[PATCH] D105410: [lld-macho] Parse relocations quickly by assuming sorted order

[Jez Ng via Phabricator via llvm-commits]

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clang and gcc both seem to emit relocations in reverse order of
address. That means we can match relocations to their containing
subsections in `O(relocs + subsections)` rather than the `O(relocs *
log(subsections))` that our previous binary search implementation
required.

I also removed the `is_sorted()` assert in ConcatOutputSection, since we
are now checking that property at parse time.

Numbers for linking chromium_framework on my 3.2 GHz 16-Core Intel Xeon W:

      N           Min           Max        Median           Avg        Stddev
  x  20          4.04          4.11         4.075        4.0775   0.018027756
  +  20          3.95          4.02          3.98         3.985   0.020900768
  Difference at 95.0% confidence
          -0.0925 +/- 0.0124919
          -2.26855% +/- 0.306361%
          (Student's t, pooled s = 0.0195172)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105410

Files:
  lld/MachO/ConcatOutputSection.cpp
  lld/MachO/InputFiles.cpp
  lld/test/MachO/invalid/unsorted-relocations.yaml

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