FM / vm

/usr/share/guile/2.0/system/vm

Name	Size	Mode	Actions
coverage.scm	15640	0644	edit dl rm
frame.scm	6147	0644	edit dl rm
inspect.scm	6119	0644	edit dl rm
instruction.scm	1166	0644	edit dl rm
objcode.scm	1141	0644	edit dl rm
program.scm	11032	0644	edit dl rm
trace.scm	5476	0644	edit dl rm
trap-state.scm	10373	0644	edit dl rm
traps.scm	23226	0644	edit dl rm
vm.scm	1355	0644	edit dl rm

Edit: /usr/share/guile/2.0/system/vm/frame.scm (6147B)

;;; Guile VM frame functions

;;; Copyright (C) 2001, 2005, 2009, 2010, 2011, 2012 Free Software Foundation, Inc.
;;;
;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

;;; Code:

(define-module (system vm frame)
  #:use-module (system base pmatch)
  #:use-module (system vm program)
  #:use-module (system vm instruction)
  #:use-module (system vm objcode)
  #:export (frame-bindings
            frame-lookup-binding
            frame-binding-ref frame-binding-set!
            frame-next-source frame-call-representation
            frame-environment
            frame-object-binding frame-object-name
            frame-return-values))

(define (frame-bindings frame)
  (let ((p (frame-procedure frame)))
    (if (program? p)
        (program-bindings-for-ip p (frame-instruction-pointer frame))
        '())))

(define (frame-lookup-binding frame var)
  (let lp ((bindings (frame-bindings frame)))
    (cond ((null? bindings)
           #f)
          ((eq? (binding:name (car bindings)) var)
           (car bindings))
          (else
           (lp (cdr bindings))))))

(define (frame-binding-set! frame var val)
  (frame-local-set! frame
                    (binding:index
                     (or (frame-lookup-binding frame var)
                         (error "variable not bound in frame" var frame)))
                    val))

(define (frame-binding-ref frame var)
  (frame-local-ref frame
                   (binding:index
                    (or (frame-lookup-binding frame var)
                        (error "variable not bound in frame" var frame)))))

;; This function is always called to get some sort of representation of the
;; frame to present to the user, so let's do the logical thing and dispatch to
;; frame-call-representation.
(define (frame-arguments frame)
  (cdr (frame-call-representation frame)))

;;;
;;; Pretty printing
;;;

(define (frame-next-source frame)
  (let ((proc (frame-procedure frame)))
    (if (program? proc)
        (program-source proc
                        (frame-instruction-pointer frame)
                        (program-sources-pre-retire proc))
        '())))

;; Basically there are two cases to deal with here:
;;
;;   1. We've already parsed the arguments, and bound them to local
;;      variables. In a standard (lambda (a b c) ...) call, this doesn't
;;      involve any argument shuffling; but with rest, optional, or
;;      keyword arguments, the arguments as given to the procedure may
;;      not correspond to what's on the stack. We reconstruct the
;;      arguments using e.g. for the case above: `(,a ,b ,c). This works
;;      for rest arguments too: (a b . c) => `(,a ,b . ,c)
;;
;;   2. We have failed to parse the arguments. Perhaps it's the wrong
;;      number of arguments, or perhaps we're doing a typed dispatch and
;;      the types don't match. In that case the arguments are all on the
;;      stack, and nothing else is on the stack.

(define (frame-call-representation frame)
  (let ((p (frame-procedure frame)))
    (cons
     (or (false-if-exception (procedure-name p)) p)
     (cond
      ((and (program? p)
            (program-arguments-alist p (frame-instruction-pointer frame)))
       ;; case 1
       => (lambda (arguments)
            (define (binding-ref sym i)
              (cond
               ((frame-lookup-binding frame sym)
                => (lambda (b) (frame-local-ref frame (binding:index b))))
               ((< i (frame-num-locals frame))
                (frame-local-ref frame i))
               (else
                ;; let's not error here, as we are called during backtraces...
                '???)))
            (let lp ((req (or (assq-ref arguments 'required) '()))
                     (opt (or (assq-ref arguments 'optional) '()))
                     (key (or (assq-ref arguments 'keyword) '()))
                     (rest (or (assq-ref arguments 'rest) #f))
                     (i 0))
              (cond
               ((pair? req)
                (cons (binding-ref (car req) i)
                      (lp (cdr req) opt key rest (1+ i))))
               ((pair? opt)
                (cons (binding-ref (car opt) i)
                      (lp req (cdr opt) key rest (1+ i))))
               ((pair? key)
                (cons* (caar key)
                       (frame-local-ref frame (cdar key))
                       (lp req opt (cdr key) rest (1+ i))))
               (rest
                (binding-ref rest i))
               (else
                '())))))
      (else
       ;; case 2
       (map (lambda (i)
              (frame-local-ref frame i))
            (iota (frame-num-locals frame))))))))

;;; Misc
;;;

(define (frame-environment frame)
  (map (lambda (binding)
	 (cons (binding:name binding) (frame-binding-ref frame binding)))
       (frame-bindings frame)))

(define (frame-object-binding frame obj)
  (do ((bs (frame-bindings frame) (cdr bs)))
      ((or (null? bs) (eq? obj (frame-binding-ref frame (car bs))))
       (and (pair? bs) (car bs)))))

(define (frame-object-name frame obj)
  (cond ((frame-object-binding frame obj) => binding:name)
	(else #f)))

;; Nota bene, only if frame is in a return context (i.e. in a
;; pop-continuation hook dispatch).
(define (frame-return-values frame)
  (let* ((len (frame-num-locals frame))
         (nvalues (frame-local-ref frame (1- len))))
    (map (lambda (i)
           (frame-local-ref frame (+ (- len nvalues 1) i)))
         (iota nvalues))))

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