Findings so far:
- If you put ".intel_syntax" at the top of a gas file, it does *not* give you intel syntax *or* AT&T syntax but a secret third thing. The way to get the real intel syntax is ".intel_syntax noprefix"
- It didn't accept the 0(reg) syntax to dereference. By experimentation, I found I could do 0[reg]. That is terrifying. Guessing, I mean.
- No one I have spoken to has learned intel syntax by anything other than oral tradition. Also, no one uses intel with gas (they all use nasm?)