[clang] [llvm] [HIP] add --offload-compression-level= option (PR #83605)

[David Blaikie via cfe-commits]

dwblaikie wrote:

> level 20 is a sweet spot for both compression rate and compression time

I wonder how much this is overfitting for kernels of a particular size, though? (is it making the window just large enough that there's some "memory" from one kernel to the next - but a slightly larger kernel would cause it to fail to see the similarities of two or more kernels - and equally, would a lower level have a smaller window which would be adequate for smaller kernels?)

If level does imply window size and that does imply the size of the kernels that can be efficiently compressed across multiple similar copies - it might be interesting to know what range of kernel sizes fit in the new default, and if that size is representative of the majority of kernels.

https://github.com/llvm/llvm-project/pull/83605