Function Inlining in Embedded Systems with Code Size Limitation

Abstract

Function inlining is a widely known technique that has been adopted in compiler optimization research domain. Inlining functions can eliminate the overhead resulted from function calls, but with inlining, the code size also grows unpredictably; this is not suitable for embedded processors whose memory size is relatively small. In this paper, we introduce a novel function inlining approach using the heuristic rebate_ratio, functions to be inlined are selected according to their rebate_ratios in a descending way. This kind of code optimization operation works at the source code level. Comparing with other algorithms, it is easier to implement. Our target is to get an optimal result of function inlining which can achieve the maximum performance improvement while keeping the code size within a defined limit.