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Date: Thu, 11 Sep 2014 21:00:17 +0200
From: magnum <>
Subject: Re: nVidia Maxwell support (especially descrypt)?

On 2014-09-11 10:39, Solar Designer wrote:
> On Thu, Sep 11, 2014 at 09:54:39AM +0200, magnum wrote:
>> BTW I just dropped the DEScrypt-opencl format to the broken/
>> subdirectory because it keeps giving me problems.
> Ouch.  It worked for me before.

AMD driver (even the one on Super) spews a screenful of complaints about 
the goto's ("warning: goto statement may cause irreducible control 
flow"), and latest stable (as well as 14.4 iirc) finally fails building 
because of just that.

> I'd say it's a compiler problem, but yes we may have to workaround it by
> stopping to use goto, even though this kernel's uses of goto are
> reasonable.  Code size might increase if we express the same things with
> structured programming constructs, and thus speed might be lower.

Perhaps it also might be faster? Like you said in the other post, GPU's 
are weird.

> Those goto's are not data-dependent (they depend on the current
> iteration number only, which is the same for all work-items), so they are
> OK for GPUs' hardware.

Even if that is true we're facing a reality of poor compliers.

 >> To use it, simply move the files back from src/broken to src,
 >> reconfigure and re-build. I hope Sayantan will fix it (as well as the
 >> memory leak discussed before) at some point in time.

It now hit me we could put it back in the tree but add it as a "disabled 
format" in default john.conf instead. That way, enabling it is a soft 
change. Also, the format is actually there if you spell it out with 
"-format:descrypt-opencl", but only then. That's much better, I'll do 
this change now.


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