[6.2][Concurrency] Correct memory effect attributes of task_create #82180
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Without this, llvm would sometimes wrongly assume there's no indirect accesses and the optimizations can lead to a runtime crash, by optimizing away initializing options properly. Resolves rdar://152548190
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@swift-ci please test |
hborla
approved these changes
Jun 12, 2025
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Description: Without this, llvm would sometimes wrongly assume there's no indirect
accesses and the optimizations can lead to a runtime crash, by optimizing away initializing options properly.
Scope/Impact: Users of some apis which have multiple task options can experience crashes; This only manifested on some startSynchronously legacy API users so far but this is purely accidental -- it seems other APIs were just "lucky" (for years), since the functions were AEIC.
Risk: Low, corrects memory semantics annotation to prevent too aggressive optimizations.
Testing: Added test which triggered the miscompile.
Reviewed by: @mikeash @fhahn @rjmccall
Original PR: #82179
Radar: rdar://152548190