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[emacs.git] / lisp / emacs-lisp / disass.el
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1 ;;; disass.el --- disassembler for compiled Emacs Lisp code
3 ;; Copyright (C) 1986, 1991, 2002-2015 Free Software Foundation, Inc.
5 ;; Author: Doug Cutting <doug@csli.stanford.edu>
6 ;; Jamie Zawinski <jwz@lucid.com>
7 ;; Maintainer: emacs-devel@gnu.org
8 ;; Keywords: internal
10 ;; This file is part of GNU Emacs.
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.
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.
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/>.
25 ;;; Commentary:
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.
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.
36 ;;; Code:
38 (require 'macroexp)
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")
45 (defvar disassemble-column-1-indent 8 "*")
46 (defvar disassemble-column-2-indent 10 "*")
48 (defvar disassemble-recursive-indent 3 "*")
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)
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))
154 (insert "Uncompiled body: ")
155 (let ((print-escape-newlines t))
156 (prin1 (macroexp-progn obj)
157 (current-buffer))))))
158 (if interactive-p
159 (message "")))
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)
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
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
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
255 (+ indent disassemble-recursive-indent)))
256 arg))
258 ;; really just a constant
259 (let ((print-escape-newlines t))
260 (prin1 arg (current-buffer))))))
262 (insert "\n")))))
263 nil)
265 (provide 'disass)
267 ;;; disass.el ends here