[PATCH] D52083: [clangd] Store OR iterator children in heap

[Kirill Bobyrev via Phabricator via cfe-commits]

kbobyrev created this revision.
kbobyrev added reviewers: ioeric, sammccall, ilya-biryukov.
kbobyrev added a project: clang-tools-extra.
Herald added subscribers: kadircet, arphaman, jkorous, MaskRay.

Use min-heap invariant for OR iterator's children. This helps to avoid iterating through all children in `reachedEnd()`, `peek()` and allows early-stopping in `consume()` and `advance()`.

This optimization results in ~8-9% of performance boost on benchmark with ~4300 real queries to LLVM static index.

benchmark's `compare.py` output:

  benchmark                    Time             CPU      Time Old      Time New       CPU Old       CPU New
  ---------------------------------------------------------------------------------------------------------
  DexQueries                -0.0706         -0.0706    4719149241    4385985920    4719100956    4385946455


https://reviews.llvm.org/D52083

Files:
  clang-tools-extra/clangd/index/dex/Iterator.cpp
  clang-tools-extra/unittests/clangd/DexTests.cpp

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