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: Ralf proposes that loading a place not have side-effects. This is what is implemented in miri today. Are these the semantics we want for MIR? Is this something we can even decide without knowing more about Rust’s memory model?
Needs clarifiation: 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
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.
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.
Constant(Box<Constant<'tcx>>)
Constants are already semantically values, and remain unchanged.
Implementations
sourceimpl<'tcx> Operand<'tcx>
impl<'tcx> Operand<'tcx>
sourcepub fn function_handle(
tcx: TyCtxt<'tcx>,
def_id: DefId,
substs: SubstsRef<'tcx>,
span: Span
) -> Self
pub fn function_handle(
tcx: TyCtxt<'tcx>,
def_id: DefId,
substs: SubstsRef<'tcx>,
span: Span
) -> Self
Convenience helper to make a constant that refers to the fn
with given DefId
and substs. Since this is used to synthesize
MIR, assumes user_ty
is None.
pub fn is_move(&self) -> bool
sourcepub fn const_from_scalar(
tcx: TyCtxt<'tcx>,
ty: Ty<'tcx>,
val: Scalar,
span: Span
) -> Operand<'tcx>
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.
pub fn to_copy(&self) -> Self
sourcepub fn place(&self) -> Option<Place<'tcx>>
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.
sourcepub fn constant(&self) -> Option<&Constant<'tcx>>
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.
sourcepub fn const_fn_def(&self) -> Option<(DefId, SubstsRef<'tcx>)>
pub fn const_fn_def(&self) -> Option<(DefId, SubstsRef<'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
sourceimpl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Operand<'tcx>
impl<'tcx, '__ctx> HashStable<StableHashingContext<'__ctx>> for Operand<'tcx>
fn hash_stable(
&self,
__hcx: &mut StableHashingContext<'__ctx>,
__hasher: &mut StableHasher
)
sourceimpl<'tcx> PartialEq<Operand<'tcx>> for Operand<'tcx>
impl<'tcx> PartialEq<Operand<'tcx>> for Operand<'tcx>
sourceimpl<'tcx> TypeFoldable<'tcx> for Operand<'tcx>
impl<'tcx> TypeFoldable<'tcx> for Operand<'tcx>
sourcefn try_fold_with<__F: FallibleTypeFolder<'tcx>>(
self,
__folder: &mut __F
) -> Result<Self, __F::Error>
fn try_fold_with<__F: FallibleTypeFolder<'tcx>>(
self,
__folder: &mut __F
) -> Result<Self, __F::Error>
sourcefn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self
fn fold_with<F: TypeFolder<'tcx>>(self, folder: &mut F) -> Self
try_fold_with
for use with infallible
folders. Do not override this method, to ensure coherence with
try_fold_with
. Read moresourceimpl<'tcx> TypeVisitable<'tcx> for Operand<'tcx>
impl<'tcx> TypeVisitable<'tcx> for Operand<'tcx>
sourcefn visit_with<__V: TypeVisitor<'tcx>>(
&self,
__visitor: &mut __V
) -> ControlFlow<__V::BreakTy>
fn visit_with<__V: TypeVisitor<'tcx>>(
&self,
__visitor: &mut __V
) -> ControlFlow<__V::BreakTy>
sourcefn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool
fn has_vars_bound_at_or_above(&self, binder: DebruijnIndex) -> bool
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. Read moresourcefn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool
fn has_vars_bound_above(&self, binder: DebruijnIndex) -> bool
true
if this self
has any regions that escape binder
(and
hence are not bound by it). Read morefn has_escaping_bound_vars(&self) -> bool
fn has_type_flags(&self, flags: TypeFlags) -> bool
fn has_projections(&self) -> bool
fn has_opaque_types(&self) -> bool
fn references_error(&self) -> bool
fn error_reported(&self) -> Option<ErrorGuaranteed>
fn has_param_types_or_consts(&self) -> bool
fn has_infer_regions(&self) -> bool
fn has_infer_types(&self) -> bool
fn has_infer_types_or_consts(&self) -> bool
fn needs_infer(&self) -> bool
fn has_placeholders(&self) -> bool
fn needs_subst(&self) -> bool
sourcefn has_free_regions(&self) -> bool
fn has_free_regions(&self) -> bool
fn has_erased_regions(&self) -> bool
sourcefn has_erasable_regions(&self) -> bool
fn has_erasable_regions(&self) -> bool
sourcefn is_global(&self) -> bool
fn is_global(&self) -> bool
sourcefn has_late_bound_regions(&self) -> bool
fn has_late_bound_regions(&self) -> bool
sourcefn still_further_specializable(&self) -> bool
fn still_further_specializable(&self) -> bool
impl
specialization. Read moreimpl<'tcx> StructuralPartialEq for Operand<'tcx>
Auto Trait Implementations
impl<'tcx> !RefUnwindSafe for Operand<'tcx>
impl<'tcx> !Send for Operand<'tcx>
impl<'tcx> !Sync for Operand<'tcx>
impl<'tcx> Unpin for Operand<'tcx>
impl<'tcx> !UnwindSafe for Operand<'tcx>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
sourceimpl<Ctxt, T> DepNodeParams<Ctxt> for Twhere
Ctxt: DepContext,
T: for<'a> HashStable<StableHashingContext<'a>> + Debug,
impl<Ctxt, T> DepNodeParams<Ctxt> for Twhere
Ctxt: DepContext,
T: for<'a> HashStable<StableHashingContext<'a>> + Debug,
default fn fingerprint_style() -> FingerprintStyle
sourcedefault fn to_fingerprint(&self, tcx: Ctxt) -> Fingerprint
default fn to_fingerprint(&self, tcx: Ctxt) -> Fingerprint
default fn to_debug_str(&self, Ctxt) -> String
sourcedefault fn recover(Ctxt, &DepNode<<Ctxt as DepContext>::DepKind>) -> Option<T>
default fn recover(Ctxt, &DepNode<<Ctxt as DepContext>::DepKind>) -> Option<T>
DepNode
,
something which is needed when forcing DepNode
s 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. Read moresourceimpl<T, R> InternIteratorElement<T, R> for T
impl<T, R> InternIteratorElement<T, R> for T
type Output = R
fn intern_with<I, F>(iter: I, f: F) -> <T as InternIteratorElement<T, R>>::Outputwhere
I: Iterator<Item = T>,
F: FnOnce(&[T]) -> R,
sourceimpl<T> MaybeResult<T> for T
impl<T> MaybeResult<T> for T
sourceimpl<CTX, T> Value<CTX> for Twhere
CTX: DepContext,
impl<CTX, T> Value<CTX> for Twhere
CTX: DepContext,
default fn from_cycle_error(tcx: CTX) -> T
impl<'a, T> Captures<'a> for Twhere
T: ?Sized,
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 bytesMove
: 16 bytesConstant
: 8 bytes