gotoblas_corename() showing apparently incorrect cpu identification

[danielwe]

My machine has Xeon E7 4870 processors, which use the Nehalem-based Westmere microarchitecture. However, OpenBLAS built with DYNAMIC_ARCH appears to identify them as Atom cores. The output of openblas_get_config() is:

OpenBLAS 0.3.5  USE64BITINT DYNAMIC_ARCH NO_AFFINITY Atom MAX_THREADS=32

export OPENBLAS_CORETYPE=Nehalem makes no difference

I think the actual problem is that with DYNAMIC_ARCH but not DYNAMIC_OLDER, gotoblas_ATOM is aliased to gotoblas_NEHALEM, and gotoblas_coretype() checks for gotoblas == &gotoblas_ATOM before gotoblas == &gotoblas_NEHALEM:
https://github.com/xianyi/OpenBLAS/blob/9d5079008f964d0be08708dc3785ebcf5b7bf68b/driver/others/dynamic.c#L767-L771

Seems like the solution would be one of the following:

• Make sure that the gotoblas_<ARCH> identifiers that could be aliases are checked last in gotoblas_corename(), or
• Disable some of the checks in gotoblas_corename() depending on compiler flags

[martin-frbg]

Option #2 looks cleaner to me (though neither will solve the "problem" with a custom DYNAMIC_LIST - which would require a nasty cascade of ifdefs that is probably not worthwile to implement)