[Hexagon] Implement @llvm.readcyclecounter()

llvm-svn: 295892
diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.h b/llvm/lib/Target/Hexagon/HexagonISelLowering.h
index 792234b..80add5d 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.h
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.h
@@ -86,6 +86,7 @@
       TC_RETURN,
       EH_RETURN,
       DCFETCH,
+      READCYCLE,
 
       OP_END
     };
@@ -146,6 +147,7 @@
     SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerINLINEASM(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerPREFETCH(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerREADCYCLECOUNTER(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerEH_LABEL(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerEH_RETURN(SDValue Op, SelectionDAG &DAG) const;
     SDValue