From: Giuseppe Scrivano <gscrivano@gnu.org>
Date: Sun, 16 Aug 2009 22:15:49 GMT
Subject: Re: Linus' sha1 is much faster!
Message-ID: <87ab1ze76y.fsf@master.homenet>
In-Reply-To: <alpine.LFD.2.01.0908161306340.3162@localhost.localdomain>

Linus Torvalds <torvalds@linux-foundation.org> writes:

> I pretty much can guarantee you that it improves things only because it 
> makes gcc generate crap code, which then hides some of the P4 issues.
>
> I'd also suggest you try gcc-4.4, since that apparently fixes some of the 
> oddest spill issues.


Thanks for the hint.  I tried gcc-4.4 and it produces slower code than
4.3 on the gnulib SHA1 implementation and my patch makes it even more!

I noticed that on my machine your implementation is ~30-40% faster using
SHA_ROT for rol/ror instructions than inline assembly, at least with the
test-case Pádraig wrote.  Am I the only one reporting it?

Cheers,
Giuseppe