Fix MandatoryARCOpts tryJoiningCopyValueLiveRangeWithOperand. #64836
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Fix a miscompile in Debug builds at -Onone. This optimization ignores uses of owned values that aren't enclosed in borrow scopes. This is fairly eggregious since project_box instructions are never borrowed, which means that all local variables have this problem. This is a well-known issue that occurs throughout OSSA optimizations. The reason that we don't see the problem often is that the optimizations are hidden behind a pile of ad-hoc pattern matching, so they only kick in for simple cases. This approach to optimization is great at hiding problems for a long time. We're attempting to design away this class of problems in the next release. Until then, it's one miscompile at a time. Fixes rdar://107420448 (Variable mutation in block isn't reflected in outer scope: new behavior in swift 5.9)
|
@swift-ci test |
|
@swift-ci benchmark |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fix a miscompile in Debug builds at -Onone.
This optimization ignores uses of owned values that aren't enclosed in borrow scopes. This is fairly eggregious since project_box instructions are never borrowed, which means that all local variables have this problem.
This is a well-known issue that occurs throughout OSSA optimizations. The reason that we don't see the problem often is that the optimizations are hidden behind a pile of ad-hoc pattern matching, so they only kick in for simple cases. This approach to optimization is great at hiding problems for a long time.
We're attempting to design away this class of problems in the next release. Until then, it's one miscompile at a time.
Fixes rdar://107420448 (Variable mutation in block isn't reflected in outer scope: new behavior in swift 5.9)