at_filepos): Also copy BFD_COMPRESS_GABI
	bit.
	* bfd.c (bfd::flags): Increase size to 18 bits.
	(BFD_COMPRESS_GABI): New.
	(BFD_FLAGS_SAVED): Add BFD_COMPRESS_GABI.
	(BFD_FLAGS_FOR_BFD_USE_MASK): Likewise.
	(bfd_update_compression_header): New fuction.
	(bfd_check_compression_header): Likewise.
	(bfd_get_compression_header_size): Likewise.
	(bfd_is_section_compressed_with_header): Likewise.
	* compress.c (MAX_COMPRESSION_HEADER_SIZE): New.
	(bfd_compress_section_contents): Return the uncompressed size if
	the full section contents is compressed successfully.  Support
	converting from/to .zdebug* sections.
	(bfd_get_full_section_contents): Call
	bfd_get_compression_header_size to get compression header size.
	(bfd_is_section_compressed): Renamed to ...
	(bfd_is_section_compressed_with_header): This.  Add a pointer
	argument to return compression header size.
	(bfd_is_section_compressed): Use it.
	(bfd_init_section_decompress_status): Call
	bfd_get_compression_header_size to get compression header size.
	Return FALSE if uncompressed section size is 0.
	* elf.c (_bfd_elf_make_section_from_shdr): Support converting
	from/to .zdebug* sections.
	* bfd-in2.h: Regenerated.

binutils/

	* objcopy.c (do_debug_sections): Add compress_zlib,
	compress_gnu_zlib and compress_gabi_zlib.
	(copy_options): Use optional_argument on compress-debug-sections.
	(copy_usage): Update --compress-debug-sections.
	(copy_file): Handle compress_zlib, compress_gnu_zlib and
	compress_gabi_zlib.
	(copy_main): Handle
	--compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}.
	* doc/binutils.texi: Document
	--compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}.

binutils/testsuite/

	* compress.exp: Add tests for
	--compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}.
	* binutils-all/dw2-3.rS: New file.
	* binutils-all/dw2-3.rt: Likewise.
	* binutils-all/libdw2-compressedgabi.out: Likewise.

gas/

	* as.c (show_usage): Update --compress-debug-sections.
	(std_longopts): Use optional_argument on compress-debug-sections.
	(parse_args): Handle
	--compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}.
	* as.h (compressed_debug_section_type): New.
	(flag_compress_debug): Change type to compressed_debug_section_type.
	--compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}.
	* write.c (compress_debug): Set BFD_COMPRESS_GABI for
	--compress-debug-sections=zlib-gabi.  Call
	bfd_get_compression_header_size to get compression header size.
	Don't rename section name for --compress-debug-sections=zlib-gabi.
	* config/tc-i386.c (compressed_debug_section_type): Set to
	COMPRESS_DEBUG_ZLIB.
	* doc/as.texinfo: Document
	--compress-debug-sections={none|zlib|zlib-gnu|zlib-gabi}.

gas/testsuite/

	* gas/i386/dw2-compressed-1.d: New file.
	* gas/i386/dw2-compressed-2.d: Likewise.
	* gas/i386/dw2-compressed-3.d: Likewise.
	* gas/i386/x86-64-dw2-compressed-2.d: Likewise.
	* gas/i386/i386.exp: Run dw2-compressed-2, dw2-compressed-1,
	dw2-compressed-3 and x86-64-dw2-compressed-2.

ld/testsuite/

	* ld-elf/compress.exp: Add a test for
	--compress-debug-sections=zlib-gabi.
	(build_tests): Add 2 tests for --compress-debug-sections=zlib-gabi.
	(run_tests): Likewise.
	Verify linker output with zlib-gabi compressed debug input.
	* ld-elf/compressed1a.d: New file.
	* ld-elf/compressed1b.d: Likewise.
	* ld-elf/compressed1c.d: Likewise.

1 files changed, 30 insertions, 13 deletions

diff --git a/gas/write.c b/gas/write.c
index 1ae47a9..bc76962 100644
--- a/gas/write.c
+++ b/gas/write.c
@@ -1413,6 +1413,9 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
   struct z_stream_s *strm;
   int x;
   flagword flags = bfd_get_section_flags (abfd, sec);
+  unsigned int header_size, compression_header_size;
+  /* Maximimum compression header is 24 bytes.  */
+  bfd_byte compression_header[24];
 
   if (seginfo == NULL
       || sec->size < 32
@@ -1427,18 +1430,26 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
   if (strm == NULL)
     return;
 
+  if (flag_compress_debug == COMPRESS_DEBUG_GABI_ZLIB)
+    stdoutput->flags |= BFD_COMPRESS | BFD_COMPRESS_GABI;
+  else
+    stdoutput->flags |= BFD_COMPRESS;
+  compression_header_size
+    = bfd_get_compression_header_size (stdoutput, NULL);
+
   /* Create a new frag to contain the "ZLIB" header.  */
+  header_size = 12 + compression_header_size;
   first_newf = frag_alloc (ob);
-  if (obstack_room (ob) < 12)
+  if (obstack_room (ob) < header_size)
     first_newf = frag_alloc (ob);
-  if (obstack_room (ob) < 12)
-    as_fatal (_("can't extend frag %u chars"), 12);
+  if (obstack_room (ob) < header_size)
+    as_fatal (_("can't extend frag %u chars"), header_size);
   last_newf = first_newf;
-  obstack_blank_fast (ob, 12);
+  obstack_blank_fast (ob, header_size);
   last_newf->fr_type = rs_fill;
-  last_newf->fr_fix = 12;
+  last_newf->fr_fix = header_size;
   header = last_newf->fr_literal;
-  compressed_size = 12;
+  compressed_size = header_size;
 
   /* Stream the frags through the compression engine, adding new frags
      as necessary to accomodate the compressed output.  */
@@ -1522,21 +1533,27 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
   if (compressed_size >= uncompressed_size)
     return;
 
-  memcpy (header, "ZLIB", 4);
-  bfd_putb64 (uncompressed_size, header + 4);
+  if (compression_header_size)
+    memcpy (header, compression_header, compression_header_size);
+  memcpy (header + compression_header_size, "ZLIB", 4);
+  bfd_putb64 (uncompressed_size, header + compression_header_size + 4);
 
   /* Replace the uncompressed frag list with the compressed frag list.  */
   seginfo->frchainP->frch_root = first_newf;
   seginfo->frchainP->frch_last = last_newf;
 
   /* Update the section size and its name.  */
+  bfd_update_compression_header (abfd, (bfd_byte *) header, sec);
   x = bfd_set_section_size (abfd, sec, compressed_size);
   gas_assert (x);
-  compressed_name = (char *) xmalloc (strlen (section_name) + 2);
-  compressed_name[0] = '.';
-  compressed_name[1] = 'z';
-  strcpy (compressed_name + 2, section_name + 1);
-  bfd_section_name (stdoutput, sec) = compressed_name;
+  if (!compression_header_size)
+    {
+      compressed_name = (char *) xmalloc (strlen (section_name) + 2);
+      compressed_name[0] = '.';
+      compressed_name[1] = 'z';
+      strcpy (compressed_name + 2, section_name + 1);
+      bfd_section_name (stdoutput, sec) = compressed_name;
+    }
 }
 
 static void