[Clang] Remove support for legacy pass manager

[nikic]

Summary

This removes the -flegacy-pass-manager and -fno-experimental-new-pass-manager options, and the corresponding support code in BackendUtil. The -fno-legacy-pass-manager and -fexperimental-new-pass-manager options are retained as no-ops.

[HaohaiWen]

Hi @nikic,
We recently noticed legacy PM was removed from many places.
Does community plan to remove legacy PM completely?
Do you know when will CG switch to new PM?
Thanks.

[nikic]

In D123609#3451320, @HaohaiWen wrote:

Hi @nikic,
We recently noticed legacy PM was removed from many places.
Does community plan to remove legacy PM completely?
Do you know when will CG switch to new PM?
Thanks.

At this time, the ability to run a middle-end optimization pipeline using the legacy pass manager (basically anything based on PassManagerBuilder) is being removed. The CodeGen pipeline continues to use the legacy pass manager at this time -- I'm not aware of anyone doing active migration work in that area.

[lenary]

In D123609#3451334, @nikic wrote:

In D123609#3451320, @HaohaiWen wrote:

Hi @nikic,
We recently noticed legacy PM was removed from many places.
Does community plan to remove legacy PM completely?
Do you know when will CG switch to new PM?
Thanks.

At this time, the ability to run a middle-end optimization pipeline using the legacy pass manager (basically anything based on PassManagerBuilder) is being removed. The CodeGen pipeline continues to use the legacy pass manager at this time -- I'm not aware of anyone doing active migration work in that area.

Sorry to resurrect an old patch, but can you please update the docs here https://llvm.org/docs/NewPassManager.html#status-of-the-new-and-legacy-pass-managers with this info?

clang/include/clang/Basic/CodeGenOptions.def

 CODEGENOPT(DisableLLVMPasses , 1, 0) ///< Don't run any LLVM IR passes to get
                                      ///< the pristine IR generated by the
                                      ///< frontend.
 CODEGENOPT(DisableLifetimeMarkers, 1, 0) ///< Don't emit any lifetime markers
 CODEGENOPT(DisableO0ImplyOptNone , 1, 0) ///< Don't annonate function with optnone at O0
 CODEGENOPT(ExperimentalStrictFloatingPoint, 1, 0) ///< Enables the new, experimental
                                                   ///< strict floating point.
 CODEGENOPT(EnableNoundefAttrs, 1, 0) ///< Enable emitting `noundef` attributes on IR call arguments and return values
-CODEGENOPT(LegacyPassManager, 1, 0) ///< Use the legacy pass manager.
 CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
                                    ///< pass manager.
 CODEGENOPT(DisableRedZone    , 1, 0) ///< Set when -mno-red-zone is enabled.
 CODEGENOPT(EmitCallSiteInfo, 1, 0) ///< Emit call site info only in the case of
                                    ///< '-g' + 'O>0' level.
 CODEGENOPT(EnableDIPreservationVerify, 1, 0) ///< Enable di preservation verify
                                              ///< each (it means check
                                              ///< the original debug info

clang/include/clang/Driver/Options.td

 defm jmc : BoolFOption<"jmc",
   CodeGenOpts<"JMCInstrument">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option], "Enable just-my-code debugging">,
   NegFlag<SetFalse>>;
 def fglobal_isel : Flag<["-"], "fglobal-isel">, Group<f_clang_Group>,
   HelpText<"Enables the global instruction selector">;
 def fexperimental_isel : Flag<["-"], "fexperimental-isel">, Group<f_clang_Group>,
   Alias<fglobal_isel>;
-defm legacy_pass_manager : BoolOption<"f", "legacy-pass-manager",
-  CodeGenOpts<"LegacyPassManager">, DefaultFalse,
-  PosFlag<SetTrue>,
-  NegFlag<SetFalse>,
-  BothFlags<[CC1Option]>>, Group<f_clang_Group>;
+def fno_legacy_pass_manager : Flag<["-"], "fno-legacy-pass-manager">,
+  Group<f_clang_Group>, Flags<[CC1Option, NoArgumentUnused]>;
 def fexperimental_new_pass_manager : Flag<["-"], "fexperimental-new-pass-manager">,
   Group<f_clang_Group>, Flags<[CC1Option]>, Alias<fno_legacy_pass_manager>;
-def fno_experimental_new_pass_manager : Flag<["-"], "fno-experimental-new-pass-manager">,
-  Group<f_clang_Group>, Flags<[CC1Option,NoDriverOption]>, Alias<flegacy_pass_manager>;
 def fexperimental_strict_floating_point : Flag<["-"], "fexperimental-strict-floating-point">,
   Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Enables experimental strict floating point in LLVM.">,
   MarshallingInfoFlag<LangOpts<"ExpStrictFP">>;
 def finput_charset_EQ : Joined<["-"], "finput-charset=">, Flags<[FlangOption, FC1Option]>, Group<f_Group>,
   HelpText<"Specify the default character set for source files">;
 def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>;
 def finstrument_functions : Flag<["-"], "finstrument-functions">, Group<f_Group>, Flags<[CC1Option]>,

clang/lib/CodeGen/BackendUtil.cpp

 #include "llvm/Transforms/Coroutines.h"
 #include "llvm/Transforms/Coroutines/CoroCleanup.h"
 #include "llvm/Transforms/Coroutines/CoroEarly.h"
 #include "llvm/Transforms/Coroutines/CoroElide.h"
 #include "llvm/Transforms/Coroutines/CoroSplit.h"
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/AlwaysInliner.h"
 #include "llvm/Transforms/IPO/LowerTypeTests.h"
-#include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
 #include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
 #include "llvm/Transforms/Instrumentation/AddressSanitizerOptions.h"
 #include "llvm/Transforms/Instrumentation/BoundsChecking.h"
 #include "llvm/Transforms/Instrumentation/DataFlowSanitizer.h"
 #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
class EmitAssemblyHelper {
 
   TargetIRAnalysis getTargetIRAnalysis() const {
     if (TM)
       return TM->getTargetIRAnalysis();
 
     return TargetIRAnalysis();
   }
 
-  void CreatePasses(legacy::PassManager &MPM, legacy::FunctionPassManager &FPM);
-
   /// Generates the TargetMachine.
   /// Leaves TM unchanged if it is unable to create the target machine.
   /// Some of our clang tests specify triples which are not built
   /// into clang. This is okay because these tests check the generated
   /// IR, and they require DataLayout which depends on the triple.
   /// In this case, we allow this method to fail and not report an error.
   /// When MustCreateTM is used, we print an error if we are unable to load
   /// the requested target.
public:
 
   ~EmitAssemblyHelper() {
     if (CodeGenOpts.DisableFree)
       BuryPointer(std::move(TM));
   }
 
   std::unique_ptr<TargetMachine> TM;
 
-  // Emit output using the legacy pass manager for the optimization pipeline.
-  // This will be removed soon when using the legacy pass manager for the
-  // optimization pipeline is no longer supported.
-  void EmitAssemblyWithLegacyPassManager(BackendAction Action,
-                                         std::unique_ptr<raw_pwrite_stream> OS);
-
-  // Emit output using the new pass manager for the optimization pipeline. This
-  // is the default.
+  // Emit output using the new pass manager for the optimization pipeline.
   void EmitAssembly(BackendAction Action,
                     std::unique_ptr<raw_pwrite_stream> OS);
 };
-
-// We need this wrapper to access LangOpts and CGOpts from extension functions
-// that we add to the PassManagerBuilder.
-class PassManagerBuilderWrapper : public PassManagerBuilder {
-public:
-  PassManagerBuilderWrapper(const Triple &TargetTriple,
-                            const CodeGenOptions &CGOpts,
-                            const LangOptions &LangOpts)
-      : TargetTriple(TargetTriple), CGOpts(CGOpts), LangOpts(LangOpts) {}
-  const Triple &getTargetTriple() const { return TargetTriple; }
-  const CodeGenOptions &getCGOpts() const { return CGOpts; }
-  const LangOptions &getLangOpts() const { return LangOpts; }
-
-private:
-  const Triple &TargetTriple;
-  const CodeGenOptions &CGOpts;
-  const LangOptions &LangOpts;
-};
-}
-
-static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
-  if (Builder.OptLevel > 0)
-    PM.add(createObjCARCAPElimPass());
-}
-
-static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
-  if (Builder.OptLevel > 0)
-    PM.add(createObjCARCExpandPass());
-}
-
-static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
-  if (Builder.OptLevel > 0)
-    PM.add(createObjCARCOptPass());
-}
-
-static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
-                                     legacy::PassManagerBase &PM) {
-  PM.add(createAddDiscriminatorsPass());
-}
-
-static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
-                                  legacy::PassManagerBase &PM) {
-  PM.add(createBoundsCheckingLegacyPass());
 }
 
 static SanitizerCoverageOptions
 getSancovOptsFromCGOpts(const CodeGenOptions &CGOpts) {
   SanitizerCoverageOptions Opts;
   Opts.CoverageType =
       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
getSancovOptsFromCGOpts(const CodeGenOptions &CGOpts) {
   Opts.InlineBoolFlag = CGOpts.SanitizeCoverageInlineBoolFlag;
   Opts.PCTable = CGOpts.SanitizeCoveragePCTable;
   Opts.StackDepth = CGOpts.SanitizeCoverageStackDepth;
   Opts.TraceLoads = CGOpts.SanitizeCoverageTraceLoads;
   Opts.TraceStores = CGOpts.SanitizeCoverageTraceStores;
   return Opts;
 }
 
-static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
-                                     legacy::PassManagerBase &PM) {
-  const PassManagerBuilderWrapper &BuilderWrapper =
-      static_cast<const PassManagerBuilderWrapper &>(Builder);
-  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
-  auto Opts = getSancovOptsFromCGOpts(CGOpts);
-  PM.add(createModuleSanitizerCoverageLegacyPassPass(
-      Opts, CGOpts.SanitizeCoverageAllowlistFiles,
-      CGOpts.SanitizeCoverageIgnorelistFiles));
-}
-
 // Check if ASan should use GC-friendly instrumentation for globals.
 // First of all, there is no point if -fdata-sections is off (expect for MachO,
 // where this is not a factor). Also, on ELF this feature requires an assembler
 // extension that only works with -integrated-as at the moment.
 static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
   if (!CGOpts.SanitizeAddressGlobalsDeadStripping)
     return false;
   switch (T.getObjectFormat()) {
static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
   case Triple::Wasm:
   case Triple::DXContainer:
   case Triple::UnknownObjectFormat:
     break;
   }
   return false;
 }
 
-static void addMemProfilerPasses(const PassManagerBuilder &Builder,
-                                 legacy::PassManagerBase &PM) {
-  PM.add(createMemProfilerFunctionPass());
-  PM.add(createModuleMemProfilerLegacyPassPass());
-}
-
-static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
-                                      legacy::PassManagerBase &PM) {
-  const PassManagerBuilderWrapper &BuilderWrapper =
-      static_cast<const PassManagerBuilderWrapper&>(Builder);
-  const Triple &T = BuilderWrapper.getTargetTriple();
-  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
-  bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
-  bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
-  bool UseOdrIndicator = CGOpts.SanitizeAddressUseOdrIndicator;
-  bool UseGlobalsGC = asanUseGlobalsGC(T, CGOpts);
-  llvm::AsanDtorKind DestructorKind = CGOpts.getSanitizeAddressDtor();
-  llvm::AsanDetectStackUseAfterReturnMode UseAfterReturn =
-      CGOpts.getSanitizeAddressUseAfterReturn();
-  PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
-                                            UseAfterScope, UseAfterReturn));
-  PM.add(createModuleAddressSanitizerLegacyPassPass(
-      /*CompileKernel*/ false, Recover, UseGlobalsGC, UseOdrIndicator,
-      DestructorKind));
-}
-
-static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
-                                            legacy::PassManagerBase &PM) {
-  PM.add(createAddressSanitizerFunctionPass(
-      /*CompileKernel*/ true, /*Recover*/ true, /*UseAfterScope*/ false,
-      /*UseAfterReturn*/ llvm::AsanDetectStackUseAfterReturnMode::Never));
-  PM.add(createModuleAddressSanitizerLegacyPassPass(
-      /*CompileKernel*/ true, /*Recover*/ true, /*UseGlobalsGC*/ true,
-      /*UseOdrIndicator*/ false));
-}
-
-static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
-                                            legacy::PassManagerBase &PM) {
-  const PassManagerBuilderWrapper &BuilderWrapper =
-      static_cast<const PassManagerBuilderWrapper &>(Builder);
-  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
-  bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
-  PM.add(createHWAddressSanitizerLegacyPassPass(
-      /*CompileKernel*/ false, Recover,
-      /*DisableOptimization*/ CGOpts.OptimizationLevel == 0));
-}
-
-static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
-                                              legacy::PassManagerBase &PM) {
-  const PassManagerBuilderWrapper &BuilderWrapper =
-      static_cast<const PassManagerBuilderWrapper &>(Builder);
-  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
-  PM.add(createHWAddressSanitizerLegacyPassPass(
-      /*CompileKernel*/ true, /*Recover*/ true,
-      /*DisableOptimization*/ CGOpts.OptimizationLevel == 0));
-}
-
-static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
-                                             legacy::PassManagerBase &PM,
-                                             bool CompileKernel) {
-  const PassManagerBuilderWrapper &BuilderWrapper =
-      static_cast<const PassManagerBuilderWrapper&>(Builder);
-  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
-  int TrackOrigins = CGOpts.SanitizeMemoryTrackOrigins;
-  bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Memory);
-  PM.add(createMemorySanitizerLegacyPassPass(
-      MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel,
-                             CGOpts.SanitizeMemoryParamRetval != 0}));
-
-  // MemorySanitizer inserts complex instrumentation that mostly follows
-  // the logic of the original code, but operates on "shadow" values.
-  // It can benefit from re-running some general purpose optimization passes.
-  if (Builder.OptLevel > 0) {
-    PM.add(createEarlyCSEPass());
-    PM.add(createReassociatePass());
-    PM.add(createLICMPass());
-    PM.add(createGVNPass());
-    PM.add(createInstructionCombiningPass());
-    PM.add(createDeadStoreEliminationPass());
-  }
-}
-
-static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
-                                   legacy::PassManagerBase &PM) {
-  addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ false);
-}
-
-static void addKernelMemorySanitizerPass(const PassManagerBuilder &Builder,
-                                         legacy::PassManagerBase &PM) {
-  addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ true);
-}
-
-static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
-                                   legacy::PassManagerBase &PM) {
-  PM.add(createThreadSanitizerLegacyPassPass());
-}
-
-static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
-                                     legacy::PassManagerBase &PM) {
-  const PassManagerBuilderWrapper &BuilderWrapper =
-      static_cast<const PassManagerBuilderWrapper&>(Builder);
-  const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
-  PM.add(createDataFlowSanitizerLegacyPassPass(LangOpts.NoSanitizeFiles));
-}
-
-static void addEntryExitInstrumentationPass(const PassManagerBuilder &Builder,
-                                            legacy::PassManagerBase &PM) {
-  PM.add(createEntryExitInstrumenterPass());
-}
-
-static void
-addPostInlineEntryExitInstrumentationPass(const PassManagerBuilder &Builder,
-                                          legacy::PassManagerBase &PM) {
-  PM.add(createPostInlineEntryExitInstrumenterPass());
-}
-
 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
                                          const CodeGenOptions &CodeGenOpts) {
   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
 
   switch (CodeGenOpts.getVecLib()) {
   case CodeGenOptions::Accelerate:
     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
     break;
TLII->addVectorizableFunctionsFromVecLib(
         TargetLibraryInfoImpl::DarwinLibSystemM);
     break;
   default:
     break;
   }
   return TLII;
 }
 
-static void addSymbolRewriterPass(const CodeGenOptions &Opts,
-                                  legacy::PassManager *MPM) {
-  llvm::SymbolRewriter::RewriteDescriptorList DL;
-
-  llvm::SymbolRewriter::RewriteMapParser MapParser;
-  for (const auto &MapFile : Opts.RewriteMapFiles)
-    MapParser.parse(MapFile, &DL);
-
-  MPM->add(createRewriteSymbolsPass(DL));
-}
-
 static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
   switch (CodeGenOpts.OptimizationLevel) {
   default:
     llvm_unreachable("Invalid optimization level!");
   case 0:
     return CodeGenOpt::None;
   case 1:
     return CodeGenOpt::Less;
if (!CodeGenOpts.hasProfileClangInstr())
     return None;
   InstrProfOptions Options;
   Options.NoRedZone = CodeGenOpts.DisableRedZone;
   Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
   Options.Atomic = CodeGenOpts.AtomicProfileUpdate;
   return Options;
 }
 
-void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
-                                      legacy::FunctionPassManager &FPM) {
-  // Handle disabling of all LLVM passes, where we want to preserve the
-  // internal module before any optimization.
-  if (CodeGenOpts.DisableLLVMPasses)
-    return;
-
-  // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
-  // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
-  // are inserted before PMBuilder ones - they'd get the default-constructed
-  // TLI with an unknown target otherwise.
-  std::unique_ptr<TargetLibraryInfoImpl> TLII(
-      createTLII(TargetTriple, CodeGenOpts));
-
-  // If we reached here with a non-empty index file name, then the index file
-  // was empty and we are not performing ThinLTO backend compilation (used in
-  // testing in a distributed build environment). Drop any the type test
-  // assume sequences inserted for whole program vtables so that codegen doesn't
-  // complain.
-  if (!CodeGenOpts.ThinLTOIndexFile.empty())
-    MPM.add(createLowerTypeTestsPass(/*ExportSummary=*/nullptr,
-                                     /*ImportSummary=*/nullptr,
-                                     /*DropTypeTests=*/true));
-
-  PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
-
-  // At O0 and O1 we only run the always inliner which is more efficient. At
-  // higher optimization levels we run the normal inliner.
-  if (CodeGenOpts.OptimizationLevel <= 1) {
-    bool InsertLifetimeIntrinsics = ((CodeGenOpts.OptimizationLevel != 0 &&
-                                      !CodeGenOpts.DisableLifetimeMarkers) ||
-                                     LangOpts.Coroutines);
-    PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
-  } else {
-    // We do not want to inline hot callsites for SamplePGO module-summary build
-    // because profile annotation will happen again in ThinLTO backend, and we
-    // want the IR of the hot path to match the profile.
-    PMBuilder.Inliner = createFunctionInliningPass(
-        CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
-        (!CodeGenOpts.SampleProfileFile.empty() &&
-         CodeGenOpts.PrepareForThinLTO));
-  }
-
-  PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
-  PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
-  PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
-  PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
-  // Only enable CGProfilePass when using integrated assembler, since
-  // non-integrated assemblers don't recognize .cgprofile section.
-  PMBuilder.CallGraphProfile = !CodeGenOpts.DisableIntegratedAS;
-
-  PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
-  // Loop interleaving in the loop vectorizer has historically been set to be
-  // enabled when loop unrolling is enabled.
-  PMBuilder.LoopsInterleaved = CodeGenOpts.UnrollLoops;
-  PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
-  PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
-  PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
-  PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
-
-  MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
-
-  if (TM)
-    TM->adjustPassManager(PMBuilder);
-
-  if (CodeGenOpts.DebugInfoForProfiling ||
-      !CodeGenOpts.SampleProfileFile.empty())
-    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
-                           addAddDiscriminatorsPass);
-
-  // In ObjC ARC mode, add the main ARC optimization passes.
-  if (LangOpts.ObjCAutoRefCount) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
-                           addObjCARCExpandPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
-                           addObjCARCAPElimPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
-                           addObjCARCOptPass);
-  }
-
-  if (LangOpts.Coroutines)
-    addCoroutinePassesToExtensionPoints(PMBuilder);
-
-  if (!CodeGenOpts.MemoryProfileOutput.empty()) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addMemProfilerPasses);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addMemProfilerPasses);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
-                           addBoundsCheckingPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addBoundsCheckingPass);
-  }
-
-  if (CodeGenOpts.hasSanitizeCoverage()) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addSanitizerCoveragePass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addSanitizerCoveragePass);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addAddressSanitizerPasses);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addAddressSanitizerPasses);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addKernelAddressSanitizerPasses);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addKernelAddressSanitizerPasses);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addHWAddressSanitizerPasses);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addHWAddressSanitizerPasses);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addKernelHWAddressSanitizerPasses);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addKernelHWAddressSanitizerPasses);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addMemorySanitizerPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addMemorySanitizerPass);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addKernelMemorySanitizerPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addKernelMemorySanitizerPass);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addThreadSanitizerPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addThreadSanitizerPass);
-  }
-
-  if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addDataFlowSanitizerPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addDataFlowSanitizerPass);
-  }
-
-  if (CodeGenOpts.InstrumentFunctions ||
-      CodeGenOpts.InstrumentFunctionEntryBare ||
-      CodeGenOpts.InstrumentFunctionsAfterInlining ||
-      CodeGenOpts.InstrumentForProfiling) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
-                           addEntryExitInstrumentationPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addEntryExitInstrumentationPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
-                           addPostInlineEntryExitInstrumentationPass);
-    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
-                           addPostInlineEntryExitInstrumentationPass);
-  }
-
-  // Set up the per-function pass manager.
-  FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
-  if (CodeGenOpts.VerifyModule)
-    FPM.add(createVerifierPass());
-
-  // Set up the per-module pass manager.
-  if (!CodeGenOpts.RewriteMapFiles.empty())
-    addSymbolRewriterPass(CodeGenOpts, &MPM);
-
-  if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts, LangOpts)) {
-    MPM.add(createGCOVProfilerPass(*Options));
-    if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
-      MPM.add(createStripSymbolsPass(true));
-  }
-
-  if (Optional<InstrProfOptions> Options =
-          getInstrProfOptions(CodeGenOpts, LangOpts))
-    MPM.add(createInstrProfilingLegacyPass(*Options, false));
-
-  bool hasIRInstr = false;
-  if (CodeGenOpts.hasProfileIRInstr()) {
-    PMBuilder.EnablePGOInstrGen = true;
-    hasIRInstr = true;
-  }
-  if (CodeGenOpts.hasProfileCSIRInstr()) {
-    assert(!CodeGenOpts.hasProfileCSIRUse() &&
-           "Cannot have both CSProfileUse pass and CSProfileGen pass at the "
-           "same time");
-    assert(!hasIRInstr &&
-           "Cannot have both ProfileGen pass and CSProfileGen pass at the "
-           "same time");
-    PMBuilder.EnablePGOCSInstrGen = true;
-    hasIRInstr = true;
-  }
-  if (hasIRInstr) {
-    if (!CodeGenOpts.InstrProfileOutput.empty())
-      PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
-    else
-      PMBuilder.PGOInstrGen = getDefaultProfileGenName();
-  }
-  if (CodeGenOpts.hasProfileIRUse()) {
-    PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
-    PMBuilder.EnablePGOCSInstrUse = CodeGenOpts.hasProfileCSIRUse();
-  }
-
-  if (!CodeGenOpts.SampleProfileFile.empty())
-    PMBuilder.PGOSampleUse = CodeGenOpts.SampleProfileFile;
-
-  PMBuilder.populateFunctionPassManager(FPM);
-  PMBuilder.populateModulePassManager(MPM);
-}
-
 static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) {
   SmallVector<const char *, 16> BackendArgs;
   BackendArgs.push_back("clang"); // Fake program name.
   if (!CodeGenOpts.DebugPass.empty()) {
     BackendArgs.push_back("-debug-pass");
     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
   }
   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
if (TM->addPassesToEmitFile(CodeGenPasses, OS, DwoOS, CGFT,
                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
     Diags.Report(diag::err_fe_unable_to_interface_with_target);
     return false;
   }
 
   return true;
 }
 
-void EmitAssemblyHelper::EmitAssemblyWithLegacyPassManager(
-    BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
-  TimeRegion Region(CodeGenOpts.TimePasses ? &CodeGenerationTime : nullptr);
-
-  setCommandLineOpts(CodeGenOpts);
-
-  bool UsesCodeGen = actionRequiresCodeGen(Action);
-  CreateTargetMachine(UsesCodeGen);
-
-  if (UsesCodeGen && !TM)
-    return;
-  if (TM)
-    TheModule->setDataLayout(TM->createDataLayout());
-
-  DebugifyCustomPassManager PerModulePasses;
-  DebugInfoPerPass DebugInfoBeforePass;
-  if (CodeGenOpts.EnableDIPreservationVerify) {
-    PerModulePasses.setDebugifyMode(DebugifyMode::OriginalDebugInfo);
-    PerModulePasses.setDebugInfoBeforePass(DebugInfoBeforePass);
-
-    if (!CodeGenOpts.DIBugsReportFilePath.empty())
-      PerModulePasses.setOrigDIVerifyBugsReportFilePath(
-          CodeGenOpts.DIBugsReportFilePath);
-  }
-  PerModulePasses.add(
-      createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
-
-  legacy::FunctionPassManager PerFunctionPasses(TheModule);
-  PerFunctionPasses.add(
-      createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
-
-  CreatePasses(PerModulePasses, PerFunctionPasses);
-
-  // Add a verifier pass if requested. We don't have to do this if the action
-  // requires code generation because there will already be a verifier pass in
-  // the code-generation pipeline.
-  if (!UsesCodeGen && CodeGenOpts.VerifyModule)
-    PerModulePasses.add(createVerifierPass());
-
-  legacy::PassManager CodeGenPasses;
-  CodeGenPasses.add(
-      createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
-
-  std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
-
-  switch (Action) {
-  case Backend_EmitNothing:
-    break;
-
-  case Backend_EmitBC:
-    if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
-      if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
-        ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
-        if (!ThinLinkOS)
-          return;
-      }
-      if (!TheModule->getModuleFlag("EnableSplitLTOUnit"))
-        TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
-                                 CodeGenOpts.EnableSplitLTOUnit);
-      PerModulePasses.add(createWriteThinLTOBitcodePass(
-          *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
-    } else {
-      // Emit a module summary by default for Regular LTO except for ld64
-      // targets
-      bool EmitLTOSummary = shouldEmitRegularLTOSummary();
-      if (EmitLTOSummary) {
-        if (!TheModule->getModuleFlag("ThinLTO"))
-          TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
-        if (!TheModule->getModuleFlag("EnableSplitLTOUnit"))
-          TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
-                                   uint32_t(1));
-      }
-      PerModulePasses.add(createBitcodeWriterPass(
-          *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
-    }
-    break;
-
-  case Backend_EmitLL:
-    PerModulePasses.add(
-        createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
-    break;
-
-  default:
-    if (!CodeGenOpts.SplitDwarfOutput.empty()) {
-      DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
-      if (!DwoOS)
-        return;
-    }
-    if (!AddEmitPasses(CodeGenPasses, Action, *OS,
-                       DwoOS ? &DwoOS->os() : nullptr))
-      return;
-  }
-
-  // Before executing passes, print the final values of the LLVM options.
-  cl::PrintOptionValues();
-
-  // Run passes. For now we do all passes at once, but eventually we
-  // would like to have the option of streaming code generation.
-
-  {
-    PrettyStackTraceString CrashInfo("Per-function optimization");
-    llvm::TimeTraceScope TimeScope("PerFunctionPasses");
-
-    PerFunctionPasses.doInitialization();
-    for (Function &F : *TheModule)
-      if (!F.isDeclaration())
-        PerFunctionPasses.run(F);
-    PerFunctionPasses.doFinalization();
-  }
-
-  {
-    PrettyStackTraceString CrashInfo("Per-module optimization passes");
-    llvm::TimeTraceScope TimeScope("PerModulePasses");
-    PerModulePasses.run(*TheModule);
-  }
-
-  {
-    PrettyStackTraceString CrashInfo("Code generation");
-    llvm::TimeTraceScope TimeScope("CodeGenPasses");
-    CodeGenPasses.run(*TheModule);
-  }
-
-  if (ThinLinkOS)
-    ThinLinkOS->keep();
-  if (DwoOS)
-    DwoOS->keep();
-}
-
 static OptimizationLevel mapToLevel(const CodeGenOptions &Opts) {
   switch (Opts.OptimizationLevel) {
   default:
     llvm_unreachable("Invalid optimization level!");
 
   case 0:
     return OptimizationLevel::O0;
 
void EmitAssemblyHelper::RunCodegenPipeline(
 
   {
     PrettyStackTraceString CrashInfo("Code generation");
     llvm::TimeTraceScope TimeScope("CodeGenPasses");
     CodeGenPasses.run(*TheModule);
   }
 }
 
-/// A clean version of `EmitAssembly` that uses the new pass manager.
-///
-/// Not all features are currently supported in this system, but where
-/// necessary it falls back to the legacy pass manager to at least provide
-/// basic functionality.
-///
-/// This API is planned to have its functionality finished and then to replace
-/// `EmitAssembly` at some point in the future when the default switches.
 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
                                       std::unique_ptr<raw_pwrite_stream> OS) {
   TimeRegion Region(CodeGenOpts.TimePasses ? &CodeGenerationTime : nullptr);
   setCommandLineOpts(CodeGenOpts);
 
   bool RequiresCodeGen = actionRequiresCodeGen(Action);
   CreateTargetMachine(RequiresCodeGen);
 
if (CGOpts.hasProfileCSIRInstr()) {
     Conf.RunCSIRInstr = true;
     Conf.CSIRProfile = std::move(CGOpts.InstrProfileOutput);
   } else if (CGOpts.hasProfileCSIRUse()) {
     Conf.RunCSIRInstr = false;
     Conf.CSIRProfile = std::move(CGOpts.ProfileInstrumentUsePath);
   }
 
   Conf.ProfileRemapping = std::move(ProfileRemapping);
-  Conf.UseNewPM = !CGOpts.LegacyPassManager;
   Conf.DebugPassManager = CGOpts.DebugPassManager;
   Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
   Conf.RemarksFilename = CGOpts.OptRecordFile;
   Conf.RemarksPasses = CGOpts.OptRecordPasses;
   Conf.RemarksFormat = CGOpts.OptRecordFormat;
   Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
   Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
   switch (Action) {
if (CombinedIndex) {
       // information.
       EmptyModule = std::make_unique<llvm::Module>("empty", M->getContext());
       EmptyModule->setTargetTriple(M->getTargetTriple());
       M = EmptyModule.get();
     }
   }
 
   EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
-
-  if (CGOpts.LegacyPassManager)
-    AsmHelper.EmitAssemblyWithLegacyPassManager(Action, std::move(OS));
-  else
-    AsmHelper.EmitAssembly(Action, std::move(OS));
 
   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
   // DataLayout.
   if (AsmHelper.TM) {
     std::string DLDesc = M->getDataLayout().getStringRepresentation();
     if (DLDesc != TDesc) {
       unsigned DiagID = Diags.getCustomDiagID(
           DiagnosticsEngine::Error, "backend data layout '%0' does not match "

clang/lib/Driver/ToolChains/Clang.cpp

if (Args.hasFlag(options::OPT_fpch_instantiate_templates,
     CmdArgs.push_back("-fpch-instantiate-templates");
   if (Args.hasFlag(options::OPT_fpch_codegen, options::OPT_fno_pch_codegen,
                    false))
     CmdArgs.push_back("-fmodules-codegen");
   if (Args.hasFlag(options::OPT_fpch_debuginfo, options::OPT_fno_pch_debuginfo,
                    false))
     CmdArgs.push_back("-fmodules-debuginfo");
 
-  Args.AddLastArg(CmdArgs, options::OPT_flegacy_pass_manager,
-                  options::OPT_fno_legacy_pass_manager);
-
   ObjCRuntime Runtime = AddObjCRuntimeArgs(Args, Inputs, CmdArgs, rewriteKind);
   RenderObjCOptions(TC, D, RawTriple, Args, Runtime, rewriteKind != RK_None,
                     Input, CmdArgs);
 
   if (types::isObjC(Input.getType()) &&
       Args.hasFlag(options::OPT_fobjc_encode_cxx_class_template_spec,
                    options::OPT_fno_objc_encode_cxx_class_template_spec,
                    !Runtime.isNeXTFamily()))

clang/lib/Driver/ToolChains/CommonArgs.cpp

if (CSPGOGenerateArg) {
     SmallString<128> Path(
         ProfileUseArg->getNumValues() == 0 ? "" : ProfileUseArg->getValue());
     if (Path.empty() || llvm::sys::fs::is_directory(Path))
       llvm::sys::path::append(Path, "default.profdata");
     CmdArgs.push_back(Args.MakeArgString(Twine("-plugin-opt=cs-profile-path=") +
                                          Path));
   }
 
-  // Pass an option to enable/disable the new pass manager.
-  if (auto *A = Args.getLastArg(options::OPT_flegacy_pass_manager,
-                                options::OPT_fno_legacy_pass_manager)) {
-    if (A->getOption().matches(options::OPT_flegacy_pass_manager))
-      CmdArgs.push_back("-plugin-opt=legacy-pass-manager");
-    else
-      CmdArgs.push_back("-plugin-opt=new-pass-manager");
-  }
-
   // Setup statistics file output.
   SmallString<128> StatsFile = getStatsFileName(Args, Output, Input, D);
   if (!StatsFile.empty())
     CmdArgs.push_back(
         Args.MakeArgString(Twine("-plugin-opt=stats-file=") + StatsFile));
 
   addX86AlignBranchArgs(D, Args, CmdArgs, /*IsLTO=*/true);
 

clang/lib/Frontend/CompilerInvocation.cpp

if (Arg *A = Args.getLastArg(OPT_fdefault_calling_conv_EQ)) {
     emitError |= (DefaultCC == LangOptions::DCC_VectorCall ||
                   DefaultCC == LangOptions::DCC_RegCall) &&
                  !T.isX86();
     if (emitError)
       Diags.Report(diag::err_drv_argument_not_allowed_with)
           << A->getSpelling() << T.getTriple();
   }
 
-  if (!CodeGenOpts.ProfileRemappingFile.empty() && CodeGenOpts.LegacyPassManager)
-    Diags.Report(diag::err_drv_argument_only_allowed_with)
-        << Args.getLastArg(OPT_fprofile_remapping_file_EQ)->getAsString(Args)
-        << "-fno-legacy-pass-manager";
-
   return Diags.getNumErrors() == NumErrorsBefore;
 }
 
 //===----------------------------------------------------------------------===//
 // Deserialization (from args)
 //===----------------------------------------------------------------------===//
 
 static unsigned getOptimizationLevel(ArgList &Args, InputKind IK,
#undef CODEGEN_OPTION_WITH_MARSHALLING
   if (!Opts.ProfileInstrumentUsePath.empty())
     setPGOUseInstrumentor(Opts, Opts.ProfileInstrumentUsePath);
 
   if (const Arg *A = Args.getLastArg(OPT_ftime_report, OPT_ftime_report_EQ)) {
     Opts.TimePasses = true;
 
     // -ftime-report= is only for new pass manager.
     if (A->getOption().getID() == OPT_ftime_report_EQ) {
-      if (Opts.LegacyPassManager)
-        Diags.Report(diag::err_drv_argument_only_allowed_with)
-            << A->getAsString(Args) << "-fno-legacy-pass-manager";
-
       StringRef Val = A->getValue();
       if (Val == "per-pass")
         Opts.TimePassesPerRun = false;
       else if (Val == "per-pass-run")
         Opts.TimePassesPerRun = true;
       else
         Diags.Report(diag::err_drv_invalid_value)
             << A->getAsString(Args) << A->getValue();

clang/test/Driver/flegacy-pass-manager.c

-// RUN: %clang -### -c -flegacy-pass-manager -fno-legacy-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,NEW %s
-// RUN: %clang -### -c -fno-legacy-pass-manager -flegacy-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,LEGACY %s
+/// -fno-legacy-pass-manager and -fexperimental-new-pass-manager are retained
+// as no-ops. The inverted options are no longer supported.
 
-/// -fexperimental-new-pass-manager is a legacy alias. -fno-experimental-new-pass-manager has been removed.
-// RUN: %clang -### -c -fexperimental-new-pass-manager %s 2>&1 | FileCheck --check-prefixes=NOWARN,NEW %s
-// RUN: not %clang -### -fno-experimental-new-pass-manager %s
-
-// NOWARN-NOT: warning: argument unused
-
-// NEW:        -fno-legacy-pass-manager
-// NEW-NOT:    -flegacy-pass-manager
-
-// LEGACY:     -flegacy-pass-manager
-// LEGACY-NOT: -fno-legacy-pass-manager
+// RUN: %clang -### -c -fno-legacy-pass-manager %s 2>&1 | FileCheck %s
+// RUN: not %clang -### -flegacy-pass-manager %s
 
-/// For full/Thin LTO, -fno-legacy-pass-manager passes -plugin-opt=new-pass-manager to the linker (which may not be LLD).
-// RUN: %clang -### -target x86_64-linux -flto -fno-legacy-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_NEW %s
-// RUN: %clang -### -target x86_64-linux -flto=thin -fexperimental-new-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_NEW %s
-
-// LTO_NEW:    "-plugin-opt=new-pass-manager"
-
-// RUN: %clang -### -target x86_64-linux -flto -flegacy-pass-manager %s 2>&1 | FileCheck --check-prefix=LTO_LEGACY %s
+// RUN: %clang -### -c -fexperimental-new-pass-manager %s 2>&1 | FileCheck %s
+// RUN: not %clang -### -fno-experimental-new-pass-manager %s
 
-// LTO_LEGACY: "-plugin-opt=legacy-pass-manager"
+// Just check that there is no argument unused warning. There is no need to
+// pass any cc1 options.
 
-// RUN: %clang -### -target x86_64-linux -flto %s 2>&1 | FileCheck --check-prefix=DEFAULT %s
-//
-// DEFAULT-NOT: "-plugin-opt=new-pass-manager"
-// DEFAULT-NOT: "-plugin-opt=legacy-pass-manager"
+// CHECK-NOT: warning: argument unused