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

[Farzon Lotfi via llvm-commits]

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@@ -45,6 +45,14 @@ distance_vec_impl(vector<T, N> X, vector<T, N> Y) {
   return length_vec_impl(X - Y);
 }
 
+constexpr float dot2add_impl(half2 a, half2 b, float c) {
+#if defined(__DIRECTX__)
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farzonl wrote:

Also to answer your question we only need to do one or the other for spirv because the HLSL header is intended to be used with clang and clang will set both defines when some targets spriv.

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