Implementations of the present specification are provided for interpreting a bytecode instruction stream. An interpreter of a virtual machine receives an instruction stream comprising a plurality of machine instructions. A first value, comprising a current analog function address and stored in a first register corresponding to a current instruction of the plurality of machine instructions, is read. The validity of the first value is determined. If the first value is valid, the first value is stored in a second register configured to store current analog function addresses corresponding to current instructions in the instruction stream. A subsequent analog function address corresponding to a subsequent instruction associated with the current instruction is retrieved by using the current analog function address. The subsequent analog function address is stored in the first register. The current instruction is executed based on the current analog function address read from the second register.