vm-tran.lisp

开源跨平台Lisp编译器

          (incf count (logcount (%raw-bits sequence index)))))))

(deftransform fill ((sequence item) (simple-bit-vector bit) *
                    :policy (>= speed space))
  (let ((value (if (constant-lvar-p item)
                   (if (= (lvar-value item) 0)
                       0
                       #.(1- (ash 1 sb!vm:n-word-bits)))
                   `(if (= item 0) 0 #.(1- (ash 1 sb!vm:n-word-bits))))))
    `(let ((length (length sequence))
           (value ,value))
       (if (= length 0)
           sequence
           (do ((index sb!vm:vector-data-offset (1+ index))
                (end-1 (+ sb!vm:vector-data-offset
                          ;; bit-vectors of length 1 to n-word-bits need
                          ;; precisely one (SETF %RAW-BITS), done here
                          ;; in the epilogue. - CSR, 2002-04-24
                          (truncate (truly-the index (1- length))
                                    sb!vm:n-word-bits))))
               ((>= index end-1)
                (setf (%raw-bits sequence index) value)
                sequence)
             (declare (optimize (speed 3) (safety 0))
                      (type index index end-1))
             (setf (%raw-bits sequence index) value))))))

(deftransform fill ((sequence item) (simple-base-string base-char) *
                    :policy (>= speed space))
  (let ((value (if (constant-lvar-p item)
                   (let* ((char (lvar-value item))
                          (code (sb!xc:char-code char))
                          (accum 0))
                     (dotimes (i sb!vm:n-word-bytes accum)
                       (setf accum (logior accum (ash code (* 8 i))))))
                   `(let ((code (sb!xc:char-code item)))
                     (logior ,@(loop for i from 0 below sb!vm:n-word-bytes
                                     collect `(ash code ,(* 8 i))))))))
    `(let ((length (length sequence))
           (value ,value))
      (multiple-value-bind (times rem)
          (truncate length sb!vm:n-word-bytes)
        (do ((index sb!vm:vector-data-offset (1+ index))
             (end (+ times sb!vm:vector-data-offset)))
            ((>= index end)
             (let ((place (* times sb!vm:n-word-bytes)))
               (declare (fixnum place))
               (dotimes (j rem sequence)
                 (declare (index j))
                 (setf (schar sequence (the index (+ place j))) item))))
          (declare (optimize (speed 3) (safety 0))
                   (type index index))
          (setf (%raw-bits sequence index) value))))))

;;;; %BYTE-BLT

;;; FIXME: The old CMU CL code used various COPY-TO/FROM-SYSTEM-AREA
;;; stuff (with all the associated bit-index cruft and overflow
;;; issues) even for byte moves. In SBCL, we're converting to byte
;;; moves as problems are discovered with the old code, and this is
;;; currently (ca. sbcl-0.6.12.30) the main interface for code in
;;; SB!KERNEL and SB!SYS (e.g. i/o code). It's not clear that it's the
;;; ideal interface, though, and it probably deserves some thought.
(deftransform %byte-blt ((src src-start dst dst-start dst-end)
                         ((or (simple-unboxed-array (*)) system-area-pointer)
                          index
                          (or (simple-unboxed-array (*)) system-area-pointer)
                          index
                          index))
  ;; FIXME: CMU CL had a hairier implementation of this (back when it
  ;; was still called (%PRIMITIVE BYTE-BLT). It had the small problem
  ;; that it didn't work for large (>16M) values of SRC-START or
  ;; DST-START. However, it might have been more efficient. In
  ;; particular, I don't really know how much the foreign function
  ;; call costs us here. My guess is that if the overhead is
  ;; acceptable for SQRT and COS, it's acceptable here, but this
  ;; should probably be checked. -- WHN
  '(flet ((sapify (thing)
            (etypecase thing
              (system-area-pointer thing)
              ;; FIXME: The code here rather relies on the simple
              ;; unboxed array here having byte-sized entries. That
              ;; should be asserted explicitly, I just haven't found
              ;; a concise way of doing it. (It would be nice to
              ;; declare it in the DEFKNOWN too.)
              ((simple-unboxed-array (*)) (vector-sap thing)))))
     (declare (inline sapify))
    (with-pinned-objects (dst src)
      (memmove (sap+ (sapify dst) dst-start)
               (sap+ (sapify src) src-start)
               (- dst-end dst-start)))
     (values)))

;;;; transforms for EQL of floating point values

(deftransform eql ((x y) (single-float single-float))
  '(= (single-float-bits x) (single-float-bits y)))

(deftransform eql ((x y) (double-float double-float))
  '(and (= (double-float-low-bits x) (double-float-low-bits y))
        (= (double-float-high-bits x) (double-float-high-bits y))))


;;;; modular functions
;;;
;;; FIXME: I think that the :GOODness of a modular function boils down
;;; to whether the normal definition can be used in the middle of a
;;; modular arrangement.  LOGAND and LOGIOR can be for all unsigned
;;; modular implementations, I believe, because for all unsigned
;;; arguments of a given size the result of the ordinary definition is
;;; the right one.  This should follow through to other logical
;;; functions, such as LOGXOR, should it not?  -- CSR, 2007-12-29,
;;; trying to understand a comment he wrote over four years
;;; previously: "FIXME: XOR? ANDC1, ANDC2?  -- CSR, 2003-09-16"
(define-good-modular-fun logand :untagged nil)
(define-good-modular-fun logior :untagged nil)
(define-good-modular-fun logxor :untagged nil)
(macrolet ((define-good-signed-modular-funs (&rest funs)
             (let (result)
               `(progn
                 ,@(dolist (fun funs (nreverse result))
                     (push `(define-good-modular-fun ,fun :untagged t) result)
                     (push `(define-good-modular-fun ,fun :tagged t) result))))))
  (define-good-signed-modular-funs
      logand logandc1 logandc2 logeqv logior lognand lognor lognot
      logorc1 logorc2 logxor))

(macrolet
    ((def (name kind width signedp)
       (let ((type (ecase signedp
                     ((nil) 'unsigned-byte)
                     ((t) 'signed-byte))))
         `(progn
            (defknown ,name (integer (integer 0)) (,type ,width)
                      (foldable flushable movable))
            (define-modular-fun-optimizer ash ((integer count) ,kind ,signedp :width width)
              (when (and (<= width ,width)
                         (or (and (constant-lvar-p count)
                                  (plusp (lvar-value count)))
                             (csubtypep (lvar-type count)
                                        (specifier-type '(and unsigned-byte fixnum)))))
                (cut-to-width integer ,kind width ,signedp)
                ',name))
            (setf (gethash ',name (modular-class-versions (find-modular-class ',kind ',signedp)))
                  `(ash ,',width))))))
  ;; This should really be dependent on SB!VM:N-WORD-BITS, but since we
  ;; don't have a true Alpha64 port yet, we'll have to stick to
  ;; SB!VM:N-MACHINE-WORD-BITS for the time being.  --njf, 2004-08-14
  #!+#.(cl:if (cl:= 32 sb!vm:n-machine-word-bits) '(and) '(or))
  (progn
    #!+x86 (def sb!vm::ash-left-smod30 :tagged 30 t)
    (def sb!vm::ash-left-mod32 :untagged 32 nil))
  #!+#.(cl:if (cl:= 64 sb!vm:n-machine-word-bits) '(and) '(or))
  (progn
    #!+x86-64 (def sb!vm::ash-left-smod61 :tagged 61 t)
    (def sb!vm::ash-left-mod64 :untagged 64 nil)))

;;;; word-wise logical operations

;;; These transforms assume the presence of modular arithmetic to
;;; generate efficient code.

(define-source-transform word-logical-not (x)
  `(logand (lognot (the sb!vm:word ,x)) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-and ((x y))
  '(logand x y))

(deftransform word-logical-nand ((x y))
  '(logand (lognand x y) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-or ((x y))
  '(logior x y))

(deftransform word-logical-nor ((x y))
  '(logand (lognor x y) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-xor ((x y))
  '(logxor x y))

(deftransform word-logical-eqv ((x y))
  '(logand (logeqv x y) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-orc1 ((x y))
  '(logand (logorc1 x y) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-orc2 ((x y))
  '(logand (logorc2 x y) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-andc1 ((x y))
  '(logand (logandc1 x y) #.(1- (ash 1 sb!vm:n-word-bits))))

(deftransform word-logical-andc2 ((x y))
  '(logand (logandc2 x y) #.(1- (ash 1 sb!vm:n-word-bits))))


;;; There are two different ways the multiplier can be recoded. The
;;; more obvious is to shift X by the correct amount for each bit set
;;; in Y and to sum the results. But if there is a string of bits that
;;; are all set, you can add X shifted by one more then the bit
;;; position of the first set bit and subtract X shifted by the bit
;;; position of the last set bit. We can't use this second method when
;;; the high order bit is bit 31 because shifting by 32 doesn't work
;;; too well.
(defun ub32-strength-reduce-constant-multiply (arg num)
  (declare (type (unsigned-byte 32) num))
  (let ((adds 0) (shifts 0)
        (result nil) first-one)
    (labels ((add (next-factor)
               (setf result
                     (if result
                         (progn (incf adds) `(+ ,result ,next-factor))
                         next-factor))))
      (declare (inline add))
      (dotimes (bitpos 32)
        (if first-one
            (when (not (logbitp bitpos num))
              (add (if (= (1+ first-one) bitpos)
                       ;; There is only a single bit in the string.
                       (progn (incf shifts) `(ash ,arg ,first-one))
                       ;; There are at least two.
                       (progn
                         (incf adds)
                         (incf shifts 2)
                         `(- (ash ,arg ,bitpos)
                             (ash ,arg ,first-one)))))
              (setf first-one nil))
            (when (logbitp bitpos num)
              (setf first-one bitpos))))
      (when first-one
        (cond ((= first-one 31))
              ((= first-one 30) (incf shifts) (add `(ash ,arg 30)))
              (t
               (incf shifts 2)
               (incf adds)
               (add `(- (ash ,arg 31)
                        (ash ,arg ,first-one)))))
        (incf shifts)
        (add `(ash ,arg 31))))
    (values (if (plusp adds)
                `(logand ,result #.(1- (ash 1 32))) ; using modular arithmetic
                result)
            adds
            shifts)))


;;; Transform GET-LISP-OBJ-ADDRESS for constant immediates, since the normal
;;; VOP can't handle them.

(deftransform sb!vm::get-lisp-obj-address ((obj) ((constant-arg fixnum)))
  (ash (lvar-value obj) sb!vm::n-fixnum-tag-bits))

(deftransform sb!vm::get-lisp-obj-address ((obj) ((constant-arg character)))
  (logior sb!vm::character-widetag
          (ash (char-code (lvar-value obj)) sb!vm::n-widetag-bits)))