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.

12 files changed, 338 insertions, 20 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 6f9118da..7ff56c1 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,21 @@
+2015-04-08  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* 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}.
+
 2015-04-07  Renlin Li  <renlin.li@arm.com>
 
 	* config/tc-aarch64.c (mapping_state): Use subseg_text_p.
diff --git a/gas/as.c b/gas/as.c
index a670d3e..2a8923f 100644
--- a/gas/as.c
+++ b/gas/as.c
@@ -246,7 +246,7 @@ Options:\n\
   fprintf (stream, _("\
   --alternate             initially turn on alternate macro syntax\n"));
   fprintf (stream, _("\
-  --compress-debug-sections\n\
+  --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi}]\n\
                           compress DWARF debug sections using zlib\n"));
   fprintf (stream, _("\
   --nocompress-debug-sections\n\
@@ -471,7 +471,7 @@ parse_args (int * pargc, char *** pargv)
     ,{"a", optional_argument, NULL, 'a'}
     /* Handle -al=<FILE>.  */
     ,{"al", optional_argument, NULL, OPTION_AL}
-    ,{"compress-debug-sections", no_argument, NULL, OPTION_COMPRESS_DEBUG}
+    ,{"compress-debug-sections", optional_argument, NULL, OPTION_COMPRESS_DEBUG}
     ,{"nocompress-debug-sections", no_argument, NULL, OPTION_NOCOMPRESS_DEBUG}
     ,{"debug-prefix-map", required_argument, NULL, OPTION_DEBUG_PREFIX_MAP}
     ,{"defsym", required_argument, NULL, OPTION_DEFSYM}
@@ -655,11 +655,31 @@ This program has absolutely no warranty.\n"));
 	  exit (EXIT_SUCCESS);
 
 	case OPTION_COMPRESS_DEBUG:
-	  flag_compress_debug = 1;
+	  if (optarg)
+	    {
+#if defined OBJ_ELF || defined OBJ_MAYBE_ELF
+	      if (strcasecmp (optarg, "none") == 0)
+		flag_compress_debug = COMPRESS_DEBUG_NONE;
+	      else if (strcasecmp (optarg, "zlib") == 0)
+		flag_compress_debug = COMPRESS_DEBUG_ZLIB;
+	      else if (strcasecmp (optarg, "zlib-gnu") == 0)
+		flag_compress_debug = COMPRESS_DEBUG_GNU_ZLIB;
+	      else if (strcasecmp (optarg, "zlib-gabi") == 0)
+		flag_compress_debug = COMPRESS_DEBUG_GABI_ZLIB;
+	      else
+		as_fatal (_("Invalid --compress-debug-sections option: `%s'"),
+			  optarg);
+#else
+	      as_fatal (_("--compress-debug-sections=%s is unsupported"),
+			optarg);
+#endif
+	    }
+	  else
+	    flag_compress_debug = COMPRESS_DEBUG;
 	  break;
 
 	case OPTION_NOCOMPRESS_DEBUG:
-	  flag_compress_debug = 0;
+	  flag_compress_debug = COMPRESS_DEBUG_NONE;
 	  break;
 
 	case OPTION_DEBUG_PREFIX_MAP:
diff --git a/gas/as.h b/gas/as.h
index 2f05745..e04cc0f 100644
--- a/gas/as.h
+++ b/gas/as.h
@@ -370,8 +370,18 @@ COMMON int flag_strip_local_absolute;
 /* True if we should generate a traditional format object file.  */
 COMMON int flag_traditional_format;
 
-/* TRUE if debug sections should be compressed.  */
-COMMON int flag_compress_debug;
+/* Types of compressed debug sections.  We currently support zlib.  */
+enum compressed_debug_section_type
+{
+  COMPRESS_DEBUG_NONE = 0,
+  COMPRESS_DEBUG,
+  COMPRESS_DEBUG_ZLIB,
+  COMPRESS_DEBUG_GNU_ZLIB,
+  COMPRESS_DEBUG_GABI_ZLIB
+};
+
+/* Type of compressed debug sections we should generate.   */
+COMMON enum compressed_debug_section_type flag_compress_debug;
 
 /* TRUE if .note.GNU-stack section with SEC_CODE should be created */
 COMMON int flag_execstack;
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 8266134..1ab1252 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -35,7 +35,8 @@
 
 #ifdef TE_LINUX
 /* Default to compress debug sections for Linux.  */
-int flag_compress_debug = 1;
+enum compressed_debug_section_type flag_compress_debug
+  = COMPRESS_DEBUG_ZLIB;
 #endif
 
 #ifndef REGISTER_WARNINGS
diff --git a/gas/doc/as.texinfo b/gas/doc/as.texinfo
index bedb4d5..95d6c38 100644
--- a/gas/doc/as.texinfo
+++ b/gas/doc/as.texinfo
@@ -630,6 +630,22 @@ to begin with @samp{.zdebug}, and the resulting object file may not be
 compatible with older linkers and object file utilities.  Note if compression
 would make a given section @emph{larger} then it is not compressed or renamed.
 
+@ifset ELF
+@cindex @samp{--compress-debug-sections=} option
+@item --compress-debug-sections=none
+@itemx --compress-debug-sections=zlib
+@itemx --compress-debug-sections=zlib-gnu
+@itemx --compress-debug-sections=zlib-gabi
+These options control how DWARF debug sections are compressed.
+@option{--compress-debug-sections=none} is equivalent to
+@option{--nocompress-debug-sections}.
+@option{--compress-debug-sections=zlib} and
+@option{--compress-debug-sections=zlib-gnu} are equivalent to
+@option{--compress-debug-sections}.
+@option{--compress-debug-sections=zlib-gabi} compresses
+DWARF debug sections with SHF_COMPRESSED from the ELF ABI.
+@end ifset
+
 @item --nocompress-debug-sections
 Do not compress DWARF debug sections.  This is the default.
 
diff --git a/gas/testsuite/ChangeLog b/gas/testsuite/ChangeLog
index c896ec5..fc2b934 100644
--- a/gas/testsuite/ChangeLog
+++ b/gas/testsuite/ChangeLog
@@ -1,3 +1,12 @@
+2015-04-08  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* 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.
+
 2015-04-06  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* lib/gas-defs.exp (run_dump_test): Remove is_zlib_supported check.
diff --git a/gas/testsuite/gas/i386/dw2-compressed-1.d b/gas/testsuite/gas/i386/dw2-compressed-1.d
new file mode 100644
index 0000000..f4c110d
--- /dev/null
+++ b/gas/testsuite/gas/i386/dw2-compressed-1.d
@@ -0,0 +1,105 @@
+#source: dw2-compress-1.s
+#as: --compress-debug-sections=zlib-gabi
+#readelf: -w
+#name: DWARF2 debugging information 1 with SHF_COMPRESSED
+
+Contents of the .debug_info section:
+
+  Compilation Unit @ offset 0x0:
+   Length:        0x4e \(32-bit\)
+   Version:       2
+   Abbrev Offset: 0x0
+   Pointer Size:  4
+ <0><b>: Abbrev Number: 1 \(DW_TAG_compile_unit\)
+    <c>   DW_AT_stmt_list   : 0x0
+    <10>   DW_AT_high_pc     : 0x4
+    <14>   DW_AT_low_pc      : 0x0
+    <18>   DW_AT_name        : file1.txt
+    <22>   DW_AT_producer    : GNU C 3.3.3
+    <2e>   DW_AT_language    : 1	\(ANSI C\)
+ <1><2f>: Abbrev Number: 2 \(DW_TAG_subprogram\)
+    <30>   DW_AT_external    : 1
+    <31>   DW_AT_decl_file   : 1
+    <32>   DW_AT_decl_line   : 2
+    <33>   DW_AT_name        : func_cu1
+    <3c>   DW_AT_type        : <0x4a>
+    <40>   DW_AT_low_pc      : 0x0
+    <44>   DW_AT_high_pc     : 0x4
+    <48>   DW_AT_frame_base  : 1 byte block: 55 	\(DW_OP_reg5 \([^()]*\)\)
+ <1><4a>: Abbrev Number: 3 \(DW_TAG_base_type\)
+    <4b>   DW_AT_name        : int
+    <4f>   DW_AT_byte_size   : 4
+    <50>   DW_AT_encoding    : 5	\(signed\)
+ <1><51>: Abbrev Number: 0
+
+Contents of the .debug_abbrev section:
+
+  Number TAG \(0x0\)
+   1      DW_TAG_compile_unit    \[has children\]
+    DW_AT_stmt_list    DW_FORM_data4
+    DW_AT_high_pc      DW_FORM_addr
+    DW_AT_low_pc       DW_FORM_addr
+    DW_AT_name         DW_FORM_string
+    DW_AT_producer     DW_FORM_string
+    DW_AT_language     DW_FORM_data1
+    DW_AT value: 0     DW_FORM value: 0
+   2      DW_TAG_subprogram    \[no children\]
+    DW_AT_external     DW_FORM_flag
+    DW_AT_decl_file    DW_FORM_data1
+    DW_AT_decl_line    DW_FORM_data1
+    DW_AT_name         DW_FORM_string
+    DW_AT_type         DW_FORM_ref4
+    DW_AT_low_pc       DW_FORM_addr
+    DW_AT_high_pc      DW_FORM_addr
+    DW_AT_frame_base   DW_FORM_block1
+    DW_AT value: 0     DW_FORM value: 0
+   3      DW_TAG_base_type    \[no children\]
+    DW_AT_name         DW_FORM_string
+    DW_AT_byte_size    DW_FORM_data1
+    DW_AT_encoding     DW_FORM_data1
+    DW_AT value: 0     DW_FORM value: 0
+
+Raw dump of debug contents of section .debug_line:
+
+  Offset:                      0x0
+  Length:                      62
+  DWARF Version:               2
+  Prologue Length:             35
+  Minimum Instruction Length:  1
+  Initial value of 'is_stmt':  1
+  Line Base:                   1
+  Line Range:                  1
+  Opcode Base:                 16
+
+ Opcodes:
+  Opcode 1 has 0 args
+  Opcode 2 has 1 args
+  Opcode 3 has 1 args
+  Opcode 4 has 1 args
+  Opcode 5 has 1 args
+  Opcode 6 has 0 args
+  Opcode 7 has 0 args
+  Opcode 8 has 0 args
+  Opcode 9 has 1 args
+  Opcode 10 has 0 args
+  Opcode 11 has 0 args
+  Opcode 12 has 1 args
+  Opcode 13 has 0 args
+  Opcode 14 has 0 args
+  Opcode 15 has 0 args
+
+ The Directory Table is empty.
+
+ The File Name Table \(offset 0x.*\):
+  Entry	Dir	Time	Size	Name
+  1	0	0	0	file1.txt
+
+ Line Number Statements:
+  \[0x.*\]  Extended opcode 2: set Address to 0x0
+  \[0x.*\]  Advance Line by 3 to 4
+  \[0x.*\]  Copy
+  \[0x.*\]  Copy
+  \[0x.*\]  Extended opcode 2: set Address to 0x4
+  \[0x.*\]  Extended opcode 1: End of Sequence
+
+
diff --git a/gas/testsuite/gas/i386/dw2-compressed-2.d b/gas/testsuite/gas/i386/dw2-compressed-2.d
new file mode 100644
index 0000000..c62c02f
--- /dev/null
+++ b/gas/testsuite/gas/i386/dw2-compressed-2.d
@@ -0,0 +1,7 @@
+#source: dw2-compress-2.s
+#as: --compress-debug-sections=zlib-gabi
+#addr2line: 0x0 0x10 -e
+#name: DWARF2 debugging information 2 with SHF_COMPRESSED
+
+./dw2-compress-2.c:12
+./dw2-compress-2.c:5
diff --git a/gas/testsuite/gas/i386/dw2-compressed-3.d b/gas/testsuite/gas/i386/dw2-compressed-3.d
new file mode 100644
index 0000000..bd2818b
--- /dev/null
+++ b/gas/testsuite/gas/i386/dw2-compressed-3.d
@@ -0,0 +1,104 @@
+#source: dw2-compress-3.s
+#as: --compress-debug-sections=zlib-gabi
+#readelf: -w
+#name: DWARF2 debugging information 3 with SHF_COMPRESSED
+
+Contents of the .debug_info section:
+
+  Compilation Unit @ offset 0x0:
+   Length:        0x32 \(32-bit\)
+   Version:       4
+   Abbrev Offset: 0x0
+   Pointer Size:  4
+ <0><b>: Abbrev Number: 1 \(DW_TAG_compile_unit\)
+    <c>   DW_AT_producer    : \(indirect string, offset: 0x2\): GNU C 4.8.3
+    <10>   DW_AT_language    : 1	\(ANSI C\)
+    <11>   DW_AT_name        : \(indirect string, offset: 0xe\): dw2-compress-3.c
+    <15>   DW_AT_comp_dir    : \(indirect string, offset: 0x0\): .
+    <19>   DW_AT_stmt_list   : 0x0
+ <1><1d>: Abbrev Number: 2 \(DW_TAG_variable\)
+    <1e>   DW_AT_name        : foo
+    <22>   DW_AT_decl_file   : 1
+    <23>   DW_AT_decl_line   : 1
+    <24>   DW_AT_type        : <0x2e>
+    <28>   DW_AT_external    : 1
+    <28>   DW_AT_location    : 5 byte block: 3 4 0 0 0 	\(DW_OP_addr: 4\)
+ <1><2e>: Abbrev Number: 3 \(DW_TAG_base_type\)
+    <2f>   DW_AT_byte_size   : 4
+    <30>   DW_AT_encoding    : 5	\(signed\)
+    <31>   DW_AT_name        : int
+ <1><35>: Abbrev Number: 0
+
+Contents of the .debug_abbrev section:
+
+  Number TAG \(0x0\)
+   1      DW_TAG_compile_unit    \[has children\]
+    DW_AT_producer     DW_FORM_strp
+    DW_AT_language     DW_FORM_data1
+    DW_AT_name         DW_FORM_strp
+    DW_AT_comp_dir     DW_FORM_strp
+    DW_AT_stmt_list    DW_FORM_sec_offset
+    DW_AT value: 0     DW_FORM value: 0
+   2      DW_TAG_variable    \[no children\]
+    DW_AT_name         DW_FORM_string
+    DW_AT_decl_file    DW_FORM_data1
+    DW_AT_decl_line    DW_FORM_data1
+    DW_AT_type         DW_FORM_ref4
+    DW_AT_external     DW_FORM_flag_present
+    DW_AT_location     DW_FORM_exprloc
+    DW_AT value: 0     DW_FORM value: 0
+   3      DW_TAG_base_type    \[no children\]
+    DW_AT_byte_size    DW_FORM_data1
+    DW_AT_encoding     DW_FORM_data1
+    DW_AT_name         DW_FORM_string
+    DW_AT value: 0     DW_FORM value: 0
+
+Contents of the .debug_aranges section:
+
+  Length:                   20
+  Version:                  2
+  Offset into .debug_info:  0x0
+  Pointer Size:             4
+  Segment Size:             0
+
+    Address    Length
+    00000000 00000000 
+
+Raw dump of debug contents of section .debug_line:
+
+  Offset:                      0x0
+  Length:                      45
+  DWARF Version:               2
+  Prologue Length:             39
+  Minimum Instruction Length:  1
+  Initial value of 'is_stmt':  1
+  Line Base:                   -5
+  Line Range:                  14
+  Opcode Base:                 13
+
+ Opcodes:
+  Opcode 1 has 0 args
+  Opcode 2 has 1 args
+  Opcode 3 has 1 args
+  Opcode 4 has 1 args
+  Opcode 5 has 1 args
+  Opcode 6 has 0 args
+  Opcode 7 has 0 args
+  Opcode 8 has 0 args
+  Opcode 9 has 1 args
+  Opcode 10 has 0 args
+  Opcode 11 has 0 args
+  Opcode 12 has 1 args
+
+ The Directory Table is empty.
+
+ The File Name Table \(offset 0x1c\):
+  Entry	Dir	Time	Size	Name
+  1	0	0	0	dw2-compress-3.c
+
+ No Line Number Statements.
+Contents of the .debug_str section:
+
+  0x00000000 2e00474e 55204320 342e382e 33006477 ..GNU C 4.8.3.dw
+  0x00000010 322d636f 6d707265 73732d33 2e6300   2-compress-3.c.
+
diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index 92b4424..26cb7ac 100644
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -384,6 +384,7 @@ if [expr ([istarget "i*86-*-*"] ||  [istarget "x86_64-*-*"]) && [gas_32_check]]
 	run_dump_test "debug1"
 
 	run_dump_test "dw2-compress-2"
+	run_dump_test "dw2-compressed-2"
 
 	run_dump_test "bad-size"
 
@@ -420,6 +421,8 @@ if [expr [istarget "i*86-*-*"] || [istarget "x86_64-*-*"]] then {
 	run_list_test_stdin "list-3" "-al"
 	run_dump_test "dw2-compress-1"
 	run_dump_test "dw2-compress-3"
+	run_dump_test "dw2-compressed-1"
+	run_dump_test "dw2-compressed-3"
     }
 }
 
@@ -735,6 +738,7 @@ if [expr ([istarget "i*86-*-*"] || [istarget "x86_64-*-*"]) && [gas_64_check]] t
 	run_dump_test "x86-64-mpx-branch-2"
 
 	run_dump_test "x86-64-dw2-compress-2"
+	run_dump_test "x86-64-dw2-compressed-2"
 
 	run_dump_test "x86-64-size-1"
 	run_dump_test "x86-64-size-2"
diff --git a/gas/testsuite/gas/i386/x86-64-dw2-compressed-2.d b/gas/testsuite/gas/i386/x86-64-dw2-compressed-2.d
new file mode 100644
index 0000000..1200aec
--- /dev/null
+++ b/gas/testsuite/gas/i386/x86-64-dw2-compressed-2.d
@@ -0,0 +1,7 @@
+#source: x86-64-dw2-compress-2.s
+#as: --compress-debug-sections
+#addr2line: 0x0 0x10 -e
+#name: 64bit DWARF2 debugging information 2 with SHF_COMPRESSED
+
+./dw2-compress-2.c:12
+./dw2-compress-2.c:6
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