Pushing the Limits: Hand-written ARM Cortex-A53 NEON Assembly Kernel

This post delves into optimizing NEON assembly kernels for the ARM Cortex-A53. Using y[n] = ax[n] + b as an example, the author meticulously explains how to leverage the Cortex-A53's instruction timing characteristics (partial dual-issue capabilities and in-order execution) to overcome the limitations of the 64-bit load data path. Techniques like instruction pipelining and prefetching are employed to maximize performance. The hand-written assembly kernel significantly outperforms LLVM-generated code, highlighting the potential of manual optimization when robust CPU models are lacking.