[swift-vfe] Disable for @objc classes #69434
Merged
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
Swift methods can be called from Objective-C without a vtable load, and more importantly without emitting an `llvm.type.checked.load` instruction. These are effectively virtual callsites that are not visible to the VFE logic in GlobalDCE. To to safely enable swift-vfe we must prevent vtables whose functions are callable from Objective-C from being eliminated. To do this we ensure such vtables have public vcall_visibility, which indirectly prevents GlobalDCE from stripping them.
|
@swift-ci Please test |
kubamracek
approved these changes
Oct 27, 2023
|
Thanks! |
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Outdated suggestions cannot be applied.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.
Swift methods can be called from Objective-C without a vtable load, and more importantly without emitting an
llvm.type.checked.loadinstruction. These are effectively virtual callsites that are not visible to the VFE logic in GlobalDCE.To to safely enable swift-vfe we must prevent vtables whose functions are callable from Objective-C from being eliminated.
To do this we ensure such vtables have public vcall_visibility, which indirectly prevents GlobalDCE from stripping them.