GROMACS

Once we've merged more of the code in Jenkins, I suggest we reorganize some aspects, e.g. within src/gromacs/ewald we have

• pme-gpu-constants.h (plain C, algorithmic constants used across all GPU implementations)
• some kind of header (not yet clear in my mind) that expresses device-specific aspects like warp size needed for derived constants computed below

For each of (solve, gather, spread):

• solve-launch.h (declares high-level functions for kernel launch, preferably C++, but plain C if it has to be)
• solve-common-constants.h (plain C, computes anything specific to this task derived from the above constants)
• solve-constants.cuh, solve-constants.clh (plain C, computes anything specific to this task for this configuration)
• solve-launch.cpp (builds in all three configs, hopefully very low use of preprocessor, includes all the above headers as appropriate)
• solve-kernel.cu, solve-kernel_ocl.clh (only device code, builds in the relevant config, includes the matching solve-constants.*h)
• whatever is necessary to glue the device kernels together in a performant way

This will let us match the tests to the code better, also.

That will leave us with a bunch of high-level workflow and memory-management code in various headers and source files to also reorganize, but grappling with that task will be easier to reason about once we've got the above done.