code.delx.au - gnu-emacs/blob - lisp/emacs-lisp/disass.el

   1 ;;; disass.el --- disassembler for compiled Emacs Lisp code
   2
   3 ;; Copyright (C) 1986, 1991, 2002-2011 Free Software Foundation, Inc.
   4
   5 ;; Author: Doug Cutting <doug@csli.stanford.edu>
   6 ;;      Jamie Zawinski <jwz@lucid.com>
   7 ;; Maintainer: FSF
   8 ;; Keywords: internal
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; The single entry point, `disassemble', disassembles a code object generated
  28 ;; by the Emacs Lisp byte-compiler.  This doesn't invert the compilation
  29 ;; operation, not by a long shot, but it's useful for debugging.
  30
  31 ;;
  32 ;; Original version by Doug Cutting (doug@csli.stanford.edu)
  33 ;; Substantially modified by Jamie Zawinski <jwz@lucid.com> for
  34 ;; the new lapcode-based byte compiler.
  35
  36 ;;; Code:
  37
  38 ;;; The variable byte-code-vector is defined by the new bytecomp.el.
  39 ;;; The function byte-decompile-lapcode is defined in byte-opt.el.
  40 ;;; Since we don't use byte-decompile-lapcode, let's try not loading byte-opt.
  41 (require 'byte-compile "bytecomp")
  42
  43 (defvar disassemble-column-1-indent 8 "*")
  44 (defvar disassemble-column-2-indent 10 "*")
  45
  46 (defvar disassemble-recursive-indent 3 "*")
  47
  48 ;;;###autoload
  49 (defun disassemble (object &optional buffer indent interactive-p)
  50   "Print disassembled code for OBJECT in (optional) BUFFER.
  51 OBJECT can be a symbol defined as a function, or a function itself
  52 \(a lambda expression or a compiled-function object).
  53 If OBJECT is not already compiled, we compile it, but do not
  54 redefine OBJECT if it is a symbol."
  55   (interactive (list (intern (completing-read "Disassemble function: "
  56                                               obarray 'fboundp t))
  57                      nil 0 t))
  58   (if (and (consp object) (not (eq (car object) 'lambda)))
  59       (setq object (list 'lambda () object)))
  60   (or indent (setq indent 0))           ;Default indent to zero
  61   (save-excursion
  62     (if (or interactive-p (null buffer))
  63         (with-output-to-temp-buffer "*Disassemble*"
  64           (set-buffer "*Disassemble*")
  65           (disassemble-internal object indent (not interactive-p)))
  66       (set-buffer buffer)
  67       (disassemble-internal object indent nil)))
  68   nil)
  69
  70
  71 (defun disassemble-internal (obj indent interactive-p)
  72   (let ((macro 'nil)
  73         (name 'nil)
  74         (doc 'nil)
  75         args)
  76     (while (symbolp obj)
  77       (setq name obj
  78             obj (symbol-function obj)))
  79     (if (subrp obj)
  80         (error "Can't disassemble #<subr %s>" name))
  81     (if (and (listp obj) (eq (car obj) 'autoload))
  82         (progn
  83           (load (nth 1 obj))
  84           (setq obj (symbol-function name))))
  85     (if (eq (car-safe obj) 'macro)      ;handle macros
  86         (setq macro t
  87               obj (cdr obj)))
  88     (if (and (listp obj) (eq (car obj) 'byte-code))
  89         (setq obj (list 'lambda nil obj)))
  90     (if (and (listp obj) (not (eq (car obj) 'lambda)))
  91         (error "not a function"))
  92     (if (consp obj)
  93         (if (assq 'byte-code obj)
  94             nil
  95           (if interactive-p (message (if name
  96                                          "Compiling %s's definition..."
  97                                        "Compiling definition...")
  98                                      name))
  99           (setq obj (byte-compile obj))
 100           (if interactive-p (message "Done compiling.  Disassembling..."))))
 101     (cond ((consp obj)
 102            (setq obj (cdr obj))         ;throw lambda away
 103            (setq args (car obj))        ;save arg list
 104            (setq obj (cdr obj)))
 105           ((byte-code-function-p obj)
 106            (setq args (aref obj 0)))
 107           (t (error "Compilation failed")))
 108     (if (zerop indent) ; not a nested function
 109         (progn
 110           (indent-to indent)
 111           (insert (format "byte code%s%s%s:\n"
 112                           (if (or macro name) " for" "")
 113                           (if macro " macro" "")
 114                           (if name (format " %s" name) "")))))
 115     (let ((doc (if (consp obj)
 116                    (and (stringp (car obj)) (car obj))
 117                  ;; Use documentation to get lazy-loaded doc string
 118                  (documentation obj t))))
 119       (if (and doc (stringp doc))
 120           (progn (and (consp obj) (setq obj (cdr obj)))
 121                  (indent-to indent)
 122                  (princ "  doc:  " (current-buffer))
 123                  (if (string-match "\n" doc)
 124                      (setq doc (concat (substring doc 0 (match-beginning 0))
 125                                        " ...")))
 126                  (insert doc "\n"))))
 127     (indent-to indent)
 128     (insert "  args: ")
 129     (prin1 args (current-buffer))
 130     (insert "\n")
 131     (let ((interactive (cond ((consp obj)
 132                               (assq 'interactive obj))
 133                              ((> (length obj) 5)
 134                               (list 'interactive (aref obj 5))))))
 135       (if interactive
 136           (progn
 137             (setq interactive (nth 1 interactive))
 138             (if (eq (car-safe (car-safe obj)) 'interactive)
 139                 (setq obj (cdr obj)))
 140             (indent-to indent)
 141             (insert " interactive: ")
 142             (if (eq (car-safe interactive) 'byte-code)
 143                 (progn
 144                   (insert "\n")
 145                   (disassemble-1 interactive
 146                                  (+ indent disassemble-recursive-indent)))
 147               (let ((print-escape-newlines t))
 148                 (prin1 interactive (current-buffer))))
 149             (insert "\n"))))
 150     (cond ((and (consp obj) (assq 'byte-code obj))
 151            (disassemble-1 (assq 'byte-code obj) indent))
 152           ((byte-code-function-p obj)
 153            (disassemble-1 obj indent))
 154           (t
 155            (insert "Uncompiled body:  ")
 156            (let ((print-escape-newlines t))
 157              (prin1 (if (cdr obj) (cons 'progn obj) (car obj))
 158                     (current-buffer))))))
 159   (if interactive-p
 160       (message "")))
 161
 162
 163 (defun disassemble-1 (obj indent)
 164   "Prints the byte-code call OBJ in the current buffer.
 165 OBJ should be a call to BYTE-CODE generated by the byte compiler."
 166   (let (bytes constvec)
 167     (if (consp obj)
 168         (setq bytes (car (cdr obj))             ;the byte code
 169               constvec (car (cdr (cdr obj))))   ;constant vector
 170       ;; If it is lazy-loaded, load it now
 171       (fetch-bytecode obj)
 172       (setq bytes (aref obj 1)
 173             constvec (aref obj 2)))
 174     (let ((lap (byte-decompile-bytecode (string-as-unibyte bytes) constvec))
 175           op arg opname pc-value)
 176       (let ((tagno 0)
 177             tmp
 178             (lap lap))
 179         (while (setq tmp (assq 'TAG lap))
 180           (setcar (cdr tmp) (setq tagno (1+ tagno)))
 181           (setq lap (cdr (memq tmp lap)))))
 182       (while lap
 183         ;; Take off the pc value of the next thing
 184         ;; and put it in pc-value.
 185         (setq pc-value nil)
 186         (if (numberp (car lap))
 187             (setq pc-value (car lap)
 188                   lap (cdr lap)))
 189         ;; Fetch the next op and its arg.
 190         (setq op (car (car lap))
 191               arg (cdr (car lap)))
 192         (setq lap (cdr lap))
 193         (indent-to indent)
 194         (if (eq 'TAG op)
 195             (progn
 196               ;; We have a label.  Display it, but first its pc value.
 197               (if pc-value
 198                   (insert (format "%d:" pc-value)))
 199               (insert (int-to-string (car arg))))
 200           ;; We have an instruction.  Display its pc value first.
 201           (if pc-value
 202               (insert (format "%d" pc-value)))
 203           (indent-to (+ indent disassemble-column-1-indent))
 204           (if (and op
 205                    (string-match "^byte-" (setq opname (symbol-name op))))
 206               (setq opname (substring opname 5))
 207             (setq opname "<not-an-opcode>"))
 208           (if (eq op 'byte-constant2)
 209               (insert " #### shouldn't have seen constant2 here!\n  "))
 210           (insert opname)
 211           (indent-to (+ indent disassemble-column-1-indent
 212                         disassemble-column-2-indent
 213                         -1))
 214           (insert " ")
 215           (cond ((memq op byte-goto-ops)
 216                  (insert (int-to-string (nth 1 arg))))
 217                 ((memq op '(byte-call byte-unbind
 218                             byte-listN byte-concatN byte-insertN))
 219                  (insert (int-to-string arg)))
 220                 ((memq op '(byte-varref byte-varset byte-varbind))
 221                  (prin1 (car arg) (current-buffer)))
 222                 ((memq op '(byte-constant byte-constant2))
 223                  ;; it's a constant
 224                  (setq arg (car arg))
 225                  ;; but if the value of the constant is compiled code, then
 226                  ;; recursively disassemble it.
 227                  (cond ((or (byte-code-function-p arg)
 228                             (and (eq (car-safe arg) 'lambda)
 229                                  (assq 'byte-code arg))
 230                             (and (eq (car-safe arg) 'macro)
 231                                  (or (byte-code-function-p (cdr arg))
 232                                      (and (eq (car-safe (cdr arg)) 'lambda)
 233                                           (assq 'byte-code (cdr arg))))))
 234                         (cond ((byte-code-function-p arg)
 235                                (insert "<compiled-function>\n"))
 236                               ((eq (car-safe arg) 'lambda)
 237                                (insert "<compiled lambda>"))
 238                               (t (insert "<compiled macro>\n")))
 239                         (disassemble-internal
 240                          arg
 241                          (+ indent disassemble-recursive-indent 1)
 242                          nil))
 243                        ((eq (car-safe arg) 'byte-code)
 244                         (insert "<byte code>\n")
 245                         (disassemble-1  ;recurse on byte-code object
 246                          arg
 247                          (+ indent disassemble-recursive-indent)))
 248                        ((eq (car-safe (car-safe arg)) 'byte-code)
 249                         (insert "(<byte code>...)\n")
 250                         (mapc ;recurse on list of byte-code objects
 251                          '(lambda (obj)
 252                             (disassemble-1
 253                              obj
 254                              (+ indent disassemble-recursive-indent)))
 255                          arg))
 256                        (t
 257                         ;; really just a constant
 258                         (let ((print-escape-newlines t))
 259                           (prin1 arg (current-buffer))))))
 260                 )
 261           (insert "\n")))))
 262   nil)
 263
 264 (provide 'disass)
 265
 266 ;;; disass.el ends here