Struct rustc_mir_dataflow::impls::MaybeUninitializedPlaces
source · [−]pub struct MaybeUninitializedPlaces<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
body: &'a Body<'tcx>,
mdpe: &'a MoveDataParamEnv<'tcx>,
mark_inactive_variants_as_uninit: bool,
}
Expand description
MaybeUninitializedPlaces
tracks all places that might be
uninitialized 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-uninit:
// {a, b, c, d}
let a = S; let mut b = S; let c; let d; // { c, d}
if pred {
drop(a); // {a, c, d}
b = S; // {a, c, d}
} else {
drop(b); // { b, c, d}
d = S; // { b, c }
} // {a, b, c, d}
c = S; // {a, b, d}
}
To determine whether a place must be uninitialized at a
particular control-flow point, one can take the set-difference
between this data and the data from MaybeInitializedPlaces
at the
corresponding control-flow point.
Similarly, at a given drop
statement, the set-intersection
between this data and MaybeInitializedPlaces
yields the set of
places that would require a dynamic drop-flag at that statement.
Fields
tcx: TyCtxt<'tcx>
body: &'a Body<'tcx>
mdpe: &'a MoveDataParamEnv<'tcx>
mark_inactive_variants_as_uninit: bool
Implementations
sourceimpl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>
impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>
pub fn new(
tcx: TyCtxt<'tcx>,
body: &'a Body<'tcx>,
mdpe: &'a MoveDataParamEnv<'tcx>
) -> Self
sourcepub fn mark_inactive_variants_as_uninit(self) -> Self
pub fn mark_inactive_variants_as_uninit(self) -> Self
Causes inactive enum variants to be marked as “maybe uninitialized” after a switch on an enum discriminant.
This is correct in a vacuum but is not the default because it causes problems in the borrow
checker, where this information gets propagated along FakeEdge
s.
sourceimpl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>
impl<'a, 'tcx> MaybeUninitializedPlaces<'a, 'tcx>
fn update_bits(
trans: &mut impl GenKill<MovePathIndex>,
path: MovePathIndex,
state: DropFlagState
)
Trait Implementations
sourceimpl<'tcx> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>
impl<'tcx> AnalysisDomain<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>
type Domain = ChunkedBitSet<MovePathIndex>
type Domain = ChunkedBitSet<MovePathIndex>
The type that holds the dataflow state at any given point in the program.
sourceconst NAME: &'static str = "maybe_uninit"
const NAME: &'static str = "maybe_uninit"
A descriptive name for this analysis. Used only for debugging. Read more
sourcefn bottom_value(&self, _: &Body<'tcx>) -> Self::Domain
fn bottom_value(&self, _: &Body<'tcx>) -> Self::Domain
The initial value of the dataflow state upon entry to each basic block.
sourcefn initialize_start_block(&self, _: &Body<'tcx>, state: &mut Self::Domain)
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
sourceimpl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>
impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx>
type Idx = MovePathIndex
sourcefn statement_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_statement: &Statement<'tcx>,
location: Location
)
fn statement_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_statement: &Statement<'tcx>,
location: Location
)
See Analysis::apply_statement_effect
.
sourcefn terminator_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_terminator: &Terminator<'tcx>,
location: Location
)
fn terminator_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_terminator: &Terminator<'tcx>,
location: Location
)
See Analysis::apply_terminator_effect
.
sourcefn call_return_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_block: BasicBlock,
return_places: CallReturnPlaces<'_, 'tcx>
)
fn call_return_effect(
&self,
trans: &mut impl GenKill<Self::Idx>,
_block: BasicBlock,
return_places: CallReturnPlaces<'_, 'tcx>
)
See Analysis::apply_call_return_effect
.
sourcefn switch_int_edge_effects<G: GenKill<Self::Idx>>(
&self,
block: BasicBlock,
discr: &Operand<'tcx>,
edge_effects: &mut impl SwitchIntEdgeEffects<G>
)
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
.
sourcefn before_statement_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_statement: &Statement<'tcx>,
_location: Location
)
fn before_statement_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_statement: &Statement<'tcx>,
_location: Location
)
See Analysis::apply_before_statement_effect
.
sourcefn before_terminator_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_terminator: &Terminator<'tcx>,
_location: Location
)
fn before_terminator_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_terminator: &Terminator<'tcx>,
_location: Location
)
See Analysis::apply_before_terminator_effect
.
sourcefn yield_resume_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_resume_block: BasicBlock,
_resume_place: Place<'tcx>
)
fn yield_resume_effect(
&self,
_trans: &mut impl GenKill<Self::Idx>,
_resume_block: BasicBlock,
_resume_place: Place<'tcx>
)
See Analysis::apply_yield_resume_effect
.
sourceimpl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, 'tcx>
impl<'a, 'tcx> HasMoveData<'tcx> for MaybeUninitializedPlaces<'a, 'tcx>
Auto Trait Implementations
impl<'a, 'tcx> !RefUnwindSafe for MaybeUninitializedPlaces<'a, 'tcx>
impl<'a, 'tcx> !Send for MaybeUninitializedPlaces<'a, 'tcx>
impl<'a, 'tcx> !Sync for MaybeUninitializedPlaces<'a, 'tcx>
impl<'a, 'tcx> Unpin for MaybeUninitializedPlaces<'a, 'tcx> where
'tcx: 'a,
impl<'a, 'tcx> !UnwindSafe for MaybeUninitializedPlaces<'a, 'tcx>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<'tcx, A, D> RustcPeekAt<'tcx> for A where
A: Analysis<'tcx, Domain = D> + HasMoveData<'tcx>,
D: JoinSemiLattice + Clone + BitSetExt<MovePathIndex>,
impl<'tcx, A, D> RustcPeekAt<'tcx> for A where
A: Analysis<'tcx, Domain = D> + HasMoveData<'tcx>,
D: JoinSemiLattice + Clone + BitSetExt<MovePathIndex>,
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