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> Analysis<'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.

fn apply_statement_effect( &mut self, trans: &mut Self::Domain, stmt: &Statement<'tcx>, location: Location, )

Updates the current dataflow state with the effect of evaluating a statement.

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

Updates the current dataflow state with the effect of evaluating a terminator.

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

Updates the current dataflow state with the effect of a successful return from a Call terminator.

type Direction = Forward

The direction of this analysis. Either Forward or Backward.

fn apply_before_statement_effect( &mut self, _state: &mut Self::Domain, _statement: &Statement<'tcx>, _location: Location, )

Updates the current dataflow state with an effect that occurs immediately before the given statement.

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

Updates the current dataflow state with an effect that occurs immediately before the given terminator.

fn apply_switch_int_edge_effects( &mut self, _block: BasicBlock, _discr: &Operand<'tcx>, _apply_edge_effects: &mut impl SwitchIntEdgeEffects<Self::Domain>, )

Updates the current dataflow state with the effect of taking a particular branch in a SwitchInt terminator.

fn into_engine<'mir>( self, tcx: TyCtxt<'tcx>, body: &'mir Body<'tcx>, ) -> Engine<'mir, 'tcx, Self>

where Self: Sized,

Creates an Engine to find the fixpoint for this dataflow problem.

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