admin/find-gc.el

   1 ;;; find-gc.el --- detect functions that call the garbage collector
   2
   3 ;; Copyright (C) 1992, 2001-2018 Free Software Foundation, Inc.
   4
   5 ;; Maintainer: emacs-devel@gnu.org
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software: you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation, either version 3 of the License, or
  12 ;; (at your option) any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
  21
  22 ;;; Commentary:
  23
  24 ;; Produce in find-gc-unsafe-list the set of all functions that may invoke GC.
  25 ;; This expects the Emacs sources to live in find-gc-source-directory.
  26
  27 ;;; Code:
  28
  29 (defvar find-gc-unsafe-list nil
  30   "The list of unsafe functions is placed here by `find-gc-unsafe'.")
  31
  32 (defvar find-gc-source-directory
  33   (file-name-as-directory (expand-file-name "src" source-directory))
  34   "Directory containing Emacs C sources.")
  35
  36 (defvar find-gc-subrs-callers nil
  37   "Alist of users of subrs, from GC testing.
  38 Each entry has the form (FUNCTION . FUNCTIONS-THAT-CALL-IT).")
  39
  40 (defvar find-gc-subrs-called nil
  41   "Alist of subrs called, in GC testing.
  42 Each entry has the form (FUNCTION . FUNCTIONS-IT-CALLS).")
  43
  44
  45 ;;; Functions on this list are safe, even if they appear to be able
  46 ;;; to call the target.
  47
  48 (defvar find-gc-noreturn-list '(Fsignal Fthrow wrong_type_argument))
  49
  50 ;;; This was originally generated directory-files, but there were
  51 ;;; too many files there that were not actually compiled.  The
  52 ;;; list below was created for a HP-UX 7.0 system.
  53
  54 (defvar find-gc-source-files
  55   '("dispnew.c" "scroll.c" "xdisp.c" "window.c"
  56     "term.c" "cm.c" "emacs.c" "keyboard.c" "macros.c"
  57     "keymap.c" "sysdep.c" "buffer.c" "filelock.c"
  58     "insdel.c" "marker.c" "minibuf.c" "fileio.c"
  59     "dired.c" "cmds.c" "casefiddle.c"
  60     "indent.c" "search.c" "regex.c" "undo.c"
  61     "alloc.c" "data.c" "doc.c" "editfns.c"
  62     "callint.c" "eval.c" "fns.c" "print.c" "lread.c"
  63     "syntax.c" "unexcoff.c"
  64     "bytecode.c" "process.c" "callproc.c" "doprnt.c"
  65     "xterm.c" "xfns.c"))
  66
  67
  68 (defun find-gc-unsafe ()
  69   "Return a list of unsafe functions--that is, which can call GC.
  70 Also store it in `find-gc-unsafe-list'."
  71   (trace-call-tree nil)
  72   (trace-use-tree)
  73   (find-unsafe-funcs 'Fgarbage_collect)
  74   (setq find-gc-unsafe-list
  75         (sort find-gc-unsafe-list
  76               (function (lambda (x y)
  77                           (string-lessp (car x) (car y)))))))
  78
  79 ;;; This does a depth-first search to find all functions that can
  80 ;;; ultimately call the function "target".  The result is an a-list
  81 ;;; in find-gc-unsafe-list; the cars are the unsafe functions, and the cdrs
  82 ;;; are (one of) the unsafe functions that these functions directly
  83 ;;; call.
  84
  85 (defun find-unsafe-funcs (target)
  86   (setq find-gc-unsafe-list (list (list target)))
  87   (trace-unsafe target))
  88
  89 (defun trace-unsafe (func)
  90   (let ((used (assq func find-gc-subrs-callers)))
  91     (or used
  92         (error "No find-gc-subrs-callers for %s" (car find-gc-unsafe-list)))
  93     (while (setq used (cdr used))
  94       (or (assq (car used) find-gc-unsafe-list)
  95           (memq (car used) find-gc-noreturn-list)
  96           (progn
  97             (push (cons (car used) func) find-gc-unsafe-list)
  98             (trace-unsafe (car used)))))))
  99
 100
 101
 102
 103 (defun trace-call-tree (&optional ignored)
 104   (message "Setting up directories...")
 105   (setq find-gc-subrs-called nil)
 106   (let ((case-fold-search nil)
 107         (default-directory find-gc-source-directory)
 108         (files find-gc-source-files)
 109         name entry rtlfile)
 110     (dolist (file files)
 111       (message "Compiling %s..." file)
 112       (call-process "gcc" nil nil nil "-I" "." "-I" "../lib"
 113                     "-fdump-rtl-expand" "-o" null-device "-c" file)
 114       (setq rtlfile
 115             (file-expand-wildcards (format "%s.*.expand" file) t))
 116       (if (/= 1 (length rtlfile))
 117           (message "Error compiling `%s'?" file)
 118         (with-temp-buffer
 119           (insert-file-contents (setq rtlfile (car rtlfile)))
 120           (delete-file rtlfile)
 121           (while (re-search-forward ";; Function \\|(call_insn " nil t)
 122             (if (= (char-after (- (point) 3)) ?o)
 123                 (progn
 124                   (looking-at "[a-zA-Z0-9_]+")
 125                   (setq name (intern (match-string 0)))
 126                   (message "%s : %s" (car files) name)
 127                   (setq entry (list name)
 128                         find-gc-subrs-called
 129                         (cons entry find-gc-subrs-called)))
 130               (if (looking-at ".*\n?.*\"\\([A-Za-z0-9_]+\\)\"")
 131                   (progn
 132                     (setq name (intern (match-string 1)))
 133                     (or (memq name (cdr entry))
 134                         (setcdr entry (cons name (cdr entry)))))))))))))
 135
 136 (defun trace-use-tree ()
 137   (setq find-gc-subrs-callers (mapcar 'list (mapcar 'car find-gc-subrs-called)))
 138   (let ((ptr find-gc-subrs-called)
 139         p2 found)
 140     (while ptr
 141       (setq p2 (car ptr))
 142       (while (setq p2 (cdr p2))
 143         (if (setq found (assq (car p2) find-gc-subrs-callers))
 144             (setcdr found (cons (car (car ptr)) (cdr found)))))
 145       (setq ptr (cdr ptr)))))
 146
 147 (provide 'find-gc)
 148
 149 ;;; find-gc.el ends here