OSX blas wrapper for release (Re: plans for release)

[Jarno Rajahalme]

On Feb 3, 2011, at 22:24 , ext John W. Eaton wrote:

> On  3-Feb-2011, Richard Campbell wrote:
> 
> | I'd like to see Jarno's blaswrap.c included in the Octave source, and used
> | automatically when the user runs ./configure for a 64-bit Octave on a 
> machine
> | where the Apple-provided BLAS is the only one detected.
> 
> It would probably be good to also verify that the detected BLAS won't
> work, so that if it is fixed in the future the wrapper won't be
> needed.
> 

After some deliberation I thought the best place for the wrapper is 
libcruft/misc/. This avoids managing an additional dylib, and is a no-op, when 
the wrapper is not needed.

Here is a patch to configure.ac and libcruft/misc/module.mk that:

0) removes -arch flags from FLTK flags to allow compilation with non-Apple GCC
1) if blas is found to be incompatible, tries again with -ff2c
2) if it is still incompatible, and platform is darwin, compiles 
libcruft/misc/blaswrap.c, and tries with that
 - if successful, defines USE_BLASWRAP, so that libcruft will be built to 
contain the wrapper.

Steps to apply:

1. Patch configure.ac and libcruft/misc/module.mk:

$ patch -p 1 < blaswrap.patch

blaswrap.patch
Description: Binary data

The same patch also updates libcruft/misc/module.mk to include blaswrap.c


2. Place blaswrap.c into libcruft/misc

$ cp blaswrap.c /libcruft/misc/.

blaswrap.c
Description: Binary data

blaswrap.c is updated to work from within libcruft (included, save as 
libcruft/misc/blaswrap.c)

The updated wrapper should work also with 32-bit builds. But since the "-ff2c" 
option is tested first, the wrapper will NOT be used on 32-bit builds.


3. Have your config.h.in updated:

$ ./autogen.sh

This works only for the development version. For a snapshot, you need to do 
this manually. Ddd these lines to config.h.in after line 2203:

/* Define this if BLAS functions need to be wrapped (potentially needed for
  OSX only). */
undef USE_BLASWRAP

Please note that if your config.h.in does not get updated (see above), the 
configure will succeed, but the wrapper will be ignored during build, likely 
causing a crash.


4. ./configure <your config options>

Note that there is no need for any blas options here.


5. make -j2 check

If you built on 32-bit OSX, your FFLAGS should now have "-ff2c", and BLAS_LIBS 
should contain "-framework vecLib"

If you built on 64-bit OSX, config.h should define USE_BLASWRAP, and BLAS_LIBS 
should contain "-framework vecLib".

Additionally, after you make octave, you should see that libcruft defines ("T") 
the symbol _cdotu_, while without the wrapper it remains undefined ("U"):

$ nm -g libcruft/.libs/libcruft.dylib | grep -i _cdotu_
00000000000821e0 T _cdotu_
$ 


I have tested this on OSX 10.6.6, with gcc-4.2 and gcc-mp-4.5, building 64-bit 
only. Someone else should test this on a 32-bit build.

NOTE: if you have atlas installed, it will likely be used instead of the 
wrapper. I think this is as it should be.

Finally, as I have never pushed anything on Octave source base, I'd be happy if 
someone else does it.

  Jarno