A dynamic code placement technique for scratchpad memory using postpass optimization

In this paper, we propose a fully automatic dynamic scratch-pad memory (SPM) management technique for instructions. Our technique loads required code segments into the SPM on demand at runtime. Our approach is based on postpass analysis and optimization techniques, and it handles the whole program, including libraries. The code mapping is de-termined by solving mixed integer linear programming for-mulation that approximates our demand paging technique. We increase the effectiveness of demand paging by extract-ing from functions natural loops that are smaller in size and have a higher instruction fetch count. The postpass opti-mizer analyzes the object files of an application and trans-forms them into an application binary image that enables demand paging to the SPM. We evaluate our technique on eleven embedded applications and compare it to a processor core with an instruction cache in terms of its performance and energy consumption. The cache size is about 20 % of the executed code size, and the SPM size is chosen such that its die area is equal to that of the cache. The experi-mental results show that, on average, the processor core and memory subsystem’s energy consumption can be reduced by 21.6 % and the performance improved by 20.2%. Moreover, in comparison with the optimal static placement strategy, our technique reduces energy consumption by 23.7 % and improves performance by 22.9%, on average