[jcranmer]

Seeing that reminds me of one of the projects I want to do: the "World's Worst x86 Decoder". The basic idea is you toss most of the x86 manual, and just consider all of the prefixes as part of the opcode, so you say that x86 has (numbers are top of head, may be inaccurate) N opcodes, where N = 256 * 4 opcode maps * 4 group 1 prefix possibilities * 7 group 2 prefix * 2 group 3 * 2 group 4 * {REX/VEX/EVEX prefix counting is hard to do). It's the "world's worst" decoder, because not only does it not try to actually give a human-readable name for the opcode, it is also going to give patently wrong results for cases where "we packed 8 different instructions into this opcode, because they each take a memory argument, so the other R field in the ModR/M byte chooses a different instruction".