alt Hacker NewsThe non-obvious bit is why there isn't an even faster and shorter "mov <register>,0" instructions - the processors started short-circuiting xor <register>,<register> much later.
The non-obvious bit is why there isn't an even faster and shorter "mov <register>,0" instructions - the processors started short-circuiting xor <register>,<register> much later.
Right, like a “set reg to zero” instruction. One byte. Just encodes the operation and the reg to zero. I’m surprised we didn’t have it on those old processors. Maybe the thinking was that it was already there: xor reg,reg.