🍒[cxx-interop] Fix memory layout for structs with out-of-order base types #78237
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
In C++, a primary base class that is placed in the beginning of the type's memory layout isn't always the type that is the first in the list of bases – the base types might be laid out in memory in a different order. This makes sure that IRGen handles base types of C++ structs in the correct order. This fixes an assertion in asserts-enabled compilers, and an out-of-memory error in asserts-disabled compilers. The issue was happening for both value types and foreign reference types. This change also includes a small refactoring to reuse the logic between the two code paths. rdar://140848603 (cherry picked from commit 57c7ecd)
|
@swift-ci please test |
Xazax-hun
approved these changes
Dec 17, 2024
DougGregor
approved these changes
Dec 17, 2024
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Outdated suggestions cannot be applied.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.
Explanation: In C++, a primary base class that is placed in the beginning of the type's memory layout isn't always the type that is the first in the list of bases – the base types might be laid out in memory in a different order.
This change makes sure that IRGen handles base types of C++ structs in the correct order.
Scope: This fixes an assertion in asserts-enabled compilers, and an out-of-memory error in asserts-disabled compilers. The issue was happening for both value types and foreign reference types. This change also includes a small refactoring to reuse the logic between the two code paths.
Risk: Low, this only applies to C++ structs, and the behavior is only altered for structs with multiple inheritance.
Testing: Added compiler tests.
Issue: rdar://140848603
Reviewer: @rjmccall @j-hui @Xazax-hun
Original PR: #78166