diff -r 87882c8753d4 -r 8d08a28aa63e mercurial/match.py
--- a/mercurial/match.py	Thu Jun 07 01:42:50 2012 +0200
+++ b/mercurial/match.py	Fri Jun 01 15:26:20 2012 -0700
@@ -9,6 +9,14 @@
 import scmutil, util, fileset
 from i18n import _
 
+def _rematcher(pat):
+    m = util.compilere(pat)
+    try:
+        # slightly faster, provided by facebook's re2 bindings
+        return m.test_match
+    except AttributeError:
+        return m.match
+
 def _expandsets(pats, ctx):
     '''convert set: patterns into a list of files in the given context'''
     fset = set()
@@ -280,7 +288,7 @@
         pat = '(?:%s)' % '|'.join([_regex(k, p, tail) for (k, p) in pats])
         if len(pat) > 20000:
             raise OverflowError
-        return pat, re.compile(pat).match
+        return pat, _rematcher(pat)
     except OverflowError:
         # We're using a Python with a tiny regex engine and we
         # made it explode, so we'll divide the pattern list in two
@@ -294,7 +302,7 @@
     except re.error:
         for k, p in pats:
             try:
-                re.compile('(?:%s)' % _regex(k, p, tail))
+                _rematcher('(?:%s)' % _regex(k, p, tail))
             except re.error:
                 raise util.Abort(_("invalid pattern (%s): %s") % (k, p))
         raise util.Abort(_("invalid pattern"))