tree 0d143dcd636ef32e9e1f74bd92d9a375da0fbca6
parent 027a38a0d8f5a1c73b032a38ed4f2b147fdaec42
author Fangrui Song <i@maskray.me> 1710266174 -0700
committer Copybara-Service <copybara-worker@google.com> 1710266237 -0700

[ELF] Add --compress-section to compress matched non-SHF_ALLOC sections

--compress-sections <section-glib>=[none|zlib|zstd] is similar to
--compress-debug-sections but applies to broader sections without the
SHF_ALLOC flag. lld will report an error if a SHF_ALLOC section is
matched. An interesting use case is to compress `.strtab`/`.symtab`,
which consume a significant portion of the file size (15.1% for a
release build of Clang).

An older revision is available at https://reviews.llvm.org/D154641 .
This patch focuses on non-allocated sections for safety. Moving
`maybeCompress` as D154641 does not handle STT_SECTION symbols for
`-r --compress-debug-sections=zlib` (see `relocatable-section-symbol.s`
from #66804).

Since different output sections may use different compression
algorithms, we need CompressedData::type to generalize
config->compressDebugSections.

GNU ld feature request: https://sourceware.org/bugzilla/show_bug.cgi?id=27452

Link: https://discourse.llvm.org/t/rfc-compress-arbitrary-sections-with-ld-lld-compress-sections/71674

Pull Request: https://github.com/llvm/llvm-project/pull/84855

GitOrigin-RevId: f1ca2a09671e4d4acc2bea362b39268ed7883b6d