Can I Beat Clang’s Auto-Vectorizer on Apple Silicon? A SAXPY Case Study
I tried to hand-write NEON intrinsics on Apple Silicon, tune loop unrolling, and beat Clang’s auto-vectorizer. Spoiler: it’s harder than it looks. On modern CPUs, the “slow” part of your code often isn’t the math, it’s how you feed the math units. Compilers try to fix this with clever optimizations, such as auto-vectorization: transforming scalar loops and turn them into SIMD (Single Instruction, Multiple Data) operations that process multiple data points in parallel. ...