[llvm] Expanding the Histogram Intrinsic (PR #127399)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

What will the strategy to lower those intrinsics? Doe the default lowering need updating?

It would be good to add the intrinsics together with initial lowering as separate patch, including codegen tests.

Then extend LV to use them, which will likely also need updating to the cost model?.

https://github.com/llvm/llvm-project/pull/127399