Remove subkinds from value slots #3981
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lthls
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May 13, 2025
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This patch has the following negative consequences:
- All value slots of kind
Value, including immediates, are now stored in the scannable part of the closure - All value slots of kind
Value, for large closures and static closures, will be initialised usingcaml_initialize. For immediates, before this PR a direct write could be used. - In some very uncommon cases, when simplifying a value slot projection the flambda2 type for the result will be less precise than it was before.
These are expected consequences, and I am in favour of merging this PR now to allow progress on unboxing of free variables, and work on restoring the lost functionality in a later PR (at least the first two points; the third one is likely irrelevant).
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I'm not sure actually. How much work is it to restore the old behaviour for immediates here? |
lthls
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When the reaper replaces some values by poison, the subkind information in value slots can become incorrect. This fixes the problem by completely removing the subkind information in value slots, which is otherwise only used for putting tagged immediates in the non-scanned area of closures.