<p>Finding many things that are just sort of It's Assumed You Know This but may or may not be written anywhere. Like, there's a "movb" instruction which is not in the instruction reference I'm using and is not recognized by my syntax highlighter, but gas accepts it.</p><p>Question. I do</p><p>mov %al, %esi</p><p>It says operand type mismatch. OK. I think I can simulate this with</p><p>mov $0, %rax<br />mov $eax, $esi</p><p>BC non-al bits of rax get cleared in instruction 1.</p><p>…But what's the "widening"/truncating version of mov?</p>
