I'm happy to announce that I've managed to generate OpenGL compute shaders from the OpenCL compilation pipeline. Through the use of https://github.com/KhronosGroup/SPIRV-Cross the means that we can generate GLSL, HLSL and MSL source

The setup and compilation steps is very janky at the moment but does produce legit looking GLSL/HLSL. I say looks, because I lack the means to run it at the moment. This will hopefully become less janky in the future.

To produce a compute shader source you will need:
ldc built with https://github.com/KhronosGroup/SPIRV-LLVM-Translator as with the regular means of producing OpenCL SPIR-V,
https://github.com/google/clspv/ with https://github.com/google/clspv/pull/764 applied to convert the OpenCL SPIR-V to OpenGL compute SPIR-V and
https://github.com/KhronosGroup/SPIRV-Cross to convert the resulting GL compute SPIR-V to HLSL/MSL if desired.

The full compilation steps are then (I did say it was janky):

ldc2 --mdcompute-targets=ocl-200 -m32 ./kernel.d other_files.d -Iother_imports
llvm-spirv -r kernels_ocl200_32.spv
llvm-dis kernels_ocl200_32.bc
clspv -x=ir kernels_ocl200_32.ll
# and optionally
spirv-cross --hlsl a.spv --output a.hlsl

32-bit mode for ldc is required because only 32-bit OpenCL SPIR-V can be converted into OpenGL compute SPIR-V. If -m32 doesn't work the you may have to supply an equivalent -mtriple