[PATCH] D51287: [clangd] Use TRUE iterator instead of complete posting list

[Kirill Bobyrev via Phabricator via cfe-commits]

kbobyrev created this revision.
kbobyrev added a reviewer: ilya-biryukov.
kbobyrev added a project: clang-tools-extra.
Herald added subscribers: kadircet, arphaman, jkorous, MaskRay.
kbobyrev edited the summary of this revision.

Stop using `$$$` (empty) trigram and generating a posting list with all items. Since TRUE iterator is already implemented and correctly inserted when there are no real trigram posting lists, this is a valid transformation.

Benchmarks show that this simple change allows ~30% speedup on dataset of real completion queries.

Before

  -------------------------------------------------------
  Benchmark                Time           CPU Iterations
  -------------------------------------------------------
  DexAdHocQueries    5640321 ns    5640265 ns        120
  DexRealQ         939835603 ns  939830296 ns          1

After

  -------------------------------------------------------
  Benchmark                Time           CPU Iterations
  -------------------------------------------------------
  DexAdHocQueries    3452014 ns    3451987 ns        203
  DexRealQ         667455912 ns  667455750 ns          1


https://reviews.llvm.org/D51287

Files:
  clang-tools-extra/clangd/index/dex/Trigram.cpp


Index: clang-tools-extra/clangd/index/dex/Trigram.cpp
===================================================================
--- clang-tools-extra/clangd/index/dex/Trigram.cpp
+++ clang-tools-extra/clangd/index/dex/Trigram.cpp
@@ -67,10 +67,6 @@
     UniqueTrigrams.insert(Token(Token::Kind::Trigram, Chars));
   };
 
-  // FIXME(kbobyrev): Instead of producing empty trigram for each identifier,
-  // just use True Iterator on the query side when the query string is empty.
-  add({{END_MARKER, END_MARKER, END_MARKER}});
-
   if (TwoHeads.size() == 2)
     add({{TwoHeads.front(), TwoHeads.back(), END_MARKER}});
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D51287.162633.patch
Type: text/x-patch
Size: 615 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20180827/de3ac096/attachment-0001.bin>