Copy in libbacktrace from gcc

This copies in libbacktrace from the gcc repository as it was in the
commit 62e420293a293608f383d9b9c7f2debd666e9fc9.  GDB is going to
start using this library soon.

A dependency between GDB and libbacktrace has already been added to
the top level Makefile, so, after this commit, when building GDB,
libbacktrace will be built first.  However, libbacktrace is not yet
linked into GDB, or used by GDB in any way.

It is possible to stop libbacktrace being built by configuring the
tree with --disable-libbacktrace.

This commit does NOT update src-release.sh, that will be done in the
next commit, this commit ONLY imports libbacktrace from gcc.  This
means that if you try to make a release of GDB from exactly this
commit then the release tar file will not include libbacktrace.
However, as libbacktrace is an optional dependency this is fine.

1 files changed, 581 insertions, 0 deletions

diff --git a/libbacktrace/configure.ac b/libbacktrace/configure.ac
new file mode 100644
index 0000000..43a33a6
--- /dev/null
+++ b/libbacktrace/configure.ac
@@ -0,0 +1,581 @@
+# configure.ac -- Backtrace configure script.
+# Copyright (C) 2012-2021 Free Software Foundation, Inc.
+
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+
+#     (1) Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+
+#     (2) Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in
+#     the documentation and/or other materials provided with the
+#     distribution.
+
+#     (3) The name of the author may not be used to
+#     endorse or promote products derived from this software without
+#     specific prior written permission.
+
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+# IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+AC_INIT(package-unused, version-unused,, libbacktrace)
+AC_CONFIG_SRCDIR(backtrace.h)
+AC_CONFIG_HEADER(config.h)
+
+if test -n "${with_target_subdir}"; then
+  AM_ENABLE_MULTILIB(, ..)
+fi
+
+AC_CANONICAL_SYSTEM
+target_alias=${target_alias-$host_alias}
+
+AC_USE_SYSTEM_EXTENSIONS
+
+libtool_VERSION=1:0:0
+AC_SUBST(libtool_VERSION)
+
+# 1.11.1: Require that version of automake.
+# foreign: Don't require README, INSTALL, NEWS, etc.
+# no-define: Don't define PACKAGE and VERSION.
+# no-dependencies: Don't generate automatic dependencies.
+#    (because it breaks when using bootstrap-lean, since some of the
+#    headers are gone at "make install" time).
+# -Wall: Issue all automake warnings.
+# -Wno-portability: Don't warn about constructs supported by GNU make.
+#    (because GCC requires GNU make anyhow).
+AM_INIT_AUTOMAKE([1.11.1 foreign no-dist no-define no-dependencies -Wall -Wno-portability])
+
+AM_MAINTAINER_MODE
+
+AC_ARG_WITH(target-subdir,
+[  --with-target-subdir=SUBDIR      Configuring in a subdirectory for target])
+
+# We must force CC to /not/ be precious variables; otherwise
+# the wrong, non-multilib-adjusted value will be used in multilibs.
+# As a side effect, we have to subst CFLAGS ourselves.
+m4_rename([_AC_ARG_VAR_PRECIOUS],[backtrace_PRECIOUS])
+m4_define([_AC_ARG_VAR_PRECIOUS],[])
+AC_PROG_CC
+m4_rename_force([backtrace_PRECIOUS],[_AC_ARG_VAR_PRECIOUS])
+
+AC_SUBST(CFLAGS)
+
+AC_PROG_RANLIB
+
+AC_PROG_AWK
+case "$AWK" in
+"") AC_MSG_ERROR([can't build without awk]) ;;
+esac
+
+AC_CHECK_PROG(DWZ, dwz, dwz)
+AM_CONDITIONAL(HAVE_DWZ, test "$DWZ" != "")
+
+LT_INIT
+AM_PROG_LIBTOOL
+
+AC_SYS_LARGEFILE
+
+backtrace_supported=yes
+
+if test -n "${with_target_subdir}"; then
+  # We are compiling a GCC library.  We can assume that the unwind
+  # library exists.
+  BACKTRACE_FILE="backtrace.lo simple.lo"
+else
+  AC_CHECK_HEADER([unwind.h],
+    [AC_CHECK_FUNC([_Unwind_Backtrace],
+	           [BACKTRACE_FILE="backtrace.lo simple.lo"],
+		   [BACKTRACE_FILE="nounwind.lo"
+                    backtrace_supported=no])],
+    [BACKTRACE_FILE="nounwind.lo"
+     backtrace_supported=no])
+fi
+AC_SUBST(BACKTRACE_FILE)
+
+EXTRA_FLAGS=
+if test -n "${with_target_subdir}"; then
+  EXTRA_FLAGS="-funwind-tables -frandom-seed=\$@"
+else
+  AC_CACHE_CHECK([for -funwind-tables option],
+    [libbacktrace_cv_c_unwind_tables],
+    [CFLAGS_hold="$CFLAGS"
+     CFLAGS="$CFLAGS -funwind-tables"
+     AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([static int f() { return 0; }], [return f();])],
+       [libbacktrace_cv_c_unwind_tables=yes],
+       [libbacktrace_cv_c_unwind_tables=no])
+     CFLAGS="$CFLAGS_hold"])
+  if test "$libbacktrace_cv_c_unwind_tables" = "yes"; then
+    EXTRA_FLAGS=-funwind-tables
+  fi
+  AC_CACHE_CHECK([for -frandom-seed=string option],
+    [libbacktrace_cv_c_random_seed_string],
+    [CFLAGS_hold="$CFLAGS"
+     CFLAGS="$CFLAGS -frandom-seed=conftest.lo"
+     AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([], [return 0;])],
+       [libbacktrace_cv_c_random_seed_string=yes],
+       [libbacktrace_cv_c_random_seed_string=no])
+     CFLAGS="$CFLAGS_hold"])
+  if test "$libbacktrace_cv_c_random_seed_string" = "yes"; then
+    EXTRA_FLAGS="$EXTRA_FLAGS -frandom-seed=\$@"
+  fi
+fi
+
+if test -n "${with_target_subdir}"; then
+  # Add CET specific flags is Intel CET is enabled.
+  GCC_CET_FLAGS(CET_FLAGS)
+  EXTRA_FLAGS="$EXTRA_FLAGS $CET_FLAGS"
+fi
+AC_SUBST(EXTRA_FLAGS)
+
+ACX_PROG_CC_WARNING_OPTS([-W -Wall -Wwrite-strings -Wstrict-prototypes \
+			  -Wmissing-prototypes -Wold-style-definition \
+			  -Wmissing-format-attribute -Wcast-qual],
+			  [WARN_FLAGS])
+
+if test -n "${with_target_subdir}"; then
+  WARN_FLAGS="$WARN_FLAGS -Werror"
+fi
+
+AC_SUBST(WARN_FLAGS)
+
+if test -n "${with_target_subdir}"; then
+  GCC_CHECK_UNWIND_GETIPINFO
+else
+  ac_save_CFFLAGS="$CFLAGS"
+  CFLAGS="$CFLAGS -Werror-implicit-function-declaration"
+  AC_MSG_CHECKING([for _Unwind_GetIPInfo])
+  AC_LINK_IFELSE(
+    [AC_LANG_PROGRAM(
+       [#include "unwind.h"
+	struct _Unwind_Context *context;
+	int ip_before_insn = 0;],
+	[return _Unwind_GetIPInfo (context, &ip_before_insn);])],
+	[have_unwind_getipinfo=yes], [have_unwind_getipinfo=no])
+  CFLAGS="$ac_save_CFLAGS"
+  AC_MSG_RESULT([$have_unwind_getipinfo])
+  if test "$have_unwind_getipinfo" = "yes"; then
+    AC_DEFINE(HAVE_GETIPINFO, 1, [Define if _Unwind_GetIPInfo is available.])
+  fi
+fi
+
+# Enable --enable-host-shared.
+AC_ARG_ENABLE(host-shared,
+[AS_HELP_STRING([--enable-host-shared],
+		[build host code as shared libraries])],
+[PIC_FLAG=-fPIC], [PIC_FLAG=])
+AC_SUBST(PIC_FLAG)
+
+# Enable Intel CET on Intel CET enabled host if jit is enabled.
+GCC_CET_HOST_FLAGS(CET_HOST_FLAGS)
+case x$enable_languages in
+*jit*)
+  ;;
+*)
+  CET_HOST_FLAGS=
+  ;;
+esac
+AC_SUBST(CET_HOST_FLAGS)
+
+# Test for __sync support.
+AC_CACHE_CHECK([__sync extensions],
+[libbacktrace_cv_sys_sync],
+[if test -n "${with_target_subdir}"; then
+   case "${host}" in
+   hppa*-*-hpux*) libbacktrace_cv_sys_sync=no ;;
+   *) libbacktrace_cv_sys_sync=yes ;;
+   esac
+ else
+   AC_LINK_IFELSE(
+     [AC_LANG_PROGRAM([int i;],
+                      [__sync_bool_compare_and_swap (&i, i, i);
+                       __sync_lock_test_and_set (&i, 1);
+                       __sync_lock_release (&i);])],
+     [libbacktrace_cv_sys_sync=yes],
+     [libbacktrace_cv_sys_sync=no])
+ fi])
+BACKTRACE_SUPPORTS_THREADS=0
+if test "$libbacktrace_cv_sys_sync" = "yes"; then
+  BACKTRACE_SUPPORTS_THREADS=1
+  AC_DEFINE([HAVE_SYNC_FUNCTIONS], 1,
+	    [Define to 1 if you have the __sync functions])
+fi
+AC_SUBST(BACKTRACE_SUPPORTS_THREADS)
+
+# Test for __atomic support.
+AC_CACHE_CHECK([__atomic extensions],
+[libbacktrace_cv_sys_atomic],
+[if test -n "${with_target_subdir}"; then
+   libbacktrace_cv_sys_atomic=yes
+ else
+   AC_LINK_IFELSE(
+     [AC_LANG_PROGRAM([int i;],
+     		      [__atomic_load_n (&i, __ATOMIC_ACQUIRE);
+		       __atomic_store_n (&i, 1, __ATOMIC_RELEASE);])],
+     [libbacktrace_cv_sys_atomic=yes],
+     [libbacktrace_cv_sys_atomic=no])
+ fi])
+if test "$libbacktrace_cv_sys_atomic" = "yes"; then
+  AC_DEFINE([HAVE_ATOMIC_FUNCTIONS], 1,
+	    [Define to 1 if you have the __atomic functions])
+fi
+
+# The library needs to be able to read the executable itself.  Compile
+# a file to determine the executable format.  The awk script
+# filetype.awk prints out the file type.
+AC_CACHE_CHECK([output filetype],
+[libbacktrace_cv_sys_filetype],
+[filetype=
+AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM([int i;], [int j;])],
+  [filetype=`${AWK} -f $srcdir/filetype.awk conftest.$ac_objext`],
+  [AC_MSG_FAILURE([compiler failed])])
+libbacktrace_cv_sys_filetype=$filetype])
+
+# Match the file type to decide what files to compile.
+FORMAT_FILE=
+backtrace_supports_data=yes
+case "$libbacktrace_cv_sys_filetype" in
+elf*) FORMAT_FILE="elf.lo" ;;
+macho) FORMAT_FILE="macho.lo" ;;
+pecoff) FORMAT_FILE="pecoff.lo"
+        backtrace_supports_data=no
+	;;
+xcoff*) FORMAT_FILE="xcoff.lo"
+        backtrace_supports_data=no
+        ;;
+*) AC_MSG_WARN([could not determine output file type])
+   FORMAT_FILE="unknown.lo"
+   backtrace_supported=no
+   ;;
+esac
+AC_SUBST(FORMAT_FILE)
+
+# ELF defines.
+elfsize=
+case "$libbacktrace_cv_sys_filetype" in
+elf32) elfsize=32 ;;
+elf64) elfsize=64 ;;
+*)     elfsize=unused
+esac
+AC_DEFINE_UNQUOTED([BACKTRACE_ELF_SIZE], [$elfsize], [ELF size: 32 or 64])
+AM_CONDITIONAL(HAVE_ELF, test "$FORMAT_FILE" = "elf.lo")
+
+# XCOFF defines.
+xcoffsize=
+case "$libbacktrace_cv_sys_filetype" in
+xcoff32) xcoffsize=32 ;;
+xcoff64) xcoffsize=64 ;;
+*)       xcoffsize=unused
+esac
+AC_DEFINE_UNQUOTED([BACKTRACE_XCOFF_SIZE], [$xcoffsize], [XCOFF size: 32 or 64])
+
+BACKTRACE_SUPPORTED=0
+if test "$backtrace_supported" = "yes"; then
+  BACKTRACE_SUPPORTED=1
+fi
+AC_SUBST(BACKTRACE_SUPPORTED)
+
+BACKTRACE_SUPPORTS_DATA=0
+if test "$backtrace_supports_data" = "yes"; then
+  BACKTRACE_SUPPORTS_DATA=1
+fi
+AC_SUBST(BACKTRACE_SUPPORTS_DATA)
+
+GCC_HEADER_STDINT(gstdint.h)
+
+AC_CHECK_HEADERS(sys/mman.h)
+if test "$ac_cv_header_sys_mman_h" = "no"; then
+  have_mmap=no
+else
+  if test -n "${with_target_subdir}"; then
+    # When built as a GCC target library, we can't do a link test.  We
+    # simply assume that if we have mman.h, we have mmap.
+    have_mmap=yes
+    case "${host}" in
+    *-*-msdosdjgpp)
+        # DJGPP has sys/man.h, but no mmap
+	have_mmap=no ;;
+    esac
+  else
+    AC_CHECK_FUNC(mmap, [have_mmap=yes], [have_mmap=no])
+  fi
+fi
+if test "$have_mmap" = "no"; then
+  VIEW_FILE=read.lo
+  ALLOC_FILE=alloc.lo
+else
+  VIEW_FILE=mmapio.lo
+  AC_PREPROC_IFELSE([AC_LANG_SOURCE([
+#include <sys/mman.h>
+#if !defined(MAP_ANONYMOUS) && !defined(MAP_ANON)
+  #error no MAP_ANONYMOUS
+#endif
+])], [ALLOC_FILE=mmap.lo], [ALLOC_FILE=alloc.lo])
+fi
+AC_SUBST(VIEW_FILE)
+AC_SUBST(ALLOC_FILE)
+
+BACKTRACE_USES_MALLOC=0
+if test "$ALLOC_FILE" = "alloc.lo"; then
+  BACKTRACE_USES_MALLOC=1
+fi
+AC_SUBST(BACKTRACE_USES_MALLOC)
+
+# Check for dl_iterate_phdr.
+AC_CHECK_HEADERS(link.h)
+if test "$ac_cv_header_link_h" = "no"; then
+  have_dl_iterate_phdr=no
+else
+  if test -n "${with_target_subdir}"; then
+    # When built as a GCC target library, we can't do a link test.
+    AC_EGREP_HEADER([dl_iterate_phdr], [link.h], [have_dl_iterate_phdr=yes],
+		    [have_dl_iterate_phdr=no])
+  else
+    AC_CHECK_FUNC([dl_iterate_phdr], [have_dl_iterate_phdr=yes],
+		  [have_dl_iterate_phdr=no])
+  fi
+fi
+if test "$have_dl_iterate_phdr" = "yes"; then
+  AC_DEFINE(HAVE_DL_ITERATE_PHDR, 1, [Define if dl_iterate_phdr is available.])
+fi
+
+# Check for header file for Mach-O image functions.
+AC_CHECK_HEADERS(mach-o/dyld.h)
+
+# Check for loadquery.
+AC_CHECK_HEADERS(sys/ldr.h)
+if test "$ac_cv_header_sys_ldr_h" = "no"; then
+  have_loadquery=no
+else
+  if test -n "${with_target_subdir}"; then
+    # When built as a GCC target library, we can't do a link test.
+    AC_EGREP_HEADER([loadquery], [sys/ldr.h], [have_loadquery=yes],
+		    [have_loadquery=no])
+  else
+    AC_CHECK_FUNC([loadquery], [have_loadquery=yes],
+		  [have_loadquery=no])
+  fi
+fi
+if test "$have_loadquery" = "yes"; then
+  AC_DEFINE(HAVE_LOADQUERY, 1, [Define if AIX loadquery is available.])
+fi
+
+# Check for the fcntl function.
+if test -n "${with_target_subdir}"; then
+   case "${host}" in
+   *-*-mingw*) have_fcntl=no ;;
+   *) have_fcntl=yes ;;
+   esac
+else
+  AC_CHECK_FUNC(fcntl, [have_fcntl=yes], [have_fcntl=no])
+fi
+if test "$have_fcntl" = "yes"; then
+  AC_DEFINE([HAVE_FCNTL], 1,
+	    [Define to 1 if you have the fcntl function])
+fi
+
+AC_CHECK_DECLS([strnlen, getpagesize])
+AC_CHECK_FUNCS(lstat readlink)
+
+# Check for getexecname function.
+if test -n "${with_target_subdir}"; then
+   case "${host}" in
+   *-*-solaris2*) have_getexecname=yes ;;
+   *) have_getexecname=no ;;
+   esac
+else
+  AC_CHECK_FUNC(getexecname, [have_getexecname=yes], [have_getexecname=no])
+fi
+if test "$have_getexecname" = "yes"; then
+  AC_DEFINE(HAVE_GETEXECNAME, 1, [Define if getexecname is available.])
+fi
+
+# Check for sysctl definitions.
+
+AC_CACHE_CHECK([for KERN_PROC],
+[libbacktrace_cv_proc],
+[AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM([
+#include <sys/types.h>
+#include <sys/sysctl.h>
+], [int mib0 = CTL_KERN; int mib1 = KERN_PROC; int mib2 = KERN_PROC_PATHNAME;])],
+  [libbacktrace_cv_proc=yes],
+  [libbacktrace_cv_proc=no])])
+if test "$libbacktrace_cv_proc" = "yes"; then
+  AC_DEFINE([HAVE_KERN_PROC], 1,
+            [Define to 1 if you have KERN_PROC and KERN_PROC_PATHNAME in <sys/sysctl.h>.])
+fi
+
+AC_CACHE_CHECK([for KERN_PROG_ARGS],
+[libbacktrace_cv_procargs],
+[AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM([
+#include <sys/types.h>
+#include <sys/sysctl.h>
+], [int mib0 = CTL_KERN; int mib1 = KERN_PROC_ARGS; int mib2 = KERN_PROC_PATHNAME;])],
+  [libbacktrace_cv_procargs=yes],
+  [libbacktrace_cv_procargs=no])])
+if test "$libbacktrace_cv_procargs" = "yes"; then
+  AC_DEFINE([HAVE_KERN_PROC_ARGS], 1,
+            [Define to 1 if you have KERN_PROCARGS and KERN_PROC_PATHNAME in <sys/sysctl.h>.])
+fi
+
+# Check for the clock_gettime function.
+AC_CHECK_FUNCS(clock_gettime)
+clock_gettime_link=
+# At least for glibc, clock_gettime is in librt.  But don't
+# pull that in if it still doesn't give us the function we want.  This
+# test is copied from libgomp, and modified to not link in -lrt as
+# we're using this for test timing only.
+if test "$ac_cv_func_clock_gettime" = no; then
+  AC_CHECK_LIB(rt, clock_gettime,
+    [CLOCK_GETTIME_LINK=-lrt
+     AC_DEFINE(HAVE_CLOCK_GETTIME, 1,
+	       [Define to 1 if you have the `clock_gettime' function.])])
+fi
+AC_SUBST(CLOCK_GETTIME_LINK)
+
+dnl Test whether the compiler supports the -pthread option.
+AC_CACHE_CHECK([whether -pthread is supported],
+[libgo_cv_lib_pthread],
+[CFLAGS_hold=$CFLAGS
+CFLAGS="$CFLAGS -pthread"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([int i;])],
+[libgo_cv_lib_pthread=yes],
+[libgo_cv_lib_pthread=no])
+CFLAGS=$CFLAGS_hold])
+PTHREAD_CFLAGS=
+if test "$libgo_cv_lib_pthread" = yes; then
+  PTHREAD_CFLAGS=-pthread
+fi
+AC_SUBST(PTHREAD_CFLAGS)
+
+AM_CONDITIONAL(HAVE_PTHREAD, test "$libgo_cv_lib_pthread" = yes)
+
+dnl Test whether the compiler and the linker support the -gdwarf-5 option.
+AC_CACHE_CHECK([whether -gdwarf-5 is supported],
+[libbacktrace_cv_lib_dwarf5],
+[CFLAGS_hold=$CFLAGS
+CFLAGS="$CFLAGS -gdwarf-5"
+AC_LINK_IFELSE([AC_LANG_PROGRAM([int i;], [return 0;])],
+[libbacktrace_cv_lib_dwarf5=yes],
+[libbacktrace_cv_lib_dwarf5=no])
+CFLAGS=$CFLAGS_hold])
+AM_CONDITIONAL(HAVE_DWARF5, test "$libbacktrace_cv_lib_dwarf5" = yes)
+
+AC_CHECK_LIB([z], [compress],
+    [AC_DEFINE(HAVE_ZLIB, 1, [Define if -lz is available.])])
+AM_CONDITIONAL(HAVE_ZLIB, test "$ac_cv_lib_z_compress" = yes)
+
+dnl Test whether the linker supports the --compress_debug_sections option.
+AC_CACHE_CHECK([whether --compress-debug-sections is supported],
+[libgo_cv_ld_compress],
+[LDFLAGS_hold=$LDFLAGS
+LDFLAGS="$LDFLAGS -Wl,--compress-debug-sections=zlib-gnu"
+AC_LINK_IFELSE([AC_LANG_PROGRAM(,)],
+[libgo_cv_ld_compress=yes],
+[libgo_cv_ld_compress=no])
+LDFLAGS=$LDFLAGS_hold])
+AM_CONDITIONAL(HAVE_COMPRESSED_DEBUG, test "$libgo_cv_ld_compress" = yes)
+
+AC_ARG_VAR(OBJCOPY, [location of objcopy])
+AC_CHECK_PROG(OBJCOPY, objcopy, objcopy,)
+AC_CHECK_PROG(READELF, readelf, readelf)
+AC_CACHE_CHECK([whether objcopy supports debuglink],
+[libbacktrace_cv_objcopy_debuglink],
+[if test -n "${with_target_subdir}"; then
+  libbacktrace_cv_objcopy_debuglink=no
+elif ! test -n "${OBJCOPY}"; then
+  libbacktrace_cv_objcopy_debuglink=no
+elif ${OBJCOPY} --help | fgrep add-gnu-debuglink >/dev/null 2>&1; then
+  libbacktrace_cv_objcopy_debuglink=yes
+else
+  libbacktrace_cv_objcopy_debuglink=no
+fi])
+AM_CONDITIONAL(HAVE_OBJCOPY_DEBUGLINK, test "$libbacktrace_cv_objcopy_debuglink" = yes)
+
+AC_ARG_VAR(DSYMUTIL, [location of dsymutil])
+AC_CHECK_PROG(DSYMUTIL, dsymutil, dsymutil)
+AM_CONDITIONAL(USE_DSYMUTIL, test -n "${DSYMUTIL}" -a "$FORMAT_FILE" = "macho.lo")
+
+AC_ARG_VAR(NM, [location of nm])
+AC_CHECK_PROG(NM, nm, nm)
+
+AC_CHECK_PROG(XZ, xz, xz)
+AM_CONDITIONAL(HAVE_XZ, test "$XZ" != "")
+AC_CHECK_PROG(COMM, comm, comm)
+AM_CONDITIONAL(HAVE_COMM, test "$COMM" != "")
+
+AM_CONDITIONAL(HAVE_MINIDEBUG,
+  test "${with_target_subdir}" = "" -a "$FORMAT_FILE" = "elf.lo" -a "${OBJCOPY}" != "" -a "${NM}" != "" -a "${XZ}" != "" -a "${COMM}" != "")
+
+AC_CHECK_LIB([lzma], [lzma_auto_decoder],
+    [AC_DEFINE(HAVE_LIBLZMA, 1, [Define if -llzma is available.])])
+AM_CONDITIONAL(HAVE_LIBLZMA, test "$ac_cv_lib_lzma_lzma_auto_decoder" = yes)
+
+AC_CACHE_CHECK([whether tests can run],
+  [libbacktrace_cv_sys_native],
+  [AC_RUN_IFELSE([AC_LANG_PROGRAM([], [return 0;])],
+     [libbacktrace_cv_sys_native=yes],
+     [libbacktrace_cv_sys_native=no],
+     [libbacktrace_cv_sys_native=no])])
+AM_CONDITIONAL(NATIVE, test "$libbacktrace_cv_sys_native" = "yes")
+
+if test "${multilib}" = "yes"; then
+  multilib_arg="--enable-multilib"
+else
+  multilib_arg=
+fi
+
+AC_CONFIG_FILES(Makefile backtrace-supported.h)
+AC_CONFIG_FILES(install-debuginfo-for-buildid.sh, chmod +x install-debuginfo-for-buildid.sh)
+
+# We need multilib support, but only if configuring for the target.
+AC_CONFIG_COMMANDS([default],
+[if test -n "$CONFIG_FILES"; then
+   if test -n "${with_target_subdir}"; then
+     # Multilibs need MULTISUBDIR defined correctly in certain makefiles so
+     # that multilib installs will end up installed in the correct place.
+     # The testsuite needs it for multilib-aware ABI baseline files.
+     # To work around this not being passed down from config-ml.in ->
+     # srcdir/Makefile.am -> srcdir/{src,libsupc++,...}/Makefile.am, manually
+     # append it here.  Only modify Makefiles that have just been created.
+     #
+     # Also, get rid of this simulated-VPATH thing that automake does.
+     cat > vpsed << \_EOF
+  s!`test -f '$<' || echo '$(srcdir)/'`!!
+_EOF
+     for i in $SUBDIRS; do
+      case $CONFIG_FILES in
+       *${i}/Makefile*)
+	 #echo "Adding MULTISUBDIR to $i/Makefile"
+	 sed -f vpsed $i/Makefile > tmp
+	 grep '^MULTISUBDIR =' Makefile >> tmp
+	 mv tmp $i/Makefile
+	 ;;
+      esac
+     done
+     rm vpsed
+   fi
+ fi
+],
+[
+# Variables needed in config.status (file generation) which aren't already
+# passed by autoconf.
+SUBDIRS="$SUBDIRS"
+])
+
+AC_OUTPUT