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
...
```
This commit is contained in:
Fangrui Song
2022-09-26 19:50:13 -07:00
committed by Fangrui Song
parent e122316b7c
commit 2cac01e3ff
56 changed files with 1490 additions and 254 deletions

View File

@@ -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