llvm-objcopy's --compress-debug-sections doesn't work

[hukeyue]

Passed with option --compress-debug-sections

➜  build-mingw-x86_64 git:(develop) ✗ /Users/keeyou/yass-develop/third_party/llvm-build/Release+Asserts/bin/llvm-objcopy --only-keep-debug --compress-debug-sections yass.exe yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ ls -alh yass.exe*
-rwxr-xr-x  1 keeyue  staff    45M Apr  6 09:05 yass.exe
-rwxr-xr-x  1 keeyue  staff    44M Apr  6 09:15 yass.exe.dbg

Passed without option --compress-debug-sections

➜  build-mingw-x86_64 git:(develop) ✗ rm yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ /Users/keeyou/yass-develop/third_party/llvm-build/Release+Asserts/bin/llvm-objcopy --only-keep-debug yass.exe yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ ls -alh yass.exe*
-rwxr-xr-x  1 keeyue  staff    45M Apr  6 09:05 yass.exe
-rwxr-xr-x  1 keeyue  staff    44M Apr  6 09:15 yass.exe.dbg

➜  build-mingw-x86_64 git:(develop) ✗ ~/clang+llvm-22.1.2-arm64-apple-darwin20.1.0/bin/llvm-objdump --all-headers yass.exe.dbg > yass.exe.dbg.headers.txt
➜  build-mingw-x86_64 git:(develop) ✗ /Users/keeyou/yass-develop/third_party/llvm-build/Release+Asserts/bin/llvm-objcopy --only-keep-debug --compress-debug-sections yass.exe yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ ~/clang+llvm-22.1.2-arm64-apple-darwin20.1.0/bin/llvm-objdump --all-headers yass.exe.dbg > yass.exe.dbg.headers.with-compress.txt
➜  build-mingw-x86_64 git:(develop) ✗ diff yass.exe.dbg.headers.with-compress.txt yass.exe.dbg.headers.txt
➜  build-mingw-x86_64 git:(develop) ✗ echo $?
0

yass.exe.dbg.headers.txt
yass.exe.dbg.headers.with-compress.txt

BTW option --extract-dwo doesn't work as well:

➜  build-mingw-x86_64 git:(develop) ✗ /Users/keeyou/yass-develop/third_party/llvm-build/Release+Asserts/bin/llvm-objcopy --extract-dwo yass.exe yass.dwo
/Users/keeyou/yass-develop/third_party/llvm-build/Release+Asserts/bin/llvm-objcopy: error: option is not supported for COFF

[hukeyue]

To be more correct, the output file is identical whether it is passed with --compress-debug-sections

➜  build-mingw-x86_64 git:(develop) ✗ ../third_party/llvm-mingw-20250709-ucrt-macos-universal/bin/llvm-objcopy --only-keep-debug --compress-debug-sections yass.exe yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ sha1sum yass.exe.dbg
5eed3dc46b71d44e5b17315bd75136b430c01720  yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ rm yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ ../third_party/llvm-mingw-20250709-ucrt-macos-universal/bin/llvm-objcopy --only-keep-debug yass.exe yass.exe.dbg
➜  build-mingw-x86_64 git:(develop) ✗ sha1sum yass.exe.dbg
5eed3dc46b71d44e5b17315bd75136b430c01720  yass.exe.dbg

➜  build-mingw-x86_64 git:(develop) ✗ ../third_party/llvm-mingw-20250709-ucrt-macos-universal/bin/llvm-objcopy --version
llvm-objcopy, compatible with GNU objcopy
LLVM (http://llvm.org/):
  LLVM version 20.1.8
  Optimized build.
➜  build-mingw-x86_64 git:(develop) ✗ /Users/keeyou/yass-develop/third_party/llvm-build/Release+Asserts/bin/llvm-objcopy --version
llvm-objcopy, compatible with GNU objcopy
LLVM (http://llvm.org/):
  LLVM version 23.0.0git
  Optimized build.

[hukeyue]

For comparison, binutils's objcopy works as expected:

You can checked it with .zdebug sections
yass.exe.dbg.headers.with-binutils.txt

BTW I obtained the copy the mingw binaries from winlibs.com aka this url

[hukeyue]

I created an issue at llvm-project aka llvm/llvm-project#190574. Hope someone notices it.