[vsipl++] Atlas patch

[Jules Bergmann]

Stefan Seefeld wrote:
> Assem Salama wrote:
> 
>>> I notice you have taken out this and a couple of other link
>>> generations. What's the rationale
>>> for that ?
>>>   
>> When I tried to do a make, this link produced an error because there
>> already was a lib in vendor/clapack/F2CLIBS/libF77/libF77.a
> 
> Sounds like a bug. I should check whether that file already exists,
> before creating it (or alternatively first removing it).
> But just removing the link generation surely doesn't solve that bug. :-)
> 
>>> Could you summarize / document the build logic a bit ? This last line
>>> actually happens inside the 'ifdef USE_SIMPLE_LAPACK' conditional, so
>>> the following targets are only defined if both variables
>>> (USE_SIMPLE_LAPACK as well
>>> as USE_FORTRAN_LAPACK) are defined. Is that intended ?
>>>   
>> I think you are correct, this is redundant because FORTRAN_LAPACK should
>> never be defined with SIMPLE_LAPACK.
> 
> But can it not be defined (used) without SIMPLE_LAPACK ?
> 
> Thanks,
> 		Stefan
> 

Roughly, we have three configurations for builtin lapack:

  --with-lapack=builtin
    => build ATLAS (provides full CBLAS, partial LAPACK)
    => build ref CLAPACK (provides remainder of LAPACK)
    => build libF77 (provides fortran bits for CLAPACK)

  --with-lapack=fortran-builtin
    => build ATLAS (provides full CBLAS, partial LAPACK)
    => build ref LAPACK (provides remainder of LAPACK)
    (libg2c is required for this approach)

  --with-lapack=simple-builtin
    => build ref CLAPACK/BLAS (provides full BLAS)
    => build ref CLAPACK (provides full LAPACK)
    => build libF77



To avoid duplicating rules in vendor/GNUmakefile.inc.in, let's change 
the logic to be more explicit:

ifdef BUILD_REF_LAPACK
    ... rules to build vendor/lapack/SRC
endif

ifdef BUILD_REF_CLAPACK
    ... rules to build vendor/clapack/SRC
endif

ifdef BUILD_REF_CLAPACK_BLAS
    ... rules to bild vendor/clapack/BLAS/SRC
endif

ifdef BUILD_ATLAS
    rules for vendor/atlas

    if BUILD_REF_LAPACK
       rule to install ATLAS libf77
    endif
endif


ifdef BUILD_LIBF77
    rules to build vendor/clapack/F2CLIBS/libF77
endif


ifdef USE_ATLAS_LAPACK
    rules to merge lapack (either Fortran or C) with atlas
          to generate final lapack
endif

ifdef USE_SIMPLE_LAPACK
    rules to install vendor/clapack/SRC and
                     vendor/clapack/BLAS/SRC
endif




Inside of configure, our options would map to Makefile variables as follows:

  --with-lapack=builtin
     BUILD_ATLAS            = 1
     BUILD_REF_LAPACK       = 0
     BUILD_REF_CLAPACK      = 1
     BUILD_REF_CLAPACK_BLAS = 0
     BUILD_LIBF77           = 1
     USE_ATLAS_LAPACK       = 1
     USE_SIMPLE_LAPACK      = 0

  --with-lapack=fortran-builtin
     BUILD_ATLAS            = 1
     BUILD_REF_LAPACK       = 1
     BUILD_REF_CLAPACK      = 0
     BUILD_REF_CLAPACK_BLAS = 0
     BUILD_LIBF77           = 0
     USE_ATLAS_LAPACK       = 1
     USE_SIMPLE_LAPACK      = 0

  --with-lapack=simple-builtin
     BUILD_ATLAS            = 0
     BUILD_REF_LAPACK       = 0
     BUILD_REF_CLAPACK      = 1
     BUILD_REF_CLAPACK_BLAS = 1
     BUILD_LIBF77           = 1
     USE_ATLAS_LAPACK       = 0
     USE_SIMPLE_LAPACK      = 1

How does this sound?

				-- Jules
-- 
Jules Bergmann
CodeSourcery
jules at codesourcery.com
(650) 331-3385 x705