// This kind of conversion needs a runtime call. Allocate
		// a descriptor for that call.
		n.Descriptor = makeTypeAssertDescriptor(n.Type(), n.Op() == ir.ODOTTYPE2)
	}
	return n
}

func makeTypeAssertDescriptor(target *types.Type, canFail bool) *obj.LSym {
	// When converting from an interface to a non-empty interface. Needs a runtime call.

		// Fixed (not loaded from a dictionary) type.
		ta := ir.NewTypeAssertExpr(base.Pos, c, toType)
		ta.SetOp(ir.ODOTTYPE2)
		// Allocate a descriptor for this conversion to pass to the runtime.
		ta.Descriptor = makeTypeAssertDescriptor(toType, true)
		rhs = ta
	} else {
		ta := ir.NewDynamicTypeAssertExpr(base.Pos, ir.ODYNAMICDOTTYPE2, c, n.TypeWord)
		rhs = ta
	}
	rhs.SetType(toType)
	rhs.SetTypecheck(1)