[clang] [llvm] [HLSL] [DXIL] Implement the `AddUint64` HLSL function and the `UAddc` DXIL op (PR #125319)

[Deric Cheung via cfe-commits]

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@@ -19105,6 +19105,51 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
     return nullptr;
 
   switch (BuiltinID) {
+  case Builtin::BI__builtin_hlsl_adduint64: {
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Icohedron wrote:

Do you think it is something I should do for this implementation?
Are there other HLSL functions that would benefit from / reuse the new builtin using the out args?

https://github.com/llvm/llvm-project/pull/125319