Enum rustc_middle::mir::ConstValue

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pub enum ConstValue<'tcx> {
    Scalar(Scalar),
    ZeroSized,
    Slice {
        data: ConstAllocation<'tcx>,
        meta: u64,
    },
    Indirect {
        alloc_id: AllocId,
        offset: Size,
    },
}
Expand description

Represents a constant value in Rust. Scalar and Slice are optimizations for array length computations, enum discriminants and the pattern matching logic.

Variants§

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Scalar(Scalar)

Used for types with layout::abi::Scalar ABI.

Not using the enum Value to encode that this must not be Uninit.

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ZeroSized

Only for ZSTs.

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Slice

Used for references to unsized types with slice tail.

This is worth an optimized representation since Rust has literals of type &str and &[u8]. Not having to indirect those through an AllocId (or two, if we used Indirect) has shown measurable performance improvements on stress tests. We then reuse this optimization for slice-tail types more generally during valtree-to-constval conversion.

Fields

§data: ConstAllocation<'tcx>

The allocation storing the slice contents. This always points to the beginning of the allocation.

§meta: u64

The metadata field of the reference. This is a “target usize”, so we use u64 as in the interpreter.

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Indirect

A value not representable by the other variants; needs to be stored in-memory.

Must not be used for scalars or ZST, but having &str or other slices in this variant is fine.

Fields

§alloc_id: AllocId

The backing memory of the value. May contain more memory than needed for just the value if this points into some other larger ConstValue.

We use an AllocId here instead of a ConstAllocation<'tcx> to make sure that when a raw constant (which is basically just an AllocId) is turned into a ConstValue and back, we can preserve the original AllocId.

§offset: Size

Offset into alloc

Implementations§

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impl<'tcx> ConstValue<'tcx>

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pub fn try_to_scalar(&self) -> Option<Scalar>

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pub fn try_to_scalar_int(&self) -> Option<ScalarInt>

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pub fn try_to_bits(&self, size: Size) -> Option<u128>

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pub fn try_to_bool(&self) -> Option<bool>

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pub fn try_to_target_usize(&self, tcx: TyCtxt<'tcx>) -> Option<u64>

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pub fn try_to_bits_for_ty( &self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx> ) -> Option<u128>

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pub fn from_bool(b: bool) -> Self

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pub fn from_u64(i: u64) -> Self

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pub fn from_u128(i: u128) -> Self

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pub fn from_target_usize(i: u64, cx: &impl HasDataLayout) -> Self

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pub fn try_get_slice_bytes_for_diagnostics( &self, tcx: TyCtxt<'tcx> ) -> Option<&'tcx [u8]>

Must only be called on constants of type &str or &[u8]!

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pub fn may_have_provenance(&self, tcx: TyCtxt<'tcx>, size: Size) -> bool

Check if a constant may contain provenance information. This is used by MIR opts. Can return true even if there is no provenance.

Trait Implementations§

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impl<'tcx> Clone for ConstValue<'tcx>

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

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fn fmt(&self, f: &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 ConstValue<'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 ConstValue<'tcx>

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

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impl<'tcx> EraseType for ConstValue<'tcx>

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type Result = [u8; 24]

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impl<'tcx> Hash for ConstValue<'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 ConstValue<'tcx>

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

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impl<'tcx, '__lifted> Lift<TyCtxt<'__lifted>> for ConstValue<'tcx>

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type Lifted = ConstValue<'__lifted>

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fn lift_to_tcx(self, __tcx: TyCtxt<'__lifted>) -> Option<ConstValue<'__lifted>>

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impl<'tcx> PartialEq for ConstValue<'tcx>

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fn eq(&self, other: &ConstValue<'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 ConstValue<'tcx>

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fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>( self, _: &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: TypeFolder<TyCtxt<'tcx>>>(self, _: &mut F) -> Self

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 ConstValue<'tcx>

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fn visit_with<F: TypeVisitor<TyCtxt<'tcx>>>(&self, _: &mut F) -> F::Result

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> Copy for ConstValue<'tcx>

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impl<'tcx> Eq for ConstValue<'tcx>

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impl<'tcx> StructuralPartialEq for ConstValue<'tcx>

Auto Trait Implementations§

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impl<'tcx> DynSend for ConstValue<'tcx>

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impl<'tcx> DynSync for ConstValue<'tcx>

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impl<'tcx> Freeze for ConstValue<'tcx>

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impl<'tcx> RefUnwindSafe for ConstValue<'tcx>

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impl<'tcx> Send for ConstValue<'tcx>

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impl<'tcx> Sync for ConstValue<'tcx>

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impl<'tcx> Unpin for ConstValue<'tcx>

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impl<'tcx> UnwindSafe for ConstValue<'tcx>

Blanket Implementations§

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impl<T> Aligned for T

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const ALIGN: Alignment = _

Alignment of Self.
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impl<T> Any for T
where 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> AnyEq for T
where T: Any + PartialEq,

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fn equals(&self, other: &(dyn Any + 'static)) -> bool

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fn as_any(&self) -> &(dyn Any + 'static)

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impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T> ) -> &'a mut [T]

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impl<'tcx, T> ArenaAllocatable<'tcx, IsCopy> for T
where T: Copy,

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fn allocate_on<'a>(self, arena: &'a Arena<'tcx>) -> &'a mut T

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fn allocate_from_iter<'a>( arena: &'a Arena<'tcx>, iter: impl IntoIterator<Item = T> ) -> &'a mut [T]

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impl<T> Borrow<T> for T
where 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 T
where 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) -> R
where 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 T
where 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) -> 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<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<T> Filterable for T

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fn filterable( self, filter_name: &'static str ) -> RequestFilterDataProvider<T, fn(_: DataRequest<'_>) -> bool>

Creates a filterable data provider with the given name for debugging. Read more
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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> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where 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<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<P> IntoQueryParam<P> for P

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impl<'tcx, T> IsSuggestable<'tcx> for T
where 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, placeholder: Option<Ty<'tcx>> ) -> 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> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same for T

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type Output = T

Should always be Self
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impl<T> ToOwned for T
where 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<T, U> TryFrom<U> for T
where 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 T
where 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<I, T> TypeVisitableExt<I> for T
where I: Interner, T: TypeVisitable<I>,

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fn has_type_flags(&self, flags: TypeFlags) -> bool

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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 error_reported(&self) -> Result<(), <I as Interner>::ErrorGuaranteed>

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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_aliases(&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_coroutines(&self) -> bool

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fn references_error(&self) -> bool

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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_bound_regions(&self) -> bool

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

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

True if there are any 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<I, T, U> Upcast<I, U> for T
where U: UpcastFrom<I, T>,

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fn upcast(self, interner: I) -> U

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impl<I, T> UpcastFrom<I, T> for T

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fn upcast_from(from: T, _tcx: I) -> T

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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<Tcx, T> Value<Tcx> for T
where Tcx: DepContext,

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default fn from_cycle_error( tcx: Tcx, cycle_error: &CycleError, _guar: ErrorGuaranteed ) -> T

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<'a, T> Captures<'a> for T
where T: ?Sized,

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impl<T> ErasedDestructor for T
where T: 'static,

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impl<T> MaybeSendSync for T
where T: Send + Sync,

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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:

  • Scalar: 24 bytes
  • ZeroSized: 0 bytes
  • Slice: 24 bytes
  • Indirect: 24 bytes