X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=tools%2Fgold%2Fgold-plugin.cpp;h=77e4b83223c6d597dcea0cba261698e8d6b9131d;hp=95f7e32a611fbfa0ec9ceba3c99aa7b5b4a69c65;hb=31b8ab0fa67c63ddd067f1cac6d21d61c16afc27;hpb=2bfef929c01800ec65de1f681f9af1bfed14ea81

diff --git a/tools/gold/gold-plugin.cpp b/tools/gold/gold-plugin.cpp
index 95f7e32a611..77e4b83223c 100644
--- a/tools/gold/gold-plugin.cpp
+++ b/tools/gold/gold-plugin.cpp
@@ -15,23 +15,30 @@
 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/StringSet.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/CodeGen/ParallelCG.h"
+#include "llvm/IR/AutoUpgrade.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Verifier.h"
 #include "llvm/Linker/Linker.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Object/IRObjectFile.h"
-#include "llvm/PassManager.h"
-#include "llvm/Support/FormattedStream.h"
+#include "llvm/Object/FunctionIndexObjectFile.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Host.h"
+#include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/TargetSelect.h"
-#include "llvm/Target/TargetLibraryInfo.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/Utils/GlobalStatus.h"
@@ -78,14 +85,29 @@ static std::vector<std::string> Cleanup;
 static llvm::TargetOptions TargetOpts;
 
 namespace options {
-  enum generate_bc { BC_NO, BC_ALSO, BC_ONLY };
+  enum OutputType {
+    OT_NORMAL,
+    OT_DISABLE,
+    OT_BC_ONLY,
+    OT_SAVE_TEMPS
+  };
   static bool generate_api_file = false;
-  static generate_bc generate_bc_file = BC_NO;
-  static std::string bc_path;
+  static OutputType TheOutputType = OT_NORMAL;
+  static unsigned OptLevel = 2;
+  static unsigned Parallelism = 1;
+#ifdef NDEBUG
+  static bool DisableVerify = true;
+#else
+  static bool DisableVerify = false;
+#endif
   static std::string obj_path;
   static std::string extra_library_path;
   static std::string triple;
   static std::string mcpu;
+  // When the thinlto plugin option is specified, only read the function
+  // the information from intermediate files and write a combined
+  // global index for the ThinLTO backends.
+  static bool thinlto = false;
   // Additional options to pass into the code generator.
   // Note: This array will contain all plugin options which are not claimed
   // as plugin exclusive to pass to the code generator.
@@ -93,7 +115,7 @@ namespace options {
   // use only and will not be passed.
   static std::vector<const char *> extra;
 
-  static void process_plugin_option(const char* opt_)
+  static void process_plugin_option(const char *opt_)
   {
     if (opt_ == nullptr)
       return;
@@ -110,19 +132,22 @@ namespace options {
     } else if (opt.startswith("obj-path=")) {
       obj_path = opt.substr(strlen("obj-path="));
     } else if (opt == "emit-llvm") {
-      generate_bc_file = BC_ONLY;
-    } else if (opt == "also-emit-llvm") {
-      generate_bc_file = BC_ALSO;
-    } else if (opt.startswith("also-emit-llvm=")) {
-      llvm::StringRef path = opt.substr(strlen("also-emit-llvm="));
-      generate_bc_file = BC_ALSO;
-      if (!bc_path.empty()) {
-        message(LDPL_WARNING, "Path to the output IL file specified twice. "
-                              "Discarding %s",
-                opt_);
-      } else {
-        bc_path = path;
-      }
+      TheOutputType = OT_BC_ONLY;
+    } else if (opt == "save-temps") {
+      TheOutputType = OT_SAVE_TEMPS;
+    } else if (opt == "disable-output") {
+      TheOutputType = OT_DISABLE;
+    } else if (opt == "thinlto") {
+      thinlto = true;
+    } else if (opt.size() == 2 && opt[0] == 'O') {
+      if (opt[1] < '0' || opt[1] > '3')
+        message(LDPL_FATAL, "Optimization level must be between 0 and 3");
+      OptLevel = opt[1] - '0';
+    } else if (opt.startswith("jobs=")) {
+      if (StringRef(opt_ + 5).getAsInteger(10, Parallelism))
+        message(LDPL_FATAL, "Invalid parallelism level: %s", opt_ + 5);
+    } else if (opt == "disable-verify") {
+      DisableVerify = true;
     } else {
       // Save this option to pass to the code generator.
       // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
@@ -264,6 +289,49 @@ static const GlobalObject *getBaseObject(const GlobalValue &GV) {
   return cast<GlobalObject>(&GV);
 }
 
+static bool shouldSkip(uint32_t Symflags) {
+  if (!(Symflags & object::BasicSymbolRef::SF_Global))
+    return true;
+  if (Symflags & object::BasicSymbolRef::SF_FormatSpecific)
+    return true;
+  return false;
+}
+
+static void diagnosticHandler(const DiagnosticInfo &DI) {
+  if (const auto *BDI = dyn_cast<BitcodeDiagnosticInfo>(&DI)) {
+    std::error_code EC = BDI->getError();
+    if (EC == BitcodeError::InvalidBitcodeSignature)
+      return;
+  }
+
+  std::string ErrStorage;
+  {
+    raw_string_ostream OS(ErrStorage);
+    DiagnosticPrinterRawOStream DP(OS);
+    DI.print(DP);
+  }
+  ld_plugin_level Level;
+  switch (DI.getSeverity()) {
+  case DS_Error:
+    message(LDPL_FATAL, "LLVM gold plugin has failed to create LTO module: %s",
+            ErrStorage.c_str());
+    llvm_unreachable("Fatal doesn't return.");
+  case DS_Warning:
+    Level = LDPL_WARNING;
+    break;
+  case DS_Note:
+  case DS_Remark:
+    Level = LDPL_INFO;
+    break;
+  }
+  message(Level, "LLVM gold plugin: %s",  ErrStorage.c_str());
+}
+
+static void diagnosticHandlerForContext(const DiagnosticInfo &DI,
+                                        void *Context) {
+  diagnosticHandler(DI);
+}
+
 /// Called by gold to see whether this file is one that our plugin can handle.
 /// We'll try to open it and register all the symbols with add_symbol if
 /// possible.
@@ -278,7 +346,8 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
       message(LDPL_ERROR, "Failed to get a view of %s", file->name);
       return LDPS_ERR;
     }
-    BufferRef = MemoryBufferRef(StringRef((char *)view, file->filesize), "");
+    BufferRef =
+        MemoryBufferRef(StringRef((const char *)view, file->filesize), "");
   } else {
     int64_t offset = 0;
     // Gold has found what might be IR part-way inside of a file, such as
@@ -297,10 +366,12 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
     BufferRef = Buffer->getMemBufferRef();
   }
 
+  Context.setDiagnosticHandler(diagnosticHandlerForContext);
   ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
-      object::IRObjectFile::createIRObjectFile(BufferRef, Context);
+      object::IRObjectFile::create(BufferRef, Context);
   std::error_code EC = ObjOrErr.getError();
-  if (EC == BitcodeError::InvalidBitcodeSignature)
+  if (EC == object::object_error::invalid_file_type ||
+      EC == object::object_error::bitcode_section_not_found)
     return LDPS_OK;
 
   *claimed = 1;
@@ -317,12 +388,14 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
 
   cf.handle = file->handle;
 
+  // If we are doing ThinLTO compilation, don't need to process the symbols.
+  // Later we simply build a combined index file after all files are claimed.
+  if (options::thinlto)
+    return LDPS_OK;
+
   for (auto &Sym : Obj->symbols()) {
     uint32_t Symflags = Sym.getFlags();
-    if (!(Symflags & object::BasicSymbolRef::SF_Global))
-      continue;
-
-    if (Symflags & object::BasicSymbolRef::SF_FormatSpecific)
+    if (shouldSkip(Symflags))
       continue;
 
     cf.syms.push_back(ld_plugin_symbol());
@@ -386,7 +459,7 @@ static ld_plugin_status claim_file_hook(const ld_plugin_input_file *file,
   }
 
   if (!cf.syms.empty()) {
-    if (add_symbols(cf.handle, cf.syms.size(), &cf.syms[0]) != LDPS_OK) {
+    if (add_symbols(cf.handle, cf.syms.size(), cf.syms.data()) != LDPS_OK) {
       message(LDPL_ERROR, "Unable to add symbols!");
       return LDPS_ERR;
     }
@@ -416,18 +489,8 @@ static void keepGlobalValue(GlobalValue &GV,
   assert(!GV.isDiscardableIfUnused());
 }
 
-static bool isDeclaration(const GlobalValue &V) {
-  if (V.hasAvailableExternallyLinkage())
-    return true;
-
-  if (V.isMaterializable())
-    return false;
-
-  return V.isDeclaration();
-}
-
 static void internalize(GlobalValue &GV) {
-  if (isDeclaration(GV))
+  if (GV.isDeclarationForLinker())
     return; // We get here if there is a matching asm definition.
   if (!GV.hasLocalLinkage())
     GV.setLinkage(GlobalValue::InternalLinkage);
@@ -483,35 +546,13 @@ static const char *getResolutionName(ld_plugin_symbol_resolution R) {
   case LDPR_PREVAILING_DEF_IRONLY_EXP:
     return "PREVAILING_DEF_IRONLY_EXP";
   }
-}
-
-static GlobalObject *makeInternalReplacement(GlobalObject *GO) {
-  Module *M = GO->getParent();
-  GlobalObject *Ret;
-  if (auto *F = dyn_cast<Function>(GO)) {
-    auto *NewF = Function::Create(
-        F->getFunctionType(), GlobalValue::InternalLinkage, F->getName(), M);
-    NewF->getBasicBlockList().splice(NewF->end(), F->getBasicBlockList());
-    Ret = NewF;
-    F->deleteBody();
-  } else {
-    auto *Var = cast<GlobalVariable>(GO);
-    Ret = new GlobalVariable(
-        *M, Var->getType()->getElementType(), Var->isConstant(),
-        GlobalValue::InternalLinkage, Var->getInitializer(), Var->getName(),
-        nullptr, Var->getThreadLocalMode(), Var->getType()->getAddressSpace(),
-        Var->isExternallyInitialized());
-    Var->setInitializer(nullptr);
-  }
-  Ret->copyAttributesFrom(GO);
-  Ret->setComdat(GO->getComdat());
-
-  return Ret;
+  llvm_unreachable("Unknown resolution");
 }
 
 namespace {
-class LocalValueMaterializer : public ValueMaterializer {
+class LocalValueMaterializer final : public ValueMaterializer {
   DenseSet<GlobalValue *> &Dropped;
+  DenseMap<GlobalObject *, GlobalObject *> LocalVersions;
 
 public:
   LocalValueMaterializer(DenseSet<GlobalValue *> &Dropped) : Dropped(Dropped) {}
@@ -520,13 +561,39 @@ public:
 }
 
 Value *LocalValueMaterializer::materializeValueFor(Value *V) {
-  auto *GV = dyn_cast<GlobalValue>(V);
-  if (!GV)
+  auto *GO = dyn_cast<GlobalObject>(V);
+  if (!GO)
     return nullptr;
-  if (!Dropped.count(GV))
+
+  auto I = LocalVersions.find(GO);
+  if (I != LocalVersions.end())
+    return I->second;
+
+  if (!Dropped.count(GO))
     return nullptr;
-  assert(!isa<GlobalAlias>(GV) && "Found alias point to weak alias.");
-  return makeInternalReplacement(cast<GlobalObject>(GV));
+
+  Module &M = *GO->getParent();
+  GlobalValue::LinkageTypes L = GO->getLinkage();
+  GlobalObject *Declaration;
+  if (auto *F = dyn_cast<Function>(GO)) {
+    Declaration = Function::Create(F->getFunctionType(), L, "", &M);
+  } else {
+    auto *Var = cast<GlobalVariable>(GO);
+    Declaration = new GlobalVariable(M, Var->getType()->getElementType(),
+                                     Var->isConstant(), L,
+                                     /*Initializer*/ nullptr);
+  }
+  Declaration->takeName(GO);
+  Declaration->copyAttributesFrom(GO);
+
+  GO->setLinkage(GlobalValue::InternalLinkage);
+  GO->setName(Declaration->getName());
+  Dropped.erase(GO);
+  GO->replaceAllUsesWith(Declaration);
+
+  LocalVersions[Declaration] = GO;
+
+  return GO;
 }
 
 static Constant *mapConstantToLocalCopy(Constant *C, ValueToValueMapTy &VM,
@@ -534,12 +601,15 @@ static Constant *mapConstantToLocalCopy(Constant *C, ValueToValueMapTy &VM,
   return MapValue(C, VM, RF_IgnoreMissingEntries, nullptr, Materializer);
 }
 
-static std::unique_ptr<Module>
-getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
-                 StringSet<> &Internalize, StringSet<> &Maybe) {
-  ld_plugin_input_file File;
-  if (get_input_file(F.handle, &File) != LDPS_OK)
-    message(LDPL_FATAL, "Failed to get file information");
+static void freeSymName(ld_plugin_symbol &Sym) {
+  free(Sym.name);
+  free(Sym.comdat_key);
+  Sym.name = nullptr;
+  Sym.comdat_key = nullptr;
+}
+
+static std::unique_ptr<FunctionInfoIndex>
+getFunctionIndexForFile(claimed_file &F, ld_plugin_input_file &Info) {
 
   if (get_symbols(F.handle, F.syms.size(), &F.syms[0]) != LDPS_OK)
     message(LDPL_FATAL, "Failed to get symbol information");
@@ -548,35 +618,72 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
   if (get_view(F.handle, &View) != LDPS_OK)
     message(LDPL_FATAL, "Failed to get a view of file");
 
-  std::unique_ptr<MemoryBuffer> Buffer = MemoryBuffer::getMemBuffer(
-      StringRef((char *)View, File.filesize), "", false);
+  MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
+                            Info.name);
+  ErrorOr<std::unique_ptr<object::FunctionIndexObjectFile>> ObjOrErr =
+      object::FunctionIndexObjectFile::create(BufferRef, diagnosticHandler);
 
-  if (release_input_file(F.handle) != LDPS_OK)
-    message(LDPL_FATAL, "Failed to release file information");
+  if (std::error_code EC = ObjOrErr.getError())
+    message(LDPL_FATAL, "Could not read function index bitcode from file : %s",
+            EC.message().c_str());
 
-  ErrorOr<Module *> MOrErr = getLazyBitcodeModule(std::move(Buffer), Context);
+  object::FunctionIndexObjectFile &Obj = **ObjOrErr;
 
-  if (std::error_code EC = MOrErr.getError())
+  return Obj.takeIndex();
+}
+
+static std::unique_ptr<Module>
+getModuleForFile(LLVMContext &Context, claimed_file &F,
+                 ld_plugin_input_file &Info, raw_fd_ostream *ApiFile,
+                 StringSet<> &Internalize, StringSet<> &Maybe) {
+
+  if (get_symbols(F.handle, F.syms.size(), F.syms.data()) != LDPS_OK)
+    message(LDPL_FATAL, "Failed to get symbol information");
+
+  const void *View;
+  if (get_view(F.handle, &View) != LDPS_OK)
+    message(LDPL_FATAL, "Failed to get a view of file");
+
+  MemoryBufferRef BufferRef(StringRef((const char *)View, Info.filesize),
+                            Info.name);
+  ErrorOr<std::unique_ptr<object::IRObjectFile>> ObjOrErr =
+      object::IRObjectFile::create(BufferRef, Context);
+
+  if (std::error_code EC = ObjOrErr.getError())
     message(LDPL_FATAL, "Could not read bitcode from file : %s",
             EC.message().c_str());
 
-  std::unique_ptr<Module> M(MOrErr.get());
+  object::IRObjectFile &Obj = **ObjOrErr;
+
+  Module &M = Obj.getModule();
+
+  M.materializeMetadata();
+  UpgradeDebugInfo(M);
 
   SmallPtrSet<GlobalValue *, 8> Used;
-  collectUsedGlobalVariables(*M, Used, /*CompilerUsed*/ false);
+  collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
 
   DenseSet<GlobalValue *> Drop;
   std::vector<GlobalAlias *> KeptAliases;
-  for (ld_plugin_symbol &Sym : F.syms) {
+
+  unsigned SymNum = 0;
+  for (auto &ObjSym : Obj.symbols()) {
+    if (shouldSkip(ObjSym.getFlags()))
+      continue;
+    ld_plugin_symbol &Sym = F.syms[SymNum];
+    ++SymNum;
+
     ld_plugin_symbol_resolution Resolution =
         (ld_plugin_symbol_resolution)Sym.resolution;
 
     if (options::generate_api_file)
       *ApiFile << Sym.name << ' ' << getResolutionName(Resolution) << '\n';
 
-    GlobalValue *GV = M->getNamedValue(Sym.name);
-    if (!GV)
+    GlobalValue *GV = Obj.getSymbolGV(ObjSym.getRawDataRefImpl());
+    if (!GV) {
+      freeSymName(Sym);
       continue; // Asm symbol.
+    }
 
     if (Resolution != LDPR_PREVAILING_DEF_IRONLY && GV->hasCommonLinkage()) {
       // Common linkage is special. There is no single symbol that wins the
@@ -584,6 +691,7 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
       // The IR linker does that for us if we just pass it every common GV.
       // We still have to keep track of LDPR_PREVAILING_DEF_IRONLY so we
       // internalize once the IR linker has done its job.
+      freeSymName(Sym);
       continue;
     }
 
@@ -594,8 +702,14 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
     case LDPR_RESOLVED_IR:
     case LDPR_RESOLVED_EXEC:
     case LDPR_RESOLVED_DYN:
+      assert(GV->isDeclarationForLinker());
+      break;
+
     case LDPR_UNDEF:
-      assert(isDeclaration(*GV));
+      if (!GV->isDeclarationForLinker()) {
+        assert(GV->hasComdat());
+        Drop.insert(GV);
+      }
       break;
 
     case LDPR_PREVAILING_DEF_IRONLY: {
@@ -604,7 +718,7 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
         // Since we use the regular lib/Linker, we cannot just internalize GV
         // now or it will not be copied to the merged module. Instead we force
         // it to be copied and then internalize it.
-        Internalize.insert(Sym.name);
+        Internalize.insert(GV->getName());
       }
       break;
     }
@@ -613,8 +727,14 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
       keepGlobalValue(*GV, KeptAliases);
       break;
 
-    case LDPR_PREEMPTED_REG:
     case LDPR_PREEMPTED_IR:
+      // Gold might have selected a linkonce_odr and preempted a weak_odr.
+      // In that case we have to make sure we don't end up internalizing it.
+      if (!GV->isDiscardableIfUnused())
+        Maybe.erase(GV->getName());
+
+      // fall-through
+    case LDPR_PREEMPTED_REG:
       Drop.insert(GV);
       break;
 
@@ -624,24 +744,15 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
       // and in that module the address might be significant, but that
       // copy will be LDPR_PREEMPTED_IR.
       if (GV->hasLinkOnceODRLinkage())
-        Maybe.insert(Sym.name);
+        Maybe.insert(GV->getName());
       keepGlobalValue(*GV, KeptAliases);
       break;
     }
     }
 
-    free(Sym.name);
-    free(Sym.comdat_key);
-    Sym.name = nullptr;
-    Sym.comdat_key = nullptr;
+    freeSymName(Sym);
   }
 
-  if (!Drop.empty())
-    // This is horrible. Given how lazy loading is implemented, dropping
-    // the body while there is a materializer present doesn't work, the
-    // linker will just read the body back.
-    M->materializeAllPermanently();
-
   ValueToValueMapTy VM;
   LocalValueMaterializer Materializer(Drop);
   for (GlobalAlias *GA : KeptAliases) {
@@ -649,29 +760,45 @@ getModuleForFile(LLVMContext &Context, claimed_file &F, raw_fd_ostream *ApiFile,
     // expression is being dropped. If that is the case, that GV must be copied.
     Constant *Aliasee = GA->getAliasee();
     Constant *Replacement = mapConstantToLocalCopy(Aliasee, VM, &Materializer);
-    if (Aliasee != Replacement)
-      GA->setAliasee(Replacement);
+    GA->setAliasee(Replacement);
   }
 
   for (auto *GV : Drop)
     drop(*GV);
 
-  return M;
+  return Obj.takeModule();
 }
 
 static void runLTOPasses(Module &M, TargetMachine &TM) {
-  PassManager passes;
+  M.setDataLayout(TM.createDataLayout());
+
+  legacy::PassManager passes;
+  passes.add(createTargetTransformInfoWrapperPass(TM.getTargetIRAnalysis()));
+
   PassManagerBuilder PMB;
-  PMB.LibraryInfo = new TargetLibraryInfo(Triple(TM.getTargetTriple()));
+  PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM.getTargetTriple()));
   PMB.Inliner = createFunctionInliningPass();
+  // Unconditionally verify input since it is not verified before this
+  // point and has unknown origin.
   PMB.VerifyInput = true;
-  PMB.VerifyOutput = true;
-  PMB.populateLTOPassManager(passes, &TM);
+  PMB.VerifyOutput = !options::DisableVerify;
+  PMB.LoopVectorize = true;
+  PMB.SLPVectorize = true;
+  PMB.OptLevel = options::OptLevel;
+  PMB.populateLTOPassManager(passes);
   passes.run(M);
 }
 
-static void codegen(Module &M) {
-  const std::string &TripleStr = M.getTargetTriple();
+static void saveBCFile(StringRef Path, Module &M) {
+  std::error_code EC;
+  raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::F_None);
+  if (EC)
+    message(LDPL_FATAL, "Failed to write the output file.");
+  WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true);
+}
+
+static void codegen(std::unique_ptr<Module> M) {
+  const std::string &TripleStr = M->getTargetTriple();
   Triple TheTriple(TripleStr);
 
   std::string ErrMsg;
@@ -688,48 +815,77 @@ static void codegen(Module &M) {
     Features.AddFeature(A);
 
   TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
+  CodeGenOpt::Level CGOptLevel;
+  switch (options::OptLevel) {
+  case 0:
+    CGOptLevel = CodeGenOpt::None;
+    break;
+  case 1:
+    CGOptLevel = CodeGenOpt::Less;
+    break;
+  case 2:
+    CGOptLevel = CodeGenOpt::Default;
+    break;
+  case 3:
+    CGOptLevel = CodeGenOpt::Aggressive;
+    break;
+  }
   std::unique_ptr<TargetMachine> TM(TheTarget->createTargetMachine(
       TripleStr, options::mcpu, Features.getString(), Options, RelocationModel,
-      CodeModel::Default, CodeGenOpt::Aggressive));
+      CodeModel::Default, CGOptLevel));
 
-  runLTOPasses(M, *TM);
+  runLTOPasses(*M, *TM);
 
-  PassManager CodeGenPasses;
-  CodeGenPasses.add(new DataLayoutPass());
+  if (options::TheOutputType == options::OT_SAVE_TEMPS)
+    saveBCFile(output_name + ".opt.bc", *M);
 
   SmallString<128> Filename;
-  int FD;
-  if (options::obj_path.empty()) {
-    std::error_code EC =
-        sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filename);
-    if (EC)
-      message(LDPL_FATAL, "Could not create temorary file: %s",
-              EC.message().c_str());
-  } else {
+  if (!options::obj_path.empty())
     Filename = options::obj_path;
-    std::error_code EC =
-        sys::fs::openFileForWrite(Filename.c_str(), FD, sys::fs::F_None);
-    if (EC)
-      message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
-  }
+  else if (options::TheOutputType == options::OT_SAVE_TEMPS)
+    Filename = output_name + ".o";
 
+  std::vector<SmallString<128>> Filenames(options::Parallelism);
+  bool TempOutFile = Filename.empty();
   {
-    raw_fd_ostream OS(FD, true);
-    formatted_raw_ostream FOS(OS);
+    // Open a file descriptor for each backend thread. This is done in a block
+    // so that the output file descriptors are closed before gold opens them.
+    std::list<llvm::raw_fd_ostream> OSs;
+    std::vector<llvm::raw_pwrite_stream *> OSPtrs(options::Parallelism);
+    for (unsigned I = 0; I != options::Parallelism; ++I) {
+      int FD;
+      if (TempOutFile) {
+        std::error_code EC =
+            sys::fs::createTemporaryFile("lto-llvm", "o", FD, Filenames[I]);
+        if (EC)
+          message(LDPL_FATAL, "Could not create temporary file: %s",
+                  EC.message().c_str());
+      } else {
+        Filenames[I] = Filename;
+        if (options::Parallelism != 1)
+          Filenames[I] += utostr(I);
+        std::error_code EC =
+            sys::fs::openFileForWrite(Filenames[I], FD, sys::fs::F_None);
+        if (EC)
+          message(LDPL_FATAL, "Could not open file: %s", EC.message().c_str());
+      }
+      OSs.emplace_back(FD, true);
+      OSPtrs[I] = &OSs.back();
+    }
 
-    if (TM->addPassesToEmitFile(CodeGenPasses, FOS,
-                                TargetMachine::CGFT_ObjectFile))
-      message(LDPL_FATAL, "Failed to setup codegen");
-    CodeGenPasses.run(M);
+    // Run backend threads.
+    splitCodeGen(std::move(M), OSPtrs, options::mcpu, Features.getString(),
+                 Options, RelocationModel, CodeModel::Default, CGOptLevel);
   }
 
-  if (add_input_file(Filename.c_str()) != LDPS_OK)
-    message(LDPL_FATAL,
-            "Unable to add .o file to the link. File left behind in: %s",
-            Filename.c_str());
-
-  if (options::obj_path.empty())
-    Cleanup.push_back(Filename.c_str());
+  for (auto &Filename : Filenames) {
+    if (add_input_file(Filename.c_str()) != LDPS_OK)
+      message(LDPL_FATAL,
+              "Unable to add .o file to the link. File left behind in: %s",
+              Filename.c_str());
+    if (TempOutFile)
+      Cleanup.push_back(Filename.c_str());
+  }
 }
 
 /// gold informs us that all symbols have been read. At this point, we use
@@ -740,6 +896,37 @@ static ld_plugin_status allSymbolsReadHook(raw_fd_ostream *ApiFile) {
     return LDPS_OK;
 
   LLVMContext Context;
+  Context.setDiagnosticHandler(diagnosticHandlerForContext, nullptr, true);
+
+  // If we are doing ThinLTO compilation, simply build the combined
+  // function index/summary and emit it. We don't need to parse the modules
+  // and link them in this case.
+  if (options::thinlto) {
+    FunctionInfoIndex CombinedIndex;
+    uint64_t NextModuleId = 0;
+    for (claimed_file &F : Modules) {
+      ld_plugin_input_file File;
+      if (get_input_file(F.handle, &File) != LDPS_OK)
+        message(LDPL_FATAL, "Failed to get file information");
+
+      std::unique_ptr<FunctionInfoIndex> Index =
+          getFunctionIndexForFile(F, File);
+      CombinedIndex.mergeFrom(std::move(Index), ++NextModuleId);
+    }
+
+    std::error_code EC;
+    raw_fd_ostream OS(output_name + ".thinlto.bc", EC,
+                      sys::fs::OpenFlags::F_None);
+    if (EC)
+      message(LDPL_FATAL, "Unable to open %s.thinlto.bc for writing: %s",
+              output_name.data(), EC.message().c_str());
+    WriteFunctionSummaryToFile(CombinedIndex, OS);
+    OS.close();
+
+    cleanup_hook();
+    exit(0);
+  }
+
   std::unique_ptr<Module> Combined(new Module("ld-temp.o", Context));
   Linker L(Combined.get());
 
@@ -748,17 +935,21 @@ static ld_plugin_status allSymbolsReadHook(raw_fd_ostream *ApiFile) {
   StringSet<> Internalize;
   StringSet<> Maybe;
   for (claimed_file &F : Modules) {
+    ld_plugin_input_file File;
+    if (get_input_file(F.handle, &File) != LDPS_OK)
+      message(LDPL_FATAL, "Failed to get file information");
     std::unique_ptr<Module> M =
-        getModuleForFile(Context, F, ApiFile, Internalize, Maybe);
+        getModuleForFile(Context, F, File, ApiFile, Internalize, Maybe);
     if (!options::triple.empty())
       M->setTargetTriple(options::triple.c_str());
     else if (M->getTargetTriple().empty()) {
       M->setTargetTriple(DefaultTriple);
     }
 
-    std::string ErrMsg;
-    if (L.linkInModule(M.get(), &ErrMsg))
-      message(LDPL_FATAL, "Failed to link module: %s", ErrMsg.c_str());
+    if (L.linkInModule(M.get()))
+      message(LDPL_FATAL, "Failed to link module");
+    if (release_input_file(F.handle) != LDPS_OK)
+      message(LDPL_FATAL, "Failed to release file information");
   }
 
   for (const auto &Name : Internalize) {
@@ -776,26 +967,21 @@ static ld_plugin_status allSymbolsReadHook(raw_fd_ostream *ApiFile) {
       internalize(*GV);
   }
 
-  if (options::generate_bc_file != options::BC_NO) {
+  if (options::TheOutputType == options::OT_DISABLE)
+    return LDPS_OK;
+
+  if (options::TheOutputType != options::OT_NORMAL) {
     std::string path;
-    if (options::generate_bc_file == options::BC_ONLY)
+    if (options::TheOutputType == options::OT_BC_ONLY)
       path = output_name;
-    else if (!options::bc_path.empty())
-      path = options::bc_path;
     else
       path = output_name + ".bc";
-    {
-      std::error_code EC;
-      raw_fd_ostream OS(path, EC, sys::fs::OpenFlags::F_None);
-      if (EC)
-        message(LDPL_FATAL, "Failed to write the output file.");
-      WriteBitcodeToFile(L.getModule(), OS);
-    }
-    if (options::generate_bc_file == options::BC_ONLY)
+    saveBCFile(path, *L.getModule());
+    if (options::TheOutputType == options::OT_BC_ONLY)
       return LDPS_OK;
   }
 
-  codegen(*L.getModule());
+  codegen(std::move(Combined));
 
   if (!options::extra_library_path.empty() &&
       set_extra_library_path(options::extra_library_path.c_str()) != LDPS_OK)
@@ -817,8 +1003,16 @@ static ld_plugin_status all_symbols_read_hook(void) {
     Ret = allSymbolsReadHook(&ApiFile);
   }
 
-  if (options::generate_bc_file == options::BC_ONLY)
+  llvm_shutdown();
+
+  if (options::TheOutputType == options::OT_BC_ONLY ||
+      options::TheOutputType == options::OT_DISABLE) {
+    if (options::TheOutputType == options::OT_DISABLE)
+      // Remove the output file here since ld.bfd creates the output file
+      // early.
+      sys::fs::remove(output_name);
     exit(0);
+  }
 
   return Ret;
 }