Enum rustc_codegen_ssa::mir::operand::OperandValue

pub enum OperandValue<V> {
    Ref(PlaceValue<V>),
    Immediate(V),
    Pair(V, V),
    ZeroSized,
}

The representation of a Rust value. The enum variant is in fact uniquely determined by the value’s type, but is kept as a safety check.

Variants

Ref(PlaceValue<V>)

A reference to the actual operand. The data is guaranteed to be valid for the operand’s lifetime. The second value, if any, is the extra data (vtable or length) which indicates that it refers to an unsized rvalue.

An OperandValue must be this variant for any type for which LayoutTypeMethods::is_backend_ref returns true. (That basically amounts to “isn’t one of the other variants”.)

This holds a PlaceValue (like a PlaceRef does) with a pointer to the location holding the value. The type behind that pointer is the one returned by LayoutTypeMethods::backend_type.

Immediate(V)

A single LLVM immediate value.

An OperandValue must be this variant for any type for which LayoutTypeMethods::is_backend_immediate returns true. The backend value in this variant must be the immediate backend type, as returned by LayoutTypeMethods::immediate_backend_type.

Pair(V, V)

A pair of immediate LLVM values. Used by fat pointers too.

An OperandValue must be this variant for any type for which LayoutTypeMethods::is_backend_scalar_pair returns true. The backend values in this variant must be the immediate backend types, as returned by LayoutTypeMethods::scalar_pair_element_backend_type with immediate: true.

ZeroSized

A value taking no bytes, and which therefore needs no LLVM value at all.

If you ever need a V to pass to something, get a fresh poison value from ConstMethods::const_poison.

An OperandValue must be this variant for any type for which is_zst on its Layout returns true. Note however that these values can still require alignment.

Implementations

impl<V: CodegenObject> OperandValue<V>

pub fn immediates_or_place(self) -> Either<ArrayVec<V, 2>, PlaceValue<V>>

If this is ZeroSized/Immediate/Pair, return an array of the 0/1/2 values. If this is Ref, return the place.

pub fn from_immediates(immediates: ArrayVec<V, 2>) -> Self

Given an array of 0/1/2 immediate values, return ZeroSized/Immediate/Pair.

pub fn pointer_parts(self) -> (V, Option<V>)

Treat this value as a pointer and return the data pointer and optional metadata as backend values.

If you’re making a place, use Self::deref instead.

pub fn deref(self, align: Align) -> PlaceValue<V>

Treat this value as a pointer and return the place to which it points.

The pointer immediate doesn’t inherently know its alignment, so you need to pass it in. If you want to get it from a type’s ABI alignment, then maybe you want OperandRef::deref instead.

This is the inverse of PlaceValue::address.

pub(crate) fn is_expected_variant_for_type<'tcx, Cx: LayoutTypeMethods<'tcx>>( &self, cx: &Cx, ty: TyAndLayout<'tcx>, ) -> bool

impl<'a, 'tcx, V: CodegenObject> OperandValue<V>

pub fn poison<Bx: BuilderMethods<'a, 'tcx, Value = V>>( bx: &mut Bx, layout: TyAndLayout<'tcx>, ) -> OperandValue<V>

Returns an OperandValue that’s generally UB to use in any way.

Depending on the layout, returns ZeroSized for ZSTs, an Immediate or Pair containing poison value(s), or a Ref containing a poison pointer.

Supports sized types only.

pub fn store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( self, bx: &mut Bx, dest: PlaceRef<'tcx, V>, )

pub fn volatile_store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( self, bx: &mut Bx, dest: PlaceRef<'tcx, V>, )

pub fn unaligned_volatile_store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( self, bx: &mut Bx, dest: PlaceRef<'tcx, V>, )

pub fn nontemporal_store<Bx: BuilderMethods<'a, 'tcx, Value = V>>( self, bx: &mut Bx, dest: PlaceRef<'tcx, V>, )

pub(crate) fn store_with_flags<Bx: BuilderMethods<'a, 'tcx, Value = V>>( self, bx: &mut Bx, dest: PlaceRef<'tcx, V>, flags: MemFlags, )

pub fn store_unsized<Bx: BuilderMethods<'a, 'tcx, Value = V>>( self, bx: &mut Bx, indirect_dest: PlaceRef<'tcx, V>, )

Trait Implementations

impl<V: Clone> Clone for OperandValue<V>

fn clone(&self) -> OperandValue<V>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<V: Debug> Debug for OperandValue<V>

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

Formats the value using the given formatter.

impl<V: Copy> Copy for OperandValue<V>

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.