library name conflicts between BLIS and single-threaded AOCL-BLAS

[smoors]

if you build a single-threaded version of AOCL-BLAS (which is not the default in EasyBuild), library blis.so is created (the multithreaded version is blis-mt.so).

this conflicts with the blis.so lib in BLIS if both AOCL-BLAS and BLIS are (build)dependencies of FlexiBLAS, and the specific library that will be used depends on the ordering of the 2 deps.

we can fix this by adapting both the blis.py and flexiblas.py easyblocks:

• in blis.py:

    def configure_step(self):
        """Custom configopts."""

        self.threading_suffix = ''
        if self.toolchain.options.get('openmp', None):
            self.threading_suffix = '-mt'
            self.cfg.update('configopts', '--enable-threading=openmp')
        ...
    ...

    def build_step(self):

        if self.name == 'AOCL-BLAS':
            self.cfg.update('buildopts', f'LIBBLIS=libaocl-blas{self.threading_suffix}')
            self.cfg.update('buildopts', f'AOCLLIB=aocl-blas{self.threading_suffix}')

        super().build_step()

• in flexiblas.py:

...
            elif blas_lib == 'AOCL_mt':
                configopts[key] = 'aocl-blas-mt'
...

[branfosj]

Does the switching to a CMake FlexiBLAS build help us here?

The example given is with two OpenBLAS versions:

    -DEXTRA="OpenBLAS034;OpenBLAS0310" \
    -DOpenBLAS034_LIBRARY="/home/user/openblas-0.3.4/libopenblas.a;gomp;pthread;" \
    -DOpenBLAS0310_LIBRARY="/home/user/openblas-0.3.10/libopenblas.a;gomp;pthread;"

As this includes the library path we can directly point at both AOCL-BLAS and BLIS.

[smoors]

the example suggests that should work indeed, will try to find some time to test it.

[boegel]

We're only including AOCL-BLAS as dependency since FlexiBLAS 3.4.x, so we can update the FlexiBLAS easyblock to opt-in to using the CMake-based installation procedure for FlexiBLAS >= 3.4 ?

[smoors]

actually, i don't think it will work when multiple BLAS libraries with the same name are loaded, unless RPATH or static linking (as in the example) is used.

[boegel]

@smoors So is it clear how to fix this?

[smoors]

yes, sorry if i wasn't clear.

IMO the best solution is to rename the OACL-BLAS libs to e.g. libaocl-blas.so and libaocl-blas-mt.so (as shown in the code above).

it's not an urgent problem though, because EB by default only builds for OACL-BLAS the multi-threaded libblis-mt.so, not the single-threaded libblis.so (which is the conflicting one).