omptarget.h

//===-------- omptarget.h - Target independent OpenMP target RTL -- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Interface to be used by Clang during the codegen of a
// target region.
//
//===----------------------------------------------------------------------===//

#ifndef _OMPTARGET_H_
#define _OMPTARGET_H_

#include <deque>
#include <stddef.h>
#include <stdint.h>

#include <SourceInfo.h>

#define OFFLOAD_SUCCESS (0)
#define OFFLOAD_FAIL (~0)

#define OFFLOAD_DEVICE_DEFAULT -1

// Don't format out enums and structs.
// clang-format off

/// return flags of __tgt_target_XXX public APIs
enum __tgt_target_return_t : int {
  /// successful offload executed on a target device
  OMP_TGT_SUCCESS = 0,
  /// offload may not execute on the requested target device
  /// this scenario can be caused by the device not available or unsupported
  /// as described in the Execution Model in the specifcation
  /// this status may not be used for target device execution failure
  /// which should be handled internally in libomptarget
  OMP_TGT_FAIL = ~0
};

/// Data attributes for each data reference used in an OpenMP target region.
enum tgt_map_type {
  // No flags
  OMP_TGT_MAPTYPE_NONE            = 0x000,
  // copy data from host to device
  OMP_TGT_MAPTYPE_TO              = 0x001,
  // copy data from device to host
  OMP_TGT_MAPTYPE_FROM            = 0x002,
  // copy regardless of the reference count
  OMP_TGT_MAPTYPE_ALWAYS          = 0x004,
  // force unmapping of data
  OMP_TGT_MAPTYPE_DELETE          = 0x008,
  // map the pointer as well as the pointee
  OMP_TGT_MAPTYPE_PTR_AND_OBJ     = 0x010,
  // pass device base address to kernel
  OMP_TGT_MAPTYPE_TARGET_PARAM    = 0x020,
  // return base device address of mapped data
  OMP_TGT_MAPTYPE_RETURN_PARAM    = 0x040,
  // private variable - not mapped
  OMP_TGT_MAPTYPE_PRIVATE         = 0x080,
  // copy by value - not mapped
  OMP_TGT_MAPTYPE_LITERAL         = 0x100,
  // mapping is implicit
  OMP_TGT_MAPTYPE_IMPLICIT        = 0x200,
  // copy data to device
  OMP_TGT_MAPTYPE_CLOSE           = 0x400,
  // runtime error if not already allocated
  OMP_TGT_MAPTYPE_PRESENT         = 0x1000,
  // use a separate reference counter so that the data cannot be unmapped within
  // the structured region
  // This is an OpenMP extension for the sake of OpenACC support.
  OMP_TGT_MAPTYPE_OMPX_HOLD       = 0x2000,
  // descriptor for non-contiguous target-update
  OMP_TGT_MAPTYPE_NON_CONTIG      = 0x100000000000,
  // member of struct, member given by [16 MSBs] - 1
  OMP_TGT_MAPTYPE_MEMBER_OF       = 0xffff000000000000
};

enum OpenMPOffloadingDeclareTargetFlags {
  /// Mark the entry as having a 'link' attribute.
  OMP_DECLARE_TARGET_LINK = 0x01,
  /// Mark the entry as being a global constructor.
  OMP_DECLARE_TARGET_CTOR = 0x02,
  /// Mark the entry as being a global destructor.
  OMP_DECLARE_TARGET_DTOR = 0x04
};

enum OpenMPOffloadingRequiresDirFlags {
  /// flag undefined.
  OMP_REQ_UNDEFINED               = 0x000,
  /// no requires directive present.
  OMP_REQ_NONE                    = 0x001,
  /// reverse_offload clause.
  OMP_REQ_REVERSE_OFFLOAD         = 0x002,
  /// unified_address clause.
  OMP_REQ_UNIFIED_ADDRESS         = 0x004,
  /// unified_shared_memory clause.
  OMP_REQ_UNIFIED_SHARED_MEMORY   = 0x008,
  /// dynamic_allocators clause.
  OMP_REQ_DYNAMIC_ALLOCATORS      = 0x010
};

enum TargetAllocTy : int32_t {
  TARGET_ALLOC_DEVICE = 0,
  TARGET_ALLOC_HOST,
  TARGET_ALLOC_SHARED,
  TARGET_ALLOC_DEFAULT
};

/// This struct contains all of the arguments to a target kernel region launch.
struct __tgt_kernel_arguments {
  int32_t Version;    // Version of this struct for ABI compatibility.
  int32_t NumArgs;    // Number of arguments in each input pointer.
  void **ArgBasePtrs; // Base pointer of each argument (e.g. a struct).
  void **ArgPtrs;     // Pointer to the argument data.
  int64_t *ArgSizes;  // Size of the argument data in bytes.
  int64_t *ArgTypes;  // Type of the data (e.g. to / from).
  void **ArgNames;    // Name of the data for debugging, possibly null.
  void **ArgMappers;  // User-defined mappers, possibly null.
  int64_t Tripcount;  // Tripcount for the teams / distribute loop, 0 otherwise.
};
static_assert(sizeof(__tgt_kernel_arguments) == 64 ||
                  sizeof(__tgt_kernel_arguments) == 40,
              "Invalid struct size");

/// This struct is a record of an entry point or global. For a function
/// entry point the size is expected to be zero
struct __tgt_offload_entry {
  void *addr;   // Pointer to the offload entry info (function or global)
  char *name;   // Name of the function or global
  size_t size;  // Size of the entry info (0 if it is a function)
  int32_t flags; // Flags associated with the entry, e.g. 'link'.
  int32_t reserved; // Reserved, to be used by the runtime library.
};

/// This struct is a record of the device image information
struct __tgt_device_image {
  void *ImageStart;                  // Pointer to the target code start
  void *ImageEnd;                    // Pointer to the target code end
  __tgt_offload_entry *EntriesBegin; // Begin of table with all target entries
  __tgt_offload_entry *EntriesEnd;   // End of table (non inclusive)
};

/// This struct contains information about a given image.
struct __tgt_image_info {
  const char *Arch;
};

/// This struct is a record of all the host code that may be offloaded to a
/// target.
struct __tgt_bin_desc {
  int32_t NumDeviceImages;           // Number of device types supported
  __tgt_device_image *DeviceImages;  // Array of device images (1 per dev. type)
  __tgt_offload_entry *HostEntriesBegin; // Begin of table with all host entries
  __tgt_offload_entry *HostEntriesEnd;   // End of table (non inclusive)
};

/// This struct contains the offload entries identified by the target runtime
struct __tgt_target_table {
  __tgt_offload_entry *EntriesBegin; // Begin of the table with all the entries
  __tgt_offload_entry
      *EntriesEnd; // End of the table with all the entries (non inclusive)
};

// clang-format on

/// This struct contains information exchanged between different asynchronous
/// operations for device-dependent optimization and potential synchronization
struct __tgt_async_info {
  // A pointer to a queue-like structure where offloading operations are issued.
  // We assume to use this structure to do synchronization. In CUDA backend, it
  // is CUstream.
  void *Queue = nullptr;
};

struct DeviceTy;

/// The libomptarget wrapper around a __tgt_async_info object directly
/// associated with a libomptarget layer device. RAII semantics to avoid
/// mistakes.
class AsyncInfoTy {
  /// Locations we used in (potentially) asynchronous calls which should live
  /// as long as this AsyncInfoTy object.
  std::deque<void *> BufferLocations;

  __tgt_async_info AsyncInfo;
  DeviceTy &Device;

public:
  AsyncInfoTy(DeviceTy &Device) : Device(Device) {}
  ~AsyncInfoTy() { synchronize(); }

  /// Implicit conversion to the __tgt_async_info which is used in the
  /// plugin interface.
  operator __tgt_async_info *() { return &AsyncInfo; }

  /// Synchronize all pending actions.
  ///
  /// \returns OFFLOAD_FAIL or OFFLOAD_SUCCESS appropriately.
  int synchronize();

  /// Return a void* reference with a lifetime that is at least as long as this
  /// AsyncInfoTy object. The location can be used as intermediate buffer.
  void *&getVoidPtrLocation();
};

/// This struct is a record of non-contiguous information
struct __tgt_target_non_contig {
  uint64_t Offset;
  uint64_t Count;
  uint64_t Stride;
};

struct __tgt_device_info {
  void *Context = nullptr;
  void *Device = nullptr;
};

#ifdef __cplusplus
extern "C" {
#endif

int omp_get_num_devices(void);
int omp_get_device_num(void);
int omp_get_initial_device(void);
void *omp_target_alloc(size_t Size, int DeviceNum);
void omp_target_free(void *DevicePtr, int DeviceNum);
int omp_target_is_present(const void *Ptr, int DeviceNum);
int omp_target_memcpy(void *Dst, const void *Src, size_t Length,
                      size_t DstOffset, size_t SrcOffset, int DstDevice,
                      int SrcDevice);
int omp_target_memcpy_rect(void *Dst, const void *Src, size_t ElementSize,
                           int NumDims, const size_t *Volume,
                           const size_t *DstOffsets, const size_t *SrcOffsets,
                           const size_t *DstDimensions,
                           const size_t *SrcDimensions, int DstDevice,
                           int SrcDevice);
int omp_target_associate_ptr(const void *HostPtr, const void *DevicePtr,
                             size_t Size, size_t DeviceOffset, int DeviceNum);
int omp_target_disassociate_ptr(const void *HostPtr, int DeviceNum);

/// Explicit target memory allocators
/// Using the llvm_ prefix until they become part of the OpenMP standard.
void *llvm_omp_target_alloc_device(size_t Size, int DeviceNum);
void *llvm_omp_target_alloc_host(size_t Size, int DeviceNum);
void *llvm_omp_target_alloc_shared(size_t Size, int DeviceNum);

/// Dummy target so we have a symbol for generating host fallback.
void *llvm_omp_target_dynamic_shared_alloc();

/// add the clauses of the requires directives in a given file
void __tgt_register_requires(int64_t Flags);

/// adds a target shared library to the target execution image
void __tgt_register_lib(__tgt_bin_desc *Desc);

/// Initialize all RTLs at once
void __tgt_init_all_rtls();

/// removes a target shared library from the target execution image
void __tgt_unregister_lib(__tgt_bin_desc *Desc);

// creates the host to target data mapping, stores it in the
// libomptarget.so internal structure (an entry in a stack of data maps) and
// passes the data to the device;
void __tgt_target_data_begin(int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
                             void **Args, int64_t *ArgSizes, int64_t *ArgTypes);
void __tgt_target_data_begin_nowait(int64_t DeviceId, int32_t ArgNum,
                                    void **ArgsBase, void **Args,
                                    int64_t *ArgSizes, int64_t *ArgTypes,
                                    int32_t DepNum, void *DepList,
                                    int32_t NoAliasDepNum,
                                    void *NoAliasDepList);
void __tgt_target_data_begin_mapper(ident_t *Loc, int64_t DeviceId,
                                    int32_t ArgNum, void **ArgsBase,
                                    void **Args, int64_t *ArgSizes,
                                    int64_t *ArgTypes, map_var_info_t *ArgNames,
                                    void **ArgMappers);
void __tgt_target_data_begin_nowait_mapper(
    ident_t *Loc, int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
    void **Args, int64_t *ArgSizes, int64_t *ArgTypes, map_var_info_t *ArgNames,
    void **ArgMappers, int32_t DepNum, void *DepList, int32_t NoAliasDepNum,
    void *NoAliasDepList);

// passes data from the target, release target memory and destroys the
// host-target mapping (top entry from the stack of data maps) created by
// the last __tgt_target_data_begin
void __tgt_target_data_end(int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
                           void **Args, int64_t *ArgSizes, int64_t *ArgTypes);
void __tgt_target_data_end_nowait(int64_t DeviceId, int32_t ArgNum,
                                  void **ArgsBase, void **Args,
                                  int64_t *ArgSizes, int64_t *ArgTypes,
                                  int32_t DepNum, void *DepList,
                                  int32_t NoAliasDepNum, void *NoAliasDepList);
void __tgt_target_data_end_mapper(ident_t *Loc, int64_t DeviceId,
                                  int32_t ArgNum, void **ArgsBase, void **Args,
                                  int64_t *ArgSizes, int64_t *ArgTypes,
                                  map_var_info_t *ArgNames, void **ArgMappers);
void __tgt_target_data_end_nowait_mapper(
    ident_t *Loc, int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
    void **Args, int64_t *ArgSizes, int64_t *ArgTypes, map_var_info_t *ArgNames,
    void **ArgMappers, int32_t depNum, void *depList, int32_t NoAliasDepNum,
    void *NoAliasDepList);

/// passes data to/from the target
void __tgt_target_data_update(int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
                              void **Args, int64_t *ArgSizes,
                              int64_t *ArgTypes);
void __tgt_target_data_update_nowait(int64_t DeviceId, int32_t ArgNum,
                                     void **ArgsBase, void **Args,
                                     int64_t *ArgSizes, int64_t *ArgTypes,
                                     int32_t DepNum, void *DepList,
                                     int32_t NoAliasDepNum,
                                     void *NoAliasDepList);
void __tgt_target_data_update_mapper(ident_t *Loc, int64_t DeviceId,
                                     int32_t ArgNum, void **ArgsBase,
                                     void **Args, int64_t *ArgSizes,
                                     int64_t *ArgTypes,
                                     map_var_info_t *ArgNames,
                                     void **ArgMappers);
void __tgt_target_data_update_nowait_mapper(
    ident_t *Loc, int64_t DeviceId, int32_t ArgNum, void **ArgsBase,
    void **Args, int64_t *ArgSizes, int64_t *ArgTypes, map_var_info_t *ArgNames,
    void **ArgMappers, int32_t DepNum, void *DepList, int32_t NoAliasDepNum,
    void *NoAliasDepList);

// Performs the same actions as data_begin in case ArgNum is non-zero
// and initiates run of offloaded region on target platform; if ArgNum
// is non-zero after the region execution is done it also performs the
// same action as data_end above. The following types are used; this
// function returns 0 if it was able to transfer the execution to a
// target and an int different from zero otherwise.
int __tgt_target_kernel(ident_t *Loc, int64_t DeviceId, int32_t NumTeams,
                        int32_t ThreadLimit, void *HostPtr,
                        __tgt_kernel_arguments *Args);
int __tgt_target_kernel_nowait(ident_t *Loc, int64_t DeviceId, int32_t NumTeams,
                               int32_t ThreadLimit, void *HostPtr,
                               __tgt_kernel_arguments *Args, int32_t DepNum,
                               void *DepList, int32_t NoAliasDepNum,
                               void *NoAliasDepList);

void __tgt_set_info_flag(uint32_t);

int __tgt_print_device_info(int64_t DeviceId);
#ifdef __cplusplus
}
#endif

#ifdef __cplusplus
#define EXTERN extern "C"
#else
#define EXTERN extern
#endif

#endif // _OMPTARGET_H_