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

[John W. Eaton]

On  4-Feb-2011, bpabbott wrote:

| On Feb 04, 2011, at 09:58 AM, Jarno Rajahalme <address@hidden> wrote:
| 
| 
| 
|     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
| 
| 
| 
|     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 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.hin 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
| 
|  
| I've attempted to convert the diffs into changesets. They are attached.
| 
| Jarno/Richard,
| 
| Please try use apply these and confirm they work as intended.
| 
| John,
| 
| I'm skittish about pushing changes to the build process. I'll wait for you to
| approve or to push these yourself.

The patch that adds the blaswrap file looks OK, but it could be merged
with the changes to the configure script since those changes also use
the new blas wrappers.

diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -911,6 +911,12 @@
       *-*-mingw*)
         FLTK_LDFLAGS="`echo $FLTK_LDFLAGS | sed -e 's/-mwindows//g'`"
       ;;
+      *-*-darwin*)
+## -arch XXXX option is not available in GCC 4.5...
+        FLTK_CFLAGS="`echo $FLTK_CFLAGS | sed -e 's/-arch [[^ ]]* //g'`"
+        FLTK_LDFLAGS="`echo $FLTK_LDFLAGS | sed -e 's/-arch [[^ ]]* //g'`"
+      ;;
+

This change looks like it fixes some other problem unrelated to the
BLAS, so I think it should be a separate changeset.  If you are making
a change for a specific version of GCC, then this filtering of FLTK
options should probably not be done for all versions of GCC.
 
     AC_MSG_CHECKING([for OpenGL support in FLTK])
@@ -978,6 +984,56 @@
 ## Restore FFLAGS.
 FFLAGS="$save_FFLAGS"
 
+## On OSX, try again with a wrapper library (without -ff2c!)
+if test "x$ax_blas_f77_func_ok" = "xno"; then
+  case "$canonical_host_type" in
+    *-*-darwin*)
+      ## test if wrapper functions help
+      $CC $CPPFLAGS $CFLAGS -DUSE_BLASWRAP -c -fomit-frame-pointer -W -Wall 
libcruft/misc/blaswrap.c -o conftest_blaswrap.o

Please use autoconf macros to invoke compilers, and don't add random
flags like -fomit-frame-pointer or other warning options.  That way
the options determined earlier in the configure script will be used
consistently.  See the OCTAVE_CHECK_FORTRAN_INTEGER_SIZE macro
definition in acinclude.m4 for an example of using AC_COMPILE_IFELSE
to compile a temporary file.

jwe