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| author | Sam McCall <sam.mccall@gmail.com> | 2022-10-05 02:22:38 +0200 |
|---|---|---|
| committer | Sam McCall <sam.mccall@gmail.com> | 2022-10-05 20:55:53 +0200 |
| commit | 6ea83fc98fd120066c3c42d88c5517ab811152bc (patch) | |
| tree | 165403ebfad2780bc3ad6277a5247dda5ab00cc4 /clang/lib/Basic/SourceManager.cpp | |
| parent | 34004d2d03a9a4908254ebbe5e60b6c99c9425d8 (diff) | |
| download | llvm-6ea83fc98fd120066c3c42d88c5517ab811152bc.zip llvm-6ea83fc98fd120066c3c42d88c5517ab811152bc.tar.gz llvm-6ea83fc98fd120066c3c42d88c5517ab811152bc.tar.bz2 | |
[clangd] Don't clone SymbolSlab::Builder arenas when finalizing.
SymbolSlab::Builder has an arena to store strings of owned symbols, and
deduplicates them. build() copies all the strings and deduplicates them again!
This is potentially useful: we may have overwritten a symbol and
rendered some strings unreachable.
However in practice this is not the case. When testing on a variety of
files in LLVM (e.g. SemaExpr.cpp), the strings for the full preamble
index are 3MB and shrink by 0.4% (12KB). For comparison the serializde
preamble is >50MB.
There are also hundreds of smaller slabs (file sharding) that do not shrink at
all.
CPU time spent on this is significant (something like 3-5% of buildPreamble).
We're better off not bothering.
Differential Revision: https://reviews.llvm.org/D135231
Diffstat (limited to 'clang/lib/Basic/SourceManager.cpp')
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