binutils-gdb/config/zstd.m4
Fangrui Song 2cac01e3ff 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
...
```
2022-09-26 19:50:13 -07:00

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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([AC_ZSTD], [
AC_ARG_WITH(zstd,
[AS_HELP_STRING([--with-zstd], [support zstd compressed debug sections (default=auto)])],
[], [with_zstd=auto])
AS_IF([test "$with_zstd" != no],
[PKG_CHECK_MODULES(ZSTD, [libzstd], [
AC_DEFINE(HAVE_ZSTD, 1, [Define to 1 if zstd is enabled.])
], [
if test "$with_zstd" = yes; then
AC_MSG_ERROR([--with-zstd was given, but pkgconfig/libzstd.pc is not found])
fi
])
])
])