;;; SXHASH of FLOAT values is defined directly in terms of DEFTRANSFORM in
;;; order to avoid boxing.
(deftransform sxhash ((x) (single-float))
- '(let ((bits (single-float-bits x)))
+ '(let* ((val (+ 0.0f0 x))
+ (bits (logand (single-float-bits val) #.(1- (ash 1 32)))))
(logxor 66194023
(sxhash (the fixnum
(logand most-positive-fixnum
(logxor bits
(ash bits -7))))))))
(deftransform sxhash ((x) (double-float))
- '(let* ((val x)
- (hi (double-float-high-bits val))
+ '(let* ((val (+ 0.0d0 x))
+ (hi (logand (double-float-high-bits val) #.(1- (ash 1 32))))
(lo (double-float-low-bits val))
(hilo (logxor hi lo)))
(logxor 475038542
;;; 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)
+ (logand (ash x -1) most-positive-fixnum) ; 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))))
+ (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)))
+ (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))
+ (if (csubtypep (lvar-type x) (specifier-type 'null))
+ ;; FIXME: this isn't in fact as optimized as it could be;
+ ;; this does a memory load, whereas (because we know the
+ ;; layout of NIL) we could simply take the address of NIL
+ ;; (or the contents of NULL-TN) and mask off the appropriate
+ ;; bits, since SYMBOL-HASH of NIL is also NIL's CDR, which
+ ;; is NIL. -- CSR, 2004-07-14
+ '(symbol-hash x)
+ ;; Cache the value of the symbol's sxhash in the symbol-hash
+ ;; slot.
+ '(let ((result (symbol-hash x)))
+ ;; 0 marks uninitialized slot. We can't use negative
+ ;; values for the uninitialized slots since NIL might be
+ ;; located so high in memory on some platforms that its
+ ;; SYMBOL-HASH (which contains NIL itself) is a negative
+ ;; fixnum.
+ (if (= 0 result)
+ (let ((sxhash (%sxhash-simple-string (symbol-name x))))
+ ;; We could do a (logior sxhash #x10000000) to
+ ;; ensure that we never store a 0 in the
+ ;; slot. However, it's such an unlikely event
+ ;; (1/5e8?) that it makes more sense to optimize for
+ ;; the common case...
+ (%set-symbol-hash x sxhash)
+ sxhash)
+ result)))))
projects / sbcl.git / blobdiff