updated for version 7.4.497
Problem: With some regexp patterns the NFA engine uses many states and
becomes very slow. To the user it looks like Vim freezes.
Solution: When the number of states reaches a limit fall back to the old
engine. (Christian Brabandt)
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index b50711c..534ef44 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -5626,6 +5626,10 @@
Note that when using the NFA engine and the pattern contains something
that is not supported the pattern will not match. This is only useful
for debugging the regexp engine.
+ Using automatic selection enables Vim to switch the engine, if the
+ default engine becomes too costly. E.g., when the NFA engine uses too
+ many states. This should prevent Vim from hanging on a combination of
+ a complex pattern with long text.
*'relativenumber'* *'rnu'* *'norelativenumber'* *'nornu'*
'relativenumber' 'rnu' boolean (default off)