[HLSL] Add resource constructor with implicit binding for global resources (#138976)

Adds constructor for resources with implicit binding and applies it to
all resources without binding at the global scope.
Adds Clang builtin function
`__builtin_hlsl_resource_handlefromimplicitbinding` that gets translated
to `llvm.dx|spv.resource.handlefromimplicitbinding` intrinsic calls.
Specific bindings are assigned in DXILResourceImplicitBinding pass.

Design proposals:

https://github.com/llvm/wg-hlsl/blob/main/proposals/0024-implicit-resource-binding.md

https://github.com/llvm/wg-hlsl/blob/main/proposals/0025-resource-constructors.md

One change from the proposals is that the `orderId` parameter is added
onto the constructor. Originally it was supposed to be generated in
codegen when the `llvm.dx|spv.resource.handlefromimplicitbinding` call
is emitted, but that is not possible because the call is inside a
constructor, and the constructor body is generated once per resource
type and not resource instance. So the only way to inject instance-based
data like `orderId` into the
`llvm.dx|spv.resource.handlefromimplicitbinding` call is that it must
come in via the constructor argument.

Closes #136784

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/Sema/HLSLExternalSemaSource.cpp b/clang/lib/Sema/HLSLExternalSemaSource.cpp
index f09232a..38bde7c 100644
--- a/clang/lib/Sema/HLSLExternalSemaSource.cpp
+++ b/clang/lib/Sema/HLSLExternalSemaSource.cpp
@@ -132,7 +132,8 @@ static BuiltinTypeDeclBuilder setupBufferType(CXXRecordDecl *Decl, Sema &S,
   return BuiltinTypeDeclBuilder(S, Decl)
       .addHandleMember(RC, IsROV, RawBuffer)
       .addDefaultHandleConstructor()
-      .addHandleConstructorFromBinding();
+      .addHandleConstructorFromBinding()
+      .addHandleConstructorFromImplicitBinding();
 }
 
 // This function is responsible for constructing the constraint expression for