This introduces `__builtin_hlsl_resource_getpointer`, which lowers to
`llvm.dx.resource.getpointer` and is used to implement indexing into
resources.
This will only work through the backend for typed buffers at this point,
but the changes to structured buffers should be correct as far as the
frontend is concerned.
Note: We probably want this to return a reference in the HLSL device
address space, but for now we're just using address space 0. Creating a
device address space and updating this code can be done later as
necessary.
Fixes#95956
Adds `RasterizerOrderedStructuredBuffer` definition to
HLSLExternalSemaSource. Adds separate tests for the AST shape and
element types. Adds constructor/handle.fromBinding and subscript test
cases to shared test file for structured buffers. Additional methods
will be added later.
Fixes#112776
Add tests for RWStructuredBuffer class definition. Use shared test files
for all structured buffers' constructor and subscript tests. Keep AST
and element-type tests separate for each buffer type because they longer
and failures would be harder to match.
Fixes#112775
