src/pcl/dlisp.lisp

   1 ;;;; This software is part of the SBCL system. See the README file for
   2 ;;;; more information.
   3
   4 ;;;; This software is derived from software originally released by Xerox
   5 ;;;; Corporation. Copyright and release statements follow. Later modifications
   6 ;;;; to the software are in the public domain and are provided with
   7 ;;;; absolutely no warranty. See the COPYING and CREDITS files for more
   8 ;;;; information.
   9
  10 ;;;; copyright information from original PCL sources:
  11 ;;;;
  12 ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
  13 ;;;; All rights reserved.
  14 ;;;;
  15 ;;;; Use and copying of this software and preparation of derivative works based
  16 ;;;; upon this software are permitted. Any distribution of this software or
  17 ;;;; derivative works must comply with all applicable United States export
  18 ;;;; control laws.
  19 ;;;;
  20 ;;;; This software is made available AS IS, and Xerox Corporation makes no
  21 ;;;; warranty about the software, its performance or its conformity to any
  22 ;;;; specification.
  23
  24 (in-package "SB-PCL")
  25
  26
  27 ;;;; some support stuff for getting a hold of symbols that we need when
  28 ;;;; building the discriminator codes. It's OK for these to be interned
  29 ;;;; symbols because we don't capture any user code in the scope in which
  30 ;;;; these symbols are bound.
  31
  32 (declaim (list *dfun-arg-symbols*))
  33 (defvar *dfun-arg-symbols* '(.ARG0. .ARG1. .ARG2. .ARG3.))
  34
  35 (defun dfun-arg-symbol (arg-number)
  36   (or (nth arg-number *dfun-arg-symbols*)
  37       (format-symbol *pcl-package* ".ARG~A." arg-number)))
  38
  39 (declaim (list *slot-vector-symbols*))
  40 (defvar *slot-vector-symbols* '(.SLOTS0. .SLOTS1. .SLOTS2. .SLOTS3.))
  41
  42 (defun slot-vector-symbol (arg-number)
  43   (or (nth arg-number *slot-vector-symbols*)
  44       (format-symbol *pcl-package* ".SLOTS~A." arg-number)))
  45
  46 (declaim (inline make-dfun-required-args))
  47 (defun make-dfun-required-args (count)
  48   (declare (type index count))
  49   (let (result)
  50     (dotimes (i count (nreverse result))
  51       (push (dfun-arg-symbol i) result))))
  52
  53 (defun make-dfun-lambda-list (nargs applyp)
  54   (let ((required (make-dfun-required-args nargs)))
  55     (if applyp
  56         (nconc required
  57                ;; Use &MORE arguments to avoid consing up an &REST list
  58                ;; that we might not need at all. See MAKE-EMF-CALL and
  59                ;; INVOKE-EFFECTIVE-METHOD-FUNCTION for the other
  60                ;; pieces.
  61                '(&more .dfun-more-context. .dfun-more-count.))
  62         required)))
  63
  64 (defun make-dlap-lambda-list (nargs applyp)
  65   (let ((required (make-dfun-required-args nargs)))
  66     ;; Return the full lambda list, the required arguments, a form
  67     ;; that will generate a rest-list, and a list of the &MORE
  68     ;; parameters used.
  69     ;; Beware of deep voodoo! The DEFKNOWN for %LISTIFY-REST-ARGS says that its
  70     ;; second argument is INDEX, but the THE form below is "weaker" on account
  71     ;; of the vop operand restrictions or something that I don't understand.
  72     ;; Which is to say, PCL compilation reliably broke when changed to INDEX.
  73     (if applyp
  74         (values (append required '(&more .more-context. .more-count.))
  75                 required
  76                 '((sb-c:%listify-rest-args
  77                    .more-context. (the (and unsigned-byte fixnum)
  78                                     .more-count.)))
  79                 '(.more-context. .more-count.))
  80         (values required required nil nil))))
  81
  82 (defun make-emf-call (nargs applyp fn-variable &optional emf-type)
  83   (let ((required (make-dfun-required-args nargs)))
  84     `(,(if (eq emf-type 'fast-method-call)
  85            'invoke-effective-method-function-fast
  86            'invoke-effective-method-function)
  87        ,fn-variable
  88        ,applyp
  89        :required-args ,required
  90        ;; INVOKE-EFFECTIVE-METHOD-FUNCTION will decide whether to use
  91        ;; the :REST-ARG version or the :MORE-ARG version depending on
  92        ;; the type of the EMF.
  93        :rest-arg ,(if applyp
  94                       ;; Creates a list from the &MORE arguments.
  95                       '((sb-c:%listify-rest-args ; See above re. voodoo
  96                          .dfun-more-context.
  97                          (the (and unsigned-byte fixnum)
  98                            .dfun-more-count.)))
  99                       nil)
 100        :more-arg ,(when applyp
 101                     '(.dfun-more-context. .dfun-more-count.)))))
 102
 103 (defun make-fast-method-call-lambda-list (nargs applyp)
 104   (list* '.pv. '.next-method-call. (make-dfun-lambda-list nargs applyp)))
 105 \f
 106 ;;; Emitting various accessors.
 107
 108 (defun emit-one-class-reader (class-slot-p)
 109   (emit-reader/writer :reader 1 class-slot-p))
 110
 111 (defun emit-one-class-boundp (class-slot-p)
 112   (emit-reader/writer :boundp 1 class-slot-p))
 113
 114 (defun emit-one-class-writer (class-slot-p)
 115   (emit-reader/writer :writer 1 class-slot-p))
 116
 117 (defun emit-two-class-reader (class-slot-p)
 118   (emit-reader/writer :reader 2 class-slot-p))
 119
 120 (defun emit-two-class-boundp (class-slot-p)
 121   (emit-reader/writer :boundp 2 class-slot-p))
 122
 123 (defun emit-two-class-writer (class-slot-p)
 124   (emit-reader/writer :writer 2 class-slot-p))
 125
 126 ;;; --------------------------------
 127
 128 (defun emit-one-index-readers (class-slot-p)
 129   (emit-one-or-n-index-reader/writer :reader nil class-slot-p))
 130
 131 (defun emit-one-index-boundps (class-slot-p)
 132   (emit-one-or-n-index-reader/writer :boundp nil class-slot-p))
 133
 134 (defun emit-one-index-writers (class-slot-p)
 135   (emit-one-or-n-index-reader/writer :writer nil class-slot-p))
 136
 137 (defun emit-n-n-readers ()
 138   (emit-one-or-n-index-reader/writer :reader t nil))
 139
 140 (defun emit-n-n-boundps ()
 141   (emit-one-or-n-index-reader/writer :boundp t nil))
 142
 143 (defun emit-n-n-writers ()
 144   (emit-one-or-n-index-reader/writer :writer t nil))
 145
 146 ;;; --------------------------------
 147
 148 (defun emit-checking (metatypes applyp)
 149   (emit-checking-or-caching nil nil metatypes applyp))
 150
 151 (defun emit-caching (metatypes applyp)
 152   (emit-checking-or-caching t nil metatypes applyp))
 153
 154 (defun emit-in-checking-cache-p (metatypes)
 155   (emit-checking-or-caching nil t metatypes nil))
 156
 157 (defun emit-constant-value (metatypes)
 158   (emit-checking-or-caching t t metatypes nil))
 159
 160 ;;; --------------------------------
 161
 162 ;;; FIXME: What do these variables mean?
 163 (defvar *precompiling-lap* nil)
 164
 165 (defun emit-default-only (metatypes applyp)
 166   (multiple-value-bind (lambda-list args rest-arg more-arg)
 167       (make-dlap-lambda-list (length metatypes) applyp)
 168     (generating-lisp '(emf)
 169                      lambda-list
 170                      `(invoke-effective-method-function emf
 171                                                         ,applyp
 172                                                         :required-args ,args
 173                                                         :more-arg ,more-arg
 174                                                         :rest-arg ,rest-arg))))
 175
 176 ;;; --------------------------------
 177
 178 (defun generating-lisp (closure-variables args form)
 179   (let ((lambda `(lambda ,closure-variables
 180                    ,@(when (member 'miss-fn closure-variables)
 181                            `((declare (type function miss-fn))))
 182                    #'(lambda ,args
 183                        (let ()
 184                          (declare #.*optimize-speed*)
 185                          ,form)))))
 186     (values (if *precompiling-lap*
 187                 `#',lambda
 188                 (compile nil lambda))
 189             nil)))
 190
 191 ;;; note on implementation for CMU 17 and later (including SBCL):
 192 ;;; Since STD-INSTANCE-P is weakened, that branch may run on non-PCL
 193 ;;; instances (structures). The result will be the non-wrapper layout
 194 ;;; for the structure, which will cause a miss. The "slots" will be
 195 ;;; whatever the first slot is, but will be ignored. Similarly,
 196 ;;; FSC-INSTANCE-P returns true on funcallable structures as well as
 197 ;;; PCL fins.
 198 (defun emit-reader/writer (reader/writer 1-or-2-class class-slot-p)
 199   (let ((instance nil)
 200         (arglist  ())
 201         (closure-variables ())
 202         (read-form (emit-slot-read-form class-slot-p 'index 'slots)))
 203     (ecase reader/writer
 204       ((:reader :boundp)
 205        (setq instance (dfun-arg-symbol 0)
 206              arglist  (list instance)))
 207       (:writer (setq instance (dfun-arg-symbol 1)
 208                      arglist  (list (dfun-arg-symbol 0) instance))))
 209     (ecase 1-or-2-class
 210       (1 (setq closure-variables '(wrapper-0 index miss-fn)))
 211       (2 (setq closure-variables '(wrapper-0 wrapper-1 index miss-fn))))
 212     (generating-lisp
 213      closure-variables
 214      arglist
 215      `(let* (,@(unless class-slot-p `((slots nil)))
 216                (wrapper (cond ((std-instance-p ,instance)
 217                                ,@(unless class-slot-p
 218                                    `((setq slots
 219                                            (std-instance-slots ,instance))))
 220                                (std-instance-wrapper ,instance))
 221                               ((fsc-instance-p ,instance)
 222                                ,@(unless class-slot-p
 223                                    `((setq slots
 224                                            (fsc-instance-slots ,instance))))
 225                                (fsc-instance-wrapper ,instance)))))
 226         (block access
 227           (when (and wrapper
 228                      (not (zerop (layout-clos-hash wrapper)))
 229                      ,@(if (eql 1 1-or-2-class)
 230                            `((eq wrapper wrapper-0))
 231                            `((or (eq wrapper wrapper-0)
 232                                  (eq wrapper wrapper-1)))))
 233             ,@(ecase reader/writer
 234                 (:reader
 235                  `((let ((value ,read-form))
 236                      (unless (eq value +slot-unbound+)
 237                        (return-from access value)))))
 238                 (:boundp
 239                  `((let ((value ,read-form))
 240                      (return-from access (not (eq value +slot-unbound+))))))
 241                 (:writer
 242                  `((return-from access (setf ,read-form ,(car arglist)))))))
 243           (funcall miss-fn ,@arglist))))))
 244
 245 (defun emit-slot-read-form (class-slot-p index slots)
 246   (if class-slot-p
 247       `(cdr ,index)
 248       `(clos-slots-ref ,slots ,index)))
 249
 250 (defun emit-boundp-check (value-form miss-fn arglist)
 251   `(let ((value ,value-form))
 252      (if (eq value +slot-unbound+)
 253          (funcall ,miss-fn ,@arglist)
 254          value)))
 255
 256 (defun emit-slot-access (reader/writer class-slot-p slots
 257                          index miss-fn arglist)
 258   (let ((read-form (emit-slot-read-form class-slot-p index slots)))
 259     (ecase reader/writer
 260       (:reader (emit-boundp-check read-form miss-fn arglist))
 261       (:boundp `(not (eq ,read-form +slot-unbound+)))
 262       (:writer `(setf ,read-form ,(car arglist))))))
 263
 264 (defmacro emit-reader/writer-macro (reader/writer 1-or-2-class class-slot-p)
 265   (let ((*precompiling-lap* t))
 266     (values
 267      (emit-reader/writer reader/writer 1-or-2-class class-slot-p))))
 268
 269 ;; If CACHED-INDEX-P is false, then the slot location is a constant and
 270 ;; the cache holds layouts eligible to use that index.
 271 ;; If true, then the cache is a map of layout -> index.
 272 (defun emit-one-or-n-index-reader/writer (reader/writer
 273                                           cached-index-p
 274                                           class-slot-p)
 275   (multiple-value-bind (arglist metatypes)
 276       (ecase reader/writer
 277         ((:reader :boundp)
 278          (values (list (dfun-arg-symbol 0))
 279                  '(standard-instance)))
 280         (:writer (values (list (dfun-arg-symbol 0) (dfun-arg-symbol 1))
 281                          '(t standard-instance))))
 282     (generating-lisp
 283      `(cache ,@(unless cached-index-p '(index)) miss-fn)
 284      arglist
 285      `(let (,@(unless class-slot-p '(slots))
 286             ,@(when cached-index-p '(index)))
 287         ,(emit-dlap 'cache arglist metatypes
 288                     (emit-slot-access reader/writer class-slot-p
 289                                       'slots 'index 'miss-fn arglist)
 290                     `(funcall miss-fn ,@arglist)
 291                     (when cached-index-p 'index)
 292                     (unless class-slot-p '(slots)))))))
 293
 294 (defmacro emit-one-or-n-index-reader/writer-macro
 295     (reader/writer cached-index-p class-slot-p)
 296   (let ((*precompiling-lap* t))
 297     (values
 298      (emit-one-or-n-index-reader/writer reader/writer
 299                                         cached-index-p
 300                                         class-slot-p))))
 301
 302 (defun emit-miss (miss-fn args applyp)
 303   (if applyp
 304       `(multiple-value-call ,miss-fn ,@args
 305                             (sb-c::%more-arg-values .more-context.
 306                                                     0
 307                                                     .more-count.))
 308       `(funcall ,miss-fn ,@args)))
 309
 310 ;; (cache-emf, return-value):
 311 ;;  NIL / NIL : GF has a single EMF. Invoke it when layouts are in cache.
 312 ;;  NIL / T   : GF has a single EMF. Return T when layouts are in cache.
 313 ;;  T   / NIL : Look for the EMF for argument layouts. Invoke it when in cache.
 314 ;;  T   / T   : Look for the EMF for argument layouts. Return it when in cache.
 315 ;;
 316 ;;  METATYPES must be acceptable to EMIT-FETCH-WRAPPER.
 317 ;;  APPLYP says whether there is a &MORE context.
 318 (defun emit-checking-or-caching (cached-emf-p return-value-p metatypes applyp)
 319   (multiple-value-bind (lambda-list args rest-arg more-arg)
 320       (make-dlap-lambda-list (length metatypes) applyp)
 321     (generating-lisp
 322      `(cache ,@(unless cached-emf-p '(emf)) miss-fn)
 323      lambda-list
 324      `(let (,@(when cached-emf-p '(emf)))
 325         ,(emit-dlap 'cache args metatypes
 326                     (if return-value-p
 327                         (if cached-emf-p 'emf t)
 328                         `(invoke-effective-method-function
 329                           emf ,applyp
 330                           :required-args ,args
 331                           :more-arg ,more-arg
 332                           :rest-arg ,rest-arg))
 333                     (emit-miss 'miss-fn args applyp)
 334                     (when cached-emf-p 'emf))))))
 335
 336 (defmacro emit-checking-or-caching-macro (cached-emf-p
 337                                           return-value-p
 338                                           metatypes
 339                                           applyp)
 340   (let ((*precompiling-lap* t))
 341     (values
 342      (emit-checking-or-caching cached-emf-p return-value-p metatypes applyp))))
 343
 344 (defun emit-dlap (cache-var args metatypes hit-form miss-form value-var
 345                   &optional slot-vars)
 346   (let* ((index -1)
 347          (miss-tag (gensym "MISSED"))
 348          (wrapper-bindings (mapcan (lambda (arg mt)
 349                                      (unless (eq mt t)
 350                                        (incf index)
 351                                        `((,(format-symbol *pcl-package*
 352                                                           "WRAPPER-~D"
 353                                                           index)
 354                                           ,(emit-fetch-wrapper
 355                                             mt arg miss-tag (pop slot-vars))))))
 356                                    args metatypes))
 357          (wrapper-vars (mapcar #'car wrapper-bindings)))
 358     (declare (fixnum index))
 359     (unless wrapper-vars
 360       (error "Every metatype is T."))
 361     `(prog ()
 362         (return
 363           (let ,wrapper-bindings
 364             ,(emit-cache-lookup cache-var wrapper-vars miss-tag value-var)
 365             ,hit-form))
 366       ,miss-tag
 367         (return ,miss-form))))
 368
 369 ;; SLOTS-VAR, if supplied, is the variable to update with instance-slots
 370 ;; by side-effect of fetching the wrapper for ARGUMENT.
 371 (defun emit-fetch-wrapper (metatype argument miss-tag &optional slots-var)
 372   (ecase metatype
 373     ((standard-instance)
 374      ;; This branch may run on non-pcl instances (structures). The
 375      ;; result will be the non-wrapper layout for the structure, which
 376      ;; will cause a miss. Since refencing the structure is rather iffy
 377      ;; if it should have no slots, or only raw slots, we use FOR-STD-CLASS-P
 378      ;; to ensure that we have a wrapper.
 379      ;;
 380      ;; FIXME: If we unify layouts and wrappers we can use
 381      ;; instance-slots-layout instead of for-std-class-p, as if there
 382      ;; are no layouts there are no slots to worry about.
 383      (with-unique-names (wrapper)
 384        `(cond ((std-instance-p ,argument)
 385                ,(if slots-var
 386                     `(let ((,wrapper (std-instance-wrapper ,argument)))
 387                        (when (layout-for-std-class-p ,wrapper)
 388                          (setq ,slots-var (std-instance-slots ,argument)))
 389                        ,wrapper)
 390                     `(std-instance-wrapper ,argument)))
 391               ((fsc-instance-p ,argument)
 392                ,(if slots-var
 393                     `(let ((,wrapper (fsc-instance-wrapper ,argument)))
 394                        (when (layout-for-std-class-p ,wrapper)
 395                          (setq ,slots-var (fsc-instance-slots ,argument)))
 396                        ,wrapper)
 397                     `(fsc-instance-wrapper ,argument)))
 398                (t (go ,miss-tag)))))
 399     ;; Sep92 PCL used to distinguish between some of these cases (and
 400     ;; spuriously exclude others).  Since in SBCL
 401     ;; WRAPPER-OF/LAYOUT-OF/BUILT-IN-OR-STRUCTURE-WRAPPER are all
 402     ;; equivalent and inlined to each other, we can collapse some
 403     ;; spurious differences.
 404     ((class system-instance structure-instance condition-instance)
 405      (when slots-var
 406        (bug "SLOT requested for metatype ~S, but it isn't going to happen."
 407             metatype))
 408      `(layout-of ,argument))
 409     ;; a metatype of NIL should never be seen here, as NIL is only in
 410     ;; the metatypes before a generic function is fully initialized.
 411     ;; T should never be seen because we never need to get a wrapper
 412     ;; to do dispatch if all methods have T as the respective
 413     ;; specializer.
 414     ((t nil)
 415      (bug "~@<metatype ~S seen in ~S.~@:>" metatype 'emit-fetch-wrapper))))