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cpufeatures: `cfg_select!`-like macro

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#1,529 4 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
45/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Active
Tech stack
rust
Domain
performance

Research direction

Start at the cpufeatures::new! entry point and compare the requested behavior with Rust's cfg_select! macro semantics. Trace how generated feature checks are read, then define and test an ordered selection interface that avoids repeated atomic reads and preserves the fallback; done when the requested feature combinations select the correct branch.

Written by the indexing model from the issue text.

Description

More than once I wrote a piece of code that has the following shape:

cpufeatures::new!(has_avx512f_vaes, "avx512f", "vaes");
if has_avx512f_vaes::get() {
    return /* .. */;
}

cpufeatures::new!(has_avx2_vaes, "avx2", "vaes");
if has_avx2_vaes::get() {
    return /* .. */;
}

cpufeatures::new!(has_aes_sse41, "aes", "sse4.1");
if has_aes_sse41::get() {
    return /* .. */;
}

// Fallback

It'd be great to have something that can replace multiple individual atomic reads with a single one in such cases.

The shape of cfg_select! seems perfect for this.

Dominant language
Rust
Stars
674
Forks
170
Avg merge
1d 12h
Merged PRs (30d)
10

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