Optimizing the memory bandwidth with loop fusion

The memory bandwidth largely determines the performance and energy cost of embedded systems. At the compiler level, several techniques improve the memory bandwidth at the scope of a basic block, but often fail to exploit all. We propose a technique to optimize the memory bandwidth across the boundaries of a basic block. Our technique incrementally fuses loops to better use the available bandwidth. The resulting performance depends on how the data is assigned to the memories of the memory layer. At the same time, the assignment also strongly influences the energy cost. Therefore, we combine in our approach the fusion and assignment decisions. Designers can use our output to trade-off the energy cost with the system's performance.