[PATCH] D142862: [Support] change StringMap hash function from djbHash to xxHash

Wed Feb 1 21:06:35 PST 2023

erikdesjardins added a comment.

In D142862#4089860 <https://reviews.llvm.org/D142862#4089860>, @serge-sans-paille wrote:

> Can  you take a shot against https://llvm-compile-time-tracker.com/ so that we get an hint of the practical speedup?

I ran rustc perf tests using a patched LLVM in https://github.com/rust-lang/rust/pull/107552#issuecomment-1411927687,
you can see the results here: https://perf.rust-lang.org/compare.html?start=ad8e1dc2863f63c35ef3ceef3064d0851a1d2582&end=8aaf54b663467dc48ff24d764aa9f73c61db2733&stat=instructions:u
Improvements from 0.2%-2% on various benchmarks, no regressions.

@serge-sans-paille it looks like you have access to llvm-compile-time-tracker, can you push this patch up so we can see those perf tests too?
Probable oneliner: `git remote add erikdesjardins https://github.com/erikdesjardins/llvm-project.git && git fetch erikdesjardins && git push origin erikdesjardins/xxhash-perf:refs/heads/perf/xxhash`

> Do you intend to (optionnaly) provide XXH3 as described in https://github.com/Cyan4973/xxHash ?

The current version of xxhash in tree is stripped down to just xxhash64. I don't intend to change that as part of this patch.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142862/new/

https://reviews.llvm.org/D142862