MemoryLifetime: fix a problem where DestroyHoisting moved a destroy_addr before a use of a trivial type. #27117
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…ddr before a use of a trivial type. Even if a destroy_addr of a trivial type is a no-op, we must not end up with using such a value after a destroy_addr. The fix is to also handle aggregate fields of trivial types in MemoryLifetime. rdar://problem/55125020
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@swift-ci test |
atrick
reviewed
Sep 13, 2019
| @@ -73,6 +73,17 @@ static bool allUsesInSameBlock(AllocStackInst *ASI) { | |||
| return numDeallocStacks == 1; | |||
| } | |||
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| static bool shouldTrackLocation(SILType ty, SILFunction *function) { | |||
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Do you anticipate using function eventually?
| // case of enums, e.g. store of Optional.none to an Optional<T> where T | ||
| // is not trivial. | ||
| // In such a case it can happen that the Optional<T> is not destoyed. | ||
| // We currently cannot handle such patterns. |
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This code checks for storing a nontrivial type into a trivial memory location. The comments seem to say the opposite. Is that a mistake or my misunderstanding? Can you add a unit test for this special case (and the inverse case if that's also a problem)? I don't understand why this needs to be a bailout rather than just tracking this location as trivial so the full nontrivial constraints aren't applied.
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Even if a destroy_addr of a trivial type is a no-op, we must not end up with using such a value after a destroy_addr.
The fix is to also handle aggregate fields of trivial types in MemoryLifetime.
rdar://problem/55125020