Today, I would consider it fair to say that modern-day processor architectures are no longer designed to be programmed by human beings using assembly language. Instead, they are designed to be programmed using optimizing compilers. And, the vendors of those chips work carefully with compiler-designers (and, produce compilers themselves ...) which will produce "optimal" code sequences in particular situations. Assembly language today is confined to extremely edge-case situations such as the /arch subdirectory of the Linux kernel source-tree.