[PATCH] D136000: [lld-macho] Don't fold subsections with symbols at nonzero offsets

[Jez Ng via Phabricator via llvm-commits]

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Symbols occur at non-zero offsets in a subsection if they are
`.alt_entry` symbols, or if `.subsections_via_symbols` is omitted.

It doesn't seem like ld64 supports folding those subsections either.
Moreover, supporting this it makes `foldIdentical` a lot more
complicated to implement. The existing implementation has some
questionable behavior around STABS omission -- if a section with an
non-zero offset symbol was folded into one without, we would omit the
STABS entry for the non-zero offset symbol.

I will be following up with a diff that makes `foldIdentical` zero out
the symbol sizes for folded symbols. Again, this is much easier to
implement if we don't have to worry about non-zero offsets.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D136000

Files:
  lld/MachO/ICF.cpp
  lld/MachO/InputFiles.cpp
  lld/MachO/InputSection.cpp
  lld/MachO/InputSection.h
  lld/test/MachO/icf.s

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