[PATCH] D79918: [clangd] Don't create as much garbage while building Dex index.

[Sam McCall via Phabricator via cfe-commits]

sammccall created this revision.
sammccall added a reviewer: kbobyrev.
Herald added subscribers: cfe-commits, usaxena95, kadircet, arphaman, mgrang, jkorous, MaskRay, ilya-biryukov.
Herald added a project: clang.

The Token objects are relatively expensive and we were spending a lot of
CPU creating them for each trigram emitted. Instead, use a tiny trigram
structure until we're ready to finalize the index.

This improves the new BuildDex benchmark by 20%. This code is hot and on
the critical path in clangd: it runs after a new preamble is built.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D79918

Files:
  clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp
  clang-tools-extra/clangd/index/dex/Dex.cpp
  clang-tools-extra/clangd/index/dex/Trigram.cpp
  clang-tools-extra/clangd/index/dex/Trigram.h
  clang-tools-extra/clangd/test/Inputs/requests.json
  clang-tools-extra/clangd/unittests/DexTests.cpp

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