+ ;; Use DATA-VECTOR-REF directly,
+ ;; since that's what SVREF in a
+ ;; SAFETY 0 lexenv will eventually be
+ ;; transformed to. This can give a
+ ;; large compilation speedup, since
+ ;; %INSTANCE-TYPEPs are frequently
+ ;; created during GENERATE-TYPE-CHECKS,
+ ;; and the normal aref transformation path
+ ;; is pretty heavy.
+ (eq (data-vector-ref (layout-inherits ,n-layout)
+ ,depthoid)