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/// Functionality for statements, operands, places, and things that appear in them.
use super::{interpret::GlobalAlloc, *};
///////////////////////////////////////////////////////////////////////////
// Statements
/// A statement in a basic block, including information about its source code.
#[derive(Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub struct Statement<'tcx> {
pub source_info: SourceInfo,
pub kind: StatementKind<'tcx>,
}
impl Statement<'_> {
/// Changes a statement to a nop. This is both faster than deleting instructions and avoids
/// invalidating statement indices in `Location`s.
pub fn make_nop(&mut self) {
self.kind = StatementKind::Nop
}
/// Changes a statement to a nop and returns the original statement.
#[must_use = "If you don't need the statement, use `make_nop` instead"]
pub fn replace_nop(&mut self) -> Self {
Statement {
source_info: self.source_info,
kind: mem::replace(&mut self.kind, StatementKind::Nop),
}
}
}
impl<'tcx> StatementKind<'tcx> {
pub fn as_assign_mut(&mut self) -> Option<&mut (Place<'tcx>, Rvalue<'tcx>)> {
match self {
StatementKind::Assign(x) => Some(x),
_ => None,
}
}
pub fn as_assign(&self) -> Option<&(Place<'tcx>, Rvalue<'tcx>)> {
match self {
StatementKind::Assign(x) => Some(x),
_ => None,
}
}
}
///////////////////////////////////////////////////////////////////////////
// Places
impl<V, T> ProjectionElem<V, T> {
/// Returns `true` if the target of this projection may refer to a different region of memory
/// than the base.
fn is_indirect(&self) -> bool {
match self {
Self::Deref => true,
Self::Field(_, _)
| Self::Index(_)
| Self::OpaqueCast(_)
| Self::Subtype(_)
| Self::ConstantIndex { .. }
| Self::Subslice { .. }
| Self::Downcast(_, _) => false,
}
}
/// Returns `true` if the target of this projection always refers to the same memory region
/// whatever the state of the program.
pub fn is_stable_offset(&self) -> bool {
match self {
Self::Deref | Self::Index(_) => false,
Self::Field(_, _)
| Self::OpaqueCast(_)
| Self::Subtype(_)
| Self::ConstantIndex { .. }
| Self::Subslice { .. }
| Self::Downcast(_, _) => true,
}
}
/// Returns `true` if this is a `Downcast` projection with the given `VariantIdx`.
pub fn is_downcast_to(&self, v: VariantIdx) -> bool {
matches!(*self, Self::Downcast(_, x) if x == v)
}
/// Returns `true` if this is a `Field` projection with the given index.
pub fn is_field_to(&self, f: FieldIdx) -> bool {
matches!(*self, Self::Field(x, _) if x == f)
}
/// Returns `true` if this is accepted inside `VarDebugInfoContents::Place`.
pub fn can_use_in_debuginfo(&self) -> bool {
match self {
Self::ConstantIndex { from_end: false, .. }
| Self::Deref
| Self::Downcast(_, _)
| Self::Field(_, _) => true,
Self::ConstantIndex { from_end: true, .. }
| Self::Index(_)
| Self::Subtype(_)
| Self::OpaqueCast(_)
| Self::Subslice { .. } => false,
}
}
}
/// Alias for projections as they appear in `UserTypeProjection`, where we
/// need neither the `V` parameter for `Index` nor the `T` for `Field`.
pub type ProjectionKind = ProjectionElem<(), ()>;
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct PlaceRef<'tcx> {
pub local: Local,
pub projection: &'tcx [PlaceElem<'tcx>],
}
// Once we stop implementing `Ord` for `DefId`,
// this impl will be unnecessary. Until then, we'll
// leave this impl in place to prevent re-adding a
// dependency on the `Ord` impl for `DefId`
impl<'tcx> !PartialOrd for PlaceRef<'tcx> {}
impl<'tcx> Place<'tcx> {
// FIXME change this to a const fn by also making List::empty a const fn.
pub fn return_place() -> Place<'tcx> {
Place { local: RETURN_PLACE, projection: List::empty() }
}
/// Returns `true` if this `Place` contains a `Deref` projection.
///
/// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the
/// same region of memory as its base.
pub fn is_indirect(&self) -> bool {
self.projection.iter().any(|elem| elem.is_indirect())
}
/// Returns `true` if this `Place`'s first projection is `Deref`.
///
/// This is useful because for MIR phases `AnalysisPhase::PostCleanup` and later,
/// `Deref` projections can only occur as the first projection. In that case this method
/// is equivalent to `is_indirect`, but faster.
pub fn is_indirect_first_projection(&self) -> bool {
self.as_ref().is_indirect_first_projection()
}
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
/// a single deref of a local.
#[inline(always)]
pub fn local_or_deref_local(&self) -> Option<Local> {
self.as_ref().local_or_deref_local()
}
/// If this place represents a local variable like `_X` with no
/// projections, return `Some(_X)`.
#[inline(always)]
pub fn as_local(&self) -> Option<Local> {
self.as_ref().as_local()
}
#[inline]
pub fn as_ref(&self) -> PlaceRef<'tcx> {
PlaceRef { local: self.local, projection: &self.projection }
}
/// Iterate over the projections in evaluation order, i.e., the first element is the base with
/// its projection and then subsequently more projections are added.
/// As a concrete example, given the place a.b.c, this would yield:
/// - (a, .b)
/// - (a.b, .c)
///
/// Given a place without projections, the iterator is empty.
#[inline]
pub fn iter_projections(
self,
) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
self.as_ref().iter_projections()
}
/// Generates a new place by appending `more_projections` to the existing ones
/// and interning the result.
pub fn project_deeper(self, more_projections: &[PlaceElem<'tcx>], tcx: TyCtxt<'tcx>) -> Self {
if more_projections.is_empty() {
return self;
}
self.as_ref().project_deeper(more_projections, tcx)
}
}
impl From<Local> for Place<'_> {
#[inline]
fn from(local: Local) -> Self {
Place { local, projection: List::empty() }
}
}
impl<'tcx> PlaceRef<'tcx> {
/// Finds the innermost `Local` from this `Place`, *if* it is either a local itself or
/// a single deref of a local.
pub fn local_or_deref_local(&self) -> Option<Local> {
match *self {
PlaceRef { local, projection: [] }
| PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local),
_ => None,
}
}
/// Returns `true` if this `Place` contains a `Deref` projection.
///
/// If `Place::is_indirect` returns false, the caller knows that the `Place` refers to the
/// same region of memory as its base.
pub fn is_indirect(&self) -> bool {
self.projection.iter().any(|elem| elem.is_indirect())
}
/// Returns `true` if this `Place`'s first projection is `Deref`.
///
/// This is useful because for MIR phases `AnalysisPhase::PostCleanup` and later,
/// `Deref` projections can only occur as the first projection. In that case this method
/// is equivalent to `is_indirect`, but faster.
pub fn is_indirect_first_projection(&self) -> bool {
// To make sure this is not accidentally used in wrong mir phase
debug_assert!(
self.projection.is_empty() || !self.projection[1..].contains(&PlaceElem::Deref)
);
self.projection.first() == Some(&PlaceElem::Deref)
}
/// If this place represents a local variable like `_X` with no
/// projections, return `Some(_X)`.
#[inline]
pub fn as_local(&self) -> Option<Local> {
match *self {
PlaceRef { local, projection: [] } => Some(local),
_ => None,
}
}
#[inline]
pub fn last_projection(&self) -> Option<(PlaceRef<'tcx>, PlaceElem<'tcx>)> {
if let &[ref proj_base @ .., elem] = self.projection {
Some((PlaceRef { local: self.local, projection: proj_base }, elem))
} else {
None
}
}
/// Iterate over the projections in evaluation order, i.e., the first element is the base with
/// its projection and then subsequently more projections are added.
/// As a concrete example, given the place a.b.c, this would yield:
/// - (a, .b)
/// - (a.b, .c)
///
/// Given a place without projections, the iterator is empty.
#[inline]
pub fn iter_projections(
self,
) -> impl Iterator<Item = (PlaceRef<'tcx>, PlaceElem<'tcx>)> + DoubleEndedIterator {
self.projection.iter().enumerate().map(move |(i, proj)| {
let base = PlaceRef { local: self.local, projection: &self.projection[..i] };
(base, *proj)
})
}
/// Generates a new place by appending `more_projections` to the existing ones
/// and interning the result.
pub fn project_deeper(
self,
more_projections: &[PlaceElem<'tcx>],
tcx: TyCtxt<'tcx>,
) -> Place<'tcx> {
let mut v: Vec<PlaceElem<'tcx>>;
let new_projections = if self.projection.is_empty() {
more_projections
} else {
v = Vec::with_capacity(self.projection.len() + more_projections.len());
v.extend(self.projection);
v.extend(more_projections);
&v
};
Place { local: self.local, projection: tcx.mk_place_elems(new_projections) }
}
}
impl From<Local> for PlaceRef<'_> {
#[inline]
fn from(local: Local) -> Self {
PlaceRef { local, projection: &[] }
}
}
///////////////////////////////////////////////////////////////////////////
// Operands
impl<'tcx> Operand<'tcx> {
/// Convenience helper to make a constant that refers to the fn
/// with given `DefId` and args. Since this is used to synthesize
/// MIR, assumes `user_ty` is None.
pub fn function_handle(
tcx: TyCtxt<'tcx>,
def_id: DefId,
args: impl IntoIterator<Item = GenericArg<'tcx>>,
span: Span,
) -> Self {
let ty = Ty::new_fn_def(tcx, def_id, args);
Operand::Constant(Box::new(ConstOperand {
span,
user_ty: None,
const_: Const::Val(ConstValue::ZeroSized, ty),
}))
}
pub fn is_move(&self) -> bool {
matches!(self, Operand::Move(..))
}
/// Convenience helper to make a literal-like constant from a given scalar value.
/// Since this is used to synthesize MIR, assumes `user_ty` is None.
pub fn const_from_scalar(
tcx: TyCtxt<'tcx>,
ty: Ty<'tcx>,
val: Scalar,
span: Span,
) -> Operand<'tcx> {
debug_assert!({
let param_env_and_ty = ty::ParamEnv::empty().and(ty);
let type_size = tcx
.layout_of(param_env_and_ty)
.unwrap_or_else(|e| panic!("could not compute layout for {ty:?}: {e:?}"))
.size;
let scalar_size = match val {
Scalar::Int(int) => int.size(),
_ => panic!("Invalid scalar type {val:?}"),
};
scalar_size == type_size
});
Operand::Constant(Box::new(ConstOperand {
span,
user_ty: None,
const_: Const::Val(ConstValue::Scalar(val), ty),
}))
}
pub fn to_copy(&self) -> Self {
match *self {
Operand::Copy(_) | Operand::Constant(_) => self.clone(),
Operand::Move(place) => Operand::Copy(place),
}
}
/// Returns the `Place` that is the target of this `Operand`, or `None` if this `Operand` is a
/// constant.
pub fn place(&self) -> Option<Place<'tcx>> {
match self {
Operand::Copy(place) | Operand::Move(place) => Some(*place),
Operand::Constant(_) => None,
}
}
/// Returns the `ConstOperand` that is the target of this `Operand`, or `None` if this `Operand` is a
/// place.
pub fn constant(&self) -> Option<&ConstOperand<'tcx>> {
match self {
Operand::Constant(x) => Some(&**x),
Operand::Copy(_) | Operand::Move(_) => None,
}
}
/// Gets the `ty::FnDef` from an operand if it's a constant function item.
///
/// While this is unlikely in general, it's the normal case of what you'll
/// find as the `func` in a [`TerminatorKind::Call`].
pub fn const_fn_def(&self) -> Option<(DefId, GenericArgsRef<'tcx>)> {
let const_ty = self.constant()?.const_.ty();
if let ty::FnDef(def_id, args) = *const_ty.kind() { Some((def_id, args)) } else { None }
}
}
impl<'tcx> ConstOperand<'tcx> {
pub fn check_static_ptr(&self, tcx: TyCtxt<'_>) -> Option<DefId> {
match self.const_.try_to_scalar() {
Some(Scalar::Ptr(ptr, _size)) => match tcx.global_alloc(ptr.provenance) {
GlobalAlloc::Static(def_id) => {
assert!(!tcx.is_thread_local_static(def_id));
Some(def_id)
}
_ => None,
},
_ => None,
}
}
#[inline]
pub fn ty(&self) -> Ty<'tcx> {
self.const_.ty()
}
}
///////////////////////////////////////////////////////////////////////////
/// Rvalues
impl<'tcx> Rvalue<'tcx> {
/// Returns true if rvalue can be safely removed when the result is unused.
#[inline]
pub fn is_safe_to_remove(&self) -> bool {
match self {
// Pointer to int casts may be side-effects due to exposing the provenance.
// While the model is undecided, we should be conservative. See
// <https://www.ralfj.de/blog/2022/04/11/provenance-exposed.html>
Rvalue::Cast(CastKind::PointerExposeAddress, _, _) => false,
Rvalue::Use(_)
| Rvalue::CopyForDeref(_)
| Rvalue::Repeat(_, _)
| Rvalue::Ref(_, _, _)
| Rvalue::ThreadLocalRef(_)
| Rvalue::AddressOf(_, _)
| Rvalue::Len(_)
| Rvalue::Cast(
CastKind::IntToInt
| CastKind::FloatToInt
| CastKind::FloatToFloat
| CastKind::IntToFloat
| CastKind::FnPtrToPtr
| CastKind::PtrToPtr
| CastKind::PointerCoercion(_)
| CastKind::PointerFromExposedAddress
| CastKind::DynStar
| CastKind::Transmute,
_,
_,
)
| Rvalue::BinaryOp(_, _)
| Rvalue::CheckedBinaryOp(_, _)
| Rvalue::NullaryOp(_, _)
| Rvalue::UnaryOp(_, _)
| Rvalue::Discriminant(_)
| Rvalue::Aggregate(_, _)
| Rvalue::ShallowInitBox(_, _) => true,
}
}
}
impl BorrowKind {
pub fn mutability(&self) -> Mutability {
match *self {
BorrowKind::Shared | BorrowKind::Shallow => Mutability::Not,
BorrowKind::Mut { .. } => Mutability::Mut,
}
}
pub fn allows_two_phase_borrow(&self) -> bool {
match *self {
BorrowKind::Shared
| BorrowKind::Shallow
| BorrowKind::Mut { kind: MutBorrowKind::Default | MutBorrowKind::ClosureCapture } => {
false
}
BorrowKind::Mut { kind: MutBorrowKind::TwoPhaseBorrow } => true,
}
}
}