[_chris_]

> their clean orthogonal instruction encoding is so inefficient (e.g. it wastes a lot of instruction cache)

Perhaps, although ARMv8 is fixed 4 bytes and x86-64 averages more than 4 bytes an instruction despite each x86 instruction mapping to more than 1.0 uops on average. Oops.

[rcxdude]

That doesn't really say anything about efficiency of coding, because you're missing the important component of how much work each instruction represents. If ARMv8 turns 'load, multiply, store' into 3 instructions of 4 bytes and x86 represents that as 1 5-byte instruction decoding to 1 uop, x86 is going to be winning on most counts (2x in terms of code density). Of course the reality is probably going to be closer than this, but your statements contain none of the information to actually make any determination one way or the other.