Analysis and evaluation of address arithmetic capabilities in custom DSP architectures

Many application-specific architectures provideindirect addressing modes with auto-increment/decrementarithmetic.Since these architectures generally do not featurean indexed addressing mode, stack-allocated variablesmust be accessed by allocating address registers and performingaddress arithmetic.Subsuming address arithmeticinto auto-increment/decrement arithmetic improves boththe performance and size of the generated code.Our objective in this paper is to provide a method forcomprehensively analyzing the performance benefits andhardware cost due to an auto-increment/decrement featurethat varies from -l to +l, and allowing access to k addressregisters in an address generator.We provide this methodvia a parameterizable optimization algorithm that operateson a procedure-wise basis.Hence, the optimizationtechniques in a compiler can be used not only to generateefficient or compact code, but also to help the designerof a custom DSP architecture make decisions on addressarithmetic featuers.We present two sets of experimental results based onselected benchmark programs: (1) the values of l and kbeyond which there is little or no improvement in performance,and (2) the values of l and k which result in minimumcode area.