Class LetAnnotation

python/tvm/tirx/script/builder/ir.py:1477–1507

Marker for explicit LetStmt. Created by T.let or T.let[type]. Usage in TVMScript: x: T.let[T.int32] = expr # LetStmt with explicit type x: T.let = expr # LetStmt with auto-typed RHS

class LetAnnotation:
    """Marker for explicit LetStmt. Created by T.let or T.let[type].
    Usage in TVMScript:
        x: T.let[T.int32] = expr   # LetStmt with explicit type
        x: T.let = expr             # LetStmt with auto-typed RHS
    """

    def __init__(self, type_spec=None):
        self.type_spec = type_spec

    def __class_getitem__(cls, item):
        return LetAnnotation(item)

    def __getitem__(self, item):
        return LetAnnotation(item)

    def as_var(self, rhs_dtype=None):
        """Resolve to a tir.Var."""
        if self.type_spec is not None:
            if isinstance(self.type_spec, Var):
                return self.type_spec  # Already a Var (e.g. T.handle(...))
            elif callable(self.type_spec):
                return self.type_spec()  # e.g. T.int32() -> Var
            elif isinstance(self.type_spec, Type):
                return Var("", self.type_spec)
            else:
                raise TypeError(f"Invalid type for T.let: {self.type_spec}")
        elif rhs_dtype is not None:
            return Var("", ir.PrimType(rhs_dtype))
        else:
            raise TypeError("T.let requires either a type or an RHS value")


let = LetAnnotation()  # Singleton for T.let (no subscript)