Abstract: A system and method for reducing the cycle time necessary to execute semantic routines in a processor that emulates guest instructions. Each of the semantic routines includes a block of host instructions for performing the function of the corresponding guest instruction, and the last instruction in each of the semantic routines is a branch instruction. The method and system first determines the block length of each of the semantic routines. When a first guest instruction is encountered, the block of instructions in a first semantic routine corresponding to a guest instruction is executed. The block length of first semantic routine is then used to determine when to fetch a second semantic routine without fetching and decoding the branch instruction in the first semantic routine, thereby increasing emulation performance.

Abstract: A method and system are disclosed for processing instructions within a data processing system including a processor having a plurality of execution units. According to the method of the present invention, a number of instructions stored within a memory within the data processing system are retrieved from memory. A selected instruction among the number of instructions is decoded to determine if the selected instruction would be noneffective if executed by the processor. In a preferred embodiment of the present invention, noneffective instructions include instructions with invalid opcodes and instructions that would not change the value of any data register within the processor. In response to determining that the selected instruction would be noneffective if executed by the processor, the selected instruction is recoded into a specified instruction format prior to dispatching the selected instruction to one of the number of execution units.