It's not mentioned in the article, so I'll note that the code presented is Windows-specific. Windows uses a different calling convention (https://en.wikipedia.org/wiki/X86_calling_conventions#Micros...) from the one used on Mac and Linux systems (https://en.wikipedia.org/wiki/X86_calling_conventions#System...), so if you want to see the assembly you get from clang on Mac, you'll want to annotate sortRoutine with __attribute__((ms_abi)).