Move type checks from switch cases to beginning of `_Py_Specialize_BinaryOp`
Nobody has claimed this yet.
- Dominant language
- Python
- Stars
- 77.2k
- Forks
- 35.9k
- PR merge metrics
- PR metrics pending
Description
Feature or enhancement
Proposal:
_Py_Specialize_BinaryOp: https://github.com/python/cpython/blob/aeb9b65aa26444529e4adc7d6e5b0d3dd9889ec2/Python/specialize.c#L2380-L2443
uses
if (!Py_IS_TYPE(lhs, Py_TYPE(rhs))) {
break;
}
check inside every switch case which is redundant. Placing this check before switch results in same performance but less generated code. Compiler with -O3 option seems to not recognize it. Attaching generated machine code (clang, apple silicon) for old and new versions
new.txt
old.txt
Feel free to close this if not worth it.
Has this already been discussed elsewhere?
No response given
Links to previous discussion of this feature:
No response
Linked PRs
- gh-128311
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
Check gh-128311 first, since the issue links work already in progress. Then read Python/specialize.c at _Py_Specialize_BinaryOp and compare the attached old.txt and new.txt compiler output; done means the redundant checks are handled consistently and the generated code has the intended result.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c
- Domain
- compilers, performance
- Issue type
- Feature
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 25/100