src/code/host-alieneval.lisp

   1 ;;;; the part of the Alien implementation which is needed at
   2 ;;;; cross-compilation time
   3
   4 ;;;; This software is part of the SBCL system. See the README file for
   5 ;;;; more information.
   6 ;;;;
   7 ;;;; This software is derived from the CMU CL system, which was
   8 ;;;; written at Carnegie Mellon University and released into the
   9 ;;;; public domain. The software is in the public domain and is
  10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
  11 ;;;; files for more information.
  12
  13 (in-package "SB!ALIEN")
  14
  15 (/show0 "host-alieneval.lisp 15")
  16 \f
  17 ;;;; utility functions
  18
  19 (defun align-offset (offset alignment)
  20   (let ((extra (rem offset alignment)))
  21     (if (zerop extra) offset (+ offset (- alignment extra)))))
  22
  23 (defun guess-alignment (bits)
  24   (cond ((null bits) nil)
  25         #!-(or x86 (and ppc darwin)) ((> bits 32) 64)
  26         ((> bits 16) 32)
  27         ((> bits 8) 16)
  28         ((> bits 1) 8)
  29         (t 1)))
  30 \f
  31 ;;;; ALIEN-TYPE-INFO stuff
  32
  33 (eval-when (#-sb-xc :compile-toplevel :execute :load-toplevel)
  34
  35 (defstruct (alien-type-class (:copier nil))
  36   (name nil :type symbol)
  37   (include nil :type (or null alien-type-class))
  38   (unparse nil :type (or null function))
  39   (type= nil :type (or null function))
  40   (lisp-rep nil :type (or null function))
  41   (alien-rep nil :type (or null function))
  42   (extract-gen nil :type (or null function))
  43   (deposit-gen nil :type (or null function))
  44   (naturalize-gen nil :type (or null function))
  45   (deport-gen nil :type (or null function))
  46   ;; Cast?
  47   (arg-tn nil :type (or null function))
  48   (result-tn nil :type (or null function))
  49   (subtypep nil :type (or null function)))
  50 (def!method print-object ((type-class alien-type-class) stream)
  51   (print-unreadable-object (type-class stream :type t)
  52     (prin1 (alien-type-class-name type-class) stream)))
  53
  54 (defun alien-type-class-or-lose (name)
  55   (or (gethash name *alien-type-classes*)
  56       (error "no alien type class ~S" name)))
  57
  58 (defun create-alien-type-class-if-necessary (name include)
  59   (let ((old (gethash name *alien-type-classes*))
  60         (include (and include (alien-type-class-or-lose include))))
  61     (if old
  62         (setf (alien-type-class-include old) include)
  63         (setf (gethash name *alien-type-classes*)
  64               (make-alien-type-class :name name :include include)))))
  65
  66 (defparameter *method-slot-alist*
  67   '((:unparse . alien-type-class-unparse)
  68     (:type= . alien-type-class-type=)
  69     (:subtypep . alien-type-class-subtypep)
  70     (:lisp-rep . alien-type-class-lisp-rep)
  71     (:alien-rep . alien-type-class-alien-rep)
  72     (:extract-gen . alien-type-class-extract-gen)
  73     (:deposit-gen . alien-type-class-deposit-gen)
  74     (:naturalize-gen . alien-type-class-naturalize-gen)
  75     (:deport-gen . alien-type-class-deport-gen)
  76     ;; cast?
  77     (:arg-tn . alien-type-class-arg-tn)
  78     (:result-tn . alien-type-class-result-tn)))
  79
  80 (defun method-slot (method)
  81   (cdr (or (assoc method *method-slot-alist*)
  82            (error "no method ~S" method))))
  83
  84 ) ; EVAL-WHEN
  85
  86 ;;; We define a keyword "BOA" constructor so that we can reference the
  87 ;;; slot names in init forms.
  88 (def!macro define-alien-type-class ((name &key include include-args)
  89                                     &rest slots)
  90   (let ((defstruct-name (symbolicate "ALIEN-" name "-TYPE")))
  91     (multiple-value-bind (include include-defstruct overrides)
  92         (etypecase include
  93           (null
  94            (values nil 'alien-type nil))
  95           (symbol
  96            (values
  97             include
  98             (symbolicate "ALIEN-" include "-TYPE")
  99             nil))
 100           (list
 101            (values
 102             (car include)
 103             (symbolicate "ALIEN-" (car include) "-TYPE")
 104             (cdr include))))
 105       `(progn
 106          (eval-when (:compile-toplevel :load-toplevel :execute)
 107            (create-alien-type-class-if-necessary ',name ',(or include 'root)))
 108          (def!struct (,defstruct-name
 109                         (:include ,include-defstruct
 110                                   (class ',name)
 111                                   ,@overrides)
 112                         (:constructor
 113                          ,(symbolicate "MAKE-" defstruct-name)
 114                          (&key class bits alignment
 115                                ,@(mapcar (lambda (x)
 116                                            (if (atom x) x (car x)))
 117                                          slots)
 118                                ,@include-args
 119                                ;; KLUDGE
 120                                &aux (alignment (or alignment (guess-alignment bits))))))
 121            ,@slots)))))
 122
 123 (def!macro define-alien-type-method ((class method) lambda-list &rest body)
 124   (let ((defun-name (symbolicate class "-" method "-METHOD")))
 125     `(progn
 126        (defun ,defun-name ,lambda-list
 127          ,@body)
 128        (setf (,(method-slot method) (alien-type-class-or-lose ',class))
 129              #',defun-name))))
 130
 131 (def!macro invoke-alien-type-method (method type &rest args)
 132   (let ((slot (method-slot method)))
 133     (once-only ((type type))
 134       `(funcall (do ((class (alien-type-class-or-lose (alien-type-class ,type))
 135                             (alien-type-class-include class)))
 136                     ((null class)
 137                      (error "method ~S not defined for ~S"
 138                             ',method (alien-type-class ,type)))
 139                   (let ((fn (,slot class)))
 140                     (when fn
 141                       (return fn))))
 142                 ,type ,@args))))
 143 \f
 144 ;;;; type parsing and unparsing
 145
 146 ;;; CMU CL used COMPILER-LET to bind *AUXILIARY-TYPE-DEFINITIONS*, and
 147 ;;; COMPILER-LET is no longer supported by ANSI or SBCL. Instead, we
 148 ;;; follow the suggestion in CLTL2 of using SYMBOL-MACROLET to achieve
 149 ;;; a similar effect.
 150 (eval-when (#-sb-xc :compile-toplevel :load-toplevel :execute)
 151   (defun auxiliary-type-definitions (env)
 152     (multiple-value-bind (result expanded-p)
 153         (sb!xc:macroexpand '&auxiliary-type-definitions& env)
 154       (if expanded-p
 155           result
 156           ;; This is like having the global symbol-macro definition be
 157           ;; NIL, but global symbol-macros make me vaguely queasy, so
 158           ;; I do it this way instead.
 159           nil))))
 160
 161 ;;; Process stuff in a new scope.
 162 (def!macro with-auxiliary-alien-types (env &body body)
 163   ``(symbol-macrolet ((&auxiliary-type-definitions&
 164                        ,(append *new-auxiliary-types*
 165                                 (auxiliary-type-definitions ,env))))
 166       ,(let ((*new-auxiliary-types* nil))
 167          ,@body)))
 168
 169 ;;; Parse TYPE as an alien type specifier and return the resultant
 170 ;;; ALIEN-TYPE structure.
 171 (defun parse-alien-type (type env)
 172   (declare (type (or sb!kernel:lexenv null) env))
 173   (if (consp type)
 174       (let ((translator (info :alien-type :translator (car type))))
 175         (unless translator
 176           (error "unknown alien type: ~S" type))
 177         (funcall translator type env))
 178       (ecase (info :alien-type :kind type)
 179         (:primitive
 180          (let ((translator (info :alien-type :translator type)))
 181            (unless translator
 182              (error "no translator for primitive alien type ~S" type))
 183            (funcall translator (list type) env)))
 184         (:defined
 185          (or (info :alien-type :definition type)
 186              (error "no definition for alien type ~S" type)))
 187         (:unknown
 188          (error "unknown alien type: ~S" type)))))
 189
 190 (defun auxiliary-alien-type (kind name env)
 191   (declare (type (or sb!kernel:lexenv null) env))
 192   (flet ((aux-defn-matches (x)
 193            (and (eq (first x) kind) (eq (second x) name))))
 194     (let ((in-auxiliaries
 195            (or (find-if #'aux-defn-matches *new-auxiliary-types*)
 196                (find-if #'aux-defn-matches (auxiliary-type-definitions env)))))
 197       (if in-auxiliaries
 198           (values (third in-auxiliaries) t)
 199           (ecase kind
 200             (:struct
 201              (info :alien-type :struct name))
 202             (:union
 203              (info :alien-type :union name))
 204             (:enum
 205              (info :alien-type :enum name)))))))
 206
 207 (defun (setf auxiliary-alien-type) (new-value kind name env)
 208   (declare (type (or sb!kernel:lexenv null) env))
 209   (flet ((aux-defn-matches (x)
 210            (and (eq (first x) kind) (eq (second x) name))))
 211     (when (find-if #'aux-defn-matches *new-auxiliary-types*)
 212       (error "attempt to multiply define ~A ~S" kind name))
 213     (when (find-if #'aux-defn-matches (auxiliary-type-definitions env))
 214       (error "attempt to shadow definition of ~A ~S" kind name)))
 215   (push (list kind name new-value) *new-auxiliary-types*)
 216   new-value)
 217
 218 (defun verify-local-auxiliaries-okay ()
 219   (dolist (info *new-auxiliary-types*)
 220     (destructuring-bind (kind name defn) info
 221       (declare (ignore defn))
 222       (when (ecase kind
 223               (:struct
 224                (info :alien-type :struct name))
 225               (:union
 226                (info :alien-type :union name))
 227               (:enum
 228                (info :alien-type :enum name)))
 229         (error "attempt to shadow definition of ~A ~S" kind name)))))
 230
 231 (defun unparse-alien-type (type)
 232   #!+sb-doc
 233   "Convert the alien-type structure TYPE back into a list specification of
 234    the type."
 235   (declare (type alien-type type))
 236   (let ((*record-types-already-unparsed* nil))
 237     (%unparse-alien-type type)))
 238
 239 ;;; Does all the work of UNPARSE-ALIEN-TYPE. It's separate because we
 240 ;;; need to recurse inside the binding of
 241 ;;; *RECORD-TYPES-ALREADY-UNPARSED*.
 242 (defun %unparse-alien-type (type)
 243   (invoke-alien-type-method :unparse type))
 244 \f
 245 ;;;; alien type defining stuff
 246
 247 (def!macro define-alien-type-translator (name lambda-list &body body)
 248   (with-unique-names (whole env)
 249     (let ((defun-name (symbolicate "ALIEN-" name "-TYPE-TRANSLATOR")))
 250       (multiple-value-bind (body decls docs)
 251           (sb!kernel:parse-defmacro lambda-list whole body name
 252                                     'define-alien-type-translator
 253                                     :environment env)
 254         `(eval-when (:compile-toplevel :load-toplevel :execute)
 255            (defun ,defun-name (,whole ,env)
 256              (declare (ignorable ,env))
 257              ,@decls
 258              (block ,name
 259                ,body))
 260            (%define-alien-type-translator ',name #',defun-name ,docs))))))
 261
 262 (eval-when (#-sb-xc :compile-toplevel :load-toplevel :execute)
 263   (defun %define-alien-type-translator (name translator docs)
 264     (declare (ignore docs))
 265     (setf (info :alien-type :kind name) :primitive)
 266     (setf (info :alien-type :translator name) translator)
 267     (clear-info :alien-type :definition name)
 268     #+nil
 269     (setf (fdocumentation name 'alien-type) docs)
 270     name))
 271
 272 (def!macro define-alien-type (name type &environment env)
 273   #!+sb-doc
 274   "Define the alien type NAME to be equivalent to TYPE. Name may be NIL for
 275    STRUCT and UNION types, in which case the name is taken from the type
 276    specifier."
 277   (with-auxiliary-alien-types env
 278     (let ((alien-type (parse-alien-type type env)))
 279       `(eval-when (:compile-toplevel :load-toplevel :execute)
 280          ,@(when *new-auxiliary-types*
 281              `((%def-auxiliary-alien-types ',*new-auxiliary-types*)))
 282          ,@(when name
 283              `((%define-alien-type ',name ',alien-type)))))))
 284 (def!macro def-alien-type (&rest rest)
 285   (deprecation-warning 'def-alien-type 'define-alien-type)
 286   `(define-alien-type ,@rest))
 287
 288 (eval-when (#-sb-xc :compile-toplevel :load-toplevel :execute)
 289   (defun %def-auxiliary-alien-types (types)
 290     (dolist (info types)
 291       (destructuring-bind (kind name defn) info
 292         (macrolet ((frob (kind)
 293                          `(let ((old (info :alien-type ,kind name)))
 294                             (unless (or (null old) (alien-type-= old defn))
 295                               (warn
 296                                "redefining ~A ~S to be:~%  ~S,~%was:~%  ~S"
 297                                kind name defn old))
 298                             (setf (info :alien-type ,kind name) defn))))
 299           (ecase kind
 300             (:struct (frob :struct))
 301             (:union (frob :union))
 302             (:enum (frob :enum)))))))
 303   (defun %define-alien-type (name new)
 304     (ecase (info :alien-type :kind name)
 305       (:primitive
 306        (error "~S is a built-in alien type." name))
 307       (:defined
 308        (let ((old (info :alien-type :definition name)))
 309          (unless (or (null old) (alien-type-= new old))
 310            (warn "redefining ~S to be:~%  ~S,~%was~%  ~S"
 311                  name
 312                  (unparse-alien-type new)
 313                  (unparse-alien-type old)))))
 314       (:unknown))
 315     (setf (info :alien-type :definition name) new)
 316     (setf (info :alien-type :kind name) :defined)
 317     name))
 318 \f
 319 ;;;; the root alien type
 320
 321 (eval-when (:compile-toplevel :load-toplevel :execute)
 322   (create-alien-type-class-if-necessary 'root nil))
 323
 324 (def!struct (alien-type
 325              (:make-load-form-fun sb!kernel:just-dump-it-normally)
 326              (:constructor make-alien-type (&key class bits alignment
 327                                             &aux (alignment (or alignment (guess-alignment bits))))))
 328   (class 'root :type symbol)
 329   (bits nil :type (or null unsigned-byte))
 330   (alignment nil :type (or null unsigned-byte)))
 331 (def!method print-object ((type alien-type) stream)
 332   (print-unreadable-object (type stream :type t)
 333     (prin1 (unparse-alien-type type) stream)))
 334 \f
 335 ;;;; the SAP type
 336
 337 (define-alien-type-class (system-area-pointer))
 338
 339 (define-alien-type-translator system-area-pointer ()
 340   (make-alien-system-area-pointer-type
 341    :bits #!-alpha sb!vm:n-word-bits #!+alpha 64))
 342
 343 (define-alien-type-method (system-area-pointer :unparse) (type)
 344   (declare (ignore type))
 345   'system-area-pointer)
 346
 347 (define-alien-type-method (system-area-pointer :lisp-rep) (type)
 348   (declare (ignore type))
 349   'system-area-pointer)
 350
 351 (define-alien-type-method (system-area-pointer :alien-rep) (type)
 352   (declare (ignore type))
 353   'system-area-pointer)
 354
 355 (define-alien-type-method (system-area-pointer :naturalize-gen) (type alien)
 356   (declare (ignore type))
 357   alien)
 358
 359 (define-alien-type-method (system-area-pointer :deport-gen) (type object)
 360   (declare (ignore type))
 361   (/noshow "doing alien type method SYSTEM-AREA-POINTER :DEPORT-GEN" object)
 362   object)
 363
 364 (define-alien-type-method (system-area-pointer :extract-gen) (type sap offset)
 365   (declare (ignore type))
 366   `(sap-ref-sap ,sap (/ ,offset sb!vm:n-byte-bits)))
 367 \f
 368 ;;;; the ALIEN-VALUE type
 369
 370 (define-alien-type-class (alien-value :include system-area-pointer))
 371
 372 (define-alien-type-method (alien-value :lisp-rep) (type)
 373   (declare (ignore type))
 374   nil)
 375
 376 (define-alien-type-method (alien-value :naturalize-gen) (type alien)
 377   `(%sap-alien ,alien ',type))
 378
 379 (define-alien-type-method (alien-value :deport-gen) (type value)
 380   (declare (ignore type))
 381   (/noshow "doing alien type method ALIEN-VALUE :DEPORT-GEN" value)
 382   `(alien-sap ,value))
 383 \f
 384 ;;; HEAP-ALIEN-INFO -- defstruct.
 385 ;;;
 386 ;;; Information describing a heap-allocated alien.
 387 (def!struct (heap-alien-info
 388              (:make-load-form-fun sb!kernel:just-dump-it-normally))
 389   ;; The type of this alien.
 390   (type (missing-arg) :type alien-type)
 391   ;; The form to evaluate to produce the SAP pointing to where in the heap
 392   ;; it is.
 393   (sap-form (missing-arg)))
 394 (def!method print-object ((info heap-alien-info) stream)
 395   (print-unreadable-object (info stream :type t)
 396     (funcall (formatter "~S ~S")
 397              stream
 398              (heap-alien-info-sap-form info)
 399              (unparse-alien-type (heap-alien-info-type info)))))
 400 \f
 401 ;;;; Interfaces to the different methods
 402
 403 (defun alien-type-= (type1 type2)
 404   #!+sb-doc
 405   "Return T iff TYPE1 and TYPE2 describe equivalent alien types."
 406   (or (eq type1 type2)
 407       (and (eq (alien-type-class type1)
 408                (alien-type-class type2))
 409            (invoke-alien-type-method :type= type1 type2))))
 410
 411 (defun alien-subtype-p (type1 type2)
 412   #!+sb-doc
 413   "Return T iff the alien type TYPE1 is a subtype of TYPE2. Currently, the
 414    only supported subtype relationships are is that any pointer type is a
 415    subtype of (* t), and any array type first dimension will match
 416    (array <eltype> nil ...). Otherwise, the two types have to be
 417    ALIEN-TYPE-=."
 418   (or (eq type1 type2)
 419       (invoke-alien-type-method :subtypep type1 type2)))
 420
 421 (defun compute-naturalize-lambda (type)
 422   `(lambda (alien ignore)
 423      (declare (ignore ignore))
 424      ,(invoke-alien-type-method :naturalize-gen type 'alien)))
 425
 426 (defun compute-deport-lambda (type)
 427   (declare (type alien-type type))
 428   (/noshow "entering COMPUTE-DEPORT-LAMBDA" type)
 429   (multiple-value-bind (form value-type)
 430       (invoke-alien-type-method :deport-gen type 'value)
 431     `(lambda (value ignore)
 432        (declare (type ,(or value-type
 433                            (compute-lisp-rep-type type)
 434                            `(alien ,type))
 435                       value)
 436                 (ignore ignore))
 437        ,form)))
 438
 439 (defun compute-extract-lambda (type)
 440   `(lambda (sap offset ignore)
 441      (declare (type system-area-pointer sap)
 442               (type unsigned-byte offset)
 443               (ignore ignore))
 444      (naturalize ,(invoke-alien-type-method :extract-gen type 'sap 'offset)
 445                  ',type)))
 446
 447 (defun compute-deposit-lambda (type)
 448   (declare (type alien-type type))
 449   `(lambda (sap offset ignore value)
 450      (declare (type system-area-pointer sap)
 451               (type unsigned-byte offset)
 452               (ignore ignore))
 453      (let ((value (deport value ',type)))
 454        ,(invoke-alien-type-method :deposit-gen type 'sap 'offset 'value)
 455        ;; Note: the reason we don't just return the pre-deported value
 456        ;; is because that would inhibit any (deport (naturalize ...))
 457        ;; optimizations that might have otherwise happen. Re-naturalizing
 458        ;; the value might cause extra consing, but is flushable, so probably
 459        ;; results in better code.
 460        (naturalize value ',type))))
 461
 462 (defun compute-lisp-rep-type (type)
 463   (invoke-alien-type-method :lisp-rep type))
 464
 465 (defun compute-alien-rep-type (type)
 466   (invoke-alien-type-method :alien-rep type))
 467 \f
 468 ;;;; default methods
 469
 470 (define-alien-type-method (root :unparse) (type)
 471   `(<unknown-alien-type> ,(type-of type)))
 472
 473 (define-alien-type-method (root :type=) (type1 type2)
 474   (declare (ignore type1 type2))
 475   t)
 476
 477 (define-alien-type-method (root :subtypep) (type1 type2)
 478   (alien-type-= type1 type2))
 479
 480 (define-alien-type-method (root :lisp-rep) (type)
 481   (declare (ignore type))
 482   nil)
 483
 484 (define-alien-type-method (root :alien-rep) (type)
 485   (declare (ignore type))
 486   '*)
 487
 488 (define-alien-type-method (root :naturalize-gen) (type alien)
 489   (declare (ignore alien))
 490   (error "cannot represent ~S typed aliens" type))
 491
 492 (define-alien-type-method (root :deport-gen) (type object)
 493   (declare (ignore object))
 494   (error "cannot represent ~S typed aliens" type))
 495
 496 (define-alien-type-method (root :extract-gen) (type sap offset)
 497   (declare (ignore sap offset))
 498   (error "cannot represent ~S typed aliens" type))
 499
 500 (define-alien-type-method (root :deposit-gen) (type sap offset value)
 501   `(setf ,(invoke-alien-type-method :extract-gen type sap offset) ,value))
 502
 503 (define-alien-type-method (root :arg-tn) (type state)
 504   (declare (ignore state))
 505   (error "Aliens of type ~S cannot be passed as arguments to CALL-OUT."
 506          (unparse-alien-type type)))
 507
 508 (define-alien-type-method (root :result-tn) (type state)
 509   (declare (ignore state))
 510   (error "Aliens of type ~S cannot be returned from CALL-OUT."
 511          (unparse-alien-type type)))
 512 \f
 513 ;;;; the INTEGER type
 514
 515 (define-alien-type-class (integer)
 516   (signed t :type (member t nil)))
 517
 518 (define-alien-type-translator signed (&optional (bits sb!vm:n-word-bits))
 519   (make-alien-integer-type :bits bits))
 520
 521 (define-alien-type-translator integer (&optional (bits sb!vm:n-word-bits))
 522   (make-alien-integer-type :bits bits))
 523
 524 (define-alien-type-translator unsigned (&optional (bits sb!vm:n-word-bits))
 525   (make-alien-integer-type :bits bits :signed nil))
 526
 527 (define-alien-type-method (integer :unparse) (type)
 528   (list (if (alien-integer-type-signed type) 'signed 'unsigned)
 529         (alien-integer-type-bits type)))
 530
 531 (define-alien-type-method (integer :type=) (type1 type2)
 532   (and (eq (alien-integer-type-signed type1)
 533            (alien-integer-type-signed type2))
 534        (= (alien-integer-type-bits type1)
 535           (alien-integer-type-bits type2))))
 536
 537 (define-alien-type-method (integer :lisp-rep) (type)
 538   (list (if (alien-integer-type-signed type) 'signed-byte 'unsigned-byte)
 539         (alien-integer-type-bits type)))
 540
 541 (define-alien-type-method (integer :alien-rep) (type)
 542   (list (if (alien-integer-type-signed type) 'signed-byte 'unsigned-byte)
 543         (alien-integer-type-bits type)))
 544
 545 (define-alien-type-method (integer :naturalize-gen) (type alien)
 546   (declare (ignore type))
 547   alien)
 548
 549 (define-alien-type-method (integer :deport-gen) (type value)
 550   (declare (ignore type))
 551   value)
 552
 553 (define-alien-type-method (integer :extract-gen) (type sap offset)
 554   (declare (type alien-integer-type type))
 555   (let ((ref-fun
 556          (if (alien-integer-type-signed type)
 557           (case (alien-integer-type-bits type)
 558             (8 'signed-sap-ref-8)
 559             (16 'signed-sap-ref-16)
 560             (32 'signed-sap-ref-32)
 561             (64 'signed-sap-ref-64))
 562           (case (alien-integer-type-bits type)
 563             (8 'sap-ref-8)
 564             (16 'sap-ref-16)
 565             (32 'sap-ref-32)
 566             (64 'sap-ref-64)))))
 567     (if ref-fun
 568         `(,ref-fun ,sap (/ ,offset sb!vm:n-byte-bits))
 569         (error "cannot extract ~W-bit integers"
 570                (alien-integer-type-bits type)))))
 571 \f
 572 ;;;; the BOOLEAN type
 573
 574 (define-alien-type-class (boolean :include integer :include-args (signed)))
 575
 576 ;;; FIXME: Check to make sure that we aren't attaching user-readable
 577 ;;; stuff to CL:BOOLEAN in any way which impairs ANSI compliance.
 578 (define-alien-type-translator boolean (&optional (bits sb!vm:n-word-bits))
 579   (make-alien-boolean-type :bits bits :signed nil))
 580
 581 (define-alien-type-method (boolean :unparse) (type)
 582   `(boolean ,(alien-boolean-type-bits type)))
 583
 584 (define-alien-type-method (boolean :lisp-rep) (type)
 585   (declare (ignore type))
 586   `(member t nil))
 587
 588 (define-alien-type-method (boolean :naturalize-gen) (type alien)
 589   (declare (ignore type))
 590   `(not (zerop ,alien)))
 591
 592 (define-alien-type-method (boolean :deport-gen) (type value)
 593   (declare (ignore type))
 594   `(if ,value 1 0))
 595 \f
 596 ;;;; the ENUM type
 597
 598 (define-alien-type-class (enum :include (integer (bits 32))
 599                                :include-args (signed))
 600   name          ; name of this enum (if any)
 601   from          ; alist from keywords to integers
 602   to            ; alist or vector from integers to keywords
 603   kind          ; kind of from mapping, :VECTOR or :ALIST
 604   offset)       ; offset to add to value for :VECTOR from mapping
 605
 606 (define-alien-type-translator enum (&whole
 607                                  type name
 608                                  &rest mappings
 609                                  &environment env)
 610   (cond (mappings
 611          (let ((result (parse-enum name mappings)))
 612            (when name
 613              (multiple-value-bind (old old-p)
 614                  (auxiliary-alien-type :enum name env)
 615                (when old-p
 616                  (unless (alien-type-= result old)
 617                    (warn "redefining alien enum ~S" name))))
 618              (setf (auxiliary-alien-type :enum name env) result))
 619            result))
 620         (name
 621          (multiple-value-bind (result found)
 622              (auxiliary-alien-type :enum name env)
 623            (unless found
 624              (error "unknown enum type: ~S" name))
 625            result))
 626         (t
 627          (error "empty enum type: ~S" type))))
 628
 629 (defun parse-enum (name elements)
 630   (when (null elements)
 631     (error "An enumeration must contain at least one element."))
 632   (let ((min nil)
 633         (max nil)
 634         (from-alist ())
 635         (prev -1))
 636     (declare (list from-alist))
 637     (dolist (el elements)
 638       (multiple-value-bind (sym val)
 639           (if (listp el)
 640               (values (first el) (second el))
 641               (values el (1+ prev)))
 642         (setf prev val)
 643         (unless (keywordp sym)
 644           (error "The enumeration element ~S is not a keyword." sym))
 645         (unless (integerp val)
 646           (error "The element value ~S is not an integer." val))
 647         (unless (and max (> max val)) (setq max val))
 648         (unless (and min (< min val)) (setq min val))
 649         (when (rassoc val from-alist)
 650           (error "The element value ~S is used more than once." val))
 651         (when (assoc sym from-alist :test #'eq)
 652           (error "The enumeration element ~S is used more than once." sym))
 653         (push (cons sym val) from-alist)))
 654     (let* ((signed (minusp min))
 655            (min-bits (if signed
 656                          (1+ (max (integer-length min)
 657                                   (integer-length max)))
 658                          (integer-length max))))
 659       (when (> min-bits 32)
 660         (error "can't represent enums needing more than 32 bits"))
 661       (setf from-alist (sort from-alist #'< :key #'cdr))
 662       (cond
 663        ;; If range is at least 20% dense, use vector mapping. Crossover
 664        ;; point solely on basis of space would be 25%. Vector mapping
 665        ;; is always faster, so give the benefit of the doubt.
 666        ((< 0.2 (/ (float (length from-alist)) (float (- max min))))
 667         ;; If offset is small and ignorable, ignore it to save time.
 668         (when (< 0 min 10) (setq min 0))
 669         (let ((to (make-array (1+ (- max min)))))
 670           (dolist (el from-alist)
 671             (setf (svref to (- (cdr el) min)) (car el)))
 672           (make-alien-enum-type :name name :signed signed
 673                                 :from from-alist :to to :kind
 674                                 :vector :offset (- min))))
 675        (t
 676         (make-alien-enum-type :name name :signed signed
 677                               :from from-alist
 678                               :to (mapcar (lambda (x) (cons (cdr x) (car x)))
 679                                           from-alist)
 680                               :kind :alist))))))
 681
 682 (define-alien-type-method (enum :unparse) (type)
 683   `(enum ,(alien-enum-type-name type)
 684          ,@(let ((prev -1))
 685              (mapcar (lambda (mapping)
 686                        (let ((sym (car mapping))
 687                              (value (cdr mapping)))
 688                          (prog1
 689                              (if (= (1+ prev) value)
 690                                  sym
 691                                  `(,sym ,value))
 692                            (setf prev value))))
 693                      (alien-enum-type-from type)))))
 694
 695 (define-alien-type-method (enum :type=) (type1 type2)
 696   (and (eq (alien-enum-type-name type1)
 697            (alien-enum-type-name type2))
 698        (equal (alien-enum-type-from type1)
 699               (alien-enum-type-from type2))))
 700
 701 (define-alien-type-method (enum :lisp-rep) (type)
 702   `(member ,@(mapcar #'car (alien-enum-type-from type))))
 703
 704 (define-alien-type-method (enum :naturalize-gen) (type alien)
 705   (ecase (alien-enum-type-kind type)
 706     (:vector
 707      `(svref ',(alien-enum-type-to type)
 708              (+ ,alien ,(alien-enum-type-offset type))))
 709     (:alist
 710      `(ecase ,alien
 711         ,@(mapcar (lambda (mapping)
 712                     `(,(car mapping) ,(cdr mapping)))
 713                   (alien-enum-type-to type))))))
 714
 715 (define-alien-type-method (enum :deport-gen) (type value)
 716   `(ecase ,value
 717      ,@(mapcar (lambda (mapping)
 718                  `(,(car mapping) ,(cdr mapping)))
 719                (alien-enum-type-from type))))
 720 \f
 721 ;;;; the FLOAT types
 722
 723 (define-alien-type-class (float)
 724   (type (missing-arg) :type symbol))
 725
 726 (define-alien-type-method (float :unparse) (type)
 727   (alien-float-type-type type))
 728
 729 (define-alien-type-method (float :lisp-rep) (type)
 730   (alien-float-type-type type))
 731
 732 (define-alien-type-method (float :alien-rep) (type)
 733   (alien-float-type-type type))
 734
 735 (define-alien-type-method (float :naturalize-gen) (type alien)
 736   (declare (ignore type))
 737   alien)
 738
 739 (define-alien-type-method (float :deport-gen) (type value)
 740   (declare (ignore type))
 741   value)
 742
 743 (define-alien-type-class (single-float :include (float (bits 32))
 744                                        :include-args (type)))
 745
 746 (define-alien-type-translator single-float ()
 747   (make-alien-single-float-type :type 'single-float))
 748
 749 (define-alien-type-method (single-float :extract-gen) (type sap offset)
 750   (declare (ignore type))
 751   `(sap-ref-single ,sap (/ ,offset sb!vm:n-byte-bits)))
 752
 753 (define-alien-type-class (double-float :include (float (bits 64))
 754                                        :include-args (type)))
 755
 756 (define-alien-type-translator double-float ()
 757   (make-alien-double-float-type :type 'double-float))
 758
 759 (define-alien-type-method (double-float :extract-gen) (type sap offset)
 760   (declare (ignore type))
 761   `(sap-ref-double ,sap (/ ,offset sb!vm:n-byte-bits)))
 762
 763 #!+long-float
 764 (define-alien-type-class (long-float :include (float (bits #!+x86 96
 765                                                            #!+sparc 128))
 766                                      :include-args (type)))
 767
 768 #!+long-float
 769 (define-alien-type-translator long-float ()
 770   (make-alien-long-float-type :type 'long-float))
 771
 772 #!+long-float
 773 (define-alien-type-method (long-float :extract-gen) (type sap offset)
 774   (declare (ignore type))
 775   `(sap-ref-long ,sap (/ ,offset sb!vm:n-byte-bits)))
 776 \f
 777 ;;;; the POINTER type
 778
 779 (define-alien-type-class (pointer :include (alien-value (bits
 780                                                          #!-alpha
 781                                                          sb!vm:n-word-bits
 782                                                          #!+alpha 64)))
 783   (to nil :type (or alien-type null)))
 784
 785 (define-alien-type-translator * (to &environment env)
 786   (make-alien-pointer-type :to (if (eq to t) nil (parse-alien-type to env))))
 787
 788 (define-alien-type-method (pointer :unparse) (type)
 789   (let ((to (alien-pointer-type-to type)))
 790     `(* ,(if to
 791              (%unparse-alien-type to)
 792              t))))
 793
 794 (define-alien-type-method (pointer :type=) (type1 type2)
 795   (let ((to1 (alien-pointer-type-to type1))
 796         (to2 (alien-pointer-type-to type2)))
 797     (if to1
 798         (if to2
 799             (alien-type-= to1 to2)
 800             nil)
 801         (null to2))))
 802
 803 (define-alien-type-method (pointer :subtypep) (type1 type2)
 804   (and (alien-pointer-type-p type2)
 805        (let ((to1 (alien-pointer-type-to type1))
 806              (to2 (alien-pointer-type-to type2)))
 807          (if to1
 808              (if to2
 809                  (alien-subtype-p to1 to2)
 810                  t)
 811              (null to2)))))
 812
 813 (define-alien-type-method (pointer :deport-gen) (type value)
 814   (/noshow "doing alien type method POINTER :DEPORT-GEN" type value)
 815   (values
 816    ;; FIXME: old version, highlighted a bug in xc optimization
 817    `(etypecase ,value
 818       (null
 819        (int-sap 0))
 820       (system-area-pointer
 821        ,value)
 822       ((alien ,type)
 823        (alien-sap ,value)))
 824    ;; new version, works around bug in xc optimization
 825    #+nil
 826    `(etypecase ,value
 827       (system-area-pointer
 828        ,value)
 829       ((alien ,type)
 830        (alien-sap ,value))
 831       (null
 832        (int-sap 0)))
 833    `(or null system-area-pointer (alien ,type))))
 834 \f
 835 ;;;; the MEM-BLOCK type
 836
 837 (define-alien-type-class (mem-block :include alien-value))
 838
 839 (define-alien-type-method (mem-block :extract-gen) (type sap offset)
 840   (declare (ignore type))
 841   `(sap+ ,sap (/ ,offset sb!vm:n-byte-bits)))
 842
 843 (define-alien-type-method (mem-block :deposit-gen) (type sap offset value)
 844   (let ((bits (alien-mem-block-type-bits type)))
 845     (unless bits
 846       (error "can't deposit aliens of type ~S (unknown size)" type))
 847     `(sb!kernel:system-area-copy ,value 0 ,sap ,offset ',bits)))
 848 \f
 849 ;;;; the ARRAY type
 850
 851 (define-alien-type-class (array :include mem-block)
 852   (element-type (missing-arg) :type alien-type)
 853   (dimensions (missing-arg) :type list))
 854
 855 (define-alien-type-translator array (ele-type &rest dims &environment env)
 856
 857   (when dims
 858     (unless (typep (first dims) '(or index null))
 859       (error "The first dimension is not a non-negative fixnum or NIL: ~S"
 860              (first dims)))
 861     (let ((loser (find-if-not (lambda (x) (typep x 'index))
 862                               (rest dims))))
 863       (when loser
 864         (error "A dimension is not a non-negative fixnum: ~S" loser))))
 865
 866   (let ((parsed-ele-type (parse-alien-type ele-type env)))
 867     (make-alien-array-type
 868      :element-type parsed-ele-type
 869      :dimensions dims
 870      :alignment (alien-type-alignment parsed-ele-type)
 871      :bits (if (and (alien-type-bits parsed-ele-type)
 872                     (every #'integerp dims))
 873                (* (align-offset (alien-type-bits parsed-ele-type)
 874                                 (alien-type-alignment parsed-ele-type))
 875                   (reduce #'* dims))))))
 876
 877 (define-alien-type-method (array :unparse) (type)
 878   `(array ,(%unparse-alien-type (alien-array-type-element-type type))
 879           ,@(alien-array-type-dimensions type)))
 880
 881 (define-alien-type-method (array :type=) (type1 type2)
 882   (and (equal (alien-array-type-dimensions type1)
 883               (alien-array-type-dimensions type2))
 884        (alien-type-= (alien-array-type-element-type type1)
 885                      (alien-array-type-element-type type2))))
 886
 887 (define-alien-type-method (array :subtypep) (type1 type2)
 888   (and (alien-array-type-p type2)
 889        (let ((dim1 (alien-array-type-dimensions type1))
 890              (dim2 (alien-array-type-dimensions type2)))
 891          (and (= (length dim1) (length dim2))
 892               (or (and dim2
 893                        (null (car dim2))
 894                        (equal (cdr dim1) (cdr dim2)))
 895                   (equal dim1 dim2))
 896               (alien-subtype-p (alien-array-type-element-type type1)
 897                                (alien-array-type-element-type type2))))))
 898 \f
 899 ;;;; the RECORD type
 900
 901 (def!struct (alien-record-field
 902              (:make-load-form-fun sb!kernel:just-dump-it-normally))
 903   (name (missing-arg) :type symbol)
 904   (type (missing-arg) :type alien-type)
 905   (bits nil :type (or unsigned-byte null))
 906   (offset 0 :type unsigned-byte))
 907 (def!method print-object ((field alien-record-field) stream)
 908   (print-unreadable-object (field stream :type t)
 909     (format stream
 910             "~S ~S~@[:~D~]"
 911             (alien-record-field-type field)
 912             (alien-record-field-name field)
 913             (alien-record-field-bits field))))
 914
 915 (define-alien-type-class (record :include mem-block)
 916   (kind :struct :type (member :struct :union))
 917   (name nil :type (or symbol null))
 918   (fields nil :type list))
 919
 920 (define-alien-type-translator struct (name &rest fields &environment env)
 921   (parse-alien-record-type :struct name fields env))
 922
 923 (define-alien-type-translator union (name &rest fields &environment env)
 924   (parse-alien-record-type :union name fields env))
 925
 926 (defun parse-alien-record-type (kind name fields env)
 927   (declare (type (or sb!kernel:lexenv null) env))
 928   (cond (fields
 929          (let* ((old (and name (auxiliary-alien-type kind name env)))
 930                 (old-fields (and old (alien-record-type-fields old))))
 931            (cond (old-fields
 932                   ;; KLUDGE: We can't easily compare the new fields
 933                   ;; against the old fields, since the old fields have
 934                   ;; already been parsed into an internal
 935                   ;; representation, so we just punt, assuming that
 936                   ;; they're consistent. -- WHN 200000505
 937                   #|
 938                   (unless (equal fields old-fields)
 939                     ;; FIXME: Perhaps this should be a warning, and we
 940                     ;; should overwrite the old definition and proceed?
 941                     (error "mismatch in fields for ~S~%  old ~S~%  new ~S"
 942                            name old-fields fields))
 943                   |#
 944                   old)
 945                  (t
 946                   (let ((new (make-alien-record-type :name name
 947                                                      :kind kind)))
 948                     (when name
 949                       (setf (auxiliary-alien-type kind name env) new))
 950                     (parse-alien-record-fields new fields env)
 951                     new)))))
 952         (name
 953          (or (auxiliary-alien-type kind name env)
 954              (setf (auxiliary-alien-type kind name env)
 955                    (make-alien-record-type :name name :kind kind))))
 956         (t
 957          (make-alien-record-type :kind kind))))
 958
 959 ;;; This is used by PARSE-ALIEN-TYPE to parse the fields of struct and
 960 ;;; union types. RESULT holds the record type we are paring the fields
 961 ;;; of, and FIELDS is the list of field specifications.
 962 (defun parse-alien-record-fields (result fields env)
 963   (declare (type alien-record-type result)
 964            (type list fields))
 965   (let ((total-bits 0)
 966         (overall-alignment 1)
 967         (parsed-fields nil))
 968     (dolist (field fields)
 969       (destructuring-bind (var type &optional bits) field
 970         (declare (ignore bits))
 971         (let* ((field-type (parse-alien-type type env))
 972                (bits (alien-type-bits field-type))
 973                (alignment (alien-type-alignment field-type))
 974                (parsed-field
 975                 (make-alien-record-field :type field-type
 976                                          :name var)))
 977           (push parsed-field parsed-fields)
 978           (when (null bits)
 979             (error "unknown size: ~S" (unparse-alien-type field-type)))
 980           (when (null alignment)
 981             (error "unknown alignment: ~S" (unparse-alien-type field-type)))
 982           (setf overall-alignment (max overall-alignment alignment))
 983           (ecase (alien-record-type-kind result)
 984             (:struct
 985              (let ((offset (align-offset total-bits alignment)))
 986                (setf (alien-record-field-offset parsed-field) offset)
 987                (setf total-bits (+ offset bits))))
 988             (:union
 989              (setf total-bits (max total-bits bits)))))))
 990     (let ((new (nreverse parsed-fields)))
 991       (setf (alien-record-type-fields result) new))
 992     (setf (alien-record-type-alignment result) overall-alignment)
 993     (setf (alien-record-type-bits result)
 994           (align-offset total-bits overall-alignment))))
 995
 996 (define-alien-type-method (record :unparse) (type)
 997   `(,(case (alien-record-type-kind type)
 998        (:struct 'struct)
 999        (:union 'union)
1000        (t '???))
1001     ,(alien-record-type-name type)
1002     ,@(unless (member type *record-types-already-unparsed* :test #'eq)
1003         (push type *record-types-already-unparsed*)
1004         (mapcar (lambda (field)
1005                   `(,(alien-record-field-name field)
1006                     ,(%unparse-alien-type (alien-record-field-type field))
1007                     ,@(if (alien-record-field-bits field)
1008                           (list (alien-record-field-bits field)))))
1009                 (alien-record-type-fields type)))))
1010
1011 ;;; Test the record fields. The depth is limiting in case of cyclic
1012 ;;; pointers.
1013 (defun record-fields-match (fields1 fields2 depth)
1014   (declare (type list fields1 fields2)
1015            (type (mod 64) depth))
1016   (labels ((record-type-= (type1 type2 depth)
1017              (and (eq (alien-record-type-name type1)
1018                       (alien-record-type-name type2))
1019                   (eq (alien-record-type-kind type1)
1020                       (alien-record-type-kind type2))
1021                   (= (length (alien-record-type-fields type1))
1022                      (length (alien-record-type-fields type2)))
1023                   (record-fields-match (alien-record-type-fields type1)
1024                                        (alien-record-type-fields type2)
1025                                        (1+ depth))))
1026            (pointer-type-= (type1 type2 depth)
1027              (let ((to1 (alien-pointer-type-to type1))
1028                    (to2 (alien-pointer-type-to type2)))
1029                (if to1
1030                    (if to2
1031                        (type-= to1 to2 (1+ depth))
1032                        nil)
1033                    (null to2))))
1034            (type-= (type1 type2 depth)
1035              (cond ((and (alien-pointer-type-p type1)
1036                          (alien-pointer-type-p type2))
1037                     (or (> depth 10)
1038                         (pointer-type-= type1 type2 depth)))
1039                    ((and (alien-record-type-p type1)
1040                          (alien-record-type-p type2))
1041                     (record-type-= type1 type2 depth))
1042                    (t
1043                     (alien-type-= type1 type2)))))
1044     (do ((fields1-rem fields1 (rest fields1-rem))
1045          (fields2-rem fields2 (rest fields2-rem)))
1046         ((or (eq fields1-rem fields2-rem)
1047              (endp fields1-rem) (endp fields2-rem))
1048          (eq fields1-rem fields2-rem))
1049       (let ((field1 (first fields1-rem))
1050             (field2 (first fields2-rem)))
1051         (declare (type alien-record-field field1 field2))
1052         (unless (and (eq (alien-record-field-name field1)
1053                          (alien-record-field-name field2))
1054                      (eql (alien-record-field-bits field1)
1055                           (alien-record-field-bits field2))
1056                      (eql (alien-record-field-offset field1)
1057                           (alien-record-field-offset field2))
1058                      (let ((field1 (alien-record-field-type field1))
1059                            (field2 (alien-record-field-type field2)))
1060                        (type-= field1 field2 (1+ depth))))
1061           (return nil))))))
1062
1063 (define-alien-type-method (record :type=) (type1 type2)
1064   (and (eq (alien-record-type-name type1)
1065            (alien-record-type-name type2))
1066        (eq (alien-record-type-kind type1)
1067            (alien-record-type-kind type2))
1068        (= (length (alien-record-type-fields type1))
1069           (length (alien-record-type-fields type2)))
1070        (record-fields-match (alien-record-type-fields type1)
1071                             (alien-record-type-fields type2) 0)))
1072 \f
1073 ;;;; the FUNCTION and VALUES alien types
1074
1075 ;;; not documented in CMU CL:-(
1076 ;;;
1077 ;;; reverse engineering observations:
1078 ;;;   * seems to be set when translating return values
1079 ;;;   * seems to enable the translation of (VALUES), which is the
1080 ;;;     Lisp idiom for C's return type "void" (which is likely
1081 ;;;     why it's set when when translating return values)
1082 (defvar *values-type-okay* nil)
1083
1084 (define-alien-type-class (fun :include mem-block)
1085   (result-type (missing-arg) :type alien-type)
1086   (arg-types (missing-arg) :type list)
1087   (stub nil :type (or null function)))
1088
1089 (define-alien-type-translator function (result-type &rest arg-types
1090                                                     &environment env)
1091   (make-alien-fun-type
1092    :result-type (let ((*values-type-okay* t))
1093                   (parse-alien-type result-type env))
1094    :arg-types (mapcar (lambda (arg-type) (parse-alien-type arg-type env))
1095                       arg-types)))
1096
1097 (define-alien-type-method (fun :unparse) (type)
1098   `(function ,(%unparse-alien-type (alien-fun-type-result-type type))
1099              ,@(mapcar #'%unparse-alien-type
1100                        (alien-fun-type-arg-types type))))
1101
1102 (define-alien-type-method (fun :type=) (type1 type2)
1103   (and (alien-type-= (alien-fun-type-result-type type1)
1104                      (alien-fun-type-result-type type2))
1105        (= (length (alien-fun-type-arg-types type1))
1106           (length (alien-fun-type-arg-types type2)))
1107        (every #'alien-type-=
1108               (alien-fun-type-arg-types type1)
1109               (alien-fun-type-arg-types type2))))
1110
1111 (define-alien-type-class (values)
1112   (values (missing-arg) :type list))
1113
1114 (define-alien-type-translator values (&rest values &environment env)
1115   (unless *values-type-okay*
1116     (error "cannot use values types here"))
1117   (let ((*values-type-okay* nil))
1118     (make-alien-values-type
1119      :values (mapcar (lambda (alien-type) (parse-alien-type alien-type env))
1120                      values))))
1121
1122 (define-alien-type-method (values :unparse) (type)
1123   `(values ,@(mapcar #'%unparse-alien-type
1124                      (alien-values-type-values type))))
1125
1126 (define-alien-type-method (values :type=) (type1 type2)
1127   (and (= (length (alien-values-type-values type1))
1128           (length (alien-values-type-values type2)))
1129        (every #'alien-type-=
1130               (alien-values-type-values type1)
1131               (alien-values-type-values type2))))
1132 \f
1133 ;;;; a structure definition needed both in the target and in the
1134 ;;;; cross-compilation host
1135
1136 ;;; information about local aliens. The WITH-ALIEN macro builds one of
1137 ;;; these structures and LOCAL-ALIEN and friends communicate
1138 ;;; information about how that local alien is represented.
1139 (def!struct (local-alien-info
1140              (:make-load-form-fun sb!kernel:just-dump-it-normally)
1141              (:constructor make-local-alien-info
1142                            (&key type force-to-memory-p
1143                             &aux (force-to-memory-p (or force-to-memory-p
1144                                                         (alien-array-type-p type)
1145                                                         (alien-record-type-p type))))))
1146   ;; the type of the local alien
1147   (type (missing-arg) :type alien-type)
1148   ;; Must this local alien be forced into memory? Using the ADDR macro
1149   ;; on a local alien will set this.
1150   (force-to-memory-p nil :type (member t nil)))
1151 (def!method print-object ((info local-alien-info) stream)
1152   (print-unreadable-object (info stream :type t)
1153     (format stream
1154             "~:[~;(forced to stack) ~]~S"
1155             (local-alien-info-force-to-memory-p info)
1156             (unparse-alien-type (local-alien-info-type info)))))
1157 \f
1158 ;;;; the ADDR macro
1159
1160 (defmacro-mundanely addr (expr &environment env)
1161   #!+sb-doc
1162   "Return an Alien pointer to the data addressed by Expr, which must be a call
1163    to SLOT or DEREF, or a reference to an Alien variable."
1164   (let ((form (sb!xc:macroexpand expr env)))
1165     (or (typecase form
1166           (cons
1167            (case (car form)
1168              (slot
1169               (cons '%slot-addr (cdr form)))
1170              (deref
1171               (cons '%deref-addr (cdr form)))
1172              (%heap-alien
1173               (cons '%heap-alien-addr (cdr form)))
1174              (local-alien
1175               (let ((info (let ((info-arg (second form)))
1176                             (and (consp info-arg)
1177                                  (eq (car info-arg) 'quote)
1178                                  (second info-arg)))))
1179                 (unless (local-alien-info-p info)
1180                   (error "Something is wrong, LOCAL-ALIEN-INFO not found: ~S"
1181                          form))
1182                 (setf (local-alien-info-force-to-memory-p info) t))
1183               (cons '%local-alien-addr (cdr form)))))
1184           (symbol
1185            (let ((kind (info :variable :kind form)))
1186              (when (eq kind :alien)
1187                `(%heap-alien-addr ',(info :variable :alien-info form))))))
1188         (error "~S is not a valid L-value." form))))
1189
1190 (/show0 "host-alieneval.lisp end of file")