Fix DoesValueTypeContainGCRefs in the interpreter #121846
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There was a mistake in the implementation that prevented it from working correctly in some cases. The return value of the getClassSize() is not a number of slots filled in the array, but a number of GC references in the array. So if there were e.g. three slots and there was one GC reference in the second slot, the DoesValueTypeContainGCRefs returned false.
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Tagging subscribers to this area: @BrzVlad, @janvorli, @kg |
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janvorli
November 20, 2025 16:13
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Pull Request Overview
This PR fixes a critical bug in the DoesValueTypeContainGCRefs function in the CoreCLR interpreter. The function incorrectly interpreted the return value of getClassGClayout(), treating it as the number of slots to iterate through, when it actually represents the total count of GC references found in the type.
- Corrected the logic by directly using the return value of
getClassGClayout()to determine if GC references exist - Renamed the variable from
numSlotstonumGCRefsto accurately reflect its meaning - Simplified the implementation by removing the unnecessary loop
kg
approved these changes
Nov 20, 2025
BrzVlad
approved these changes
Nov 20, 2025
davidwrighton
approved these changes
Nov 20, 2025
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There was a mistake in the implementation that prevented it from working correctly in some cases. The return value of the getClassSize() is not a number of slots filled in the array, but a number of GC references in the array. So if there were e.g. three slots and there was one GC reference in the second slot, the DoesValueTypeContainGCRefs returned false.