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

[Deric Cheung via cfe-commits]

================
@@ -10623,7 +10623,7 @@ def err_second_argument_to_cwsc_not_pointer : Error<
   "second argument to __builtin_call_with_static_chain must be of pointer type">;
 
 def err_vector_incorrect_num_elements : Error<
-  "%select{too many|too few}0 elements in vector %select{initialization|operand}3 (expected %1 elements, have %2)">;
+  "%select{too many|too few|incorrect number of}0 elements in vector %select{initialization|operand}3 (expected %1 elements, have %2)">;
----------------
Icohedron wrote:

I would still need this change for the other error message when a uint3 is passed.
We don't know if the programmer intended to use the uint2 or the uint4 version of the function, so uint3 has neither more or less elements than expected -- it's just an incorrect number.

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