[PATCH] D80859: [lld-macho] Ensure __bss sections we output have file offset of zero

[Jez Ng via Phabricator via llvm-commits]

int3 created this revision.
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I'm not sure it's strictly necessary, but it's what ld64 does. Moreover, the
previous implementation was buggy: llvm-mc emits `__bss` sections with an offset
of zero, but we weren't expecting that in our input, so we were copying non-zero
data from the start of the file and putting it in `__bss`, with obviously
undesirable runtime results.

I debated on whether to make a special ZeroFillSection -- separate from a
regular InputSection -- but it seemed like too much work for now. But I'm happy
to refactor if anyone feels strongly about having it as a separate class.

Depends on D80857 <https://reviews.llvm.org/D80857>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D80859

Files:
  lld/MachO/InputFiles.cpp
  lld/MachO/InputSection.cpp
  lld/MachO/InputSection.h
  lld/MachO/Writer.cpp
  lld/test/MachO/bss.s

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