[llvm] [NVPTX] Add mix precision arith intrinsics (PR #136657)

[Alex MacLean via llvm-commits]

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@@ -1306,6 +1306,48 @@ let TargetPrefix = "nvvm" in {
       DefaultAttrsIntrinsic<[llvm_double_ty], [llvm_double_ty, llvm_double_ty],
         [IntrNoMem, IntrSpeculatable, Commutative]>;
 
+  // Mixed-precision add intrinsics for half and bfloat16 to float
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AlexMaclean wrote:

I think transformations in the backend would be great! My only concern was with adding a new IR representation for something that can already be expressed fairly simply. Adding rules in ISel to handle these cases sounds like a good idea to me. 

https://github.com/llvm/llvm-project/pull/136657