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

[Ashley Coleman via llvm-commits]

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@@ -19681,6 +19681,21 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
         getDotProductIntrinsic(CGM.getHLSLRuntime(), VecTy0->getElementType()),
         ArrayRef<Value *>{Op0, Op1}, nullptr, "hlsl.dot");
   }
+  case Builtin::BI__builtin_hlsl_dot2add: {
+    llvm::Triple::ArchType Arch = CGM.getTarget().getTriple().getArch();
+    if (Arch != llvm::Triple::dxil) {
+      llvm_unreachable("Intrinsic dot2add can be executed as a builtin only on dxil");
+    }
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V-FEXrt wrote:

also its worth noting that LLVM style says to drop the `{ }` for single line `if/for`

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