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;;; Guile VM code converters
;; Copyright (C) 2001, 2009 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 (language glil decompile-assembly)
#:use-module (system base pmatch)
#:use-module (system vm program)
#:use-module (language assembly)
#:use-module (language glil)
#:export (decompile-assembly))
(define (decompile-assembly x env opts)
(values (decompile-toplevel x)
env))
(define (decompile-toplevel x)
(pmatch x
((load-program ,nargs ,nrest ,nlocs ,labels ,len ,meta . ,body)
(decompile-load-program nargs nrest nlocs
(decompile-meta meta)
body labels #f))
(else
(error "invalid assembly" x))))
(define (decompile-meta meta)
(and meta
(let ((prog (decompile-toplevel meta)))
(if (and (glil-program? prog)
(= (length (glil-program-body prog)) 2)
(glil-const? (car (glil-program-body prog))))
(glil-const-obj (car (glil-program-body prog)))
(error "metadata not a thunk returning a const" prog)))))
(define *placeholder* (list 'placeholder))
(define (emit-constants l out)
(let lp ((in (reverse l)) (out out))
(cond ((null? in) out)
((eq? (car in) *placeholder*) (lp (cdr in) out))
((glil-program? (car in)) (lp (cdr in) (cons (car in) out)))
(else (lp (cdr in) (cons (make-glil-const (car l)) out))))))
(define (decompile-load-program nargs nrest nlocs meta body labels
objects)
(let ((glil-labels (sort (map (lambda (x)
(cons (cdr x) (make-glil-label (car x))))
labels)
(lambda (x y) (< (car x) (car y)))))
(bindings (sort (if meta (car meta) '())
(lambda (x y) (< (binding:start x) (binding:start y)))))
(unbindings (sort (if meta (car meta) '())
(lambda (x y) (< (binding:end x) (binding:end y)))))
(sources (if meta (cadr meta) '()))
(filename #f)
(props (if meta (cddr meta) '())))
(define (pop-bindings! addr)
(let lp ((in bindings) (out '()))
(if (or (null? in) (> (binding:start (car in)) addr))
(begin
(set! bindings in)
(if (null? out) #f (reverse out)))
(lp (cdr in) (cons (car in) out)))))
(define (pop-unbindings! addr)
(let lp ((in unbindings) (out '()))
(if (or (null? in) (> (binding:end (car in)) addr))
(begin
(set! unbindings in)
(if (null? out) #f (reverse out)))
(lp (cdr in) (cons (car in) out)))))
(define (pop-source! addr)
;; a fragile algorithm.
(cond ((null? sources) #f)
((eq? (caar sources) 'filename)
(set! filename (cdar sources))
(pop-source! addr))
((eqv? (caar sources) addr)
(let ((x (car sources)))
(set! sources (cdr sources))
`((filename . ,filename)
(line . ,(cadr x))
(column . ,(cddr x)))))
(else #f)))
(let lp ((in body) (stack '()) (out '()) (pos 0))
(cond
((null? in)
(or (null? stack) (error "leftover stack insts" stack body))
(make-glil-program nargs nrest nlocs props (reverse out) #f))
((pop-bindings! pos)
=> (lambda (bindings)
(lp in stack
(cons (make-glil-bind bindings)
out)
pos)))
((pop-unbindings! pos)
=> (lambda (bindings)
(lp in stack (cons (make-glil-unbind) out) pos)))
((pop-source! pos)
=> (lambda (s)
(lp in stack (cons (make-glil-source s) out) pos)))
((and (or (null? out) (not (glil-label? (car out))))
(assv-ref glil-labels pos))
=> (lambda (label)
(lp in stack (cons label out) pos)))
(else
(pmatch (car in)
((nop)
(lp (cdr in) stack out (1+ pos)))
((make-false)
(lp (cdr in) (cons #f stack) out (1+ pos)))
((load-program ,a ,b ,c ,d ,labels ,sublen ,meta . ,body)
(lp (cdr in)
(cons (decompile-load-program a b c d (decompile-meta meta)
body labels (car stack))
(cdr stack))
out
(+ pos (byte-length (car in)))))
((load-symbol ,str)
(lp (cdr in) (cons (string->symbol str) stack) out
(+ pos 1 (string-length str))))
((make-int8:0)
(lp (cdr in) (cons 0 stack) out (1+ pos)))
((make-int8:1)
(lp (cdr in) (cons 1 stack) out (1+ pos)))
((make-int8 ,n)
(lp (cdr in) (cons n stack) out (+ pos 2)))
((cons)
(let ((head (list-head stack 2))
(stack (list-tail stack 2)))
(if (memq *placeholder* head)
(lp (cdr in) (cons *placeholder* stack)
(cons (make-glil-call 'cons 2) (emit-constants head out))
(+ pos 1))
(lp (cdr in) (cons (cons (cadr head) (car head)) stack)
out (+ pos 3)))))
((list ,a ,b)
(let* ((len (+ (ash a 8) b))
(head (list-head stack len))
(stack (list-tail stack len)))
(if (memq *placeholder* head)
(lp (cdr in) (cons *placeholder* stack)
(cons (make-glil-call 'list len) (emit-constants head out))
(+ pos 3))
(lp (cdr in) (cons (reverse head) stack) out (+ pos 3)))))
((make-eol)
(lp (cdr in) (cons '() stack) out (1+ pos)))
((return)
(lp (cdr in) (cdr stack)
(cons (make-glil-call 'return 1)
(emit-constants (list-head stack 1) out))
(1+ pos)))
((local-ref ,n)
(lp (cdr in) (cons *placeholder* stack)
(cons (make-glil-local 'ref n)
out) (+ pos 2)))
((local-set ,n)
(lp (cdr in) (cdr stack)
(cons (make-glil-local 'set n)
(emit-constants (list-head stack 1) out))
(+ pos 2)))
((br-if-not ,l)
(lp (cdr in) (cdr stack)
(cons (make-glil-branch 'br-if-not l) out)
(+ pos 3)))
((mul)
(lp (cdr in) (cons *placeholder* (cddr stack))
(cons (make-glil-call 'mul 2)
(emit-constants (list-head stack 2) out))
(+ pos 1)))
((goto/args ,n)
(lp (cdr in) (list-tail stack (1+ n))
(cons (make-glil-call 'goto/args n)
(emit-constants (list-head stack (1+ n)) out))
(+ pos 2)))
(else (error "unsupported decompilation" (car in)))))))))
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