[llvm] [DirectX] Make dx.RawBuffer an op that can't be replaced (PR #154620)

[Farzon Lotfi via llvm-commits]

farzonl wrote:

> > > This looks good to me. Please wait to hear back from @nikic on whether we should do the isTokenLikeTy() refactoring before or after this change.
> > 
> > 
> > I'd like the usages in the IR verifier to be adjusted, and an IR verifier test added that errors when using such a type in a phi node.
> > I don't think we need to replace other uses at this time.
> 
> @bogner can you verify if these are all case we would not want a Raw or Typed Buffer?
> 
> 1. llvm/lib/IR/Verifier.cpp:3009:      Check(!Arg.getType()->isTokenTy(),
> 
> `Function takes token but isn't an intrinsic` example:
> 
> ```
> define void @f(token %A) {
> entry:
>   ret void
> }
> ```
> 
> 2. llvm/lib/IR/Verifier.cpp:3023:    Check(!F.getReturnType()->isTokenTy(),
>    `Function returns a token but isn't an intrinsic`
>    example:
> 
> ```
> define token @f() {
> entry:
>   ret token undef
> }
> ```
> 
> 3. llvm/lib/IR/Verifier.cpp:3637:  Check(!PN.getType()->isTokenTy(), "PHI nodes cannot have token type!");
> 
> Obviously this one is a yes we don't want Raw or Type buffers in PHI nodes
> 
> 4. llvm/lib/IR/Verifier.cpp:3842:      Check(!ParamTy->isTokenTy(),
>    `Function has token parameter but isn't an intrinsic`
> 
> There was no test case for this one.
> 
> 5. llvm/lib/IR/Verifier.cpp:3849:    Check(!FTy->getReturnType()->isTokenTy(),
> 
> `Return type cannot be token for indirect call!` example
> 
> ```
> define void @f() {
> entry:
>   call token () undef ()
>   ret void
> }
> ```

@bogner  the new Verifier changes are causing  `CodeGenHLSL/builtins/hlsl_resource_t.hlsl` to fail 
specifically  with the error:`Function takes token but isn't an intrinsic`


https://github.com/llvm/llvm-project/pull/154620