- (cond
- ((sc-is y immediate)
- (let ((val (tn-value y)))
- (etypecase val
- (integer
- (if (and (zerop val) (sc-is x any-reg descriptor-reg))
- (inst test x x) ; smaller
- (inst cmp x (fixnumize val))))
- (symbol
- (inst cmp x (+ nil-value (static-symbol-offset val))))
- (character
- (inst cmp x (logior (ash (char-code val) n-widetag-bits)
- character-widetag))))))
- ((sc-is x immediate) ; and y not immediate
- ;; Swap the order to fit the compare instruction.
- (let ((val (tn-value x)))
- (etypecase val
- (integer
- (if (and (zerop val) (sc-is y any-reg descriptor-reg))
- (inst test y y) ; smaller
- (inst cmp y (fixnumize val))))
- (symbol
- (inst cmp y (+ nil-value (static-symbol-offset val))))
- (character
- (inst cmp y (logior (ash (char-code val) n-widetag-bits)
- character-widetag))))))
- (t
- (inst cmp x y)))
+ (let ((x-val (encode-value-if-immediate x))
+ (y-val (encode-value-if-immediate y)))
+ (cond
+ ;; Shorter instruction sequences for these two cases.
+ ((and (eql 0 y-val) (sc-is x any-reg descriptor-reg)) (inst test x x))
+ ((and (eql 0 x-val) (sc-is y any-reg descriptor-reg)) (inst test y y))
+
+ ;; An encoded value (literal integer) has to be the second argument.
+ ((sc-is x immediate) (inst cmp y x-val))
+
+ (t (inst cmp x y-val))))