(frob (simple-array (unsigned-byte 2) (*)) 2)
(frob (simple-array (unsigned-byte 4) (*)) 4))
\f
-;;;; simple string transforms
-;;;;
-;;;; Note: CMU CL had more of these, including transforms for
-;;;; functions which cons. In SBCL, we've gotten rid of the transforms
-;;;; for functions which cons, since our GC overhead is sufficiently
-;;;; large that it doesn't seem worth it to try to economize on
-;;;; function call overhead or on the overhead of runtime type
-;;;; dispatch in AREF.
-
-;;; FIXME: Shouldn't we be testing for legality of
-;;; * START1, START2, END1, and END2 indices?
-;;; * size of copied string relative to destination string?
-;;; (Either there should be tests conditional on SAFETY>=SPEED, or
-;;; the transform should be conditional on SPEED>SAFETY.)
-;;;
-;;; FIXME: Also, the transform should probably be dependent on
-;;; SPEED>SPACE.
-(deftransform replace ((string1 string2 &key (start1 0) (start2 0)
- end1 end2)
- (simple-string simple-string &rest t))
- `(locally
- (declare (optimize (safety 0)))
- (bit-bash-copy string2
- (the index
- (+ (the index (* start2 sb!vm:byte-bits))
- ,vector-data-bit-offset))
- string1
- (the index
- (+ (the index (* start1 sb!vm:byte-bits))
- ,vector-data-bit-offset))
- (the index
- (* (min (the index (- (or end1 (length string1))
- start1))
- (the index (- (or end2 (length string2))
- start2)))
- sb!vm:byte-bits)))
- string1))
-\f
;;;; bit vector hackery
;;; SIMPLE-BIT-VECTOR bit-array operations are transformed to a word loop that
(sb!impl::%sp-string-compare
string1 start1 (or end1 (length string1))
string2 start2 (or end2 (length string2)))))))
+\f
+;;;; string-only transforms for sequence functions
+;;;;
+;;;; Note: CMU CL had more of these, including transforms for
+;;;; functions which cons. In SBCL, we've gotten rid of most of the
+;;;; transforms for functions which cons, since our GC overhead is
+;;;; sufficiently large that it doesn't seem worth it to try to
+;;;; economize on function call overhead or on the overhead of runtime
+;;;; type dispatch in AREF. The exception is CONCATENATE, since
+;;;; a full call to CONCATENATE would have to look up the sequence
+;;;; type, which can be really slow.
+;;;;
+;;;; FIXME: It would be nicer for these transforms to work for any
+;;;; calls when all arguments are vectors with the same element type,
+;;;; rather than restricting them to STRINGs only.
+
+;;; FIXME: Shouldn't we be testing for legality of
+;;; * START1, START2, END1, and END2 indices?
+;;; * size of copied string relative to destination string?
+;;; (Either there should be tests conditional on SAFETY>=SPEED, or
+;;; the transform should be conditional on SPEED>SAFETY.)
+;;;
+;;; FIXME: Also, the transform should probably be dependent on
+;;; SPEED>SPACE.
+(deftransform replace ((string1 string2 &key (start1 0) (start2 0)
+ end1 end2)
+ (simple-string simple-string &rest t))
+ `(locally
+ (declare (optimize (safety 0)))
+ (bit-bash-copy string2
+ (the index
+ (+ (the index (* start2 sb!vm:byte-bits))
+ ,vector-data-bit-offset))
+ string1
+ (the index
+ (+ (the index (* start1 sb!vm:byte-bits))
+ ,vector-data-bit-offset))
+ (the index
+ (* (min (the index (- (or end1 (length string1))
+ start1))
+ (the index (- (or end2 (length string2))
+ start2)))
+ sb!vm:byte-bits)))
+ string1))
+
+;;; FIXME: It seems as though it should be possible to make a DEFUN
+;;; %CONCATENATE (with a DEFTRANSFORM to translate constant RTYPE to
+;;; CTYPE before calling %CONCATENATE) which is comparably efficient,
+;;; at least once DYNAMIC-EXTENT works.
+(deftransform concatenate ((rtype &rest sequences)
+ (t &rest simple-string)
+ simple-string)
+ (collect ((lets)
+ (forms)
+ (all-lengths)
+ (args))
+ (dolist (seq sequences)
+ (declare (ignore seq))
+ (let ((n-seq (gensym))
+ (n-length (gensym)))
+ (args n-seq)
+ (lets `(,n-length (the index (* (length ,n-seq) sb!vm:byte-bits))))
+ (all-lengths n-length)
+ (forms `(bit-bash-copy ,n-seq ,vector-data-bit-offset
+ res start
+ ,n-length))
+ (forms `(setq start (+ start ,n-length)))))
+ `(lambda (rtype ,@(args))
+ (declare (ignore rtype))
+ (let* (,@(lets)
+ (res (make-string (truncate (the index (+ ,@(all-lengths)))
+ sb!vm:byte-bits)))
+ (start ,vector-data-bit-offset))
+ (declare (type index start ,@(all-lengths)))
+ ,@(forms)
+ res))))