`wmemchr` optimization and its throughput impact
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- Dominant language
- C++
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Description
This include:
https://github.com/microsoft/STL/blob/313964b78a8fd5a52e7965e13781f735bcce13c5/stl/inc/xutility#L15
Is used for wmemchr optimization, it was introcuded in 2024.
The <cwchar> brings in <intrin.h>, which we have always been avoided for throughput reasons. Probably it started bringing it in specifically for wmemchr optimization.
What should we do now? I see three opposite paths forward:
- Drop
#include <cwchar>and currentwmemchroptimizations. Almost no impact asvector_algorithms.cppis preferred most of the time anyway. - Get SDK fixed to use
<intrin0.h>. - Do nothing, accept throughput impact.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the referenced include in stl/inc/xutility around line 15 and inspect how brings in <intrin.h> for wmemchr. Compare its impact with vector_algorithms.cpp and investigate the SDK's possible use of <intrin0.h>. Done means choosing and documenting one of the three proposed paths based on throughput impact.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- performance
- Issue type
- Refactor
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100