Struct rustc_mir_dataflow::impls::EverInitializedPlaces

pub struct EverInitializedPlaces<'a, 'tcx> {
    tcx: TyCtxt<'tcx>,
    body: &'a Body<'tcx>,
    mdpe: &'a MoveDataParamEnv<'tcx>,
}

EverInitializedPlaces tracks all places that might have ever been initialized upon reaching a particular point in the control flow for a function, without an intervening StorageDead.

This dataflow is used to determine if an immutable local variable may be assigned to.

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

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

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

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

    }                                       // {a, b,    d }

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

Fields

tcx: TyCtxt<'tcx>

body: &'a Body<'tcx>

mdpe: &'a MoveDataParamEnv<'tcx>

Implementations

impl<'a, 'tcx> EverInitializedPlaces<'a, 'tcx>

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

Trait Implementations

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

type Domain = ChunkedBitSet<InitIndex>

The type that holds the dataflow state at any given point in the program.

const NAME: &'static str = "ever_init"

A descriptive name for this analysis. Used only for debugging.

fn bottom_value(&self, _: &Body<'tcx>) -> Self::Domain

Returns the initial value of the dataflow state upon entry to each basic block.

fn initialize_start_block(&self, body: &Body<'tcx>, state: &mut Self::Domain)

Mutates the initial value of the dataflow state upon entry to the START_BLOCK.

type Direction = Forward

The direction of this analysis. Either Forward or Backward.

impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, 'tcx>

type Idx = InitIndex

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

See Analysis::apply_statement_effect.

fn terminator_effect(
    &self,
    trans: &mut impl GenKill<Self::Idx>,
    _terminator: &Terminator<'tcx>,
    location: Location
)

See Analysis::apply_terminator_effect.

fn call_return_effect(
    &self,
    trans: &mut impl GenKill<Self::Idx>,
    block: BasicBlock,
    _return_places: CallReturnPlaces<'_, 'tcx>
)

See Analysis::apply_call_return_effect.

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

See Analysis::apply_before_statement_effect.

fn before_terminator_effect(
    &self,
    _trans: &mut impl GenKill<Self::Idx>,
    _terminator: &Terminator<'tcx>,
    _location: Location
)

See Analysis::apply_before_terminator_effect.

fn yield_resume_effect(
    &self,
    _trans: &mut impl GenKill<Self::Idx>,
    _resume_block: BasicBlock,
    _resume_place: Place<'tcx>
)

See Analysis::apply_yield_resume_effect.

fn switch_int_edge_effects<G: GenKill<Self::Idx>>(
    &self,
    _block: BasicBlock,
    _discr: &Operand<'tcx>,
    _edge_effects: &mut impl SwitchIntEdgeEffects<G>
)

See Analysis::apply_switch_int_edge_effects.

impl<'a, 'tcx> HasMoveData<'tcx> for EverInitializedPlaces<'a, 'tcx>

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

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: 24 bytes