binutils, gdb: support zstd compressed debug sections

PR29397 PR29563: Add new configure option --with-zstd which 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
...
```

9 files changed, 217 insertions, 16 deletions

diff --git a/binutils/Makefile.in b/binutils/Makefile.in
index 78d32b3..6de4e23 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/NEWS b/binutils/NEWS
index 8c2c416..83c73d0 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -1,5 +1,11 @@
 -*- text -*-
 
+* objcopy --decompress-debug-sections now supports zstd compressed debug
+  sections.  The new option --compress-debug-sections=zstd compresses debug
+  sections with zstd.
+
+* addr2line and objdump --dwarf now support zstd compressed debug sections.
+
 * The dlltool program now accepts --deterministic-libraries and
   --non-deterministic-libraries as command line options to control whether or
   not it generates deterministic output libraries.  If neither of these options
diff --git a/binutils/aclocal.m4 b/binutils/aclocal.m4
index a877fa7..28271f5 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 c5fb919..bee8c07 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 4c0c391..0d6bde7 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 +13499,127 @@ 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 0798d84..9b75396 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
+AC_ZSTD
 
 BFD_BINARY_FOPEN
 
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 1499db5..34a4164 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 4326175..fc668f0 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 c88da74..4e74c82 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