The simpler patch =====================================================

2002-10-22  Paolo Bonzini  (bonzini@gnu.org)

	* posix/regexec.c (sift_states_bkref): bail out
	of the innermost loop as soon as possible.

--- save/regexec.c	Tue Oct 22 22:35:32 2002
+++ ./regexec.c	Tue Oct 22 22:36:43 2002
@@ -1927,15 +1927,18 @@ sift_states_bkref (preg, mctx, sctx, str
               int disabled_idx, subexp_len, to_idx, dst_node;
               struct re_backref_cache_entry *entry;
               entry = mctx->bkref_ents + enabled_idx;
+              if (entry->node != node || entry->str_idx != str_idx)
+		continue;
+
               subexp_len = entry->subexp_to - entry->subexp_from;
               to_idx = str_idx + subexp_len;
+              if (to_idx > sctx->last_str_idx
+                  || sctx->sifted_states[to_idx] == NULL)
+                continue;
+
               dst_node = (subexp_len ? dfa->nexts[node]
                           : dfa->edests[node].elems[0]);
 
-              if (entry->node != node || entry->str_idx != str_idx
-                  || to_idx > sctx->last_str_idx
-                  || sctx->sifted_states[to_idx] == NULL)
-                continue;
               if (!STATE_NODE_CONTAINS (sctx->sifted_states[to_idx], dst_node))
                 continue;