Struct EverInitializedPlaces

pub struct EverInitializedPlaces<'a, 'tcx> {
    body: &'a Body<'tcx>,
    move_data: &'a MoveData<'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

body: &'a Body<'tcx>

move_data: &'a MoveData<'tcx>

Implementations

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

pub fn new(body: &'a Body<'tcx>, move_data: &'a MoveData<'tcx>) -> Self

Trait Implementations

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

type Domain = ChunkedBitSet<InitIndex>

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

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

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

See Analysis::apply_statement_effect. Note how the second arg differs.

fn terminator_effect<'mir>( &mut self, trans: &mut Self::Domain, terminator: &'mir Terminator<'tcx>, location: Location, ) -> TerminatorEdges<'mir, 'tcx>

See Analysis::apply_terminator_effect.

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

See Analysis::apply_call_return_effect.

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.

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

See Analysis::apply_before_terminator_effect.

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.

impl<'tcx> HasMoveData<'tcx> for EverInitializedPlaces<'_, '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: 16 bytes