[all-commits] [llvm/llvm-project] ff9ae3: [IRSymtab] Replace linear time lookup with DenseSe...

[Dhruv Chawla via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: ff9ae3f49d69c0c37e2fd009e7b7b239bfa5ece2
      https://github.com/llvm/llvm-project/commit/ff9ae3f49d69c0c37e2fd009e7b7b239bfa5ece2
  Author: Dhruv Chawla <dhruv263.dc at gmail.com>
  Date:   2023-09-15 (Fri, 15 Sep 2023)

  Changed paths:
    M llvm/lib/Object/IRSymtab.cpp

  Log Message:
  -----------
  [IRSymtab] Replace linear time lookup with DenseSet (#66376)

There is an inefficiency in the IRSymtab Builder where it does a lookup
of PreservedSymbols when calling addSymbol. This lookup is linear in
time, so it tends to be quite slow. Replacing it with DenseSet gives a
0.1% speedup:

https://llvm-compile-time-tracker.com/compare.php?from=02d27eac0f3f470a93635fc98ae990bf2a9809ed&to=62b09786fff4d53aa0c75b64aea48de241e4a856&stat=instructions:u

This change is quite similar to https://reviews.llvm.org/D157951.