Decoupling integer execution in superscalar processors

We propose that processor hardware can be used more effectively if floating-point units are augmented to perform simple integer operations. Existing floating-point registers and datapaths are used to support these integer operations. Some integer instructions, those not used for computing addresses and accessing memory, can then be off-loaded to the floating-point units. Consequently, these integer instructions are decoupled from memory accessing, and additional instruction bandwidth is available for integer programs. This paper reports the results of a preliminary study of integer benchmark programs compiled for the SPARC architecture. The results indicate that between 10% and 39% of the instructions in the integer benchmarks can be executed in the augmented floating-point units. Furthermore, these instructions are all simple add, subtract and logical instructions