[libcxx-commits] [PATCH] D118029: Introduce branchless sorting functions for sort3, sort4 and sort5.

[Marco Gelmi via Phabricator via libcxx-commits]

marcogelmi added a comment.

> I'm guessing all the ternaries are making the compiler generate `cmov`s?

yes that's correct

> I noticed that the benchmarks for size 4 are generally pretty bad. Do you know if anything can be done there?

Random 4 is actually very good. It's bad for deterministic orderings because the benchmark just keeps on calling sort4 with the same ordering over and over again, so the branch predictor has a very easy job. I suspect this type of data pattern is not very realistic.

> I haven't yet looked at the logic itself very closely.




Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D118029/new/

https://reviews.llvm.org/D118029