/*
 * 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/c2_BarrierSetCodeGen.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;
  }

  LoadNode::ControlDependency dep = LoadNode::DependsOnlyOnTest;
  if (anonymous) {
    // To be valid, unsafe loads may depend on other conditions than
    // the one that guards them: pin the Load node
    Node* ctrl = kit->control();
    if (adr_type->isa_instptr()) {
      assert(adr_type->meet(TypePtr::NULL_PTR) != adr_type->remove_speculative(), "should be not null");
      intptr_t offset = Type::OffsetBot;
      AddPNode::Ideal_base_and_offset(adr, &kit->gvn(), offset);
      if (offset >= 0) {
        int s = Klass::layout_helper_size_in_bytes(adr_type->isa_instptr()->klass()->layout_helper());
        if (offset < s) {
          // Guaranteed to be a valid access, no need to pin it
          no_control = true;
        } else {
          dep = LoadNode::Pinned;
        }
      }
    }
  }

  // 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,
                        dep, 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_UNORDERED) != 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_UNORDERED) != 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();
    }
  }

  return load_store;
}

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();
    }
  }

  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);

  pin_atomic_op(kit, result, alias_idx);

#ifdef _LP64
  bool is_obj = bt == T_OBJECT || bt == T_ARRAY;
  if (is_obj && adr->bottom_type()->is_ptr_to_narrowoop()) {
    result = kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));
  }
#endif

  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);

  pin_atomic_op(kit, result, alias_idx);

  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_UNORDERED) != 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_UNORDERED;
  }
  if (is_atomic) {
    decorators = decorators | C2_ACCESS_ATOMIC;
  }

  return decorators;
}