Exemplo n.º 1
0
/// Fixup WeakForLinker linkages in \p TheModule based on summary analysis.
void llvm::thinLTOResolveWeakForLinkerModule(
    Module &TheModule, const GVSummaryMapTy &DefinedGlobals) {
  auto updateLinkage = [&](GlobalValue &GV) {
    if (!GlobalValue::isWeakForLinker(GV.getLinkage()))
      return;
    // See if the global summary analysis computed a new resolved linkage.
    const auto &GS = DefinedGlobals.find(GV.getGUID());
    if (GS == DefinedGlobals.end())
      return;
    auto NewLinkage = GS->second->linkage();
    if (NewLinkage == GV.getLinkage())
      return;
    DEBUG(dbgs() << "ODR fixing up linkage for `" << GV.getName() << "` from "
                 << GV.getLinkage() << " to " << NewLinkage << "\n");
    GV.setLinkage(NewLinkage);
  };

  // Process functions and global now
  for (auto &GV : TheModule)
    updateLinkage(GV);
  for (auto &GV : TheModule.globals())
    updateLinkage(GV);
  for (auto &GV : TheModule.aliases())
    updateLinkage(GV);
}
Exemplo n.º 2
0
/// Fixup WeakForLinker linkages in \p TheModule based on summary analysis.
void llvm::thinLTOResolveWeakForLinkerModule(
    Module &TheModule, const GVSummaryMapTy &DefinedGlobals) {
  auto updateLinkage = [&](GlobalValue &GV) {
    if (!GlobalValue::isWeakForLinker(GV.getLinkage()))
      return;
    // See if the global summary analysis computed a new resolved linkage.
    const auto &GS = DefinedGlobals.find(GV.getGUID());
    if (GS == DefinedGlobals.end())
      return;
    auto NewLinkage = GS->second->linkage();
    if (NewLinkage == GV.getLinkage())
      return;
    DEBUG(dbgs() << "ODR fixing up linkage for `" << GV.getName() << "` from "
                 << GV.getLinkage() << " to " << NewLinkage << "\n");
    GV.setLinkage(NewLinkage);
    // Remove functions converted to available_externally from comdats,
    // as this is a declaration for the linker, and will be dropped eventually.
    // It is illegal for comdats to contain declarations.
    auto *GO = dyn_cast_or_null<GlobalObject>(&GV);
    if (GO && GO->isDeclarationForLinker() && GO->hasComdat()) {
      assert(GO->hasAvailableExternallyLinkage() &&
             "Expected comdat on definition (possibly available external)");
      GO->setComdat(nullptr);
    }
  };

  // Process functions and global now
  for (auto &GV : TheModule)
    updateLinkage(GV);
  for (auto &GV : TheModule.globals())
    updateLinkage(GV);
  for (auto &GV : TheModule.aliases())
    updateLinkage(GV);
}
Exemplo n.º 3
0
Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
                       Module &Mod, ModuleSummaryIndex &CombinedIndex,
                       const FunctionImporter::ImportMapTy &ImportList,
                       const GVSummaryMapTy &DefinedGlobals,
                       MapVector<StringRef, MemoryBufferRef> &ModuleMap) {
  Expected<const Target *> TOrErr = initAndLookupTarget(Conf, Mod);
  if (!TOrErr)
    return TOrErr.takeError();

  std::unique_ptr<TargetMachine> TM =
      createTargetMachine(Conf, Mod.getTargetTriple(), *TOrErr);

  handleAsmUndefinedRefs(Mod, *TM);

  if (Conf.CodeGenOnly) {
    codegen(Conf, TM.get(), AddStream, Task, Mod);
    return Error::success();
  }

  if (Conf.PreOptModuleHook && !Conf.PreOptModuleHook(Task, Mod))
    return Error::success();

  renameModuleForThinLTO(Mod, CombinedIndex);

  thinLTOResolveWeakForLinkerModule(Mod, DefinedGlobals);

  if (Conf.PostPromoteModuleHook && !Conf.PostPromoteModuleHook(Task, Mod))
    return Error::success();

  if (!DefinedGlobals.empty())
    thinLTOInternalizeModule(Mod, DefinedGlobals);

  if (Conf.PostInternalizeModuleHook &&
      !Conf.PostInternalizeModuleHook(Task, Mod))
    return Error::success();

  auto ModuleLoader = [&](StringRef Identifier) {
    assert(Mod.getContext().isODRUniquingDebugTypes() &&
           "ODR Type uniquing should be enabled on the context");
    return std::move(getLazyBitcodeModule(ModuleMap[Identifier],
                                          Mod.getContext(),
                                          /*ShouldLazyLoadMetadata=*/true)
                         .get());
  };

  FunctionImporter Importer(CombinedIndex, ModuleLoader);
  if (Error Err = Importer.importFunctions(Mod, ImportList).takeError())
    return Err;

  if (Conf.PostImportModuleHook && !Conf.PostImportModuleHook(Task, Mod))
    return Error::success();

  if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLto=*/true))
    return Error::success();

  codegen(Conf, TM.get(), AddStream, Task, Mod);
  return Error::success();
}
Exemplo n.º 4
0
/// Run internalization on \p TheModule based on symmary analysis.
void llvm::thinLTOInternalizeModule(Module &TheModule,
                                    const GVSummaryMapTy &DefinedGlobals) {
  // Parse inline ASM and collect the list of symbols that are not defined in
  // the current module.
  StringSet<> AsmUndefinedRefs;
  ModuleSymbolTable::CollectAsmSymbols(
      Triple(TheModule.getTargetTriple()), TheModule.getModuleInlineAsm(),
      [&AsmUndefinedRefs](StringRef Name, object::BasicSymbolRef::Flags Flags) {
        if (Flags & object::BasicSymbolRef::SF_Undefined)
          AsmUndefinedRefs.insert(Name);
      });

  // Declare a callback for the internalize pass that will ask for every
  // candidate GlobalValue if it can be internalized or not.
  auto MustPreserveGV = [&](const GlobalValue &GV) -> bool {
    // Can't be internalized if referenced in inline asm.
    if (AsmUndefinedRefs.count(GV.getName()))
      return true;

    // Lookup the linkage recorded in the summaries during global analysis.
    const auto &GS = DefinedGlobals.find(GV.getGUID());
    GlobalValue::LinkageTypes Linkage;
    if (GS == DefinedGlobals.end()) {
      // Must have been promoted (possibly conservatively). Find original
      // name so that we can access the correct summary and see if it can
      // be internalized again.
      // FIXME: Eventually we should control promotion instead of promoting
      // and internalizing again.
      StringRef OrigName =
          ModuleSummaryIndex::getOriginalNameBeforePromote(GV.getName());
      std::string OrigId = GlobalValue::getGlobalIdentifier(
          OrigName, GlobalValue::InternalLinkage,
          TheModule.getSourceFileName());
      const auto &GS = DefinedGlobals.find(GlobalValue::getGUID(OrigId));
      if (GS == DefinedGlobals.end()) {
        // Also check the original non-promoted non-globalized name. In some
        // cases a preempted weak value is linked in as a local copy because
        // it is referenced by an alias (IRLinker::linkGlobalValueProto).
        // In that case, since it was originally not a local value, it was
        // recorded in the index using the original name.
        // FIXME: This may not be needed once PR27866 is fixed.
        const auto &GS = DefinedGlobals.find(GlobalValue::getGUID(OrigName));
        assert(GS != DefinedGlobals.end());
        Linkage = GS->second->linkage();
      } else {
        Linkage = GS->second->linkage();
      }
    } else
      Linkage = GS->second->linkage();
    return !GlobalValue::isLocalLinkage(Linkage);
  };

  // FIXME: See if we can just internalize directly here via linkage changes
  // based on the index, rather than invoking internalizeModule.
  llvm::internalizeModule(TheModule, MustPreserveGV);
}