Add Kokos implementation of SWM

[sjsprecious]

This pull request introduces the multiple implementations of Kokkos based SWM (e.g., different policies, Kokkos+OpenACC).

All the CPU and GPU answers are verified against the C serial version.

It also includes some util python scripts for verification check and visualization.

[Copilot]

Pull request overview

This PR adds multiple Kokkos-based implementations of the Shallow Water Model (SWM), including various execution policies (TeamPolicy, RangePolicy, MDRangePolicy) and a hybrid Kokkos+OpenACC+Fortran version. The implementations have been verified against the C serial version for both CPU and GPU execution. Supporting utilities for verification and performance visualization are also included.

Key Changes:

• Implementation of four distinct Kokkos policy variations for performance comparison
• Hybrid Kokkos+Fortran+OpenACC implementation demonstrating interoperability
• Python utilities for result validation and performance plotting
• CMake integration for building Kokkos implementations

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
swm_kokkos/various_policy_impls/shallow_teampolicy.cpp	TeamPolicy-based SWM implementation with hierarchical parallelism
swm_kokkos/various_policy_impls/shallow_rangepolicy_flat.cpp	RangePolicy implementation using flattened index calculations
swm_kokkos/various_policy_impls/shallow_rangepolicy.cpp	RangePolicy implementation with inner serial loops
swm_kokkos/various_policy_impls/shallow_mdrangepolicy.cpp	MDRangePolicy implementation for multi-dimensional parallelism
swm_kokkos/utils/plot.py	Performance visualization script for comparing implementations
swm_kokkos/utils/data/O2/kokkos_teampolicy.csv	Benchmark data for TeamPolicy implementation
swm_kokkos/utils/data/O2/kokkos_rangepolicy.csv	Benchmark data for RangePolicy implementation
swm_kokkos/utils/data/O2/kokkos_mdrangepolicy.csv	Benchmark data for MDRangePolicy implementation
swm_kokkos/utils/comparison_results.sh	Shell script for automated result verification
swm_kokkos/utils/comparison_results.py	Python script for numerical comparison of outputs
swm_kokkos/kokkos_fortran_openacc/shallow_mdrangepolicy.cpp	C++ wrapper for Kokkos+Fortran+OpenACC hybrid implementation
swm_kokkos/kokkos_fortran_openacc/shallow_fortran_acc.F90	Fortran module with OpenACC directives for time loop
swm_kokkos/CMakeLists.txt	Build configuration for Kokkos implementations
CMakeLists.txt	Top-level CMake configuration with SWM_KOKKOS option

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[Copilot]

Hard-coded absolute paths reduce script portability. Consider using relative paths or environment variables to make the script usable across different systems and user configurations.

Suggested change

	path1="/glade/derecho/scratch/sunjian/SWM_KOKKOS_CUDA_BUILD/swm_c/c/"
	path2="/glade/derecho/scratch/sunjian/SWM_KOKKOS_CUDA_BUILD/swm_kokkos/kokkos_fortran_openacc/"
	# Use environment variables SWM_C_PATH and SWM_KOKKOS_PATH if set, otherwise use current directory as default
	path1="${SWM_C_PATH:-./swm_c/c/}"
	path2="${SWM_KOKKOS_PATH:-./swm_kokkos/kokkos_fortran_openacc/}"