[PATCH] D118797: [lld-macho][nfc] Eliminate InputSection::Shared

[Jez Ng via Phabricator via llvm-commits]

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Earlier in LLD's evolution, I tried to create the illusion that
subsections were indistinguishable from "top-level" sections. Thus, even
though the subsections shared many common field values, I hid those
common values away in a private Shared struct (see D105305 <https://reviews.llvm.org/D105305>). More
recently, however, @gkm added a public `Section` struct in D113241 <https://reviews.llvm.org/D113241> that
served as an explicit way to store values that are common to an entire
set of subsections (aka InputSections). Now that we have another "common
value" struct, `Shared` has been rendered redundant. All its fields can
be moved into `Section` instead.

P.S. I do think that having both `Section` and `InputSection` makes for
a slightly confusing naming scheme. I considered renaming `InputSection`
to `Subsection`, but that would break the symmetry with `OutputSection`.
It would also make us deviate from LLD-ELF's naming scheme.

This change is perf-neutral on my 3.2 GHz 16-Core Intel Xeon W machine:

             base           diff           difference (95% CI)
  sys_time   1.258 ± 0.031  1.248 ± 0.023  [  -1.6% ..   +0.1%]
  user_time  3.659 ± 0.047  3.658 ± 0.041  [  -0.5% ..   +0.4%]
  wall_time  4.640 ± 0.085  4.625 ± 0.063  [  -1.0% ..   +0.3%]
  samples    49             61


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118797

Files:
  lld/MachO/ConcatOutputSection.cpp
  lld/MachO/Driver.cpp
  lld/MachO/InputFiles.cpp
  lld/MachO/InputFiles.h
  lld/MachO/InputSection.cpp
  lld/MachO/InputSection.h
  lld/MachO/SymbolTable.cpp
  lld/MachO/SyntheticSections.cpp
  lld/MachO/Writer.cpp

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