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

[Chris B 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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llvm-beanz wrote:

The intrinsic call getters seems to be a pattern that may grow a lot, and if many of them are going to be followed by EmitRuntimeCall, maybe we could add a `emitConvergentIntrinsic` method to make it more general?

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