lisp/emacs-lisp/disass.el

   1 ;;; disass.el --- disassembler for compiled Emacs Lisp code
   2
   3 ;; Copyright (C) 1986, 1991, 2002-2015 Free Software Foundation, Inc.
   4
   5 ;; Author: Doug Cutting <doug@csli.stanford.edu>
   6 ;;      Jamie Zawinski <jwz@lucid.com>
   7 ;; Maintainer: emacs-devel@gnu.org
   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 (require 'macroexp)
  39
  40 ;;; The variable byte-code-vector is defined by the new bytecomp.el.
  41 ;;; The function byte-decompile-lapcode is defined in byte-opt.el.
  42 ;;; Since we don't use byte-decompile-lapcode, let's try not loading byte-opt.
  43 (require 'byte-compile "bytecomp")
  44
  45 (defvar disassemble-column-1-indent 8 "*")
  46 (defvar disassemble-column-2-indent 10 "*")
  47
  48 (defvar disassemble-recursive-indent 3 "*")
  49
  50 ;;;###autoload
  51 (defun disassemble (object &optional buffer indent interactive-p)
  52   "Print disassembled code for OBJECT in (optional) BUFFER.
  53 OBJECT can be a symbol defined as a function, or a function itself
  54 \(a lambda expression or a compiled-function object).
  55 If OBJECT is not already compiled, we compile it, but do not
  56 redefine OBJECT if it is a symbol."
  57   (interactive (list (intern (completing-read "Disassemble function: "
  58                                               obarray 'fboundp t))
  59                      nil 0 t))
  60   (if (and (consp object) (not (eq (car object) 'lambda)))
  61       (setq object (list 'lambda () object)))
  62   (or indent (setq indent 0))           ;Default indent to zero
  63   (save-excursion
  64     (if (or interactive-p (null buffer))
  65         (with-output-to-temp-buffer "*Disassemble*"
  66           (set-buffer "*Disassemble*")
  67           (disassemble-internal object indent (not interactive-p)))
  68       (set-buffer buffer)
  69       (disassemble-internal object indent nil)))
  70   nil)
  71
  72
  73 (defun disassemble-internal (obj indent interactive-p)
  74   (let ((macro 'nil)
  75         (name 'nil)
  76         (doc 'nil)
  77         args)
  78     (while (symbolp obj)
  79       (setq name obj
  80             obj (symbol-function obj)))
  81     (if (subrp obj)
  82         (error "Can't disassemble #<subr %s>" name))
  83     (setq obj (autoload-do-load obj name))
  84     (if (eq (car-safe obj) 'macro)      ;Handle macros.
  85         (setq macro t
  86               obj (cdr obj)))
  87     (if (and (listp obj) (eq (car obj) 'byte-code))
  88         (setq obj (list 'lambda nil obj)))
  89     (if (and (listp obj) (not (eq (car obj) 'lambda)))
  90         (error "not a function"))
  91     (if (consp obj)
  92         (if (assq 'byte-code obj)
  93             nil
  94           (if interactive-p (message (if name
  95                                          "Compiling %s's definition..."
  96                                        "Compiling definition...")
  97                                      name))
  98           (setq obj (byte-compile obj))
  99           (if interactive-p (message "Done compiling.  Disassembling..."))))
 100     (cond ((consp obj)
 101            (setq obj (cdr obj))         ;throw lambda away
 102            (setq args (car obj))        ;save arg list
 103            (setq obj (cdr obj)))
 104           ((byte-code-function-p obj)
 105            (setq args (aref obj 0)))
 106           (t (error "Compilation failed")))
 107     (if (zerop indent) ; not a nested function
 108         (progn
 109           (indent-to indent)
 110           (insert (format "byte code%s%s%s:\n"
 111                           (if (or macro name) " for" "")
 112                           (if macro " macro" "")
 113                           (if name (format " %s" name) "")))))
 114     (let ((doc (if (consp obj)
 115                    (and (stringp (car obj)) (car obj))
 116                  ;; Use documentation to get lazy-loaded doc string
 117                  (documentation obj t))))
 118       (if (and doc (stringp doc))
 119           (progn (and (consp obj) (setq obj (cdr obj)))
 120                  (indent-to indent)
 121                  (princ "  doc:  " (current-buffer))
 122                  (if (string-match "\n" doc)
 123                      (setq doc (concat (substring doc 0 (match-beginning 0))
 124                                        " ...")))
 125                  (insert doc "\n"))))
 126     (indent-to indent)
 127     (insert "  args: ")
 128     (prin1 args (current-buffer))
 129     (insert "\n")
 130     (let ((interactive (cond ((consp obj)
 131                               (assq 'interactive obj))
 132                              ((> (length obj) 5)
 133                               (list 'interactive (aref obj 5))))))
 134       (if interactive
 135           (progn
 136             (setq interactive (nth 1 interactive))
 137             (if (eq (car-safe (car-safe obj)) 'interactive)
 138                 (setq obj (cdr obj)))
 139             (indent-to indent)
 140             (insert " interactive: ")
 141             (if (eq (car-safe interactive) 'byte-code)
 142                 (progn
 143                   (insert "\n")
 144                   (disassemble-1 interactive
 145                                  (+ indent disassemble-recursive-indent)))
 146               (let ((print-escape-newlines t))
 147                 (prin1 interactive (current-buffer))))
 148             (insert "\n"))))
 149     (cond ((and (consp obj) (assq 'byte-code obj))
 150            (disassemble-1 (assq 'byte-code obj) indent))
 151           ((byte-code-function-p obj)
 152            (disassemble-1 obj indent))
 153           (t
 154            (insert "Uncompiled body:  ")
 155            (let ((print-escape-newlines t))
 156              (prin1 (macroexp-progn obj)
 157                     (current-buffer))))))
 158   (if interactive-p
 159       (message "")))
 160
 161
 162 (defun disassemble-1 (obj indent)
 163   "Prints the byte-code call OBJ in the current buffer.
 164 OBJ should be a call to BYTE-CODE generated by the byte compiler."
 165   (let (bytes constvec)
 166     (if (consp obj)
 167         (setq bytes (car (cdr obj))             ;the byte code
 168               constvec (car (cdr (cdr obj))))   ;constant vector
 169       ;; If it is lazy-loaded, load it now
 170       (fetch-bytecode obj)
 171       (setq bytes (aref obj 1)
 172             constvec (aref obj 2)))
 173     (let ((lap (byte-decompile-bytecode (string-as-unibyte bytes) constvec))
 174           op arg opname pc-value)
 175       (let ((tagno 0)
 176             tmp
 177             (lap lap))
 178         (while (setq tmp (assq 'TAG lap))
 179           (setcar (cdr tmp) (setq tagno (1+ tagno)))
 180           (setq lap (cdr (memq tmp lap)))))
 181       (while lap
 182         ;; Take off the pc value of the next thing
 183         ;; and put it in pc-value.
 184         (setq pc-value nil)
 185         (if (numberp (car lap))
 186             (setq pc-value (car lap)
 187                   lap (cdr lap)))
 188         ;; Fetch the next op and its arg.
 189         (setq op (car (car lap))
 190               arg (cdr (car lap)))
 191         (setq lap (cdr lap))
 192         (indent-to indent)
 193         (if (eq 'TAG op)
 194             (progn
 195               ;; We have a label.  Display it, but first its pc value.
 196               (if pc-value
 197                   (insert (format "%d:" pc-value)))
 198               (insert (int-to-string (car arg))))
 199           ;; We have an instruction.  Display its pc value first.
 200           (if pc-value
 201               (insert (format "%d" pc-value)))
 202           (indent-to (+ indent disassemble-column-1-indent))
 203           (if (and op
 204                    (string-match "^byte-" (setq opname (symbol-name op))))
 205               (setq opname (substring opname 5))
 206             (setq opname "<not-an-opcode>"))
 207           (if (eq op 'byte-constant2)
 208               (insert " #### shouldn't have seen constant2 here!\n  "))
 209           (insert opname)
 210           (indent-to (+ indent disassemble-column-1-indent
 211                         disassemble-column-2-indent
 212                         -1))
 213           (insert " ")
 214           (cond ((memq op byte-goto-ops)
 215                  (insert (int-to-string (nth 1 arg))))
 216                 ((memq op '(byte-call byte-unbind
 217                             byte-listN byte-concatN byte-insertN
 218                             byte-stack-ref byte-stack-set byte-stack-set2
 219                             byte-discardN byte-discardN-preserve-tos))
 220                  (insert (int-to-string arg)))
 221                 ((memq op '(byte-varref byte-varset byte-varbind))
 222                  (prin1 (car arg) (current-buffer)))
 223                 ((memq op '(byte-constant byte-constant2))
 224                  ;; it's a constant
 225                  (setq arg (car arg))
 226                  ;; but if the value of the constant is compiled code, then
 227                  ;; recursively disassemble it.
 228                  (cond ((or (byte-code-function-p arg)
 229                             (and (eq (car-safe arg) 'lambda)
 230                                  (assq 'byte-code arg))
 231                             (and (eq (car-safe arg) 'macro)
 232                                  (or (byte-code-function-p (cdr arg))
 233                                      (and (eq (car-safe (cdr arg)) 'lambda)
 234                                           (assq 'byte-code (cdr arg))))))
 235                         (cond ((byte-code-function-p arg)
 236                                (insert "<compiled-function>\n"))
 237                               ((eq (car-safe arg) 'lambda)
 238                                (insert "<compiled lambda>"))
 239                               (t (insert "<compiled macro>\n")))
 240                         (disassemble-internal
 241                          arg
 242                          (+ indent disassemble-recursive-indent 1)
 243                          nil))
 244                        ((eq (car-safe arg) 'byte-code)
 245                         (insert "<byte code>\n")
 246                         (disassemble-1  ;recurse on byte-code object
 247                          arg
 248                          (+ indent disassemble-recursive-indent)))
 249                        ((eq (car-safe (car-safe arg)) 'byte-code)
 250                         (insert "(<byte code>...)\n")
 251                         (mapc ;recurse on list of byte-code objects
 252                          (lambda (obj)
 253                            (disassemble-1
 254                             obj
 255                             (+ indent disassemble-recursive-indent)))
 256                          arg))
 257                        (t
 258                         ;; really just a constant
 259                         (let ((print-escape-newlines t))
 260                           (prin1 arg (current-buffer))))))
 261                 )
 262           (insert "\n")))))
 263   nil)
 264
 265 (provide 'disass)
 266
 267 ;;; disass.el ends here