[xpasky]

  push 1
  pop rax

is even shorter (credit: https://old.reddit.com/r/programming/comments/q6mnz1/what_is...)

[musicale]

I feel like I shouldn't love x86 encoding, but there is something charming about this. Probably echoing its 8-bit predecessors. It seems like it's designed for tiny memory environments (embedded, bootstrapping, etc.) where you don't mind taking a hit for memory access.