--- a/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/gc/shared/c2/barrierSetC2.hpp	Wed Oct 17 10:19:13 2018 +0200
@@ -213,8 +213,8 @@
   virtual void register_potential_barrier_node(Node* node) const { }
   virtual void unregister_potential_barrier_node(Node* node) const { }
   virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
-  virtual void enqueue_useful_gc_barrier(Unique_Node_List &worklist, Node* node) const {}
-  virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful) const {}
+  virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {}
+  virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {}
   virtual void add_users_to_worklist(Unique_Node_List* worklist) const {}
 
   // Allow barrier sets to have shared state that is preserved across a compilation unit.

--- a/src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -102,7 +102,7 @@
   }
 }
 
-void ZBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &useful) const {
+void ZBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {
   // Remove useless LoadBarrier nodes
   ZBarrierSetC2State* s = state();
   for (int i = s->load_barrier_count()-1; i >= 0; i--) {
@@ -113,9 +113,9 @@
   }
 }
 
-void ZBarrierSetC2::enqueue_useful_gc_barrier(Unique_Node_List &worklist, Node* node) const {
+void ZBarrierSetC2::enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {
   if (node->is_LoadBarrier() && !node->as_LoadBarrier()->has_true_uses()) {
-    worklist.push(node);
+    igvn->_worklist.push(node);
   }
 }
 

--- a/src/hotspot/share/gc/z/c2/zBarrierSetC2.hpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/gc/z/c2/zBarrierSetC2.hpp	Wed Oct 17 10:19:13 2018 +0200
@@ -189,9 +189,9 @@
   virtual bool has_load_barriers() const { return true; }
   virtual bool is_gc_barrier_node(Node* node) const;
   virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
-  virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful) const;
+  virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const;
   virtual void add_users_to_worklist(Unique_Node_List* worklist) const;
-  virtual void enqueue_useful_gc_barrier(Unique_Node_List &worklist, Node* node) const;
+  virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const;
   virtual void register_potential_barrier_node(Node* node) const;
   virtual void unregister_potential_barrier_node(Node* node) const;
   virtual bool array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, ArrayCopyPhase phase) const;

--- a/src/hotspot/share/opto/cfgnode.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/cfgnode.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -24,6 +24,7 @@
 
 #include "precompiled.hpp"
 #include "classfile/systemDictionary.hpp"
+#include "gc/shared/c2/barrierSetC2.hpp"
 #include "memory/allocation.inline.hpp"
 #include "memory/resourceArea.hpp"
 #include "oops/objArrayKlass.hpp"
@@ -1447,7 +1448,10 @@
   } else return NULL;
 
   // Build int->bool conversion
-  Node *n = new Conv2BNode( cmp->in(1) );
+  Node *in1 = cmp->in(1);
+  BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+  in1 = bs->step_over_gc_barrier(in1);
+  Node *n = new Conv2BNode(in1);
   if( flipped )
     n = new XorINode( phase->transform(n), phase->intcon(1) );
 
@@ -1813,7 +1817,12 @@
         if (can_reshape && igvn != NULL) {
           igvn->_worklist.push(r);
         }
-        set_req(j, top);        // Nuke it down
+        // Nuke it down
+        if (can_reshape) {
+          set_req_X(j, top, igvn);
+        } else {
+          set_req(j, top);
+        }
         progress = this;        // Record progress
       }
     }

--- a/src/hotspot/share/opto/compile.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/compile.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -421,7 +421,7 @@
     }
   }
   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
-  bs->eliminate_useless_gc_barriers(useful);
+  bs->eliminate_useless_gc_barriers(useful, this);
   // clean up the late inline lists
   remove_useless_late_inlines(&_string_late_inlines, useful);
   remove_useless_late_inlines(&_boxing_late_inlines, useful);

--- a/src/hotspot/share/opto/graphKit.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/graphKit.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -3726,6 +3726,10 @@
   if (ptr == NULL) {     // reduce dumb test in callers
     return NULL;
   }
+
+  BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+  ptr = bs->step_over_gc_barrier(ptr);
+
   if (ptr->is_CheckCastPP()) { // strip only one raw-to-oop cast
     ptr = ptr->in(1);
     if (ptr == NULL) return NULL;

--- a/src/hotspot/share/opto/macro.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/macro.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -434,7 +434,10 @@
       if (val == mem) {
         values.at_put(j, mem);
       } else if (val->is_Store()) {
-        values.at_put(j, val->in(MemNode::ValueIn));
+        Node* n = val->in(MemNode::ValueIn);
+        BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+        n = bs->step_over_gc_barrier(n);
+        values.at_put(j, n);
       } else if(val->is_Proj() && val->in(0) == alloc) {
         values.at_put(j, _igvn.zerocon(ft));
       } else if (val->is_Phi()) {
@@ -546,7 +549,10 @@
       // hit a sentinel, return appropriate 0 value
       return _igvn.zerocon(ft);
     } else if (mem->is_Store()) {
-      return mem->in(MemNode::ValueIn);
+      Node* n = mem->in(MemNode::ValueIn);
+      BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+      n = bs->step_over_gc_barrier(n);
+      return n;
     } else if (mem->is_Phi()) {
       // attempt to produce a Phi reflecting the values on the input paths of the Phi
       Node_Stack value_phis(a, 8);

--- a/src/hotspot/share/opto/memnode.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/memnode.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -924,8 +924,10 @@
     if (ac->as_ArrayCopy()->is_clonebasic()) {
       assert(ld_alloc != NULL, "need an alloc");
       assert(addp->is_AddP(), "address must be addp");
-      assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
-      assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
+      assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address");
+      BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+      assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern");
+      assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern");
       addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
       addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
     } else {
@@ -1081,6 +1083,8 @@
         (tp != NULL) && tp->is_ptr_to_boxed_value()) {
       intptr_t ignore = 0;
       Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
+      BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
+      base = bs->step_over_gc_barrier(base);
       if (base != NULL && base->is_Proj() &&
           base->as_Proj()->_con == TypeFunc::Parms &&
           base->in(0)->is_CallStaticJava() &&

--- a/src/hotspot/share/opto/node.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/node.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -1396,7 +1396,7 @@
             // and remove_globally_dead_node().
             igvn->add_users_to_worklist( n );
           } else {
-            BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn->_worklist, n);
+            BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
           }
         }
       }

--- a/src/hotspot/share/opto/phaseX.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/phaseX.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -1375,7 +1375,7 @@
                 assert(!(i < imax), "sanity");
               }
             } else {
-              BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(_worklist, in);
+              BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(this, in);
             }
             if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
                 in->is_Proj() && in->in(0) != NULL && in->in(0)->is_Initialize()) {
@@ -2089,6 +2089,8 @@
     default:
       break;
     }
+
+    BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, old);
   }
 
 }

--- a/src/hotspot/share/opto/subnode.cpp	Tue Oct 23 13:47:17 2018 +0800
+++ b/src/hotspot/share/opto/subnode.cpp	Wed Oct 17 10:19:13 2018 +0200
@@ -883,9 +883,7 @@
   //   LoadBarrier?(LoadP(LoadP(AddP(foo:Klass, #java_mirror))))
   //   or NULL if not matching.
   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
-  if (bs->is_gc_barrier_node(n)) {
     n = bs->step_over_gc_barrier(n);
-  }
 
   if (n->Opcode() != Op_LoadP) return NULL;
 
@@ -959,8 +957,14 @@
     if (k1 && (k2 || conk2)) {
       Node* lhs = k1;
       Node* rhs = (k2 != NULL) ? k2 : conk2;
-      this->set_req(1, lhs);
-      this->set_req(2, rhs);
+      PhaseIterGVN* igvn = phase->is_IterGVN();
+      if (igvn != NULL) {
+        set_req_X(1, lhs, igvn);
+        set_req_X(2, rhs, igvn);
+      } else {
+        set_req(1, lhs);
+        set_req(2, rhs);
+      }
       return this;
     }
   }