<FONT face=Verdana>This paper describes a new automatic instruction-se textension approach with bitwise operaton analysis and trans- formations.It introduces a new intermediate bit-manipulation operation to directly describe bitwise accesses.It performs bit-level analysis and optimization

and builds an extended data-flow graph with the new bit-manipulation operations.Experimental results show that extending instruction-set selection based on the new data-flow graph can effectively improve the performance for bitwise computation-intensive applications.