--- a/hotspot/src/cpu/sparc/vm/sparc.ad	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/cpu/sparc/vm/sparc.ad	Tue Dec 20 16:56:50 2011 +0100
@@ -6773,6 +6773,16 @@
   ins_pipe(empty);
 %}
 
+instruct membar_storestore() %{
+  match(MemBarStoreStore);
+  ins_cost(0);
+
+  size(0);
+  format %{ "!MEMBAR-storestore (empty encoding)" %}
+  ins_encode( );
+  ins_pipe(empty);
+%}
+
 //----------Register Move Instructions-----------------------------------------
 instruct roundDouble_nop(regD dst) %{
   match(Set dst (RoundDouble dst));

--- a/hotspot/src/cpu/x86/vm/x86_32.ad	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/cpu/x86/vm/x86_32.ad	Tue Dec 20 16:56:50 2011 +0100
@@ -7368,6 +7368,16 @@
   ins_pipe(empty);
 %}
 
+instruct membar_storestore() %{
+  match(MemBarStoreStore);
+  ins_cost(0);
+
+  size(0);
+  format %{ "MEMBAR-storestore (empty encoding)" %}
+  ins_encode( );
+  ins_pipe(empty);
+%}
+
 //----------Move Instructions--------------------------------------------------
 instruct castX2P(eAXRegP dst, eAXRegI src) %{
   match(Set dst (CastX2P src));

--- a/hotspot/src/cpu/x86/vm/x86_64.ad	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/cpu/x86/vm/x86_64.ad	Tue Dec 20 16:56:50 2011 +0100
@@ -6810,6 +6810,16 @@
   ins_pipe(empty);
 %}
 
+instruct membar_storestore() %{
+  match(MemBarStoreStore);
+  ins_cost(0);
+
+  size(0);
+  format %{ "MEMBAR-storestore (empty encoding)" %}
+  ins_encode( );
+  ins_pipe(empty);
+%}
+
 //----------Move Instructions--------------------------------------------------
 
 instruct castX2P(rRegP dst, rRegL src)

--- a/hotspot/src/share/vm/adlc/formssel.cpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/adlc/formssel.cpp	Tue Dec 20 16:56:50 2011 +0100
@@ -627,6 +627,7 @@
   if( strcmp(_matrule->_opType,"MemBarAcquire") == 0 ) return true;
   if( strcmp(_matrule->_opType,"MemBarReleaseLock") == 0 ) return true;
   if( strcmp(_matrule->_opType,"MemBarAcquireLock") == 0 ) return true;
+  if( strcmp(_matrule->_opType,"MemBarStoreStore") == 0 ) return true;
 
   return false;
 }
@@ -3978,7 +3979,8 @@
     !strcmp(_opType,"MemBarAcquireLock") ||
     !strcmp(_opType,"MemBarReleaseLock") ||
     !strcmp(_opType,"MemBarVolatile" ) ||
-    !strcmp(_opType,"MemBarCPUOrder" ) ;
+    !strcmp(_opType,"MemBarCPUOrder" ) ||
+    !strcmp(_opType,"MemBarStoreStore" );
 }
 
 bool MatchRule::is_ideal_loadPC() const {

--- a/hotspot/src/share/vm/opto/callnode.hpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/callnode.hpp	Tue Dec 20 16:56:50 2011 +0100
@@ -791,6 +791,10 @@
   // are defined in graphKit.cpp, which sets up the bidirectional relation.)
   InitializeNode* initialization();
 
+  // Return the corresponding storestore barrier (or null if none).
+  // Walks out edges to find it...
+  MemBarStoreStoreNode* storestore();
+
   // Convenience for initialization->maybe_set_complete(phase)
   bool maybe_set_complete(PhaseGVN* phase);
 };

--- a/hotspot/src/share/vm/opto/classes.hpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/classes.hpp	Tue Dec 20 16:56:50 2011 +0100
@@ -166,6 +166,7 @@
 macro(MemBarRelease)
 macro(MemBarReleaseLock)
 macro(MemBarVolatile)
+macro(MemBarStoreStore)
 macro(MergeMem)
 macro(MinI)
 macro(ModD)

--- a/hotspot/src/share/vm/opto/escape.cpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/escape.cpp	Tue Dec 20 16:56:50 2011 +0100
@@ -1595,6 +1595,7 @@
   GrowableArray<Node*> alloc_worklist;
   GrowableArray<Node*> addp_worklist;
   GrowableArray<Node*> ptr_cmp_worklist;
+  GrowableArray<Node*> storestore_worklist;
   PhaseGVN* igvn = _igvn;
 
   // Push all useful nodes onto CG list and set their type.
@@ -1618,6 +1619,11 @@
                (n->Opcode() == Op_CmpP || n->Opcode() == Op_CmpN)) {
       // Compare pointers nodes
       ptr_cmp_worklist.append(n);
+    } else if (n->is_MemBarStoreStore()) {
+      // Collect all MemBarStoreStore nodes so that depending on the
+      // escape status of the associated Allocate node some of them
+      // may be eliminated.
+      storestore_worklist.append(n);
     }
     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
       Node* m = n->fast_out(i);   // Get user
@@ -1724,11 +1730,20 @@
   uint alloc_length = alloc_worklist.length();
   for (uint next = 0; next < alloc_length; ++next) {
     Node* n = alloc_worklist.at(next);
-    if (ptnode_adr(n->_idx)->escape_state() == PointsToNode::NoEscape) {
+    PointsToNode::EscapeState es = ptnode_adr(n->_idx)->escape_state();
+    if (es == PointsToNode::NoEscape) {
       has_non_escaping_obj = true;
       if (n->is_Allocate()) {
         find_init_values(n, &visited, igvn);
+        // The object allocated by this Allocate node will never be
+        // seen by an other thread. Mark it so that when it is
+        // expanded no MemBarStoreStore is added.
+        n->as_Allocate()->initialization()->set_does_not_escape();
       }
+    } else if ((es == PointsToNode::ArgEscape) && n->is_Allocate()) {
+      // Same as above. Mark this Allocate node so that when it is
+      // expanded no MemBarStoreStore is added.
+      n->as_Allocate()->initialization()->set_does_not_escape();
     }
   }
 
@@ -1874,6 +1889,25 @@
       igvn->hash_delete(_pcmp_eq);
   }
 
+  // For MemBarStoreStore nodes added in library_call.cpp, check
+  // escape status of associated AllocateNode and optimize out
+  // MemBarStoreStore node if the allocated object never escapes.
+  while (storestore_worklist.length() != 0) {
+    Node *n = storestore_worklist.pop();
+    MemBarStoreStoreNode *storestore = n ->as_MemBarStoreStore();
+    Node *alloc = storestore->in(MemBarNode::Precedent)->in(0);
+    assert (alloc->is_Allocate(), "storestore should point to AllocateNode");
+    PointsToNode::EscapeState es = ptnode_adr(alloc->_idx)->escape_state();
+    if (es == PointsToNode::NoEscape || es == PointsToNode::ArgEscape) {
+      MemBarNode* mb = MemBarNode::make(C, Op_MemBarCPUOrder, Compile::AliasIdxBot);
+      mb->init_req(TypeFunc::Memory, storestore->in(TypeFunc::Memory));
+      mb->init_req(TypeFunc::Control, storestore->in(TypeFunc::Control));
+
+      _igvn->register_new_node_with_optimizer(mb);
+      _igvn->replace_node(storestore, mb);
+    }
+  }
+
 #ifndef PRODUCT
   if (PrintEscapeAnalysis) {
     dump(); // Dump ConnectionGraph

--- a/hotspot/src/share/vm/opto/graphKit.cpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/graphKit.cpp	Tue Dec 20 16:56:50 2011 +0100
@@ -3337,6 +3337,19 @@
   return NULL;
 }
 
+// Trace Allocate -> Proj[Parm] -> MemBarStoreStore
+MemBarStoreStoreNode* AllocateNode::storestore() {
+  ProjNode* rawoop = proj_out(AllocateNode::RawAddress);
+  if (rawoop == NULL)  return NULL;
+  for (DUIterator_Fast imax, i = rawoop->fast_outs(imax); i < imax; i++) {
+    Node* storestore = rawoop->fast_out(i);
+    if (storestore->is_MemBarStoreStore()) {
+      return storestore->as_MemBarStoreStore();
+    }
+  }
+  return NULL;
+}
+
 //----------------------------- loop predicates ---------------------------
 
 //------------------------------add_predicate_impl----------------------------

--- a/hotspot/src/share/vm/opto/library_call.cpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/library_call.cpp	Tue Dec 20 16:56:50 2011 +0100
@@ -4193,12 +4193,17 @@
   Node* raw_obj = alloc_obj->in(1);
   assert(alloc_obj->is_CheckCastPP() && raw_obj->is_Proj() && raw_obj->in(0)->is_Allocate(), "");
 
+  AllocateNode* alloc = NULL;
   if (ReduceBulkZeroing) {
     // We will be completely responsible for initializing this object -
     // mark Initialize node as complete.
-    AllocateNode* alloc = AllocateNode::Ideal_allocation(alloc_obj, &_gvn);
+    alloc = AllocateNode::Ideal_allocation(alloc_obj, &_gvn);
     // The object was just allocated - there should be no any stores!
     guarantee(alloc != NULL && alloc->maybe_set_complete(&_gvn), "");
+    // Mark as complete_with_arraycopy so that on AllocateNode
+    // expansion, we know this AllocateNode is initialized by an array
+    // copy and a StoreStore barrier exists after the array copy.
+    alloc->initialization()->set_complete_with_arraycopy();
   }
 
   // Copy the fastest available way.
@@ -4260,7 +4265,18 @@
   }
 
   // Do not let reads from the cloned object float above the arraycopy.
-  insert_mem_bar(Op_MemBarCPUOrder);
+  if (alloc != NULL) {
+    // Do not let stores that initialize this object be reordered with
+    // a subsequent store that would make this object accessible by
+    // other threads.
+    // Record what AllocateNode this StoreStore protects so that
+    // escape analysis can go from the MemBarStoreStoreNode to the
+    // AllocateNode and eliminate the MemBarStoreStoreNode if possible
+    // based on the escape status of the AllocateNode.
+    insert_mem_bar(Op_MemBarStoreStore, alloc->proj_out(AllocateNode::RawAddress));
+  } else {
+    insert_mem_bar(Op_MemBarCPUOrder);
+  }
 }
 
 //------------------------inline_native_clone----------------------------
@@ -5003,7 +5019,16 @@
   // the membar also.
   //
   // Do not let reads from the cloned object float above the arraycopy.
-  if (InsertMemBarAfterArraycopy || alloc != NULL)
+  if (alloc != NULL) {
+    // Do not let stores that initialize this object be reordered with
+    // a subsequent store that would make this object accessible by
+    // other threads.
+    // Record what AllocateNode this StoreStore protects so that
+    // escape analysis can go from the MemBarStoreStoreNode to the
+    // AllocateNode and eliminate the MemBarStoreStoreNode if possible
+    // based on the escape status of the AllocateNode.
+    insert_mem_bar(Op_MemBarStoreStore, alloc->proj_out(AllocateNode::RawAddress));
+  } else if (InsertMemBarAfterArraycopy)
     insert_mem_bar(Op_MemBarCPUOrder);
 }
 

--- a/hotspot/src/share/vm/opto/macro.cpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/macro.cpp	Tue Dec 20 16:56:50 2011 +0100
@@ -1088,6 +1088,12 @@
   Node* klass_node        = alloc->in(AllocateNode::KlassNode);
   Node* initial_slow_test = alloc->in(AllocateNode::InitialTest);
 
+  Node* storestore = alloc->storestore();
+  if (storestore != NULL) {
+    // Break this link that is no longer useful and confuses register allocation
+    storestore->set_req(MemBarNode::Precedent, top());
+  }
+
   assert(ctrl != NULL, "must have control");
   // We need a Region and corresponding Phi's to merge the slow-path and fast-path results.
   // they will not be used if "always_slow" is set
@@ -1289,10 +1295,66 @@
                                    0, new_alloc_bytes, T_LONG);
     }
 
+    InitializeNode* init = alloc->initialization();
     fast_oop_rawmem = initialize_object(alloc,
                                         fast_oop_ctrl, fast_oop_rawmem, fast_oop,
                                         klass_node, length, size_in_bytes);
 
+    // If initialization is performed by an array copy, any required
+    // MemBarStoreStore was already added. If the object does not
+    // escape no need for a MemBarStoreStore. Otherwise we need a
+    // MemBarStoreStore so that stores that initialize this object
+    // can't be reordered with a subsequent store that makes this
+    // object accessible by other threads.
+    if (init == NULL || (!init->is_complete_with_arraycopy() && !init->does_not_escape())) {
+      if (init == NULL || init->req() < InitializeNode::RawStores) {
+        // No InitializeNode or no stores captured by zeroing
+        // elimination. Simply add the MemBarStoreStore after object
+        // initialization.
+        MemBarNode* mb = MemBarNode::make(C, Op_MemBarStoreStore, Compile::AliasIdxBot, fast_oop_rawmem);
+        transform_later(mb);
+
+        mb->init_req(TypeFunc::Memory, fast_oop_rawmem);
+        mb->init_req(TypeFunc::Control, fast_oop_ctrl);
+        fast_oop_ctrl = new (C, 1) ProjNode(mb,TypeFunc::Control);
+        transform_later(fast_oop_ctrl);
+        fast_oop_rawmem = new (C, 1) ProjNode(mb,TypeFunc::Memory);
+        transform_later(fast_oop_rawmem);
+      } else {
+        // Add the MemBarStoreStore after the InitializeNode so that
+        // all stores performing the initialization that were moved
+        // before the InitializeNode happen before the storestore
+        // barrier.
+
+        Node* init_ctrl = init->proj_out(TypeFunc::Control);
+        Node* init_mem = init->proj_out(TypeFunc::Memory);
+
+        MemBarNode* mb = MemBarNode::make(C, Op_MemBarStoreStore, Compile::AliasIdxBot);
+        transform_later(mb);
+
+        Node* ctrl = new (C, 1) ProjNode(init,TypeFunc::Control);
+        transform_later(ctrl);
+        Node* mem = new (C, 1) ProjNode(init,TypeFunc::Memory);
+        transform_later(mem);
+
+        // The MemBarStoreStore depends on control and memory coming
+        // from the InitializeNode
+        mb->init_req(TypeFunc::Memory, mem);
+        mb->init_req(TypeFunc::Control, ctrl);
+
+        ctrl = new (C, 1) ProjNode(mb,TypeFunc::Control);
+        transform_later(ctrl);
+        mem = new (C, 1) ProjNode(mb,TypeFunc::Memory);
+        transform_later(mem);
+
+        // All nodes that depended on the InitializeNode for control
+        // and memory must now depend on the MemBarNode that itself
+        // depends on the InitializeNode
+        _igvn.replace_node(init_ctrl, ctrl);
+        _igvn.replace_node(init_mem, mem);
+      }
+    }
+
     if (C->env()->dtrace_extended_probes()) {
       // Slow-path call
       int size = TypeFunc::Parms + 2;

--- a/hotspot/src/share/vm/opto/memnode.cpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/memnode.cpp	Tue Dec 20 16:56:50 2011 +0100
@@ -2721,6 +2721,7 @@
   case Op_MemBarVolatile:  return new(C, len) MemBarVolatileNode(C, atp, pn);
   case Op_MemBarCPUOrder:  return new(C, len) MemBarCPUOrderNode(C, atp, pn);
   case Op_Initialize:      return new(C, len) InitializeNode(C,     atp, pn);
+  case Op_MemBarStoreStore: return new(C, len) MemBarStoreStoreNode(C,  atp, pn);
   default:                 ShouldNotReachHere(); return NULL;
   }
 }
@@ -2870,7 +2871,7 @@
 
 //---------------------------InitializeNode------------------------------------
 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
-  : _is_complete(Incomplete),
+  : _is_complete(Incomplete), _does_not_escape(false),
     MemBarNode(C, adr_type, rawoop)
 {
   init_class_id(Class_Initialize);

--- a/hotspot/src/share/vm/opto/memnode.hpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/memnode.hpp	Tue Dec 20 16:56:50 2011 +0100
@@ -918,6 +918,15 @@
   virtual int Opcode() const;
 };
 
+class MemBarStoreStoreNode: public MemBarNode {
+public:
+  MemBarStoreStoreNode(Compile* C, int alias_idx, Node* precedent)
+    : MemBarNode(C, alias_idx, precedent) {
+    init_class_id(Class_MemBarStoreStore);
+  }
+  virtual int Opcode() const;
+};
+
 // Ordering between a volatile store and a following volatile load.
 // Requires multi-CPU visibility?
 class MemBarVolatileNode: public MemBarNode {
@@ -950,6 +959,8 @@
   };
   int _is_complete;
 
+  bool _does_not_escape;
+
 public:
   enum {
     Control    = TypeFunc::Control,
@@ -989,6 +1000,9 @@
   void set_complete(PhaseGVN* phase);
   void set_complete_with_arraycopy() { _is_complete = Complete | WithArraycopy; }
 
+  bool does_not_escape() { return _does_not_escape; }
+  void set_does_not_escape() { _does_not_escape = true; }
+
 #ifdef ASSERT
   // ensure all non-degenerate stores are ordered and non-overlapping
   bool stores_are_sane(PhaseTransform* phase);

--- a/hotspot/src/share/vm/opto/node.hpp	Wed Dec 07 11:35:03 2011 +0100
+++ b/hotspot/src/share/vm/opto/node.hpp	Tue Dec 20 16:56:50 2011 +0100
@@ -97,6 +97,7 @@
 class MachTempNode;
 class Matcher;
 class MemBarNode;
+class MemBarStoreStoreNode;
 class MemNode;
 class MergeMemNode;
 class MultiNode;
@@ -564,7 +565,8 @@
         DEFINE_CLASS_ID(NeverBranch, MultiBranch, 2)
       DEFINE_CLASS_ID(Start,       Multi, 2)
       DEFINE_CLASS_ID(MemBar,      Multi, 3)
-        DEFINE_CLASS_ID(Initialize,    MemBar, 0)
+        DEFINE_CLASS_ID(Initialize,       MemBar, 0)
+        DEFINE_CLASS_ID(MemBarStoreStore, MemBar, 1)
 
     DEFINE_CLASS_ID(Mach,  Node, 1)
       DEFINE_CLASS_ID(MachReturn, Mach, 0)
@@ -744,6 +746,7 @@
   DEFINE_CLASS_QUERY(MachTemp)
   DEFINE_CLASS_QUERY(Mem)
   DEFINE_CLASS_QUERY(MemBar)
+  DEFINE_CLASS_QUERY(MemBarStoreStore)
   DEFINE_CLASS_QUERY(MergeMem)
   DEFINE_CLASS_QUERY(Multi)
   DEFINE_CLASS_QUERY(MultiBranch)