[6.2 🍒] Fix ownership issues with sequences of partial_apply's in AutoDiff closure specialization pass #81240
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Fix ownership issues with sequences of partial_apply's in AutoDiff closure specialization pass (swiftlang#80662) Each partial_apply consumes its arguments, therefore we should never release intermediate ones in the sequence of closures. Fixes swiftlang#78847 (cherry picked from commit 87ca0f8)
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@swift-ci please test |
DougGregor
approved these changes
May 1, 2025
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Explanation:
Fix ownership issues with sequences of partial_apply's in AutoDiff closure specialization pass (Fix ownership issues with sequences of partial_apply's in AutoDiff closure specialization pass #80662)
Each partial_apply consumes its arguments, therefore we should never release intermediate ones in the sequence of closures.
(cherry picked from commit 87ca0f8)
Scope:
The workaround for the original issue caused a severe performance regression in AutoDiff performance because it disabled the closure specialization pass in the AutoDiff case. This fix and the removal of the workaround restores performance back to the expected levels.
Issues:
The AutodiffClosureSpecialization pass creates SIL with invalid ownership when enabling OSSA modules #78847
Original PRs:
Fix ownership issues with sequences of partial_apply's in AutoDiff closure specialization pass #80662
Risk:
Low. Resolves the underlying issue in the closure specialization pass, and restores performance for the AutoDiff case.
Testing:
A test case has been added to exercise this optimization path.
Reviewers:
@asl @eeckstein