+(!def-vm-support-routine combination-implementation-style (node)
+ (declare (type sb!c::combination node))
+ (flet ((valid-funtype (args result)
+ (sb!c::valid-fun-use node
+ (sb!c::specifier-type
+ `(function ,args ,result)))))
+ (case (sb!c::combination-fun-source-name node)
+ (logtest
+ (cond
+ ((or (valid-funtype '(fixnum fixnum) '*)
+ (valid-funtype '((signed-byte 32) (signed-byte 32)) '*)
+ (valid-funtype '((unsigned-byte 32) (unsigned-byte 32)) '*))
+ (values :direct nil))
+ (t (values :default nil))))
+ (logbitp
+ (cond
+ ((or (valid-funtype '((constant-arg (integer 0 29)) fixnum) '*)
+ (valid-funtype '((constant-arg (integer 0 31)) (signed-byte 32)) '*)
+ (valid-funtype '((constant-arg (integer 0 31)) (unsigned-byte 32)) '*))
+ (values :transform '(lambda (index integer)
+ (%logbitp integer index))))
+ (t (values :default nil))))
+ ;; FIXME: can handle MIN and MAX here
+ (sb!kernel:%ldb
+ (cond
+ ((or (valid-funtype '((constant-arg (integer 1 29))
+ (constant-arg (integer 0 29))
+ fixnum)
+ 'fixnum)
+ (valid-funtype '((constant-arg (integer 1 29))
+ (constant-arg (integer 0 29))
+ (signed-byte 32))
+ 'fixnum)
+ (valid-funtype '((constant-arg (integer 1 29))
+ (constant-arg (integer 0 29))
+ (unsigned-byte 32))
+ 'fixnum))
+ (values :transform
+ '(lambda (size posn integer)
+ (%%ldb integer size posn))))
+ (t (values :default nil))))
+ (t (values :default nil)))))