[PATCH] D122974: prevent ConstString from calling djbHash() more than once

Fri Apr 29 08:41:38 PDT 2022

llunak added a comment.

In D122974#3482556 <https://reviews.llvm.org/D122974#3482556>, @labath wrote:

> Interesting. I don't know if I missed this somewhere, but could explain what kind of a map operation can lldb perform without computing the hash at least once?

All of them :). Computing is not the only way of obtaining the hash of a string. LLDB index cache (settings set symbols.enable-lldb-index-cache true) stores a big bunch of strings and when loading them back into ConstString the next time djbHash() is ~15% of total CPU LLDB startup time. That could be saved if the cache cached the hash values too.

Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D122974