llvm/llvm/lib/Frontend/Offloading/OffloadWrapper.cpp

//===- OffloadWrapper.cpp ---------------------------------------*- 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
//
//===----------------------------------------------------------------------===//

#include "llvm/Frontend/Offloading/OffloadWrapper.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/BinaryFormat/Magic.h"
#include "llvm/Frontend/Offloading/Utility.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Object/OffloadBinary.h"
#include "llvm/Support/Error.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"

usingnamespacellvm;
usingnamespacellvm::offloading;

namespace {
/// Magic number that begins the section containing the CUDA fatbinary.
constexpr unsigned CudaFatMagic = …;
constexpr unsigned HIPFatMagic = …;

IntegerType *getSizeTTy(Module &M) { … }

// struct __tgt_device_image {
//   void *ImageStart;
//   void *ImageEnd;
//   __tgt_offload_entry *EntriesBegin;
//   __tgt_offload_entry *EntriesEnd;
// };
StructType *getDeviceImageTy(Module &M) { … }

PointerType *getDeviceImagePtrTy(Module &M) { … }

// struct __tgt_bin_desc {
//   int32_t NumDeviceImages;
//   __tgt_device_image *DeviceImages;
//   __tgt_offload_entry *HostEntriesBegin;
//   __tgt_offload_entry *HostEntriesEnd;
// };
StructType *getBinDescTy(Module &M) { … }

PointerType *getBinDescPtrTy(Module &M) { … }

/// Creates binary descriptor for the given device images. Binary descriptor
/// is an object that is passed to the offloading runtime at program startup
/// and it describes all device images available in the executable or shared
/// library. It is defined as follows
///
/// __attribute__((visibility("hidden")))
/// extern __tgt_offload_entry *__start_omp_offloading_entries;
/// __attribute__((visibility("hidden")))
/// extern __tgt_offload_entry *__stop_omp_offloading_entries;
///
/// static const char Image0[] = { <Bufs.front() contents> };
///  ...
/// static const char ImageN[] = { <Bufs.back() contents> };
///
/// static const __tgt_device_image Images[] = {
///   {
///     Image0,                            /*ImageStart*/
///     Image0 + sizeof(Image0),           /*ImageEnd*/
///     __start_omp_offloading_entries,    /*EntriesBegin*/
///     __stop_omp_offloading_entries      /*EntriesEnd*/
///   },
///   ...
///   {
///     ImageN,                            /*ImageStart*/
///     ImageN + sizeof(ImageN),           /*ImageEnd*/
///     __start_omp_offloading_entries,    /*EntriesBegin*/
///     __stop_omp_offloading_entries      /*EntriesEnd*/
///   }
/// };
///
/// static const __tgt_bin_desc BinDesc = {
///   sizeof(Images) / sizeof(Images[0]),  /*NumDeviceImages*/
///   Images,                              /*DeviceImages*/
///   __start_omp_offloading_entries,      /*HostEntriesBegin*/
///   __stop_omp_offloading_entries        /*HostEntriesEnd*/
/// };
///
/// Global variable that represents BinDesc is returned.
GlobalVariable *createBinDesc(Module &M, ArrayRef<ArrayRef<char>> Bufs,
                              EntryArrayTy EntryArray, StringRef Suffix,
                              bool Relocatable) { … }

Function *createUnregisterFunction(Module &M, GlobalVariable *BinDesc,
                                   StringRef Suffix) { … }

void createRegisterFunction(Module &M, GlobalVariable *BinDesc,
                            StringRef Suffix) { … }

// struct fatbin_wrapper {
//  int32_t magic;
//  int32_t version;
//  void *image;
//  void *reserved;
//};
StructType *getFatbinWrapperTy(Module &M) { … }

/// Embed the image \p Image into the module \p M so it can be found by the
/// runtime.
GlobalVariable *createFatbinDesc(Module &M, ArrayRef<char> Image, bool IsHIP,
                                 StringRef Suffix) { … }

/// Create the register globals function. We will iterate all of the offloading
/// entries stored at the begin / end symbols and register them according to
/// their type. This creates the following function in IR:
///
/// extern struct __tgt_offload_entry __start_cuda_offloading_entries;
/// extern struct __tgt_offload_entry __stop_cuda_offloading_entries;
///
/// extern void __cudaRegisterFunction(void **, void *, void *, void *, int,
///                                    void *, void *, void *, void *, int *);
/// extern void __cudaRegisterVar(void **, void *, void *, void *, int32_t,
///                               int64_t, int32_t, int32_t);
///
/// void __cudaRegisterTest(void **fatbinHandle) {
///   for (struct __tgt_offload_entry *entry = &__start_cuda_offloading_entries;
///        entry != &__stop_cuda_offloading_entries; ++entry) {
///     if (!entry->size)
///       __cudaRegisterFunction(fatbinHandle, entry->addr, entry->name,
///                              entry->name, -1, 0, 0, 0, 0, 0);
///     else
///       __cudaRegisterVar(fatbinHandle, entry->addr, entry->name, entry->name,
///                         0, entry->size, 0, 0);
///   }
/// }
Function *createRegisterGlobalsFunction(Module &M, bool IsHIP,
                                        EntryArrayTy EntryArray,
                                        StringRef Suffix,
                                        bool EmitSurfacesAndTextures) { … }

// Create the constructor and destructor to register the fatbinary with the CUDA
// runtime.
void createRegisterFatbinFunction(Module &M, GlobalVariable *FatbinDesc,
                                  bool IsHIP, EntryArrayTy EntryArray,
                                  StringRef Suffix,
                                  bool EmitSurfacesAndTextures) { … }
} // namespace

Error offloading::wrapOpenMPBinaries(Module &M, ArrayRef<ArrayRef<char>> Images,
                                     EntryArrayTy EntryArray,
                                     llvm::StringRef Suffix, bool Relocatable) { … }

Error offloading::wrapCudaBinary(Module &M, ArrayRef<char> Image,
                                 EntryArrayTy EntryArray,
                                 llvm::StringRef Suffix,
                                 bool EmitSurfacesAndTextures) { … }

Error offloading::wrapHIPBinary(Module &M, ArrayRef<char> Image,
                                EntryArrayTy EntryArray, llvm::StringRef Suffix,
                                bool EmitSurfacesAndTextures) { … }