[clang] [llvm] [HLSL] Implement dot2add intrinsic (PR #131237)

[Sumit Agarwal via llvm-commits]

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@@ -4894,7 +4894,7 @@ def HLSLDotProduct : LangBuiltin<"HLSL_LANG"> {
 def HLSLDot2Add : LangBuiltin<"HLSL_LANG"> {
   let Spellings = ["__builtin_hlsl_dot2add"];
   let Attributes = [NoThrow, Const, CustomTypeChecking];
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sumitsays wrote:

Removing this makes Codegen unhappy. It is not able to implicitly convert `half` to `_Float16_t`. I think we need to find a way to use `half` here. 

https://github.com/llvm/llvm-project/pull/131237