[libcxx-commits] [libcxx] [libc++] __key_equiv is sometimes 2x expensive (PR #175087)

[via libcxx-commits]

huixie90 wrote:

> _(existent)/0                                                   0.12         0.12         -0.01          -6.30%
> std::flat_map<string,_int>::count(key)_(existent)/1024                                              958.01       921.05        -36.96          -3.86%
> std::flat_map<string,_int>::count(key)_(existent)/32                                                662.44       621.16        -41.29          -6.23%
> std::flat_map<string,_int>::count(key)_(existent)/8192                                             1101.11      1098.67         -2.44          -0.22%
> std::flat_map<string,_int>::count(key)_(non-existent)

how can we explain the consistent speed up in the `count`, `lower_bound`, and `upper_bound` that don't seem to be impacted by the change?

https://github.com/llvm/llvm-project/pull/175087