[NFC][DXIL] Add WaveActiveOp dxil operation

    - lowering target for `WaveActive*` ops

Author: inbelic

llvm/lib/Target/DirectX/DXIL.td

@@ -793,6 +793,15 @@ def CreateHandleFromBinding : DXILOp<218, createHandleFromBinding> {
   let stages = [Stages<DXIL1_6, [all_stages]>];
 }
 
+def WaveActiveOp : DXILOp<119, waveActiveOp> {
+  let Doc = "returns the result of the operation across waves";
+  let arguments = [OverloadTy, Int8Ty, Int8Ty];
+  let result = OverloadTy;
+  let overloads = [Overloads<DXIL1_0, [HalfTy, FloatTy, DoubleTy, Int16Ty, Int32Ty, Int64Ty]>];
+  let stages = [Stages<DXIL1_0, [all_stages]>];
+  let attributes = [Attributes<DXIL1_0, [ReadNone]>];
+}
+
 def WaveIsFirstLane :  DXILOp<110, waveIsFirstLane> {
   let Doc = "returns 1 for the first lane in the wave";
   let LLVMIntrinsic = int_dx_wave_is_first_lane;