MueLu: Merge *_kokkos factories and their classical counterparts

[cgcgcg]

@trilinos/muelu

Enhancement

We duplicated a lot of algorithms and code paths for use without and with Kokkos. Since MueLu effectively requires Kokkos now, we can start to remove these code duplications. Some removals are quite safe, but others will require a lot of work since the two code branches have diverged significantly.

NOTE: #11682 should be resolved before tackling anything involving coupled aggregation. Removed in #11687

• Remove CMake variables Xpetra_ENABLE_KOKKOS_REFACTOR and MueLu_ENABLE_KOKKOS_REFACTOR Xpetra,MueLu,ShyLU: Drop kokkos refactor #11610
• Merge UtilitiesKokkos into UtilitiesBase and Utilities MueLu: Utilities cleanup #11641
• Aggregates_kokkos MueLu: Merge Aggregates and Aggregates_kokkos #11726
• AggregationPhase1Algorithm_kokkos MueLu: Refactor aggregation #12657
• AggregationPhase2aAlgorithm_kokkos MueLu: Refactor aggregation #12657
• AggregationPhase2bAlgorithm_kokkos MueLu: Refactor aggregation #12657
• AggregationPhase3Algorithm_kokkos MueLu: Refactor aggregation #12657
• AmalgamationFactory_kokkos MueLu: Merge AmalgamationInfo and AmalgamationInfo_kokkos #11719
• MueLu: Merge AmalgamationInfo and AmalgamationInfo_kokkos #11719
• CoalesceDropFactory_kokkos (nightmare?) [DO NOT MERGE] MueLu: Refactor CoalesceDropFactory_kokkos #12861
• CoarseMapFactory_kokkos MueLu: Remove CoarseMapFactory_kokkos #11651
• MueLu: Remove CoordinatesTransferFactory_kokkos #11659
• IsolatedNodeAggregationAlgorithm_kokkos (does not seem to be in use -> delete?) MueLu: Refactor aggregation #12657
• LWGraph_kokkos MueLu: Refactor LWGraphs #12629
• LocalLWGraph_kokkos MueLu: Refactor LWGraphs #12629
• NullspaceFactory_kokkos (only difficulty: move rotations to Kokkos) MueLu: Refactor nullspace factory #12720
• OnePtAggregationAlgorithm_kokkos MueLu: Refactor aggregation #12657
• PreserveDirichletAggregationAlgorithm_kokkos MueLu: Refactor aggregation #12657
• SaPFactory_kokkos MueLu: Refactor SaPFactory #12740
• SemiCoarsenPFactory_kokkos
• TentativePFactory_kokkos
• UncoupledAggregationFactory_kokkos MueLu: Refactor aggregation #12657
• AggregationStructuredAlgorithm_kokkos MueLu: Refactor aggregation #12657
• GeometricInterpolationPFactory_kokkos
• IndexManager_kokkos
• MatrixFreeTentativePFactory_kokkos (rename) MueLu: Rename MatrixFree*_kokkos objects and files #11664
• MatrixFreeTentativeP_kokkos (rename) MueLu: Rename MatrixFree*_kokkos objects and files #11664
• RegionRFactory_kokkos
• StructuredAggregationFactory_kokkos

For cases where the two paths are significantly different, one possible first step is to merge the files and based on the value of use kokkos refactor to take one code path or the other. This would allow to reduce the amount of code duplication. This approach does not work when the factories have outright different inputs and outputs.

The following classes have been merged, but still need to be rewritten to make sure that non-Kokkos and Kokkos code path have the same functionality:

• AggregationPhase1Algorithm
• AggregationPhase2aAlgorithm
• AggregationPhase2bAlgorithm
• AggregationPhase3Algorithm
• OnePtAggregationAlgorithm
• PreserveDirichletAggregationAlgorithm
• SaPFactory - enforcement of constraints

[GrahamBenHarper]

I can rename the matrix-free files since I made them.

[GrahamBenHarper]

Also Aggregates_kokkos should be relatively easy to merge since I think I sync'd up their implemented methods with Aggregates mostly in #10902. The hard part will be merging all the uses of them.

[cgcgcg]

@GrahamBenHarper For Aggregates_kokkos, yes, in principle it could just be a matter of accessing a view instead of a Vector. Are you volunteering?

[GrahamBenHarper]

My schedule's tight right now with a deadline on this coming Tuesday, but after that I should definitely be able to find some time :)

[vbrunini]

We've got a few tests failing in Trilinos integration builds because the factory names are used in XML files and the CoarseMapFactory_kokkos name is no longer recognized. Could we get a deprecation period where both the base factory names and the _kokkos versions are recognized in XML input?

[cgcgcg]

@vbrunini That should be easy to do. I'll get back to you.

[cgcgcg]

@vbrunini Could you let me know if #11770 helped with your integration builds?