[6.1] AliasAnalysis: consider memory effects of a consume/destroy of a class on it's let-fields #78792
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Contributor
eeckstein
commented
Jan 21, 2025
eeckstein
commented
- Explanation: Fixes a bug in alias-analysis which can cause a mis-compile by moving a release of an object before the load of a let-field. Although a let-field can never be mutated, a release or consume of the class must be considered as writing to such a field.
- Risk: Low. It's a small change which makes alias-analysis more conservative.
- Testing: Tested by a lit test.
- Issue: rdar://142996449
- Reviewer: @meg-gupta
- Main branch PR: AliasAnalysis: consider memory effects of a consume/destroy of a class on it's let-fields #78754. Note that this only cherry-picks the essential bug-fix commit to reduce the risk.
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tbkka
approved these changes
Jan 21, 2025
…s on it's let-fields Although a let-field can never be mutated, a release or consume of the class must be considered as writing to such a field. This change removes the special handling of let-fields in two places, where they don't belong. Class fields are handled by ImmutableScope anyway. Handling of global let-variable is temporarily removed by this commit. Fixes a miscompile. rdar://142996449
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