Fix missing GC root in the presence of try/catch #22516
Merged
Conversation
This file contains 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
Since try/catch (returns_twice at the LLVM level) can have control flow edges not visible to LLVM, we need to be very conservative here. In order to fix correctness, simply make sure that a value that is live across a sigsetjmp gets frozen in its own dedicated GC slot. There's fancier schemes we could attempt, but they would rely on expressing the exception edges in LLVM IR in one way or another.
vtjnash
approved these changes
Jun 25, 2017
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Outdated suggestions cannot be applied.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.
Since try/catch (returns_twice at the LLVM level) can have control flow
edges not visible to LLVM, we need to be very conservative here. In
order to fix correctness, simply make sure that a value that is live
across a sigsetjmp gets frozen in its own dedicated GC slot. There's
fancier schemes we could attempt, but they would rely on expressing
the exception edges in LLVM IR in one way or another.