;;; simple.
(deftransform sxhash ((x) (fixnum))
'(logand most-positive-fixnum
- (logxor x
- (ash x -3) ; to get sign bit into hash
+ (logxor (ash (logand x (ash most-positive-fixnum -4)) 4)
+ (ash x -1) ; to get sign bit into hash
361475658)))
-;;;; Some other common SXHASH cases are defined as DEFTRANSFORMs in order to
-;;;; avoid having to do TYPECASE at runtime.
+;;; SXHASH of SIMPLE-BIT-VECTOR values is defined as a DEFTRANSFORM
+;;; because it is endian-dependent.
+(deftransform sxhash ((x) (simple-bit-vector))
+ `(let ((result 410823708))
+ (declare (type fixnum result))
+ (let ((length (length x)))
+ (cond
+ ((= length 0) (mix result (sxhash 0)))
+ (t
+ (mixf result (sxhash (length x)))
+ (do* ((i sb!vm:vector-data-offset (+ i 1))
+ ;; FIXME: should we respect DEPTHOID? SXHASH on
+ ;; strings doesn't seem to...
+ (end-1 (+ sb!vm:vector-data-offset
+ (floor (1- length) sb!vm:n-word-bits))))
+ ((= i end-1)
+ (let ((num
+ (logand
+ (ash (1- (ash 1 (mod length sb!vm:n-word-bits)))
+ ,(ecase sb!c:*backend-byte-order*
+ (:little-endian 0)
+ (:big-endian
+ '(- sb!vm:n-word-bits
+ (mod length sb!vm:n-word-bits)))))
+ (%raw-bits x i))))
+ (declare (type (unsigned-byte 32) num))
+ (mix result ,(ecase sb!c:*backend-byte-order*
+ (:little-endian
+ '(logand num most-positive-fixnum))
+ (:big-endian
+ '(ash num (- sb!vm:n-lowtag-bits)))))))
+ (declare (type index i end-1))
+ (let ((num (%raw-bits x i)))
+ (declare (type (unsigned-byte 32) num))
+ (mixf result ,(ecase sb!c:*backend-byte-order*
+ (:little-endian
+ '(logand num most-positive-fixnum))
+ ;; FIXME: I'm not certain that
+ ;; N-LOWTAG-BITS is the clearest way of
+ ;; expressing this: it's essentially the
+ ;; difference between `(UNSIGNED-BYTE
+ ;; ,SB!VM:N-WORD-BITS) and (AND FIXNUM
+ ;; UNSIGNED-BYTE).
+ (:big-endian
+ '(ash num (- sb!vm:n-lowtag-bits))))))))))))
+
+;;; Some other common SXHASH cases are defined as DEFTRANSFORMs in
+;;; order to avoid having to do TYPECASE at runtime.
+;;;
+;;; We also take the opportunity to handle the cases of constant
+;;; strings, and of symbols whose names are known at compile time;
+;;; except that since SXHASH on the cross-compilation host is not in
+;;; general compatible with SXHASH on the target SBCL, we can't so
+;;; easily do this optimization in the cross-compiler, and SBCL itself
+;;; doesn't seem to need this optimization, so we don't try.
(deftransform sxhash ((x) (simple-string))
- '(%sxhash-simple-string x))
+ (if #+sb-xc-host nil #-sb-xc-host (constant-lvar-p x)
+ (sxhash (lvar-value x))
+ '(%sxhash-simple-string x)))
(deftransform sxhash ((x) (symbol))
- '(%sxhash-simple-string (symbol-name x)))
+ (if #+sb-xc-host nil #-sb-xc-host (constant-lvar-p x)
+ (sxhash (lvar-value x))
+ '(%sxhash-simple-string (symbol-name x))))
+
+