--- /dev/null	2017-03-07 11:44:12.271151064 +0100
+++ new/src/share/vm/gc/shared/c2BarrierSetCodeGen.cpp	2017-04-25 16:46:28.223171249 +0200
@@ -0,0 +1,529 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "opto/arraycopynode.hpp"
+#include "opto/graphKit.hpp"
+#include "opto/idealKit.hpp"
+#include "opto/narrowptrnode.hpp"
+#include "gc/shared/c2BarrierSetCodeGen.hpp"
+#include "utilities/macros.hpp"
+
+Node* C2BarrierSetCodeGen::store_at_resolved(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, Node* val, const Type* val_type, BasicType bt, C2DecoratorSet decorators) {
+  bool mismatched = (decorators & C2_MISMATCHED) != 0;
+  bool is_vol = (decorators & C2_MO_VOLATILE) != 0;
+  bool is_release = (decorators & C2_MO_RELEASE) != 0;
+  bool unaligned = (decorators & C2_ACCESS_UNALIGNED) != 0;
+  bool requires_atomic_access = (decorators & C2_ACCESS_ATOMIC) != 0;
+
+  if (bt == T_DOUBLE) {
+    val = kit->dstore_rounding(val);
+  }
+
+  MemNode::MemOrd mo;
+  if (is_vol || is_release) {
+    mo = MemNode::release;
+  } else {
+    // Volatile fields need releasing stores.
+    // Non-volatile fields also need releasing stores if they hold an
+    // object reference, because the object reference might point to
+    // a freshly created object.
+    // Conservatively release stores of object references.
+    mo = StoreNode::release_if_reference(bt);
+  }
+
+  return kit->store_to_memory(kit->control(), adr, val, bt, adr_type, mo, requires_atomic_access, unaligned, mismatched);
+}
+
+Node* C2BarrierSetCodeGen::load_at_resolved(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, const Type* val_type, BasicType bt, C2DecoratorSet decorators) {
+  bool mismatched = (decorators & C2_MISMATCHED) != 0;
+  bool is_vol = (decorators & C2_MO_VOLATILE) != 0;
+  bool is_acquire = (decorators & C2_MO_RELEASE) != 0;
+  bool anonymous = (decorators & C2_ACCESS_ON_ANONYMOUS) != 0;
+  bool requires_atomic_access = (decorators & C2_ACCESS_ATOMIC) != 0;
+  bool unaligned = (decorators & C2_ACCESS_UNALIGNED) != 0;
+  bool no_control = (decorators & C2_ACCESS_FREE_CONTROL) != 0;
+
+  MemNode::MemOrd mo;
+  if (is_vol || is_acquire) {
+    mo = MemNode::acquire;
+  } else {
+    mo = MemNode::unordered;
+  }
+
+  // To be valid, unsafe loads may depend on other conditions than
+  // the one that guards them: pin the Load node
+  return kit->make_load(!no_control ? kit->control() : NULL, adr, val_type, bt, adr_type, mo,
+                        anonymous ? LoadNode::Pinned : LoadNode::DependsOnlyOnTest,
+                        requires_atomic_access, unaligned, mismatched);
+}
+
+Node* C2BarrierSetCodeGen::store_at(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, Node* val, const Type* val_type, BasicType bt, C2DecoratorSet decorators) {
+  decorators = fixup_decorators(decorators);
+  bool mismatched = (decorators & C2_MISMATCHED) != 0;
+  bool is_vol = (decorators & C2_MO_VOLATILE) != 0;
+  bool is_release = (decorators & C2_MO_RELEASE) != 0;
+  bool is_relaxed = (decorators & C2_MO_RELAXED) != 0;
+  bool anonymous = (decorators & C2_ACCESS_ON_ANONYMOUS) != 0;
+  bool on_heap = (decorators & C2_ACCESS_ON_HEAP) != 0;
+
+  // We will need memory barriers unless we can determine a unique
+  // alias category for this reference.  (Note:  If for some reason
+  // the barriers get omitted and the unsafe reference begins to "pollute"
+  // the alias analysis of the rest of the graph, either Compile::can_alias
+  // or Compile::must_alias will throw a diagnostic assert.)
+  bool need_cpu_mem_bar = anonymous && (!is_relaxed || mismatched || !on_heap);
+
+  if (need_cpu_mem_bar) {
+    kit->insert_mem_bar(Op_MemBarCPUOrder);
+  }
+  // If reference is volatile, prevent following memory ops from
+  // floating down past the volatile write.  Also prevents commoning
+  // another volatile read.
+  if (is_vol || is_release) {
+    kit->insert_mem_bar(Op_MemBarRelease);
+  }
+
+  Node* store = store_at_resolved(kit, obj, adr, adr_type, val, val_type, bt, decorators);
+
+  // If reference is volatile, prevent following volatiles ops from
+  // floating up before the volatile write.
+    // If not multiple copy atomic, we do the MemBarVolatile before the load.
+  if (is_vol && !support_IRIW_for_not_multiple_copy_atomic_cpu) {
+    kit->insert_mem_bar(Op_MemBarVolatile); // Use fat membar
+  }
+  if (need_cpu_mem_bar) {
+    kit->insert_mem_bar(Op_MemBarCPUOrder);
+  }
+
+  return store;
+}
+
+Node* C2BarrierSetCodeGen::load_at(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, const Type* val_type, BasicType bt, C2DecoratorSet decorators) {
+  decorators = fixup_decorators(decorators);
+  bool mismatched = (decorators & C2_MISMATCHED) != 0;
+  bool is_vol = (decorators & C2_MO_VOLATILE) != 0;
+  bool is_acquire = (decorators & C2_MO_ACQUIRE) != 0;
+  bool is_relaxed = (decorators & C2_MO_RELAXED) != 0;
+  bool anonymous = (decorators & C2_ACCESS_ON_ANONYMOUS) != 0;
+  bool on_heap = (decorators & C2_ACCESS_ON_HEAP) != 0;
+
+  bool need_cpu_mem_bar = anonymous && (!is_relaxed || mismatched || !on_heap);
+
+  // Memory barrier to prevent normal and 'unsafe' accesses from
+  // bypassing each other.  Happens after null checks, so the
+  // exception paths do not take memory state from the memory barrier,
+  // so there's no problems making a strong assert about mixing users
+  // of safe & unsafe memory.
+  if (need_cpu_mem_bar) {
+    kit->insert_mem_bar(Op_MemBarCPUOrder);
+  }
+  if (is_vol && support_IRIW_for_not_multiple_copy_atomic_cpu) {
+    kit->insert_mem_bar(Op_MemBarVolatile);
+  }
+
+  Node* p = load_at_resolved(kit, obj, adr, adr_type, val_type, bt, decorators);
+
+  if (is_vol || is_acquire) {
+    kit->insert_mem_bar(Op_MemBarAcquire, p);
+  }
+  if (need_cpu_mem_bar) {
+    kit->insert_mem_bar(Op_MemBarCPUOrder);
+  }
+
+  return p;
+}
+
+//--------------------------- atomic operations---------------------------------
+
+static MemNode::MemOrd atomic_op_mo_from_decorators(C2DecoratorSet decorators) {
+  if ((decorators & C2_MO_RELEASE) != 0) {
+    return MemNode::release;
+  } else if ((decorators & C2_MO_ACQUIRE) != 0) {
+    return MemNode::acquire;
+  } else if ((decorators & C2_MO_VOLATILE) != 0) {
+    return MemNode::seqcst;
+  } else {
+    return MemNode::unordered;
+  }
+}
+
+static void pin_atomic_op(GraphKit* kit, Node* load_store, int alias_idx) {
+  // SCMemProjNodes represent the memory state of a LoadStore. Their
+  // main role is to prevent LoadStore nodes from being optimized away
+  // when their results aren't used.
+  Node* proj = kit->gvn().transform(new SCMemProjNode(load_store));
+  kit->set_memory(proj, alias_idx);
+}
+
+static Node* atomic_op_membar_prologue(GraphKit* kit, C2DecoratorSet decorators, int alias_idx) {
+  bool is_release = (decorators & C2_MO_RELEASE) != 0;
+  bool is_volatile = (decorators & C2_MO_VOLATILE) != 0;
+  // Memory-model-wise, a LoadStore acts like a little synchronized
+  // block, so needs barriers on each side.  These don't translate
+  // into actual barriers on most machines, but we still need rest of
+  // compiler to respect ordering.
+  if (is_release) {
+    kit->insert_mem_bar(Op_MemBarRelease);
+  } else if (is_volatile) {
+    if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
+      kit->insert_mem_bar(Op_MemBarVolatile);
+    } else {
+      kit->insert_mem_bar(Op_MemBarRelease);
+    }
+  }
+  kit->insert_mem_bar(Op_MemBarCPUOrder);
+
+  // 4984716: MemBars must be inserted before this
+  //          memory node in order to avoid a false
+  //          dependency which will confuse the scheduler.
+  Node *mem = kit->memory(alias_idx);
+  return mem;
+}
+
+static void atomic_op_membar_epilogue(GraphKit* kit, C2DecoratorSet decorators) {
+  bool is_acquire = (decorators & C2_MO_ACQUIRE) != 0;
+  bool is_volatile = (decorators & C2_MO_VOLATILE) != 0;
+  // Add the trailing membar surrounding the access
+  kit->insert_mem_bar(Op_MemBarCPUOrder);
+  if (is_acquire || is_volatile) {
+    kit->insert_mem_bar(Op_MemBarAcquire);
+  }
+}
+
+Node* C2BarrierSetCodeGen::cas_val_at_resolved(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                               Node* expected_val, Node* new_val, const Type* value_type,
+                                               Node* mem, Node*& load_store, BasicType bt, C2DecoratorSet decorators) {
+  bool is_obj = bt == T_OBJECT || bt == T_ARRAY;
+  MemNode::MemOrd mo = atomic_op_mo_from_decorators(decorators);
+
+  if (is_obj) {
+#ifdef _LP64
+    if (adr->bottom_type()->is_ptr_to_narrowoop()) {
+      Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
+      Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));
+      load_store = kit->gvn().transform(new CompareAndExchangeNNode(kit->control(), mem, adr, newval_enc, oldval_enc, adr_type, value_type->make_narrowoop(), mo));
+    } else
+#endif
+      {
+        load_store = kit->gvn().transform(new CompareAndExchangePNode(kit->control(), mem, adr, new_val, expected_val, adr_type, value_type->is_oopptr(), mo));
+
+      }
+  } else {
+    switch (bt) {
+      case T_BYTE: {
+        load_store = kit->gvn().transform(new CompareAndExchangeBNode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));
+        break;
+      }
+      case T_SHORT: {
+        load_store = kit->gvn().transform(new CompareAndExchangeSNode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));
+        break;
+      }
+      case T_INT: {
+        load_store = kit->gvn().transform(new CompareAndExchangeINode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));
+        break;
+      }
+      case T_LONG: {
+        load_store = kit->gvn().transform(new CompareAndExchangeLNode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));
+        break;
+      }
+      default:
+        ShouldNotReachHere();
+    }
+  }
+
+  pin_atomic_op(kit, load_store, alias_idx);
+
+  Node* result = load_store;
+#ifdef _LP64
+  if (is_obj && adr->bottom_type()->is_ptr_to_narrowoop()) {
+    result = kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));
+  }
+#endif
+
+  return result;
+}
+
+Node* C2BarrierSetCodeGen::cas_bool_at_resolved(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                                Node* expected_val, Node* new_val, const Type* value_type,
+                                                Node* mem, BasicType bt, C2DecoratorSet decorators) {
+  bool is_obj = bt == T_OBJECT || bt == T_ARRAY;
+  bool is_weak_cas = (decorators & C2_WEAK_CAS) != 0;
+
+  MemNode::MemOrd mo = atomic_op_mo_from_decorators(decorators);
+
+  Node* load_store = NULL;
+  if (is_obj) {
+#ifdef _LP64
+    if (adr->bottom_type()->is_ptr_to_narrowoop()) {
+      Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
+      Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));
+      if (is_weak_cas) {
+        load_store = kit->gvn().transform(new WeakCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
+      } else {
+        load_store = kit->gvn().transform(new CompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
+      }
+    } else
+#endif
+    {
+      if (is_weak_cas) {
+        load_store = kit->gvn().transform(new WeakCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
+      } else {
+        load_store = kit->gvn().transform(new CompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
+      }
+    }
+  } else {
+    switch(bt) {
+      case T_BYTE: {
+        if (is_weak_cas) {
+          load_store = kit->gvn().transform(new WeakCompareAndSwapBNode(kit->control(), mem, adr, new_val, expected_val, mo));
+        } else {
+          load_store = kit->gvn().transform(new CompareAndSwapBNode(kit->control(), mem, adr, new_val, expected_val, mo));
+        }
+        break;
+      }
+      case T_SHORT: {
+        if (is_weak_cas) {
+          load_store = kit->gvn().transform(new WeakCompareAndSwapSNode(kit->control(), mem, adr, new_val, expected_val, mo));
+        } else {
+          load_store = kit->gvn().transform(new CompareAndSwapSNode(kit->control(), mem, adr, new_val, expected_val, mo));
+        }
+        break;
+      }
+      case T_INT: {
+        if (is_weak_cas) {
+          load_store = kit->gvn().transform(new WeakCompareAndSwapINode(kit->control(), mem, adr, new_val, expected_val, mo));
+        } else {
+          load_store = kit->gvn().transform(new CompareAndSwapINode(kit->control(), mem, adr, new_val, expected_val, mo));
+        }
+        break;
+      }
+      case T_LONG: {
+        if (is_weak_cas) {
+          load_store = kit->gvn().transform(new WeakCompareAndSwapLNode(kit->control(), mem, adr, new_val, expected_val, mo));
+        } else {
+          load_store = kit->gvn().transform(new CompareAndSwapLNode(kit->control(), mem, adr, new_val, expected_val, mo));
+        }
+        break;
+      }
+      default:
+        ShouldNotReachHere();
+    }
+  }
+
+  pin_atomic_op(kit, load_store, alias_idx);
+
+  return load_store;
+}
+
+Node* C2BarrierSetCodeGen::swap_at_resolved(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                            Node* new_val, const Type* value_type,
+                                            Node* mem, Node*& load_store, BasicType bt, C2DecoratorSet decorators) {
+  bool is_obj = bt == T_OBJECT || bt == T_ARRAY;
+  if (is_obj) {
+#ifdef _LP64
+    if (adr->bottom_type()->is_ptr_to_narrowoop()) {
+      Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
+      load_store = kit->gvn().transform(new GetAndSetNNode(kit->control(), mem, adr, newval_enc, adr_type, value_type->make_narrowoop()));
+    } else
+#endif
+    {
+      load_store = kit->gvn().transform(new GetAndSetPNode(kit->control(), mem, adr, new_val, adr_type, value_type->is_oopptr()));
+    }
+  } else  {
+    switch (bt) {
+      case T_BYTE:
+        load_store = kit->gvn().transform(new GetAndSetBNode(kit->control(), mem, adr, new_val, adr_type));
+        break;
+      case T_SHORT:
+        load_store = kit->gvn().transform(new GetAndSetSNode(kit->control(), mem, adr, new_val, adr_type));
+        break;
+      case T_INT:
+        load_store = kit->gvn().transform(new GetAndSetINode(kit->control(), mem, adr, new_val, adr_type));
+        break;
+      case T_LONG:
+        load_store = kit->gvn().transform(new GetAndSetLNode(kit->control(), mem, adr, new_val, adr_type));
+        break;
+      default:
+        ShouldNotReachHere();
+    }
+  }
+
+  pin_atomic_op(kit, load_store, alias_idx);
+
+  Node* result = load_store;
+#ifdef _LP64
+  if (is_obj && adr->bottom_type()->is_ptr_to_narrowoop()) {
+    result = kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));
+  }
+#endif
+
+  return result;
+}
+
+Node* C2BarrierSetCodeGen::fetch_and_add_at_resolved(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                                     Node* new_val, const Type* value_type,
+                                                     Node* mem, BasicType bt, C2DecoratorSet decorators) {
+  Node* load_store = NULL;
+  switch(bt) {
+    case T_BYTE:
+      load_store = kit->gvn().transform(new GetAndAddBNode(kit->control(), mem, adr, new_val, adr_type));
+      break;
+    case T_SHORT:
+      load_store = kit->gvn().transform(new GetAndAddSNode(kit->control(), mem, adr, new_val, adr_type));
+      break;
+    case T_INT:
+      load_store = kit->gvn().transform(new GetAndAddINode(kit->control(), mem, adr, new_val, adr_type));
+      break;
+    case T_LONG:
+      load_store = kit->gvn().transform(new GetAndAddLNode(kit->control(), mem, adr, new_val, adr_type));
+      break;
+    default:
+      ShouldNotReachHere();
+  }
+
+  pin_atomic_op(kit, load_store, alias_idx);
+
+  return load_store;
+}
+
+Node* C2BarrierSetCodeGen::cas_val_at(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                      Node* expected_val, Node* new_val, const Type* value_type,
+                                      BasicType bt, C2DecoratorSet decorators) {
+  decorators = fixup_decorators(decorators);
+  Node* mem = atomic_op_membar_prologue(kit, decorators, alias_idx);
+  Node* load_store = NULL;
+  Node* result = cas_val_at_resolved(kit, obj, adr, adr_type, alias_idx, expected_val, new_val, value_type, mem, load_store, bt, decorators);
+  atomic_op_membar_epilogue(kit, decorators);
+  return result;
+}
+
+Node* C2BarrierSetCodeGen::cas_bool_at(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                       Node* expected_val, Node* new_val, const Type* value_type,
+                                       BasicType bt, C2DecoratorSet decorators) {
+  decorators = fixup_decorators(decorators);
+  Node* mem = atomic_op_membar_prologue(kit, decorators, alias_idx);
+  Node* result = cas_bool_at_resolved(kit, obj, adr, adr_type, alias_idx, expected_val, new_val, value_type, mem, bt, decorators);
+  atomic_op_membar_epilogue(kit, decorators);
+  return result;
+}
+
+Node* C2BarrierSetCodeGen::swap_at(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                   Node* new_val, const Type* value_type,
+                                   BasicType bt, C2DecoratorSet decorators) {
+  decorators = fixup_decorators(decorators);
+  Node* mem = atomic_op_membar_prologue(kit, decorators, alias_idx);
+  Node* load_store = NULL;
+  Node* result = swap_at_resolved(kit, obj, adr, adr_type, alias_idx, new_val, value_type, mem, load_store, bt, decorators);
+  atomic_op_membar_epilogue(kit, decorators);
+  return result;
+}
+
+Node* C2BarrierSetCodeGen::fetch_and_add_at(GraphKit* kit, Node* obj, Node* adr, const TypePtr* adr_type, int alias_idx,
+                                            Node* new_val, const Type* value_type,
+                                            BasicType bt, C2DecoratorSet decorators) {
+  decorators = fixup_decorators(decorators);
+  Node* mem = atomic_op_membar_prologue(kit, decorators, alias_idx);
+  Node* result = fetch_and_add_at_resolved(kit, obj, adr, adr_type, alias_idx, new_val, value_type, mem, bt, decorators);
+  atomic_op_membar_epilogue(kit, decorators);
+  return result;
+}
+
+void C2BarrierSetCodeGen::clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) {
+  // Exclude the header but include array length to copy by 8 bytes words.
+  // Can't use base_offset_in_bytes(bt) since basic type is unknown.
+  int base_off = is_array ? arrayOopDesc::length_offset_in_bytes() :
+                            instanceOopDesc::base_offset_in_bytes();
+  // base_off:
+  // 8  - 32-bit VM
+  // 12 - 64-bit VM, compressed klass
+  // 16 - 64-bit VM, normal klass
+  if (base_off % BytesPerLong != 0) {
+    assert(UseCompressedClassPointers, "");
+    if (is_array) {
+      // Exclude length to copy by 8 bytes words.
+      base_off += sizeof(int);
+    } else {
+      // Include klass to copy by 8 bytes words.
+      base_off = instanceOopDesc::klass_offset_in_bytes();
+    }
+    assert(base_off % BytesPerLong == 0, "expect 8 bytes alignment");
+  }
+  Node* src_base  = kit->basic_plus_adr(src,  base_off);
+  Node* dst_base = kit->basic_plus_adr(dst, base_off);
+
+  // Compute the length also, if needed:
+  Node* countx = size;
+  countx = kit->gvn().transform(new SubXNode(countx, kit->MakeConX(base_off)));
+  countx = kit->gvn().transform(new URShiftXNode(countx, kit->intcon(LogBytesPerLong) ));
+
+  const TypePtr* raw_adr_type = TypeRawPtr::BOTTOM;
+
+  ArrayCopyNode* ac = ArrayCopyNode::make(kit, false, src_base, NULL, dst_base, NULL, countx, false, false);
+  ac->set_clonebasic();
+  Node* n = kit->gvn().transform(ac);
+  if (n == ac) {
+    kit->set_predefined_output_for_runtime_call(ac, ac->in(TypeFunc::Memory), raw_adr_type);
+  } else {
+    kit->set_all_memory(n);
+  }
+}
+
+C2DecoratorSet C2BarrierSetCodeGen::fixup_decorators(C2DecoratorSet decorators) {
+  bool is_volatile = (decorators & C2_MO_VOLATILE) != 0;
+  bool is_acquire = (decorators & C2_MO_ACQUIRE) != 0;
+  bool is_release = (decorators & C2_MO_RELEASE) != 0;
+  bool is_relaxed = (decorators & C2_MO_RELAXED) != 0;
+  bool is_atomic = (decorators & C2_ACCESS_ATOMIC) != 0;
+
+  if (is_volatile) {
+    is_acquire = true;
+    is_release = true;
+  }
+
+  if (!is_acquire && !is_release) {
+    is_relaxed = true;
+  } else {
+    is_atomic = true;
+  }
+
+  // Some accesses require access atomicity for all types, notably longs and doubles.
+  // When AlwaysAtomicAccesses is enabled, all accesses are atomic.
+  is_atomic = is_atomic || AlwaysAtomicAccesses;
+
+  if (is_acquire) {
+    decorators = decorators | C2_MO_ACQUIRE;
+  }
+  if (is_release) {
+    decorators = decorators | C2_MO_RELEASE;
+  }
+  if (is_relaxed) {
+    decorators = decorators | C2_MO_RELAXED;
+  }
+  if (is_atomic) {
+    decorators = decorators | C2_ACCESS_ATOMIC;
+  }
+
+  return decorators;
+}