Struct rustc_mir::transform::generator::EnsureGeneratorFieldAssignmentsNeverAlias

struct EnsureGeneratorFieldAssignmentsNeverAlias<'a> {
    saved_locals: &'a GeneratorSavedLocals,
    storage_conflicts: &'a BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal>,
    assigned_local: Option<GeneratorSavedLocal>,
}

Looks for any assignments between locals (e.g., _4 = _5) that will both be converted to fields in the generator state machine but whose storage is not marked as conflicting

Validation needs to happen immediately before TransformVisitor is invoked, not after.

This condition would arise when the assignment is the last use of _5 but the initial definition of _4 if we weren't extra careful to mark all locals used inside a statement as conflicting. Non-conflicting generator saved locals may be stored at the same location within the generator state machine, which would result in ill-formed MIR: the left-hand and right-hand sides of an assignment may not alias. This caused a miscompilation in #73137.

Fields

saved_locals: &'a GeneratorSavedLocals

storage_conflicts: &'a BitMatrix<GeneratorSavedLocal, GeneratorSavedLocal>

assigned_local: Option<GeneratorSavedLocal>

Implementations

impl<'_> EnsureGeneratorFieldAssignmentsNeverAlias<'_>

fn saved_local_for_direct_place(
    &self,
    place: Place<'_>
) -> Option<GeneratorSavedLocal>

fn check_assigned_place<'tcx>(
    &mut self,
    place: Place<'tcx>,
    f: impl FnOnce(&mut Self)
)

Trait Implementations

impl<'tcx, '_> Visitor<'tcx> for EnsureGeneratorFieldAssignmentsNeverAlias<'_>

fn visit_place(
    &mut self,
    place: &Place<'tcx>,
    context: PlaceContext,
    location: Location
)

fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location)

fn visit_terminator(
    &mut self,
    terminator: &Terminator<'tcx>,
    location: Location
)

fn visit_body(&mut self, body: &Body<'tcx>)

fn visit_basic_block_data(
    &mut self,
    block: BasicBlock,
    data: &BasicBlockData<'tcx>
)

fn visit_source_scope_data(&mut self, scope_data: &SourceScopeData<'tcx>)

fn visit_assign(
    &mut self,
    place: &Place<'tcx>,
    rvalue: &Rvalue<'tcx>,
    location: Location
)

fn visit_assert_message(
    &mut self,
    msg: &AssertKind<Operand<'tcx>>,
    location: Location
)

fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location)

fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location)

fn visit_ascribe_user_ty(
    &mut self,
    place: &Place<'tcx>,
    variance: &Variance,
    user_ty: &UserTypeProjection,
    location: Location
)

fn visit_coverage(&mut self, coverage: &Coverage, location: Location)

fn visit_retag(
    &mut self,
    kind: &RetagKind,
    place: &Place<'tcx>,
    location: Location
)

fn visit_projection(
    &mut self,
    local: Local,
    projection: &[ProjectionElem<Local, &'tcx TyS<'tcx>>],
    context: PlaceContext,
    location: Location
)

fn visit_projection_elem(
    &mut self,
    local: Local,
    proj_base: &[ProjectionElem<Local, &'tcx TyS<'tcx>>],
    elem: ProjectionElem<Local, &'tcx TyS<'tcx>>,
    context: PlaceContext,
    location: Location
)

fn super_place(
    &mut self,
    place: &Place<'tcx>,
    context: PlaceContext,
    location: Location
)

fn super_projection(
    &mut self,
    local: Local,
    projection: &[ProjectionElem<Local, &'tcx TyS<'tcx>>],
    context: PlaceContext,
    location: Location
)

fn super_projection_elem(
    &mut self,
    _local: Local,
    _proj_base: &[ProjectionElem<Local, &'tcx TyS<'tcx>>],
    elem: ProjectionElem<Local, &'tcx TyS<'tcx>>,
    _context: PlaceContext,
    location: Location
)

fn visit_constant(&mut self, constant: &Constant<'tcx>, location: Location)

fn visit_span(&mut self, span: &Span)

fn visit_source_info(&mut self, source_info: &SourceInfo)

fn visit_ty(&mut self, ty: &'tcx TyS<'tcx>, TyContext)

fn visit_user_type_projection(&mut self, ty: &UserTypeProjection)

fn visit_user_type_annotation(
    &mut self,
    index: UserTypeAnnotationIndex,
    ty: &CanonicalUserTypeAnnotation<'tcx>
)

fn visit_region(&mut self, region: &&'tcx RegionKind, Location)

fn visit_const(&mut self, constant: &&'tcx Const<'tcx>, Location)

fn visit_substs(&mut self, substs: &&'tcx List<GenericArg<'tcx>>, Location)

fn visit_local_decl(&mut self, local: Local, local_decl: &LocalDecl<'tcx>)

fn visit_var_debug_info(&mut self, var_debug_info: &VarDebugInfo<'tcx>)

fn visit_local(
    &mut self,
    _local: &Local,
    _context: PlaceContext,
    _location: Location
)

fn visit_source_scope(&mut self, scope: &SourceScope)

fn super_body(&mut self, body: &Body<'tcx>)

fn super_basic_block_data(
    &mut self,
    block: BasicBlock,
    data: &BasicBlockData<'tcx>
)

fn super_source_scope_data(&mut self, scope_data: &SourceScopeData<'tcx>)

fn super_statement(&mut self, statement: &Statement<'tcx>, location: Location)

fn super_assign(
    &mut self,
    place: &Place<'tcx>,
    rvalue: &Rvalue<'tcx>,
    location: Location
)

fn super_terminator(
    &mut self,
    terminator: &Terminator<'tcx>,
    location: Location
)

fn super_assert_message(
    &mut self,
    msg: &AssertKind<Operand<'tcx>>,
    location: Location
)

fn super_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location)

fn super_operand(&mut self, operand: &Operand<'tcx>, location: Location)

fn super_ascribe_user_ty(
    &mut self,
    place: &Place<'tcx>,
    _variance: &Variance,
    user_ty: &UserTypeProjection,
    location: Location
)

fn super_coverage(&mut self, _coverage: &Coverage, _location: Location)

fn super_retag(
    &mut self,
    _kind: &RetagKind,
    place: &Place<'tcx>,
    location: Location
)

fn super_local_decl(&mut self, local: Local, local_decl: &LocalDecl<'tcx>)

fn super_var_debug_info(&mut self, var_debug_info: &VarDebugInfo<'tcx>)

fn super_source_scope(&mut self, _scope: &SourceScope)

fn super_constant(&mut self, constant: &Constant<'tcx>, location: Location)

fn super_span(&mut self, _span: &Span)

fn super_source_info(&mut self, source_info: &SourceInfo)

fn super_user_type_projection(&mut self, _ty: &UserTypeProjection)

fn super_user_type_annotation(
    &mut self,
    _index: UserTypeAnnotationIndex,
    ty: &CanonicalUserTypeAnnotation<'tcx>
)

fn super_ty(&mut self, _ty: &'tcx TyS<'tcx>)

fn super_region(&mut self, _region: &&'tcx RegionKind)

fn super_const(&mut self, _const: &&'tcx Const<'tcx>)

fn super_substs(&mut self, _substs: &&'tcx List<GenericArg<'tcx>>)

fn visit_location(&mut self, body: &Body<'tcx>, location: Location)