Fix a cacheing bug, which led to inordinately slow c-beginning-of-defun.

* lisp/progmodes/cc-defs.el (c-self-bind-state-cache): New macro.

* lisp/progmodes/cc-engine.el (c-ssb-lit-begin): Always call c-parse-state
rather than just using the cache variable c-state-cache.
(c-syntactic-skip-backward): Invoke c-self-bind-state-cache to isolate calls
to c-parse-state from other uses of the parse state cache.

* lisp/progmodes/cc-cmds.el (c-beginning-of-defun, c-end-of-defun): Invoke
c-self-bind-state-cache around the processing, replacing flawed bindings of
c-state-cache.

3 files changed, 246 insertions, 222 deletions

diff --git a/lisp/progmodes/cc-cmds.el b/lisp/progmodes/cc-cmds.el
index 6761de11700..764f44a8dd8 100644
--- a/lisp/progmodes/cc-cmds.el
+++ b/lisp/progmodes/cc-cmds.el
@@ -1594,69 +1594,70 @@ defun."
       (c-region-is-active-p)
       (push-mark))
 
-  (c-save-buffer-state
-      (beginning-of-defun-function end-of-defun-function
-       (start (point))
-       (paren-state (copy-tree (c-parse-state))) ; This must not share list
-                                        ; structure with other users of c-state-cache.
-       (orig-point-min (point-min)) (orig-point-max (point-max))
-       lim                          ; Position of { which has been widened to.
-       where pos case-fold-search)
-
-    (save-restriction
-      (if (eq c-defun-tactic 'go-outward)
-          (setq lim (c-widen-to-enclosing-decl-scope ; e.g. class, namespace.
-                     paren-state orig-point-min orig-point-max)))
-
-      ;; Move back out of any macro/comment/string we happen to be in.
-      (c-beginning-of-macro)
-      (setq pos (c-literal-limits))
-      (if pos (goto-char (car pos)))
-
-      (setq where (c-where-wrt-brace-construct))
-
-      (if (< arg 0)
-          ;; Move forward to the closing brace of a function.
-          (progn
-            (if (memq where '(at-function-end outwith-function))
-                (setq arg (1+ arg)))
-            (if (< arg 0)
-                (c-while-widening-to-decl-block
-                 (< (setq arg (- (c-forward-to-nth-EOF-} (- arg) where))) 0)))
-            ;; Move forward to the next opening brace....
-            (when (and (= arg 0)
-                       (progn
-                         (c-while-widening-to-decl-block
-                          (not (c-syntactic-re-search-forward "{" nil 'eob)))
-                         (eq (char-before) ?{)))
-              (backward-char)
-              ;; ... and backward to the function header.
-              (c-beginning-of-decl-1)
-              t))
-
-        ;; Move backward to the opening brace of a function, making successively
-        ;; larger portions of the buffer visible as necessary.
-        (when (> arg 0)
-          (c-while-widening-to-decl-block
-           (> (setq arg (c-backward-to-nth-BOF-{ arg where)) 0)))
-
-        (when (eq arg 0)
-          ;; Go backward to this function's header.
-          (c-beginning-of-decl-1)
-
-          (setq pos (point))
-          ;; We're now there, modulo comments and whitespace.
-          ;; Try to be line oriented; position point at the closest
-          ;; preceding boi that isn't inside a comment, but if we hit
-          ;; the previous declaration then we use the current point
-          ;; instead.
-          (while (and (/= (point) (c-point 'boi))
-                      (c-backward-single-comment)))
-          (if (/= (point) (c-point 'boi))
-              (goto-char pos)))
-
-        (c-keep-region-active)
-        (= arg 0)))))
+  (c-self-bind-state-cache ; We must not share with other users of c-state-cache.
+   (c-save-buffer-state
+       (beginning-of-defun-function
+        end-of-defun-function
+        (start (point))
+        (paren-state (c-parse-state))
+        (orig-point-min (point-min)) (orig-point-max (point-max))
+        lim                 ; Position of { which has been widened to.
+        where pos case-fold-search)
+
+     (save-restriction
+       (if (eq c-defun-tactic 'go-outward)
+           (setq lim (c-widen-to-enclosing-decl-scope ; e.g. class, namespace.
+                      paren-state orig-point-min orig-point-max)))
+
+       ;; Move back out of any macro/comment/string we happen to be in.
+       (c-beginning-of-macro)
+       (setq pos (c-literal-limits))
+       (if pos (goto-char (car pos)))
+
+       (setq where (c-where-wrt-brace-construct))
+
+       (if (< arg 0)
+           ;; Move forward to the closing brace of a function.
+           (progn
+             (if (memq where '(at-function-end outwith-function))
+                 (setq arg (1+ arg)))
+             (if (< arg 0)
+                 (c-while-widening-to-decl-block
+                  (< (setq arg (- (c-forward-to-nth-EOF-} (- arg) where))) 0)))
+             ;; Move forward to the next opening brace....
+             (when (and (= arg 0)
+                        (progn
+                          (c-while-widening-to-decl-block
+                           (not (c-syntactic-re-search-forward "{" nil 'eob)))
+                          (eq (char-before) ?{)))
+               (backward-char)
+               ;; ... and backward to the function header.
+               (c-beginning-of-decl-1)
+               t))
+
+         ;; Move backward to the opening brace of a function, making successively
+         ;; larger portions of the buffer visible as necessary.
+         (when (> arg 0)
+           (c-while-widening-to-decl-block
+            (> (setq arg (c-backward-to-nth-BOF-{ arg where)) 0)))
+
+         (when (eq arg 0)
+           ;; Go backward to this function's header.
+           (c-beginning-of-decl-1)
+
+           (setq pos (point))
+           ;; We're now there, modulo comments and whitespace.
+           ;; Try to be line oriented; position point at the closest
+           ;; preceding boi that isn't inside a comment, but if we hit
+           ;; the previous declaration then we use the current point
+           ;; instead.
+           (while (and (/= (point) (c-point 'boi))
+                       (c-backward-single-comment)))
+           (if (/= (point) (c-point 'boi))
+               (goto-char pos)))
+
+         (c-keep-region-active)
+         (= arg 0))))))
 
 (defun c-forward-to-nth-EOF-} (n where)
   ;; Skip to the closing brace of the Nth function after point.  If
@@ -1718,66 +1719,68 @@ the open-parenthesis that starts a defun; see `beginning-of-defun'."
       (c-region-is-active-p)
       (push-mark))
 
-  (c-save-buffer-state
-      (beginning-of-defun-function end-of-defun-function
-       (start (point))
-       (paren-state (copy-tree (c-parse-state))) ; This must not share list
-                                  ; structure with other users of c-state-cache.
-       (orig-point-min (point-min)) (orig-point-max (point-max))
-       lim
-       where pos case-fold-search)
-
-    (save-restriction
-      (if (eq c-defun-tactic 'go-outward)
-          (setq lim (c-widen-to-enclosing-decl-scope ; e.g. class, namespace
-                     paren-state orig-point-min orig-point-max)))
-
-      ;; Move back out of any macro/comment/string we happen to be in.
-      (c-beginning-of-macro)
-      (setq pos (c-literal-limits))
-      (if pos (goto-char (car pos)))
-
-      (setq where (c-where-wrt-brace-construct))
+  (c-self-bind-state-cache ; c-state-cache's list structure must not be shared
+                           ; with other users.
+   (c-save-buffer-state
+       (beginning-of-defun-function
+        end-of-defun-function
+        (start (point))
+        (paren-state (c-parse-state))
+        (orig-point-min (point-min)) (orig-point-max (point-max))
+        lim
+        where pos case-fold-search)
+
+     (save-restriction
+       (if (eq c-defun-tactic 'go-outward)
+           (setq lim (c-widen-to-enclosing-decl-scope ; e.g. class, namespace
+                      paren-state orig-point-min orig-point-max)))
+
+       ;; Move back out of any macro/comment/string we happen to be in.
+       (c-beginning-of-macro)
+       (setq pos (c-literal-limits))
+       (if pos (goto-char (car pos)))
+
+       (setq where (c-where-wrt-brace-construct))
+
+       (if (< arg 0)
+           ;; Move backwards to the } of a function
+           (progn
+             (if (memq where '(at-header outwith-function))
+                 (setq arg (1+ arg)))
+             (if (< arg 0)
+                 (c-while-widening-to-decl-block
+                  (< (setq arg (- (c-backward-to-nth-BOF-{ (- arg) where))) 0)))
+             (if (= arg 0)
+                 (c-while-widening-to-decl-block
+                  (progn (c-syntactic-skip-backward "^}")
+                         (not (eq (char-before) ?}))))))
+
+         ;; Move forward to the } of a function
+         (if (> arg 0)
+             (c-while-widening-to-decl-block
+              (> (setq arg (c-forward-to-nth-EOF-} arg where)) 0))))
+
+       ;; Do we need to move forward from the brace to the semicolon?
+       (when (eq arg 0)
+         (if (c-in-function-trailer-p)  ; after "}" of struct/enum, etc.
+             (c-syntactic-re-search-forward ";"))
 
-      (if (< arg 0)
-          ;; Move backwards to the } of a function
-          (progn
-            (if (memq where '(at-header outwith-function))
-                (setq arg (1+ arg)))
-            (if (< arg 0)
-                (c-while-widening-to-decl-block
-                 (< (setq arg (- (c-backward-to-nth-BOF-{ (- arg) where))) 0)))
-            (if (= arg 0)
-                (c-while-widening-to-decl-block
-                 (progn (c-syntactic-skip-backward "^}")
-                        (not (eq (char-before) ?}))))))
-
-        ;; Move forward to the } of a function
-        (if (> arg 0)
-            (c-while-widening-to-decl-block
-             (> (setq arg (c-forward-to-nth-EOF-} arg where)) 0))))
-
-      ;; Do we need to move forward from the brace to the semicolon?
-      (when (eq arg 0)
-        (if (c-in-function-trailer-p) ; after "}" of struct/enum, etc.
-            (c-syntactic-re-search-forward ";"))
+         (setq pos (point))
+         ;; We're there now, modulo comments and whitespace.
+         ;; Try to be line oriented; position point after the next
+         ;; newline that isn't inside a comment, but if we hit the
+         ;; next declaration then we use the current point instead.
+         (while (and (not (bolp))
+                     (not (looking-at "\\s *$"))
+                     (c-forward-single-comment)))
+         (cond ((bolp))
+               ((looking-at "\\s *$")
+                (forward-line 1))
+               (t
+                (goto-char pos))))
 
-        (setq pos (point))
-        ;; We're there now, modulo comments and whitespace.
-        ;; Try to be line oriented; position point after the next
-        ;; newline that isn't inside a comment, but if we hit the
-        ;; next declaration then we use the current point instead.
-        (while (and (not (bolp))
-                    (not (looking-at "\\s *$"))
-                    (c-forward-single-comment)))
-        (cond ((bolp))
-              ((looking-at "\\s *$")
-               (forward-line 1))
-              (t
-               (goto-char pos))))
-
-      (c-keep-region-active)
-      (= arg 0))))
+       (c-keep-region-active)
+       (= arg 0)))))
 
 (defun c-defun-name ()
   "Return the name of the current defun, or NIL if there isn't one.
diff --git a/lisp/progmodes/cc-defs.el b/lisp/progmodes/cc-defs.el
index 000995c5b53..3b9f44e55a0 100644
--- a/lisp/progmodes/cc-defs.el
+++ b/lisp/progmodes/cc-defs.el
@@ -1258,7 +1258,8 @@ been put there by c-put-char-property.  POINT remains unchanged."
 (def-edebug-spec c-clear-char-property t)
 (def-edebug-spec c-clear-char-properties t)
 (def-edebug-spec c-put-overlay t)
-(def-edebug-spec c-delete-overlay t) ;))
+(def-edebug-spec c-delete-overlay t)
+(def-edebug-spec c-self-bind-state-cache t);))
 
 
 ;;; Functions.
@@ -1397,6 +1398,26 @@ been put there by c-put-char-property.  POINT remains unchanged."
        (save-restriction
          (widen)
          (c-set-cpp-delimiters ,beg ,end)))))
+
+(defmacro c-self-bind-state-cache (&rest forms)
+  ;; Bind the state cache to itself and execute the FORMS.  It is assumed that no
+  ;; buffer changes will happen in FORMS, and no hidden buffer changes which could
+  ;; affect the parsing will be made by FORMS.
+  `(let ((c-state-cache (copy-tree c-state-cache))
+         (c-state-cache-good-pos c-state-cache-good-pos)
+         ;(c-state-nonlit-pos-cache (copy-tree c-state-nonlit-pos-cache))
+         ;(c-state-nonlit-pos-cache-limit c-state-nonlit-pos-cache-limit)
+         ;(c-state-semi-nonlit-pos-cache (copy-treec c-state-semi-nonlit-pos-cache))
+         ;(c-state-semi-nonlit-pos-cache-limit c-state-semi-nonlit-pos-cache)
+         (c-state-brace-pair-desert (copy-tree c-state-brace-pair-desert))
+         (c-state-point-min c-state-point-min)
+         (c-state-point-min-lit-type c-state-point-min-lit-type)
+         (c-state-point-min-lit-start c-state-point-min-lit-start)
+         (c-state-min-scan-pos c-state-min-scan-pos)
+         (c-state-old-cpp-beg c-state-old-cpp-beg)
+         (c-state-old-cpp-end c-state-old-cpp-end))
+     ,@forms))
+
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; The following macros are to be used only in `c-parse-state' and its
diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 69a2a53d5c9..afe87c5ee6a 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -4259,8 +4259,7 @@ comment at the start of cc-engine.el for more info."
         (setq safe-pos-list (cdr safe-pos-list)))
       (unless (setq safe-pos (car-safe safe-pos-list))
         (setq safe-pos (max (or (c-safe-position
-                                 (point) (or c-state-cache
-                                             (c-parse-state)))
+                                 (point) (c-parse-state))
                                 0)
                             (point-min))
               safe-pos-list (list safe-pos)))
@@ -4308,107 +4307,108 @@ Non-nil is returned if the point moved, nil otherwise.
 Note that this function might do hidden buffer changes.  See the
 comment at the start of cc-engine.el for more info."
 
-  (let ((start (point))
-        state-2
-        ;; A list of syntactically relevant positions in descending
-        ;; order.  It's used to avoid scanning repeatedly over
-        ;; potentially large regions with `parse-partial-sexp' to verify
-        ;; each position.  Used in `c-ssb-lit-begin'
-        safe-pos-list
-        ;; The result from `c-beginning-of-macro' at the start position or the
-        ;; start position itself if it isn't within a macro.  Evaluated on
-        ;; demand.
-        start-macro-beg
-        ;; The earliest position after the current one with the same paren
-        ;; level.  Used only when `paren-level' is set.
-        lit-beg
-        (paren-level-pos (point)))
-
-    (while
-        (progn
-          ;; The next loop "tries" to find the end point each time round,
-          ;; loops when it hasn't succeeded.
-          (while
-              (and
-               (let ((pos (point)))
-                 (while (and
-                         (< (skip-chars-backward skip-chars limit) 0)
-                         ;; Don't stop inside a literal.
-                         (when (setq lit-beg (c-ssb-lit-begin))
-                           (goto-char lit-beg)
-                           t)))
-                 (< (point) pos))
+  (c-self-bind-state-cache
+   (let ((start (point))
+         state-2
+         ;; A list of syntactically relevant positions in descending
+         ;; order.  It's used to avoid scanning repeatedly over
+         ;; potentially large regions with `parse-partial-sexp' to verify
+         ;; each position.  Used in `c-ssb-lit-begin'
+         safe-pos-list
+         ;; The result from `c-beginning-of-macro' at the start position or the
+         ;; start position itself if it isn't within a macro.  Evaluated on
+         ;; demand.
+         start-macro-beg
+         ;; The earliest position after the current one with the same paren
+         ;; level.  Used only when `paren-level' is set.
+         lit-beg
+         (paren-level-pos (point)))
+
+     (while
+         (progn
+           ;; The next loop "tries" to find the end point each time round,
+           ;; loops when it hasn't succeeded.
+           (while
+               (and
+                (let ((pos (point)))
+                  (while (and
+                          (< (skip-chars-backward skip-chars limit) 0)
+                          ;; Don't stop inside a literal.
+                          (when (setq lit-beg (c-ssb-lit-begin))
+                            (goto-char lit-beg)
+                            t)))
+                  (< (point) pos))
+
+                (let ((pos (point)) state-2 pps-end-pos)
 
-               (let ((pos (point)) state-2 pps-end-pos)
+                  (cond
+                   ((and paren-level
+                         (save-excursion
+                           (setq state-2 (parse-partial-sexp
+                                          pos paren-level-pos -1)
+                                 pps-end-pos (point))
+                           (/= (car state-2) 0)))
+                    ;; Not at the right level.
+
+                    (if (and (< (car state-2) 0)
+                             ;; We stop above if we go out of a paren.
+                             ;; Now check whether it precedes or is
+                             ;; nested in the starting sexp.
+                             (save-excursion
+                               (setq state-2
+                                     (parse-partial-sexp
+                                      pps-end-pos paren-level-pos
+                                      nil nil state-2))
+                               (< (car state-2) 0)))
+
+                        ;; We've stopped short of the starting position
+                        ;; so the hit was inside a nested list.  Go up
+                        ;; until we are at the right level.
+                        (condition-case nil
+                            (progn
+                              (goto-char (scan-lists pos -1
+                                                     (- (car state-2))))
+                              (setq paren-level-pos (point))
+                              (if (and limit (>= limit paren-level-pos))
+                                  (progn
+                                    (goto-char limit)
+                                    nil)
+                                t))
+                          (error
+                           (goto-char (or limit (point-min)))
+                           nil))
+
+                      ;; The hit was outside the list at the start
+                      ;; position.  Go to the start of the list and exit.
+                      (goto-char (1+ (elt state-2 1)))
+                      nil))
+
+                   ((c-beginning-of-macro limit)
+                    ;; Inside a macro.
+                    (if (< (point)
+                           (or start-macro-beg
+                               (setq start-macro-beg
+                                     (save-excursion
+                                       (goto-char start)
+                                       (c-beginning-of-macro limit)
+                                       (point)))))
+                        t
+
+                      ;; It's inside the same macro we started in so it's
+                      ;; a relevant match.
+                      (goto-char pos)
+                      nil))))))
 
-                 (cond
-                  ((and paren-level
-                        (save-excursion
-                          (setq state-2 (parse-partial-sexp
-                                         pos paren-level-pos -1)
-                                pps-end-pos (point))
-                          (/= (car state-2) 0)))
-                   ;; Not at the right level.
-
-                   (if (and (< (car state-2) 0)
-                            ;; We stop above if we go out of a paren.
-                            ;; Now check whether it precedes or is
-                            ;; nested in the starting sexp.
-                            (save-excursion
-                              (setq state-2
-                                    (parse-partial-sexp
-                                     pps-end-pos paren-level-pos
-                                     nil nil state-2))
-                              (< (car state-2) 0)))
-
-                       ;; We've stopped short of the starting position
-                       ;; so the hit was inside a nested list.  Go up
-                       ;; until we are at the right level.
-                       (condition-case nil
-                           (progn
-                             (goto-char (scan-lists pos -1
-                                                    (- (car state-2))))
-                             (setq paren-level-pos (point))
-                             (if (and limit (>= limit paren-level-pos))
-                                 (progn
-                                   (goto-char limit)
-                                   nil)
-                               t))
-                         (error
-                          (goto-char (or limit (point-min)))
-                          nil))
-
-                     ;; The hit was outside the list at the start
-                     ;; position.  Go to the start of the list and exit.
-                     (goto-char (1+ (elt state-2 1)))
-                     nil))
-
-                  ((c-beginning-of-macro limit)
-                   ;; Inside a macro.
-                   (if (< (point)
-                          (or start-macro-beg
-                              (setq start-macro-beg
-                                    (save-excursion
-                                      (goto-char start)
-                                      (c-beginning-of-macro limit)
-                                      (point)))))
-                       t
-
-                     ;; It's inside the same macro we started in so it's
-                     ;; a relevant match.
-                     (goto-char pos)
-                     nil))))))
-
-          (> (point)
-             (progn
-               ;; Skip syntactic ws afterwards so that we don't stop at the
-               ;; end of a comment if `skip-chars' is something like "^/".
-               (c-backward-syntactic-ws)
-               (point)))))
+           (> (point)
+              (progn
+                ;; Skip syntactic ws afterwards so that we don't stop at the
+                ;; end of a comment if `skip-chars' is something like "^/".
+                (c-backward-syntactic-ws)
+                (point)))))
 
-    ;; We might want to extend this with more useful return values in
-    ;; the future.
-    (/= (point) start)))
+     ;; We might want to extend this with more useful return values in
+     ;; the future.
+     (/= (point) start))))
 
 ;; The following is an alternative implementation of
 ;; `c-syntactic-skip-backward' that uses backward movement to keep