[llvm] InlineCost: Use index sizes rather than pointer sizes in a few cases. (PR #119326)

[Alexander Richardson via llvm-commits]

https://github.com/arichardson commented:

The first two are clearly correct and probably fine without a test. The ptrtoint and introptr ones might not be correct for all architectures? E.g. amdgpu fat pointers with 48 (or is it 64?) address bits but only 32 index bits.

https://github.com/llvm/llvm-project/pull/119326