316 lines
12 KiB
EmacsLisp
316 lines
12 KiB
EmacsLisp
;;; disass.el --- disassembler for compiled Emacs Lisp code -*- lexical-binding:t -*-
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;; Copyright (C) 1986, 1991, 2002-2024 Free Software Foundation, Inc.
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;; Author: Doug Cutting <doug@csli.stanford.edu>
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;; Jamie Zawinski <jwz@lucid.com>
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: internal
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; The single entry point, `disassemble', disassembles a code object generated
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;; by the Emacs Lisp byte-compiler. This doesn't invert the compilation
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;; operation, not by a long shot, but it's useful for debugging.
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;;
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;; Original version by Doug Cutting (doug@csli.stanford.edu)
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;; Substantially modified by Jamie Zawinski <jwz@lucid.com> for
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;; the new lapcode-based byte compiler.
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;;; Code:
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(require 'macroexp)
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(require 'cl-lib)
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;; The variable byte-code-vector is defined by the new bytecomp.el.
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;; The function byte-decompile-lapcode is defined in byte-opt.el.
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;; Since we don't use byte-decompile-lapcode, let's try not loading byte-opt.
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(require 'byte-compile "bytecomp")
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(declare-function comp-c-func-name "comp.el")
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(defvar disassemble-column-1-indent 8 "*")
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(defvar disassemble-column-2-indent 10 "*")
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(defvar disassemble-recursive-indent 3 "*")
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;;;###autoload
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(defun disassemble (object &optional buffer indent interactive-p)
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"Print disassembled code for OBJECT in (optional) BUFFER.
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OBJECT can be a symbol defined as a function, or a function itself
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\(a lambda expression or a byte-code-function object).
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If OBJECT is not already compiled, we compile it, but do not
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redefine OBJECT if it is a symbol."
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(interactive
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(let* ((fn (function-called-at-point))
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(def (and fn (symbol-name fn))))
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(list (intern (completing-read (format-prompt "Disassemble function" fn)
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obarray 'fboundp t nil nil def))
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nil 0 t)))
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(let ((lb lexical-binding))
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(when (and (consp object) (not (eq (car object) 'lambda)))
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(setq object
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(if (eq (car object) 'byte-code)
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(apply #'make-byte-code 0 (cdr object))
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`(lambda () ,object))))
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(or indent (setq indent 0)) ;Default indent to zero
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(save-excursion
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(if (or interactive-p (null buffer))
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(with-output-to-temp-buffer "*Disassemble*"
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(set-buffer standard-output)
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(let ((lexical-binding lb))
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(disassemble-internal object indent (not interactive-p))))
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(set-buffer buffer)
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(let ((lexical-binding lb))
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(disassemble-internal object indent nil)))))
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nil)
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(declare-function native-comp-unit-file "data.c")
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(declare-function subr-native-comp-unit "data.c")
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(cl-defun disassemble-internal (obj indent interactive-p)
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(let ((macro 'nil)
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(name (when (symbolp obj)
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(prog1 obj
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(setq obj (indirect-function obj)))))
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args)
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(setq obj (autoload-do-load obj name))
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(if (subrp obj)
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(if (and (fboundp 'native-comp-function-p)
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(native-comp-function-p obj))
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(progn
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(require 'comp)
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(let ((eln (native-comp-unit-file (subr-native-comp-unit obj))))
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(if (file-exists-p eln)
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(call-process "objdump" nil (current-buffer) t "-S" eln)
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(error "Missing eln file for #<subr %s>" name)))
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(goto-char (point-min))
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(re-search-forward (concat "^.*<_?"
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(regexp-quote
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(comp-c-func-name
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(subr-name obj) "F" t))
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">:"))
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(beginning-of-line)
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(delete-region (point-min) (point))
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(when (re-search-forward "^.*<.*>:" nil t 2)
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(delete-region (match-beginning 0) (point-max)))
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(asm-mode)
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(setq buffer-read-only t)
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(cl-return-from disassemble-internal))
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(error "Can't disassemble #<subr %s>" name)))
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(if (eq (car-safe obj) 'macro) ;Handle macros.
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(setq macro t
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obj (cdr obj)))
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(when (or (consp obj) (interpreted-function-p obj))
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(unless (functionp obj) (error "Not a function"))
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(if interactive-p (message (if name
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"Compiling %s's definition..."
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"Compiling definition...")
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name))
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(setq obj (byte-compile obj))
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(if interactive-p (message "Done compiling. Disassembling...")))
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(cond ((consp obj)
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(setq args (help-function-arglist obj)) ;save arg list
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(setq obj (cdr obj)) ;throw lambda away
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(setq obj (cdr obj)))
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((closurep obj)
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(setq args (help-function-arglist obj)))
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(t (error "Compilation failed")))
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(if (zerop indent) ; not a nested function
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(progn
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(indent-to indent)
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(insert (format "byte code%s%s%s:\n"
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(if (or macro name) " for" "")
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(if macro " macro" "")
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(if name (format " %s" name) "")))))
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(let ((doc (if (consp obj)
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(and (stringp (car obj)) (car obj))
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;; Use documentation to get lazy-loaded doc string
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(documentation obj t))))
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(if (and doc (stringp doc))
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(progn (and (consp obj) (setq obj (cdr obj)))
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(indent-to indent)
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(princ " doc: " (current-buffer))
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(if (string-match "\n" doc)
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(setq doc (concat (substring doc 0 (match-beginning 0))
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" ...")))
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(insert doc "\n"))))
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(indent-to indent)
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(insert " args: ")
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(prin1 args (current-buffer))
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(insert "\n")
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(let ((interactive (interactive-form obj)))
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(if interactive
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(progn
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(setq interactive (nth 1 interactive))
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(if (eq (car-safe (car-safe obj)) 'interactive)
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(setq obj (cdr obj)))
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(indent-to indent)
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(insert " interactive: ")
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(if (eq (car-safe interactive) 'byte-code)
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(progn
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(insert "\n")
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(disassemble-1 interactive
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(+ indent disassemble-recursive-indent)))
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(let ((print-escape-newlines t))
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(prin1 interactive (current-buffer))))
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(insert "\n"))))
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(cond ((byte-code-function-p obj)
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(disassemble-1 obj indent))
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(t
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(insert "Uncompiled body: ")
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(let ((print-escape-newlines t))
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(prin1 (macroexp-progn (if (interpreted-function-p obj)
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(aref obj 1)
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obj))
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(current-buffer))))))
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(if interactive-p
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(message "")))
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(defun disassemble-1 (obj indent)
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"Print the byte-code call OBJ in the current buffer.
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OBJ should be a call to BYTE-CODE generated by the byte compiler."
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(let (bytes constvec)
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(if (consp obj)
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(setq bytes (car (cdr obj)) ;the byte code
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constvec (car (cdr (cdr obj)))) ;constant vector
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(setq bytes (aref obj 1)
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constvec (aref obj 2)))
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(cl-assert (not (multibyte-string-p bytes)))
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(let ((lap (byte-decompile-bytecode bytes constvec))
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op arg opname pc-value)
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(let ((tagno 0)
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tmp
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(lap lap))
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(while (setq tmp (assq 'TAG lap))
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(setcar (cdr tmp) (setq tagno (1+ tagno)))
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(setq lap (cdr (memq tmp lap)))))
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(while lap
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;; Take off the pc value of the next thing
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;; and put it in pc-value.
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(setq pc-value nil)
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(if (numberp (car lap))
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(setq pc-value (car lap)
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lap (cdr lap)))
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;; Fetch the next op and its arg.
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(setq op (car (car lap))
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arg (cdr (car lap)))
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(setq lap (cdr lap))
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(indent-to indent)
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(if (eq 'TAG op)
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(progn
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;; We have a label. Display it, but first its pc value.
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(if pc-value
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(insert (format "%d:" pc-value)))
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(insert (int-to-string (car arg))))
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;; We have an instruction. Display its pc value first.
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(if pc-value
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(insert (format "%d" pc-value)))
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(indent-to (+ indent disassemble-column-1-indent))
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(if (and op
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(string-match "^byte-" (setq opname (symbol-name op))))
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(setq opname (substring opname 5))
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(setq opname "<not-an-opcode>"))
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(if (eq op 'byte-constant2)
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(insert " #### shouldn't have seen constant2 here!\n "))
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(insert opname)
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(indent-to (+ indent disassemble-column-1-indent
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disassemble-column-2-indent
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-1))
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(insert " ")
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(cond ((memq op byte-goto-ops)
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(insert (int-to-string (nth 1 arg))))
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((memq op '(byte-call byte-unbind
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byte-listN byte-concatN byte-insertN
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byte-stack-ref byte-stack-set byte-stack-set2
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byte-discardN byte-discardN-preserve-tos))
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(insert (int-to-string arg)))
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((memq op '(byte-varref byte-varset byte-varbind))
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(prin1 (car arg) (current-buffer)))
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((memq op '(byte-constant byte-constant2))
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;; it's a constant
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(setq arg (car arg))
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;; if the succeeding op is byte-switch, display the jump table
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;; used
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(cond ((eq (car-safe (car-safe (cdr lap))) 'byte-switch)
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(insert (format "<jump-table-%s (" (hash-table-test arg)))
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(let ((first-time t))
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(maphash #'(lambda (value tag)
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(if first-time
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(setq first-time nil)
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(insert " "))
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(insert (format "%s %s" value (cadr tag))))
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arg))
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(insert ")>"))
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;; if the value of the constant is compiled code, then
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;; recursively disassemble it.
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((or (byte-code-function-p arg)
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(and (eq (car-safe arg) 'macro)
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(byte-code-function-p (cdr arg))))
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(cond ((byte-code-function-p arg)
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(insert "<byte-code-function>\n"))
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(t (insert "<compiled macro>\n")))
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(disassemble-internal
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arg
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(+ indent disassemble-recursive-indent 1)
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nil))
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((eq (car-safe arg) 'byte-code)
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(insert "<byte code>\n")
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(disassemble-1 ;recurse on byte-code object
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arg
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(+ indent disassemble-recursive-indent)))
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((eq (car-safe (car-safe arg)) 'byte-code)
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;; FIXME: I'm 99% sure bytecomp never generates
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;; this any more.
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(insert "(<byte code>...)\n")
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(mapc ;Recurse on list of byte-code objects.
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(lambda (obj)
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(disassemble-1
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obj
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(+ indent disassemble-recursive-indent)))
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arg))
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(t
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;; really just a constant
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(let ((print-escape-newlines t))
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(prin1 arg (current-buffer))))))
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)
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(insert "\n")))))
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nil)
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(defun re-disassemble (regexp &optional case-table)
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"Describe the compiled form of REGEXP in a separate window.
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If CASE-TABLE is non-nil, use it as translation table for case-folding.
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This function is mainly intended for maintenance of Emacs itself
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and may change at any time. It requires Emacs to be built with
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`--enable-checking'."
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(interactive "XRegexp (Lisp expression): ")
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(let ((desc (with-temp-buffer
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(when case-table
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(set-case-table case-table))
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(let ((case-fold-search (and case-table t)))
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(re--describe-compiled regexp)))))
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(with-output-to-temp-buffer "*Regexp-disassemble*"
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(with-current-buffer standard-output
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(insert desc)))))
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(provide 'disass)
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;;; disass.el ends here
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