module/language/objcode/spec.scm

   1 ;;; Guile Lowlevel Intermediate Language
   2
   3 ;; Copyright (C) 2001, 2009 Free Software Foundation, Inc.
   4
   5 ;;;; This library is free software; you can redistribute it and/or
   6 ;;;; modify it under the terms of the GNU Lesser General Public
   7 ;;;; License as published by the Free Software Foundation; either
   8 ;;;; version 3 of the License, or (at your option) any later version.
   9 ;;;;
  10 ;;;; This library is distributed in the hope that it will be useful,
  11 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 ;;;; Lesser General Public License for more details.
  14 ;;;;
  15 ;;;; You should have received a copy of the GNU Lesser General Public
  16 ;;;; License along with this library; if not, write to the Free Software
  17 ;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  18
  19 ;;; Code:
  20
  21 (define-module (language objcode spec)
  22   #:use-module (system base language)
  23   #:use-module (system vm objcode)
  24   #:use-module (system vm program)
  25   #:export (objcode))
  26
  27 (define (objcode->value x e opts)
  28   (let ((thunk (make-program x #f #f)))
  29     (if (eq? e (current-module))
  30         ;; save a cons in this case
  31         (values (thunk) e e)
  32         (save-module-excursion
  33          (lambda ()
  34            (set-current-module e)
  35            (values (thunk) e e))))))
  36
  37 ;; since locals are allocated on the stack and can have limited scope,
  38 ;; in many cases we use one local for more than one lexical variable. so
  39 ;; the returned locals set is a list, where element N of the list is
  40 ;; itself a list of bindings for local variable N.
  41 (define (collapse-locals locs)
  42   (let lp ((ret '()) (locs locs))
  43     (if (null? locs)
  44         (map cdr (sort! ret
  45                         (lambda (x y) (< (car x) (car y)))))
  46         (let ((b (car locs)))
  47           (cond
  48            ((assv-ref ret (binding:index b))
  49             => (lambda (bindings)
  50                  (append! bindings (list b))
  51                  (lp ret (cdr locs))))
  52            (else
  53             (lp (acons (binding:index b) (list b) ret)
  54                 (cdr locs))))))))
  55
  56 (define (decompile-value x env opts)
  57   (cond
  58    ((program? x)
  59     (let ((objs  (program-objects x))
  60           (meta  (program-meta x))
  61           (free-vars  (program-free-variables x))
  62           (binds (program-bindings x))
  63           (srcs  (program-sources x)))
  64       (let ((blocs (and binds (collapse-locals binds))))
  65         (values (program-objcode x)
  66                 `((objects . ,objs)
  67                   (meta    . ,(and meta (meta)))
  68                   (free-vars . ,free-vars)
  69                   (blocs   . ,blocs)
  70                   (sources . ,srcs))))))
  71    ((objcode? x)
  72     (values x #f))
  73    (else
  74     (error "can't decompile ~A: not a program or objcode" x))))
  75
  76 (define-language objcode
  77   #:title       "Guile Object Code"
  78   #:version     "0.3"
  79   #:reader      #f
  80   #:printer     write-objcode
  81   #:compilers   `((value . ,objcode->value))
  82   #:decompilers `((value . ,decompile-value))
  83   )