llvm/llvm/lib/LTO/LTOBackend.cpp

//===-LTOBackend.cpp - LLVM Link Time Optimizer Backend -------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the "backend" phase of LTO, i.e. it performs
// optimization and code generation on a loaded module. It is generally used
// internally by the LTO class but can also be used independently, for example
// to implement a standalone ThinLTO backend.
//
//===----------------------------------------------------------------------===//

#include "llvm/LTO/LTOBackend.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CGSCCPassManager.h"
#include "llvm/Analysis/ModuleSummaryAnalysis.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/IR/LLVMRemarkStreamer.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Verifier.h"
#include "llvm/LTO/LTO.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Object/ModuleSymbolTable.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/PassPlugin.h"
#include "llvm/Passes/StandardInstrumentations.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/ThreadPool.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/TargetParser/SubtargetFeature.h"
#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
#include "llvm/Transforms/Scalar/LoopPassManager.h"
#include "llvm/Transforms/Utils/FunctionImportUtils.h"
#include "llvm/Transforms/Utils/SplitModule.h"
#include <optional>

usingnamespacellvm;
usingnamespacelto;

#define DEBUG_TYPE …

enum class LTOBitcodeEmbedding { … };

static cl::opt<LTOBitcodeEmbedding> EmbedBitcode(
    "lto-embed-bitcode", cl::init(LTOBitcodeEmbedding::DoNotEmbed),
    cl::values(clEnumValN(LTOBitcodeEmbedding::DoNotEmbed, "none",
                          "Do not embed"),
               clEnumValN(LTOBitcodeEmbedding::EmbedOptimized, "optimized",
                          "Embed after all optimization passes"),
               clEnumValN(LTOBitcodeEmbedding::EmbedPostMergePreOptimized,
                          "post-merge-pre-opt",
                          "Embed post merge, but before optimizations")),
    cl::desc("Embed LLVM bitcode in object files produced by LTO"));

static cl::opt<bool> ThinLTOAssumeMerged(
    "thinlto-assume-merged", cl::init(false),
    cl::desc("Assume the input has already undergone ThinLTO function "
             "importing and the other pre-optimization pipeline changes."));

namespace llvm {
extern cl::opt<bool> NoPGOWarnMismatch;
}

[[noreturn]] static void reportOpenError(StringRef Path, Twine Msg) { … }

Error Config::addSaveTemps(std::string OutputFileName, bool UseInputModulePath,
                           const DenseSet<StringRef> &SaveTempsArgs) { … }

#define HANDLE_EXTENSION …
#include "llvm/Support/Extension.def"

static void RegisterPassPlugins(ArrayRef<std::string> PassPlugins,
                                PassBuilder &PB) { … }

static std::unique_ptr<TargetMachine>
createTargetMachine(const Config &Conf, const Target *TheTarget, Module &M) { … }

static void runNewPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM,
                           unsigned OptLevel, bool IsThinLTO,
                           ModuleSummaryIndex *ExportSummary,
                           const ModuleSummaryIndex *ImportSummary) { … }

bool lto::opt(const Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
              bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
              const ModuleSummaryIndex *ImportSummary,
              const std::vector<uint8_t> &CmdArgs) { … }

static void codegen(const Config &Conf, TargetMachine *TM,
                    AddStreamFn AddStream, unsigned Task, Module &Mod,
                    const ModuleSummaryIndex &CombinedIndex) { … }

static void splitCodeGen(const Config &C, TargetMachine *TM,
                         AddStreamFn AddStream,
                         unsigned ParallelCodeGenParallelismLevel, Module &Mod,
                         const ModuleSummaryIndex &CombinedIndex) { … }

static Expected<const Target *> initAndLookupTarget(const Config &C,
                                                    Module &Mod) { … }

Error lto::finalizeOptimizationRemarks(
    std::unique_ptr<ToolOutputFile> DiagOutputFile) { … }

Error lto::backend(const Config &C, AddStreamFn AddStream,
                   unsigned ParallelCodeGenParallelismLevel, Module &Mod,
                   ModuleSummaryIndex &CombinedIndex) { … }

static void dropDeadSymbols(Module &Mod, const GVSummaryMapTy &DefinedGlobals,
                            const ModuleSummaryIndex &Index) { … }

Error lto::thinBackend(const Config &Conf, unsigned Task, AddStreamFn AddStream,
                       Module &Mod, const ModuleSummaryIndex &CombinedIndex,
                       const FunctionImporter::ImportMapTy &ImportList,
                       const GVSummaryMapTy &DefinedGlobals,
                       MapVector<StringRef, BitcodeModule> *ModuleMap,
                       const std::vector<uint8_t> &CmdArgs) { … }

BitcodeModule *lto::findThinLTOModule(MutableArrayRef<BitcodeModule> BMs) { … }

Expected<BitcodeModule> lto::findThinLTOModule(MemoryBufferRef MBRef) { … }

bool lto::initImportList(const Module &M,
                         const ModuleSummaryIndex &CombinedIndex,
                         FunctionImporter::ImportMapTy &ImportList) { … }