Enum Constraint 

pub enum Constraint {
    Reg,
    Any,
    Stack,
    Fixed(PhysReg),
    Reuse(u8),
}

Where an operand is allowed to live.

The set is regalloc2’s, which spec/10-backend.md section 10.4 says the allocator interface follows. Constraint::Reg is the default rather than Constraint::Any because a machine instruction wants its operands in registers unless it has said otherwise, and a default that permits a stack slot would turn every rule that forgot to say so into a spill.

Variants

Reg

Any register of its class.

Any

A register or a stack slot, whichever the allocator prefers.

Stack

A stack slot, which is what an operand too large for a register asks for.

Fixed(PhysReg)

That register and no other, which is how a call says where an argument goes and how a division says where its dividend goes.

Reuse(u8)

The same register as the operand at that index, which is what a two-address form on x86-64 needs: the destination is the first source, and the allocator is the one that has to make that true.

Trait Implementations

impl Clone for Constraint

fn clone(&self) -> Constraint

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Constraint

impl Debug for Constraint

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

Formats the value using the given formatter.

impl Eq for Constraint

impl Hash for Constraint

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

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Constraint

fn cmp(&self, other: &Constraint) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Constraint

fn eq(&self, other: &Constraint) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for Constraint

fn partial_cmp(&self, other: &Constraint) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for Constraint