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Date: Thu, 27 Jun 2013 18:40:33 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: Parallella: bcrypt

Katja,

On Mon, Jun 24, 2013 at 04:54:45PM +0200, Katja Malvoni wrote:
> On Tue, May 28, 2013 at 1:58 AM, Solar Designer <solar@...nwall.com> wrote:
> > On Sun, May 26, 2013 at 07:37:55PM -0400, Yaniv Sapir wrote:
> > > -mfp-mode=int        # this sets the FPU mode to integer. However, please
> > > make sure that the generated code does not re-program the CONFIG register
> > > before every integer operation
> >
> > Let's definitely try this.  I was afraid we'd have to resort to assembly
> > code to use the FPU in integer mode - it's great news to me that we seem
> > not to have to.
> 
> Unfortunately, this doesn't help a lot... Execution speed with -02 is
> 45.969000 ms and with -mfp-mode=int is 45.951000 ms. I checked generated
> assembly code it seems that CONFIG register isn't re-programmed before
> every integer operation.

... but are there uses of the IADD instruction (the one implemented on
the FPU) at all, or only plain ADD (the one implemented on IALU)?

Can you show us a piece of disassembly - e.g., for one Blowfish round?

Thanks,

Alexander

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