xe := efaceOf(&x)
		xe._type = t
		xe.data = unsafe.Pointer(sl)
	case abi.Pointer:
		et := (*ptrtype)(unsafe.Pointer(t)).Elem
		e2 := newobject(et)
		typedmemmove(et, e2, e.data)
		xe := efaceOf(&x)
		xe._type = t
		xe.data = e2
	}
	return x
}

const (
	// userArenaChunkBytes is the size of a user arena chunk.
	userArenaChunkBytesMax = 8 << 20