- (move-qword-to-eax value)
- (inst and al-tn lowtag-mask)
- (inst cmp al-tn lowtag)
- (inst jmp (if not-p :ne :e) target))
+ (inst lea eax-tn (make-ea :dword :base value :disp (- lowtag)))
+ (inst test al-tn lowtag-mask)
+ (inst jmp (if not-p :nz :z) target))