tools/lto/lto.cpp

//===-lto.cpp - LLVM Link Time Optimizer ----------------------------------===//
//
// 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 Link Time Optimization library. This library is
// intended to be used by linker to optimize code at link time.
//
//===----------------------------------------------------------------------===//

#include "llvm-c/lto.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/CodeGen/CommandFlags.inc"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/LTO/legacy/LTOCodeGenerator.h"
#include "llvm/LTO/legacy/LTOModule.h"
#include "llvm/LTO/legacy/ThinLTOCodeGenerator.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/raw_ostream.h"

// extra command-line flags needed for LTOCodeGenerator
static cl::opt<char>
OptLevel("O",
         cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
                  "(default = '-O2')"),
         cl::Prefix,
         cl::ZeroOrMore,
         cl::init('2'));

static cl::opt<bool>
DisableInline("disable-inlining", cl::init(false),
  cl::desc("Do not run the inliner pass"));

static cl::opt<bool>
DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
  cl::desc("Do not run the GVN load PRE pass"));

static cl::opt<bool> DisableLTOVectorization(
    "disable-lto-vectorization", cl::init(false),
    cl::desc("Do not run loop or slp vectorization during LTO"));

static cl::opt<bool> EnableFreestanding(
    "lto-freestanding", cl::init(false),
    cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"));

#ifdef NDEBUG
static bool VerifyByDefault = false;
#else
static bool VerifyByDefault = true;
#endif

static cl::opt<bool> DisableVerify(
    "disable-llvm-verifier", cl::init(!VerifyByDefault),
    cl::desc("Don't run the LLVM verifier during the optimization pipeline"));

// Holds most recent error string.
// *** Not thread safe ***
static std::string sLastErrorString;

// Holds the initialization state of the LTO module.
// *** Not thread safe ***
static bool initialized = false;

// Holds the command-line option parsing state of the LTO module.
static bool parsedOptions = false;

static LLVMContext *LTOContext = nullptr;

struct LTOToolDiagnosticHandler : public DiagnosticHandler {
  bool handleDiagnostics(const DiagnosticInfo &DI) override {
    if (DI.getSeverity() != DS_Error) {
      DiagnosticPrinterRawOStream DP(errs());
      DI.print(DP);
      errs() << '\n';
      return true;
    }
    sLastErrorString = "";
    {
      raw_string_ostream Stream(sLastErrorString);
      DiagnosticPrinterRawOStream DP(Stream);
      DI.print(DP);
    }
    return true;
  }
};

// Initialize the configured targets if they have not been initialized.
static void lto_initialize() {
  if (!initialized) {
#ifdef _WIN32
    // Dialog box on crash disabling doesn't work across DLL boundaries, so do
    // it here.
    llvm::sys::DisableSystemDialogsOnCrash();
#endif

    InitializeAllTargetInfos();
    InitializeAllTargets();
    InitializeAllTargetMCs();
    InitializeAllAsmParsers();
    InitializeAllAsmPrinters();
    InitializeAllDisassemblers();

    static LLVMContext Context;
    LTOContext = &Context;
    LTOContext->setDiagnosticHandler(
        llvm::make_unique<LTOToolDiagnosticHandler>(), true);
    initialized = true;
  }
}

namespace {

static void handleLibLTODiagnostic(lto_codegen_diagnostic_severity_t Severity,
                                   const char *Msg, void *) {
  sLastErrorString = Msg;
}

// This derived class owns the native object file. This helps implement the
// libLTO API semantics, which require that the code generator owns the object
// file.
struct LibLTOCodeGenerator : LTOCodeGenerator {
  LibLTOCodeGenerator() : LTOCodeGenerator(*LTOContext) { init(); }
  LibLTOCodeGenerator(std::unique_ptr<LLVMContext> Context)
      : LTOCodeGenerator(*Context), OwnedContext(std::move(Context)) {
    init();
  }

  // Reset the module first in case MergedModule is created in OwnedContext.
  // Module must be destructed before its context gets destructed.
  ~LibLTOCodeGenerator() { resetMergedModule(); }

  void init() { setDiagnosticHandler(handleLibLTODiagnostic, nullptr); }

  std::unique_ptr<MemoryBuffer> NativeObjectFile;
  std::unique_ptr<LLVMContext> OwnedContext;
};

}

DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LibLTOCodeGenerator, lto_code_gen_t)
DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ThinLTOCodeGenerator, thinlto_code_gen_t)
DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LTOModule, lto_module_t)

// Convert the subtarget features into a string to pass to LTOCodeGenerator.
static void lto_add_attrs(lto_code_gen_t cg) {
  LTOCodeGenerator *CG = unwrap(cg);
  if (MAttrs.size()) {
    std::string attrs;
    for (unsigned i = 0; i < MAttrs.size(); ++i) {
      if (i > 0)
        attrs.append(",");
      attrs.append(MAttrs[i]);
    }

    CG->setAttr(attrs);
  }

  if (OptLevel < '0' || OptLevel > '3')
    report_fatal_error("Optimization level must be between 0 and 3");
  CG->setOptLevel(OptLevel - '0');
  CG->setFreestanding(EnableFreestanding);
}

extern const char* lto_get_version() {
  return LTOCodeGenerator::getVersionString();
}

const char* lto_get_error_message() {
  return sLastErrorString.c_str();
}

bool lto_module_is_object_file(const char* path) {
  return LTOModule::isBitcodeFile(StringRef(path));
}

bool lto_module_is_object_file_for_target(const char* path,
                                          const char* target_triplet_prefix) {
  ErrorOr<std::unique_ptr<MemoryBuffer>> Buffer = MemoryBuffer::getFile(path);
  if (!Buffer)
    return false;
  return LTOModule::isBitcodeForTarget(Buffer->get(),
                                       StringRef(target_triplet_prefix));
}

bool lto_module_has_objc_category(const void *mem, size_t length) {
  std::unique_ptr<MemoryBuffer> Buffer(LTOModule::makeBuffer(mem, length));
  if (!Buffer)
    return false;
  LLVMContext Ctx;
  ErrorOr<bool> Result = expectedToErrorOrAndEmitErrors(
      Ctx, llvm::isBitcodeContainingObjCCategory(*Buffer));
  return Result && *Result;
}

bool lto_module_is_object_file_in_memory(const void* mem, size_t length) {
  return LTOModule::isBitcodeFile(mem, length);
}

bool
lto_module_is_object_file_in_memory_for_target(const void* mem,
                                            size_t length,
                                            const char* target_triplet_prefix) {
  std::unique_ptr<MemoryBuffer> buffer(LTOModule::makeBuffer(mem, length));
  if (!buffer)
    return false;
  return LTOModule::isBitcodeForTarget(buffer.get(),
                                       StringRef(target_triplet_prefix));
}

lto_module_t lto_module_create(const char* path) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
  ErrorOr<std::unique_ptr<LTOModule>> M =
      LTOModule::createFromFile(*LTOContext, StringRef(path), Options);
  if (!M)
    return nullptr;
  return wrap(M->release());
}

lto_module_t lto_module_create_from_fd(int fd, const char *path, size_t size) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
  ErrorOr<std::unique_ptr<LTOModule>> M = LTOModule::createFromOpenFile(
      *LTOContext, fd, StringRef(path), size, Options);
  if (!M)
    return nullptr;
  return wrap(M->release());
}

lto_module_t lto_module_create_from_fd_at_offset(int fd, const char *path,
                                                 size_t file_size,
                                                 size_t map_size,
                                                 off_t offset) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
  ErrorOr<std::unique_ptr<LTOModule>> M = LTOModule::createFromOpenFileSlice(
      *LTOContext, fd, StringRef(path), map_size, offset, Options);
  if (!M)
    return nullptr;
  return wrap(M->release());
}

lto_module_t lto_module_create_from_memory(const void* mem, size_t length) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
  ErrorOr<std::unique_ptr<LTOModule>> M =
      LTOModule::createFromBuffer(*LTOContext, mem, length, Options);
  if (!M)
    return nullptr;
  return wrap(M->release());
}

lto_module_t lto_module_create_from_memory_with_path(const void* mem,
                                                     size_t length,
                                                     const char *path) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
  ErrorOr<std::unique_ptr<LTOModule>> M = LTOModule::createFromBuffer(
      *LTOContext, mem, length, Options, StringRef(path));
  if (!M)
    return nullptr;
  return wrap(M->release());
}

lto_module_t lto_module_create_in_local_context(const void *mem, size_t length,
                                                const char *path) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();

  // Create a local context. Ownership will be transferred to LTOModule.
  std::unique_ptr<LLVMContext> Context = llvm::make_unique<LLVMContext>();
  Context->setDiagnosticHandler(llvm::make_unique<LTOToolDiagnosticHandler>(),
                                true);

  ErrorOr<std::unique_ptr<LTOModule>> M = LTOModule::createInLocalContext(
      std::move(Context), mem, length, Options, StringRef(path));
  if (!M)
    return nullptr;
  return wrap(M->release());
}

lto_module_t lto_module_create_in_codegen_context(const void *mem,
                                                  size_t length,
                                                  const char *path,
                                                  lto_code_gen_t cg) {
  lto_initialize();
  llvm::TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
  ErrorOr<std::unique_ptr<LTOModule>> M = LTOModule::createFromBuffer(
      unwrap(cg)->getContext(), mem, length, Options, StringRef(path));
  return wrap(M->release());
}

void lto_module_dispose(lto_module_t mod) { delete unwrap(mod); }

const char* lto_module_get_target_triple(lto_module_t mod) {
  return unwrap(mod)->getTargetTriple().c_str();
}

void lto_module_set_target_triple(lto_module_t mod, const char *triple) {
  return unwrap(mod)->setTargetTriple(StringRef(triple));
}

unsigned int lto_module_get_num_symbols(lto_module_t mod) {
  return unwrap(mod)->getSymbolCount();
}

const char* lto_module_get_symbol_name(lto_module_t mod, unsigned int index) {
  return unwrap(mod)->getSymbolName(index).data();
}

lto_symbol_attributes lto_module_get_symbol_attribute(lto_module_t mod,
                                                      unsigned int index) {
  return unwrap(mod)->getSymbolAttributes(index);
}

const char* lto_module_get_linkeropts(lto_module_t mod) {
  return unwrap(mod)->getLinkerOpts().data();
}

void lto_codegen_set_diagnostic_handler(lto_code_gen_t cg,
                                        lto_diagnostic_handler_t diag_handler,
                                        void *ctxt) {
  unwrap(cg)->setDiagnosticHandler(diag_handler, ctxt);
}

static lto_code_gen_t createCodeGen(bool InLocalContext) {
  lto_initialize();

  TargetOptions Options = InitTargetOptionsFromCodeGenFlags();

  LibLTOCodeGenerator *CodeGen =
      InLocalContext ? new LibLTOCodeGenerator(make_unique<LLVMContext>())
                     : new LibLTOCodeGenerator();
  CodeGen->setTargetOptions(Options);
  return wrap(CodeGen);
}

lto_code_gen_t lto_codegen_create(void) {
  return createCodeGen(/* InLocalContext */ false);
}

lto_code_gen_t lto_codegen_create_in_local_context(void) {
  return createCodeGen(/* InLocalContext */ true);
}

void lto_codegen_dispose(lto_code_gen_t cg) { delete unwrap(cg); }

bool lto_codegen_add_module(lto_code_gen_t cg, lto_module_t mod) {
  return !unwrap(cg)->addModule(unwrap(mod));
}

void lto_codegen_set_module(lto_code_gen_t cg, lto_module_t mod) {
  unwrap(cg)->setModule(std::unique_ptr<LTOModule>(unwrap(mod)));
}

bool lto_codegen_set_debug_model(lto_code_gen_t cg, lto_debug_model debug) {
  unwrap(cg)->setDebugInfo(debug);
  return false;
}

bool lto_codegen_set_pic_model(lto_code_gen_t cg, lto_codegen_model model) {
  switch (model) {
  case LTO_CODEGEN_PIC_MODEL_STATIC:
    unwrap(cg)->setCodePICModel(Reloc::Static);
    return false;
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
    unwrap(cg)->setCodePICModel(Reloc::PIC_);
    return false;
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
    unwrap(cg)->setCodePICModel(Reloc::DynamicNoPIC);
    return false;
  case LTO_CODEGEN_PIC_MODEL_DEFAULT:
    unwrap(cg)->setCodePICModel(None);
    return false;
  }
  sLastErrorString = "Unknown PIC model";
  return true;
}

void lto_codegen_set_cpu(lto_code_gen_t cg, const char *cpu) {
  return unwrap(cg)->setCpu(cpu);
}

void lto_codegen_set_assembler_path(lto_code_gen_t cg, const char *path) {
  // In here only for backwards compatibility. We use MC now.
}

void lto_codegen_set_assembler_args(lto_code_gen_t cg, const char **args,
                                    int nargs) {
  // In here only for backwards compatibility. We use MC now.
}

void lto_codegen_add_must_preserve_symbol(lto_code_gen_t cg,
                                          const char *symbol) {
  unwrap(cg)->addMustPreserveSymbol(symbol);
}

static void maybeParseOptions(lto_code_gen_t cg) {
  if (!parsedOptions) {
    unwrap(cg)->parseCodeGenDebugOptions();
    lto_add_attrs(cg);
    parsedOptions = true;
  }
}

bool lto_codegen_write_merged_modules(lto_code_gen_t cg, const char *path) {
  maybeParseOptions(cg);
  return !unwrap(cg)->writeMergedModules(path);
}

const void *lto_codegen_compile(lto_code_gen_t cg, size_t *length) {
  maybeParseOptions(cg);
  LibLTOCodeGenerator *CG = unwrap(cg);
  CG->NativeObjectFile =
      CG->compile(DisableVerify, DisableInline, DisableGVNLoadPRE,
                  DisableLTOVectorization);
  if (!CG->NativeObjectFile)
    return nullptr;
  *length = CG->NativeObjectFile->getBufferSize();
  return CG->NativeObjectFile->getBufferStart();
}

bool lto_codegen_optimize(lto_code_gen_t cg) {
  maybeParseOptions(cg);
  return !unwrap(cg)->optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
                               DisableLTOVectorization);
}

const void *lto_codegen_compile_optimized(lto_code_gen_t cg, size_t *length) {
  maybeParseOptions(cg);
  LibLTOCodeGenerator *CG = unwrap(cg);
  CG->NativeObjectFile = CG->compileOptimized();
  if (!CG->NativeObjectFile)
    return nullptr;
  *length = CG->NativeObjectFile->getBufferSize();
  return CG->NativeObjectFile->getBufferStart();
}

bool lto_codegen_compile_to_file(lto_code_gen_t cg, const char **name) {
  maybeParseOptions(cg);
  return !unwrap(cg)->compile_to_file(
      name, DisableVerify, DisableInline, DisableGVNLoadPRE,
      DisableLTOVectorization);
}

void lto_codegen_debug_options(lto_code_gen_t cg, const char *opt) {
  unwrap(cg)->setCodeGenDebugOptions(opt);
}

unsigned int lto_api_version() { return LTO_API_VERSION; }

void lto_codegen_set_should_internalize(lto_code_gen_t cg,
                                        bool ShouldInternalize) {
  unwrap(cg)->setShouldInternalize(ShouldInternalize);
}

void lto_codegen_set_should_embed_uselists(lto_code_gen_t cg,
                                           lto_bool_t ShouldEmbedUselists) {
  unwrap(cg)->setShouldEmbedUselists(ShouldEmbedUselists);
}

// ThinLTO API below

thinlto_code_gen_t thinlto_create_codegen(void) {
  lto_initialize();
  ThinLTOCodeGenerator *CodeGen = new ThinLTOCodeGenerator();
  CodeGen->setTargetOptions(InitTargetOptionsFromCodeGenFlags());
  CodeGen->setFreestanding(EnableFreestanding);

  if (OptLevel.getNumOccurrences()) {
    if (OptLevel < '0' || OptLevel > '3')
      report_fatal_error("Optimization level must be between 0 and 3");
    CodeGen->setOptLevel(OptLevel - '0');
    switch (OptLevel) {
    case '0':
      CodeGen->setCodeGenOptLevel(CodeGenOpt::None);
      break;
    case '1':
      CodeGen->setCodeGenOptLevel(CodeGenOpt::Less);
      break;
    case '2':
      CodeGen->setCodeGenOptLevel(CodeGenOpt::Default);
      break;
    case '3':
      CodeGen->setCodeGenOptLevel(CodeGenOpt::Aggressive);
      break;
    }
  }
  return wrap(CodeGen);
}

void thinlto_codegen_dispose(thinlto_code_gen_t cg) { delete unwrap(cg); }

void thinlto_codegen_add_module(thinlto_code_gen_t cg, const char *Identifier,
                                const char *Data, int Length) {
  unwrap(cg)->addModule(Identifier, StringRef(Data, Length));
}

void thinlto_codegen_process(thinlto_code_gen_t cg) { unwrap(cg)->run(); }

unsigned int thinlto_module_get_num_objects(thinlto_code_gen_t cg) {
  return unwrap(cg)->getProducedBinaries().size();
}
LTOObjectBuffer thinlto_module_get_object(thinlto_code_gen_t cg,
                                          unsigned int index) {
  assert(index < unwrap(cg)->getProducedBinaries().size() && "Index overflow");
  auto &MemBuffer = unwrap(cg)->getProducedBinaries()[index];
  return LTOObjectBuffer{MemBuffer->getBufferStart(),
                         MemBuffer->getBufferSize()};
}

unsigned int thinlto_module_get_num_object_files(thinlto_code_gen_t cg) {
  return unwrap(cg)->getProducedBinaryFiles().size();
}
const char *thinlto_module_get_object_file(thinlto_code_gen_t cg,
                                           unsigned int index) {
  assert(index < unwrap(cg)->getProducedBinaryFiles().size() &&
         "Index overflow");
  return unwrap(cg)->getProducedBinaryFiles()[index].c_str();
}

void thinlto_codegen_disable_codegen(thinlto_code_gen_t cg,
                                     lto_bool_t disable) {
  unwrap(cg)->disableCodeGen(disable);
}

void thinlto_codegen_set_codegen_only(thinlto_code_gen_t cg,
                                      lto_bool_t CodeGenOnly) {
  unwrap(cg)->setCodeGenOnly(CodeGenOnly);
}

void thinlto_debug_options(const char *const *options, int number) {
  // if options were requested, set them
  if (number && options) {
    std::vector<const char *> CodegenArgv(1, "libLTO");
    for (auto Arg : ArrayRef<const char *>(options, number))
      CodegenArgv.push_back(Arg);
    cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
  }
}

lto_bool_t lto_module_is_thinlto(lto_module_t mod) {
  return unwrap(mod)->isThinLTO();
}

void thinlto_codegen_add_must_preserve_symbol(thinlto_code_gen_t cg,
                                              const char *Name, int Length) {
  unwrap(cg)->preserveSymbol(StringRef(Name, Length));
}

void thinlto_codegen_add_cross_referenced_symbol(thinlto_code_gen_t cg,
                                                 const char *Name, int Length) {
  unwrap(cg)->crossReferenceSymbol(StringRef(Name, Length));
}

void thinlto_codegen_set_cpu(thinlto_code_gen_t cg, const char *cpu) {
  return unwrap(cg)->setCpu(cpu);
}

void thinlto_codegen_set_cache_dir(thinlto_code_gen_t cg,
                                   const char *cache_dir) {
  return unwrap(cg)->setCacheDir(cache_dir);
}

void thinlto_codegen_set_cache_pruning_interval(thinlto_code_gen_t cg,
                                                int interval) {
  return unwrap(cg)->setCachePruningInterval(interval);
}

void thinlto_codegen_set_cache_entry_expiration(thinlto_code_gen_t cg,
                                                unsigned expiration) {
  return unwrap(cg)->setCacheEntryExpiration(expiration);
}

void thinlto_codegen_set_final_cache_size_relative_to_available_space(
    thinlto_code_gen_t cg, unsigned Percentage) {
  return unwrap(cg)->setMaxCacheSizeRelativeToAvailableSpace(Percentage);
}

void thinlto_codegen_set_cache_size_bytes(
    thinlto_code_gen_t cg, unsigned MaxSizeBytes) {
  return unwrap(cg)->setCacheMaxSizeBytes(MaxSizeBytes);
}

void thinlto_codegen_set_cache_size_megabytes(
    thinlto_code_gen_t cg, unsigned MaxSizeMegabytes) {
  uint64_t MaxSizeBytes = MaxSizeMegabytes;
  MaxSizeBytes *= 1024 * 1024;
  return unwrap(cg)->setCacheMaxSizeBytes(MaxSizeBytes);
}

void thinlto_codegen_set_cache_size_files(
    thinlto_code_gen_t cg, unsigned MaxSizeFiles) {
  return unwrap(cg)->setCacheMaxSizeFiles(MaxSizeFiles);
}

void thinlto_codegen_set_savetemps_dir(thinlto_code_gen_t cg,
                                       const char *save_temps_dir) {
  return unwrap(cg)->setSaveTempsDir(save_temps_dir);
}

void thinlto_set_generated_objects_dir(thinlto_code_gen_t cg,
                                       const char *save_temps_dir) {
  unwrap(cg)->setGeneratedObjectsDirectory(save_temps_dir);
}

lto_bool_t thinlto_codegen_set_pic_model(thinlto_code_gen_t cg,
                                         lto_codegen_model model) {
  switch (model) {
  case LTO_CODEGEN_PIC_MODEL_STATIC:
    unwrap(cg)->setCodePICModel(Reloc::Static);
    return false;
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
    unwrap(cg)->setCodePICModel(Reloc::PIC_);
    return false;
  case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
    unwrap(cg)->setCodePICModel(Reloc::DynamicNoPIC);
    return false;
  case LTO_CODEGEN_PIC_MODEL_DEFAULT:
    unwrap(cg)->setCodePICModel(None);
    return false;
  }
  sLastErrorString = "Unknown PIC model";
  return true;
}