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|
;;; find-gc.el --- detect functions that call the garbage collector -*- lexical-binding: t; -*-
;; Copyright (C) 1992, 2001-2023 Free Software Foundation, Inc.
;; Maintainer: emacs-devel@gnu.org
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; Produce in find-gc-unsafe-list the set of all functions that may invoke GC.
;; This expects the Emacs sources to live in find-gc-source-directory.
;;; Code:
(defvar find-gc-unsafe-list nil
"The list of unsafe functions is placed here by `find-gc-unsafe'.")
(defvar find-gc-source-directory
(file-name-as-directory (expand-file-name "src" source-directory))
"Directory containing Emacs C sources.")
(defvar find-gc-subrs-callers nil
"Alist of users of subrs, from GC testing.
Each entry has the form (FUNCTION . FUNCTIONS-THAT-CALL-IT).")
(defvar find-gc-subrs-called nil
"Alist of subrs called, in GC testing.
Each entry has the form (FUNCTION . FUNCTIONS-IT-CALLS).")
;; Functions on this list are safe, even if they appear to be able
;; to call the target.
(defvar find-gc-noreturn-list '(Fsignal Fthrow wrong_type_argument))
;; This was originally generated directory-files, but there were
;; too many files there that were not actually compiled. The
;; list below was created for a HP-UX 7.0 system.
(defvar find-gc-source-files
'("dispnew.c" "scroll.c" "xdisp.c" "window.c"
"term.c" "cm.c" "emacs.c" "keyboard.c" "macros.c"
"keymap.c" "sysdep.c" "buffer.c" "filelock.c"
"insdel.c" "marker.c" "minibuf.c" "fileio.c"
"dired.c" "cmds.c" "casefiddle.c"
"indent.c" "search.c" "regex-emacs.c" "undo.c"
"alloc.c" "data.c" "doc.c" "editfns.c"
"callint.c" "eval.c" "fns.c" "print.c" "lread.c"
"syntax.c" "unexcoff.c"
"bytecode.c" "process.c" "callproc.c" "doprnt.c"
"xterm.c" "xfns.c"))
(defun find-gc-unsafe ()
"Return a list of unsafe functions--that is, which can call GC.
Also store it in `find-gc-unsafe-list'."
(trace-call-tree nil)
(trace-use-tree)
(find-unsafe-funcs 'Fgarbage_collect)
(setq find-gc-unsafe-list
(sort find-gc-unsafe-list
(lambda (x y)
(string-lessp (car x) (car y))))))
;; This does a depth-first search to find all functions that can
;; ultimately call the function "target". The result is an a-list
;; in find-gc-unsafe-list; the cars are the unsafe functions, and the cdrs
;; are (one of) the unsafe functions that these functions directly
;; call.
(defun find-unsafe-funcs (target)
(setq find-gc-unsafe-list (list (list target)))
(trace-unsafe target))
(defun trace-unsafe (func)
(let ((used (assq func find-gc-subrs-callers)))
(or used
(error "No find-gc-subrs-callers for %s" (car find-gc-unsafe-list)))
(while (setq used (cdr used))
(or (assq (car used) find-gc-unsafe-list)
(memq (car used) find-gc-noreturn-list)
(progn
(push (cons (car used) func) find-gc-unsafe-list)
(trace-unsafe (car used)))))))
(defun trace-call-tree (&optional _ignored)
(message "Setting up directories...")
(setq find-gc-subrs-called nil)
(let ((case-fold-search nil)
(default-directory find-gc-source-directory)
(files find-gc-source-files)
name entry rtlfile)
(dolist (file files)
(message "Compiling %s..." file)
(call-process "gcc" nil nil nil "-I" "." "-I" "../lib"
"-fdump-rtl-expand" "-o" null-device "-c" file)
(setq rtlfile
(file-expand-wildcards (format "%s.*.expand" file) t))
(if (/= 1 (length rtlfile))
(message "Error compiling `%s'?" file)
(with-temp-buffer
(insert-file-contents (setq rtlfile (car rtlfile)))
(delete-file rtlfile)
(while (re-search-forward ";; Function \\|(call_insn " nil t)
(if (= (char-after (- (point) 3)) ?o)
(progn
(looking-at "[a-zA-Z0-9_]+")
(setq name (intern (match-string 0)))
(message "%s : %s" (car files) name)
(setq entry (list name)
find-gc-subrs-called
(cons entry find-gc-subrs-called)))
(if (looking-at ".*\n?.*\"\\([A-Za-z0-9_]+\\)\"")
(progn
(setq name (intern (match-string 1)))
(or (memq name (cdr entry))
(setcdr entry (cons name (cdr entry)))))))))))))
(defun trace-use-tree ()
(setq find-gc-subrs-callers
(mapcar #'list (mapcar #'car find-gc-subrs-called)))
(let ((ptr find-gc-subrs-called)
p2 found)
(while ptr
(setq p2 (car ptr))
(while (setq p2 (cdr p2))
(if (setq found (assq (car p2) find-gc-subrs-callers))
(setcdr found (cons (car (car ptr)) (cdr found)))))
(setq ptr (cdr ptr)))))
(provide 'find-gc)
;;; find-gc.el ends here
|
