Some time ago I had a performance problem that wasn’t easy to explain by just looking at the code, since the version I expected to be faster was actually slower. Since the problem is simple yet illustrative, I am using it as a showcase on how to debug performance issues using llvm-mca.According to it’s documentation llvm-mca is a performance analysis tool that uses information available in LLVM (e.g. scheduling models) to statically measure the performance of machine code in a specific CPU. In o...