Enum MethodLowering 

pub enum MethodLowering {
    RuntimeSymbol(RuntimeSymbol),
    Intrinsic(&'static str),
    ScalarPrimitive(RuntimeSymbol),
}

How a catalog entry lowers to actual code.

Variants

RuntimeSymbol(RuntimeSymbol)

Lowers to a call into the runtime wrapper named by the ABI manifest, e.g. [RuntimeSymbol::VecPush] (§11.1). Carrying the symbol rather than its name means a catalog row cannot name a wrapper that does not exist, and the row’s allocation/fault behaviour comes from the manifest instead of being restated here.

Intrinsic(&'static str)

Lowers to a compiler intrinsic (no runtime symbol). Reserved for the sequence pipeline and a handful of primitives that the compiler folds directly.

ScalarPrimitive(RuntimeSymbol)

Lowers to a dedicated MIR instruction whose result is a scalar, with this symbol as the out-of-line form the backend’s cold arm calls (ADR-118 decision 6).

The distinction from RuntimeSymbol is not cosmetic and it is not “this one is inlined”. Two facts follow from it that the plain arm cannot express:

• The answer is not a GcRef. The row’s manifest return is AbiRet::RawI64, so the wrapper hands back the scalar channel and the builder decides whether the value is ever boxed at all. Every value answer in the plain arm is an AbiRet::Gc, which is what a_non_faulting_row_with_a_value_result_cannot_answer_the_unit_sentinel checks — and the check is right about that arm, which is why this one is a separate variant rather than a loosening of it.
• The call site’s safepoint status is the instruction’s, not Inst::Call’s. liveness::is_gc_safepoint matches every Inst::Call regardless of the symbol’s Effect, so a Pure primitive lowered as a call spills the whole root set at a point no collection can happen. A row lowered this way gets an instruction MIR can classify honestly.

BitSet.contains is the only row here today. Vec.get/Vec[] want the same treatment and cannot have it yet: their answer is a GcRef element, so they need a Gc-dst instruction rather than a scalar one. See ADR-118’s open questions.

Trait Implementations

impl Clone for MethodLowering

fn clone(&self) -> MethodLowering

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for MethodLowering

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

Formats the value using the given formatter.

impl Eq for MethodLowering

impl PartialEq for MethodLowering

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for MethodLowering