src/compiler/generic/vm-tran.lisp

   1 ;;;; implementation-dependent transforms
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; This software is derived from the CMU CL system, which was
   7 ;;;; written at Carnegie Mellon University and released into the
   8 ;;;; public domain. The software is in the public domain and is
   9 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  10 ;;;; files for more information.
  11
  12 (in-package "SB!C")
  13
  14 ;;; We need to define these predicates, since the TYPEP source
  15 ;;; transform picks whichever predicate was defined last when there
  16 ;;; are multiple predicates for equivalent types.
  17 (define-source-transform short-float-p (x) `(single-float-p ,x))
  18 #!-long-float
  19 (define-source-transform long-float-p (x) `(double-float-p ,x))
  20
  21 (define-source-transform compiled-function-p (x)
  22   #!-sb-eval
  23   `(functionp ,x)
  24   #!+sb-eval
  25   (once-only ((x x))
  26     `(and (functionp ,x)
  27           (not (sb!eval:interpreted-function-p ,x)))))
  28
  29 (define-source-transform char-int (x)
  30   `(char-code ,x))
  31
  32 (deftransform abs ((x) (rational))
  33   '(if (< x 0) (- x) x))
  34
  35 ;;; We don't want to clutter the bignum code.
  36 #!+(or x86 x86-64)
  37 (define-source-transform sb!bignum:%bignum-ref (bignum index)
  38   ;; KLUDGE: We use TRULY-THE here because even though the bignum code
  39   ;; is (currently) compiled with (SAFETY 0), the compiler insists on
  40   ;; inserting CAST nodes to ensure that INDEX is of the correct type.
  41   ;; These CAST nodes do not generate any type checks, but they do
  42   ;; interfere with the operation of FOLD-INDEX-ADDRESSING, below.
  43   ;; This scenario is a problem for the more user-visible case of
  44   ;; folding as well.  --njf, 2006-12-01
  45   `(sb!bignum:%bignum-ref-with-offset ,bignum
  46                                       (truly-the bignum-index ,index) 0))
  47
  48 #!+(or x86 x86-64)
  49 (defun fold-index-addressing (fun-name element-size lowtag data-offset
  50                               index offset &optional setter-p)
  51   (multiple-value-bind (func index-args) (extract-fun-args index '(+ -) 2)
  52     (destructuring-bind (x constant) index-args
  53       (declare (ignorable x))
  54       (unless (constant-lvar-p constant)
  55         (give-up-ir1-transform))
  56       (let ((value (lvar-value constant)))
  57         (unless (and (integerp value)
  58                      (sb!vm::foldable-constant-offset-p
  59                       element-size lowtag data-offset
  60                       (funcall func value (lvar-value offset))))
  61           (give-up-ir1-transform "constant is too large for inlining"))
  62         (splice-fun-args index func 2)
  63         `(lambda (thing index off1 off2 ,@(when setter-p
  64                                             '(value)))
  65            (,fun-name thing index (,func off2 off1) ,@(when setter-p
  66                                                         '(value))))))))
  67
  68 #!+(or x86 x86-64)
  69 (deftransform sb!bignum:%bignum-ref-with-offset
  70     ((bignum index offset) * * :node node)
  71   (fold-index-addressing 'sb!bignum:%bignum-ref-with-offset
  72                          sb!vm:n-word-bits sb!vm:other-pointer-lowtag
  73                          sb!vm:bignum-digits-offset
  74                          index offset))
  75
  76 #!+x86
  77 (progn
  78 (define-source-transform sb!kernel:%vector-raw-bits (thing index)
  79   `(sb!kernel:%raw-bits-with-offset ,thing ,index 2))
  80
  81 (define-source-transform sb!kernel:%raw-bits (thing index)
  82   `(sb!kernel:%raw-bits-with-offset ,thing ,index 0))
  83
  84 (define-source-transform sb!kernel:%set-vector-raw-bits (thing index value)
  85   `(sb!kernel:%set-raw-bits-with-offset ,thing ,index 2 ,value))
  86
  87 (define-source-transform sb!kernel:%set-raw-bits (thing index value)
  88   `(sb!kernel:%set-raw-bits-with-offset ,thing ,index 0 ,value))
  89
  90 (deftransform sb!kernel:%raw-bits-with-offset ((thing index offset) * * :node node)
  91   (fold-index-addressing 'sb!kernel:%raw-bits-with-offset
  92                          sb!vm:n-word-bits sb!vm:other-pointer-lowtag
  93                          0 index offset))
  94
  95 (deftransform sb!kernel:%set-raw-bits-with-offset ((thing index offset value) * *)
  96   (fold-index-addressing 'sb!kernel:%set-raw-bits-with-offset
  97                          sb!vm:n-word-bits sb!vm:other-pointer-lowtag
  98                          0 index offset t))
  99 ) ; PROGN
 100
 101 ;;; The layout is stored in slot 0.
 102 (define-source-transform %instance-layout (x)
 103   `(truly-the layout (%instance-ref ,x 0)))
 104 (define-source-transform %set-instance-layout (x val)
 105   `(%instance-set ,x 0 (the layout ,val)))
 106 (define-source-transform %funcallable-instance-layout (x)
 107   `(truly-the layout (%funcallable-instance-info ,x 0)))
 108 (define-source-transform %set-funcallable-instance-layout (x val)
 109   `(setf (%funcallable-instance-info ,x 0) (the layout ,val)))
 110 \f
 111 ;;;; character support
 112
 113 ;;; In our implementation there are really only BASE-CHARs.
 114 #+nil
 115 (define-source-transform characterp (obj)
 116   `(base-char-p ,obj))
 117 \f
 118 ;;;; simplifying HAIRY-DATA-VECTOR-REF and HAIRY-DATA-VECTOR-SET
 119
 120 (deftransform hairy-data-vector-ref ((string index) (simple-string t))
 121   (let ((ctype (lvar-type string)))
 122     (if (array-type-p ctype)
 123         ;; the other transform will kick in, so that's OK
 124         (give-up-ir1-transform)
 125         `(etypecase string
 126           ((simple-array character (*))
 127            (data-vector-ref string index))
 128           #!+sb-unicode
 129           ((simple-array base-char (*))
 130            (data-vector-ref string index))
 131           ((simple-array nil (*))
 132            (data-vector-ref string index))))))
 133
 134 (deftransform hairy-data-vector-ref ((array index) (array t) *)
 135   "avoid runtime dispatch on array element type"
 136   (let ((element-ctype (extract-upgraded-element-type array))
 137         (declared-element-ctype (extract-declared-element-type array)))
 138     (declare (type ctype element-ctype))
 139     (when (eq *wild-type* element-ctype)
 140       (give-up-ir1-transform
 141        "Upgraded element type of array is not known at compile time."))
 142     ;; (The expansion here is basically a degenerate case of
 143     ;; WITH-ARRAY-DATA. Since WITH-ARRAY-DATA is implemented as a
 144     ;; macro, and macros aren't expanded in transform output, we have
 145     ;; to hand-expand it ourselves.)
 146     (let* ((element-type-specifier (type-specifier element-ctype)))
 147       `(multiple-value-bind (array index)
 148            (%data-vector-and-index array index)
 149          (declare (type (simple-array ,element-type-specifier 1) array))
 150          ,(let ((bare-form '(data-vector-ref array index)))
 151             (if (type= element-ctype declared-element-ctype)
 152                 bare-form
 153                 `(the ,(type-specifier declared-element-ctype)
 154                       ,bare-form)))))))
 155
 156 ;;; Transform multi-dimensional array to one dimensional data vector
 157 ;;; access.
 158 (deftransform data-vector-ref ((array index) (simple-array t))
 159   (let ((array-type (lvar-type array)))
 160     (unless (array-type-p array-type)
 161       (give-up-ir1-transform))
 162     (let ((dims (array-type-dimensions array-type)))
 163       (when (or (atom dims) (= (length dims) 1))
 164         (give-up-ir1-transform))
 165       (let ((el-type (array-type-specialized-element-type array-type))
 166             (total-size (if (member '* dims)
 167                             '*
 168                             (reduce #'* dims))))
 169         `(data-vector-ref (truly-the (simple-array ,(type-specifier el-type)
 170                                                    (,total-size))
 171                                      (%array-data-vector array))
 172                           index)))))
 173
 174 ;;; Transform data vector access to a form that opens up optimization
 175 ;;; opportunities. On platforms that support DATA-VECTOR-REF-WITH-OFFSET
 176 ;;; DATA-VECTOR-REF is not supported at all.
 177 #!+(or x86 x86-64)
 178 (define-source-transform data-vector-ref (array index)
 179   `(data-vector-ref-with-offset ,array ,index 0))
 180
 181 #!+(or x86 x86-64)
 182 (deftransform data-vector-ref-with-offset ((array index offset))
 183   (let ((array-type (lvar-type array)))
 184     (when (or (not (array-type-p array-type))
 185               (eql (array-type-specialized-element-type array-type)
 186                    *wild-type*))
 187       (give-up-ir1-transform))
 188     ;; It shouldn't be possible to get here with anything but a non-complex
 189     ;; vector.
 190     (aver (not (array-type-complexp array-type)))
 191     (let* ((element-type (type-specifier (array-type-specialized-element-type array-type)))
 192            (saetp (find-saetp element-type)))
 193       (when (< (sb!vm:saetp-n-bits saetp) sb!vm:n-byte-bits)
 194         (give-up-ir1-transform))
 195       (fold-index-addressing 'data-vector-ref-with-offset
 196                              (sb!vm:saetp-n-bits saetp)
 197                              sb!vm:other-pointer-lowtag
 198                              sb!vm:vector-data-offset
 199                              index offset))))
 200
 201 (deftransform hairy-data-vector-set ((string index new-value)
 202                                      (simple-string t t))
 203   (let ((ctype (lvar-type string)))
 204     (if (array-type-p ctype)
 205         ;; the other transform will kick in, so that's OK
 206         (give-up-ir1-transform)
 207         `(etypecase string
 208           ((simple-array character (*))
 209            (data-vector-set string index new-value))
 210           #!+sb-unicode
 211           ((simple-array base-char (*))
 212            (data-vector-set string index new-value))
 213           ((simple-array nil (*))
 214            (data-vector-set string index new-value))))))
 215
 216 (deftransform hairy-data-vector-set ((array index new-value)
 217                                      (array t t)
 218                                      *)
 219   "avoid runtime dispatch on array element type"
 220   (let ((element-ctype (extract-upgraded-element-type array))
 221         (declared-element-ctype (extract-declared-element-type array)))
 222     (declare (type ctype element-ctype))
 223     (when (eq *wild-type* element-ctype)
 224       (give-up-ir1-transform
 225        "Upgraded element type of array is not known at compile time."))
 226     (let ((element-type-specifier (type-specifier element-ctype)))
 227       `(multiple-value-bind (array index)
 228            (%data-vector-and-index array index)
 229          (declare (type (simple-array ,element-type-specifier 1) array)
 230                   (type ,element-type-specifier new-value))
 231          ,(if (type= element-ctype declared-element-ctype)
 232               '(data-vector-set array index new-value)
 233               `(truly-the ,(type-specifier declared-element-ctype)
 234                  (data-vector-set array index
 235                   (the ,(type-specifier declared-element-ctype)
 236                        new-value))))))))
 237
 238 ;;; Transform multi-dimensional array to one dimensional data vector
 239 ;;; access.
 240 (deftransform data-vector-set ((array index new-value)
 241                                (simple-array t t))
 242   (let ((array-type (lvar-type array)))
 243     (unless (array-type-p array-type)
 244       (give-up-ir1-transform))
 245     (let ((dims (array-type-dimensions array-type)))
 246       (when (or (atom dims) (= (length dims) 1))
 247         (give-up-ir1-transform))
 248       (let ((el-type (array-type-specialized-element-type array-type))
 249             (total-size (if (member '* dims)
 250                             '*
 251                             (reduce #'* dims))))
 252         `(data-vector-set (truly-the (simple-array ,(type-specifier el-type)
 253                                                    (,total-size))
 254                                      (%array-data-vector array))
 255                           index
 256                           new-value)))))
 257
 258 ;;; Transform data vector access to a form that opens up optimization
 259 ;;; opportunities.
 260 #!+(or x86 x86-64)
 261 (define-source-transform data-vector-set (array index new-value)
 262   `(data-vector-set-with-offset ,array ,index 0 ,new-value))
 263
 264 #!+(or x86 x86-64)
 265 (deftransform data-vector-set-with-offset ((array index offset new-value))
 266   (let ((array-type (lvar-type array)))
 267     (when (or (not (array-type-p array-type))
 268               (eql (array-type-specialized-element-type array-type)
 269                    *wild-type*))
 270       ;; We don't yet know the exact element type, but will get that
 271       ;; knowledge after some more type propagation.
 272       (give-up-ir1-transform))
 273     (aver (not (array-type-complexp array-type)))
 274     (let* ((element-type (type-specifier (array-type-specialized-element-type array-type)))
 275            (saetp (find-saetp element-type)))
 276       (when (< (sb!vm:saetp-n-bits saetp) sb!vm:n-byte-bits)
 277         (give-up-ir1-transform))
 278       (fold-index-addressing 'data-vector-set-with-offset
 279                              (sb!vm:saetp-n-bits saetp)
 280                              sb!vm:other-pointer-lowtag
 281                              sb!vm:vector-data-offset
 282                              index offset t))))
 283
 284 (defoptimizer (%data-vector-and-index derive-type) ((array index))
 285   (let ((atype (lvar-type array)))
 286     (when (array-type-p atype)
 287       (values-specifier-type
 288        `(values (simple-array ,(type-specifier
 289                                 (array-type-specialized-element-type atype))
 290                               (*))
 291                 index)))))
 292
 293 (deftransform %data-vector-and-index ((%array %index)
 294                                       (simple-array t)
 295                                       *)
 296   ;; KLUDGE: why the percent signs?  Well, ARRAY and INDEX are
 297   ;; respectively exported from the CL and SB!INT packages, which
 298   ;; means that they're visible to all sorts of things.  If the
 299   ;; compiler can prove that the call to ARRAY-HEADER-P, below, either
 300   ;; returns T or NIL, it will delete the irrelevant branch.  However,
 301   ;; user code might have got here with a variable named CL:ARRAY, and
 302   ;; quite often compiler code with a variable named SB!INT:INDEX, so
 303   ;; this can generate code deletion notes for innocuous user code:
 304   ;; (DEFUN F (ARRAY I) (DECLARE (SIMPLE-VECTOR ARRAY)) (AREF ARRAY I))
 305   ;; -- CSR, 2003-04-01
 306
 307   ;; We do this solely for the -OR-GIVE-UP side effect, since we want
 308   ;; to know that the type can be figured out in the end before we
 309   ;; proceed, but we don't care yet what the type will turn out to be.
 310   (upgraded-element-type-specifier-or-give-up %array)
 311
 312   '(if (array-header-p %array)
 313        (values (%array-data-vector %array) %index)
 314        (values %array %index)))
 315
 316 ;;; transforms for getting at simple arrays of (UNSIGNED-BYTE N) when (< N 8)
 317 ;;;
 318 ;;; FIXME: In CMU CL, these were commented out with #+NIL. Why? Should
 319 ;;; we fix them or should we delete them? (Perhaps these definitions
 320 ;;; predate the various DATA-VECTOR-REF-FOO VOPs which have
 321 ;;; (:TRANSLATE DATA-VECTOR-REF), and are redundant now?)
 322 #+nil
 323 (macrolet
 324     ((frob (type bits)
 325        (let ((elements-per-word (truncate sb!vm:n-word-bits bits)))
 326          `(progn
 327             (deftransform data-vector-ref ((vector index)
 328                                            (,type *))
 329               `(multiple-value-bind (word bit)
 330                    (floor index ,',elements-per-word)
 331                  (ldb ,(ecase sb!vm:target-byte-order
 332                          (:little-endian '(byte ,bits (* bit ,bits)))
 333                          (:big-endian '(byte ,bits (- sb!vm:n-word-bits
 334                                                       (* (1+ bit) ,bits)))))
 335                       (%raw-bits vector (+ word sb!vm:vector-data-offset)))))
 336             (deftransform data-vector-set ((vector index new-value)
 337                                            (,type * *))
 338               `(multiple-value-bind (word bit)
 339                    (floor index ,',elements-per-word)
 340                  (setf (ldb ,(ecase sb!vm:target-byte-order
 341                                (:little-endian '(byte ,bits (* bit ,bits)))
 342                                (:big-endian
 343                                 '(byte ,bits (- sb!vm:n-word-bits
 344                                                 (* (1+ bit) ,bits)))))
 345                             (%raw-bits vector (+ word sb!vm:vector-data-offset)))
 346                        new-value)))))))
 347   (frob simple-bit-vector 1)
 348   (frob (simple-array (unsigned-byte 2) (*)) 2)
 349   (frob (simple-array (unsigned-byte 4) (*)) 4))
 350 \f
 351 ;;;; BIT-VECTOR hackery
 352
 353 ;;; SIMPLE-BIT-VECTOR bit-array operations are transformed to a word
 354 ;;; loop that does 32 bits at a time.
 355 ;;;
 356 ;;; FIXME: This is a lot of repeatedly macroexpanded code. It should
 357 ;;; be a function call instead.
 358 (macrolet ((def (bitfun wordfun)
 359              `(deftransform ,bitfun ((bit-array-1 bit-array-2 result-bit-array)
 360                                      (simple-bit-vector
 361                                       simple-bit-vector
 362                                       simple-bit-vector)
 363                                      *
 364                                      :node node :policy (>= speed space))
 365                 `(progn
 366                    ,@(unless (policy node (zerop safety))
 367                              '((unless (= (length bit-array-1)
 368                                           (length bit-array-2)
 369                                           (length result-bit-array))
 370                                  (error "Argument and/or result bit arrays are not the same length:~
 371                          ~%  ~S~%  ~S  ~%  ~S"
 372                                         bit-array-1
 373                                         bit-array-2
 374                                         result-bit-array))))
 375                   (let ((length (length result-bit-array)))
 376                     (if (= length 0)
 377                         ;; We avoid doing anything to 0-length
 378                         ;; bit-vectors, or rather, the memory that
 379                         ;; follows them. Other divisible-by-32 cases
 380                         ;; are handled by the (1- length), below.
 381                         ;; CSR, 2002-04-24
 382                         result-bit-array
 383                         (do ((index sb!vm:vector-data-offset (1+ index))
 384                              (end-1 (+ sb!vm:vector-data-offset
 385                                        ;; bit-vectors of length 1-32
 386                                        ;; need precisely one (SETF
 387                                        ;; %RAW-BITS), done here in the
 388                                        ;; epilogue. - CSR, 2002-04-24
 389                                        (truncate (truly-the index (1- length))
 390                                                  sb!vm:n-word-bits))))
 391                             ((>= index end-1)
 392                              (setf (%raw-bits result-bit-array index)
 393                                    (,',wordfun (%raw-bits bit-array-1 index)
 394                                                (%raw-bits bit-array-2 index)))
 395                              result-bit-array)
 396                           (declare (optimize (speed 3) (safety 0))
 397                                    (type index index end-1))
 398                           (setf (%raw-bits result-bit-array index)
 399                                 (,',wordfun (%raw-bits bit-array-1 index)
 400                                             (%raw-bits bit-array-2 index))))))))))
 401  (def bit-and word-logical-and)
 402  (def bit-ior word-logical-or)
 403  (def bit-xor word-logical-xor)
 404  (def bit-eqv word-logical-eqv)
 405  (def bit-nand word-logical-nand)
 406  (def bit-nor word-logical-nor)
 407  (def bit-andc1 word-logical-andc1)
 408  (def bit-andc2 word-logical-andc2)
 409  (def bit-orc1 word-logical-orc1)
 410  (def bit-orc2 word-logical-orc2))
 411
 412 (deftransform bit-not
 413               ((bit-array result-bit-array)
 414                (simple-bit-vector simple-bit-vector) *
 415                :node node :policy (>= speed space))
 416   `(progn
 417      ,@(unless (policy node (zerop safety))
 418          '((unless (= (length bit-array)
 419                       (length result-bit-array))
 420              (error "Argument and result bit arrays are not the same length:~
 421                      ~%  ~S~%  ~S"
 422                     bit-array result-bit-array))))
 423     (let ((length (length result-bit-array)))
 424       (if (= length 0)
 425           ;; We avoid doing anything to 0-length bit-vectors, or rather,
 426           ;; the memory that follows them. Other divisible-by
 427           ;; n-word-bits cases are handled by the (1- length), below.
 428           ;; CSR, 2002-04-24
 429           result-bit-array
 430           (do ((index sb!vm:vector-data-offset (1+ index))
 431                (end-1 (+ sb!vm:vector-data-offset
 432                          ;; bit-vectors of length 1 to n-word-bits need
 433                          ;; precisely one (SETF %RAW-BITS), done here in
 434                          ;; the epilogue. - CSR, 2002-04-24
 435                          (truncate (truly-the index (1- length))
 436                                    sb!vm:n-word-bits))))
 437               ((>= index end-1)
 438                (setf (%raw-bits result-bit-array index)
 439                      (word-logical-not (%raw-bits bit-array index)))
 440                result-bit-array)
 441             (declare (optimize (speed 3) (safety 0))
 442                      (type index index end-1))
 443             (setf (%raw-bits result-bit-array index)
 444                   (word-logical-not (%raw-bits bit-array index))))))))
 445
 446 (deftransform bit-vector-= ((x y) (simple-bit-vector simple-bit-vector))
 447   `(and (= (length x) (length y))
 448         (let ((length (length x)))
 449           (or (= length 0)
 450               (do* ((i sb!vm:vector-data-offset (+ i 1))
 451                     (end-1 (+ sb!vm:vector-data-offset
 452                               (floor (1- length) sb!vm:n-word-bits))))
 453                    ((>= i end-1)
 454                     (let* ((extra (1+ (mod (1- length) sb!vm:n-word-bits)))
 455                            (mask (ash #.(1- (ash 1 sb!vm:n-word-bits))
 456                                       (- extra sb!vm:n-word-bits)))
 457                            (numx
 458                             (logand
 459                              (ash mask
 460                                   ,(ecase sb!c:*backend-byte-order*
 461                                      (:little-endian 0)
 462                                      (:big-endian
 463                                       '(- sb!vm:n-word-bits extra))))
 464                              (%raw-bits x i)))
 465                            (numy
 466                             (logand
 467                              (ash mask
 468                                   ,(ecase sb!c:*backend-byte-order*
 469                                      (:little-endian 0)
 470                                      (:big-endian
 471                                       '(- sb!vm:n-word-bits extra))))
 472                              (%raw-bits y i))))
 473                       (declare (type (integer 1 #.sb!vm:n-word-bits) extra)
 474                                (type sb!vm:word mask numx numy))
 475                       (= numx numy)))
 476                 (declare (type index i end-1))
 477                 (let ((numx (%raw-bits x i))
 478                       (numy (%raw-bits y i)))
 479                   (declare (type sb!vm:word numx numy))
 480                   (unless (= numx numy)
 481                     (return nil))))))))
 482
 483 (deftransform count ((item sequence) (bit simple-bit-vector) *
 484                      :policy (>= speed space))
 485   `(let ((length (length sequence)))
 486     (if (zerop length)
 487         0
 488         (do ((index sb!vm:vector-data-offset (1+ index))
 489              (count 0)
 490              (end-1 (+ sb!vm:vector-data-offset
 491                        (truncate (truly-the index (1- length))
 492                                  sb!vm:n-word-bits))))
 493             ((>= index end-1)
 494              (let* ((extra (1+ (mod (1- length) sb!vm:n-word-bits)))
 495                     (mask (ash #.(1- (ash 1 sb!vm:n-word-bits))
 496                                (- extra sb!vm:n-word-bits)))
 497                     (bits (logand (ash mask
 498                                        ,(ecase sb!c:*backend-byte-order*
 499                                                (:little-endian 0)
 500                                                (:big-endian
 501                                                 '(- sb!vm:n-word-bits extra))))
 502                                   (%raw-bits sequence index))))
 503                (declare (type (integer 1 #.sb!vm:n-word-bits) extra))
 504                (declare (type sb!vm:word mask bits))
 505                (incf count (logcount bits))
 506                ,(if (constant-lvar-p item)
 507                     (if (zerop (lvar-value item))
 508                         '(- length count)
 509                         'count)
 510                     '(if (zerop item)
 511                          (- length count)
 512                          count))))
 513           (declare (type index index count end-1)
 514                    (optimize (speed 3) (safety 0)))
 515           (incf count (logcount (%raw-bits sequence index)))))))
 516
 517 (deftransform fill ((sequence item) (simple-bit-vector bit) *
 518                     :policy (>= speed space))
 519   (let ((value (if (constant-lvar-p item)
 520                    (if (= (lvar-value item) 0)
 521                        0
 522                        #.(1- (ash 1 sb!vm:n-word-bits)))
 523                    `(if (= item 0) 0 #.(1- (ash 1 sb!vm:n-word-bits))))))
 524     `(let ((length (length sequence))
 525            (value ,value))
 526        (if (= length 0)
 527            sequence
 528            (do ((index sb!vm:vector-data-offset (1+ index))
 529                 (end-1 (+ sb!vm:vector-data-offset
 530                           ;; bit-vectors of length 1 to n-word-bits need
 531                           ;; precisely one (SETF %RAW-BITS), done here
 532                           ;; in the epilogue. - CSR, 2002-04-24
 533                           (truncate (truly-the index (1- length))
 534                                     sb!vm:n-word-bits))))
 535                ((>= index end-1)
 536                 (setf (%raw-bits sequence index) value)
 537                 sequence)
 538              (declare (optimize (speed 3) (safety 0))
 539                       (type index index end-1))
 540              (setf (%raw-bits sequence index) value))))))
 541
 542 (deftransform fill ((sequence item) (simple-base-string base-char) *
 543                     :policy (>= speed space))
 544   (let ((value (if (constant-lvar-p item)
 545                    (let* ((char (lvar-value item))
 546                           (code (sb!xc:char-code char))
 547                           (accum 0))
 548                      (dotimes (i sb!vm:n-word-bytes accum)
 549                        (setf accum (logior accum (ash code (* 8 i))))))
 550                    `(let ((code (sb!xc:char-code item)))
 551                      (logior ,@(loop for i from 0 below sb!vm:n-word-bytes
 552                                      collect `(ash code ,(* 8 i))))))))
 553     `(let ((length (length sequence))
 554            (value ,value))
 555       (multiple-value-bind (times rem)
 556           (truncate length sb!vm:n-word-bytes)
 557         (do ((index sb!vm:vector-data-offset (1+ index))
 558              (end (+ times sb!vm:vector-data-offset)))
 559             ((>= index end)
 560              (let ((place (* times sb!vm:n-word-bytes)))
 561                (declare (fixnum place))
 562                (dotimes (j rem sequence)
 563                  (declare (index j))
 564                  (setf (schar sequence (the index (+ place j))) item))))
 565           (declare (optimize (speed 3) (safety 0))
 566                    (type index index))
 567           (setf (%raw-bits sequence index) value))))))
 568 \f
 569 ;;;; %BYTE-BLT
 570
 571 ;;; FIXME: The old CMU CL code used various COPY-TO/FROM-SYSTEM-AREA
 572 ;;; stuff (with all the associated bit-index cruft and overflow
 573 ;;; issues) even for byte moves. In SBCL, we're converting to byte
 574 ;;; moves as problems are discovered with the old code, and this is
 575 ;;; currently (ca. sbcl-0.6.12.30) the main interface for code in
 576 ;;; SB!KERNEL and SB!SYS (e.g. i/o code). It's not clear that it's the
 577 ;;; ideal interface, though, and it probably deserves some thought.
 578 (deftransform %byte-blt ((src src-start dst dst-start dst-end)
 579                          ((or (simple-unboxed-array (*)) system-area-pointer)
 580                           index
 581                           (or (simple-unboxed-array (*)) system-area-pointer)
 582                           index
 583                           index))
 584   ;; FIXME: CMU CL had a hairier implementation of this (back when it
 585   ;; was still called (%PRIMITIVE BYTE-BLT). It had the small problem
 586   ;; that it didn't work for large (>16M) values of SRC-START or
 587   ;; DST-START. However, it might have been more efficient. In
 588   ;; particular, I don't really know how much the foreign function
 589   ;; call costs us here. My guess is that if the overhead is
 590   ;; acceptable for SQRT and COS, it's acceptable here, but this
 591   ;; should probably be checked. -- WHN
 592   '(flet ((sapify (thing)
 593             (etypecase thing
 594               (system-area-pointer thing)
 595               ;; FIXME: The code here rather relies on the simple
 596               ;; unboxed array here having byte-sized entries. That
 597               ;; should be asserted explicitly, I just haven't found
 598               ;; a concise way of doing it. (It would be nice to
 599               ;; declare it in the DEFKNOWN too.)
 600               ((simple-unboxed-array (*)) (vector-sap thing)))))
 601      (declare (inline sapify))
 602     (with-pinned-objects (dst src)
 603       (memmove (sap+ (sapify dst) dst-start)
 604                (sap+ (sapify src) src-start)
 605                (- dst-end dst-start)))
 606      (values)))
 607 \f
 608 ;;;; transforms for EQL of floating point values
 609
 610 (deftransform eql ((x y) (single-float single-float))
 611   '(= (single-float-bits x) (single-float-bits y)))
 612
 613 (deftransform eql ((x y) (double-float double-float))
 614   '(and (= (double-float-low-bits x) (double-float-low-bits y))
 615         (= (double-float-high-bits x) (double-float-high-bits y))))
 616
 617 \f
 618 ;;;; modular functions
 619 (define-good-modular-fun logand :unsigned)
 620 (define-good-modular-fun logior :unsigned)
 621 ;;; FIXME: XOR? ANDC1, ANDC2?  -- CSR, 2003-09-16
 622
 623 (macrolet
 624     ((def (name class width)
 625        (let ((type (ecase class
 626                      (:unsigned 'unsigned-byte)
 627                      (:signed 'signed-byte))))
 628          `(progn
 629             (defknown ,name (integer (integer 0)) (,type ,width)
 630                       (foldable flushable movable))
 631             (define-modular-fun-optimizer ash ((integer count) ,class :width width)
 632               (when (and (<= width ,width)
 633                          (or (and (constant-lvar-p count)
 634                                   (plusp (lvar-value count)))
 635                              (csubtypep (lvar-type count)
 636                                         (specifier-type '(and unsigned-byte fixnum)))))
 637                 (cut-to-width integer ,class width)
 638                 ',name))
 639             (setf (gethash ',name (modular-class-versions (find-modular-class ',class)))
 640                   `(ash ,',width))))))
 641   ;; This should really be dependent on SB!VM:N-WORD-BITS, but since we
 642   ;; don't have a true Alpha64 port yet, we'll have to stick to
 643   ;; SB!VM:N-MACHINE-WORD-BITS for the time being.  --njf, 2004-08-14
 644   #!+#.(cl:if (cl:= 32 sb!vm:n-machine-word-bits) '(and) '(or))
 645   (progn
 646     #!+x86 (def sb!vm::ash-left-smod30 :signed 30)
 647     (def sb!vm::ash-left-mod32 :unsigned 32))
 648   #!+#.(cl:if (cl:= 64 sb!vm:n-machine-word-bits) '(and) '(or))
 649   (progn
 650     #!+x86-64 (def sb!vm::ash-left-smod61 :signed 61)
 651     (def sb!vm::ash-left-mod64 :unsigned 64)))
 652
 653 \f
 654 ;;;; word-wise logical operations
 655
 656 ;;; These transforms assume the presence of modular arithmetic to
 657 ;;; generate efficient code.
 658
 659 (define-source-transform word-logical-not (x)
 660   `(logand (lognot (the sb!vm:word ,x)) #.(1- (ash 1 sb!vm:n-word-bits))))
 661
 662 (deftransform word-logical-and ((x y))
 663   '(logand x y))
 664
 665 (deftransform word-logical-nand ((x y))
 666   '(logand (lognand x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 667
 668 (deftransform word-logical-or ((x y))
 669   '(logior x y))
 670
 671 (deftransform word-logical-nor ((x y))
 672   '(logand (lognor x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 673
 674 (deftransform word-logical-xor ((x y))
 675   '(logxor x y))
 676
 677 (deftransform word-logical-eqv ((x y))
 678   '(logand (logeqv x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 679
 680 (deftransform word-logical-orc1 ((x y))
 681   '(logand (logorc1 x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 682
 683 (deftransform word-logical-orc2 ((x y))
 684   '(logand (logorc2 x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 685
 686 (deftransform word-logical-andc1 ((x y))
 687   '(logand (logandc1 x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 688
 689 (deftransform word-logical-andc2 ((x y))
 690   '(logand (logandc2 x y) #.(1- (ash 1 sb!vm:n-word-bits))))
 691
 692 \f
 693 ;;; There are two different ways the multiplier can be recoded. The
 694 ;;; more obvious is to shift X by the correct amount for each bit set
 695 ;;; in Y and to sum the results. But if there is a string of bits that
 696 ;;; are all set, you can add X shifted by one more then the bit
 697 ;;; position of the first set bit and subtract X shifted by the bit
 698 ;;; position of the last set bit. We can't use this second method when
 699 ;;; the high order bit is bit 31 because shifting by 32 doesn't work
 700 ;;; too well.
 701 (defun ub32-strength-reduce-constant-multiply (arg num)
 702   (declare (type (unsigned-byte 32) num))
 703   (let ((adds 0) (shifts 0)
 704         (result nil) first-one)
 705     (labels ((add (next-factor)
 706                (setf result
 707                      (if result
 708                          (progn (incf adds) `(+ ,result ,next-factor))
 709                          next-factor))))
 710       (declare (inline add))
 711       (dotimes (bitpos 32)
 712         (if first-one
 713             (when (not (logbitp bitpos num))
 714               (add (if (= (1+ first-one) bitpos)
 715                        ;; There is only a single bit in the string.
 716                        (progn (incf shifts) `(ash ,arg ,first-one))
 717                        ;; There are at least two.
 718                        (progn
 719                          (incf adds)
 720                          (incf shifts 2)
 721                          `(- (ash ,arg ,bitpos)
 722                              (ash ,arg ,first-one)))))
 723               (setf first-one nil))
 724             (when (logbitp bitpos num)
 725               (setf first-one bitpos))))
 726       (when first-one
 727         (cond ((= first-one 31))
 728               ((= first-one 30) (incf shifts) (add `(ash ,arg 30)))
 729               (t
 730                (incf shifts 2)
 731                (incf adds)
 732                (add `(- (ash ,arg 31)
 733                         (ash ,arg ,first-one)))))
 734         (incf shifts)
 735         (add `(ash ,arg 31))))
 736     (values (if (plusp adds)
 737                 `(logand ,result #.(1- (ash 1 32))) ; using modular arithmetic
 738                 result)
 739             adds
 740             shifts)))
 741
 742 \f
 743 ;;; Transform GET-LISP-OBJ-ADDRESS for constant immediates, since the normal
 744 ;;; VOP can't handle them.
 745
 746 (deftransform sb!vm::get-lisp-obj-address ((obj) ((constant-arg fixnum)))
 747   (ash (lvar-value obj) sb!vm::n-fixnum-tag-bits))
 748
 749 (deftransform sb!vm::get-lisp-obj-address ((obj) ((constant-arg character)))
 750   (logior sb!vm::character-widetag
 751           (ash (char-code (lvar-value obj)) sb!vm::n-widetag-bits)))