alt Hacker NewsAnd the other way around: RISC-V doesn't have a move instruction so that's done as "dst = src + 0", and it doesn't have a nop instruction so that's done as "x0 = x0 + 0". There's like a dozen of them.
It's quite interesting what neat tricks roll out once you've got a guaranteed zero register - it greatly reduces the number of distinct instructions you need for what is basically the same operation.
Another one is "jalr x0, imm(x0)", which turns an indirect branch into a direct jump to address "imm" in a single instruction w/o clobbering a register. Pretty neat.