Struct LivenessContext

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struct LivenessContext<'a, 'typeck, 'tcx> {
    typeck: &'a mut TypeChecker<'typeck, 'tcx>,
    location_map: &'a DenseLocationMap,
    move_data: &'a MoveData<'tcx>,
    drop_data: FxIndexMap<Ty<'tcx>, DropData<'tcx>>,
    flow_inits: Option<ResultsCursor<'a, 'tcx, MaybeInitializedPlaces<'a, 'tcx>>>,
    local_use_map: &'a LocalUseMap,
}
Expand description

Contextual state for the type-liveness coroutine.

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§typeck: &'a mut TypeChecker<'typeck, 'tcx>

Current type-checker, giving us our inference context etc.

This also stores the body we’re currently analyzing.

§location_map: &'a DenseLocationMap

Defines the PointIndex mapping

§move_data: &'a MoveData<'tcx>

Mapping to/from the various indices used for initialization tracking.

§drop_data: FxIndexMap<Ty<'tcx>, DropData<'tcx>>

Cache for the results of dropck_outlives query.

§flow_inits: Option<ResultsCursor<'a, 'tcx, MaybeInitializedPlaces<'a, 'tcx>>>

Results of dataflow tracking which variables (and paths) have been initialized. Computed lazily when needed by drop-liveness.

§local_use_map: &'a LocalUseMap

Index indicating where each variable is assigned, used, or dropped.

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impl<'a, 'typeck, 'tcx> LivenessContext<'a, 'typeck, 'tcx>

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fn flow_inits( &mut self, ) -> &mut ResultsCursor<'a, 'tcx, MaybeInitializedPlaces<'a, 'tcx>>

Computes the MaybeInitializedPlaces dataflow analysis if it hasn’t been done already.

In practice, the results of this dataflow analysis are rarely needed but can be expensive to compute on big functions, so we compute them lazily as a fast path when:

  • there are relevant live locals
  • there are drop points for these relevant live locals.

This happens as part of the drop-liveness computation: it’s the only place checking for maybe-initializedness of MovePathIndexes.

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impl<'tcx> LivenessContext<'_, '_, 'tcx>

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fn body(&self) -> &Body<'tcx>

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fn initialized_at_curr_loc(&mut self, mpi: MovePathIndex) -> bool

Returns true if the local variable (or some part of it) is initialized at the current cursor position. Callers should call one of the seek methods immediately before to point the cursor to the desired location.

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fn initialized_at_terminator( &mut self, block: BasicBlock, mpi: MovePathIndex, ) -> bool

Returns true if the local variable (or some part of it) is initialized in the terminator of block. We need to check this to determine if a DROP of some local variable will have an effect – note that drops, as they may unwind, are always terminators.

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fn initialized_at_exit(&mut self, block: BasicBlock, mpi: MovePathIndex) -> bool

Returns true if the path mpi (or some part of it) is initialized at the exit of block.

Warning: Does not account for the result of Call instructions.

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fn add_use_live_facts_for( &mut self, value: Ty<'tcx>, live_at: &IntervalSet<PointIndex>, )

Stores the result that all regions in value are live for the points live_at.

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fn add_drop_live_facts_for( &mut self, dropped_local: Local, dropped_ty: Ty<'tcx>, drop_locations: &[Location], live_at: &IntervalSet<PointIndex>, )

Some variable with type live_ty is “drop live” at location – i.e., it may be dropped later. This means that some of the regions in its type must be live at location. The precise set will depend on the dropck constraints, and in particular this takes #[may_dangle] into account.

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fn make_all_regions_live( location_map: &DenseLocationMap, typeck: &mut TypeChecker<'_, 'tcx>, value: impl TypeVisitable<TyCtxt<'tcx>> + Relate<TyCtxt<'tcx>>, live_at: &IntervalSet<PointIndex>, )

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fn compute_drop_data( typeck: &TypeChecker<'_, 'tcx>, dropped_ty: Ty<'tcx>, span: Span, ) -> DropData<'tcx>

Auto Trait Implementations§

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impl<'a, 'typeck, 'tcx> !DynSend for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> !DynSync for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> Freeze for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> !RefUnwindSafe for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> !Send for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> !Sync for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> Unpin for LivenessContext<'a, 'typeck, 'tcx>

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impl<'a, 'typeck, 'tcx> !UnwindSafe for LivenessContext<'a, 'typeck, 'tcx>

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impl<T> Aligned for T

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const ALIGN: Alignment

Alignment of Self.
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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

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fn collect_and_apply<I, F>(iter: I, f: F) -> R
where I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to f(&iter.collect::<Vec<_>>()).

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type Output = R

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fn filterable( self, filter_name: &'static str, ) -> RequestFilterDataProvider<T, fn(DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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type Error = !

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const ALIGN: usize

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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Dereferences the given pointer. Read more
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type Error = <U as TryFrom<T>>::Error

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Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 224 bytes