Prereq1 for async drop - drop & async_fut fields in Drop terminator
#129734
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Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt Some changes occurred in compiler/rustc_codegen_cranelift cc @bjorn3 Some changes occurred to the CTFE / Miri engine cc @rust-lang/miri This PR changes MIR cc @oli-obk, @RalfJung, @JakobDegen, @davidtwco, @celinval, @vakaras |
| /// StateTransform pass. In `expand_async_drops` async drops are expanded | ||
| /// into one or two yield points with poll ready/pending switch. | ||
| /// When a coroutine has any internal async drop, the coroutine drop function will be async | ||
| /// (generated by `create_coroutine_drop_shim_async`, not `create_coroutine_drop_shim`). |
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It might be worth also discussing async drop in the MirPhase docs. And if any new MIR phase restrictions are added, please make sure to update the MIR validator.
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Comment about async drops added in MirPhase:
/// - Async drops: after drop elaboration some drops may become async (`drop`, `async_fut` fields).
/// StateTransform pass will expand those async drops or reset to sync.
Could you, pls, be more specific about "update the MIR validator"? Async drop terminators live from ElaborateDrops to StateTransform pass in transition to MirPhase::Runtime(..). What MIR validator changes do you recommend?
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☔ The latest upstream changes (presumably #130724) made this pull request unmergeable. Please resolve the merge conflicts. |
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r? @nikomatsakis is going to look into this |
This is subpart 1 PR of #123948, just for review purposes.
Added Option
dropandasync_futfields in Drop terminator for use when Drop terminator is async drop.dropfield has the same meaning asdropfield in Yield terminator. We need it because async drop is a hidden Yield, expanded into yield-point in StateTransform (later commits).async_futcontains local for async drop future, generated byasync_fut = async_drop_in_place(droppee)in drop elaboration (later commits).