[PATCH] Speed up backreferences

[Isamu Hasegawa]

From: "Bonzini" <bonzini@gnu.org>

> I profiled factor.sed with cachegrind.  Cache utilization is very good,
> showing practically no misses.  Time is spent 99.99% in sift_states_bkref,
	[snip]
> The patches pass the testsuite in GNU sed will-be-4.0 and 3.9x.  They both
> apply on CVS regex, the 25% patch not requiring the 20% one to have been
> applied previously.

Thank you very much for your work and advice!
I want to fix also the inefficient algorithm.
However, your work is very useful anyway.

Thanks,
-- 
Isamu Hasegawa
IBM Japan, Ltd.