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mpimd-csc / flexiblas

FlexiBLAS - A BLAS and LAPACK wrapper library with runtime exchangeable backends. This is only a mirror of https://gitlab.mpi-magdeburg.mpg.de/software/flexiblas-release
https://www.mpi-magdeburg.mpg.de/projects/flexiblas
GNU Lesser General Public License v3.0
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Improving backend auto detection #27

Closed kcgthb closed 2 years ago

kcgthb commented 2 years ago

Hi!

I just spent a few hours trying to understand why my Open BLAS and BLIS installations were not detected by cmake, until I realized that CMake's find_library was explicitly called with NO_CMAKE_PATH NO_CMAKE_ENVIRONMENT_PATH in all the Find<blas_installation>.cmake files. Like in https://github.com/mpimd-csc/flexiblas/blob/bb816067e9900cff14a73489aac1455108ff1d96/cmake/FindBlisSerial.cmake#L14

Is that intentional? What's the rationale behind this?

In a lot of HPC environments, BLAS libs are made available to users through environment modules that set environment variables, and could expose installation paths in things like CMAKE_{PREFIX,INCLUDE,LIBRARY}_PATH.

By artificially limiting the scope of FIND_LIBRARY detection, and limiting it to OS-specific directories , CMake will be able to detect BLAS libraries that have been installed via OS package managers (as RPM or DEBs). But that's rarely the case on large-scale computing systems, where software installations often reside on shared, networked file systems.

Would it be possible to remove that limitation, and let CMake try to autodetect BLAS installations in other directories as well, as specified in CMAKE_*_PATH env variables, without having to manually specify a long list of -DEXTRA entries?

Happy to provide a PR if needed. Thanks!

grisuthedragon commented 2 years ago

The reason, why this was never detected, was that we only test on:

If you have an idea in mind, please provide a PR (only for one Find... file by now) and we discuss a proper solution. Once we have it, we port it to the other Find... scripts. One must have is, that is does not break the detection on Fedora/Ubuntu/Debian. If we make it until end of this week, it will be included in the next release.

kcgthb commented 2 years ago

Thanks @grisuthedragon ! PR proposed in #28 for FindOpenBLASSerial.cmake

grisuthedragon commented 2 years ago

This looks promising. I will integrate the patch for all find routines.

kcgthb commented 2 years ago

Excellent, thank you!

grisuthedragon commented 2 years ago

Closed in 3.2.0