Struct rustc_mir_dataflow::impls::MaybeInitializedPlaces

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pub struct MaybeInitializedPlaces<'a, 'tcx> {
    tcx: TyCtxt<'tcx>,
    body: &'a Body<'tcx>,
    mdpe: &'a MoveDataParamEnv<'tcx>,
    skip_unreachable_unwind: bool,
}
Expand description

MaybeInitializedPlaces tracks all places that might be initialized upon reaching a particular point in the control flow for a function.

For example, in code like the following, we have corresponding dataflow information shown in the right-hand comments.

struct S;
fn foo(pred: bool) {                        // maybe-init:
                                            // {}
    let a = S; let mut b = S; let c; let d; // {a, b}

    if pred {
        drop(a);                            // {   b}
        b = S;                              // {   b}

    } else {
        drop(b);                            // {a}
        d = S;                              // {a,       d}

    }                                       // {a, b,    d}

    c = S;                                  // {a, b, c, d}
}

To determine whether a place must be initialized at a particular control-flow point, one can take the set-difference between this data and the data from MaybeUninitializedPlaces at the corresponding control-flow point.

Similarly, at a given drop statement, the set-intersection between this data and MaybeUninitializedPlaces yields the set of places that would require a dynamic drop-flag at that statement.

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§tcx: TyCtxt<'tcx>§body: &'a Body<'tcx>§mdpe: &'a MoveDataParamEnv<'tcx>§skip_unreachable_unwind: bool

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impl<'a, 'tcx> MaybeInitializedPlaces<'a, 'tcx>

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pub fn new( tcx: TyCtxt<'tcx>, body: &'a Body<'tcx>, mdpe: &'a MoveDataParamEnv<'tcx> ) -> Self

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pub fn skipping_unreachable_unwind(self) -> Self

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pub fn is_unwind_dead( &self, place: Place<'tcx>, state: &MaybeReachable<ChunkedBitSet<MovePathIndex>> ) -> bool

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impl<'a, 'tcx> MaybeInitializedPlaces<'a, 'tcx>

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fn update_bits( trans: &mut impl GenKill<MovePathIndex>, path: MovePathIndex, state: DropFlagState )

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impl<'tcx> AnalysisDomain<'tcx> for MaybeInitializedPlaces<'_, 'tcx>

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type Domain = MaybeReachable<ChunkedBitSet<MovePathIndex>>

There can be many more MovePathIndex than there are locals in a MIR body. We use a chunked bitset to avoid paying too high a memory footprint.

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const NAME: &'static str = "maybe_init"

A descriptive name for this analysis. Used only for debugging. Read more
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fn bottom_value(&self, _: &Body<'tcx>) -> Self::Domain

Returns the initial value of the dataflow state upon entry to each basic block.
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fn initialize_start_block(&self, _: &Body<'tcx>, state: &mut Self::Domain)

Mutates the initial value of the dataflow state upon entry to the START_BLOCK. Read more
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type Direction = Forward

The direction of this analysis. Either Forward or Backward.
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impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, 'tcx>

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type Idx = MovePathIndex

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fn domain_size(&self, _: &Body<'tcx>) -> usize

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fn statement_effect( &mut self, trans: &mut impl GenKill<Self::Idx>, statement: &Statement<'tcx>, location: Location )

See Analysis::apply_statement_effect. Note how the second arg differs.
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fn terminator_effect<'mir>( &mut self, state: &mut Self::Domain, terminator: &'mir Terminator<'tcx>, location: Location ) -> TerminatorEdges<'mir, 'tcx>

See Analysis::apply_terminator_effect.
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fn call_return_effect( &mut self, trans: &mut Self::Domain, _block: BasicBlock, return_places: CallReturnPlaces<'_, 'tcx> )

See Analysis::apply_call_return_effect.
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fn switch_int_edge_effects<G: GenKill<Self::Idx>>( &mut self, block: BasicBlock, discr: &Operand<'tcx>, edge_effects: &mut impl SwitchIntEdgeEffects<G> )

See Analysis::apply_switch_int_edge_effects.
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fn before_statement_effect( &mut self, _trans: &mut impl GenKill<Self::Idx>, _statement: &Statement<'tcx>, _location: Location )

See Analysis::apply_before_statement_effect. Note how the second arg differs.
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fn before_terminator_effect( &mut self, _trans: &mut Self::Domain, _terminator: &Terminator<'tcx>, _location: Location )

See Analysis::apply_before_terminator_effect.
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impl<'a, 'tcx> HasMoveData<'tcx> for MaybeInitializedPlaces<'a, 'tcx>

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fn move_data(&self) -> &MoveData<'tcx>

Auto Trait Implementations§

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impl<'a, 'tcx> DynSend for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> DynSync for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> Freeze for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> !RefUnwindSafe for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> !Send for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> !Sync for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> Unpin for MaybeInitializedPlaces<'a, 'tcx>

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impl<'a, 'tcx> !UnwindSafe for MaybeInitializedPlaces<'a, '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

Mutably borrows from an owned value. Read more
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impl<T, R> CollectAndApply<T, R> for 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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Returns the argument unchanged.

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fn instrument(self, span: Span) -> Instrumented<Self>

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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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impl<P> IntoQueryParam<P> for P

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impl<T> MaybeResult<T> for T

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type Error = !

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fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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impl<T> Pointable for T

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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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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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Should always be Self
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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: 32 bytes