[petsc-dev] AVX kernels, old gcc, still broken

[Jed Brown]

"Smith, Barry F." <bsmith at mcs.anl.gov> writes:

>   The proposed fix is #if defined(PETSC_USE_AVX512_KERNELS)   && && && && && in https://gitlab.com/petsc/petsc/merge_requests/2213/diffs

Looks fine; approved.

> but note that PETSC_USE_AVX512_KERNELS does not even do a configure check to make sure it is valid. The user has to guess that passing that flag will work. Of course a proper configure test is needed and since a proper test is needed it can handle all the issues in one place instead of having one issue in  configure and n - 1 in the source code. 

What are "all the issues"?  32-bit indices, precision=double,
scalar=real?  So we'll need 8 CPP macros that test each of those
combinations?

>   This is a basic implementation disagreement, I hate CPP and think it should be used minimally, you hate configure and think it should be used minimally.