Eliminating Redundant Function Calls

Multiple calls to the same function using the same argument values are often redundant, and the result of the earlier call can be reused. This is similar to the reuse of redundant arithmetic expressions in redundancy elimination. However, only calls that will return the same results and not produce side effects can be reused. In this paper we present a static analysis that determines whether calls to a function can be reused. The results from this analysis are then used to create annotations that the GCC compiler can use to optimize the redundant calls. Using our analysis and compiling with GCC significantly speeds up microbenchmarks, and in many cases allows code to be written in a cleaner style without lost of performance.