--- a/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp	Fri Nov 09 10:38:07 2018 +0100
+++ b/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp	Fri Nov 09 10:38:07 2018 +0100
@@ -288,6 +288,9 @@
 #ifdef ASSERT
   virtual bool verify_gc_alias_type(const TypePtr* adr_type, int offset) const { return false; }
 #endif
+
+  virtual bool final_graph_reshaping(Compile* compile, Node* n, uint opcode) const { return false; }
+
 };
 
 #endif // SHARE_GC_SHARED_C2_BARRIERSETC2_HPP

--- a/src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp	Fri Nov 09 10:38:07 2018 +0100
+++ b/src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp	Fri Nov 09 10:38:07 2018 +0100
@@ -1435,6 +1435,29 @@
   return type == T_OBJECT || type == T_ARRAY;
 }
 
+bool ZBarrierSetC2::final_graph_reshaping(Compile* compile, Node* n, uint opcode) const {
+  bool handled;
+  switch (opcode) {
+    case Op_LoadBarrierSlowReg:
+    case Op_LoadBarrierWeakSlowReg:
+#ifdef ASSERT
+      if (VerifyOptoOopOffsets) {
+        MemNode* mem  = n->as_Mem();
+        // Check to see if address types have grounded out somehow.
+        const TypeInstPtr* tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
+        ciInstanceKlass* k = tp->klass()->as_instance_klass();
+        bool oop_offset_is_sane = k->contains_field_offset(tp->offset());
+        assert(!tp || oop_offset_is_sane, "");
+      }
+#endif
+      handled = true;
+      break;
+    default:
+      handled = false;
+  }
+  return handled;
+}
+
 // == Verification ==
 
 #ifdef ASSERT

--- a/src/hotspot/share/gc/z/c2/zBarrierSetC2.hpp	Fri Nov 09 10:38:07 2018 +0100
+++ b/src/hotspot/share/gc/z/c2/zBarrierSetC2.hpp	Fri Nov 09 10:38:07 2018 +0100
@@ -207,6 +207,8 @@
   static void find_dominating_barriers(PhaseIterGVN& igvn);
   static void loop_optimize_gc_barrier(PhaseIdealLoop* phase, Node* node, bool last_round);
 
+  virtual bool final_graph_reshaping(Compile* compile, Node* n, uint opcode) const;
+
 #ifdef ASSERT
   virtual void verify_gc_barriers(Compile* compile, CompilePhase phase) const;
 #endif

--- a/src/hotspot/share/opto/compile.cpp	Fri Nov 09 10:38:07 2018 +0100
+++ b/src/hotspot/share/opto/compile.cpp	Fri Nov 09 10:38:07 2018 +0100
@@ -2792,6 +2792,18 @@
   }
 #endif
   // Count FPU ops and common calls, implements item (3)
+  bool gc_handled = BarrierSet::barrier_set()->barrier_set_c2()->final_graph_reshaping(this, n, nop);
+  if (!gc_handled) {
+    final_graph_reshaping_main_switch(n, frc, nop);
+  }
+
+  // Collect CFG split points
+  if (n->is_MultiBranch() && !n->is_RangeCheck()) {
+    frc._tests.push(n);
+  }
+}
+
+void Compile::final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& frc, uint nop) {
   switch( nop ) {
   // Count all float operations that may use FPU
   case Op_AddF:
@@ -2938,18 +2950,13 @@
   case Op_LoadL_unaligned:
   case Op_LoadPLocked:
   case Op_LoadP:
-#if INCLUDE_ZGC
-  case Op_LoadBarrierSlowReg:
-  case Op_LoadBarrierWeakSlowReg:
-#endif
   case Op_LoadN:
   case Op_LoadRange:
   case Op_LoadS: {
   handle_mem:
 #ifdef ASSERT
     if( VerifyOptoOopOffsets ) {
-      assert( n->is_Mem(), "" );
-      MemNode *mem  = (MemNode*)n;
+      MemNode* mem  = n->as_Mem();
       // Check to see if address types have grounded out somehow.
       const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
       assert( !tp || oop_offset_is_sane(tp), "" );
@@ -3467,16 +3474,11 @@
     break;
   }
   default:
-    assert( !n->is_Call(), "" );
-    assert( !n->is_Mem(), "" );
-    assert( nop != Op_ProfileBoolean, "should be eliminated during IGVN");
+    assert(!n->is_Call(), "");
+    assert(!n->is_Mem(), "");
+    assert(nop != Op_ProfileBoolean, "should be eliminated during IGVN");
     break;
   }
-
-  // Collect CFG split points
-  if (n->is_MultiBranch() && !n->is_RangeCheck()) {
-    frc._tests.push(n);
-  }
 }
 
 //------------------------------final_graph_reshaping_walk---------------------

--- a/src/hotspot/share/opto/compile.hpp	Fri Nov 09 10:38:07 2018 +0100
+++ b/src/hotspot/share/opto/compile.hpp	Fri Nov 09 10:38:07 2018 +0100
@@ -1304,6 +1304,7 @@
   // Function calls made by the public function final_graph_reshaping.
   // No need to be made public as they are not called elsewhere.
   void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc);
+  void final_graph_reshaping_main_switch(Node* n, Final_Reshape_Counts& frc, uint nop);
   void final_graph_reshaping_walk( Node_Stack &nstack, Node *root, Final_Reshape_Counts &frc );
   void eliminate_redundant_card_marks(Node* n);