Re: [Math-atlas-devel] 3DNow! error actually Whaley! error

[Camm M. <ca...@en...>]

Hi Clint!

Great!

R Clint Whaley <rw...@cs...> writes:

> Guys,
> 
> Just found the fix for the error Camm found using 3DNow!.  It happens because
> 3DNow! (like SSE) uses a different loop order than ATLAS's generated kernel.
> In a gemm that handles overlapping operands, I either displayed Enron-like
> judgement in assuming the kernel would always have that loop order (I wrote
> this particular section of code before user-submitted kernels, so this is
> possible), or I just blew a test.  Anyway, this problem can happen on SSE1
> code as well (try "./xsl3blastst -R trmm -m 64 -N 1 64 1" on a PIIISSE1).  I

Confirmed. (i.e. problem exists on sse1, stable)

> am confirming, but I think this can happen in the old stable as well.  The
> only routines where there is any possibility of error are STRMM and STRSM,
> and I can't make STRSM fail yet.
> 

Hoping that this will account for my one known unresolved failure in
the existing stable package, in strsm on m68k.  Details available if
desired. 

> I have updated sourceforge, and I include the 3.3.14 patch below for interested
> parties.  I will confirm on stable and errata as necessary.
> 

Great!


> Cheers,
> Clint
> diff ATLAS/src/blas/gemm GOOD vs BAD:
> 230,231c230
> <          if ( !AC_aliased && lda == NB && K == NB && SCALAR_IS_ONE(alpha) )
> <             pA = (TYPE *) A;
> ---
> >          if ( lda == NB && K == NB && SCALAR_IS_ONE(alpha) ) pA = (TYPE *) A;
> 313,314c312
> <          if (!BC_aliased && ldb == NB && K == NB && alpha == 1.0)
> <             pB = (TYPE *) B;
> ---
> >          if (ldb == NB && K == NB && alpha == 1.0) pB = (TYPE *) B;
> 
> _______________________________________________
> Math-atlas-devel mailing list
> Mat...@li...
> https://lists.sourceforge.net/lists/listinfo/math-atlas-devel
> 
> 

Take care,

-- 
Camm Maguire			     			ca...@en...
==========================================================================
"The earth is but one country, and mankind its citizens."  --  Baha'u'llah