[clang] [HLSL] Rewrite semantics parsing (PR #152537)

[Nathan Gauër via cfe-commits]

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@@ -4943,13 +4932,35 @@ def HLSLResourceBinding: InheritableAttr {
   }];
 }
 
-def HLSLSV_Position : HLSLAnnotationAttr {
-  let Spellings = [HLSLAnnotation<"sv_position">];
-  let Subjects = SubjectList<[ParmVar, Field]>;
+def HLSLUnparsedSemantic : HLSLAnnotationAttr {
+  let Spellings = [];
+  let Args = [DefaultIntArgument<"Index", 0>,
+              DefaultBoolArgument<"ExplicitIndex", 0>];
+  let Subjects = SubjectList<[ParmVar, Field, Function]>;
   let LangOpts = [HLSL];
+  let Documentation = [InternalOnly];
+}
+
+def HLSLSV_Position : HLSLSemanticAttr</* Indexable= */ 1> {
   let Documentation = [HLSLSV_PositionDocs];
 }
 
+def HLSLSV_GroupThreadID : HLSLSemanticAttr</* Indexable= */ 0> {
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Keenuts wrote:

Doing this might not be a complete benefit as we'd lose the ability to put some constraints in the TD file (like `Indexable` here).

Created https://github.com/llvm/llvm-project/issues/157659 to track this

https://github.com/llvm/llvm-project/pull/152537