[clang] [HLSL] Avoid putting the byval attribute on out and inout parameters (PR #150495)

[Sarah Spall via cfe-commits]

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@@ -2852,20 +2852,28 @@ void CodeGenModule::ConstructAttributeList(StringRef Name,
       if (AI.getInReg())
         Attrs.addAttribute(llvm::Attribute::InReg);
 
-      // Depending on the ABI, this may be either a byval or a dead_on_return
-      // argument.
-      if (AI.getIndirectByVal()) {
-        Attrs.addByValAttr(getTypes().ConvertTypeForMem(ParamType));
-      } else {
-        // Add dead_on_return when the object's lifetime ends in the callee.
-        // This includes trivially-destructible objects, as well as objects
-        // whose destruction / clean-up is carried out within the callee (e.g.,
-        // Obj-C ARC-managed structs, MSVC callee-destroyed objects).
-        if (!ParamType.isDestructedType() || !ParamType->isRecordType() ||
-            ParamType->castAs<RecordType>()
-                ->getDecl()
-                ->isParamDestroyedInCallee())
-          Attrs.addAttribute(llvm::Attribute::DeadOnReturn);
+      // HLSL out and inout parameters must not be marked with ByVal or
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spall wrote:

Maybe expand this comment to explain why it isn't byval
"HLSL out/inout parameters are not ByVal because the caller is meant to see the callees changes"

https://github.com/llvm/llvm-project/pull/150495