<xutility>: Drop `memset` optimization?
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Description
While working on #3641 I've noticed that the compiler currently does the optimizations on its own most of the time for 1 and 2 byte elements.
The exception I found is a case with zero value and global variable, see DevCom-10334032.
But otherwise the optimization is there - either vectorized implementation, or rep stos or memset call.
However, the optimization is not engaged for larger types, specifically 4 and 8 bytes, except for compile-time zero.
For compile-time zero, compiler substitutes memset on its own.
I'm not sure how to proceed:
- Should we close #3641 without merging ?
- Should we add 4 and 8 byte types
std::filloptimization ? - Should we drop 1 byte
memsetoptimization ?
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 by reviewing #3641 and the compiler behavior described in DevCom-10334032, comparing the 1-, 2-, 4-, and 8-byte cases mentioned here. Done requires a maintainer decision on whether to close #3641, extend the std::fill optimization, or remove the 1-byte memset optimization; no files or tests are named.
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
- Needs clarification
- Newbie friendliness
- 25/100