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[6.1] TypeLowering: assume that C unions can contain a pointer #78232

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Merged
merged 1 commit into from
Dec 18, 2024
Merged

[6.1] TypeLowering: assume that C unions can contain a pointer #78232

merged 1 commit into from
Dec 18, 2024

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eeckstein
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  • Explanation: Fixes a miscompile caused by C unions containing a pointer. C unions are imported as opaque types. Therefore we have to assume that a union contains a pointer. This is important for alias analysis to catch escaping pointers via C unions.
  • Risk: Low. It is a simple change which makes alias analysis more conservative for C unions.
  • Testing: Tested by a test case.
  • Issue: rdar://141555290
  • Reviewer: @jckarter
  • Main branch PR: TypeLowering: assume that C unions can contain a pointer #78221

@eeckstein eeckstein requested a review from a team as a code owner December 17, 2024 07:38
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@swift-ci test

@eeckstein eeckstein requested a review from jckarter December 17, 2024 07:39
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@swift-ci test macos windows

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@swift-ci test

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@swift-ci test

@eeckstein
TypeLowering: assume that C unions can contain a pointer
a19b6b8 
C unions are imported as opaque types. Therefore we have to assume that a union contains a pointer.
This is important for alias analysis to catch escaping pointers via C unions.

Fixes a miscompile.
rdar://141555290
@eeckstein eeckstein force-pushed the pointers-in-c-unions-6.1 branch from 766d2d6 to a19b6b8 Compare December 17, 2024 13:38
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@swift-ci test

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@swift-ci test windows

@eeckstein eeckstein merged commit f3fe377 into release/6.1 Dec 18, 2024
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@eeckstein eeckstein deleted the pointers-in-c-unions-6.1 branch December 18, 2024 05:38
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@tbkka tbkka tbkka approved these changes

@jckarter jckarter Awaiting requested review from jckarter

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@eeckstein @tbkka