Replace opened Pack Element types with the concrete type of the element when it is statically known#88591
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aidan-hall wants to merge 6 commits intoswiftlang:mainfrom
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Replace opened Pack Element types with the concrete type of the element when it is statically known#88591aidan-hall wants to merge 6 commits intoswiftlang:mainfrom
aidan-hall wants to merge 6 commits intoswiftlang:mainfrom
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Note that we have made GenericEnvironment::getOpenedPackParams public.
In some scenarios, it is possible to statically determine which element of a pack a pack indexing instruction will access.
LocalArchetype is the shared base class of ArchetypeType (which SimplifyApply previously worked with) and ElementArchetypeType (@pack_element() types). This allows us to specialize calls to generic functions inside "repeat ... each" expressions and loops within specialized variadic generic functions.
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Explanation
When using a
@pack_elementtype to refer to an element of a concrete pack type at a compile-time-known index, we can replace the@pack_elementwith the concrete type of the element at that index.witness_methodallows us to replace the witness table lookup and call with a direct call to the witness function for the concrete type.applymakes it possible to specialize calls to generic functions inside loops over pack elements.This is intended to be a smaller version of the changes proposed in #85333, and has limitations on what it can handle (e.g. it can only get the concrete pack type for
open_pack_elementinstructions that open a single pack type). Nonetheless, it enables more effective optimisations in many cases.Scope
TODO
Issues
rdar://163046681 (at least partially)
Risk
TODO
Testing
TODO