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

   1 ;;; disass.el --- disassembler for compiled Emacs Lisp code  -*- lexical-binding:t -*-
   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 (functionp object)))
  61       (setq object `(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 (when (symbolp obj)
  76                 (prog1 obj
  77                   (setq obj (indirect-function obj)))))
  78         args)
  79     (setq obj (autoload-do-load obj name))
  80     (if (subrp obj)
  81         (error "Can't disassemble #<subr %s>" name))
  82     (if (eq (car-safe obj) 'macro)      ;Handle macros.
  83         (setq macro t
  84               obj (cdr obj)))
  85     (if (eq (car-safe obj) 'byte-code)
  86         (setq obj `(lambda () ,obj)))
  87     (when (consp obj)
  88       (unless (functionp obj) (error "not a function"))
  89       (if (assq 'byte-code obj)
  90           nil
  91         (if interactive-p (message (if name
  92                                        "Compiling %s's definition..."
  93                                      "Compiling definition...")
  94                                    name))
  95         (setq obj (byte-compile obj))
  96         (if interactive-p (message "Done compiling.  Disassembling..."))))
  97     (cond ((consp obj)
  98            (setq args (help-function-arglist obj))      ;save arg list
  99            (setq obj (cdr obj))         ;throw lambda away
 100            (setq obj (cdr obj)))
 101           ((byte-code-function-p obj)
 102            (setq args (help-function-arglist obj)))
 103           (t (error "Compilation failed")))
 104     (if (zerop indent) ; not a nested function
 105         (progn
 106           (indent-to indent)
 107           (insert (format "byte code%s%s%s:\n"
 108                           (if (or macro name) " for" "")
 109                           (if macro " macro" "")
 110                           (if name (format " %s" name) "")))))
 111     (let ((doc (if (consp obj)
 112                    (and (stringp (car obj)) (car obj))
 113                  ;; Use documentation to get lazy-loaded doc string
 114                  (documentation obj t))))
 115       (if (and doc (stringp doc))
 116           (progn (and (consp obj) (setq obj (cdr obj)))
 117                  (indent-to indent)
 118                  (princ "  doc:  " (current-buffer))
 119                  (if (string-match "\n" doc)
 120                      (setq doc (concat (substring doc 0 (match-beginning 0))
 121                                        " ...")))
 122                  (insert doc "\n"))))
 123     (indent-to indent)
 124     (insert "  args: ")
 125     (prin1 args (current-buffer))
 126     (insert "\n")
 127     (let ((interactive (interactive-form obj)))
 128       (if interactive
 129           (progn
 130             (setq interactive (nth 1 interactive))
 131             (if (eq (car-safe (car-safe obj)) 'interactive)
 132                 (setq obj (cdr obj)))
 133             (indent-to indent)
 134             (insert " interactive: ")
 135             (if (eq (car-safe interactive) 'byte-code)
 136                 (progn
 137                   (insert "\n")
 138                   (disassemble-1 interactive
 139                                  (+ indent disassemble-recursive-indent)))
 140               (let ((print-escape-newlines t))
 141                 (prin1 interactive (current-buffer))))
 142             (insert "\n"))))
 143     (cond ((and (consp obj) (assq 'byte-code obj))
 144            (disassemble-1 (assq 'byte-code obj) indent))
 145           ((byte-code-function-p obj)
 146            (disassemble-1 obj indent))
 147           (t
 148            (insert "Uncompiled body:  ")
 149            (let ((print-escape-newlines t))
 150              (prin1 (macroexp-progn obj)
 151                     (current-buffer))))))
 152   (if interactive-p
 153       (message "")))
 154
 155
 156 (defun disassemble-1 (obj indent)
 157   "Prints the byte-code call OBJ in the current buffer.
 158 OBJ should be a call to BYTE-CODE generated by the byte compiler."
 159   (let (bytes constvec)
 160     (if (consp obj)
 161         (setq bytes (car (cdr obj))             ;the byte code
 162               constvec (car (cdr (cdr obj))))   ;constant vector
 163       ;; If it is lazy-loaded, load it now
 164       (fetch-bytecode obj)
 165       (setq bytes (aref obj 1)
 166             constvec (aref obj 2)))
 167     (let ((lap (byte-decompile-bytecode (string-as-unibyte bytes) constvec))
 168           op arg opname pc-value)
 169       (let ((tagno 0)
 170             tmp
 171             (lap lap))
 172         (while (setq tmp (assq 'TAG lap))
 173           (setcar (cdr tmp) (setq tagno (1+ tagno)))
 174           (setq lap (cdr (memq tmp lap)))))
 175       (while lap
 176         ;; Take off the pc value of the next thing
 177         ;; and put it in pc-value.
 178         (setq pc-value nil)
 179         (if (numberp (car lap))
 180             (setq pc-value (car lap)
 181                   lap (cdr lap)))
 182         ;; Fetch the next op and its arg.
 183         (setq op (car (car lap))
 184               arg (cdr (car lap)))
 185         (setq lap (cdr lap))
 186         (indent-to indent)
 187         (if (eq 'TAG op)
 188             (progn
 189               ;; We have a label.  Display it, but first its pc value.
 190               (if pc-value
 191                   (insert (format "%d:" pc-value)))
 192               (insert (int-to-string (car arg))))
 193           ;; We have an instruction.  Display its pc value first.
 194           (if pc-value
 195               (insert (format "%d" pc-value)))
 196           (indent-to (+ indent disassemble-column-1-indent))
 197           (if (and op
 198                    (string-match "^byte-" (setq opname (symbol-name op))))
 199               (setq opname (substring opname 5))
 200             (setq opname "<not-an-opcode>"))
 201           (if (eq op 'byte-constant2)
 202               (insert " #### shouldn't have seen constant2 here!\n  "))
 203           (insert opname)
 204           (indent-to (+ indent disassemble-column-1-indent
 205                         disassemble-column-2-indent
 206                         -1))
 207           (insert " ")
 208           (cond ((memq op byte-goto-ops)
 209                  (insert (int-to-string (nth 1 arg))))
 210                 ((memq op '(byte-call byte-unbind
 211                             byte-listN byte-concatN byte-insertN
 212                             byte-stack-ref byte-stack-set byte-stack-set2
 213                             byte-discardN byte-discardN-preserve-tos))
 214                  (insert (int-to-string arg)))
 215                 ((memq op '(byte-varref byte-varset byte-varbind))
 216                  (prin1 (car arg) (current-buffer)))
 217                 ((memq op '(byte-constant byte-constant2))
 218                  ;; it's a constant
 219                  (setq arg (car arg))
 220                  ;; but if the value of the constant is compiled code, then
 221                  ;; recursively disassemble it.
 222                  (cond ((or (byte-code-function-p arg)
 223                             (and (consp arg) (functionp arg)
 224                                  (assq 'byte-code arg))
 225                             (and (eq (car-safe arg) 'macro)
 226                                  (or (byte-code-function-p (cdr arg))
 227                                      (and (consp (cdr arg))
 228                                           (functionp (cdr arg))
 229                                           (assq 'byte-code (cdr arg))))))
 230                         (cond ((byte-code-function-p arg)
 231                                (insert "<compiled-function>\n"))
 232                               ((functionp arg)
 233                                (insert "<compiled lambda>"))
 234                               (t (insert "<compiled macro>\n")))
 235                         (disassemble-internal
 236                          arg
 237                          (+ indent disassemble-recursive-indent 1)
 238                          nil))
 239                        ((eq (car-safe arg) 'byte-code)
 240                         (insert "<byte code>\n")
 241                         (disassemble-1  ;recurse on byte-code object
 242                          arg
 243                          (+ indent disassemble-recursive-indent)))
 244                        ((eq (car-safe (car-safe arg)) 'byte-code)
 245                         (insert "(<byte code>...)\n")
 246                         (mapc ;recurse on list of byte-code objects
 247                          (lambda (obj)
 248                            (disassemble-1
 249                             obj
 250                             (+ indent disassemble-recursive-indent)))
 251                          arg))
 252                        (t
 253                         ;; really just a constant
 254                         (let ((print-escape-newlines t))
 255                           (prin1 arg (current-buffer))))))
 256                 )
 257           (insert "\n")))))
 258   nil)
 259
 260 (provide 'disass)
 261
 262 ;;; disass.el ends here