[HLSL][SPIR-V] Add hlsl_private address space for SPIR-V (#133464)
This is an alternative to
https://github.com/llvm/llvm-project/pull/122103
In SPIR-V, private global variables have the Private storage class. This
PR adds a new address space which allows frontend to emit variable with
this storage class when targeting this backend.
This is covered in this proposal: llvm/wg-hlsl@4c9e11a
This PR will cause addrspacecast to show up in several cases, like class
member functions or assignment. Those will have to be handled in the
backend later on, particularly to fixup pointer storage classes in some
functions.
Before this change, global variable were emitted with the 'Function'
storage class, which was wrong.
llvm-project
a625bc60 - [HLSL][SPIR-V] Add hlsl_private address space for SPIR-V (#133464)
