[clang] [llvm] [clang][HLSL] Add WaveIsFirstLane() intrinsic (PR #103299)

[Farzon Lotfi via cfe-commits]

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@@ -18660,6 +18660,10 @@ case Builtin::BI__builtin_hlsl_elementwise_isinf: {
         llvm::FunctionType::get(IntTy, {}, false), "__hlsl_wave_get_lane_index",
         {}, false, true));
   }
+  case Builtin::BI__builtin_hlsl_wave_is_first_lane: {
+    Intrinsic::ID ID = CGM.getHLSLRuntime().getWaveIsFirstLaneIntrinsic();
+    return EmitRuntimeCall(Intrinsic::getDeclaration(&CGM.getModule(), ID));
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farzonl wrote:

we typically have used `return Builder.CreateIntrinsic(...);` Whats the reason\advantage to using EmitRuntimeCall?

https://github.com/llvm/llvm-project/pull/103299