tree 58fdf856bab2e4db919b687fdb5513031460a96f
parent da0e851c7542036c2c6e71b28c51abf97e927f4c
author Ilya Biryukov <ibiryukov@google.com> 1566291270 +0000
committer Ilya Biryukov <ibiryukov@google.com> 1566291270 +0000

[clangd] Skip function bodies inside processed files while indexing

Summary:
This significantly improves performance of background indexing.

We do not collect references and declarations inside the processed
files, so this does not affect the final indexing results.

The idea is borrowed from libclang, which has a similar optimization in
its indexing functionality.

Measurements show a nice decrease in indexing time, up to ~40% for
building the whole index. These are not proper benchmarks, so one should
not rely on these results too much.

1. Rebuilding the whole index for LLVM:
  - Before. Total time: 14m58s.
    ./bin/clangd -pch-storage=memory < ./clangd.input  23917.67s user 515.86s system 2718% cpu 14:58.68 total
  - After. Total time: 8m41s.
    ./bin/clangd -pch-storage=memory < ./clangd.input  13627.29s user 288.10s system 2672% cpu 8:40.67 total

2. Rebuilding index after removing shards matching '*clangd*' (case-insensitively):
  - Before. Total time: 30s.
    ./bin/clangd -pch-storage=memory < ./clangd.input  130.94s user 6.82s system 452% cpu 30.423 total
  - After. Total time: 26s.
    ./bin/clangd -pch-storage=memory < ./clangd.input  80.51s user 5.40s system 333% cpu 25.777 total

Reviewers: kadircet, sammccall

Reviewed By: kadircet

Subscribers: MaskRay, jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66226

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@369349 91177308-0d34-0410-b5e6-96231b3b80d8