[clang] [HLSL] Support packoffset attribute in AST (PR #89836)

[Chris B via cfe-commits]

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@@ -4372,6 +4372,13 @@ def HLSLResourceBinding: InheritableAttr {
   let Documentation = [HLSLResourceBindingDocs];
 }
 
+def HLSLPackOffset: HLSLAnnotationAttr {
+  let Spellings = [HLSLAnnotation<"packoffset">];
+  let LangOpts = [HLSL];
+  let Args = [IntArgument<"Offset">];
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llvm-beanz wrote:

Looking at this more this seems really weird to me. The argument isn't actually an integer, it's a special string. You're parsing it to an integer, but that actually loses some fidelity.

We should probably store index and sub-component values in the attribute rather than collapsing it down into one value.

https://github.com/llvm/llvm-project/pull/89836