--- a/src/hotspot/share/opto/machnode.hpp	Tue Oct 08 15:30:46 2019 +0200
+++ b/src/hotspot/share/opto/machnode.hpp	Wed Oct 09 12:30:06 2019 +0000
@@ -197,7 +197,7 @@
 // ADLC inherit from this class.
 class MachNode : public Node {
 public:
-  MachNode() : Node((uint)0), _num_opnds(0), _opnds(NULL) {
+  MachNode() : Node((uint)0), _barrier(0), _num_opnds(0), _opnds(NULL) {
     init_class_id(Class_Mach);
   }
   // Required boilerplate
@@ -211,6 +211,9 @@
   // no constant base node input.
   virtual uint mach_constant_base_node_input() const { return (uint)-1; }
 
+  uint8_t barrier_data() const { return _barrier; }
+  void set_barrier_data(uint data) { _barrier = data; }
+
   // Copy inputs and operands to new node of instruction.
   // Called from cisc_version() and short_branch_version().
   // !!!! The method's body is defined in ad_<arch>.cpp file.
@@ -255,6 +258,9 @@
   // output have choices - but they must use the same choice.
   virtual uint two_adr( ) const { return 0; }
 
+  // The GC might require some barrier metadata for machine code emission.
+  uint8_t _barrier;
+
   // Array of complex operand pointers.  Each corresponds to zero or
   // more leafs.  Must be set by MachNode constructor to point to an
   // internal array of MachOpers.  The MachOper array is sized by