pub enum Operand<'tcx> {
    Copy(Place<'tcx>),
    Move(Place<'tcx>),
    Constant(Box<Constant<'tcx>>),
}
Expand description

An operand in MIR represents a “value” in Rust, the definition of which is undecided and part of the memory model. One proposal for a definition of values can be found on UCG.

The most common way to create values is via loading a place. Loading a place is an operation which reads the memory of the place and converts it to a value. This is a fundamentally typed operation. The nature of the value produced depends on the type of the conversion. Furthermore, there may be other effects: if the type has a validity constraint loading the place might be UB if the validity constraint is not met.

Needs clarification: Is loading a place that has its variant index set well-formed? Miri currently implements it, but it seems like this may be something to check against in the validator.

Variants§

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Copy(Place<'tcx>)

Creates a value by loading the given place.

Before drop elaboration, the type of the place must be Copy. After drop elaboration there is no such requirement.

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Move(Place<'tcx>)

Creates a value by performing loading the place, just like the Copy operand.

This may additionally overwrite the place with uninit bytes, depending on how we decide in UCG#188. You should not emit MIR that may attempt a subsequent second load of this place without first re-initializing it.

Needs clarification: The operational impact of Move is unclear. Currently (both in Miri and codegen) it has no effect at all unless it appears in an argument to Call; for Call it allows the argument to be passed to the callee “in-place”, i.e. the callee might just get a reference to this place instead of a full copy. Miri implements this with a combination of aliasing model “protectors” and putting uninit into the place. Ralf proposes that we don’t want these semantics for Move in regular assignments, because loading a place should not have side-effects, and the aliasing model “protectors” are inherently tied to a function call. Are these the semantics we want for MIR? Is this something we can even decide without knowing more about Rust’s memory model?

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Constant(Box<Constant<'tcx>>)

Constants are already semantically values, and remain unchanged.

Implementations§

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impl<'tcx> Operand<'tcx>

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pub fn ty<D>(&self, local_decls: &D, tcx: TyCtxt<'tcx>) -> Ty<'tcx>where D: HasLocalDecls<'tcx> + ?Sized,

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impl<'tcx> Operand<'tcx>

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pub fn function_handle( tcx: TyCtxt<'tcx>, def_id: DefId, args: impl IntoIterator<Item = GenericArg<'tcx>>, span: Span ) -> Self

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.

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pub fn is_move(&self) -> bool

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pub fn const_from_scalar( tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, val: Scalar, span: Span ) -> Operand<'tcx>

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.

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pub fn to_copy(&self) -> Self

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pub fn place(&self) -> Option<Place<'tcx>>

Returns the Place that is the target of this Operand, or None if this Operand is a constant.

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pub fn constant(&self) -> Option<&Constant<'tcx>>

Returns the Constant that is the target of this Operand, or None if this Operand is a place.

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pub fn const_fn_def(&self) -> Option<(DefId, GenericArgsRef<'tcx>)>

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.

Trait Implementations§

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impl<'tcx> Clone for Operand<'tcx>

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fn clone(&self) -> Operand<'tcx>

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<'tcx> Debug for Operand<'tcx>

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fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<'tcx, __D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<__D> for Operand<'tcx>

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fn decode(__decoder: &mut __D) -> Self

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impl<'tcx, __E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<__E> for Operand<'tcx>

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fn encode(&self, __encoder: &mut __E)

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impl<'tcx> Hash for Operand<'tcx>

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fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Operand<'tcx>

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fn hash_stable( &self, __hcx: &mut StableHashingContext<'__ctx>, __hasher: &mut StableHasher )

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impl<'tcx> PartialEq<Operand<'tcx>> for Operand<'tcx>

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fn eq(&self, other: &Operand<'tcx>) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Operand<'tcx>

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fn try_fold_with<__F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, __folder: &mut __F ) -> Result<Self, __F::Error>

The entry point for folding. To fold a value t with a folder f call: t.try_fold_with(f). Read more
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fn fold_with<F>(self, folder: &mut F) -> Selfwhere F: TypeFolder<I>,

A convenient alternative to try_fold_with for use with infallible folders. Do not override this method, to ensure coherence with try_fold_with.
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impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Operand<'tcx>

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fn visit_with<__V: TypeVisitor<TyCtxt<'tcx>>>( &self, __visitor: &mut __V ) -> ControlFlow<__V::BreakTy>

The entry point for visiting. To visit a value t with a visitor v call: t.visit_with(v). Read more
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impl<'tcx> StructuralPartialEq for Operand<'tcx>

Auto Trait Implementations§

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impl<'tcx> !RefUnwindSafe for Operand<'tcx>

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impl<'tcx> !Send for Operand<'tcx>

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impl<'tcx> !Sync for Operand<'tcx>

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impl<'tcx> Unpin for Operand<'tcx>

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impl<'tcx> !UnwindSafe for Operand<'tcx>

Blanket Implementations§

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impl<T> Aligned for T

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const ALIGN: Alignment = Alignment::of::<Self>()

Alignment of Self.
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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T, R> CollectAndApply<T, R> for T

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fn collect_and_apply<I, F>(iter: I, f: F) -> Rwhere I: Iterator<Item = T>, F: FnOnce(&[T]) -> R,

Equivalent to f(&iter.collect::<Vec<_>>()).

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type Output = R

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impl<Tcx, T> DepNodeParams<Tcx> for Twhere Tcx: DepContext, T: for<'a> HashStable<StableHashingContext<'a>> + Debug,

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default fn fingerprint_style() -> FingerprintStyle

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default fn to_fingerprint(&self, tcx: Tcx) -> Fingerprint

This method turns the parameters of a DepNodeConstructor into an opaque Fingerprint to be used in DepNode. Not all DepNodeParams support being turned into a Fingerprint (they don’t need to if the corresponding DepNode is anonymous).
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default fn to_debug_str(&self, _: Tcx) -> String

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default fn recover( _: Tcx, _: &DepNode<<Tcx as DepContext>::DepKind> ) -> Option<T>

This method tries to recover the query key from the given DepNode, something which is needed when forcing DepNodes during red-green evaluation. The query system will only call this method if fingerprint_style() is not FingerprintStyle::Opaque. It is always valid to return None here, in which case incremental compilation will treat the query as having changed instead of forcing it.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<P> IntoQueryParam<P> for P

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impl<'tcx, T> IsSuggestable<'tcx> for Twhere T: TypeVisitable<TyCtxt<'tcx>> + TypeFoldable<TyCtxt<'tcx>>,

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fn is_suggestable(self, tcx: TyCtxt<'tcx>, infer_suggestable: bool) -> bool

Whether this makes sense to suggest in a diagnostic. Read more
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fn make_suggestable( self, tcx: TyCtxt<'tcx>, infer_suggestable: bool ) -> Option<T>

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impl<T> MaybeResult<T> for T

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type Error = !

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fn from(_: Result<T, <T as MaybeResult<T>>::Error>) -> T

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fn to_result(self) -> Result<T, <T as MaybeResult<T>>::Error>

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impl<T> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<'tcx, T> ToPredicate<'tcx, T> for T

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fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T

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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<'tcx, T> TypeVisitableExt<'tcx> for Twhere T: TypeVisitable<TyCtxt<'tcx>>,

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fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool

Returns true if self has any late-bound regions that are either bound by binder or bound by some binder outside of binder. If binder is ty::INNERMOST, this indicates whether there are any late-bound regions that appear free.
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fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool

Returns true if this type has any regions that escape binder (and hence are not bound by it).
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fn has_escaping_bound_vars(&self) -> bool

Return true if this type has regions that are not a part of the type. For example, for<'a> fn(&'a i32) return false, while fn(&'a i32) would return true. The latter can occur when traversing through the former. Read more
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fn has_type_flags(&self, flags: TypeFlags) -> bool

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fn has_projections(&self) -> bool

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fn has_inherent_projections(&self) -> bool

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fn has_opaque_types(&self) -> bool

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fn has_generators(&self) -> bool

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fn references_error(&self) -> bool

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fn error_reported(&self) -> Result<(), ErrorGuaranteed>

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fn has_non_region_param(&self) -> bool

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fn has_infer_regions(&self) -> bool

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fn has_infer_types(&self) -> bool

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fn has_non_region_infer(&self) -> bool

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fn has_infer(&self) -> bool

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fn has_placeholders(&self) -> bool

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fn has_non_region_placeholders(&self) -> bool

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fn has_param(&self) -> bool

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fn has_free_regions(&self) -> bool

“Free” regions in this context means that it has any region that is not (a) erased or (b) late-bound.
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fn has_erased_regions(&self) -> bool

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fn has_erasable_regions(&self) -> bool

True if there are any un-erased free regions.
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fn is_global(&self) -> bool

Indicates whether this value references only ‘global’ generic parameters that are the same regardless of what fn we are in. This is used for caching.
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fn has_late_bound_regions(&self) -> bool

True if there are any late-bound regions
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fn has_non_region_late_bound(&self) -> bool

True if there are any late-bound non-region variables
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fn has_late_bound_vars(&self) -> bool

True if there are any late-bound variables
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fn still_further_specializable(&self) -> bool

Indicates whether this value still has parameters/placeholders/inference variables which could be replaced later, in a way that would change the results of impl specialization.
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impl<Tcx, T, D> Value<Tcx, D> for Twhere Tcx: DepContext, D: DepKind,

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default fn from_cycle_error(tcx: Tcx, cycle: &[QueryInfo<D>]) -> T

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:24 bytes

Size for each variant:

  • Copy: 16 bytes
  • Move: 16 bytes
  • Constant: 8 bytes