src/pcl/low.lisp

   1 ;;;; This file contains portable versions of low-level functions and macros
   2 ;;;; which are ripe for implementation specific customization. None of the code
   3 ;;;; in this file *has* to be customized for a particular Common Lisp
   4 ;;;; implementation. Moreover, in some implementations it may not make any
   5 ;;;; sense to customize some of this code.
   6 ;;;;
   7 ;;;; The original version was intended to support portable customization to
   8 ;;;; lotso different Lisp implementations. This functionality is gone in the
   9 ;;;; current version, and it now runs only under SBCL. (Now that ANSI Common
  10 ;;;; Lisp has mixed CLOS into the insides of the system (e.g. error handling
  11 ;;;; and printing) so deeply that it's not very meaningful to bootstrap Common
  12 ;;;; Lisp without CLOS, the old functionality is of dubious use. -- WHN
  13 ;;;; 19981108)
  14
  15 ;;;; This software is part of the SBCL system. See the README file for more
  16 ;;;; information.
  17
  18 ;;;; This software is derived from software originally released by Xerox
  19 ;;;; Corporation. Copyright and release statements follow. Later modifications
  20 ;;;; to the software are in the public domain and are provided with
  21 ;;;; absolutely no warranty. See the COPYING and CREDITS files for more
  22 ;;;; information.
  23
  24 ;;;; copyright information from original PCL sources:
  25 ;;;;
  26 ;;;; Copyright (c) 1985, 1986, 1987, 1988, 1989, 1990 Xerox Corporation.
  27 ;;;; All rights reserved.
  28 ;;;;
  29 ;;;; Use and copying of this software and preparation of derivative works based
  30 ;;;; upon this software are permitted. Any distribution of this software or
  31 ;;;; derivative works must comply with all applicable United States export
  32 ;;;; control laws.
  33 ;;;;
  34 ;;;; This software is made available AS IS, and Xerox Corporation makes no
  35 ;;;; warranty about the software, its performance or its conformity to any
  36 ;;;; specification.
  37
  38 (in-package "SB-PCL")
  39 \f
  40 (eval-when (:compile-toplevel :load-toplevel :execute)
  41 (defvar *optimize-speed*
  42   '(optimize (speed 3) (safety 0)))
  43 ) ; EVAL-WHEN
  44
  45 (defmacro dotimes-fixnum ((var count &optional (result nil)) &body body)
  46   `(dotimes (,var (the fixnum ,count) ,result)
  47      (declare (fixnum ,var))
  48      ,@body))
  49 \f
  50 ;;;; early definition of WRAPPER
  51 ;;;;
  52 ;;;; Most WRAPPER stuff is defined later, but the DEFSTRUCT itself
  53 ;;;; is here early so that things like (TYPEP .. 'WRAPPER) can be
  54 ;;;; compiled efficiently.
  55
  56 ;;; Note that for SBCL, as for CMU CL, the WRAPPER of a built-in or
  57 ;;; structure class will be some other kind of SB-KERNEL:LAYOUT, but
  58 ;;; this shouldn't matter, since the only two slots that WRAPPER adds
  59 ;;; are meaningless in those cases.
  60 (defstruct (wrapper
  61             (:include layout
  62                       ;; KLUDGE: In CMU CL, the initialization default
  63                       ;; for LAYOUT-INVALID was NIL. In SBCL, that has
  64                       ;; changed to :UNINITIALIZED, but PCL code might
  65                       ;; still expect NIL for the initialization
  66                       ;; default of WRAPPER-INVALID. Instead of trying
  67                       ;; to find out, I just overrode the LAYOUT
  68                       ;; default here. -- WHN 19991204
  69                       (invalid nil))
  70             (:conc-name %wrapper-)
  71             (:constructor make-wrapper-internal)
  72             (:copier nil))
  73   (instance-slots-layout nil :type list)
  74   (class-slots nil :type list))
  75 #-sb-fluid (declaim (sb-ext:freeze-type wrapper))
  76 \f
  77 ;;;; PCL's view of funcallable instances
  78
  79 (!defstruct-with-alternate-metaclass pcl-funcallable-instance
  80   ;; KLUDGE: Note that neither of these slots is ever accessed by its
  81   ;; accessor name as of sbcl-0.pre7.63. Presumably everything works
  82   ;; by puns based on absolute locations. Fun fun fun.. -- WHN 2001-10-30
  83   :slot-names (clos-slots name hash-code)
  84   :boa-constructor %make-pcl-funcallable-instance
  85   :superclass-name funcallable-instance
  86   :metaclass-name random-pcl-classoid
  87   :metaclass-constructor make-random-pcl-classoid
  88   :dd-type funcallable-structure
  89   ;; Only internal implementation code will access these, and these
  90   ;; accesses (slot readers in particular) could easily be a
  91   ;; bottleneck, so it seems reasonable to suppress runtime type
  92   ;; checks.
  93   ;;
  94   ;; (Except note KLUDGE above that these accessors aren't used at all
  95   ;; (!) as of sbcl-0.pre7.63, so for now it's academic.)
  96   :runtime-type-checks-p nil)
  97
  98 (import 'sb-kernel:funcallable-instance-p)
  99
 100 (defun set-funcallable-instance-function (fin new-value)
 101   (declare (type function new-value))
 102   (aver (funcallable-instance-p fin))
 103   (setf (funcallable-instance-fun fin) new-value))
 104 (defmacro fsc-instance-p (fin)
 105   `(funcallable-instance-p ,fin))
 106 (defmacro fsc-instance-wrapper (fin)
 107   `(%funcallable-instance-layout ,fin))
 108 ;;; FIXME: This seems to bear no relation at all to the CLOS-SLOTS
 109 ;;; slot in the FUNCALLABLE-INSTANCE structure, above, which
 110 ;;; (bizarrely) seems to be set to the NAME of the
 111 ;;; FUNCALLABLE-INSTANCE. At least, the index 1 seems to return the
 112 ;;; NAME, and the index 2 NIL.  Weird.  -- CSR, 2002-11-07
 113 (defmacro fsc-instance-slots (fin)
 114   `(%funcallable-instance-info ,fin 0))
 115 (defmacro fsc-instance-hash (fin)
 116   `(%funcallable-instance-info ,fin 3))
 117 \f
 118 (declaim (inline clos-slots-ref (setf clos-slots-ref)))
 119 (declaim (ftype (function (simple-vector index) t) clos-slots-ref))
 120 (defun clos-slots-ref (slots index)
 121   (svref slots index))
 122 (declaim (ftype (function (t simple-vector index) t) (setf clos-slots-ref)))
 123 (defun (setf clos-slots-ref) (new-value slots index)
 124   (setf (svref slots index) new-value))
 125
 126 ;;; Note on implementation under CMU CL >=17 and SBCL: STD-INSTANCE-P
 127 ;;; is only used to discriminate between functions (including FINs)
 128 ;;; and normal instances, so we can return true on structures also. A
 129 ;;; few uses of (OR STD-INSTANCE-P FSC-INSTANCE-P) are changed to
 130 ;;; PCL-INSTANCE-P.
 131 (defmacro std-instance-p (x)
 132   `(%instancep ,x))
 133
 134 ;; a temporary definition used for debugging the bootstrap
 135 #+sb-show
 136 (defun print-std-instance (instance stream depth)
 137   (declare (ignore depth))
 138   (print-unreadable-object (instance stream :type t :identity t)
 139     (let ((class (class-of instance)))
 140       (when (or (eq class (find-class 'standard-class nil))
 141                 (eq class (find-class 'funcallable-standard-class nil))
 142                 (eq class (find-class 'built-in-class nil)))
 143         (princ (early-class-name instance) stream)))))
 144
 145 ;;; This is the value that we stick into a slot to tell us that it is
 146 ;;; unbound. It may seem gross, but for performance reasons, we make
 147 ;;; this an interned symbol. That means that the fast check to see
 148 ;;; whether a slot is unbound is to say (EQ <val> '..SLOT-UNBOUND..).
 149 ;;; That is considerably faster than looking at the value of a special
 150 ;;; variable. Be careful, there are places in the code which actually
 151 ;;; use ..SLOT-UNBOUND.. rather than this variable. So much for
 152 ;;; modularity..
 153 ;;;
 154 ;;; FIXME: Now that we're tightly integrated into SBCL, we could use
 155 ;;; the SBCL built-in unbound value token instead. Perhaps if we did
 156 ;;; so it would be a good idea to define collections of CLOS slots as
 157 ;;; a new type of heap object, instead of using bare SIMPLE-VECTOR, in
 158 ;;; order to avoid problems (in the debugger if nowhere else) with
 159 ;;; SIMPLE-VECTORs some of whose elements are unbound tokens.
 160 (defconstant +slot-unbound+ '..slot-unbound..)
 161
 162 (defmacro %allocate-static-slot-storage--class (no-of-slots)
 163   `(make-array ,no-of-slots :initial-element +slot-unbound+))
 164
 165 (defmacro std-instance-class (instance)
 166   `(wrapper-class* (std-instance-wrapper ,instance)))
 167 \f
 168 ;;; When given a function should give this function the name
 169 ;;; NEW-NAME. Note that NEW-NAME is sometimes a list. Some lisps
 170 ;;; get the upset in the tummy when they start thinking about
 171 ;;; functions which have lists as names. To deal with that there is
 172 ;;; SET-FUN-NAME-INTERN which takes a list spec for a function
 173 ;;; name and turns it into a symbol if need be.
 174 ;;;
 175 ;;; When given a funcallable instance, SET-FUN-NAME *must* side-effect
 176 ;;; that FIN to give it the name. When given any other kind of
 177 ;;; function SET-FUN-NAME is allowed to return a new function which is
 178 ;;; "the same" except that it has the name.
 179 ;;;
 180 ;;; In all cases, SET-FUN-NAME must return the new (or same)
 181 ;;; function. (Unlike other functions to set stuff, it does not return
 182 ;;; the new value.)
 183 (defun set-fun-name (fcn new-name)
 184   #+sb-doc
 185   "Set the name of a compiled function object. Return the function."
 186   (declare (special *boot-state* *the-class-standard-generic-function*))
 187   (cond ((symbolp fcn)
 188          (set-fun-name (symbol-function fcn) new-name))
 189         ((funcallable-instance-p fcn)
 190          (if (if (eq *boot-state* 'complete)
 191                  (typep fcn 'generic-function)
 192                  (eq (class-of fcn) *the-class-standard-generic-function*))
 193              (setf (%funcallable-instance-info fcn 1) new-name)
 194              (bug "unanticipated function type"))
 195          fcn)
 196         (t
 197          ;; pw-- This seems wrong and causes trouble. Tests show
 198          ;; that loading CL-HTTP resulted in ~5400 closures being
 199          ;; passed through this code of which ~4000 of them pointed
 200          ;; to but 16 closure-functions, including 1015 each of
 201          ;; DEFUN MAKE-OPTIMIZED-STD-WRITER-METHOD-FUNCTION
 202          ;; DEFUN MAKE-OPTIMIZED-STD-READER-METHOD-FUNCTION
 203          ;; DEFUN MAKE-OPTIMIZED-STD-BOUNDP-METHOD-FUNCTION.
 204          ;; Since the actual functions have been moved by PURIFY
 205          ;; to memory not seen by GC, changing a pointer there
 206          ;; not only clobbers the last change but leaves a dangling
 207          ;; pointer invalid  after the next GC. Comments in low.lisp
 208          ;; indicate this code need do nothing. Setting the
 209          ;; function-name to NIL loses some info, and not changing
 210          ;; it loses some info of potential hacking value. So,
 211          ;; lets not do this...
 212          #+nil
 213          (let ((header (%closure-fun fcn)))
 214            (setf (%simple-fun-name header) new-name))
 215
 216          ;; XXX Maybe add better scheme here someday.
 217          fcn)))
 218
 219 (defun intern-fun-name (name)
 220   (cond ((symbolp name) name)
 221         ((listp name)
 222          (intern (let ((*package* *pcl-package*)
 223                        (*print-case* :upcase)
 224                        (*print-pretty* nil)
 225                        (*print-gensym* t))
 226                    (format nil "~S" name))
 227                  *pcl-package*))))
 228 \f
 229 ;;; FIXME: probably no longer needed after init
 230 (defmacro precompile-random-code-segments (&optional system)
 231   `(progn
 232      (eval-when (:compile-toplevel)
 233        (update-dispatch-dfuns))
 234      (precompile-function-generators ,system)
 235      (precompile-dfun-constructors ,system)
 236      (precompile-ctors)))
 237 \f
 238 ;;; This definition is for interpreted code.
 239 (defun pcl-instance-p (x)
 240   (typep (layout-of x) 'wrapper))
 241
 242 ;;; CMU CL comment:
 243 ;;;   We define this as STANDARD-INSTANCE, since we're going to
 244 ;;;   clobber the layout with some standard-instance layout as soon as
 245 ;;;   we make it, and we want the accessor to still be type-correct.
 246 #|
 247 (defstruct (standard-instance
 248             (:predicate nil)
 249             (:constructor %%allocate-instance--class ())
 250             (:copier nil)
 251             (:alternate-metaclass instance
 252                                   cl:standard-class
 253                                   make-standard-class))
 254   (slots nil))
 255 |#
 256 (!defstruct-with-alternate-metaclass standard-instance
 257   :slot-names (slots hash-code)
 258   :boa-constructor %make-standard-instance
 259   :superclass-name instance
 260   :metaclass-name standard-classoid
 261   :metaclass-constructor make-standard-classoid
 262   :dd-type structure
 263   :runtime-type-checks-p nil)
 264
 265 ;;; Both of these operations "work" on structures, which allows the above
 266 ;;; weakening of STD-INSTANCE-P.
 267 (defmacro std-instance-slots (x) `(%instance-ref ,x 1))
 268 (defmacro std-instance-wrapper (x) `(%instance-layout ,x))
 269 ;;; KLUDGE: This one doesn't "work" on structures.  However, we
 270 ;;; ensure, in SXHASH and friends, never to call it on structures.
 271 (defmacro std-instance-hash (x) `(%instance-ref ,x 2))
 272
 273 ;;; FIXME: These functions are called every place we do a
 274 ;;; CALL-NEXT-METHOD, and probably other places too. It's likely worth
 275 ;;; selectively optimizing them with DEFTRANSFORMs and stuff, rather
 276 ;;; than just indiscriminately expanding them inline everywhere.
 277 (declaim (inline get-slots get-slots-or-nil))
 278 (declaim (ftype (function (t) simple-vector) get-slots))
 279 (declaim (ftype (function (t) (or simple-vector null)) get-slots-or-nil))
 280 (defun get-slots (instance)
 281   (if (std-instance-p instance)
 282       (std-instance-slots instance)
 283       (fsc-instance-slots instance)))
 284 (defun get-slots-or-nil (instance)
 285   ;; Suppress a code-deletion note.  FIXME: doing the FIXME above,
 286   ;; integrating PCL more with the compiler, would remove the need for
 287   ;; this icky stuff.
 288   (declare (optimize (inhibit-warnings 3)))
 289   (when (pcl-instance-p instance)
 290     (get-slots instance)))
 291
 292 (defmacro built-in-or-structure-wrapper (x) `(layout-of ,x))
 293
 294 (defmacro get-wrapper (inst)
 295   (once-only ((wrapper `(wrapper-of ,inst)))
 296     `(progn
 297        (aver (typep ,wrapper 'wrapper))
 298        ,wrapper)))
 299
 300 ;;; FIXME: could be an inline function or ordinary function (like many
 301 ;;; other things around here)
 302 (defmacro get-instance-wrapper-or-nil (inst)
 303   (once-only ((wrapper `(wrapper-of ,inst)))
 304     `(if (typep ,wrapper 'wrapper)
 305          ,wrapper
 306          nil)))
 307 \f
 308 ;;;; support for useful hashing of PCL instances
 309 (let ((hash-code 0))
 310   (declare (fixnum hash-code))
 311   (defun get-instance-hash-code ()
 312     (if (< hash-code most-positive-fixnum)
 313         (incf hash-code)
 314         (setq hash-code 0))))
 315
 316 (defun sb-impl::sxhash-instance (x)
 317   (cond
 318     ((std-instance-p x) (std-instance-hash x))
 319     ((fsc-instance-p x) (fsc-instance-hash x))
 320     (t (bug "SXHASH-INSTANCE called on some weird thing: ~S" x))))
 321 \f
 322 ;;;; structure-instance stuff
 323 ;;;;
 324 ;;;; FIXME: Now that the code is SBCL-only, this extra layer of
 325 ;;;; abstraction around our native structure representation doesn't
 326 ;;;; seem to add anything useful, and could probably go away.
 327
 328 ;;; The definition of STRUCTURE-TYPE-P was moved to early-low.lisp.
 329
 330 (defun get-structure-dd (type)
 331   (layout-info (classoid-layout (find-classoid type))))
 332
 333 (defun structure-type-included-type-name (type)
 334   (let ((include (dd-include (get-structure-dd type))))
 335     (if (consp include)
 336         (car include)
 337         include)))
 338
 339 (defun structure-type-slot-description-list (type)
 340   (nthcdr (length (let ((include (structure-type-included-type-name type)))
 341                     (and include
 342                          (dd-slots (get-structure-dd include)))))
 343           (dd-slots (get-structure-dd type))))
 344
 345 (defun structure-slotd-name (slotd)
 346   (dsd-name slotd))
 347
 348 (defun structure-slotd-accessor-symbol (slotd)
 349   (dsd-accessor-name slotd))
 350
 351 (defun structure-slotd-reader-function (slotd)
 352   (fdefinition (dsd-accessor-name slotd)))
 353
 354 (defun structure-slotd-writer-function (slotd)
 355   (unless (dsd-read-only slotd)
 356     (fdefinition `(setf ,(dsd-accessor-name slotd)))))
 357
 358 (defun structure-slotd-type (slotd)
 359   (dsd-type slotd))
 360
 361 (defun structure-slotd-init-form (slotd)
 362   (dsd-default slotd))