[llvm] [SPIR-V] Add capability for non-uniform indexing for `StructuredBuffer` types. (PR #163424)

[Steven Perron via llvm-commits]

https://github.com/s-perron commented:

I found more bugs in the code in this function. Since we are trying to fix is up, can we get all of it fixed? We need to make sure that the index to the access chain is not a constant. For storage buffers, we need to pick out only the index into the array of storage buffers.

I think we can do that by making sure the input to the AC is a variable in the storage buffer storage class, and the type is an array.

I don't we have to worry about multi dimensional arrays. They are not allowed.

https://github.com/llvm/llvm-project/pull/163424