[llvm-branch-commits] [DirectX] Lower `@llvm.dx.handle.fromBinding` to DXIL ops (PR #104251)

[Justin Bogner via llvm-branch-commits]

https://github.com/bogner created https://github.com/llvm/llvm-project/pull/104251

The `@llvm.dx.handle.fromBinding` intrinsic is lowered either to the
`CreateHandle` op or a pair of `CreateHandleFromBinding` and `AnnotateHandle`
ops, depending on the DXIL version. Regardless of the DXIL version we need to
emit metadata about the binding, but that's left to a separate change.

These DXIL ops all need to return the `%dx.types.Handle` type, but the llvm
intrinsic returns a target extension type. To facilitate changing the type of
the operation and all of its users, we introduce `%llvm.dx.cast.handle`, which
can cast between the two handle representations.