2 files changed, 33 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 77fd6cf0fd4..35c81a87ac9 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2009-03-17  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * dired.c (file_name_completion): Check completion-ignored-extensions
+        only if the entry can't affect bestmatch anyway.
+        Stop the search early, as Ftry_completion already does.
+
 2009-03-17  Chong Yidong  <cyd@stupidchicken.com>
 
         * minibuf.c (Vminibuffer_completion_confirm): Doc fix.
diff --git a/src/dired.c b/src/dired.c
index 0779fcd3c89..b6bc7067736 100644
--- a/src/dired.c
+++ b/src/dired.c
@@ -537,6 +537,18 @@ file_name_completion (file, dirname, all_flag, ver_flag, predicate)
       if (!all_flag)
         {
           int skip;
+
+          /* If this entry matches the current bestmatch, the only
+             thing it can do is increase matchcount, so don't bother
+             investigating it any further.  */
+          if (!completion_ignore_case
+              /* The return result depends on whether it's the sole match.  */
+              && matchcount > 1
+              && !includeall /* This match may allow includeall to 0.  */
+              && len >= bestmatchsize
+              && 0 > scmp (dp->d_name, SDATA (bestmatch), bestmatchsize))
+            continue;
+
           if (directoryp)
             {
 #ifndef TRIVIAL_DIRECTORY_ENTRY
@@ -705,8 +717,7 @@ file_name_completion (file, dirname, all_flag, ver_flag, predicate)
               /* This tests that the current file is an exact match
                  but BESTMATCH is not (it is too long).  */
               if ((matchsize == SCHARS (name)
-                   && matchsize + !!directoryp
-                   < SCHARS (bestmatch))
+                   && matchsize + !!directoryp < SCHARS (bestmatch))
                   ||
                   /* If there is no exact match ignoring case,
                      prefer a match that does not change the case
@@ -734,6 +745,20 @@ file_name_completion (file, dirname, all_flag, ver_flag, predicate)
                 bestmatch = name;
             }
           bestmatchsize = matchsize;
+
+          /* If the best completion so far is reduced to the string
+             we're trying to complete, then we already know there's no
+             other completion, so there's no point looking any further.  */
+          if (matchsize <= SCHARS (file)
+              && !includeall /* A future match may allow includeall to 0.  */
+              /* If completion-ignore-case is non-nil, don't
+                 short-circuit because we want to find the best
+                 possible match *including* case differences.  */
+              && (!completion_ignore_case || matchsize == 0)
+              /* The return value depends on whether it's the sole match.  */
+              && matchcount > 1)
+            break;
+
         }
     }