//===----------- device.h - Target independent OpenMP target RTL ----------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Declarations for managing devices that are handled by RTL plugins.
//
//===----------------------------------------------------------------------===//

#ifndef _OMPTARGET_DEVICE_H
#define _OMPTARGET_DEVICE_H

#include <cassert>
#include <cstddef>
#include <list>
#include <map>
#include <mutex>
#include <set>
#include <vector>

// Forward declarations.
struct RTLInfoTy;
struct __tgt_bin_desc;
struct __tgt_target_table;
struct __tgt_async_info;

/// Map between host data and target data.
struct HostDataToTargetTy {
  uintptr_t HstPtrBase; // host info.
  uintptr_t HstPtrBegin;
  uintptr_t HstPtrEnd; // non-inclusive.

  uintptr_t TgtPtrBegin; // target info.

private:
  /// use mutable to allow modification via std::set iterator which is const.
  mutable uint64_t RefCount;
  static const uint64_t INFRefCount = ~(uint64_t)0;

public:
  HostDataToTargetTy(uintptr_t BP, uintptr_t B, uintptr_t E, uintptr_t TB,
      bool IsINF = false)
      : HstPtrBase(BP), HstPtrBegin(B), HstPtrEnd(E),
        TgtPtrBegin(TB), RefCount(IsINF ? INFRefCount : 1) {}

  uint64_t getRefCount() const {
    return RefCount;
  }

  uint64_t resetRefCount() const {
    if (RefCount != INFRefCount)
      RefCount = 1;

    return RefCount;
  }

  uint64_t incRefCount() const {
    if (RefCount != INFRefCount) {
      ++RefCount;
      assert(RefCount < INFRefCount && "refcount overflow");
    }

    return RefCount;
  }

  uint64_t decRefCount() const {
    if (RefCount != INFRefCount) {
      assert(RefCount > 0 && "refcount underflow");
      --RefCount;
    }

    return RefCount;
  }

  bool isRefCountInf() const {
    return RefCount == INFRefCount;
  }
};

typedef uintptr_t HstPtrBeginTy;
inline bool operator<(const HostDataToTargetTy &lhs, const HstPtrBeginTy &rhs) {
  return lhs.HstPtrBegin < rhs;
}
inline bool operator<(const HstPtrBeginTy &lhs, const HostDataToTargetTy &rhs) {
  return lhs < rhs.HstPtrBegin;
}
inline bool operator<(const HostDataToTargetTy &lhs,
                      const HostDataToTargetTy &rhs) {
  return lhs.HstPtrBegin < rhs.HstPtrBegin;
}

typedef std::set<HostDataToTargetTy, std::less<>> HostDataToTargetListTy;

struct LookupResult {
  struct {
    unsigned IsContained   : 1;
    unsigned ExtendsBefore : 1;
    unsigned ExtendsAfter  : 1;
  } Flags;

  HostDataToTargetListTy::iterator Entry;

  LookupResult() : Flags({0,0,0}), Entry() {}
};

/// Map for shadow pointers
struct ShadowPtrValTy {
  void *HstPtrVal;
  void *TgtPtrAddr;
  void *TgtPtrVal;
};
typedef std::map<void *, ShadowPtrValTy> ShadowPtrListTy;

///
struct PendingCtorDtorListsTy {
  std::list<void *> PendingCtors;
  std::list<void *> PendingDtors;
};
typedef std::map<__tgt_bin_desc *, PendingCtorDtorListsTy>
    PendingCtorsDtorsPerLibrary;

struct DeviceTy {
  int32_t DeviceID;
  RTLInfoTy *RTL;
  int32_t RTLDeviceID;

  bool IsInit;
  std::once_flag InitFlag;
  bool HasPendingGlobals;

  HostDataToTargetListTy HostDataToTargetMap;
  PendingCtorsDtorsPerLibrary PendingCtorsDtors;

  ShadowPtrListTy ShadowPtrMap;

  std::mutex DataMapMtx, PendingGlobalsMtx, ShadowMtx;

  // NOTE: Once libomp gains full target-task support, this state should be
  // moved into the target task in libomp.
  std::map<int32_t, uint64_t> LoopTripCnt;

  DeviceTy(RTLInfoTy *RTL)
      : DeviceID(-1), RTL(RTL), RTLDeviceID(-1), IsInit(false), InitFlag(),
        HasPendingGlobals(false), HostDataToTargetMap(), PendingCtorsDtors(),
        ShadowPtrMap(), DataMapMtx(), PendingGlobalsMtx(), ShadowMtx() {}

  // The existence of mutexes makes DeviceTy non-copyable. We need to
  // provide a copy constructor and an assignment operator explicitly.
  DeviceTy(const DeviceTy &d)
      : DeviceID(d.DeviceID), RTL(d.RTL), RTLDeviceID(d.RTLDeviceID),
        IsInit(d.IsInit), InitFlag(), HasPendingGlobals(d.HasPendingGlobals),
        HostDataToTargetMap(d.HostDataToTargetMap),
        PendingCtorsDtors(d.PendingCtorsDtors), ShadowPtrMap(d.ShadowPtrMap),
        DataMapMtx(), PendingGlobalsMtx(), ShadowMtx(),
        LoopTripCnt(d.LoopTripCnt) {}

  DeviceTy& operator=(const DeviceTy &d) {
    DeviceID = d.DeviceID;
    RTL = d.RTL;
    RTLDeviceID = d.RTLDeviceID;
    IsInit = d.IsInit;
    HasPendingGlobals = d.HasPendingGlobals;
    HostDataToTargetMap = d.HostDataToTargetMap;
    PendingCtorsDtors = d.PendingCtorsDtors;
    ShadowPtrMap = d.ShadowPtrMap;
    LoopTripCnt = d.LoopTripCnt;

    return *this;
  }

  // Return true if data can be copied to DstDevice directly
  bool isDataExchangable(const DeviceTy& DstDevice);

  uint64_t getMapEntryRefCnt(void *HstPtrBegin);
  LookupResult lookupMapping(void *HstPtrBegin, int64_t Size);
  void *getOrAllocTgtPtr(void *HstPtrBegin, void *HstPtrBase, int64_t Size,
      bool &IsNew, bool &IsHostPtr, bool IsImplicit, bool UpdateRefCount = true,
      bool HasCloseModifier = false);
  void *getTgtPtrBegin(void *HstPtrBegin, int64_t Size);
  void *getTgtPtrBegin(void *HstPtrBegin, int64_t Size, bool &IsLast,
      bool UpdateRefCount, bool &IsHostPtr);
  int deallocTgtPtr(void *TgtPtrBegin, int64_t Size, bool ForceDelete,
                    bool HasCloseModifier = false);
  int associatePtr(void *HstPtrBegin, void *TgtPtrBegin, int64_t Size);
  int disassociatePtr(void *HstPtrBegin);

  // calls to RTL
  int32_t initOnce();
  __tgt_target_table *load_binary(void *Img);

  // Data transfer. When AsyncInfoPtr is nullptr, the transfer will be
  // synchronous.
  // Copy data from host to device
  int32_t data_submit(void *TgtPtrBegin, void *HstPtrBegin, int64_t Size,
                      __tgt_async_info *AsyncInfoPtr);
  // Copy data from device back to host
  int32_t data_retrieve(void *HstPtrBegin, void *TgtPtrBegin, int64_t Size,
                        __tgt_async_info *AsyncInfoPtr);
  // Copy data from current device to destination device directly
  int32_t data_exchange(void *SrcPtr, DeviceTy DstDev, void *DstPtr,
                        int64_t Size, __tgt_async_info *AsyncInfoPtr);

  int32_t run_region(void *TgtEntryPtr, void **TgtVarsPtr,
                     ptrdiff_t *TgtOffsets, int32_t TgtVarsSize,
                     __tgt_async_info *AsyncInfoPtr);
  int32_t run_team_region(void *TgtEntryPtr, void **TgtVarsPtr,
                          ptrdiff_t *TgtOffsets, int32_t TgtVarsSize,
                          int32_t NumTeams, int32_t ThreadLimit,
                          uint64_t LoopTripCount,
                          __tgt_async_info *AsyncInfoPtr);

private:
  // Call to RTL
  void init(); // To be called only via DeviceTy::initOnce()
};

/// Map between Device ID (i.e. openmp device id) and its DeviceTy.
typedef std::vector<DeviceTy> DevicesTy;
extern DevicesTy Devices;

extern bool device_is_ready(int device_num);

#endif