Revert "[LTO] Support LLVM level link time optimization on Darwin, Linux and Windows"

include/swift/AST/IRGenOptions.h

@@ -65,12 +65,6 @@ enum class IRGenDebugInfoFormat : unsigned {
   CodeView
 };
 
-enum class IRGenLLVMLTOKind : unsigned {
-  None,
-  Thin,
-  Full
-};
-
 enum class IRGenEmbedMode : unsigned {
   None,
   EmbedMarker,
@@ -223,8 +217,6 @@ public:
   /// Whether we should embed the bitcode file.
   IRGenEmbedMode EmbedMode : 2;
 
-  IRGenLLVMLTOKind LLVMLTOKind: 2;
-
   /// Add names to LLVM values.
   unsigned HasValueNamesSetting : 1;
   unsigned ValueNames : 1;
@@ -326,7 +318,6 @@ public:
         DisableSwiftSpecificLLVMOptzns(false), DisableLLVMSLPVectorizer(false),
         Playground(false), EmitStackPromotionChecks(false),
         FunctionSections(false), PrintInlineTree(false), EmbedMode(IRGenEmbedMode::None),
-        LLVMLTOKind(IRGenLLVMLTOKind::None),
         HasValueNamesSetting(false), ValueNames(false),
         EnableReflectionMetadata(true), EnableReflectionNames(true),
         EnableAnonymousContextMangledNames(false), ForcePublicLinkage(false),

include/swift/Driver/Action.h

@@ -328,19 +328,16 @@ public:
 class DynamicLinkJobAction : public JobAction {
   virtual void anchor();
   LinkKind Kind;
-  bool LTO;
 
 public:
-  DynamicLinkJobAction(ArrayRef<const Action *> Inputs, LinkKind K, bool LTO)
+  DynamicLinkJobAction(ArrayRef<const Action *> Inputs, LinkKind K)
       : JobAction(Action::Kind::DynamicLinkJob, Inputs, file_types::TY_Image),
-        Kind(K), LTO(LTO) {
+        Kind(K) {
     assert(Kind != LinkKind::None && Kind != LinkKind::StaticLibrary);
   }
 
   LinkKind getKind() const { return Kind; }
 
-  bool PerformLTO() const { return LTO; }
-
   static bool classof(const Action *A) {
     return A->getKind() == Action::Kind::DynamicLinkJob;
   }

include/swift/Driver/Driver.h

@@ -101,14 +101,6 @@ public:
   /// The output type which should be used for compile actions.
   file_types::ID CompilerOutputType = file_types::ID::TY_INVALID;
 
-  enum class LTOKind {
-    None,
-    LLVMThin,
-    LLVMFull,
-  };
-
-  LTOKind LTOVariant = LTOKind::None;
-
   /// Describes if and how the output of compile actions should be
   /// linked together.
   LinkKind LinkAction = LinkKind::None;

include/swift/Option/Options.td

@@ -515,10 +515,6 @@ def disable_bridging_pch : Flag<["-"], "disable-bridging-pch">,
   Flags<[HelpHidden]>,
   HelpText<"Disable automatic generation of bridging PCH files">;
 
-def lto : Joined<["-"], "lto=">,
-  Flags<[FrontendOption, NoInteractiveOption]>,
-  HelpText<"Specify the LTO type to either 'llvm' or 'llvm-full'">;
-
 // Experimental feature options
 
 // Note: this flag will be removed when JVP/differential generation in the

lib/Driver/DarwinToolChains.cpp

@@ -238,15 +238,12 @@ toolchains::Darwin::addLinkerInputArgs(InvocationInfo &II,
     Arguments.push_back("-filelist");
     Arguments.push_back(context.getTemporaryFilePath("inputs", "LinkFileList"));
     II.FilelistInfos.push_back(
-        {Arguments.back(), context.OI.CompilerOutputType,
+        {Arguments.back(), file_types::TY_Object,
          FilelistInfo::WhichFiles::InputJobsAndSourceInputActions});
   } else {
     addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
                            file_types::TY_Object);
-    addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                           file_types::TY_LLVM_BC);
     addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-    addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
   }
 
 
@@ -309,20 +306,6 @@ toolchains::Darwin::addArgsToLinkARCLite(ArgStringList &Arguments,
   }
 }
 
-void
-toolchains::Darwin::addLTOLibArgs(ArgStringList &Arguments,
-                                  const JobContext &context) const {
-  llvm::SmallString<128> LTOLibPath;
-  if (findXcodeClangPath(LTOLibPath)) {
-    llvm::sys::path::remove_filename(LTOLibPath); // 'clang'
-    llvm::sys::path::remove_filename(LTOLibPath); // 'bin'
-    llvm::sys::path::append(LTOLibPath, "lib", "libLTO.dylib");
-
-    Arguments.push_back("-lto_library");
-    Arguments.push_back(context.Args.MakeArgString(LTOLibPath));
-  }
-}
-
 void
 toolchains::Darwin::addSanitizerArgs(ArgStringList &Arguments,
                                      const DynamicLinkJobAction &job,
@@ -740,10 +723,6 @@ toolchains::Darwin::constructInvocation(const DynamicLinkJobAction &job,
 
   addArgsToLinkARCLite(Arguments, context);
 
-  if (job.PerformLTO()) {
-    addLTOLibArgs(Arguments, context);
-  }
-
   for (const Arg *arg :
        context.Args.filtered(options::OPT_F, options::OPT_Fsystem)) {
     Arguments.push_back("-F");
@@ -811,17 +790,14 @@ toolchains::Darwin::constructInvocation(const StaticLinkJobAction &job,
   if (context.shouldUseInputFileList()) {
     Arguments.push_back("-filelist");
     Arguments.push_back(context.getTemporaryFilePath("inputs", "LinkFileList"));
-    II.FilelistInfos.push_back({Arguments.back(), context.OI.CompilerOutputType,
+    II.FilelistInfos.push_back({Arguments.back(), file_types::TY_Object,
                                 FilelistInfo::WhichFiles::InputJobs});
   } else {
     addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
                            file_types::TY_Object);
-    addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                           file_types::TY_LLVM_BC);
   }
 
   addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-  addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
 
   Arguments.push_back("-o");
 

lib/Driver/Driver.cpp

@@ -1427,15 +1427,12 @@ static bool isSDKTooOld(StringRef sdkPath, const llvm::Triple &target) {
 void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
                              const bool BatchMode, const InputFileList &Inputs,
                              OutputInfo &OI) const {
-  auto LinkerInputType = Args.hasArg(options::OPT_lto)
-                            ? file_types::TY_LLVM_BC
-                            : file_types::TY_Object;
   // By default, the driver does not link its output; this will be updated
   // appropriately below if linking is required.
 
   OI.CompilerOutputType = driverKind == DriverKind::Interactive
                               ? file_types::TY_Nothing
-                              : LinkerInputType;
+                              : file_types::TY_Object;
 
   if (const Arg *A = Args.getLastArg(options::OPT_num_threads)) {
     if (BatchMode) {
@@ -1465,14 +1462,14 @@ void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
                        diag::error_static_emit_executable_disallowed);
                        
       OI.LinkAction = LinkKind::Executable;
-      OI.CompilerOutputType = LinkerInputType;
+      OI.CompilerOutputType = file_types::TY_Object;
       break;
 
     case options::OPT_emit_library:
       OI.LinkAction = Args.hasArg(options::OPT_static) ?
                       LinkKind::StaticLibrary :
                       LinkKind::DynamicLibrary;
-      OI.CompilerOutputType = LinkerInputType;
+      OI.CompilerOutputType = file_types::TY_Object;
       break;
 
     case options::OPT_static:
@@ -1782,18 +1779,6 @@ void Driver::buildOutputInfo(const ToolChain &TC, const DerivedArgList &Args,
 
   }
 
-  if (const Arg *A = Args.getLastArg(options::OPT_lto)) {
-    auto LTOVariant = llvm::StringSwitch<Optional<OutputInfo::LTOKind>>(A->getValue())
-      .Case("llvm", OutputInfo::LTOKind::LLVMThin)
-      .Case("llvm-full", OutputInfo::LTOKind::LLVMFull)
-      .Default(llvm::None);
-    if (LTOVariant)
-      OI.LTOVariant = LTOVariant.getValue();
-    else
-      Diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
-                     A->getAsString(Args), A->getValue());
-  }
-
   if (TC.getTriple().isOSWindows()) {
     if (const Arg *A = Args.getLastArg(options::OPT_libc)) {
       OI.RuntimeVariant =
@@ -2128,17 +2113,15 @@ void Driver::buildActions(SmallVectorImpl<const Action *> &TopLevelActions,
     MergeModuleAction = C.createAction<MergeModuleJobAction>(AllModuleInputs);
   }
 
-  auto PerformLTO = Args.hasArg(options::OPT_lto);
   if (OI.shouldLink() && !AllLinkerInputs.empty()) {
     JobAction *LinkAction = nullptr;
 
     if (OI.LinkAction == LinkKind::StaticLibrary) {
       LinkAction = C.createAction<StaticLinkJobAction>(AllLinkerInputs,
-                                                       OI.LinkAction);
+                                                    OI.LinkAction);
     } else {
       LinkAction = C.createAction<DynamicLinkJobAction>(AllLinkerInputs,
-                                                        OI.LinkAction,
+                                                 OI.LinkAction);
-                                                        PerformLTO);
     }
 
     // On ELF platforms there's no built in autolinking mechanism, so we
@@ -2147,7 +2130,7 @@ void Driver::buildActions(SmallVectorImpl<const Action *> &TopLevelActions,
     const auto &Triple = TC.getTriple();
     SmallVector<const Action *, 2> AutolinkExtractInputs;
     for (const Action *A : AllLinkerInputs)
-      if (A->getType() == OI.CompilerOutputType) {
+      if (A->getType() == file_types::TY_Object) {
         // Shared objects on ELF platforms don't have a swift1_autolink_entries
         // section in them because the section in the .o files is marked as
         // SHF_EXCLUDE.
@@ -2163,7 +2146,7 @@ void Driver::buildActions(SmallVectorImpl<const Action *> &TopLevelActions,
         (Triple.getObjectFormat() == llvm::Triple::ELF && !Triple.isPS4()) ||
         Triple.getObjectFormat() == llvm::Triple::Wasm ||
         Triple.isOSCygMing();
-    if (!AutolinkExtractInputs.empty() && AutolinkExtractRequired && !PerformLTO) {
+    if (!AutolinkExtractInputs.empty() && AutolinkExtractRequired) {
       auto *AutolinkExtractAction =
           C.createAction<AutolinkExtractJobAction>(AutolinkExtractInputs);
       // Takes the same inputs as the linker...

lib/Driver/ToolChains.cpp

@@ -518,11 +518,6 @@ ToolChain::constructInvocation(const CompileJobAction &job,
     Arguments.push_back("-track-system-dependencies");
   }
 
-  if (auto arg = context.Args.getLastArg(options::OPT_lto)) {
-    Arguments.push_back(context.Args.MakeArgString(
-        Twine("-lto=") + arg->getValue()));
-  }
-
   context.Args.AddLastArg(
       Arguments,
       options::

lib/Driver/ToolChains.h

@@ -48,9 +48,6 @@ protected:
   void addDeploymentTargetArgs(llvm::opt::ArgStringList &Arguments,
                                const JobContext &context) const;
 
-  void addLTOLibArgs(llvm::opt::ArgStringList &Arguments,
-                     const JobContext &context) const;
-
   void addCommonFrontendArgs(
       const OutputInfo &OI, const CommandOutput &output,
       const llvm::opt::ArgList &inputArgs,

lib/Driver/UnixToolChains.cpp

@@ -72,10 +72,7 @@ ToolChain::InvocationInfo toolchains::GenericUnix::constructInvocation(
 
   addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
                          file_types::TY_Object);
-  addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                         file_types::TY_LLVM_BC);
   addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-  addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
 
   Arguments.push_back("-o");
   Arguments.push_back(
@@ -170,9 +167,6 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
   std::string Linker;
   if (const Arg *A = context.Args.getLastArg(options::OPT_use_ld)) {
     Linker = A->getValue();
-  } else if (context.OI.LTOVariant != OutputInfo::LTOKind::None) {
-    // Force to use lld for LTO
-    Linker = "lld";
   } else {
     Linker = getDefaultLinker();
   }
@@ -224,16 +218,6 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
     Arguments.push_back("-pie");
   }
 
-  switch (context.OI.LTOVariant) {
-  case OutputInfo::LTOKind::LLVMThin:
-    Arguments.push_back("-flto=thin");
-    break;
-  case OutputInfo::LTOKind::LLVMFull:
-    Arguments.push_back("-flto=full");
-    break;
-  case OutputInfo::LTOKind::None: break;
-  }
-
   bool staticExecutable = false;
   bool staticStdlib = false;
 
@@ -269,11 +253,7 @@ toolchains::GenericUnix::constructInvocation(const DynamicLinkJobAction &job,
 
   addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
                          file_types::TY_Object);
-  addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                         file_types::TY_LLVM_BC);
   addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-  addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
-
 
   for (const Arg *arg :
        context.Args.filtered(options::OPT_F, options::OPT_Fsystem)) {
@@ -388,7 +368,7 @@ toolchains::GenericUnix::constructInvocation(const StaticLinkJobAction &job,
   ArgStringList Arguments;
 
   // Configure the toolchain.
-  const char *AR = "llvm-ar";
+  const char *AR = "ar";
   Arguments.push_back("crs");
 
   Arguments.push_back(
@@ -396,11 +376,7 @@ toolchains::GenericUnix::constructInvocation(const StaticLinkJobAction &job,
 
   addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
                          file_types::TY_Object);
-  addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                         file_types::TY_LLVM_BC);
   addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-  addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
-
 
   InvocationInfo II{AR, Arguments};
 

lib/Driver/WindowsToolChains.cpp

@@ -143,11 +143,7 @@ toolchains::Windows::constructInvocation(const DynamicLinkJobAction &job,
 
   addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
                          file_types::TY_Object);
-  addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                         file_types::TY_LLVM_BC);
   addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-  addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
-
 
   for (const Arg *arg :
        context.Args.filtered(options::OPT_F, options::OPT_Fsystem)) {
@@ -190,21 +186,6 @@ toolchains::Windows::constructInvocation(const DynamicLinkJobAction &job,
   context.Args.AddAllArgs(Arguments, options::OPT_linker_option_Group);
   context.Args.AddAllArgValues(Arguments, options::OPT_Xclang_linker);
 
-  switch (context.OI.LTOVariant) {
-  case OutputInfo::LTOKind::LLVMThin:
-  case OutputInfo::LTOKind::LLVMFull: {
-    if (Linker.empty())
-      Arguments.push_back("-fuse-ld=lld");
-    if (context.OI.LTOVariant == OutputInfo::LTOKind::LLVMThin) {
-      Arguments.push_back("-flto=thin");
-    } else {
-      Arguments.push_back("-flto=full");
-    }
-    break;
-  }
-  case OutputInfo::LTOKind::None: break;
-  }
-
   // Run clang++ in verbose mode if "-v" is set
   if (context.Args.hasArg(options::OPT_v)) {
     Arguments.push_back("-v");
@@ -229,46 +210,22 @@ toolchains::Windows::constructInvocation(const StaticLinkJobAction &job,
 
   ArgStringList Arguments;
 
-  switch (context.OI.LTOVariant) {
+  const char *Linker = "link";
-  case OutputInfo::LTOKind::LLVMThin:
+  if (const Arg *A = context.Args.getLastArg(options::OPT_use_ld))
-  case OutputInfo::LTOKind::LLVMFull: {
+    Linker = context.Args.MakeArgString(A->getValue());
-    const char *AR = "llvm-ar";
-    Arguments.push_back("crs");
 
-    Arguments.push_back(
+  Arguments.push_back("/lib");
-        context.Args.MakeArgString(context.Output.getPrimaryOutputFilename()));
+  Arguments.push_back("-nologo");
 
-    addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
+  addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                           file_types::TY_Object);
+                         file_types::TY_Object);
-    addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
+  addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-                           file_types::TY_LLVM_BC);
-    addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-    addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
 
-    InvocationInfo II{AR, Arguments};
+  StringRef OutputFile = context.Output.getPrimaryOutputFilename();
+  Arguments.push_back(context.Args.MakeArgString(Twine("/OUT:") + OutputFile));
 
-    return II;
+  InvocationInfo II{Linker, Arguments};
-  }
+  II.allowsResponseFiles = true;
-  case OutputInfo::LTOKind::None:
-    const char *Linker = "link";
-    if (const Arg *A = context.Args.getLastArg(options::OPT_use_ld))
-      Linker = context.Args.MakeArgString(A->getValue());
 
-    Arguments.push_back("/lib");
+  return II;
-    Arguments.push_back("-nologo");
-
-    addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                           file_types::TY_Object);
-    addPrimaryInputsOfType(Arguments, context.Inputs, context.Args,
-                           file_types::TY_LLVM_BC);
-    addInputsOfType(Arguments, context.InputActions, file_types::TY_Object);
-    addInputsOfType(Arguments, context.InputActions, file_types::TY_LLVM_BC);
-
-    StringRef OutputFile = context.Output.getPrimaryOutputFilename();
-    Arguments.push_back(context.Args.MakeArgString(Twine("/OUT:") + OutputFile));
-
-    InvocationInfo II{Linker, Arguments};
-    II.allowsResponseFiles = true;
-    return II;
-  }
 }

lib/Frontend/CompilerInvocation.cpp

@@ -1428,17 +1428,6 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
     }
   }
 
-  if (const Arg *A = Args.getLastArg(options::OPT_lto)) {
-    auto LLVMLTOKind = llvm::StringSwitch<Optional<IRGenLLVMLTOKind>>(A->getValue())
-      .Case("llvm", IRGenLLVMLTOKind::Thin)
-      .Case("llvm-full", IRGenLLVMLTOKind::Full)
-      .Default(llvm::None);
-    if (LLVMLTOKind)
-      Opts.LLVMLTOKind = LLVMLTOKind.getValue();
-    else
-      Diags.diagnose(SourceLoc(), diag::error_invalid_arg_value,
-                     A->getAsString(Args), A->getValue());
-  }
 
   if (const Arg *A = Args.getLastArg(options::OPT_sanitize_coverage_EQ)) {
     Opts.SanitizeCoverage =

lib/IRGen/IRGen.cpp

@@ -548,14 +548,9 @@ bool swift::performLLVM(const IRGenOptions &Opts,
   case IRGenOutputKind::LLVMAssembly:
     EmitPasses.add(createPrintModulePass(*RawOS));
     break;
-  case IRGenOutputKind::LLVMBitcode: {
+  case IRGenOutputKind::LLVMBitcode:
-    if (Opts.LLVMLTOKind == IRGenLLVMLTOKind::Thin) {
+    EmitPasses.add(createBitcodeWriterPass(*RawOS));
-      EmitPasses.add(createWriteThinLTOBitcodePass(*RawOS));
-    } else {
-      EmitPasses.add(createBitcodeWriterPass(*RawOS));
-    }
     break;
-  }
   case IRGenOutputKind::NativeAssembly:
   case IRGenOutputKind::ObjectFile: {
     CodeGenFileType FileType;

lib/IRGen/IRGenModule.cpp

@@ -1098,18 +1098,10 @@ void IRGenModule::addLinkLibrary(const LinkLibrary &linkLib) {
   
   switch (linkLib.getKind()) {
   case LibraryKind::Library: {
-    if (TargetInfo.OutputObjectFormat == llvm::Triple::ELF && IRGen.Opts.LLVMLTOKind != IRGenLLVMLTOKind::None) {
+    llvm::SmallString<32> opt =
-      // When performing LTO, we always use lld that supports auto linking mechanism with ELF.
+        getTargetDependentLibraryOption(Triple, linkLib.getName());
-      // So embed dependent libraries names in "llvm.dependent-libraries" instead of options
+    AutolinkEntries.push_back(
-      // to avoid using swift-autolink-extract.
+        llvm::MDNode::get(ctx, llvm::MDString::get(ctx, opt)));
-      AutolinkEntries.push_back(
-          llvm::MDNode::get(ctx, llvm::MDString::get(ctx, linkLib.getName())));
-    } else {
-      llvm::SmallString<32> opt =
-          getTargetDependentLibraryOption(Triple, linkLib.getName());
-      AutolinkEntries.push_back(
-          llvm::MDNode::get(ctx, llvm::MDString::get(ctx, opt)));
-    }
     break;
   }
   case LibraryKind::Framework: {
@@ -1196,12 +1188,7 @@ static bool isFirstObjectFileInModule(IRGenModule &IGM) {
 void IRGenModule::emitAutolinkInfo() {
   // Collect the linker options already in the module (from ClangCodeGen).
   // FIXME: This constant should be vended by LLVM somewhere.
-  // When performing LTO, we always use lld that supports auto linking mechanism with ELF.
+  auto *Metadata = Module.getOrInsertNamedMetadata("llvm.linker.options");
-  // So embed dependent libraries names in "llvm.dependent-libraries" instead of "llvm.linker.options".
-  const StringRef AutolinkSectionName =
-      TargetInfo.OutputObjectFormat == llvm::Triple::ELF && IRGen.Opts.LLVMLTOKind != IRGenLLVMLTOKind::None
-        ? "llvm.dependent-libraries" : "llvm.linker.options";
-  auto *Metadata = Module.getOrInsertNamedMetadata(AutolinkSectionName);
   for (llvm::MDNode *LinkOption : Metadata->operands())
     AutolinkEntries.push_back(LinkOption);
 
@@ -1216,9 +1203,9 @@ void IRGenModule::emitAutolinkInfo() {
                         AutolinkEntries.end());
 
   const bool AutolinkExtractRequired =
-      ((TargetInfo.OutputObjectFormat == llvm::Triple::ELF && !Triple.isPS4()) ||
+      (TargetInfo.OutputObjectFormat == llvm::Triple::ELF && !Triple.isPS4()) ||
       TargetInfo.OutputObjectFormat == llvm::Triple::Wasm ||
-      Triple.isOSCygMing()) && IRGen.Opts.LLVMLTOKind == IRGenLLVMLTOKind::None;
+      Triple.isOSCygMing();
 
   if (!AutolinkExtractRequired) {
     // On platforms that support autolinking, continue to use the metadata.

test/Driver/Inputs/lto/lib.swift

@@ -1 +0,0 @@
-public func libraryFunction() {}

test/Driver/Inputs/lto/main.swift

@@ -1,3 +0,0 @@
-import A
-
-libraryFunction()

test/Driver/Inputs/lto/multifiles/file.swift

@@ -1,3 +0,0 @@
-func anotherFileFunction() {
-  print(#function)
-}

test/Driver/Inputs/lto/multifiles/main.swift

@@ -1 +0,0 @@
-anotherFileFunction()

test/Driver/link-time-opt-lib-thin.swift

@@ -1,12 +0,0 @@
-// FIXME: ld64 in Xcode toolchain uses older version of LLVM than swiftc, so ld64 can't read module summary for LTO 
-//        from bitcode file produced by compiler. This should be fixed before shipping Xcode toolchain by upgrading
-//        LLVM version used in ld64.
-// XFAIL: OS=macosx
-// XFAIL: OS=tvos
-// XFAIL: OS=watchos
-// XFAIL: OS=ios
-// RUN: rm -rf %t
-// RUN: %empty-directory(%t/thin)
-
-// RUN: %target-swiftc_driver %S/Inputs/lto/lib.swift -lto=llvm -emit-library -emit-module -module-name A -working-directory %t/thin
-// RUN: %target-swiftc_driver %S/Inputs/lto/main.swift -L. -I. -lA -lto=llvm -working-directory %t/thin

test/Driver/link-time-opt-lib.swift

@@ -1,5 +0,0 @@
-// RUN: rm -rf %t
-// RUN: %empty-directory(%t/full)
-
-// RUN: %target-swiftc_driver %S/Inputs/lto/lib.swift -lto=llvm-full -emit-library -emit-module -module-name A -working-directory %t/full
-// RUN: %target-swiftc_driver %S/Inputs/lto/main.swift -L. -I. -lA -lto=llvm-full -working-directory %t/full

test/Driver/link-time-opt-staticlib-thin.swift

@@ -1,14 +0,0 @@
-// UNSUPPORTED: OS=windows-msvc
-// FIXME: ld64 in Xcode toolchain uses older version of LLVM than swiftc, so ld64 can't read module summary for LTO 
-//        from bitcode file produced by compiler. This should be fixed before shipping Xcode toolchain by upgrading
-//        LLVM version used in ld64.
-// XFAIL: OS=macosx
-// XFAIL: OS=tvos
-// XFAIL: OS=watchos
-// XFAIL: OS=ios
-
-// RUN: rm -rf %t
-// RUN: %empty-directory(%t/thin-static)
-
-// RUN: %target-swiftc_driver %S/Inputs/lto/lib.swift -static -lto=llvm -emit-library -emit-module -module-name A -working-directory %t/thin-static
-// RUN: %target-swiftc_driver %S/Inputs/lto/main.swift -L. -I. -lA -lto=llvm -working-directory %t/thin-static

test/Driver/link-time-opt-staticlib.swift

@@ -1,6 +0,0 @@
-// UNSUPPORTED: OS=windows-msvc
-// RUN: rm -rf %t
-// RUN: %empty-directory(%t/full-static)
-
-// RUN: %target-swiftc_driver %S/Inputs/lto/lib.swift -static -lto=llvm-full -emit-library -emit-module -module-name A -working-directory %t/full-static
-// RUN: %target-swiftc_driver %S/Inputs/lto/main.swift -L. -I. -lA -lto=llvm-full -working-directory %t/full-static

test/Driver/link-time-opt.swift

@@ -1,5 +0,0 @@
-// RUN: %target-swiftc_driver -driver-print-jobs %S/../Inputs/empty.swift -lto=llvm | %FileCheck %s --check-prefix=CHECK-%target-os --check-prefix=CHECK
-// CHECK: swift{{(c\.exe")?}} -frontend -emit-bc
-// CHECK-macosx-NEXT: bin/ld {{.+}} -lto_library {{.+}}/lib/libLTO.dylib
-// CHECK-windows-msvc-NEXT: clang.exe" {{.+}} -fuse-ld=lld -flto=thin
-// CHECK-linux-gnu-NEXT: bin/clang {{.+}} -flto=thin

utils/build-windows.bat

@@ -97,7 +97,6 @@ git clone --depth 1 --single-branch https://github.com/apple/swift-cmark cmark %
 git clone --depth 1 --single-branch --branch swift/master https://github.com/apple/llvm-project llvm-project %exitOnError%
 mklink /D "%source_root%\clang" "%source_root%\llvm-project\clang"
 mklink /D "%source_root%\llvm" "%source_root%\llvm-project\llvm"
-mklink /D "%source_root%\lld" "%source_root%\llvm-project\lld"
 mklink /D "%source_root%\lldb" "%source_root%\llvm-project\lldb"
 mklink /D "%source_root%\compiler-rt" "%source_root%\llvm-project\compiler-rt"
 mklink /D "%source_root%\libcxx" "%source_root%\llvm-project\libcxx"
@@ -166,7 +165,7 @@ cmake^
     -DLLVM_DEFAULT_TARGET_TRIPLE=x86_64-unknown-windows-msvc^
     -DLLVM_ENABLE_PDB:BOOL=YES^
     -DLLVM_ENABLE_ASSERTIONS:BOOL=YES^
-    -DLLVM_ENABLE_PROJECTS:STRING=lld;clang^
+    -DLLVM_ENABLE_PROJECTS:STRING=clang^
     -DLLVM_TARGETS_TO_BUILD:STRING="AArch64;ARM;X86"^
     -DLLVM_INCLUDE_BENCHMARKS:BOOL=NO^
     -DLLVM_INCLUDE_DOCS:BOOL=NO^