/*

 * Copyright (c) 2017, 2018, 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.

 *

 */

#ifndef SHARE_VM_RUNTIME_ACCESS_INLINE_HPP

#define SHARE_VM_RUNTIME_ACCESS_INLINE_HPP

#include "gc/shared/barrierSet.inline.hpp"

#include "metaprogramming/conditional.hpp"

#include "metaprogramming/isFloatingPoint.hpp"

#include "metaprogramming/isIntegral.hpp"

#include "metaprogramming/isPointer.hpp"

#include "metaprogramming/isVolatile.hpp"

#include "oops/access.hpp"

#include "oops/accessBackend.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/orderAccess.inline.hpp"

// This file outlines the template pipeline of accesses going through the Access

// API. There are essentially 5 steps for each access.

// * Step 1: Set default decorators and decay types. This step gets rid of CV qualifiers

//           and sets default decorators to sensible values.

// * Step 2: Reduce types. This step makes sure there is only a single T type and not

//           multiple types. The P type of the address and T type of the value must

//           match.

// * Step 3: Pre-runtime dispatch. This step checks whether a runtime call can be

//           avoided, and in that case avoids it (calling raw accesses or

//           primitive accesses in a build that does not require primitive GC barriers)

// * Step 4: Runtime-dispatch. This step performs a runtime dispatch to the corresponding

//           BarrierSet::AccessBarrier accessor that attaches GC-required barriers

//           to the access.

// * Step 5: Post-runtime dispatch. This step now casts previously unknown types such

//           as the address type of an oop on the heap (is it oop* or narrowOop*) to

//           the appropriate type. It also splits sufficiently orthogonal accesses into

//           different functions, such as whether the access involves oops or primitives

//           and whether the access is performed on the heap or outside. Then the

//           appropriate BarrierSet::AccessBarrier is called to perform the access.

namespace AccessInternal {

  // Step 5: Post-runtime dispatch.

  // This class is the last step before calling the BarrierSet::AccessBarrier.

  // Here we make sure to figure out types that were not known prior to the

  // runtime dispatch, such as whether an oop on the heap is oop or narrowOop.

  // We also split orthogonal barriers such as handling primitives vs oops

  // and on-heap vs off-heap into different calls to the barrier set.

  template <class GCBarrierType, BarrierType type, DecoratorSet decorators>

  struct PostRuntimeDispatch: public AllStatic { };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_STORE, decorators>: public AllStatic {

    template <typename T>

    static void access_barrier(void* addr, T value) {

      GCBarrierType::store_in_heap(reinterpret_cast<T*>(addr), value);

    }

    static void oop_access_barrier(void* addr, oop value) {

      typedef typename HeapOopType<decorators>::type OopType;

      if (HasDecorator<decorators, IN_HEAP>::value) {

        GCBarrierType::oop_store_in_heap(reinterpret_cast<OopType*>(addr), value);

      } else {

        GCBarrierType::oop_store_not_in_heap(reinterpret_cast<OopType*>(addr), value);

      }

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_LOAD, decorators>: public AllStatic {

    template <typename T>

    static T access_barrier(void* addr) {

      return GCBarrierType::load_in_heap(reinterpret_cast<T*>(addr));

    }

    static oop oop_access_barrier(void* addr) {

      typedef typename HeapOopType<decorators>::type OopType;

      if (HasDecorator<decorators, IN_HEAP>::value) {

        return GCBarrierType::oop_load_in_heap(reinterpret_cast<OopType*>(addr));

      } else {

        return GCBarrierType::oop_load_not_in_heap(reinterpret_cast<OopType*>(addr));

      }

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_ATOMIC_XCHG, decorators>: public AllStatic {

    template <typename T>

    static T access_barrier(T new_value, void* addr) {

      return GCBarrierType::atomic_xchg_in_heap(new_value, reinterpret_cast<T*>(addr));

    }

    static oop oop_access_barrier(oop new_value, void* addr) {

      typedef typename HeapOopType<decorators>::type OopType;

      if (HasDecorator<decorators, IN_HEAP>::value) {

        return GCBarrierType::oop_atomic_xchg_in_heap(new_value, reinterpret_cast<OopType*>(addr));

      } else {

        return GCBarrierType::oop_atomic_xchg_not_in_heap(new_value, reinterpret_cast<OopType*>(addr));

      }

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_ATOMIC_CMPXCHG, decorators>: public AllStatic {

    template <typename T>

    static T access_barrier(T new_value, void* addr, T compare_value) {

      return GCBarrierType::atomic_cmpxchg_in_heap(new_value, reinterpret_cast<T*>(addr), compare_value);

    }

    static oop oop_access_barrier(oop new_value, void* addr, oop compare_value) {

      typedef typename HeapOopType<decorators>::type OopType;

      if (HasDecorator<decorators, IN_HEAP>::value) {

        return GCBarrierType::oop_atomic_cmpxchg_in_heap(new_value, reinterpret_cast<OopType*>(addr), compare_value);

      } else {

        return GCBarrierType::oop_atomic_cmpxchg_not_in_heap(new_value, reinterpret_cast<OopType*>(addr), compare_value);

      }

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_ARRAYCOPY, decorators>: public AllStatic {

    template <typename T>

    static bool access_barrier(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length) {

      return GCBarrierType::arraycopy_in_heap(src_obj, dst_obj, src, dst, length);

    }

    template <typename T>

    static bool oop_access_barrier(arrayOop src_obj, arrayOop dst_obj, T* src, T* dst, size_t length) {

      typedef typename HeapOopType<decorators>::type OopType;

      return GCBarrierType::oop_arraycopy_in_heap(src_obj, dst_obj,

                                                  reinterpret_cast<OopType*>(src),

                                                  reinterpret_cast<OopType*>(dst), length);

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_STORE_AT, decorators>: public AllStatic {

    template <typename T>

    static void access_barrier(oop base, ptrdiff_t offset, T value) {

      GCBarrierType::store_in_heap_at(base, offset, value);

    }

    static void oop_access_barrier(oop base, ptrdiff_t offset, oop value) {

      GCBarrierType::oop_store_in_heap_at(base, offset, value);

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_LOAD_AT, decorators>: public AllStatic {

    template <typename T>

    static T access_barrier(oop base, ptrdiff_t offset) {

      return GCBarrierType::template load_in_heap_at<T>(base, offset);

    }

    static oop oop_access_barrier(oop base, ptrdiff_t offset) {

      return GCBarrierType::oop_load_in_heap_at(base, offset);

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_ATOMIC_XCHG_AT, decorators>: public AllStatic {

    template <typename T>

    static T access_barrier(T new_value, oop base, ptrdiff_t offset) {

      return GCBarrierType::atomic_xchg_in_heap_at(new_value, base, offset);

    }

    static oop oop_access_barrier(oop new_value, oop base, ptrdiff_t offset) {

      return GCBarrierType::oop_atomic_xchg_in_heap_at(new_value, base, offset);

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_ATOMIC_CMPXCHG_AT, decorators>: public AllStatic {

    template <typename T>

    static T access_barrier(T new_value, oop base, ptrdiff_t offset, T compare_value) {

      return GCBarrierType::atomic_cmpxchg_in_heap_at(new_value, base, offset, compare_value);

    }

    static oop oop_access_barrier(oop new_value, oop base, ptrdiff_t offset, oop compare_value) {

      return GCBarrierType::oop_atomic_cmpxchg_in_heap_at(new_value, base, offset, compare_value);

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_CLONE, decorators>: public AllStatic {

    static void access_barrier(oop src, oop dst, size_t size) {

      GCBarrierType::clone_in_heap(src, dst, size);

    }

  };

  template <class GCBarrierType, DecoratorSet decorators>

  struct PostRuntimeDispatch<GCBarrierType, BARRIER_RESOLVE, decorators>: public AllStatic {

    static oop access_barrier(oop obj) {

      return GCBarrierType::resolve(obj);

    }

  };

  // Resolving accessors with barriers from the barrier set happens in two steps.

  // 1. Expand paths with runtime-decorators, e.g. is UseCompressedOops on or off.

  // 2. Expand paths for each BarrierSet available in the system.

  template <DecoratorSet decorators, typename FunctionPointerT, BarrierType barrier_type>

  struct BarrierResolver: public AllStatic {

    template <DecoratorSet ds>

    static typename EnableIf<

      HasDecorator<ds, INTERNAL_VALUE_IS_OOP>::value,

      FunctionPointerT>::type

    resolve_barrier_gc() {

      BarrierSet* bs = BarrierSet::barrier_set();

      assert(bs != NULL, "GC barriers invoked before BarrierSet is set");

      switch (bs->kind()) {

#define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name)                    \

        case BarrierSet::bs_name: {                                     \

          return PostRuntimeDispatch<typename BarrierSet::GetType<BarrierSet::bs_name>::type:: \

            AccessBarrier<ds>, barrier_type, ds>::oop_access_barrier; \

        }                                                               \

        break;

        FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)

#undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE

      default:

        fatal("BarrierSet AccessBarrier resolving not implemented");

        return NULL;

      };

    }

    template <DecoratorSet ds>

    static typename EnableIf<

      !HasDecorator<ds, INTERNAL_VALUE_IS_OOP>::value,

      FunctionPointerT>::type

    resolve_barrier_gc() {

      BarrierSet* bs = BarrierSet::barrier_set();

      assert(bs != NULL, "GC barriers invoked before BarrierSet is set");

      switch (bs->kind()) {

#define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name)                    \

        case BarrierSet::bs_name: {                                       \

          return PostRuntimeDispatch<typename BarrierSet::GetType<BarrierSet::bs_name>::type:: \

            AccessBarrier<ds>, barrier_type, ds>::access_barrier; \

        }                                                                 \

        break;

        FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)

#undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE

      default:

        fatal("BarrierSet AccessBarrier resolving not implemented");

        return NULL;

      };

    }

    static FunctionPointerT resolve_barrier_rt() {

      if (UseCompressedOops) {

        const DecoratorSet expanded_decorators = decorators | INTERNAL_RT_USE_COMPRESSED_OOPS;

        return resolve_barrier_gc<expanded_decorators>();

      } else {

        return resolve_barrier_gc<decorators>();

      }

    }

    static FunctionPointerT resolve_barrier() {

      return resolve_barrier_rt();

    }

  };

  // Step 4: Runtime dispatch

  // The RuntimeDispatch class is responsible for performing a runtime dispatch of the

  // accessor. This is required when the access either depends on whether compressed oops

  // is being used, or it depends on which GC implementation was chosen (e.g. requires GC

  // barriers). The way it works is that a function pointer initially pointing to an

  // accessor resolution function gets called for each access. Upon first invocation,

  // it resolves which accessor to be used in future invocations and patches the

  // function pointer to this new accessor.

  template <DecoratorSet decorators, typename T, BarrierType type>

  struct RuntimeDispatch: AllStatic {};

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_STORE>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_STORE>::type func_t;

    static func_t _store_func;

    static void store_init(void* addr, T value) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_STORE>::resolve_barrier();

      _store_func = function;

      function(addr, value);

    }

    static inline void store(void* addr, T value) {

      _store_func(addr, value);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_STORE_AT>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_STORE_AT>::type func_t;

    static func_t _store_at_func;

    static void store_at_init(oop base, ptrdiff_t offset, T value) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_STORE_AT>::resolve_barrier();

      _store_at_func = function;

      function(base, offset, value);

    }

    static inline void store_at(oop base, ptrdiff_t offset, T value) {

      _store_at_func(base, offset, value);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_LOAD>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_LOAD>::type func_t;

    static func_t _load_func;

    static T load_init(void* addr) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_LOAD>::resolve_barrier();

      _load_func = function;

      return function(addr);

    }

    static inline T load(void* addr) {

      return _load_func(addr);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_LOAD_AT>::type func_t;

    static func_t _load_at_func;

    static T load_at_init(oop base, ptrdiff_t offset) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_LOAD_AT>::resolve_barrier();

      _load_at_func = function;

      return function(base, offset);

    }

    static inline T load_at(oop base, ptrdiff_t offset) {

      return _load_at_func(base, offset);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG>::type func_t;

    static func_t _atomic_cmpxchg_func;

    static T atomic_cmpxchg_init(T new_value, void* addr, T compare_value) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_ATOMIC_CMPXCHG>::resolve_barrier();

      _atomic_cmpxchg_func = function;

      return function(new_value, addr, compare_value);

    }

    static inline T atomic_cmpxchg(T new_value, void* addr, T compare_value) {

      return _atomic_cmpxchg_func(new_value, addr, compare_value);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::type func_t;

    static func_t _atomic_cmpxchg_at_func;

    static T atomic_cmpxchg_at_init(T new_value, oop base, ptrdiff_t offset, T compare_value) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_ATOMIC_CMPXCHG_AT>::resolve_barrier();

      _atomic_cmpxchg_at_func = function;

      return function(new_value, base, offset, compare_value);

    }

    static inline T atomic_cmpxchg_at(T new_value, oop base, ptrdiff_t offset, T compare_value) {

      return _atomic_cmpxchg_at_func(new_value, base, offset, compare_value);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG>::type func_t;

    static func_t _atomic_xchg_func;

    static T atomic_xchg_init(T new_value, void* addr) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_ATOMIC_XCHG>::resolve_barrier();

      _atomic_xchg_func = function;

      return function(new_value, addr);

    }

    static inline T atomic_xchg(T new_value, void* addr) {

      return _atomic_xchg_func(new_value, addr);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG_AT>::type func_t;

    static func_t _atomic_xchg_at_func;

    static T atomic_xchg_at_init(T new_value, oop base, ptrdiff_t offset) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_ATOMIC_XCHG_AT>::resolve_barrier();

      _atomic_xchg_at_func = function;

      return function(new_value, base, offset);

    }

    static inline T atomic_xchg_at(T new_value, oop base, ptrdiff_t offset) {

      return _atomic_xchg_at_func(new_value, base, offset);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_ARRAYCOPY>::type func_t;

    static func_t _arraycopy_func;

    static bool arraycopy_init(arrayOop src_obj, arrayOop dst_obj, T *src, T* dst, size_t length) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_ARRAYCOPY>::resolve_barrier();

      _arraycopy_func = function;

      return function(src_obj, dst_obj, src, dst, length);

    }

    static inline bool arraycopy(arrayOop src_obj, arrayOop dst_obj, T *src, T* dst, size_t length) {

      return _arraycopy_func(src_obj, dst_obj, src, dst, length);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_CLONE>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_CLONE>::type func_t;

    static func_t _clone_func;

    static void clone_init(oop src, oop dst, size_t size) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_CLONE>::resolve_barrier();

      _clone_func = function;

      function(src, dst, size);

    }

    static inline void clone(oop src, oop dst, size_t size) {

      _clone_func(src, dst, size);

    }

  };

  template <DecoratorSet decorators, typename T>

  struct RuntimeDispatch<decorators, T, BARRIER_RESOLVE>: AllStatic {

    typedef typename AccessFunction<decorators, T, BARRIER_RESOLVE>::type func_t;

    static func_t _resolve_func;

    static oop resolve_init(oop obj) {

      func_t function = BarrierResolver<decorators, func_t, BARRIER_RESOLVE>::resolve_barrier();

      _resolve_func = function;

      return function(obj);

    }

    static inline oop resolve(oop obj) {

      return _resolve_func(obj);

    }

  };

  // Initialize the function pointers to point to the resolving function.

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_STORE>::type

  RuntimeDispatch<decorators, T, BARRIER_STORE>::_store_func = &store_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_STORE_AT>::type

  RuntimeDispatch<decorators, T, BARRIER_STORE_AT>::_store_at_func = &store_at_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_LOAD>::type

  RuntimeDispatch<decorators, T, BARRIER_LOAD>::_load_func = &load_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_LOAD_AT>::type

  RuntimeDispatch<decorators, T, BARRIER_LOAD_AT>::_load_at_func = &load_at_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG>::type

  RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG>::_atomic_cmpxchg_func = &atomic_cmpxchg_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::type

  RuntimeDispatch<decorators, T, BARRIER_ATOMIC_CMPXCHG_AT>::_atomic_cmpxchg_at_func = &atomic_cmpxchg_at_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG>::type

  RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG>::_atomic_xchg_func = &atomic_xchg_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_ATOMIC_XCHG_AT>::type

  RuntimeDispatch<decorators, T, BARRIER_ATOMIC_XCHG_AT>::_atomic_xchg_at_func = &atomic_xchg_at_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_ARRAYCOPY>::type

  RuntimeDispatch<decorators, T, BARRIER_ARRAYCOPY>::_arraycopy_func = &arraycopy_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_CLONE>::type

  RuntimeDispatch<decorators, T, BARRIER_CLONE>::_clone_func = &clone_init;

  template <DecoratorSet decorators, typename T>

  typename AccessFunction<decorators, T, BARRIER_RESOLVE>::type

  RuntimeDispatch<decorators, T, BARRIER_RESOLVE>::_resolve_func = &resolve_init;

  // Step 3: Pre-runtime dispatching.

  // The PreRuntimeDispatch class is responsible for filtering the barrier strength

  // decorators. That is, for AS_RAW, it hardwires the accesses without a runtime

  // dispatch point. Otherwise it goes through a runtime check if hardwiring was

  // not possible.

  struct PreRuntimeDispatch: AllStatic {

    template<DecoratorSet decorators>

    struct CanHardwireRaw: public IntegralConstant<

      bool,

      !HasDecorator<decorators, INTERNAL_VALUE_IS_OOP>::value || // primitive access

      !HasDecorator<decorators, INTERNAL_CONVERT_COMPRESSED_OOP>::value || // don't care about compressed oops (oop* address)

      HasDecorator<decorators, INTERNAL_RT_USE_COMPRESSED_OOPS>::value> // we can infer we use compressed oops (narrowOop* address)

    {};