Hi @MessyHack!

Thank you for your pull request and welcome to our community.

Action Required

In order to merge any pull request (code, docs, etc.), we require contributors to sign our Contributor License Agreement, and we don't seem to have one on file for you.

Process

In order for us to review and merge your suggested changes, please sign at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need to sign the corporate CLA.

Once the CLA is signed, our tooling will perform checks and validations. Afterwards, the pull request will be tagged with CLA signed. The tagging process may take up to 1 hour after signing. Please give it that time before contacting us about it.

If you have received this in error or have any questions, please contact us at [email protected]. Thanks!

signed CLA

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Meta Open Source project. Thanks!

Reasoning looks good,

I'm curious if it impacts performance in any way on Visual x64.

There's a slight perf gain when building with MSVC and targeting AVX2. (Using current VS 2022 preview)
I should double check the SSE behavior

When targeting AVX2, MSVC will use bzhi (bmi2 instruction). This only happens when targeting AVX2.

Reasoning looks good,
I'm curious if it impacts performance in any way on Visual x64.

There's a slight perf gain when building with MSVC and targeting AVX2. (Using current VS 2022 preview) I should double check the SSE behavior

When targeting AVX2, MSVC will use bzhi (bmi2 instruction). This only happens when targeting AVX2.

SSE seems ok; but not really that different.

(before change; SSE)
3#Lorem ipsum : 10000000 -> 2983345 (x3.352), 337.1 MB/s 1181.9 MB/s
vs
(after change; SSE
3#Lorem ipsum : 10000000 -> 2983345 (x3.352), 339.4 MB/s 1192.0 MB/s

When targeting AVX2, MSVC will use bzhi (bmi2 instruction). This only happens when targeting AVX2.

I thinks that's the main goal.
We observed that bmi2 gives a small but solid performance gain.
Enabling that should be beneficial.