Enum RegAllocError 

#[non_exhaustive]
pub enum RegAllocError {
    Mir(MirError),
    PhysLiveIn {
        block: Block,
        reg: PReg,
    },
    PhysClobbered {
        block: Block,
        reg: PReg,
    },
    TooLarge,
    NoRegister {
        class: RegClass,
    },
}

Why a function could not be allocated.

Examples

use backend_lang::mir::{Function, Operand};
use backend_lang::regalloc::{self, RegAllocError};
use backend_lang::x86_64::{op, GPR, SYSV};

let mut f = Function::new("f", &SYSV);
let b = f.block()?;
let v = f.vreg(GPR)?;
let w = f.vreg(GPR)?;
f.push(b, op::MOV64, &[w.into(), v.into()])?; // v is never defined
f.push(b, op::RET, &[])?;
assert!(matches!(regalloc::allocate(&mut f), Err(RegAllocError::Mir(_))));

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Mir(MirError)

The function is malformed or not in SSA form (Function::verify_ssa).

PhysLiveIn

A physical register is live into a block other than through the entry block’s parameters. Physical registers must be block-local: copy values out of them into virtual registers.

Fields

block: Block

The block.

reg: PReg

The register.

PhysClobbered

An instruction writes a physical register that holds a live value (two fixed-register ranges overlap).

Fields

block: Block

The block.

reg: PReg

The register.

TooLarge

The live sets exceed the budget.

NoRegister

No register of the class can hold a value even after spilling everything spillable (the class has no allocatable registers, or a single instruction needs more than the class has).

Fields

class: RegClass

The class.

Trait Implementations

impl Clone for RegAllocError

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for RegAllocError

impl Debug for RegAllocError

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

Formats the value using the given formatter.

impl Display for RegAllocError

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

Formats the value using the given formatter.

impl Eq for RegAllocError

impl Error for RegAllocError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

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

Provides type-based access to context intended for error reports.

impl From<MirError> for RegAllocError

fn from(e: MirError) -> RegAllocError

Converts to this type from the input type.

impl Hash for RegAllocError

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 PartialEq for RegAllocError

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for RegAllocError