microsoft / microsoft/STL

`<bit>`: Investigate Clang's new intrinsics for bit operations

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performance
Dominant language
C++
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Description

Clang 19 has these new generic intrinsics which are possibly useful for <bit>:

  • __builtin_ctzg
  • __builtin_clzg
  • __builtin_popcountg

It seems that they are at least beneficial for throughput, but we should also investigate their performance impact.

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at the implementation and inspect how the existing bit-operation entry points could use Clang 19's __builtin_ctzg, __builtin_clzg, and __builtin_popcountg. Measure their throughput impact and document whether the intrinsics are beneficial; the issue names no specific files or tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
performance
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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