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

[Rajat Bajpai 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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rajatbajpai wrote:

Yes, they are semantically equivalent. If we are not inclined on adding newer intrinsics, may be we can evaluate adding transformation to xfrm `fpext` + `fadd` => `add.f32.f16` because both the scenarios leads to different SASS. What do you think?

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