Avoid emitting REX for legacy registers.
(define-instruction set (segment dst cond)
(:printer cond-set ())
(:emitter
(define-instruction set (segment dst cond)
(:printer cond-set ())
(:emitter
- (maybe-emit-rex-for-ea segment dst nil)
+ (maybe-emit-rex-for-ea segment dst nil :operand-size :byte)
(emit-byte segment #b00001111)
(emit-byte segment (dpb (conditional-opcode cond) (byte 4 0) #b10010000))
(emit-ea segment dst #b000)))
(emit-byte segment #b00001111)
(emit-byte segment (dpb (conditional-opcode cond) (byte 4 0) #b10010000))
(emit-ea segment dst #b000)))