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From: Enze Li <enze.li@hotmail.com>
To: Fangrui Song via Gdb-patches <gdb-patches@sourceware.org>
Cc: Alan Modra <amodra@gmail.com>,  Jan Beulich <jbeulich@suse.com>,
	 Nick Clifton <nickc@redhat.com>,
	 Simon Marchi <simon.marchi@polymtl.ca>,
	Fangrui Song <maskray@google.com>,
	 binutils@sourceware.org
Subject: Re: [PATCH v3] binutils, gdb: support zstd compressed debug sections
Date: Sat, 24 Sep 2022 14:53:09 +0800	[thread overview]
Message-ID: <OS3P286MB2152206F3272CCBA30F52370F0509@OS3P286MB2152.JPNP286.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20220923040837.550160-1-maskray@google.com> (Fangrui Song via Gdb-patches's message of "Thu, 22 Sep 2022 21:08:37 -0700")

Hi Fangrui,

One nit, maybe not an important one.

A proper committed message should include a link to the relevant bug on
Bugzilla. Like this,

  Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29563

For more detail, see here[1].

[1] https://sourceware.org/gdb/wiki/ContributionChecklist#Properly_formatted_commit_messages

Thanks,
Enze

On Thu, Sep 22 2022 at 09:08:37 PM -0700, Fangrui Song via Gdb-patches wrote:

> PR29397 PR29563: The new configure option --with-zstd defaults to auto.
> If pkgconfig/libzstd.pc is found, define HAVE_ZSTD and support zstd
> compressed debug sections for most tools.
>
> * bfd: for addr2line, objdump --dwarf, gdb, etc
> * gas: support --compress-debug-sections=zstd
> * ld: support ELFCOMPRESS_ZSTD input and --compress-debug-sections=zstd
> * objcopy: support ELFCOMPRESS_ZSTD input for
>   --decompress-debug-sections and --compress-debug-sections=zstd
> * gdb: support ELFCOMPRESS_ZSTD input.  The bfd change references zstd
>   symbols, so gdb has to link against -lzstd in this patch.
>
> If zstd is not supported, ELFCOMPRESS_ZSTD input triggers an error.  We
> can avoid HAVE_ZSTD if binutils-gdb imports zstd/ like zlib/, but this
> is too heavyweight, so don't do it for now.
>
> ```
> % ld/ld-new a.o
> ld/ld-new: a.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
> ...
>
> % ld/ld-new a.o --compress-debug-sections=zstd
> ld/ld-new: --compress-debug-sections=zstd: ld is not built with zstd support
>
> % binutils/objcopy --compress-debug-sections=zstd a.o b.o
> binutils/objcopy: --compress-debug-sections=zstd: binutils is not built with zstd support
>
> % binutils/objcopy b.o --decompress-debug-sections
> binutils/objcopy: zstd.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
> ...
> ```
> ---
> Changes from v1:
> * use PKG_CHECK_MODULES to check libzstd.pc
>
> Changes from v2:
> * Improve PKG_CHECK_MODULES, autoreconf -vf
> * objcopy: check --compress-debug-sections=zstd in a !HAVE_ZSTD build
> ---
>  bfd/Makefile.am                              |   4 +-
>  bfd/Makefile.in                              |  13 +-
>  bfd/aclocal.m4                               |   2 +
>  bfd/bfd-in.h                                 |   3 +-
>  bfd/bfd-in2.h                                |  11 +-
>  bfd/bfd.c                                    |  26 +-
>  bfd/compress.c                               |  72 +++-
>  bfd/config.in                                |   3 +
>  bfd/configure                                | 268 ++++++++++++-
>  bfd/configure.ac                             |   3 +-
>  bfd/elf.c                                    |  12 +
>  bfd/elfxx-target.h                           |   6 +-
>  bfd/section.c                                |   3 +-
>  binutils/Makefile.in                         |   5 +-
>  binutils/aclocal.m4                          |   1 +
>  binutils/config.in                           |   3 +
>  binutils/configure                           | 135 ++++++-
>  binutils/configure.ac                        |   3 +-
>  binutils/doc/binutils.texi                   |  16 +-
>  binutils/objcopy.c                           |  19 +-
>  binutils/testsuite/binutils-all/compress.exp |  44 +++
>  config/zstd.m4                               |  24 ++
>  configure                                    |  10 +
>  configure.ac                                 |   3 +
>  gas/Makefile.am                              |   4 +-
>  gas/Makefile.in                              |  13 +-
>  gas/aclocal.m4                               |   2 +
>  gas/as.c                                     |  13 +-
>  gas/compress-debug.c                         |  60 ++-
>  gas/compress-debug.h                         |  10 +-
>  gas/config.in                                |   3 +
>  gas/configure                                | 268 ++++++++++++-
>  gas/configure.ac                             |   3 +-
>  gas/doc/as.texi                              |  11 +-
>  gas/write.c                                  |  36 +-
>  gdb/Makefile.in                              |   8 +-
>  gdb/acinclude.m4                             |   3 +-
>  gdb/config.in                                |   3 +
>  gdb/configure                                | 136 ++++++-
>  gdb/configure.ac                             |   4 +-
>  ld/Makefile.am                               |   5 +-
>  ld/Makefile.in                               |  11 +-
>  ld/aclocal.m4                                |   1 +
>  ld/config.in                                 |   3 +
>  ld/configure                                 | 389 ++++++++++++-------
>  ld/configure.ac                              |   7 +-
>  ld/emultempl/elf.em                          |   9 +
>  ld/ld.texi                                   |   5 +
>  ld/ldmain.c                                  |   8 +-
>  ld/lexsup.c                                  |   4 +-
>  ld/testsuite/ld-elf/compress.exp             |  17 +
>  51 files changed, 1470 insertions(+), 255 deletions(-)
>  create mode 100644 config/zstd.m4
>
> diff --git a/bfd/Makefile.am b/bfd/Makefile.am
> index c23dff6cac3..cfe903c63f0 100644
> --- a/bfd/Makefile.am
> +++ b/bfd/Makefile.am
> @@ -57,7 +57,7 @@ ZLIBINC = @zlibinc@
>  
>  WARN_CFLAGS = @WARN_CFLAGS@
>  NO_WERROR = @NO_WERROR@
> -AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
> +AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS)
>  AM_CPPFLAGS = -DBINDIR='"$(bindir)"' -DLIBDIR='"$(libdir)"' @LARGEFILE_CPPFLAGS@
>  if PLUGINS
>  bfdinclude_HEADERS += $(INCDIR)/plugin-api.h
> @@ -776,7 +776,7 @@ ofiles: stamp-ofiles ; @true
>  libbfd_la_SOURCES = $(BFD32_LIBS_CFILES)
>  EXTRA_libbfd_la_SOURCES = $(CFILES)
>  libbfd_la_DEPENDENCIES = $(OFILES) ofiles
> -libbfd_la_LIBADD = `cat ofiles` @SHARED_LIBADD@ $(LIBDL) $(ZLIB)
> +libbfd_la_LIBADD = `cat ofiles` @SHARED_LIBADD@ $(LIBDL) $(ZLIB) $(ZSTD_LIBS)
>  libbfd_la_LDFLAGS += -release `cat libtool-soversion` @SHARED_LDFLAGS@
>  
>  # libtool will build .libs/libbfd.a.  We create libbfd.a in the build
> diff --git a/bfd/Makefile.in b/bfd/Makefile.in
> index 82843d2d61d..6be41a72a59 100644
> --- a/bfd/Makefile.in
> +++ b/bfd/Makefile.in
> @@ -122,10 +122,12 @@ am__aclocal_m4_deps = $(top_srcdir)/../config/acx.m4 \
>  	$(top_srcdir)/../config/lead-dot.m4 \
>  	$(top_srcdir)/../config/nls.m4 \
>  	$(top_srcdir)/../config/override.m4 \
> +	$(top_srcdir)/../config/pkg.m4 \
>  	$(top_srcdir)/../config/plugins.m4 \
>  	$(top_srcdir)/../config/po.m4 \
>  	$(top_srcdir)/../config/progtest.m4 \
> -	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
> +	$(top_srcdir)/../config/zlib.m4 \
> +	$(top_srcdir)/../config/zstd.m4 $(top_srcdir)/../libtool.m4 \
>  	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
>  	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
>  	$(top_srcdir)/bfd.m4 $(top_srcdir)/warning.m4 \
> @@ -399,6 +401,9 @@ PACKAGE_URL = @PACKAGE_URL@
>  PACKAGE_VERSION = @PACKAGE_VERSION@
>  PATH_SEPARATOR = @PATH_SEPARATOR@
>  PKGVERSION = @PKGVERSION@
> +PKG_CONFIG = @PKG_CONFIG@
> +PKG_CONFIG_LIBDIR = @PKG_CONFIG_LIBDIR@
> +PKG_CONFIG_PATH = @PKG_CONFIG_PATH@
>  POSUB = @POSUB@
>  RANLIB = @RANLIB@
>  REPORT_BUGS_TEXI = @REPORT_BUGS_TEXI@
> @@ -416,6 +421,8 @@ WARN_CFLAGS = @WARN_CFLAGS@
>  WARN_CFLAGS_FOR_BUILD = @WARN_CFLAGS_FOR_BUILD@
>  WARN_WRITE_STRINGS = @WARN_WRITE_STRINGS@
>  XGETTEXT = @XGETTEXT@
> +ZSTD_CFLAGS = @ZSTD_CFLAGS@
> +ZSTD_LIBS = @ZSTD_LIBS@
>  abs_builddir = @abs_builddir@
>  abs_srcdir = @abs_srcdir@
>  abs_top_builddir = @abs_top_builddir@
> @@ -520,7 +527,7 @@ libbfd_la_LDFLAGS = $(am__append_1) -release `cat libtool-soversion` \
>  # case both are empty.
>  ZLIB = @zlibdir@ -lz
>  ZLIBINC = @zlibinc@
> -AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
> +AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS)
>  AM_CPPFLAGS = -DBINDIR='"$(bindir)"' -DLIBDIR='"$(libdir)"' \
>  	@LARGEFILE_CPPFLAGS@ @HDEFINES@ @COREFLAG@ @TDEFINES@ \
>  	$(CSEARCH) $(CSWITCHES) $(HAVEVECS) @INCINTL@
> @@ -1199,7 +1206,7 @@ OFILES = $(BFD_BACKENDS) $(BFD_MACHINES) @COREFILE@ @bfd64_libs@
>  libbfd_la_SOURCES = $(BFD32_LIBS_CFILES)
>  EXTRA_libbfd_la_SOURCES = $(CFILES)
>  libbfd_la_DEPENDENCIES = $(OFILES) ofiles
> -libbfd_la_LIBADD = `cat ofiles` @SHARED_LIBADD@ $(LIBDL) $(ZLIB)
> +libbfd_la_LIBADD = `cat ofiles` @SHARED_LIBADD@ $(LIBDL) $(ZLIB) $(ZSTD_LIBS)
>  
>  # libtool will build .libs/libbfd.a.  We create libbfd.a in the build
>  # directory so that we don't have to convert all the programs that use
> diff --git a/bfd/aclocal.m4 b/bfd/aclocal.m4
> index 0f8aa1d4518..09b849dfc87 100644
> --- a/bfd/aclocal.m4
> +++ b/bfd/aclocal.m4
> @@ -1176,10 +1176,12 @@ m4_include([../config/largefile.m4])
>  m4_include([../config/lead-dot.m4])
>  m4_include([../config/nls.m4])
>  m4_include([../config/override.m4])
> +m4_include([../config/pkg.m4])
>  m4_include([../config/plugins.m4])
>  m4_include([../config/po.m4])
>  m4_include([../config/progtest.m4])
>  m4_include([../config/zlib.m4])
> +m4_include([../config/zstd.m4])
>  m4_include([../libtool.m4])
>  m4_include([../ltoptions.m4])
>  m4_include([../ltsugar.m4])
> diff --git a/bfd/bfd-in.h b/bfd/bfd-in.h
> index 8605056aefe..4765ea80536 100644
> --- a/bfd/bfd-in.h
> +++ b/bfd/bfd-in.h
> @@ -342,7 +342,8 @@ enum compressed_debug_section_type
>    COMPRESS_DEBUG_NONE = 0,
>    COMPRESS_DEBUG = 1 << 0,
>    COMPRESS_DEBUG_GNU_ZLIB = COMPRESS_DEBUG | 1 << 1,
> -  COMPRESS_DEBUG_GABI_ZLIB = COMPRESS_DEBUG | 1 << 2
> +  COMPRESS_DEBUG_GABI_ZLIB = COMPRESS_DEBUG | 1 << 2,
> +  COMPRESS_DEBUG_ZSTD = COMPRESS_DEBUG | 1 << 3
>  };
>  
>  /* This structure is used to keep track of stabs in sections
> diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
> index 79fcc4eb912..5c80956c79c 100644
> --- a/bfd/bfd-in2.h
> +++ b/bfd/bfd-in2.h
> @@ -349,7 +349,8 @@ enum compressed_debug_section_type
>    COMPRESS_DEBUG_NONE = 0,
>    COMPRESS_DEBUG = 1 << 0,
>    COMPRESS_DEBUG_GNU_ZLIB = COMPRESS_DEBUG | 1 << 1,
> -  COMPRESS_DEBUG_GABI_ZLIB = COMPRESS_DEBUG | 1 << 2
> +  COMPRESS_DEBUG_GABI_ZLIB = COMPRESS_DEBUG | 1 << 2,
> +  COMPRESS_DEBUG_ZSTD = COMPRESS_DEBUG | 1 << 3
>  };
>  
>  /* This structure is used to keep track of stabs in sections
> @@ -962,7 +963,8 @@ typedef struct bfd_section
>    unsigned int compress_status : 2;
>  #define COMPRESS_SECTION_NONE    0
>  #define COMPRESS_SECTION_DONE    1
> -#define DECOMPRESS_SECTION_SIZED 2
> +#define DECOMPRESS_SECTION_ZLIB  2
> +#define DECOMPRESS_SECTION_ZSTD  3
>  
>    /* The following flags are used by the ELF linker. */
>  
> @@ -6637,12 +6639,14 @@ struct bfd
>  #define BFD_ARCHIVE_FULL_PATH  0x100000
>  
>  #define BFD_CLOSED_BY_CACHE    0x200000
> +  /* Compress sections in this BFD with SHF_COMPRESSED zstd.  */
> +#define BFD_COMPRESS_ZSTD      0x400000
>  
>    /* Flags bits to be saved in bfd_preserve_save.  */
>  #define BFD_FLAGS_SAVED \
>    (BFD_IN_MEMORY | BFD_COMPRESS | BFD_DECOMPRESS | BFD_LINKER_CREATED \
>     | BFD_PLUGIN | BFD_COMPRESS_GABI | BFD_CONVERT_ELF_COMMON \
> -   | BFD_USE_ELF_STT_COMMON)
> +   | BFD_USE_ELF_STT_COMMON | BFD_COMPRESS_ZSTD)
>  
>    /* Flags bits which are for BFD use only.  */
>  #define BFD_FLAGS_FOR_BFD_USE_MASK \
> @@ -7271,6 +7275,7 @@ void bfd_update_compression_header
>  
>  bool bfd_check_compression_header
>     (bfd *abfd, bfd_byte *contents, asection *sec,
> +    unsigned int *ch_type,
>      bfd_size_type *uncompressed_size,
>      unsigned int *uncompressed_alignment_power);
>  
> diff --git a/bfd/bfd.c b/bfd/bfd.c
> index 0a21db11fd6..5f2033bee7a 100644
> --- a/bfd/bfd.c
> +++ b/bfd/bfd.c
> @@ -177,12 +177,15 @@ CODE_FRAGMENT
>  .#define BFD_ARCHIVE_FULL_PATH  0x100000
>  .
>  .#define BFD_CLOSED_BY_CACHE    0x200000
> +
> +.  {* Compress sections in this BFD with SHF_COMPRESSED zstd.  *}
> +.#define BFD_COMPRESS_ZSTD      0x400000
>  .
>  .  {* Flags bits to be saved in bfd_preserve_save.  *}
>  .#define BFD_FLAGS_SAVED \
>  .  (BFD_IN_MEMORY | BFD_COMPRESS | BFD_DECOMPRESS | BFD_LINKER_CREATED \
>  .   | BFD_PLUGIN | BFD_COMPRESS_GABI | BFD_CONVERT_ELF_COMMON \
> -.   | BFD_USE_ELF_STT_COMMON)
> +.   | BFD_USE_ELF_STT_COMMON | BFD_COMPRESS_ZSTD)
>  .
>  .  {* Flags bits which are for BFD use only.  *}
>  .#define BFD_FLAGS_FOR_BFD_USE_MASK \
> @@ -2500,6 +2503,9 @@ bfd_update_compression_header (bfd *abfd, bfd_byte *contents,
>  	{
>  	  const struct elf_backend_data *bed = get_elf_backend_data (abfd);
>  	  struct bfd_elf_section_data * esd = elf_section_data (sec);
> +	  const unsigned int ch_type = abfd->flags & BFD_COMPRESS_ZSTD
> +					   ? ELFCOMPRESS_ZSTD
> +					   : ELFCOMPRESS_ZLIB;
>  
>  	  /* Set the SHF_COMPRESSED bit.  */
>  	  elf_section_flags (sec) |= SHF_COMPRESSED;
> @@ -2507,7 +2513,7 @@ bfd_update_compression_header (bfd *abfd, bfd_byte *contents,
>  	  if (bed->s->elfclass == ELFCLASS32)
>  	    {
>  	      Elf32_External_Chdr *echdr = (Elf32_External_Chdr *) contents;
> -	      bfd_put_32 (abfd, ELFCOMPRESS_ZLIB, &echdr->ch_type);
> +	      bfd_put_32 (abfd, ch_type, &echdr->ch_type);
>  	      bfd_put_32 (abfd, sec->size, &echdr->ch_size);
>  	      bfd_put_32 (abfd, 1u << sec->alignment_power,
>  			  &echdr->ch_addralign);
> @@ -2518,7 +2524,7 @@ bfd_update_compression_header (bfd *abfd, bfd_byte *contents,
>  	  else
>  	    {
>  	      Elf64_External_Chdr *echdr = (Elf64_External_Chdr *) contents;
> -	      bfd_put_32 (abfd, ELFCOMPRESS_ZLIB, &echdr->ch_type);
> +	      bfd_put_32 (abfd, ch_type, &echdr->ch_type);
>  	      bfd_put_32 (abfd, 0, &echdr->ch_reserved);
>  	      bfd_put_64 (abfd, sec->size, &echdr->ch_size);
>  	      bfd_put_64 (abfd, UINT64_C (1) << sec->alignment_power,
> @@ -2553,14 +2559,15 @@ bfd_update_compression_header (bfd *abfd, bfd_byte *contents,
>     SYNOPSIS
>  	bool bfd_check_compression_header
>  	  (bfd *abfd, bfd_byte *contents, asection *sec,
> +	  unsigned int *ch_type,
>  	  bfd_size_type *uncompressed_size,
>  	  unsigned int *uncompressed_alignment_power);
>  
>  DESCRIPTION
> -	Check the compression header at CONTENTS of SEC in ABFD and
> -	store the uncompressed size in UNCOMPRESSED_SIZE and the
> -	uncompressed data alignment in UNCOMPRESSED_ALIGNMENT_POWER
> -	if the compression header is valid.
> +	Check the compression header at CONTENTS of SEC in ABFD and store the
> +	ch_type in CH_TYPE, uncompressed size in UNCOMPRESSED_SIZE, and the
> +	uncompressed data alignment in UNCOMPRESSED_ALIGNMENT_POWER if the
> +	compression header is valid.
>  
>  RETURNS
>  	Return TRUE if the compression header is valid.
> @@ -2569,6 +2576,7 @@ RETURNS
>  bool
>  bfd_check_compression_header (bfd *abfd, bfd_byte *contents,
>  			      asection *sec,
> +			      unsigned int *ch_type,
>  			      bfd_size_type *uncompressed_size,
>  			      unsigned int *uncompressed_alignment_power)
>  {
> @@ -2591,7 +2599,9 @@ bfd_check_compression_header (bfd *abfd, bfd_byte *contents,
>  	  chdr.ch_size = bfd_get_64 (abfd, &echdr->ch_size);
>  	  chdr.ch_addralign = bfd_get_64 (abfd, &echdr->ch_addralign);
>  	}
> -      if (chdr.ch_type == ELFCOMPRESS_ZLIB
> +      *ch_type = chdr.ch_type;
> +      if ((chdr.ch_type == ELFCOMPRESS_ZLIB
> +	   || chdr.ch_type == ELFCOMPRESS_ZSTD)
>  	  && chdr.ch_addralign == (chdr.ch_addralign & -chdr.ch_addralign))
>  	{
>  	  *uncompressed_size = chdr.ch_size;
> diff --git a/bfd/compress.c b/bfd/compress.c
> index b2e39826e38..95c1f4c42d1 100644
> --- a/bfd/compress.c
> +++ b/bfd/compress.c
> @@ -20,18 +20,31 @@
>  
>  #include "sysdep.h"
>  #include <zlib.h>
> +#ifdef HAVE_ZSTD
> +#include <zstd.h>
> +#endif
>  #include "bfd.h"
> +#include "elf-bfd.h"
>  #include "libbfd.h"
>  #include "safe-ctype.h"
>  
>  #define MAX_COMPRESSION_HEADER_SIZE 24
>  
>  static bool
> -decompress_contents (bfd_byte *compressed_buffer,
> +decompress_contents (bool is_zstd, bfd_byte *compressed_buffer,
>  		     bfd_size_type compressed_size,
>  		     bfd_byte *uncompressed_buffer,
>  		     bfd_size_type uncompressed_size)
>  {
> +  if (is_zstd)
> +    {
> +#ifdef HAVE_ZSTD
> +      size_t ret = ZSTD_decompress (uncompressed_buffer, uncompressed_size,
> +				    compressed_buffer, compressed_size);
> +      return !ZSTD_isError (ret);
> +#endif
> +    }
> +
>    z_stream strm;
>    int rc;
>  
> @@ -69,7 +82,7 @@ decompress_contents (bfd_byte *compressed_buffer,
>  }
>  
>  /* Compress data of the size specified in @var{uncompressed_size}
> -   and pointed to by @var{uncompressed_buffer} using zlib and store
> +   and pointed to by @var{uncompressed_buffer} using zlib/zstd and store
>     as the contents field.  This function assumes the contents
>     field was allocated using bfd_malloc() or equivalent.
>  
> @@ -150,9 +163,10 @@ bfd_compress_section_contents (bfd *abfd, sec_ptr sec,
>        sec->size = orig_uncompressed_size;
>        if (decompress)
>  	{
> -	  if (!decompress_contents (uncompressed_buffer
> -				    + orig_compression_header_size,
> -				    zlib_size, buffer, buffer_size))
> +	  if (!decompress_contents (
> +		  sec->compress_status == DECOMPRESS_SECTION_ZSTD,
> +		  uncompressed_buffer + orig_compression_header_size,
> +		  zlib_size, buffer, buffer_size))
>  	    {
>  	      bfd_set_error (bfd_error_bad_value);
>  	      bfd_release (abfd, buffer);
> @@ -175,10 +189,23 @@ bfd_compress_section_contents (bfd *abfd, sec_ptr sec,
>      }
>    else
>      {
> -      if (compress ((Bytef*) buffer + header_size,
> -		    &compressed_size,
> -		    (const Bytef*) uncompressed_buffer,
> -		    uncompressed_size) != Z_OK)
> +      if (abfd->flags & BFD_COMPRESS_ZSTD)
> +	{
> +#if HAVE_ZSTD
> +	  compressed_size = ZSTD_compress (
> +		  buffer + header_size, compressed_size, uncompressed_buffer,
> +		  uncompressed_size, ZSTD_CLEVEL_DEFAULT);
> +	  if (ZSTD_isError (compressed_size))
> +	    {
> +	      bfd_release (abfd, buffer);
> +	      bfd_set_error (bfd_error_bad_value);
> +	      return 0;
> +	    }
> +#endif
> +	}
> +      else if (compress ((Bytef *)buffer + header_size, &compressed_size,
> +			 (const Bytef *)uncompressed_buffer, uncompressed_size)
> +	       != Z_OK)
>  	{
>  	  bfd_release (abfd, buffer);
>  	  bfd_set_error (bfd_error_bad_value);
> @@ -237,6 +264,7 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
>    bfd_size_type save_rawsize;
>    bfd_byte *compressed_buffer;
>    unsigned int compression_header_size;
> +  const unsigned int compress_status = sec->compress_status;
>  
>    if (abfd->direction != write_direction && sec->rawsize != 0)
>      sz = sec->rawsize;
> @@ -248,7 +276,7 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
>        return true;
>      }
>  
> -  switch (sec->compress_status)
> +  switch (compress_status)
>      {
>      case COMPRESS_SECTION_NONE:
>        if (p == NULL)
> @@ -298,7 +326,8 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
>        *ptr = p;
>        return true;
>  
> -    case DECOMPRESS_SECTION_SIZED:
> +    case DECOMPRESS_SECTION_ZLIB:
> +    case DECOMPRESS_SECTION_ZSTD:
>        /* Read in the full compressed section contents.  */
>        compressed_buffer = (bfd_byte *) bfd_malloc (sec->compressed_size);
>        if (compressed_buffer == NULL)
> @@ -316,7 +345,7 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
>        /* Restore rawsize and size.  */
>        sec->rawsize = save_rawsize;
>        sec->size = save_size;
> -      sec->compress_status = DECOMPRESS_SECTION_SIZED;
> +      sec->compress_status = compress_status;
>        if (!ret)
>  	goto fail_compressed;
>  
> @@ -330,8 +359,10 @@ bfd_get_full_section_contents (bfd *abfd, sec_ptr sec, bfd_byte **ptr)
>  	/* Set header size to the zlib header size if it is a
>  	   SHF_COMPRESSED section.  */
>  	compression_header_size = 12;
> -      if (!decompress_contents (compressed_buffer + compression_header_size,
> -				sec->compressed_size - compression_header_size, p, sz))
> +      if (!decompress_contents (compress_status == DECOMPRESS_SECTION_ZSTD,
> +				compressed_buffer + compression_header_size,
> +				sec->compressed_size - compression_header_size,
> +				p, sz))
>  	{
>  	  bfd_set_error (bfd_error_bad_value);
>  	  if (p != *ptr)
> @@ -381,7 +412,8 @@ DESCRIPTION
>  void
>  bfd_cache_section_contents (asection *sec, void *contents)
>  {
> -  if (sec->compress_status == DECOMPRESS_SECTION_SIZED)
> +  if (sec->compress_status == DECOMPRESS_SECTION_ZLIB
> +      || sec->compress_status == DECOMPRESS_SECTION_ZSTD)
>      sec->compress_status = COMPRESS_SECTION_DONE;
>    sec->contents = contents;
>    sec->flags |= SEC_IN_MEMORY;
> @@ -418,6 +450,7 @@ bfd_is_section_compressed_with_header (bfd *abfd, sec_ptr sec,
>    int compression_header_size;
>    int header_size;
>    unsigned int saved = sec->compress_status;
> +  unsigned int ch_type;
>    bool compressed;
>  
>    *uncompressed_align_pow_p = 0;
> @@ -448,7 +481,7 @@ bfd_is_section_compressed_with_header (bfd *abfd, sec_ptr sec,
>      {
>        if (compression_header_size != 0)
>  	{
> -	  if (!bfd_check_compression_header (abfd, header, sec,
> +	  if (!bfd_check_compression_header (abfd, header, sec, &ch_type,
>  					     uncompressed_size_p,
>  					     uncompressed_align_pow_p))
>  	    compression_header_size = -1;
> @@ -507,7 +540,7 @@ SYNOPSIS
>  DESCRIPTION
>  	Record compressed section size, update section size with
>  	decompressed size and set compress_status to
> -	DECOMPRESS_SECTION_SIZED.
> +	DECOMPRESS_SECTION_{ZLIB,ZSTD}.
>  
>  	Return @code{FALSE} if the section is not a valid compressed
>  	section.  Otherwise, return @code{TRUE}.
> @@ -521,6 +554,7 @@ bfd_init_section_decompress_status (bfd *abfd, sec_ptr sec)
>    int header_size;
>    bfd_size_type uncompressed_size;
>    unsigned int uncompressed_alignment_power = 0;
> +  unsigned int ch_type;
>    z_stream strm;
>  
>    compression_header_size = bfd_get_compression_header_size (abfd, sec);
> @@ -550,6 +584,7 @@ bfd_init_section_decompress_status (bfd *abfd, sec_ptr sec)
>        uncompressed_size = bfd_getb64 (header + 4);
>      }
>    else if (!bfd_check_compression_header (abfd, header, sec,
> +					  &ch_type,
>  					  &uncompressed_size,
>  					  &uncompressed_alignment_power))
>      {
> @@ -569,7 +604,8 @@ bfd_init_section_decompress_status (bfd *abfd, sec_ptr sec)
>    sec->compressed_size = sec->size;
>    sec->size = uncompressed_size;
>    bfd_set_section_alignment (sec, uncompressed_alignment_power);
> -  sec->compress_status = DECOMPRESS_SECTION_SIZED;
> +  sec->compress_status = ch_type == ELFCOMPRESS_ZSTD ? DECOMPRESS_SECTION_ZSTD
> +						     : DECOMPRESS_SECTION_ZLIB;
>  
>    return true;
>  }
> diff --git a/bfd/config.in b/bfd/config.in
> index f54a3cacbea..a59304e0a66 100644
> --- a/bfd/config.in
> +++ b/bfd/config.in
> @@ -232,6 +232,9 @@
>  /* Define to 1 if you have the <windows.h> header file. */
>  #undef HAVE_WINDOWS_H
>  
> +/* Define to 1 if zstd is enabled. */
> +#undef HAVE_ZSTD
> +
>  /* Define to the sub-directory in which libtool stores uninstalled libraries.
>     */
>  #undef LT_OBJDIR
> diff --git a/bfd/configure b/bfd/configure
> index 075d2ee0a1b..d905a7bf7a8 100755
> --- a/bfd/configure
> +++ b/bfd/configure
> @@ -652,6 +652,11 @@ TDEFINES
>  SHARED_LIBADD
>  SHARED_LDFLAGS
>  LIBM
> +ZSTD_LIBS
> +ZSTD_CFLAGS
> +PKG_CONFIG_LIBDIR
> +PKG_CONFIG_PATH
> +PKG_CONFIG
>  zlibinc
>  zlibdir
>  EXEEXT_FOR_BUILD
> @@ -839,6 +844,7 @@ enable_maintainer_mode
>  enable_install_libbfd
>  enable_nls
>  with_system_zlib
> +with_zstd
>  '
>        ac_precious_vars='build_alias
>  host_alias
> @@ -848,7 +854,12 @@ CFLAGS
>  LDFLAGS
>  LIBS
>  CPPFLAGS
> -CPP'
> +CPP
> +PKG_CONFIG
> +PKG_CONFIG_PATH
> +PKG_CONFIG_LIBDIR
> +ZSTD_CFLAGS
> +ZSTD_LIBS'
>  
>  
>  # Initialize some variables set by options.
> @@ -1511,6 +1522,8 @@ Optional Packages:
>                            Binutils"
>    --with-bugurl=URL       Direct users to URL to report a bug
>    --with-system-zlib      use installed libz
> +  --with-zstd             support zstd compressed debug sections
> +                          (default=auto)
>  
>  Some influential environment variables:
>    CC          C compiler command
> @@ -1521,6 +1534,13 @@ Some influential environment variables:
>    CPPFLAGS    (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
>                you have headers in a nonstandard directory <include dir>
>    CPP         C preprocessor
> +  PKG_CONFIG  path to pkg-config utility
> +  PKG_CONFIG_PATH
> +              directories to add to pkg-config's search path
> +  PKG_CONFIG_LIBDIR
> +              path overriding pkg-config's built-in search path
> +  ZSTD_CFLAGS C compiler flags for ZSTD, overriding pkg-config
> +  ZSTD_LIBS   linker flags for ZSTD, overriding pkg-config
>  
>  Use these variables to override the choices made by `configure' or to help
>  it to find libraries and programs with nonstandard names/locations.
> @@ -11086,7 +11106,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 11089 "configure"
> +#line 11109 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -11192,7 +11212,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 11195 "configure"
> +#line 11215 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -12995,7 +13015,7 @@ $as_echo "#define USE_BINARY_FOPEN 1" >>confdefs.h
>   ;;
>  esac
>  
> -# Link in zlib if we can.  This allows us to read compressed debug sections.
> +# Link in zlib/zstd if we can.  This allows us to read compressed debug sections.
>  # This is used only by compress.c.
>  
>    # Use the system's zlib library.
> @@ -13015,6 +13035,246 @@ fi
>  
>  
>  
> +
> +
> +
> +
> +
> +
> +if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
> +	if test -n "$ac_tool_prefix"; then
> +  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
> +set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> +$as_echo_n "checking for $ac_word... " >&6; }
> +if ${ac_cv_path_PKG_CONFIG+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  case $PKG_CONFIG in
> +  [\\/]* | ?:[\\/]*)
> +  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
> +  ;;
> +  *)
> +  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> +for as_dir in $PATH
> +do
> +  IFS=$as_save_IFS
> +  test -z "$as_dir" && as_dir=.
> +    for ac_exec_ext in '' $ac_executable_extensions; do
> +  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> +    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> +    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> +    break 2
> +  fi
> +done
> +  done
> +IFS=$as_save_IFS
> +
> +  ;;
> +esac
> +fi
> +PKG_CONFIG=$ac_cv_path_PKG_CONFIG
> +if test -n "$PKG_CONFIG"; then
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
> +$as_echo "$PKG_CONFIG" >&6; }
> +else
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +fi
> +
> +
> +fi
> +if test -z "$ac_cv_path_PKG_CONFIG"; then
> +  ac_pt_PKG_CONFIG=$PKG_CONFIG
> +  # Extract the first word of "pkg-config", so it can be a program name with args.
> +set dummy pkg-config; ac_word=$2
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> +$as_echo_n "checking for $ac_word... " >&6; }
> +if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  case $ac_pt_PKG_CONFIG in
> +  [\\/]* | ?:[\\/]*)
> +  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
> +  ;;
> +  *)
> +  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> +for as_dir in $PATH
> +do
> +  IFS=$as_save_IFS
> +  test -z "$as_dir" && as_dir=.
> +    for ac_exec_ext in '' $ac_executable_extensions; do
> +  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> +    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> +    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> +    break 2
> +  fi
> +done
> +  done
> +IFS=$as_save_IFS
> +
> +  ;;
> +esac
> +fi
> +ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
> +if test -n "$ac_pt_PKG_CONFIG"; then
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
> +$as_echo "$ac_pt_PKG_CONFIG" >&6; }
> +else
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +fi
> +
> +  if test "x$ac_pt_PKG_CONFIG" = x; then
> +    PKG_CONFIG=""
> +  else
> +    case $cross_compiling:$ac_tool_warned in
> +yes:)
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
> +$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
> +ac_tool_warned=yes ;;
> +esac
> +    PKG_CONFIG=$ac_pt_PKG_CONFIG
> +  fi
> +else
> +  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
> +fi
> +
> +fi
> +if test -n "$PKG_CONFIG"; then
> +	_pkg_min_version=0.9.0
> +	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
> +$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
> +	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
> +		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +	else
> +		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +		PKG_CONFIG=""
> +	fi
> +fi
> +
> +
> +# Check whether --with-zstd was given.
> +if test "${with_zstd+set}" = set; then :
> +  withval=$with_zstd;
> +else
> +  with_zstd=auto
> +fi
> +
> +
> +if test "$with_zstd" != no; then
> +
> +pkg_failed=no
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libzstd" >&5
> +$as_echo_n "checking for libzstd... " >&6; }
> +
> +if test -n "$ZSTD_CFLAGS"; then
> +    pkg_cv_ZSTD_CFLAGS="$ZSTD_CFLAGS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_CFLAGS=`$PKG_CONFIG --cflags "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +if test -n "$ZSTD_LIBS"; then
> +    pkg_cv_ZSTD_LIBS="$ZSTD_LIBS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_LIBS=`$PKG_CONFIG --libs "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +
> +if test $pkg_failed = no; then
> +  pkg_save_LDFLAGS="$LDFLAGS"
> +  LDFLAGS="$LDFLAGS $pkg_cv_ZSTD_LIBS"
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +
> +int
> +main ()
> +{
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_link "$LINENO"; then :
> +
> +else
> +  pkg_failed=yes
> +fi
> +rm -f core conftest.err conftest.$ac_objext \
> +    conftest$ac_exeext conftest.$ac_ext
> +  LDFLAGS=$pkg_save_LDFLAGS
> +fi
> +
> +
> +
> +if test $pkg_failed = yes; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
> +        _pkg_short_errors_supported=yes
> +else
> +        _pkg_short_errors_supported=no
> +fi
> +        if test $_pkg_short_errors_supported = yes; then
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libzstd" 2>&1`
> +        else
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libzstd" 2>&1`
> +        fi
> +	# Put the nasty error message in config.log where it belongs
> +	echo "$ZSTD_PKG_ERRORS" >&5
> +
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +elif test $pkg_failed = untried; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +else
> +	ZSTD_CFLAGS=$pkg_cv_ZSTD_CFLAGS
> +	ZSTD_LIBS=$pkg_cv_ZSTD_LIBS
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +
> +
> +$as_echo "#define HAVE_ZSTD 1" >>confdefs.h
> +
> +
> +fi
> +fi
> +
> +
>  save_CFLAGS="$CFLAGS"
>  CFLAGS="$CFLAGS -Werror"
>  { $as_echo "$as_me:${as_lineno-$LINENO}: checking compiler support for hidden visibility" >&5
> diff --git a/bfd/configure.ac b/bfd/configure.ac
> index 28f3d1afce6..d1b2f76b31a 100644
> --- a/bfd/configure.ac
> +++ b/bfd/configure.ac
> @@ -230,9 +230,10 @@ AC_CHECK_DECLS([basename, ffs, stpcpy, asprintf, vasprintf, strnlen])
>  
>  BFD_BINARY_FOPEN
>  
> -# Link in zlib if we can.  This allows us to read compressed debug sections.
> +# Link in zlib/zstd if we can.  This allows us to read compressed debug sections.
>  # This is used only by compress.c.
>  AM_ZLIB
> +AM_ZSTD
>  
>  save_CFLAGS="$CFLAGS"
>  CFLAGS="$CFLAGS -Werror"
> diff --git a/bfd/elf.c b/bfd/elf.c
> index 16cea4f8aeb..e52fa458a5a 100644
> --- a/bfd/elf.c
> +++ b/bfd/elf.c
> @@ -1260,6 +1260,18 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
>  		 abfd, name);
>  	      return false;
>  	    }
> +#ifndef HAVE_ZSTD
> +	  if (newsect->compress_status == DECOMPRESS_SECTION_ZSTD)
> +	    {
> +	      _bfd_error_handler
> +		  /* xgettext:c-format */
> +		  (_ ("%pB: section %s is compressed with zstd, but BFD "
> +		      "is not built with zstd support"),
> +		   abfd, name);
> +	      newsect->compress_status = COMPRESS_SECTION_NONE;
> +	      return false;
> +	    }
> +#endif
>  	}
>  
>        if (abfd->is_linker_input)
> diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h
> index feaba84bf2e..ca600bb5ddf 100644
> --- a/bfd/elfxx-target.h
> +++ b/bfd/elfxx-target.h
> @@ -989,7 +989,8 @@ const bfd_target TARGET_BIG_SYM =
>    /* object_flags: mask of all file flags */
>    (HAS_RELOC | EXEC_P | HAS_LINENO | HAS_DEBUG | HAS_SYMS | HAS_LOCALS
>     | DYNAMIC | WP_TEXT | D_PAGED | BFD_COMPRESS | BFD_DECOMPRESS
> -   | BFD_COMPRESS_GABI | BFD_CONVERT_ELF_COMMON | BFD_USE_ELF_STT_COMMON),
> +   | BFD_COMPRESS_GABI | BFD_COMPRESS_ZSTD | BFD_CONVERT_ELF_COMMON
> +   | BFD_USE_ELF_STT_COMMON),
>  
>    /* section_flags: mask of all section flags */
>    (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC | SEC_READONLY
> @@ -1093,7 +1094,8 @@ const bfd_target TARGET_LITTLE_SYM =
>    /* object_flags: mask of all file flags */
>    (HAS_RELOC | EXEC_P | HAS_LINENO | HAS_DEBUG | HAS_SYMS | HAS_LOCALS
>     | DYNAMIC | WP_TEXT | D_PAGED | BFD_COMPRESS | BFD_DECOMPRESS
> -   | BFD_COMPRESS_GABI | BFD_CONVERT_ELF_COMMON | BFD_USE_ELF_STT_COMMON),
> +   | BFD_COMPRESS_GABI | BFD_COMPRESS_ZSTD | BFD_CONVERT_ELF_COMMON
> +   | BFD_USE_ELF_STT_COMMON),
>  
>    /* section_flags: mask of all section flags */
>    (SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD | SEC_RELOC | SEC_READONLY
> diff --git a/bfd/section.c b/bfd/section.c
> index c7a02d729f2..614570e976e 100644
> --- a/bfd/section.c
> +++ b/bfd/section.c
> @@ -392,7 +392,8 @@ CODE_FRAGMENT
>  .  unsigned int compress_status : 2;
>  .#define COMPRESS_SECTION_NONE    0
>  .#define COMPRESS_SECTION_DONE    1
> -.#define DECOMPRESS_SECTION_SIZED 2
> +.#define DECOMPRESS_SECTION_ZLIB  2
> +.#define DECOMPRESS_SECTION_ZSTD  3
>  .
>  .  {* The following flags are used by the ELF linker. *}
>  .
> diff --git a/binutils/Makefile.in b/binutils/Makefile.in
> index 78d32b350e3..6de4e239408 100644
> --- a/binutils/Makefile.in
> +++ b/binutils/Makefile.in
> @@ -156,7 +156,8 @@ am__aclocal_m4_deps = $(top_srcdir)/../bfd/acinclude.m4 \
>  	$(top_srcdir)/../config/plugins.m4 \
>  	$(top_srcdir)/../config/po.m4 \
>  	$(top_srcdir)/../config/progtest.m4 \
> -	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
> +	$(top_srcdir)/../config/zlib.m4 \
> +	$(top_srcdir)/../config/zstd.m4 $(top_srcdir)/../libtool.m4 \
>  	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
>  	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
>  	$(top_srcdir)/../bfd/version.m4 \
> @@ -575,6 +576,8 @@ WARN_WRITE_STRINGS = @WARN_WRITE_STRINGS@
>  XGETTEXT = @XGETTEXT@
>  YACC = `if [ -f ../bison/bison ]; then echo ../bison/bison -y -L$(srcdir)/../bison/; else echo @YACC@; fi`
>  YFLAGS = -d
> +ZSTD_CFLAGS = @ZSTD_CFLAGS@
> +ZSTD_LIBS = @ZSTD_LIBS@
>  abs_builddir = @abs_builddir@
>  abs_srcdir = @abs_srcdir@
>  abs_top_builddir = @abs_top_builddir@
> diff --git a/binutils/aclocal.m4 b/binutils/aclocal.m4
> index a877fa7f873..28271f56279 100644
> --- a/binutils/aclocal.m4
> +++ b/binutils/aclocal.m4
> @@ -1205,6 +1205,7 @@ m4_include([../config/plugins.m4])
>  m4_include([../config/po.m4])
>  m4_include([../config/progtest.m4])
>  m4_include([../config/zlib.m4])
> +m4_include([../config/zstd.m4])
>  m4_include([../libtool.m4])
>  m4_include([../ltoptions.m4])
>  m4_include([../ltsugar.m4])
> diff --git a/binutils/config.in b/binutils/config.in
> index c5fb919aa95..bee8c07e2f7 100644
> --- a/binutils/config.in
> +++ b/binutils/config.in
> @@ -157,6 +157,9 @@
>  /* Define to 1 if you have the <windows.h> header file. */
>  #undef HAVE_WINDOWS_H
>  
> +/* Define to 1 if zstd is enabled. */
> +#undef HAVE_ZSTD
> +
>  /* Define as const if the declaration of iconv() needs const. */
>  #undef ICONV_CONST
>  
> diff --git a/binutils/configure b/binutils/configure
> index 1c518227f57..54d0f184da1 100755
> --- a/binutils/configure
> +++ b/binutils/configure
> @@ -650,6 +650,8 @@ LTLIBICONV
>  LIBICONV
>  MSGPACK_LIBS
>  MSGPACK_CFLAGS
> +ZSTD_LIBS
> +ZSTD_CFLAGS
>  zlibinc
>  zlibdir
>  DEMANGLER_NAME
> @@ -832,6 +834,7 @@ enable_build_warnings
>  enable_nls
>  enable_maintainer_mode
>  with_system_zlib
> +with_zstd
>  with_msgpack
>  enable_rpath
>  with_libiconv_prefix
> @@ -853,6 +856,8 @@ DEBUGINFOD_CFLAGS
>  DEBUGINFOD_LIBS
>  YACC
>  YFLAGS
> +ZSTD_CFLAGS
> +ZSTD_LIBS
>  MSGPACK_CFLAGS
>  MSGPACK_LIBS'
>  
> @@ -1517,6 +1522,8 @@ Optional Packages:
>    --with-debuginfod       Enable debuginfo lookups with debuginfod
>                            (auto/yes/no)
>    --with-system-zlib      use installed libz
> +  --with-zstd             support zstd compressed debug sections
> +                          (default=auto)
>    --with-msgpack          Enable msgpack support (auto/yes/no)
>    --with-gnu-ld           assume the C compiler uses GNU ld default=no
>    --with-libiconv-prefix[=DIR]  search for libiconv in DIR/include and DIR/lib
> @@ -1547,6 +1554,8 @@ Some influential environment variables:
>    YFLAGS      The list of arguments that will be passed by default to $YACC.
>                This script will default YFLAGS to the empty string to avoid a
>                default value of `-d' given by some make applications.
> +  ZSTD_CFLAGS C compiler flags for ZSTD, overriding pkg-config
> +  ZSTD_LIBS   linker flags for ZSTD, overriding pkg-config
>    MSGPACK_CFLAGS
>                C compiler flags for MSGPACK, overriding pkg-config
>    MSGPACK_LIBS
> @@ -10804,7 +10813,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 10807 "configure"
> +#line 10816 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -10910,7 +10919,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 10913 "configure"
> +#line 10922 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -13468,7 +13477,7 @@ cat >>confdefs.h <<_ACEOF
>  _ACEOF
>  
>  
> -# Link in zlib if we can.  This allows us to read compressed debug
> +# Link in zlib/zstd if we can.  This allows us to read compressed debug
>  # sections.  This is used only by readelf.c (objdump uses bfd for
>  # reading compressed sections).
>  
> @@ -13490,6 +13499,126 @@ fi
>  
>  
>  
> +# Check whether --with-zstd was given.
> +if test "${with_zstd+set}" = set; then :
> +  withval=$with_zstd;
> +else
> +  with_zstd=auto
> +fi
> +
> +
> +if test "$with_zstd" != no; then
> +
> +pkg_failed=no
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libzstd" >&5
> +$as_echo_n "checking for libzstd... " >&6; }
> +
> +if test -n "$ZSTD_CFLAGS"; then
> +    pkg_cv_ZSTD_CFLAGS="$ZSTD_CFLAGS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_CFLAGS=`$PKG_CONFIG --cflags "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +if test -n "$ZSTD_LIBS"; then
> +    pkg_cv_ZSTD_LIBS="$ZSTD_LIBS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_LIBS=`$PKG_CONFIG --libs "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +
> +if test $pkg_failed = no; then
> +  pkg_save_LDFLAGS="$LDFLAGS"
> +  LDFLAGS="$LDFLAGS $pkg_cv_ZSTD_LIBS"
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +
> +int
> +main ()
> +{
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_link "$LINENO"; then :
> +
> +else
> +  pkg_failed=yes
> +fi
> +rm -f core conftest.err conftest.$ac_objext \
> +    conftest$ac_exeext conftest.$ac_ext
> +  LDFLAGS=$pkg_save_LDFLAGS
> +fi
> +
> +
> +
> +if test $pkg_failed = yes; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
> +        _pkg_short_errors_supported=yes
> +else
> +        _pkg_short_errors_supported=no
> +fi
> +        if test $_pkg_short_errors_supported = yes; then
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libzstd" 2>&1`
> +        else
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libzstd" 2>&1`
> +        fi
> +	# Put the nasty error message in config.log where it belongs
> +	echo "$ZSTD_PKG_ERRORS" >&5
> +
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +elif test $pkg_failed = untried; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +else
> +	ZSTD_CFLAGS=$pkg_cv_ZSTD_CFLAGS
> +	ZSTD_LIBS=$pkg_cv_ZSTD_LIBS
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +
> +
> +$as_echo "#define HAVE_ZSTD 1" >>confdefs.h
> +
> +
> +fi
> +fi
> +
> +
> +
>  case "${host}" in
>  *-*-msdos* | *-*-go32* | *-*-mingw32* | *-*-cygwin* | *-*-windows*)
>  
> diff --git a/binutils/configure.ac b/binutils/configure.ac
> index ec002d3f88f..c152b7f6733 100644
> --- a/binutils/configure.ac
> +++ b/binutils/configure.ac
> @@ -265,10 +265,11 @@ fi
>  
>  AC_CHECK_DECLS([asprintf, environ, getc_unlocked, stpcpy, strnlen])
>  
> -# Link in zlib if we can.  This allows us to read compressed debug
> +# Link in zlib/zstd if we can.  This allows us to read compressed debug
>  # sections.  This is used only by readelf.c (objdump uses bfd for
>  # reading compressed sections).
>  AM_ZLIB
> +AM_ZSTD
>  
>  BFD_BINARY_FOPEN
>  
> diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
> index 1499db5728c..34a4164eb94 100644
> --- a/binutils/doc/binutils.texi
> +++ b/binutils/doc/binutils.texi
> @@ -2159,21 +2159,23 @@ ELF ABI.  Note - if compression would actually make a section
>  @itemx --compress-debug-sections=zlib
>  @itemx --compress-debug-sections=zlib-gnu
>  @itemx --compress-debug-sections=zlib-gabi
> +@itemx --compress-debug-sections=zstd
>  For ELF files, these options control how DWARF debug sections are
>  compressed.  @option{--compress-debug-sections=none} is equivalent
>  to @option{--decompress-debug-sections}.
>  @option{--compress-debug-sections=zlib} and
>  @option{--compress-debug-sections=zlib-gabi} are equivalent to
>  @option{--compress-debug-sections}.
> -@option{--compress-debug-sections=zlib-gnu} compresses DWARF debug
> -sections using zlib.  The debug sections are renamed to begin with
> -@samp{.zdebug} instead of @samp{.debug}.  Note - if compression would
> -actually make a section @emph{larger}, then it is not compressed nor
> -renamed.
> +@option{--compress-debug-sections=zlib-gnu} compresses DWARF debug sections
> +using the obsoleted zlib-gnu format.  The debug sections are renamed to begin
> +with @samp{.zdebug}.
> +@option{--compress-debug-sections=zstd} compresses DWARF debug
> +sections using zstd.  Note - if compression would actually make a section
> +@emph{larger}, then it is not compressed nor renamed.
>  
>  @item --decompress-debug-sections
> -Decompress DWARF debug sections using zlib.  The original section
> -names of the compressed sections are restored.
> +Decompress DWARF debug sections.  For a @samp{.zdebug} section, the original
> +name is restored.
>  
>  @item --elf-stt-common=yes
>  @itemx --elf-stt-common=no
> diff --git a/binutils/objcopy.c b/binutils/objcopy.c
> index 43261756a42..fc668f00bbc 100644
> --- a/binutils/objcopy.c
> +++ b/binutils/objcopy.c
> @@ -232,7 +232,8 @@ static enum
>    compress_zlib = compress | 1 << 1,
>    compress_gnu_zlib = compress | 1 << 2,
>    compress_gabi_zlib = compress | 1 << 3,
> -  decompress = 1 << 4
> +  compress_zstd = compress | 1 << 4,
> +  decompress = 1 << 5
>  } do_debug_sections = nothing;
>  
>  /* Whether to generate ELF common symbols with the STT_COMMON type.  */
> @@ -678,8 +679,8 @@ copy_usage (FILE *stream, int exit_status)
>                                     <commit>\n\
>       --subsystem <name>[:<version>]\n\
>                                     Set PE subsystem to <name> [& <version>]\n\
> -     --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi}]\n\
> -                                   Compress DWARF debug sections using zlib\n\
> +     --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi|zstd}]\n\
> +				   Compress DWARF debug sections\n\
>       --decompress-debug-sections   Decompress DWARF debug sections using zlib\n\
>       --elf-stt-common=[yes|no]     Generate ELF common symbols with STT_COMMON\n\
>                                       type\n\
> @@ -2659,7 +2660,8 @@ copy_object (bfd *ibfd, bfd *obfd, const bfd_arch_info_type *input_arch)
>        if ((do_debug_sections & compress) != 0
>  	  && do_debug_sections != compress)
>  	{
> -	  non_fatal (_("--compress-debug-sections=[zlib|zlib-gnu|zlib-gabi] is unsupported on `%s'"),
> +	  non_fatal (_ ("--compress-debug-sections=[zlib|zlib-gnu|zlib-gabi|"
> +			"zstd] is unsupported on `%s'"),
>  		     bfd_get_archive_filename (ibfd));
>  	  return false;
>  	}
> @@ -3807,6 +3809,13 @@ copy_file (const char *input_filename, const char *output_filename, int ofd,
>        if (do_debug_sections != compress_gnu_zlib)
>  	ibfd->flags |= BFD_COMPRESS_GABI;
>        break;
> +    case compress_zstd:
> +      ibfd->flags |= BFD_COMPRESS | BFD_COMPRESS_GABI | BFD_COMPRESS_ZSTD;
> +#ifndef HAVE_ZSTD
> +      fatal (_ ("--compress-debug-sections=zstd: binutils is not built with "
> +		"zstd support"));
> +#endif
> +      break;
>      case decompress:
>        ibfd->flags |= BFD_DECOMPRESS;
>        break;
> @@ -5469,6 +5478,8 @@ copy_main (int argc, char *argv[])
>  		do_debug_sections = compress_gnu_zlib;
>  	      else if (strcasecmp (optarg, "zlib-gabi") == 0)
>  		do_debug_sections = compress_gabi_zlib;
> +	      else if (strcasecmp (optarg, "zstd") == 0)
> +		do_debug_sections = compress_zstd;
>  	      else
>  		fatal (_("unrecognized --compress-debug-sections type `%s'"),
>  		       optarg);
> diff --git a/binutils/testsuite/binutils-all/compress.exp b/binutils/testsuite/binutils-all/compress.exp
> index c88da74a987..4e74c824664 100644
> --- a/binutils/testsuite/binutils-all/compress.exp
> +++ b/binutils/testsuite/binutils-all/compress.exp
> @@ -576,6 +576,50 @@ if { [regexp_diff objdump.out $srcdir/$subdir/dw2-3gabi.W] } then {
>      pass "$testname"
>  }
>  
> +if { [binutils_assemble_flags $srcdir/$subdir/dw2-1.S ${compressedfile}zstd.o --compress-debug-sections=zstd] } then {
> +    set testname "objcopy compress debug sections with zstd"
> +    set got [binutils_run $OBJCOPY "--compress-debug-sections=zstd ${testfile}.o ${copyfile}zstd.o"]
> +    if ![string match "" $got] then {
> +	fail "objcopy ($testname)"
> +	return
> +    }
> +    send_log "cmp ${compressedfile}zstd.o ${copyfile}zstd.o\n"
> +    verbose "cmp ${compressedfile}zstd.o ${copyfile}zstd.o"
> +    set src1 ${compressedfile}zstd.o
> +    set src2 ${copyfile}zstd.o
> +    set status [remote_exec build cmp "${src1} ${src2}"]
> +    set exec_output [lindex $status 1]
> +    set exec_output [prune_warnings $exec_output]
> +    if ![string match "" $exec_output] then {
> +	send_log "$exec_output\n"
> +	verbose "$exec_output" 1
> +	fail "objcopy ($testname)"
> +    } else {
> +	pass "objcopy ($testname)"
> +    }
> +
> +    set testname "objcopy decompress compressed debug sections with zstd"
> +    set got [binutils_run $OBJCOPY "--decompress-debug-sections ${compressedfile}zstd.o ${copyfile}zstd.o"]
> +    if ![string match "" $got] then {
> +	fail "objcopy ($testname)"
> +	return
> +    }
> +    send_log "cmp ${testfile}.o ${copyfile}zstd.o\n"
> +    verbose "cmp ${testfile}.o ${copyfile}zstd.o"
> +    set src1 ${testfile}.o
> +    set src2 ${copyfile}zstd.o
> +    set status [remote_exec build cmp "${src1} ${src2}"]
> +    set exec_output [lindex $status 1]
> +    set exec_output [prune_warnings $exec_output]
> +    if ![string match "" $exec_output] then {
> +	send_log "$exec_output\n"
> +	verbose "$exec_output" 1
> +	fail "objcopy ($testname)"
> +    } else {
> +	pass "objcopy ($testname)"
> +    }
> +}
> +
>  proc convert_test { testname  as_flags  objcop_flags } {
>      global srcdir
>      global subdir
> diff --git a/config/zstd.m4 b/config/zstd.m4
> new file mode 100644
> index 00000000000..93ae17b89d3
> --- /dev/null
> +++ b/config/zstd.m4
> @@ -0,0 +1,24 @@
> +dnl Copyright (C) 2022 Free Software Foundation, Inc.
> +dnl This file is free software, distributed under the terms of the GNU
> +dnl General Public License.  As a special exception to the GNU General
> +dnl Public License, this file may be distributed as part of a program
> +dnl that contains a configuration script generated by Autoconf, under
> +dnl the same distribution terms as the rest of that program.
> +
> +dnl Enable features using the zstd library.
> +AC_DEFUN([AM_ZSTD],
> +[
> +AC_ARG_WITH(zstd,
> +  [AS_HELP_STRING([--with-zstd], [support zstd compressed debug sections (default=auto)])],
> +  [], [with_zstd=auto])
> +
> +if test "$with_zstd" != no; then
> +  PKG_CHECK_MODULES(ZSTD, [libzstd], [
> +    AC_DEFINE(HAVE_ZSTD, 1, [Define to 1 if zstd is enabled.])
> +  ], [
> +    if test "$with_zstd" = yes; then
> +      AC_MSG_ERROR([--with-zstd was given, but pkgconfig/libzstd.pc is not found])
> +    fi
> +  ])
> +fi
> +])
> diff --git a/configure b/configure
> index d75f47a1e95..f14e0efd675 100755
> --- a/configure
> +++ b/configure
> @@ -785,6 +785,7 @@ ac_user_opts='
>  enable_option_checking
>  with_build_libsubdir
>  with_system_zlib
> +with_zstd
>  enable_as_accelerator_for
>  enable_offload_targets
>  enable_gold
> @@ -1567,6 +1568,8 @@ Optional Packages:
>    --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
>    --with-build-libsubdir=DIR  Directory where to find libraries for build system
>    --with-system-zlib      use installed libz
> +  --with-zstd             Support zstd compressed debug sections
> +                          (default=auto)
>    --with-mpc=PATH         specify prefix directory for installed MPC package.
>                            Equivalent to --with-mpc-include=PATH/include plus
>                            --with-mpc-lib=PATH/lib
> @@ -2925,6 +2928,13 @@ if test x$with_system_zlib = xyes ; then
>    noconfigdirs="$noconfigdirs zlib"
>  fi
>  
> +
> +# Check whether --with-zstd was given.
> +if test "${with_zstd+set}" = set; then :
> +  withval=$with_zstd;
> +fi
> +
> +
>  # Don't compile the bundled readline/libreadline.a if --with-system-readline
>  # is provided.
>  if test x$with_system_readline = xyes ; then
> diff --git a/configure.ac b/configure.ac
> index ae18d436aca..0152c69292e 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -246,6 +246,9 @@ if test x$with_system_zlib = xyes ; then
>    noconfigdirs="$noconfigdirs zlib"
>  fi
>  
> +AC_ARG_WITH(zstd,
> +[AS_HELP_STRING([--with-zstd], [Support zstd compressed debug sections (default=auto)])])
> +
>  # Don't compile the bundled readline/libreadline.a if --with-system-readline
>  # is provided.
>  if test x$with_system_readline = xyes ; then
> diff --git a/gas/Makefile.am b/gas/Makefile.am
> index bd597398671..5f0f24abf8d 100644
> --- a/gas/Makefile.am
> +++ b/gas/Makefile.am
> @@ -42,7 +42,7 @@ am__skipyacc =
>  
>  WARN_CFLAGS = @WARN_CFLAGS@ @WARN_WRITE_STRINGS@
>  NO_WERROR = @NO_WERROR@
> -AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
> +AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS)
>  
>  TARG_CPU = @target_cpu_type@
>  TARG_CPU_C = $(srcdir)/config/tc-@target_cpu_type@.c
> @@ -407,7 +407,7 @@ STAGESTUFF = *.@OBJEXT@ $(noinst_PROGRAMS)
>  
>  as_new_SOURCES = $(GAS_CFILES)
>  as_new_LDADD = $(TARG_CPU_O) $(OBJ_FORMAT_O) $(ATOF_TARG_O) \
> -	$(extra_objects) $(GASLIBS) $(LIBINTL) $(LIBM) $(ZLIB)
> +	$(extra_objects) $(GASLIBS) $(LIBINTL) $(LIBM) $(ZLIB) $(ZSTD_LIBS)
>  as_new_DEPENDENCIES = $(TARG_CPU_O) $(OBJ_FORMAT_O) $(ATOF_TARG_O) \
>  	$(extra_objects) $(GASLIBS) $(LIBINTL_DEP)
>  EXTRA_as_new_SOURCES = $(CFILES) $(HFILES) $(TARGET_CPU_CFILES) \
> diff --git a/gas/Makefile.in b/gas/Makefile.in
> index c57d78f82c4..5a4dd702252 100644
> --- a/gas/Makefile.in
> +++ b/gas/Makefile.in
> @@ -140,10 +140,12 @@ am__aclocal_m4_deps = $(top_srcdir)/../bfd/acinclude.m4 \
>  	$(top_srcdir)/../config/lead-dot.m4 \
>  	$(top_srcdir)/../config/nls.m4 \
>  	$(top_srcdir)/../config/override.m4 \
> +	$(top_srcdir)/../config/pkg.m4 \
>  	$(top_srcdir)/../config/plugins.m4 \
>  	$(top_srcdir)/../config/po.m4 \
>  	$(top_srcdir)/../config/progtest.m4 \
> -	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
> +	$(top_srcdir)/../config/zlib.m4 \
> +	$(top_srcdir)/../config/zstd.m4 $(top_srcdir)/../libtool.m4 \
>  	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
>  	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
>  	$(top_srcdir)/acinclude.m4 $(top_srcdir)/../bfd/version.m4 \
> @@ -429,6 +431,9 @@ PACKAGE_TARNAME = @PACKAGE_TARNAME@
>  PACKAGE_URL = @PACKAGE_URL@
>  PACKAGE_VERSION = @PACKAGE_VERSION@
>  PATH_SEPARATOR = @PATH_SEPARATOR@
> +PKG_CONFIG = @PKG_CONFIG@
> +PKG_CONFIG_LIBDIR = @PKG_CONFIG_LIBDIR@
> +PKG_CONFIG_PATH = @PKG_CONFIG_PATH@
>  POSUB = @POSUB@
>  RANLIB = @RANLIB@
>  SED = @SED@
> @@ -443,6 +448,8 @@ WARN_WRITE_STRINGS = @WARN_WRITE_STRINGS@
>  XGETTEXT = @XGETTEXT@
>  YACC = `if [ -f ../bison/bison ] ; then echo ../bison/bison -y -L../bison/bison ; else echo @YACC@ ; fi`
>  YFLAGS = @YFLAGS@
> +ZSTD_CFLAGS = @ZSTD_CFLAGS@
> +ZSTD_LIBS = @ZSTD_LIBS@
>  abs_builddir = @abs_builddir@
>  abs_srcdir = @abs_srcdir@
>  abs_top_builddir = @abs_top_builddir@
> @@ -524,7 +531,7 @@ ZLIBINC = @zlibinc@
>  # maintainer mode is disabled.  Avoid this.
>  am__skiplex = 
>  am__skipyacc = 
> -AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
> +AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS)
>  TARG_CPU = @target_cpu_type@
>  TARG_CPU_C = $(srcdir)/config/tc-@target_cpu_type@.c
>  TARG_CPU_O = config/tc-@target_cpu_type@.@OBJEXT@
> @@ -874,7 +881,7 @@ GASLIBS = @OPCODES_LIB@ ../bfd/libbfd.la ../libiberty/libiberty.a
>  STAGESTUFF = *.@OBJEXT@ $(noinst_PROGRAMS)
>  as_new_SOURCES = $(GAS_CFILES)
>  as_new_LDADD = $(TARG_CPU_O) $(OBJ_FORMAT_O) $(ATOF_TARG_O) \
> -	$(extra_objects) $(GASLIBS) $(LIBINTL) $(LIBM) $(ZLIB)
> +	$(extra_objects) $(GASLIBS) $(LIBINTL) $(LIBM) $(ZLIB) $(ZSTD_LIBS)
>  
>  as_new_DEPENDENCIES = $(TARG_CPU_O) $(OBJ_FORMAT_O) $(ATOF_TARG_O) \
>  	$(extra_objects) $(GASLIBS) $(LIBINTL_DEP)
> diff --git a/gas/aclocal.m4 b/gas/aclocal.m4
> index 70183124da7..722030c776f 100644
> --- a/gas/aclocal.m4
> +++ b/gas/aclocal.m4
> @@ -1196,10 +1196,12 @@ m4_include([../config/lcmessage.m4])
>  m4_include([../config/lead-dot.m4])
>  m4_include([../config/nls.m4])
>  m4_include([../config/override.m4])
> +m4_include([../config/pkg.m4])
>  m4_include([../config/plugins.m4])
>  m4_include([../config/po.m4])
>  m4_include([../config/progtest.m4])
>  m4_include([../config/zlib.m4])
> +m4_include([../config/zstd.m4])
>  m4_include([../libtool.m4])
>  m4_include([../ltoptions.m4])
>  m4_include([../ltsugar.m4])
> diff --git a/gas/as.c b/gas/as.c
> index 6268779cf90..35ad6b3ab3b 100644
> --- a/gas/as.c
> +++ b/gas/as.c
> @@ -252,14 +252,14 @@ Options:\n\
>    --alternate             initially turn on alternate macro syntax\n"));
>  #ifdef DEFAULT_FLAG_COMPRESS_DEBUG
>    fprintf (stream, _("\
> -  --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi}]\n\
> +  --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi|zstd}]\n\
>                            compress DWARF debug sections using zlib [default]\n"));
>    fprintf (stream, _("\
>    --nocompress-debug-sections\n\
>                            don't compress DWARF debug sections\n"));
>  #else
>    fprintf (stream, _("\
> -  --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi}]\n\
> +  --compress-debug-sections[={none|zlib|zlib-gnu|zlib-gabi|zstd}]\n\
>                            compress DWARF debug sections using zlib\n"));
>    fprintf (stream, _("\
>    --nocompress-debug-sections\n\
> @@ -736,6 +736,15 @@ This program has absolutely no warranty.\n"));
>  		flag_compress_debug = COMPRESS_DEBUG_GNU_ZLIB;
>  	      else if (strcasecmp (optarg, "zlib-gabi") == 0)
>  		flag_compress_debug = COMPRESS_DEBUG_GABI_ZLIB;
> +	      else if (strcasecmp (optarg, "zstd") == 0)
> +		{
> +#ifdef HAVE_ZSTD
> +		  flag_compress_debug = COMPRESS_DEBUG_ZSTD;
> +#else
> +		  as_fatal (_ ("--compress-debug-sections=zstd: gas is not "
> +			       "built with zstd support"));
> +#endif
> +		}
>  	      else
>  		as_fatal (_("Invalid --compress-debug-sections option: `%s'"),
>  			  optarg);
> diff --git a/gas/compress-debug.c b/gas/compress-debug.c
> index c80dbeec4e7..3cd175f6e57 100644
> --- a/gas/compress-debug.c
> +++ b/gas/compress-debug.c
> @@ -21,14 +21,23 @@
>  #include "config.h"
>  #include <stdio.h>
>  #include <zlib.h>
> +#if HAVE_ZSTD
> +#include <zstd.h>
> +#endif
>  #include "ansidecl.h"
>  #include "compress-debug.h"
>  
>  /* Initialize the compression engine.  */
>  
> -struct z_stream_s *
> -compress_init (void)
> +void *
> +compress_init (bool use_zstd)
>  {
> +  if (use_zstd) {
> +#if HAVE_ZSTD
> +    return ZSTD_createCCtx ();
> +#endif
> +  }
> +
>    static struct z_stream_s strm;
>  
>    strm.zalloc = NULL;
> @@ -42,22 +51,37 @@ compress_init (void)
>     from the engine goes into the current frag on the obstack.  */
>  
>  int
> -compress_data (struct z_stream_s *strm, const char **next_in,
> -	       int *avail_in, char **next_out, int *avail_out)
> +compress_data (bool use_zstd, void *ctx, const char **next_in, int *avail_in,
> +	       char **next_out, int *avail_out)
>  {
> -  int out_size = 0;
> -  int x;
> +  if (use_zstd)
> +    {
> +#if HAVE_ZSTD
> +      ZSTD_outBuffer ob = { *next_out, *avail_out, 0 };
> +      ZSTD_inBuffer ib = { *next_in, *avail_in, 0 };
> +      size_t ret = ZSTD_compressStream2 (ctx, &ob, &ib, ZSTD_e_continue);
> +      *next_in += ib.pos;
> +      *avail_in -= ib.pos;
> +      *next_out += ob.pos;
> +      *avail_out -= ob.pos;
> +      if (ZSTD_isError (ret))
> +	return -1;
> +      return (int)ob.pos;
> +#endif
> +    }
> +
> +  struct z_stream_s *strm = ctx;
>  
>    strm->next_in = (Bytef *) (*next_in);
>    strm->avail_in = *avail_in;
>    strm->next_out = (Bytef *) (*next_out);
>    strm->avail_out = *avail_out;
>  
> -  x = deflate (strm, Z_NO_FLUSH);
> +  int x = deflate (strm, Z_NO_FLUSH);
>    if (x != Z_OK)
>      return -1;
>  
> -  out_size = *avail_out - strm->avail_out;
> +  int out_size = *avail_out - strm->avail_out;
>    *next_in = (char *) (strm->next_in);
>    *avail_in = strm->avail_in;
>    *next_out = (char *) (strm->next_out);
> @@ -71,10 +95,28 @@ compress_data (struct z_stream_s *strm, const char **next_in,
>     needed.  */
>  
>  int
> -compress_finish (struct z_stream_s *strm, char **next_out,
> +compress_finish (bool use_zstd, void *ctx, char **next_out,
>  		 int *avail_out, int *out_size)
>  {
> +  if (use_zstd)
> +    {
> +#if HAVE_ZSTD
> +      ZSTD_outBuffer ob = { *next_out, *avail_out, 0 };
> +      ZSTD_inBuffer ib = { 0 };
> +      size_t ret = ZSTD_compressStream2 (ctx, &ob, &ib, ZSTD_e_end);
> +      *out_size = ob.pos;
> +      *next_out += ob.pos;
> +      *avail_out -= ob.pos;
> +      if (ZSTD_isError (ret))
> +	return -1;
> +      if (ret == 0)
> +	ZSTD_freeCCtx (ctx);
> +      return ret ? 1 : 0;
> +#endif
> +    }
> +
>    int x;
> +  struct z_stream_s *strm = ctx;
>  
>    strm->avail_in = 0;
>    strm->next_out = (Bytef *) (*next_out);
> diff --git a/gas/compress-debug.h b/gas/compress-debug.h
> index 0183e269fef..87de0f8444e 100644
> --- a/gas/compress-debug.h
> +++ b/gas/compress-debug.h
> @@ -21,19 +21,19 @@
>  #ifndef COMPRESS_DEBUG_H
>  #define COMPRESS_DEBUG_H
>  
> +#include <stdbool.h>
> +
>  struct z_stream_s;
>  
>  /* Initialize the compression engine.  */
> -extern struct z_stream_s *
> -compress_init (void);
> +extern void *compress_init (bool);
>  
>  /* Stream the contents of a frag to the compression engine.  Output
>     from the engine goes into the current frag on the obstack.  */
> -extern int
> -compress_data (struct z_stream_s *, const char **, int *, char **, int *);
> +extern int compress_data (bool, void *, const char **, int *, char **, int *);
>  
>  /* Finish the compression and consume the remaining compressed output.  */
>  extern int
> -compress_finish (struct z_stream_s *, char **, int *, int *);
> +compress_finish (bool, void *, char **, int *, int *);
>  
>  #endif /* COMPRESS_DEBUG_H */
> diff --git a/gas/config.in b/gas/config.in
> index e243fd277ee..0d1668a3eac 100644
> --- a/gas/config.in
> +++ b/gas/config.in
> @@ -134,6 +134,9 @@
>  /* Define to 1 if you have the <windows.h> header file. */
>  #undef HAVE_WINDOWS_H
>  
> +/* Define to 1 if zstd is enabled. */
> +#undef HAVE_ZSTD
> +
>  /* Using i386 COFF? */
>  #undef I386COFF
>  
> diff --git a/gas/configure b/gas/configure
> index d0449a1d7ab..1833adffaa8 100755
> --- a/gas/configure
> +++ b/gas/configure
> @@ -633,6 +633,11 @@ ac_subst_vars='am__EXEEXT_FALSE
>  am__EXEEXT_TRUE
>  LTLIBOBJS
>  LIBOBJS
> +ZSTD_LIBS
> +ZSTD_CFLAGS
> +PKG_CONFIG_LIBDIR
> +PKG_CONFIG_PATH
> +PKG_CONFIG
>  zlibinc
>  zlibdir
>  LIBM
> @@ -817,6 +822,7 @@ with_cpu
>  enable_nls
>  enable_maintainer_mode
>  with_system_zlib
> +with_zstd
>  '
>        ac_precious_vars='build_alias
>  host_alias
> @@ -828,7 +834,12 @@ LIBS
>  CPPFLAGS
>  CPP
>  YACC
> -YFLAGS'
> +YFLAGS
> +PKG_CONFIG
> +PKG_CONFIG_PATH
> +PKG_CONFIG_LIBDIR
> +ZSTD_CFLAGS
> +ZSTD_LIBS'
>  
>  
>  # Initialize some variables set by options.
> @@ -1493,6 +1504,8 @@ Optional Packages:
>    --with-cpu=CPU          default cpu variant is CPU (currently only supported
>                            on ARC)
>    --with-system-zlib      use installed libz
> +  --with-zstd             support zstd compressed debug sections
> +                          (default=auto)
>  
>  Some influential environment variables:
>    CC          C compiler command
> @@ -1509,6 +1522,13 @@ Some influential environment variables:
>    YFLAGS      The list of arguments that will be passed by default to $YACC.
>                This script will default YFLAGS to the empty string to avoid a
>                default value of `-d' given by some make applications.
> +  PKG_CONFIG  path to pkg-config utility
> +  PKG_CONFIG_PATH
> +              directories to add to pkg-config's search path
> +  PKG_CONFIG_LIBDIR
> +              path overriding pkg-config's built-in search path
> +  ZSTD_CFLAGS C compiler flags for ZSTD, overriding pkg-config
> +  ZSTD_LIBS   linker flags for ZSTD, overriding pkg-config
>  
>  Use these variables to override the choices made by `configure' or to help
>  it to find libraries and programs with nonstandard names/locations.
> @@ -10702,7 +10722,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 10705 "configure"
> +#line 10725 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -10808,7 +10828,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 10811 "configure"
> +#line 10831 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -13945,7 +13965,7 @@ $as_echo "#define USE_BINARY_FOPEN 1" >>confdefs.h
>   ;;
>  esac
>  
> -# Link in zlib if we can.  This allows us to write compressed debug sections.
> +# Link in zlib/zstd if we can.  This allows us to write compressed debug sections.
>  
>    # Use the system's zlib library.
>    zlibdir="-L\$(top_builddir)/../zlib"
> @@ -13964,6 +13984,246 @@ fi
>  
>  
>  
> +
> +
> +
> +
> +
> +
> +if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
> +	if test -n "$ac_tool_prefix"; then
> +  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
> +set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> +$as_echo_n "checking for $ac_word... " >&6; }
> +if ${ac_cv_path_PKG_CONFIG+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  case $PKG_CONFIG in
> +  [\\/]* | ?:[\\/]*)
> +  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
> +  ;;
> +  *)
> +  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> +for as_dir in $PATH
> +do
> +  IFS=$as_save_IFS
> +  test -z "$as_dir" && as_dir=.
> +    for ac_exec_ext in '' $ac_executable_extensions; do
> +  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> +    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> +    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> +    break 2
> +  fi
> +done
> +  done
> +IFS=$as_save_IFS
> +
> +  ;;
> +esac
> +fi
> +PKG_CONFIG=$ac_cv_path_PKG_CONFIG
> +if test -n "$PKG_CONFIG"; then
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
> +$as_echo "$PKG_CONFIG" >&6; }
> +else
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +fi
> +
> +
> +fi
> +if test -z "$ac_cv_path_PKG_CONFIG"; then
> +  ac_pt_PKG_CONFIG=$PKG_CONFIG
> +  # Extract the first word of "pkg-config", so it can be a program name with args.
> +set dummy pkg-config; ac_word=$2
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> +$as_echo_n "checking for $ac_word... " >&6; }
> +if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  case $ac_pt_PKG_CONFIG in
> +  [\\/]* | ?:[\\/]*)
> +  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
> +  ;;
> +  *)
> +  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> +for as_dir in $PATH
> +do
> +  IFS=$as_save_IFS
> +  test -z "$as_dir" && as_dir=.
> +    for ac_exec_ext in '' $ac_executable_extensions; do
> +  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> +    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> +    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> +    break 2
> +  fi
> +done
> +  done
> +IFS=$as_save_IFS
> +
> +  ;;
> +esac
> +fi
> +ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
> +if test -n "$ac_pt_PKG_CONFIG"; then
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
> +$as_echo "$ac_pt_PKG_CONFIG" >&6; }
> +else
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +fi
> +
> +  if test "x$ac_pt_PKG_CONFIG" = x; then
> +    PKG_CONFIG=""
> +  else
> +    case $cross_compiling:$ac_tool_warned in
> +yes:)
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
> +$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
> +ac_tool_warned=yes ;;
> +esac
> +    PKG_CONFIG=$ac_pt_PKG_CONFIG
> +  fi
> +else
> +  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
> +fi
> +
> +fi
> +if test -n "$PKG_CONFIG"; then
> +	_pkg_min_version=0.9.0
> +	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
> +$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
> +	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
> +		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +	else
> +		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +		PKG_CONFIG=""
> +	fi
> +fi
> +
> +
> +# Check whether --with-zstd was given.
> +if test "${with_zstd+set}" = set; then :
> +  withval=$with_zstd;
> +else
> +  with_zstd=auto
> +fi
> +
> +
> +if test "$with_zstd" != no; then
> +
> +pkg_failed=no
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libzstd" >&5
> +$as_echo_n "checking for libzstd... " >&6; }
> +
> +if test -n "$ZSTD_CFLAGS"; then
> +    pkg_cv_ZSTD_CFLAGS="$ZSTD_CFLAGS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_CFLAGS=`$PKG_CONFIG --cflags "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +if test -n "$ZSTD_LIBS"; then
> +    pkg_cv_ZSTD_LIBS="$ZSTD_LIBS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_LIBS=`$PKG_CONFIG --libs "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +
> +if test $pkg_failed = no; then
> +  pkg_save_LDFLAGS="$LDFLAGS"
> +  LDFLAGS="$LDFLAGS $pkg_cv_ZSTD_LIBS"
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +
> +int
> +main ()
> +{
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_link "$LINENO"; then :
> +
> +else
> +  pkg_failed=yes
> +fi
> +rm -f core conftest.err conftest.$ac_objext \
> +    conftest$ac_exeext conftest.$ac_ext
> +  LDFLAGS=$pkg_save_LDFLAGS
> +fi
> +
> +
> +
> +if test $pkg_failed = yes; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
> +        _pkg_short_errors_supported=yes
> +else
> +        _pkg_short_errors_supported=no
> +fi
> +        if test $_pkg_short_errors_supported = yes; then
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libzstd" 2>&1`
> +        else
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libzstd" 2>&1`
> +        fi
> +	# Put the nasty error message in config.log where it belongs
> +	echo "$ZSTD_PKG_ERRORS" >&5
> +
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +elif test $pkg_failed = untried; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +else
> +	ZSTD_CFLAGS=$pkg_cv_ZSTD_CFLAGS
> +	ZSTD_LIBS=$pkg_cv_ZSTD_LIBS
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +
> +
> +$as_echo "#define HAVE_ZSTD 1" >>confdefs.h
> +
> +
> +fi
> +fi
> +
> +
>  # Support for VMS timestamps via cross compile
>  
>  if test "$ac_cv_header_time_h" = yes; then
> diff --git a/gas/configure.ac b/gas/configure.ac
> index 21795a82bdd..8750ea21381 100644
> --- a/gas/configure.ac
> +++ b/gas/configure.ac
> @@ -1004,8 +1004,9 @@ AC_CHECK_DECLS([asprintf, mempcpy, stpcpy])
>  
>  BFD_BINARY_FOPEN
>  
> -# Link in zlib if we can.  This allows us to write compressed debug sections.
> +# Link in zlib/zstd if we can.  This allows us to write compressed debug sections.
>  AM_ZLIB
> +AM_ZSTD
>  
>  # Support for VMS timestamps via cross compile
>  
> diff --git a/gas/doc/as.texi b/gas/doc/as.texi
> index e915893da86..01f49434021 100644
> --- a/gas/doc/as.texi
> +++ b/gas/doc/as.texi
> @@ -711,16 +711,19 @@ given section @emph{larger} then it is not compressed.
>  @itemx --compress-debug-sections=zlib
>  @itemx --compress-debug-sections=zlib-gnu
>  @itemx --compress-debug-sections=zlib-gabi
> +@itemx --compress-debug-sections=zstd
>  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-gabi} are equivalent to
>  @option{--compress-debug-sections}.
> -@option{--compress-debug-sections=zlib-gnu} compresses DWARF debug
> -sections using zlib.  The debug sections are renamed to begin with
> -@samp{.zdebug}.  Note if compression would make a given section
> -@emph{larger} then it is not compressed nor renamed.
> +@option{--compress-debug-sections=zlib-gnu} compresses DWARF debug sections
> +using the obsoleted zlib-gnu format.  The debug sections are renamed to begin
> +with @samp{.zdebug}.
> +@option{--compress-debug-sections=zstd} compresses DWARF debug
> +sections using zstd.  Note - if compression would actually make a section
> +@emph{larger}, then it is not compressed nor renamed.
>  
>  @end ifset
>  
> diff --git a/gas/write.c b/gas/write.c
> index f76bbdb706e..0e49df7c03f 100644
> --- a/gas/write.c
> +++ b/gas/write.c
> @@ -1413,7 +1413,7 @@ write_relocs (bfd *abfd ATTRIBUTE_UNUSED, asection *sec,
>  }
>  
>  static int
> -compress_frag (struct z_stream_s *strm, const char *contents, int in_size,
> +compress_frag (bool use_zstd, void *ctx, const char *contents, int in_size,
>  	       fragS **last_newf, struct obstack *ob)
>  {
>    int out_size;
> @@ -1442,10 +1442,10 @@ compress_frag (struct z_stream_s *strm, const char *contents, int in_size,
>  	as_fatal (_("can't extend frag"));
>        next_out = obstack_next_free (ob);
>        obstack_blank_fast (ob, avail_out);
> -      out_size = compress_data (strm, &contents, &in_size,
> -				&next_out, &avail_out);
> +      out_size = compress_data (use_zstd, ctx, &contents, &in_size, &next_out,
> +				&avail_out);
>        if (out_size < 0)
> -        return -1;
> +	return -1;
>  
>        f->fr_fix += out_size;
>        total_out_size += out_size;
> @@ -1471,7 +1471,6 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
>    const char *section_name;
>    char *compressed_name;
>    char *header;
> -  struct z_stream_s *strm;
>    int x;
>    flagword flags = bfd_section_flags (sec);
>    unsigned int header_size, compression_header_size;
> @@ -1485,21 +1484,22 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
>    if (!startswith (section_name, ".debug_"))
>      return;
>  
> -  strm = compress_init ();
> -  if (strm == NULL)
> +  bool use_zstd = abfd->flags & BFD_COMPRESS_ZSTD;
> +  void *ctx = compress_init (use_zstd);
> +  if (ctx == NULL)
>      return;
>  
> -  if (flag_compress_debug == COMPRESS_DEBUG_GABI_ZLIB)
> +  if (flag_compress_debug == COMPRESS_DEBUG_GNU_ZLIB)
> +    {
> +      compression_header_size = 0;
> +      header_size = 12;
> +    }
> +  else
>      {
>        compression_header_size
>  	= bfd_get_compression_header_size (stdoutput, NULL);
>        header_size = compression_header_size;
>      }
> -  else
> -    {
> -      compression_header_size = 0;
> -      header_size = 12;
> -    }
>  
>    /* Create a new frag to contain the compression header.  */
>    first_newf = frag_alloc (ob);
> @@ -1531,7 +1531,7 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
>        gas_assert (f->fr_type == rs_fill);
>        if (f->fr_fix)
>  	{
> -	  out_size = compress_frag (strm, f->fr_literal, f->fr_fix,
> +	  out_size = compress_frag (use_zstd, ctx, f->fr_literal, f->fr_fix,
>  				    &last_newf, ob);
>  	  if (out_size < 0)
>  	    return;
> @@ -1545,8 +1545,8 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
>  	{
>  	  while (count--)
>  	    {
> -	      out_size = compress_frag (strm, fill_literal, (int) fill_size,
> -				        &last_newf, ob);
> +	      out_size = compress_frag (use_zstd, ctx, fill_literal,
> +					(int)fill_size, &last_newf, ob);
>  	      if (out_size < 0)
>  		return;
>  	      compressed_size += out_size;
> @@ -1579,7 +1579,7 @@ compress_debug (bfd *abfd, asection *sec, void *xxx ATTRIBUTE_UNUSED)
>  	as_fatal (_("can't extend frag"));
>        next_out = obstack_next_free (ob);
>        obstack_blank_fast (ob, avail_out);
> -      x = compress_finish (strm, &next_out, &avail_out, &out_size);
> +      x = compress_finish (use_zstd, ctx, &next_out, &avail_out, &out_size);
>        if (x < 0)
>  	return;
>  
> @@ -2540,6 +2540,8 @@ write_object_file (void)
>      {
>        if (flag_compress_debug == COMPRESS_DEBUG_GABI_ZLIB)
>  	stdoutput->flags |= BFD_COMPRESS | BFD_COMPRESS_GABI;
> +      else if (flag_compress_debug == COMPRESS_DEBUG_ZSTD)
> +	stdoutput->flags |= BFD_COMPRESS | BFD_COMPRESS_GABI | BFD_COMPRESS_ZSTD;
>        else
>  	stdoutput->flags |= BFD_COMPRESS;
>        bfd_map_over_sections (stdoutput, compress_debug, (char *) 0);
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 2598b81d205..c528ee5aa80 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -173,6 +173,9 @@ BFD_CFLAGS = -I$(BFD_DIR) -I$(BFD_SRC)
>  ZLIB = @zlibdir@ -lz
>  ZLIBINC = @zlibinc@
>  
> +ZSTD_CFLAGS = @ZSTD_CFLAGS@
> +ZSTD_LIBS = @ZSTD_LIBS@
> +
>  # Where is the decnumber library?  Typically in ../libdecnumber.
>  LIBDECNUMBER_DIR = ../libdecnumber
>  LIBDECNUMBER = $(LIBDECNUMBER_DIR)/libdecnumber.a
> @@ -625,7 +628,7 @@ INTERNAL_CPPFLAGS = $(CPPFLAGS) @GUILE_CPPFLAGS@ @PYTHON_CPPFLAGS@ \
>  INTERNAL_CFLAGS_BASE = \
>  	$(GLOBAL_CFLAGS) $(PROFILE_CFLAGS) \
>  	$(GDB_CFLAGS) $(OPCODES_CFLAGS) $(READLINE_CFLAGS) $(ZLIBINC) \
> -	$(BFD_CFLAGS) $(INCLUDE_CFLAGS) $(LIBDECNUMBER_CFLAGS) \
> +	$(ZSTD_CFLAGS) $(BFD_CFLAGS) $(INCLUDE_CFLAGS) $(LIBDECNUMBER_CFLAGS) \
>  	$(INTL_CFLAGS) $(INCGNU) $(INCSUPPORT) $(LIBBACKTRACE_INC) \
>  	$(ENABLE_CFLAGS) $(INTERNAL_CPPFLAGS) $(SRCHIGH_CFLAGS) \
>  	$(TOP_CFLAGS) $(PTHREAD_CFLAGS) $(DEBUGINFOD_CFLAGS)
> @@ -647,7 +650,7 @@ INTERNAL_LDFLAGS = \
>  # Libraries and corresponding dependencies for compiling gdb.
>  # XM_CLIBS, defined in *config files, have host-dependent libs.
>  # LIBIBERTY appears twice on purpose.
> -CLIBS = $(SIM) $(READLINE) $(OPCODES) $(LIBCTF) $(BFD) $(ZLIB) \
> +CLIBS = $(SIM) $(READLINE) $(OPCODES) $(LIBCTF) $(BFD) $(ZLIB) $(ZSTD_LIBS) \
>          $(LIBSUPPORT) $(INTL) $(LIBIBERTY) $(LIBDECNUMBER) \
>  	$(XM_CLIBS) $(GDBTKLIBS)  $(LIBBACKTRACE_LIB) \
>  	@LIBS@ @GUILE_LIBS@ @PYTHON_LIBS@ \
> @@ -2298,6 +2301,7 @@ aclocal_m4_deps = \
>  	../config/lcmessage.m4 \
>  	../config/codeset.m4 \
>  	../config/zlib.m4 \
> +	../config/zstd.m4 \
>  	../config/ax_pthread.m4
>  
>  $(srcdir)/aclocal.m4: @MAINTAINER_MODE_TRUE@ $(aclocal_m4_deps)
> diff --git a/gdb/acinclude.m4 b/gdb/acinclude.m4
> index 95ff2b6f35e..28846119dcb 100644
> --- a/gdb/acinclude.m4
> +++ b/gdb/acinclude.m4
> @@ -43,6 +43,7 @@ m4_include([../config/lib-link.m4])
>  m4_include([../config/iconv.m4])
>  
>  m4_include([../config/zlib.m4])
> +m4_include([../config/zstd.m4])
>  
>  m4_include([../gdbsupport/common.m4])
>  
> @@ -233,7 +234,7 @@ AC_DEFUN([GDB_AC_CHECK_BFD], [
>    # always want our bfd.
>    CFLAGS="-I${srcdir}/../include -I../bfd -I${srcdir}/../bfd $CFLAGS"
>    ZLIBDIR=`echo $zlibdir | sed 's,\$(top_builddir)/,,g'`
> -  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
> +  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $ZSTD_LIBS $LDFLAGS"
>    intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
>    LIBS="-lbfd -liberty -lz $intl $LIBS"
>    AC_CACHE_CHECK(
> diff --git a/gdb/config.in b/gdb/config.in
> index a4975c68aad..e13a409ec2d 100644
> --- a/gdb/config.in
> +++ b/gdb/config.in
> @@ -589,6 +589,9 @@
>  /* Define to 1 if you have the `XML_StopParser' function. */
>  #undef HAVE_XML_STOPPARSER
>  
> +/* Define to 1 if zstd is enabled. */
> +#undef HAVE_ZSTD
> +
>  /* Define to 1 if your system has the _etext variable. */
>  #undef HAVE__ETEXT
>  
> diff --git a/gdb/configure b/gdb/configure
> index 4dbd0c3b13c..57cd165088a 100755
> --- a/gdb/configure
> +++ b/gdb/configure
> @@ -747,6 +747,8 @@ READLINE_DEPS
>  READLINE
>  LTLIBICONV
>  LIBICONV
> +ZSTD_LIBS
> +ZSTD_CFLAGS
>  zlibinc
>  zlibdir
>  MIG
> @@ -893,6 +895,7 @@ enable_codesign
>  with_pkgversion
>  with_bugurl
>  with_system_zlib
> +with_zstd
>  with_gnu_ld
>  enable_rpath
>  with_libiconv_prefix
> @@ -961,6 +964,8 @@ DEBUGINFOD_CFLAGS
>  DEBUGINFOD_LIBS
>  YACC
>  YFLAGS
> +ZSTD_CFLAGS
> +ZSTD_LIBS
>  XMKMF'
>  ac_subdirs_all='testsuite
>  gdbtk'
> @@ -1641,6 +1646,8 @@ Optional Packages:
>    --with-pkgversion=PKG   Use PKG in the version string in place of "GDB"
>    --with-bugurl=URL       Direct users to URL to report a bug
>    --with-system-zlib      use installed libz
> +  --with-zstd             support zstd compressed debug sections
> +                          (default=auto)
>    --with-gnu-ld           assume the C compiler uses GNU ld default=no
>    --with-libiconv-prefix[=DIR]  search for libiconv in DIR/include and DIR/lib
>    --without-libiconv-prefix     don't search for libiconv in includedir and libdir
> @@ -1721,6 +1728,8 @@ Some influential environment variables:
>    YFLAGS      The list of arguments that will be passed by default to $YACC.
>                This script will default YFLAGS to the empty string to avoid a
>                default value of `-d' given by some make applications.
> +  ZSTD_CFLAGS C compiler flags for ZSTD, overriding pkg-config
> +  ZSTD_LIBS   linker flags for ZSTD, overriding pkg-config
>    XMKMF       Path to xmkmf, Makefile generator for X Window System
>  
>  Use these variables to override the choices made by `configure' or to help
> @@ -8242,7 +8251,8 @@ if test "$ac_res" != no; then :
>  fi
>  
>  
> -# Link in zlib if we can.  This allows us to read compressed debug sections.
> +# Link in zlib/zstd if we can.  This allows us to read compressed debug
> +# sections.
>  
>    # Use the system's zlib library.
>    zlibdir="-L\$(top_builddir)/../zlib"
> @@ -8262,6 +8272,126 @@ fi
>  
>  
>  
> +# Check whether --with-zstd was given.
> +if test "${with_zstd+set}" = set; then :
> +  withval=$with_zstd;
> +else
> +  with_zstd=auto
> +fi
> +
> +
> +if test "$with_zstd" != no; then
> +
> +pkg_failed=no
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libzstd" >&5
> +$as_echo_n "checking for libzstd... " >&6; }
> +
> +if test -n "$ZSTD_CFLAGS"; then
> +    pkg_cv_ZSTD_CFLAGS="$ZSTD_CFLAGS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_CFLAGS=`$PKG_CONFIG --cflags "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +if test -n "$ZSTD_LIBS"; then
> +    pkg_cv_ZSTD_LIBS="$ZSTD_LIBS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_LIBS=`$PKG_CONFIG --libs "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +
> +if test $pkg_failed = no; then
> +  pkg_save_LDFLAGS="$LDFLAGS"
> +  LDFLAGS="$LDFLAGS $pkg_cv_ZSTD_LIBS"
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +
> +int
> +main ()
> +{
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_link "$LINENO"; then :
> +
> +else
> +  pkg_failed=yes
> +fi
> +rm -f core conftest.err conftest.$ac_objext \
> +    conftest$ac_exeext conftest.$ac_ext
> +  LDFLAGS=$pkg_save_LDFLAGS
> +fi
> +
> +
> +
> +if test $pkg_failed = yes; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
> +        _pkg_short_errors_supported=yes
> +else
> +        _pkg_short_errors_supported=no
> +fi
> +        if test $_pkg_short_errors_supported = yes; then
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libzstd" 2>&1`
> +        else
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libzstd" 2>&1`
> +        fi
> +	# Put the nasty error message in config.log where it belongs
> +	echo "$ZSTD_PKG_ERRORS" >&5
> +
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +elif test $pkg_failed = untried; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +else
> +	ZSTD_CFLAGS=$pkg_cv_ZSTD_CFLAGS
> +	ZSTD_LIBS=$pkg_cv_ZSTD_LIBS
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +
> +
> +$as_echo "#define HAVE_ZSTD 1" >>confdefs.h
> +
> +
> +fi
> +fi
> +
> +
> +
>        if test "X$prefix" = "XNONE"; then
>      acl_final_prefix="$ac_default_prefix"
>    else
> @@ -17281,7 +17411,7 @@ WIN32LIBS="$WIN32LIBS $WIN32APILIBS"
>    # always want our bfd.
>    CFLAGS="-I${srcdir}/../include -I../bfd -I${srcdir}/../bfd $CFLAGS"
>    ZLIBDIR=`echo $zlibdir | sed 's,\$(top_builddir)/,,g'`
> -  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
> +  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $ZSTD_LIBS $LDFLAGS"
>    intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
>    LIBS="-lbfd -liberty -lz $intl $LIBS"
>    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for ELF support in BFD" >&5
> @@ -17396,7 +17526,7 @@ fi
>    # always want our bfd.
>    CFLAGS="-I${srcdir}/../include -I../bfd -I${srcdir}/../bfd $CFLAGS"
>    ZLIBDIR=`echo $zlibdir | sed 's,\$(top_builddir)/,,g'`
> -  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $LDFLAGS"
> +  LDFLAGS="-L../bfd -L../libiberty $ZLIBDIR $ZSTD_LIBS $LDFLAGS"
>    intl=`echo $LIBINTL | sed 's,${top_builddir}/,,g'`
>    LIBS="-lbfd -liberty -lz $intl $LIBS"
>    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for Mach-O support in BFD" >&5
> diff --git a/gdb/configure.ac b/gdb/configure.ac
> index 215a91c5b27..e8cf808d280 100644
> --- a/gdb/configure.ac
> +++ b/gdb/configure.ac
> @@ -460,8 +460,10 @@ AC_SEARCH_LIBS(gethostbyname, nsl)
>  # Some systems (e.g. Solaris) have `socketpair' in libsocket.
>  AC_SEARCH_LIBS(socketpair, socket)
>  
> -# Link in zlib if we can.  This allows us to read compressed debug sections.
> +# Link in zlib/zstd if we can.  This allows us to read compressed debug
> +# sections.
>  AM_ZLIB
> +AM_ZSTD
>  
>  AM_ICONV
>  
> diff --git a/ld/Makefile.am b/ld/Makefile.am
> index d31021c13e2..bbe25f3aca2 100644
> --- a/ld/Makefile.am
> +++ b/ld/Makefile.am
> @@ -45,7 +45,7 @@ ELF_CLFAGS=-DELF_LIST_OPTIONS=@elf_list_options@ \
>  	   -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@
>  WARN_CFLAGS = @WARN_CFLAGS@
>  NO_WERROR = @NO_WERROR@
> -AM_CFLAGS = $(WARN_CFLAGS) $(ELF_CLFAGS) $(JANSSON_CFLAGS)
> +AM_CFLAGS = $(WARN_CFLAGS) $(ELF_CLFAGS) $(JANSSON_CFLAGS) $(ZSTD_CFLAGS)
>  
>  # We put the scripts in the directory $(scriptdir)/ldscripts.
>  # We can't put the scripts in $(datadir) because the SEARCH_DIR
> @@ -959,7 +959,8 @@ ld_new_SOURCES = ldgram.y ldlex-wrapper.c lexsup.c ldlang.c mri.c ldctor.c ldmai
>  	ldbuildid.c
>  ld_new_DEPENDENCIES = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) \
>  		      $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL_DEP) $(JANSSON_LIBS)
> -ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL) $(ZLIB) $(JANSSON_LIBS)
> +ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBCTF) \
> +	       $(LIBIBERTY) $(LIBINTL) $(ZLIB) $(ZSTD_LIBS) $(JANSSON_LIBS)
>  
>  # Dependency tracking for the generated emulation files.
>  EXTRA_ld_new_SOURCES += $(ALL_EMULATION_SOURCES) $(ALL_64_EMULATION_SOURCES)
> diff --git a/ld/Makefile.in b/ld/Makefile.in
> index ee0c98f65b0..400eed2717e 100644
> --- a/ld/Makefile.in
> +++ b/ld/Makefile.in
> @@ -126,7 +126,8 @@ am__aclocal_m4_deps = $(top_srcdir)/../bfd/acinclude.m4 \
>  	$(top_srcdir)/../config/plugins.m4 \
>  	$(top_srcdir)/../config/po.m4 \
>  	$(top_srcdir)/../config/progtest.m4 \
> -	$(top_srcdir)/../config/zlib.m4 $(top_srcdir)/../libtool.m4 \
> +	$(top_srcdir)/../config/zlib.m4 \
> +	$(top_srcdir)/../config/zstd.m4 $(top_srcdir)/../libtool.m4 \
>  	$(top_srcdir)/../ltoptions.m4 $(top_srcdir)/../ltsugar.m4 \
>  	$(top_srcdir)/../ltversion.m4 $(top_srcdir)/../lt~obsolete.m4 \
>  	$(top_srcdir)/../bfd/version.m4 $(top_srcdir)/configure.ac
> @@ -477,6 +478,8 @@ WARN_WRITE_STRINGS = @WARN_WRITE_STRINGS@
>  XGETTEXT = @XGETTEXT@
>  YACC = `if [ -f ../bison/bison ]; then echo ../bison/bison -y -L$(srcdir)/../bison/; else echo @YACC@; fi`
>  YFLAGS = -d
> +ZSTD_CFLAGS = @ZSTD_CFLAGS@
> +ZSTD_LIBS = @ZSTD_LIBS@
>  abs_builddir = @abs_builddir@
>  abs_srcdir = @abs_srcdir@
>  abs_top_builddir = @abs_top_builddir@
> @@ -564,7 +567,7 @@ ELF_CLFAGS = -DELF_LIST_OPTIONS=@elf_list_options@ \
>  	   -DELF_SHLIB_LIST_OPTIONS=@elf_shlib_list_options@ \
>  	   -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@
>  
> -AM_CFLAGS = $(WARN_CFLAGS) $(ELF_CLFAGS) $(JANSSON_CFLAGS)
> +AM_CFLAGS = $(WARN_CFLAGS) $(ELF_CLFAGS) $(JANSSON_CFLAGS) $(ZSTD_CFLAGS)
>  
>  # We put the scripts in the directory $(scriptdir)/ldscripts.
>  # We can't put the scripts in $(datadir) because the SEARCH_DIR
> @@ -1011,7 +1014,9 @@ ld_new_SOURCES = ldgram.y ldlex-wrapper.c lexsup.c ldlang.c mri.c ldctor.c ldmai
>  ld_new_DEPENDENCIES = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) \
>  		      $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL_DEP) $(JANSSON_LIBS)
>  
> -ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBCTF) $(LIBIBERTY) $(LIBINTL) $(ZLIB) $(JANSSON_LIBS)
> +ld_new_LDADD = $(EMULATION_OFILES) $(EMUL_EXTRA_OFILES) $(BFDLIB) $(LIBCTF) \
> +	       $(LIBIBERTY) $(LIBINTL) $(ZLIB) $(ZSTD_LIBS) $(JANSSON_LIBS)
> +
>  #
>  #
>  # Build a dummy plugin using libtool.
> diff --git a/ld/aclocal.m4 b/ld/aclocal.m4
> index d20c542eed5..893e973e4f2 100644
> --- a/ld/aclocal.m4
> +++ b/ld/aclocal.m4
> @@ -1203,6 +1203,7 @@ m4_include([../config/plugins.m4])
>  m4_include([../config/po.m4])
>  m4_include([../config/progtest.m4])
>  m4_include([../config/zlib.m4])
> +m4_include([../config/zstd.m4])
>  m4_include([../libtool.m4])
>  m4_include([../ltoptions.m4])
>  m4_include([../ltsugar.m4])
> diff --git a/ld/config.in b/ld/config.in
> index 0ccd79d59cd..3916740eee4 100644
> --- a/ld/config.in
> +++ b/ld/config.in
> @@ -162,6 +162,9 @@
>  /* Define to 1 if you have the <windows.h> header file. */
>  #undef HAVE_WINDOWS_H
>  
> +/* Define to 1 if zstd is enabled. */
> +#undef HAVE_ZSTD
> +
>  /* Define to the sub-directory in which libtool stores uninstalled libraries.
>     */
>  #undef LT_OBJDIR
> diff --git a/ld/configure b/ld/configure
> index a1a07005400..175dd995b2b 100755
> --- a/ld/configure
> +++ b/ld/configure
> @@ -646,6 +646,8 @@ elf_plt_unwind_list_options
>  elf_shlib_list_options
>  elf_list_options
>  STRINGIFY
> +ZSTD_LIBS
> +ZSTD_CFLAGS
>  zlibinc
>  zlibdir
>  NATIVE_LIB_DIRS
> @@ -679,9 +681,6 @@ WARN_CFLAGS_FOR_BUILD
>  WARN_CFLAGS
>  JANSSON_LIBS
>  JANSSON_CFLAGS
> -PKG_CONFIG_LIBDIR
> -PKG_CONFIG_PATH
> -PKG_CONFIG
>  enable_libctf
>  ENABLE_LIBCTF_FALSE
>  ENABLE_LIBCTF_TRUE
> @@ -711,6 +710,9 @@ LD
>  FGREP
>  SED
>  LIBTOOL
> +PKG_CONFIG_LIBDIR
> +PKG_CONFIG_PATH
> +PKG_CONFIG
>  EGREP
>  CPP
>  GREP
> @@ -855,6 +857,7 @@ enable_werror
>  enable_build_warnings
>  enable_nls
>  with_system_zlib
> +with_zstd
>  '
>        ac_precious_vars='build_alias
>  host_alias
> @@ -868,14 +871,16 @@ CXX
>  CXXFLAGS
>  CCC
>  CPP
> -CXXCPP
>  PKG_CONFIG
>  PKG_CONFIG_PATH
>  PKG_CONFIG_LIBDIR
> +CXXCPP
>  JANSSON_CFLAGS
>  JANSSON_LIBS
>  YACC
> -YFLAGS'
> +YFLAGS
> +ZSTD_CFLAGS
> +ZSTD_LIBS'
>  
>  
>  # Initialize some variables set by options.
> @@ -1552,6 +1557,8 @@ Optional Packages:
>    --with-lib-path=dir1:dir2...  set default LIB_PATH
>    --with-sysroot=DIR Search for usr/lib et al within DIR.
>    --with-system-zlib      use installed libz
> +  --with-zstd             support zstd compressed debug sections
> +                          (default=auto)
>  
>  Some influential environment variables:
>    CC          C compiler command
> @@ -1564,12 +1571,12 @@ Some influential environment variables:
>    CXX         C++ compiler command
>    CXXFLAGS    C++ compiler flags
>    CPP         C preprocessor
> -  CXXCPP      C++ preprocessor
>    PKG_CONFIG  path to pkg-config utility
>    PKG_CONFIG_PATH
>                directories to add to pkg-config's search path
>    PKG_CONFIG_LIBDIR
>                path overriding pkg-config's built-in search path
> +  CXXCPP      C++ preprocessor
>    JANSSON_CFLAGS
>                C compiler flags for JANSSON, overriding pkg-config
>    JANSSON_LIBS
> @@ -1580,6 +1587,8 @@ Some influential environment variables:
>    YFLAGS      The list of arguments that will be passed by default to $YACC.
>                This script will default YFLAGS to the empty string to avoid a
>                default value of `-d' given by some make applications.
> +  ZSTD_CFLAGS C compiler flags for ZSTD, overriding pkg-config
> +  ZSTD_LIBS   linker flags for ZSTD, overriding pkg-config
>  
>  Use these variables to override the choices made by `configure' or to help
>  it to find libraries and programs with nonstandard names/locations.
> @@ -5388,6 +5397,126 @@ $as_echo "$ac_cv_safe_to_define___extensions__" >&6; }
>  
>  
>  
> +
> +
> +
> +
> +
> +
> +if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
> +	if test -n "$ac_tool_prefix"; then
> +  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
> +set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> +$as_echo_n "checking for $ac_word... " >&6; }
> +if ${ac_cv_path_PKG_CONFIG+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  case $PKG_CONFIG in
> +  [\\/]* | ?:[\\/]*)
> +  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
> +  ;;
> +  *)
> +  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> +for as_dir in $PATH
> +do
> +  IFS=$as_save_IFS
> +  test -z "$as_dir" && as_dir=.
> +    for ac_exec_ext in '' $ac_executable_extensions; do
> +  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> +    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> +    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> +    break 2
> +  fi
> +done
> +  done
> +IFS=$as_save_IFS
> +
> +  ;;
> +esac
> +fi
> +PKG_CONFIG=$ac_cv_path_PKG_CONFIG
> +if test -n "$PKG_CONFIG"; then
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
> +$as_echo "$PKG_CONFIG" >&6; }
> +else
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +fi
> +
> +
> +fi
> +if test -z "$ac_cv_path_PKG_CONFIG"; then
> +  ac_pt_PKG_CONFIG=$PKG_CONFIG
> +  # Extract the first word of "pkg-config", so it can be a program name with args.
> +set dummy pkg-config; ac_word=$2
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> +$as_echo_n "checking for $ac_word... " >&6; }
> +if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  case $ac_pt_PKG_CONFIG in
> +  [\\/]* | ?:[\\/]*)
> +  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
> +  ;;
> +  *)
> +  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> +for as_dir in $PATH
> +do
> +  IFS=$as_save_IFS
> +  test -z "$as_dir" && as_dir=.
> +    for ac_exec_ext in '' $ac_executable_extensions; do
> +  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> +    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> +    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> +    break 2
> +  fi
> +done
> +  done
> +IFS=$as_save_IFS
> +
> +  ;;
> +esac
> +fi
> +ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
> +if test -n "$ac_pt_PKG_CONFIG"; then
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
> +$as_echo "$ac_pt_PKG_CONFIG" >&6; }
> +else
> +  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +fi
> +
> +  if test "x$ac_pt_PKG_CONFIG" = x; then
> +    PKG_CONFIG=""
> +  else
> +    case $cross_compiling:$ac_tool_warned in
> +yes:)
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
> +$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
> +ac_tool_warned=yes ;;
> +esac
> +    PKG_CONFIG=$ac_pt_PKG_CONFIG
> +  fi
> +else
> +  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
> +fi
> +
> +fi
> +if test -n "$PKG_CONFIG"; then
> +	_pkg_min_version=0.9.0
> +	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
> +$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
> +	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
> +		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +	else
> +		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +		PKG_CONFIG=""
> +	fi
> +fi
> +
>  case `pwd` in
>    *\ * | *\	*)
>      { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: Libtool does not cope well with whitespace in \`pwd\`" >&5
> @@ -11491,7 +11620,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 11494 "configure"
> +#line 11623 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -11597,7 +11726,7 @@ else
>    lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
>    lt_status=$lt_dlunknown
>    cat > conftest.$ac_ext <<_LT_EOF
> -#line 11600 "configure"
> +#line 11729 "configure"
>  #include "confdefs.h"
>  
>  #if HAVE_DLFCN_H
> @@ -15586,126 +15715,6 @@ fi
>  
>  
>  if test "x$enable_jansson" != "xno"; then
> -
> -
> -
> -
> -
> -
> -
> -if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
> -	if test -n "$ac_tool_prefix"; then
> -  # Extract the first word of "${ac_tool_prefix}pkg-config", so it can be a program name with args.
> -set dummy ${ac_tool_prefix}pkg-config; ac_word=$2
> -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> -$as_echo_n "checking for $ac_word... " >&6; }
> -if ${ac_cv_path_PKG_CONFIG+:} false; then :
> -  $as_echo_n "(cached) " >&6
> -else
> -  case $PKG_CONFIG in
> -  [\\/]* | ?:[\\/]*)
> -  ac_cv_path_PKG_CONFIG="$PKG_CONFIG" # Let the user override the test with a path.
> -  ;;
> -  *)
> -  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> -for as_dir in $PATH
> -do
> -  IFS=$as_save_IFS
> -  test -z "$as_dir" && as_dir=.
> -    for ac_exec_ext in '' $ac_executable_extensions; do
> -  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> -    ac_cv_path_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> -    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> -    break 2
> -  fi
> -done
> -  done
> -IFS=$as_save_IFS
> -
> -  ;;
> -esac
> -fi
> -PKG_CONFIG=$ac_cv_path_PKG_CONFIG
> -if test -n "$PKG_CONFIG"; then
> -  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $PKG_CONFIG" >&5
> -$as_echo "$PKG_CONFIG" >&6; }
> -else
> -  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> -$as_echo "no" >&6; }
> -fi
> -
> -
> -fi
> -if test -z "$ac_cv_path_PKG_CONFIG"; then
> -  ac_pt_PKG_CONFIG=$PKG_CONFIG
> -  # Extract the first word of "pkg-config", so it can be a program name with args.
> -set dummy pkg-config; ac_word=$2
> -{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
> -$as_echo_n "checking for $ac_word... " >&6; }
> -if ${ac_cv_path_ac_pt_PKG_CONFIG+:} false; then :
> -  $as_echo_n "(cached) " >&6
> -else
> -  case $ac_pt_PKG_CONFIG in
> -  [\\/]* | ?:[\\/]*)
> -  ac_cv_path_ac_pt_PKG_CONFIG="$ac_pt_PKG_CONFIG" # Let the user override the test with a path.
> -  ;;
> -  *)
> -  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
> -for as_dir in $PATH
> -do
> -  IFS=$as_save_IFS
> -  test -z "$as_dir" && as_dir=.
> -    for ac_exec_ext in '' $ac_executable_extensions; do
> -  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
> -    ac_cv_path_ac_pt_PKG_CONFIG="$as_dir/$ac_word$ac_exec_ext"
> -    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
> -    break 2
> -  fi
> -done
> -  done
> -IFS=$as_save_IFS
> -
> -  ;;
> -esac
> -fi
> -ac_pt_PKG_CONFIG=$ac_cv_path_ac_pt_PKG_CONFIG
> -if test -n "$ac_pt_PKG_CONFIG"; then
> -  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_pt_PKG_CONFIG" >&5
> -$as_echo "$ac_pt_PKG_CONFIG" >&6; }
> -else
> -  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> -$as_echo "no" >&6; }
> -fi
> -
> -  if test "x$ac_pt_PKG_CONFIG" = x; then
> -    PKG_CONFIG=""
> -  else
> -    case $cross_compiling:$ac_tool_warned in
> -yes:)
> -{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
> -$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
> -ac_tool_warned=yes ;;
> -esac
> -    PKG_CONFIG=$ac_pt_PKG_CONFIG
> -  fi
> -else
> -  PKG_CONFIG="$ac_cv_path_PKG_CONFIG"
> -fi
> -
> -fi
> -if test -n "$PKG_CONFIG"; then
> -	_pkg_min_version=0.9.0
> -	{ $as_echo "$as_me:${as_lineno-$LINENO}: checking pkg-config is at least version $_pkg_min_version" >&5
> -$as_echo_n "checking pkg-config is at least version $_pkg_min_version... " >&6; }
> -	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
> -		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> -$as_echo "yes" >&6; }
> -	else
> -		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> -$as_echo "no" >&6; }
> -		PKG_CONFIG=""
> -	fi
> -fi
>    if test -n "$PKG_CONFIG"; then :
>  
>  
> @@ -17052,8 +17061,8 @@ $as_echo "#define HAVE_DECL_GETOPT 1" >>confdefs.h
>  
>  fi
>  
> -# Link in zlib if we can.  This allows us to read and write
> -# compressed CTF sections.
> +# Link in zlib/zstd if we can.  This allows us to read and write
> +# compressed debug sections.
>  
>    # Use the system's zlib library.
>    zlibdir="-L\$(top_builddir)/../zlib"
> @@ -17072,6 +17081,126 @@ fi
>  
>  
>  
> +
> +# Check whether --with-zstd was given.
> +if test "${with_zstd+set}" = set; then :
> +  withval=$with_zstd;
> +else
> +  with_zstd=auto
> +fi
> +
> +
> +if test "$with_zstd" != no; then
> +
> +pkg_failed=no
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libzstd" >&5
> +$as_echo_n "checking for libzstd... " >&6; }
> +
> +if test -n "$ZSTD_CFLAGS"; then
> +    pkg_cv_ZSTD_CFLAGS="$ZSTD_CFLAGS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_CFLAGS=`$PKG_CONFIG --cflags "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +if test -n "$ZSTD_LIBS"; then
> +    pkg_cv_ZSTD_LIBS="$ZSTD_LIBS"
> + elif test -n "$PKG_CONFIG"; then
> +    if test -n "$PKG_CONFIG" && \
> +    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libzstd\""; } >&5
> +  ($PKG_CONFIG --exists --print-errors "libzstd") 2>&5
> +  ac_status=$?
> +  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
> +  test $ac_status = 0; }; then
> +  pkg_cv_ZSTD_LIBS=`$PKG_CONFIG --libs "libzstd" 2>/dev/null`
> +		      test "x$?" != "x0" && pkg_failed=yes
> +else
> +  pkg_failed=yes
> +fi
> + else
> +    pkg_failed=untried
> +fi
> +
> +if test $pkg_failed = no; then
> +  pkg_save_LDFLAGS="$LDFLAGS"
> +  LDFLAGS="$LDFLAGS $pkg_cv_ZSTD_LIBS"
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +
> +int
> +main ()
> +{
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_link "$LINENO"; then :
> +
> +else
> +  pkg_failed=yes
> +fi
> +rm -f core conftest.err conftest.$ac_objext \
> +    conftest$ac_exeext conftest.$ac_ext
> +  LDFLAGS=$pkg_save_LDFLAGS
> +fi
> +
> +
> +
> +if test $pkg_failed = yes; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
> +        _pkg_short_errors_supported=yes
> +else
> +        _pkg_short_errors_supported=no
> +fi
> +        if test $_pkg_short_errors_supported = yes; then
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libzstd" 2>&1`
> +        else
> +	        ZSTD_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libzstd" 2>&1`
> +        fi
> +	# Put the nasty error message in config.log where it belongs
> +	echo "$ZSTD_PKG_ERRORS" >&5
> +
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +elif test $pkg_failed = untried; then
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
> +$as_echo "no" >&6; }
> +
> +    if test "$with_zstd" = yes; then
> +      as_fn_error $? "--with-zstd was given, but pkgconfig/libzstd.pc is not found" "$LINENO" 5
> +    fi
> +
> +else
> +	ZSTD_CFLAGS=$pkg_cv_ZSTD_CFLAGS
> +	ZSTD_LIBS=$pkg_cv_ZSTD_LIBS
> +        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
> +$as_echo "yes" >&6; }
> +
> +
> +$as_echo "#define HAVE_ZSTD 1" >>confdefs.h
> +
> +
> +fi
> +fi
> +
> +
>  # When converting linker scripts into strings for use in emulation
>  # files, use astring.sed if the compiler supports ANSI string
>  # concatenation, or ostring.sed otherwise.  This is to support the
> diff --git a/ld/configure.ac b/ld/configure.ac
> index eb55904c090..a491f9f1116 100644
> --- a/ld/configure.ac
> +++ b/ld/configure.ac
> @@ -34,6 +34,7 @@ AC_PROG_GREP
>  AC_GNU_SOURCE
>  AC_USE_SYSTEM_EXTENSIONS
>  AC_PROG_INSTALL
> +PKG_PROG_PKG_CONFIG
>  
>  LT_INIT
>  ACX_LARGEFILE
> @@ -297,7 +298,6 @@ AC_ARG_ENABLE([jansson],
>    [enable_jansson="no"])
>  
>  if test "x$enable_jansson" != "xno"; then
> -  PKG_PROG_PKG_CONFIG
>    AS_IF([test -n "$PKG_CONFIG"],
>      [
>        PKG_CHECK_MODULES(JANSSON, [jansson],
> @@ -386,9 +386,10 @@ if test $ld_cv_decl_getopt_unistd_h = yes; then
>  	    [Is the prototype for getopt in <unistd.h> in the expected format?])
>  fi
>  
> -# Link in zlib if we can.  This allows us to read and write
> -# compressed CTF sections.
> +# Link in zlib/zstd if we can.  This allows us to read and write
> +# compressed debug sections.
>  AM_ZLIB
> +AM_ZSTD
>  
>  # When converting linker scripts into strings for use in emulation
>  # files, use astring.sed if the compiler supports ANSI string
> diff --git a/ld/emultempl/elf.em b/ld/emultempl/elf.em
> index c52484f35d3..acd66f907d1 100644
> --- a/ld/emultempl/elf.em
> +++ b/ld/emultempl/elf.em
> @@ -668,6 +668,15 @@ gld${EMULATION_NAME}_handle_option (int optc)
>  	link_info.compress_debug = COMPRESS_DEBUG_GNU_ZLIB;
>        else if (strcasecmp (optarg, "zlib-gabi") == 0)
>  	link_info.compress_debug = COMPRESS_DEBUG_GABI_ZLIB;
> +      else if (strcasecmp (optarg, "zstd") == 0)
> +	{
> +#ifdef HAVE_ZSTD
> +	  link_info.compress_debug = COMPRESS_DEBUG_ZSTD;
> +#else
> +	  einfo (_ ("%F%P: --compress-debug-sections=zstd: ld is not built "
> +		    "with zstd support\n"));
> +#endif
> +	}
>        else
>  	einfo (_("%F%P: invalid --compress-debug-sections option: \`%s'\n"),
>  	       optarg);
> diff --git a/ld/ld.texi b/ld/ld.texi
> index eabbec8faa9..9daed2e7e9f 100644
> --- a/ld/ld.texi
> +++ b/ld/ld.texi
> @@ -2863,10 +2863,12 @@ but for most Linux based systems it will be @code{both}.
>  @kindex --compress-debug-sections=zlib
>  @kindex --compress-debug-sections=zlib-gnu
>  @kindex --compress-debug-sections=zlib-gabi
> +@kindex --compress-debug-sections=zstd
>  @item --compress-debug-sections=none
>  @itemx --compress-debug-sections=zlib
>  @itemx --compress-debug-sections=zlib-gnu
>  @itemx --compress-debug-sections=zlib-gabi
> +@itemx --compress-debug-sections=zstd
>  On ELF platforms, these options control how DWARF debug sections are
>  compressed using zlib.
>  
> @@ -2880,6 +2882,9 @@ sets the SHF_COMPRESSED flag in the sections' headers.
>  The @option{--compress-debug-sections=zlib} option is an alias for
>  @option{--compress-debug-sections=zlib-gabi}.
>  
> +@option{--compress-debug-sections=zstd} compresses DWARF debug sections using
> +zstd.
> +
>  Note that this option overrides any compression in input debug
>  sections, so if a binary is linked with @option{--compress-debug-sections=none}
>  for example, then any compressed debug sections in input files will be
> diff --git a/ld/ldmain.c b/ld/ldmain.c
> index 1bbddaaad32..71af5935b74 100644
> --- a/ld/ldmain.c
> +++ b/ld/ldmain.c
> @@ -506,8 +506,12 @@ main (int argc, char **argv)
>    if ((link_info.compress_debug & COMPRESS_DEBUG))
>      {
>        link_info.output_bfd->flags |= BFD_COMPRESS;
> -      if (link_info.compress_debug == COMPRESS_DEBUG_GABI_ZLIB)
> -	link_info.output_bfd->flags |= BFD_COMPRESS_GABI;
> +      if (link_info.compress_debug != COMPRESS_DEBUG_GNU_ZLIB)
> +	{
> +	  link_info.output_bfd->flags |= BFD_COMPRESS_GABI;
> +	  if (link_info.compress_debug == COMPRESS_DEBUG_ZSTD)
> +	    link_info.output_bfd->flags |= BFD_COMPRESS_ZSTD;
> +	}
>      }
>  
>    ldwrite ();
> diff --git a/ld/lexsup.c b/ld/lexsup.c
> index 9225f71b3ce..299371fb775 100644
> --- a/ld/lexsup.c
> +++ b/ld/lexsup.c
> @@ -2146,8 +2146,8 @@ elf_static_list_options (FILE *file)
>    fprintf (file, _("\
>    --package-metadata[=JSON]   Generate package metadata note\n"));
>    fprintf (file, _("\
> -  --compress-debug-sections=[none|zlib|zlib-gnu|zlib-gabi]\n\
> -                              Compress DWARF debug sections using zlib\n"));
> +  --compress-debug-sections=[none|zlib|zlib-gnu|zlib-gabi|zstd]\n\
> +			      Compress DWARF debug sections\n"));
>  #ifdef DEFAULT_FLAG_COMPRESS_DEBUG
>    fprintf (file, _("\
>                                  Default: zlib-gabi\n"));
> diff --git a/ld/testsuite/ld-elf/compress.exp b/ld/testsuite/ld-elf/compress.exp
> index cfdd767b8ab..7b8a31cc41d 100644
> --- a/ld/testsuite/ld-elf/compress.exp
> +++ b/ld/testsuite/ld-elf/compress.exp
> @@ -254,3 +254,20 @@ if { [regexp_diff tmpdir/$test.out $srcdir/$subdir/$test.rt] } then {
>  } else {
>      pass "$test_name"
>  }
> +
> +if { ![ld_assemble $as "--compress-debug-sections=zstd $srcdir/$subdir/empty.s" tmpdir/emptyzstd.o ] } {
> +    return
> +}
> +set build_tests {
> +  {"Build libzstdfoo.so with zstd compressed debug sections"
> +   "-shared" "-fPIC -g -Wa,--compress-debug-sections=zstd -Wl,--compress-debug-sections=zstd"
> +   {foo.c} {} "libzstdfoo.so"}
> +}
> +set run_tests {
> +    {"Run zstdnormal with libzstdfoo.so with zstd compressed debug sections"
> +     "tmpdir/begin.o tmpdir/libzstdfoo.so tmpdir/end.o -Wl,--compress-debug-sections=zstd" ""
> +     {main.c} "zstdnormal" "normal.out" "-Wa,--compress-debug-sections=zstd"}
> +}
> +
> +run_cc_link_tests $build_tests
> +run_ld_link_exec_tests $run_tests

  parent reply	other threads:[~2022-09-24  6:53 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-23  4:08 Fangrui Song
2022-09-23 14:32 ` Simon Marchi
2022-09-26  5:12   ` Alan Modra
2022-09-26  7:20     ` Fangrui Song
2022-09-26 13:30       ` Alan Modra
2022-09-26 14:08     ` Simon Marchi
2022-09-27  0:33       ` Alan Modra
2022-09-23 15:45 ` Nick Clifton
2022-09-23 15:58   ` Simon Marchi
2022-09-23 18:20     ` Fangrui Song
2022-09-23 18:57       ` Simon Marchi
2022-09-23 20:34         ` Fangrui Song
2022-09-24  5:43           ` Eli Zaretskii
2022-09-24  6:53 ` Enze Li [this message]
2022-09-24  7:13   ` Fangrui Song
2022-09-27 18:06     ` Tom Tromey
2022-09-27 18:08 ` Tom Tromey
2022-09-27 18:53   ` Fangrui Song
2022-09-29 11:43 ` Martin Liška
2022-09-29 20:17   ` Fangrui Song
2022-09-30  9:48     ` [PATCH][RFC] add --enable-zstd-compressed-debug-sections configure option Martin Liška
2022-09-30 11:25       ` Pedro Alves
2022-09-30 12:42         ` Martin Liška
2022-10-01  7:31           ` Fangrui Song
2022-10-03  7:49             ` Martin Liška
2022-10-03  7:50               ` [PATCH 1/2] refactor usage of compressed_debug_section_type Martin Liška
2022-10-11  7:14                 ` Martin Liška
2022-10-11 12:06                   ` Nick Clifton
2022-10-11 13:27                     ` Martin Liška
2022-10-03  7:50               ` [PATCH 2/2] add --enable-default-compressed-debug-sections-algorithm configure option Martin Liška
2022-10-11  7:14                 ` Martin Liška
2022-10-11 12:08                   ` Nick Clifton

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