> That's great and all, but nobody needs a 32-bit anything in 2018. Then why x86-64 integer instructions default to 32-bit register size when REX prefix byte i

> That's great and all, but nobody needs a 32-bit anything in 2018. Then why x86-64 integer instructions default to 32-bit register size when REX prefix byte is not present? You can double x86 FP throughput using 32-bit floats versus 64 bit ones. For GPUs, the performance 32-bit float performance advantage can be more than 4-10x (sometimes a lot more).