Coverage Report

Created: 2020-09-19 12:23

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/tools/clang-offload-wrapper/ClangOffloadWrapper.cpp
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//===-- clang-offload-wrapper/ClangOffloadWrapper.cpp -----------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// Implementation of the offload wrapper tool. It takes offload target binaries
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/// as input and creates wrapper bitcode file containing target binaries
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/// packaged as data. Wrapper bitcode also includes initialization code which
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/// registers target binaries in offloading runtime at program startup.
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///
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//===----------------------------------------------------------------------===//
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#include "clang/Basic/Version.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/Bitcode/BitcodeWriter.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Errc.h"
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#include "llvm/Support/Error.h"
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#include "llvm/Support/ErrorOr.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/Signals.h"
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#include "llvm/Support/ToolOutputFile.h"
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#include "llvm/Support/WithColor.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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#include <cassert>
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#include <cstdint>
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using namespace llvm;
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static cl::opt<bool> Help("h", cl::desc("Alias for -help"), cl::Hidden);
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// Mark all our options with this category, everything else (except for -version
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// and -help) will be hidden.
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static cl::OptionCategory
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    ClangOffloadWrapperCategory("clang-offload-wrapper options");
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static cl::opt<std::string> Output("o", cl::Required,
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                                   cl::desc("Output filename"),
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                                   cl::value_desc("filename"),
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                                   cl::cat(ClangOffloadWrapperCategory));
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static cl::list<std::string> Inputs(cl::Positional, cl::OneOrMore,
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                                    cl::desc("<input files>"),
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                                    cl::cat(ClangOffloadWrapperCategory));
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static cl::opt<std::string>
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    Target("target", cl::Required,
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           cl::desc("Target triple for the output module"),
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           cl::value_desc("triple"), cl::cat(ClangOffloadWrapperCategory));
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namespace {
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class BinaryWrapper {
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  LLVMContext C;
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  Module M;
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  StructType *EntryTy = nullptr;
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  StructType *ImageTy = nullptr;
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  StructType *DescTy = nullptr;
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private:
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  IntegerType *getSizeTTy() {
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    switch (M.getDataLayout().getPointerTypeSize(Type::getInt8PtrTy(C))) {
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0
    case 4u:
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0
      return Type::getInt32Ty(C);
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3
    case 8u:
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      return Type::getInt64Ty(C);
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0
    }
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    llvm_unreachable("unsupported pointer type size");
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0
  }
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  // struct __tgt_offload_entry {
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  //   void *addr;
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  //   char *name;
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  //   size_t size;
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  //   int32_t flags;
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  //   int32_t reserved;
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  // };
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  StructType *getEntryTy() {
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    if (!EntryTy)
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      EntryTy = StructType::create("__tgt_offload_entry", Type::getInt8PtrTy(C),
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                                   Type::getInt8PtrTy(C), getSizeTTy(),
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                                   Type::getInt32Ty(C), Type::getInt32Ty(C));
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    return EntryTy;
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  }
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  PointerType *getEntryPtrTy() { return PointerType::getUnqual(getEntryTy()); }
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  // struct __tgt_device_image {
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  //   void *ImageStart;
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  //   void *ImageEnd;
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  //   __tgt_offload_entry *EntriesBegin;
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  //   __tgt_offload_entry *EntriesEnd;
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  // };
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  StructType *getDeviceImageTy() {
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    if (!ImageTy)
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      ImageTy = StructType::create("__tgt_device_image", Type::getInt8PtrTy(C),
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                                   Type::getInt8PtrTy(C), getEntryPtrTy(),
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                                   getEntryPtrTy());
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    return ImageTy;
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  }
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  PointerType *getDeviceImagePtrTy() {
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    return PointerType::getUnqual(getDeviceImageTy());
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  }
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  // struct __tgt_bin_desc {
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  //   int32_t NumDeviceImages;
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  //   __tgt_device_image *DeviceImages;
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  //   __tgt_offload_entry *HostEntriesBegin;
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  //   __tgt_offload_entry *HostEntriesEnd;
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  // };
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  StructType *getBinDescTy() {
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    if (!DescTy)
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      DescTy = StructType::create("__tgt_bin_desc", Type::getInt32Ty(C),
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                                  getDeviceImagePtrTy(), getEntryPtrTy(),
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                                  getEntryPtrTy());
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    return DescTy;
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  }
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  PointerType *getBinDescPtrTy() {
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    return PointerType::getUnqual(getBinDescTy());
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  }
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  /// Creates binary descriptor for the given device images. Binary descriptor
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  /// is an object that is passed to the offloading runtime at program startup
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  /// and it describes all device images available in the executable or shared
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  /// library. It is defined as follows
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  ///
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  /// __attribute__((visibility("hidden")))
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  /// extern __tgt_offload_entry *__start_omp_offloading_entries;
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  /// __attribute__((visibility("hidden")))
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  /// extern __tgt_offload_entry *__stop_omp_offloading_entries;
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  ///
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  /// static const char Image0[] = { <Bufs.front() contents> };
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  ///  ...
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  /// static const char ImageN[] = { <Bufs.back() contents> };
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  ///
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  /// static const __tgt_device_image Images[] = {
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  ///   {
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  ///     Image0,                            /*ImageStart*/
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  ///     Image0 + sizeof(Image0),           /*ImageEnd*/
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  ///     __start_omp_offloading_entries,    /*EntriesBegin*/
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  ///     __stop_omp_offloading_entries      /*EntriesEnd*/
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  ///   },
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  ///   ...
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  ///   {
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  ///     ImageN,                            /*ImageStart*/
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  ///     ImageN + sizeof(ImageN),           /*ImageEnd*/
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  ///     __start_omp_offloading_entries,    /*EntriesBegin*/
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  ///     __stop_omp_offloading_entries      /*EntriesEnd*/
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  ///   }
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  /// };
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  ///
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  /// static const __tgt_bin_desc BinDesc = {
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  ///   sizeof(Images) / sizeof(Images[0]),  /*NumDeviceImages*/
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  ///   Images,                              /*DeviceImages*/
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  ///   __start_omp_offloading_entries,      /*HostEntriesBegin*/
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  ///   __stop_omp_offloading_entries        /*HostEntriesEnd*/
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  /// };
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  ///
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  /// Global variable that represents BinDesc is returned.
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  GlobalVariable *createBinDesc(ArrayRef<ArrayRef<char>> Bufs) {
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    // Create external begin/end symbols for the offload entries table.
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    auto *EntriesB = new GlobalVariable(
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        M, getEntryTy(), /*isConstant*/ true, GlobalValue::ExternalLinkage,
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        /*Initializer*/ nullptr, "__start_omp_offloading_entries");
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    EntriesB->setVisibility(GlobalValue::HiddenVisibility);
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    auto *EntriesE = new GlobalVariable(
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        M, getEntryTy(), /*isConstant*/ true, GlobalValue::ExternalLinkage,
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        /*Initializer*/ nullptr, "__stop_omp_offloading_entries");
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    EntriesE->setVisibility(GlobalValue::HiddenVisibility);
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1
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    // We assume that external begin/end symbols that we have created above will
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    // be defined by the linker. But linker will do that only if linker inputs
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    // have section with "omp_offloading_entries" name which is not guaranteed.
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    // So, we just create dummy zero sized object in the offload entries section
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    // to force linker to define those symbols.
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    auto *DummyInit =
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        ConstantAggregateZero::get(ArrayType::get(getEntryTy(), 0u));
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    auto *DummyEntry = new GlobalVariable(
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        M, DummyInit->getType(), true, GlobalVariable::ExternalLinkage,
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        DummyInit, "__dummy.omp_offloading.entry");
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    DummyEntry->setSection("omp_offloading_entries");
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    DummyEntry->setVisibility(GlobalValue::HiddenVisibility);
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1
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    auto *Zero = ConstantInt::get(getSizeTTy(), 0u);
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    Constant *ZeroZero[] = {Zero, Zero};
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1
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    // Create initializer for the images array.
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    SmallVector<Constant *, 4u> ImagesInits;
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    ImagesInits.reserve(Bufs.size());
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    for (ArrayRef<char> Buf : Bufs) {
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      auto *Data = ConstantDataArray::get(C, Buf);
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      auto *Image = new GlobalVariable(M, Data->getType(), /*isConstant*/ true,
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                                       GlobalVariable::InternalLinkage, Data,
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                                       ".omp_offloading.device_image");
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      Image->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
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      auto *Size = ConstantInt::get(getSizeTTy(), Buf.size());
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      Constant *ZeroSize[] = {Zero, Size};
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      auto *ImageB = ConstantExpr::getGetElementPtr(Image->getValueType(),
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                                                    Image, ZeroZero);
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      auto *ImageE = ConstantExpr::getGetElementPtr(Image->getValueType(),
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                                                    Image, ZeroSize);
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      ImagesInits.push_back(ConstantStruct::get(getDeviceImageTy(), ImageB,
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                                                ImageE, EntriesB, EntriesE));
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    }
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    // Then create images array.
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    auto *ImagesData = ConstantArray::get(
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        ArrayType::get(getDeviceImageTy(), ImagesInits.size()), ImagesInits);
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    auto *Images =
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        new GlobalVariable(M, ImagesData->getType(), /*isConstant*/ true,
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                           GlobalValue::InternalLinkage, ImagesData,
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                           ".omp_offloading.device_images");
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    Images->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
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    auto *ImagesB = ConstantExpr::getGetElementPtr(Images->getValueType(),
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                                                   Images, ZeroZero);
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1
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    // And finally create the binary descriptor object.
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    auto *DescInit = ConstantStruct::get(
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        getBinDescTy(),
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        ConstantInt::get(Type::getInt32Ty(C), ImagesInits.size()), ImagesB,
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        EntriesB, EntriesE);
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    return new GlobalVariable(M, DescInit->getType(), /*isConstant*/ true,
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                              GlobalValue::InternalLinkage, DescInit,
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                              ".omp_offloading.descriptor");
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  }
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  void createRegisterFunction(GlobalVariable *BinDesc) {
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    auto *FuncTy = FunctionType::get(Type::getVoidTy(C), /*isVarArg*/ false);
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    auto *Func = Function::Create(FuncTy, GlobalValue::InternalLinkage,
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                                  ".omp_offloading.descriptor_reg", &M);
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    Func->setSection(".text.startup");
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    // Get __tgt_register_lib function declaration.
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    auto *RegFuncTy = FunctionType::get(Type::getVoidTy(C), getBinDescPtrTy(),
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                                        /*isVarArg*/ false);
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    FunctionCallee RegFuncC =
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        M.getOrInsertFunction("__tgt_register_lib", RegFuncTy);
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    // Construct function body
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    IRBuilder<> Builder(BasicBlock::Create(C, "entry", Func));
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    Builder.CreateCall(RegFuncC, BinDesc);
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    Builder.CreateRetVoid();
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1
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    // Add this function to constructors.
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    // Set priority to 1 so that __tgt_register_lib is executed AFTER
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    // __tgt_register_requires (we want to know what requirements have been
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    // asked for before we load a libomptarget plugin so that by the time the
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    // plugin is loaded it can report how many devices there are which can
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    // satisfy these requirements).
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    appendToGlobalCtors(M, Func, /*Priority*/ 1);
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  }
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  void createUnregisterFunction(GlobalVariable *BinDesc) {
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    auto *FuncTy = FunctionType::get(Type::getVoidTy(C), /*isVarArg*/ false);
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    auto *Func = Function::Create(FuncTy, GlobalValue::InternalLinkage,
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                                  ".omp_offloading.descriptor_unreg", &M);
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    Func->setSection(".text.startup");
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    // Get __tgt_unregister_lib function declaration.
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    auto *UnRegFuncTy = FunctionType::get(Type::getVoidTy(C), getBinDescPtrTy(),
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                                          /*isVarArg*/ false);
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    FunctionCallee UnRegFuncC =
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        M.getOrInsertFunction("__tgt_unregister_lib", UnRegFuncTy);
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    // Construct function body
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    IRBuilder<> Builder(BasicBlock::Create(C, "entry", Func));
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    Builder.CreateCall(UnRegFuncC, BinDesc);
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    Builder.CreateRetVoid();
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1
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    // Add this function to global destructors.
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    // Match priority of __tgt_register_lib
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    appendToGlobalDtors(M, Func, /*Priority*/ 1);
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  }
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public:
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  BinaryWrapper(StringRef Target) : M("offload.wrapper.object", C) {
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    M.setTargetTriple(Target);
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  }
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  const Module &wrapBinaries(ArrayRef<ArrayRef<char>> Binaries) {
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    GlobalVariable *Desc = createBinDesc(Binaries);
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    assert(Desc && "no binary descriptor");
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    createRegisterFunction(Desc);
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    createUnregisterFunction(Desc);
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    return M;
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  }
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};
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} // anonymous namespace
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2
int main(int argc, const char **argv) {
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  sys::PrintStackTraceOnErrorSignal(argv[0]);
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  cl::HideUnrelatedOptions(ClangOffloadWrapperCategory);
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  cl::SetVersionPrinter([](raw_ostream &OS) {
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    OS << clang::getClangToolFullVersion("clang-offload-wrapper") << '\n';
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  });
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  cl::ParseCommandLineOptions(
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      argc, argv,
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      "A tool to create a wrapper bitcode for offload target binaries. Takes "
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      "offload\ntarget binaries as input and produces bitcode file containing "
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      "target binaries packaged\nas data and initialization code which "
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      "registers target binaries in offload runtime.\n");
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2
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  if (Help) {
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    cl::PrintHelpMessage();
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    return 0;
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0
  }
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  auto reportError = [argv](Error E) {
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0
    logAllUnhandledErrors(std::move(E), WithColor::error(errs(), argv[0]));
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0
  };
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2
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2
  if (Triple(Target).getArch() == Triple::UnknownArch) {
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0
    reportError(createStringError(
336
0
        errc::invalid_argument, "'" + Target + "': unsupported target triple"));
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    return 1;
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0
  }
339
2
340
  // Read device binaries.
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2
  SmallVector<std::unique_ptr<MemoryBuffer>, 4u> Buffers;
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2
  SmallVector<ArrayRef<char>, 4u> Images;
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  Buffers.reserve(Inputs.size());
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  Images.reserve(Inputs.size());
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1
  for (const std::string &File : Inputs) {
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1
    ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
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1
        MemoryBuffer::getFileOrSTDIN(File);
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1
    if (!BufOrErr) {
349
0
      reportError(createFileError(File, BufOrErr.getError()));
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0
      return 1;
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0
    }
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    const std::unique_ptr<MemoryBuffer> &Buf =
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        Buffers.emplace_back(std::move(*BufOrErr));
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    Images.emplace_back(Buf->getBufferStart(), Buf->getBufferSize());
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1
  }
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2
357
  // Create the output file to write the resulting bitcode to.
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  std::error_code EC;
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  ToolOutputFile Out(Output, EC, sys::fs::OF_None);
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2
  if (EC) {
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0
    reportError(createFileError(Output, EC));
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    return 1;
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0
  }
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2
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  // Create a wrapper for device binaries and write its bitcode to the file.
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  WriteBitcodeToFile(BinaryWrapper(Target).wrapBinaries(
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                         makeArrayRef(Images.data(), Images.size())),
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                     Out.os());
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  if (Out.os().has_error()) {
370
0
    reportError(createFileError(Output, Out.os().error()));
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    return 1;
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0
  }
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2
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  // Success.
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  Out.keep();
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  return 0;
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2
}