CC Mode: Remedy recent loss in performance

* lisp/progmodes/cc-engine.el (c-back-over-member-initializers): call
c-parse-state outside of the narrowing operation.

* lisp/progmodes/cc-fonts.el (c-get-fontification-context)
(c-font-lock-cut-off-declarators): Replace calls to c-determine-limit with
crude position calculations for speed.

2 files changed, 11 insertions, 5 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 6598cc62c20..d3d7a1c5c0a 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -8611,10 +8611,11 @@ comment at the start of cc-engine.el for more info."
   ;; the function's arglist.  Otherwise return nil, leaving point unchanged.
   ;; LIMIT, if non-nil, is a limit for the backward search.
   (save-restriction
-    (if limit (narrow-to-region limit (point)))
     (let ((here (point))
-          (paren-state (c-parse-state))
+          (paren-state (c-parse-state)) ; Do this outside the narrowing for
+                                        ; performance reasons.
           pos level-plausible at-top-level res)
+      (if limit (narrow-to-region limit (point)))
       ;; Assume tentatively that we're at the top level.  Try to go back to the
       ;; colon we seek.
       (setq res
@@ -8637,7 +8638,8 @@ comment at the start of cc-engine.el for more info."
 
               (while (and (not (and level-plausible
                                     (setq at-top-level (c-at-toplevel-p))))
-                          (setq pos (c-pull-open-brace paren-state))) ; might be a paren.
+                          (setq pos (c-pull-open-brace paren-state)) ; might be a paren.
+                          (or (null limit) (>= pos limit)))
                 (setq level-plausible
                       (catch 'level
                         (goto-char pos)
diff --git a/lisp/progmodes/cc-fonts.el b/lisp/progmodes/cc-fonts.el
index cef2015f430..269d2c90b79 100644
--- a/lisp/progmodes/cc-fonts.el
+++ b/lisp/progmodes/cc-fonts.el
@@ -1204,7 +1204,9 @@ casts and declarations are fontified.  Used on level 2 and higher."
           ((save-excursion
              (goto-char match-pos)
              (and (memq (char-before match-pos) '(?\( ?\,))
-                  (c-go-up-list-backward match-pos (c-determine-limit 500))
+                  (c-go-up-list-backward match-pos
+                                          ; c-determine-limit is too slow, here.
+                                         (max (- (point) 2000) (point-min)))
                   (eq (char-after) ?\()
                   (let ((type (c-get-char-property (point) 'c-type)))
                     (or (memq type '(c-decl-arg-start c-decl-type-start))
@@ -1605,7 +1607,9 @@ casts and declarations are fontified.  Used on level 2 and higher."
           c-recognize-knr-p)            ; Strictly speaking, bogus, but it
                                         ; speeds up lisp.h tremendously.
       (save-excursion
-        (when (not (c-back-over-member-initializers (c-determine-limit 2000)))
+        (when (not (c-back-over-member-initializers
+                    (max (- (point) 2000) (point-min)))) ; c-determine-limit
+                                                         ; is too slow, here.
           (unless (or (eobp)
                       (looking-at "\\s(\\|\\s)"))
             (forward-char))