I have polished the patch (
     faster code for simple cases of merging 2 or 1 sets,
     fixes of code style, like fancy 2+2 indentation,
     important fix: memory leaks under valgrind - I improperly returned array from a function )

New patch available on URL https://gist.github.com/dobrokot/6337339 and included as attach

 > One thing that'd help would be a test case that illustrates the need for the patch.

Not sure how to properly to send test-case, and how to reference grep compiled old/new binary. I had put it on URL http://dobrokot.ru/dump/slow_dfa_merge.2013-08-26.tar.gz
I can send it in a attach for a "history", if binary/large attaches are allowed in maillists.
Real regex contains sensitive private data, and it's huge. So I had little obfuscated it and reduce to kilobytes. The runtime difference is not so great as in real example (1 to 100), but still large 
( 2-3 times faster ).

Times for new/old version: 2.3sec / 8.7sec

 > I assume you're willing to assign copyright to the FSF for the change?  (I can send you copies of the paperwork, if so.)

You mean, I should somewhere explicitly state, that I am agree with GPL and give FSF rights to distribute and use the code from patch?
If so, I am surely agree with the license, and (proudly) give the permission to use/distribute code from my patch :)

Or you mean some modification of authorship lines in the AUTHORS/THANKS and beginning of dfa.c, which should contain my name now ?

Which paperwork do you mean? Real paper which I should sign with pen and ink?

Thanks for attention, Ivan Yanikov.

On 25.08.2013 11:02, Paul Eggert wrote:
> Ivan Yanikov wrote:
>> How I can properly send/commit it for review?
> You've already done that, sort of, with the pointers
> to the patch.  One thing that'd help would be a test
> case that illustrates the need for the patch.  Also,
> I assume you're willing to assign copyright to the
> FSF for the change?  (I can send you copies of the
> paperwork, if so.)
>