Ask HN: What are some examples of beautiful x86 assembly code?
I bought a nice little booklet of small x86 gems a few years back[1][2] and this one is my favorite:  .loop:
      xadd     rax,rdx
      loop     .loop

Fibonacci with two instructions.[1] https://www.amazon.com/dp/1502958082[2] https://www.xorpd.net/pages/xchg_rax/snip_00.html