1. A method for combining instructions, performed by a compiler, the method comprising: obtaining a plurality of first instructions, wherein each first instruction performs one of a calculation operation, a comparison operation, a logic operation, a selection operation, a branching operation, a LD/ST (Load/Store) operation, a SMP (sampling) operation and a complicated mathematics operation; combining the first instructions as one combined instruction according to data dependencies between the first instructions; and sending the combined instruction to a SP (Stream Processor).