tools/llc/llc.cpp

   1 //===-- llc.cpp - Implement the LLVM Native Code Generator ----------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This is the llc code generator driver. It provides a convenient
  10 // command-line interface for generating native assembly-language code
  11 // or C code, given LLVM bitcode.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/ADT/STLExtras.h"
  16 #include "llvm/ADT/Triple.h"
  17 #include "llvm/Analysis/TargetLibraryInfo.h"
  18 #include "llvm/CodeGen/CommandFlags.inc"
  19 #include "llvm/CodeGen/LinkAllAsmWriterComponents.h"
  20 #include "llvm/CodeGen/LinkAllCodegenComponents.h"
  21 #include "llvm/CodeGen/MIRParser/MIRParser.h"
  22 #include "llvm/CodeGen/MachineFunctionPass.h"
  23 #include "llvm/CodeGen/MachineModuleInfo.h"
  24 #include "llvm/CodeGen/TargetPassConfig.h"
  25 #include "llvm/CodeGen/TargetSubtargetInfo.h"
  26 #include "llvm/IR/AutoUpgrade.h"
  27 #include "llvm/IR/DataLayout.h"
  28 #include "llvm/IR/DiagnosticInfo.h"
  29 #include "llvm/IR/DiagnosticPrinter.h"
  30 #include "llvm/IR/IRPrintingPasses.h"
  31 #include "llvm/IR/LLVMContext.h"
  32 #include "llvm/IR/LegacyPassManager.h"
  33 #include "llvm/IR/Module.h"
  34 #include "llvm/IR/RemarkStreamer.h"
  35 #include "llvm/IR/Verifier.h"
  36 #include "llvm/IRReader/IRReader.h"
  37 #include "llvm/MC/SubtargetFeature.h"
  38 #include "llvm/Pass.h"
  39 #include "llvm/Support/CommandLine.h"
  40 #include "llvm/Support/Debug.h"
  41 #include "llvm/Support/FileSystem.h"
  42 #include "llvm/Support/FormattedStream.h"
  43 #include "llvm/Support/Host.h"
  44 #include "llvm/Support/InitLLVM.h"
  45 #include "llvm/Support/ManagedStatic.h"
  46 #include "llvm/Support/PluginLoader.h"
  47 #include "llvm/Support/SourceMgr.h"
  48 #include "llvm/Support/TargetRegistry.h"
  49 #include "llvm/Support/TargetSelect.h"
  50 #include "llvm/Support/ToolOutputFile.h"
  51 #include "llvm/Support/WithColor.h"
  52 #include "llvm/Target/TargetMachine.h"
  53 #include "llvm/Transforms/Utils/Cloning.h"
  54 #include <memory>
  55 using namespace llvm;
  56
  57 // General options for llc.  Other pass-specific options are specified
  58 // within the corresponding llc passes, and target-specific options
  59 // and back-end code generation options are specified with the target machine.
  60 //
  61 static cl::opt<std::string>
  62 InputFilename(cl::Positional, cl::desc("<input bitcode>"), cl::init("-"));
  63
  64 static cl::opt<std::string>
  65 InputLanguage("x", cl::desc("Input language ('ir' or 'mir')"));
  66
  67 static cl::opt<std::string>
  68 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"));
  69
  70 static cl::opt<std::string>
  71     SplitDwarfOutputFile("split-dwarf-output",
  72                          cl::desc(".dwo output filename"),
  73                          cl::value_desc("filename"));
  74
  75 static cl::opt<unsigned>
  76 TimeCompilations("time-compilations", cl::Hidden, cl::init(1u),
  77                  cl::value_desc("N"),
  78                  cl::desc("Repeat compilation N times for timing"));
  79
  80 static cl::opt<bool>
  81 NoIntegratedAssembler("no-integrated-as", cl::Hidden,
  82                       cl::desc("Disable integrated assembler"));
  83
  84 static cl::opt<bool>
  85     PreserveComments("preserve-as-comments", cl::Hidden,
  86                      cl::desc("Preserve Comments in outputted assembly"),
  87                      cl::init(true));
  88
  89 // Determine optimization level.
  90 static cl::opt<char>
  91 OptLevel("O",
  92          cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
  93                   "(default = '-O2')"),
  94          cl::Prefix,
  95          cl::ZeroOrMore,
  96          cl::init(' '));
  97
  98 static cl::opt<std::string>
  99 TargetTriple("mtriple", cl::desc("Override target triple for module"));
 100
 101 static cl::opt<std::string> SplitDwarfFile(
 102     "split-dwarf-file",
 103     cl::desc(
 104         "Specify the name of the .dwo file to encode in the DWARF output"));
 105
 106 static cl::opt<bool> NoVerify("disable-verify", cl::Hidden,
 107                               cl::desc("Do not verify input module"));
 108
 109 static cl::opt<bool> DisableSimplifyLibCalls("disable-simplify-libcalls",
 110                                              cl::desc("Disable simplify-libcalls"));
 111
 112 static cl::opt<bool> ShowMCEncoding("show-mc-encoding", cl::Hidden,
 113                                     cl::desc("Show encoding in .s output"));
 114
 115 static cl::opt<bool> EnableDwarfDirectory(
 116     "enable-dwarf-directory", cl::Hidden,
 117     cl::desc("Use .file directives with an explicit directory."));
 118
 119 static cl::opt<bool> AsmVerbose("asm-verbose",
 120                                 cl::desc("Add comments to directives."),
 121                                 cl::init(true));
 122
 123 static cl::opt<bool>
 124     CompileTwice("compile-twice", cl::Hidden,
 125                  cl::desc("Run everything twice, re-using the same pass "
 126                           "manager and verify the result is the same."),
 127                  cl::init(false));
 128
 129 static cl::opt<bool> DiscardValueNames(
 130     "discard-value-names",
 131     cl::desc("Discard names from Value (other than GlobalValue)."),
 132     cl::init(false), cl::Hidden);
 133
 134 static cl::list<std::string> IncludeDirs("I", cl::desc("include search path"));
 135
 136 static cl::opt<bool> RemarksWithHotness(
 137     "pass-remarks-with-hotness",
 138     cl::desc("With PGO, include profile count in optimization remarks"),
 139     cl::Hidden);
 140
 141 static cl::opt<unsigned>
 142     RemarksHotnessThreshold("pass-remarks-hotness-threshold",
 143                             cl::desc("Minimum profile count required for "
 144                                      "an optimization remark to be output"),
 145                             cl::Hidden);
 146
 147 static cl::opt<std::string>
 148     RemarksFilename("pass-remarks-output",
 149                     cl::desc("Output filename for pass remarks"),
 150                     cl::value_desc("filename"));
 151
 152 static cl::opt<std::string>
 153     RemarksPasses("pass-remarks-filter",
 154                   cl::desc("Only record optimization remarks from passes whose "
 155                            "names match the given regular expression"),
 156                   cl::value_desc("regex"));
 157
 158 static cl::opt<std::string> RemarksFormat(
 159     "pass-remarks-format",
 160     cl::desc("The format used for serializing remarks (default: YAML)"),
 161     cl::value_desc("format"), cl::init("yaml"));
 162
 163 namespace {
 164 static ManagedStatic<std::vector<std::string>> RunPassNames;
 165
 166 struct RunPassOption {
 167   void operator=(const std::string &Val) const {
 168     if (Val.empty())
 169       return;
 170     SmallVector<StringRef, 8> PassNames;
 171     StringRef(Val).split(PassNames, ',', -1, false);
 172     for (auto PassName : PassNames)
 173       RunPassNames->push_back(PassName);
 174   }
 175 };
 176 }
 177
 178 static RunPassOption RunPassOpt;
 179
 180 static cl::opt<RunPassOption, true, cl::parser<std::string>> RunPass(
 181     "run-pass",
 182     cl::desc("Run compiler only for specified passes (comma separated list)"),
 183     cl::value_desc("pass-name"), cl::ZeroOrMore, cl::location(RunPassOpt));
 184
 185 static int compileModule(char **, LLVMContext &);
 186
 187 static std::unique_ptr<ToolOutputFile> GetOutputStream(const char *TargetName,
 188                                                        Triple::OSType OS,
 189                                                        const char *ProgName) {
 190   // If we don't yet have an output filename, make one.
 191   if (OutputFilename.empty()) {
 192     if (InputFilename == "-")
 193       OutputFilename = "-";
 194     else {
 195       // If InputFilename ends in .bc or .ll, remove it.
 196       StringRef IFN = InputFilename;
 197       if (IFN.endswith(".bc") || IFN.endswith(".ll"))
 198         OutputFilename = IFN.drop_back(3);
 199       else if (IFN.endswith(".mir"))
 200         OutputFilename = IFN.drop_back(4);
 201       else
 202         OutputFilename = IFN;
 203
 204       switch (FileType) {
 205       case TargetMachine::CGFT_AssemblyFile:
 206         if (TargetName[0] == 'c') {
 207           if (TargetName[1] == 0)
 208             OutputFilename += ".cbe.c";
 209           else if (TargetName[1] == 'p' && TargetName[2] == 'p')
 210             OutputFilename += ".cpp";
 211           else
 212             OutputFilename += ".s";
 213         } else
 214           OutputFilename += ".s";
 215         break;
 216       case TargetMachine::CGFT_ObjectFile:
 217         if (OS == Triple::Win32)
 218           OutputFilename += ".obj";
 219         else
 220           OutputFilename += ".o";
 221         break;
 222       case TargetMachine::CGFT_Null:
 223         OutputFilename += ".null";
 224         break;
 225       }
 226     }
 227   }
 228
 229   // Decide if we need "binary" output.
 230   bool Binary = false;
 231   switch (FileType) {
 232   case TargetMachine::CGFT_AssemblyFile:
 233     break;
 234   case TargetMachine::CGFT_ObjectFile:
 235   case TargetMachine::CGFT_Null:
 236     Binary = true;
 237     break;
 238   }
 239
 240   // Open the file.
 241   std::error_code EC;
 242   sys::fs::OpenFlags OpenFlags = sys::fs::OF_None;
 243   if (!Binary)
 244     OpenFlags |= sys::fs::OF_Text;
 245   auto FDOut = std::make_unique<ToolOutputFile>(OutputFilename, EC, OpenFlags);
 246   if (EC) {
 247     WithColor::error() << EC.message() << '\n';
 248     return nullptr;
 249   }
 250
 251   return FDOut;
 252 }
 253
 254 struct LLCDiagnosticHandler : public DiagnosticHandler {
 255   bool *HasError;
 256   LLCDiagnosticHandler(bool *HasErrorPtr) : HasError(HasErrorPtr) {}
 257   bool handleDiagnostics(const DiagnosticInfo &DI) override {
 258     if (DI.getSeverity() == DS_Error)
 259       *HasError = true;
 260
 261     if (auto *Remark = dyn_cast<DiagnosticInfoOptimizationBase>(&DI))
 262       if (!Remark->isEnabled())
 263         return true;
 264
 265     DiagnosticPrinterRawOStream DP(errs());
 266     errs() << LLVMContext::getDiagnosticMessagePrefix(DI.getSeverity()) << ": ";
 267     DI.print(DP);
 268     errs() << "\n";
 269     return true;
 270   }
 271 };
 272
 273 static void InlineAsmDiagHandler(const SMDiagnostic &SMD, void *Context,
 274                                  unsigned LocCookie) {
 275   bool *HasError = static_cast<bool *>(Context);
 276   if (SMD.getKind() == SourceMgr::DK_Error)
 277     *HasError = true;
 278
 279   SMD.print(nullptr, errs());
 280
 281   // For testing purposes, we print the LocCookie here.
 282   if (LocCookie)
 283     WithColor::note() << "!srcloc = " << LocCookie << "\n";
 284 }
 285
 286 // main - Entry point for the llc compiler.
 287 //
 288 int main(int argc, char **argv) {
 289   InitLLVM X(argc, argv);
 290
 291   // Enable debug stream buffering.
 292   EnableDebugBuffering = true;
 293
 294   LLVMContext Context;
 295
 296   // Initialize targets first, so that --version shows registered targets.
 297   InitializeAllTargets();
 298   InitializeAllTargetMCs();
 299   InitializeAllAsmPrinters();
 300   InitializeAllAsmParsers();
 301
 302   // Initialize codegen and IR passes used by llc so that the -print-after,
 303   // -print-before, and -stop-after options work.
 304   PassRegistry *Registry = PassRegistry::getPassRegistry();
 305   initializeCore(*Registry);
 306   initializeCodeGen(*Registry);
 307   initializeLoopStrengthReducePass(*Registry);
 308   initializeLowerIntrinsicsPass(*Registry);
 309   initializeEntryExitInstrumenterPass(*Registry);
 310   initializePostInlineEntryExitInstrumenterPass(*Registry);
 311   initializeUnreachableBlockElimLegacyPassPass(*Registry);
 312   initializeConstantHoistingLegacyPassPass(*Registry);
 313   initializeScalarOpts(*Registry);
 314   initializeVectorization(*Registry);
 315   initializeScalarizeMaskedMemIntrinPass(*Registry);
 316   initializeExpandReductionsPass(*Registry);
 317   initializeHardwareLoopsPass(*Registry);
 318
 319   // Initialize debugging passes.
 320   initializeScavengerTestPass(*Registry);
 321
 322   // Register the target printer for --version.
 323   cl::AddExtraVersionPrinter(TargetRegistry::printRegisteredTargetsForVersion);
 324
 325   cl::ParseCommandLineOptions(argc, argv, "llvm system compiler\n");
 326
 327   Context.setDiscardValueNames(DiscardValueNames);
 328
 329   // Set a diagnostic handler that doesn't exit on the first error
 330   bool HasError = false;
 331   Context.setDiagnosticHandler(
 332       std::make_unique<LLCDiagnosticHandler>(&HasError));
 333   Context.setInlineAsmDiagnosticHandler(InlineAsmDiagHandler, &HasError);
 334
 335   Expected<std::unique_ptr<ToolOutputFile>> RemarksFileOrErr =
 336       setupOptimizationRemarks(Context, RemarksFilename, RemarksPasses,
 337                                RemarksFormat, RemarksWithHotness,
 338                                RemarksHotnessThreshold);
 339   if (Error E = RemarksFileOrErr.takeError()) {
 340     WithColor::error(errs(), argv[0]) << toString(std::move(E)) << '\n';
 341     return 1;
 342   }
 343   std::unique_ptr<ToolOutputFile> RemarksFile = std::move(*RemarksFileOrErr);
 344
 345   if (InputLanguage != "" && InputLanguage != "ir" &&
 346       InputLanguage != "mir") {
 347     WithColor::error(errs(), argv[0])
 348         << "input language must be '', 'IR' or 'MIR'\n";
 349     return 1;
 350   }
 351
 352   // Compile the module TimeCompilations times to give better compile time
 353   // metrics.
 354   for (unsigned I = TimeCompilations; I; --I)
 355     if (int RetVal = compileModule(argv, Context))
 356       return RetVal;
 357
 358   if (RemarksFile)
 359     RemarksFile->keep();
 360   return 0;
 361 }
 362
 363 static bool addPass(PassManagerBase &PM, const char *argv0,
 364                     StringRef PassName, TargetPassConfig &TPC) {
 365   if (PassName == "none")
 366     return false;
 367
 368   const PassRegistry *PR = PassRegistry::getPassRegistry();
 369   const PassInfo *PI = PR->getPassInfo(PassName);
 370   if (!PI) {
 371     WithColor::error(errs(), argv0)
 372         << "run-pass " << PassName << " is not registered.\n";
 373     return true;
 374   }
 375
 376   Pass *P;
 377   if (PI->getNormalCtor())
 378     P = PI->getNormalCtor()();
 379   else {
 380     WithColor::error(errs(), argv0)
 381         << "cannot create pass: " << PI->getPassName() << "\n";
 382     return true;
 383   }
 384   std::string Banner = std::string("After ") + std::string(P->getPassName());
 385   PM.add(P);
 386   TPC.printAndVerify(Banner);
 387
 388   return false;
 389 }
 390
 391 static int compileModule(char **argv, LLVMContext &Context) {
 392   // Load the module to be compiled...
 393   SMDiagnostic Err;
 394   std::unique_ptr<Module> M;
 395   std::unique_ptr<MIRParser> MIR;
 396   Triple TheTriple;
 397
 398   bool SkipModule = MCPU == "help" ||
 399                     (!MAttrs.empty() && MAttrs.front() == "help");
 400
 401   // If user just wants to list available options, skip module loading
 402   if (!SkipModule) {
 403     if (InputLanguage == "mir" ||
 404         (InputLanguage == "" && StringRef(InputFilename).endswith(".mir"))) {
 405       MIR = createMIRParserFromFile(InputFilename, Err, Context);
 406       if (MIR)
 407         M = MIR->parseIRModule();
 408     } else
 409       M = parseIRFile(InputFilename, Err, Context, false);
 410     if (!M) {
 411       Err.print(argv[0], WithColor::error(errs(), argv[0]));
 412       return 1;
 413     }
 414
 415     // If we are supposed to override the target triple, do so now.
 416     if (!TargetTriple.empty())
 417       M->setTargetTriple(Triple::normalize(TargetTriple));
 418     TheTriple = Triple(M->getTargetTriple());
 419   } else {
 420     TheTriple = Triple(Triple::normalize(TargetTriple));
 421   }
 422
 423   if (TheTriple.getTriple().empty())
 424     TheTriple.setTriple(sys::getDefaultTargetTriple());
 425
 426   // Get the target specific parser.
 427   std::string Error;
 428   const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
 429                                                          Error);
 430   if (!TheTarget) {
 431     WithColor::error(errs(), argv[0]) << Error;
 432     return 1;
 433   }
 434
 435   std::string CPUStr = getCPUStr(), FeaturesStr = getFeaturesStr();
 436
 437   CodeGenOpt::Level OLvl = CodeGenOpt::Default;
 438   switch (OptLevel) {
 439   default:
 440     WithColor::error(errs(), argv[0]) << "invalid optimization level.\n";
 441     return 1;
 442   case ' ': break;
 443   case '0': OLvl = CodeGenOpt::None; break;
 444   case '1': OLvl = CodeGenOpt::Less; break;
 445   case '2': OLvl = CodeGenOpt::Default; break;
 446   case '3': OLvl = CodeGenOpt::Aggressive; break;
 447   }
 448
 449   TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
 450   Options.DisableIntegratedAS = NoIntegratedAssembler;
 451   Options.MCOptions.ShowMCEncoding = ShowMCEncoding;
 452   Options.MCOptions.MCUseDwarfDirectory = EnableDwarfDirectory;
 453   Options.MCOptions.AsmVerbose = AsmVerbose;
 454   Options.MCOptions.PreserveAsmComments = PreserveComments;
 455   Options.MCOptions.IASSearchPaths = IncludeDirs;
 456   Options.MCOptions.SplitDwarfFile = SplitDwarfFile;
 457
 458   std::unique_ptr<TargetMachine> Target(TheTarget->createTargetMachine(
 459       TheTriple.getTriple(), CPUStr, FeaturesStr, Options, getRelocModel(),
 460       getCodeModel(), OLvl));
 461
 462   assert(Target && "Could not allocate target machine!");
 463
 464   // If we don't have a module then just exit now. We do this down
 465   // here since the CPU/Feature help is underneath the target machine
 466   // creation.
 467   if (SkipModule)
 468     return 0;
 469
 470   assert(M && "Should have exited if we didn't have a module!");
 471   if (FloatABIForCalls != FloatABI::Default)
 472     Options.FloatABIType = FloatABIForCalls;
 473
 474   // Figure out where we are going to send the output.
 475   std::unique_ptr<ToolOutputFile> Out =
 476       GetOutputStream(TheTarget->getName(), TheTriple.getOS(), argv[0]);
 477   if (!Out) return 1;
 478
 479   std::unique_ptr<ToolOutputFile> DwoOut;
 480   if (!SplitDwarfOutputFile.empty()) {
 481     std::error_code EC;
 482     DwoOut = std::make_unique<ToolOutputFile>(SplitDwarfOutputFile, EC,
 483                                                sys::fs::OF_None);
 484     if (EC) {
 485       WithColor::error(errs(), argv[0]) << EC.message() << '\n';
 486       return 1;
 487     }
 488   }
 489
 490   // Build up all of the passes that we want to do to the module.
 491   legacy::PassManager PM;
 492
 493   // Add an appropriate TargetLibraryInfo pass for the module's triple.
 494   TargetLibraryInfoImpl TLII(Triple(M->getTargetTriple()));
 495
 496   // The -disable-simplify-libcalls flag actually disables all builtin optzns.
 497   if (DisableSimplifyLibCalls)
 498     TLII.disableAllFunctions();
 499   PM.add(new TargetLibraryInfoWrapperPass(TLII));
 500
 501   // Add the target data from the target machine, if it exists, or the module.
 502   M->setDataLayout(Target->createDataLayout());
 503
 504   // This needs to be done after setting datalayout since it calls verifier
 505   // to check debug info whereas verifier relies on correct datalayout.
 506   UpgradeDebugInfo(*M);
 507
 508   // Verify module immediately to catch problems before doInitialization() is
 509   // called on any passes.
 510   if (!NoVerify && verifyModule(*M, &errs())) {
 511     std::string Prefix =
 512         (Twine(argv[0]) + Twine(": ") + Twine(InputFilename)).str();
 513     WithColor::error(errs(), Prefix) << "input module is broken!\n";
 514     return 1;
 515   }
 516
 517   // Override function attributes based on CPUStr, FeaturesStr, and command line
 518   // flags.
 519   setFunctionAttributes(CPUStr, FeaturesStr, *M);
 520
 521   if (RelaxAll.getNumOccurrences() > 0 &&
 522       FileType != TargetMachine::CGFT_ObjectFile)
 523     WithColor::warning(errs(), argv[0])
 524         << ": warning: ignoring -mc-relax-all because filetype != obj";
 525
 526   {
 527     raw_pwrite_stream *OS = &Out->os();
 528
 529     // Manually do the buffering rather than using buffer_ostream,
 530     // so we can memcmp the contents in CompileTwice mode
 531     SmallVector<char, 0> Buffer;
 532     std::unique_ptr<raw_svector_ostream> BOS;
 533     if ((FileType != TargetMachine::CGFT_AssemblyFile &&
 534          !Out->os().supportsSeeking()) ||
 535         CompileTwice) {
 536       BOS = std::make_unique<raw_svector_ostream>(Buffer);
 537       OS = BOS.get();
 538     }
 539
 540     const char *argv0 = argv[0];
 541     LLVMTargetMachine &LLVMTM = static_cast<LLVMTargetMachine &>(*Target);
 542     MachineModuleInfoWrapperPass *MMIWP =
 543         new MachineModuleInfoWrapperPass(&LLVMTM);
 544
 545     // Construct a custom pass pipeline that starts after instruction
 546     // selection.
 547     if (!RunPassNames->empty()) {
 548       if (!MIR) {
 549         WithColor::warning(errs(), argv[0])
 550             << "run-pass is for .mir file only.\n";
 551         return 1;
 552       }
 553       TargetPassConfig &TPC = *LLVMTM.createPassConfig(PM);
 554       if (TPC.hasLimitedCodeGenPipeline()) {
 555         WithColor::warning(errs(), argv[0])
 556             << "run-pass cannot be used with "
 557             << TPC.getLimitedCodeGenPipelineReason(" and ") << ".\n";
 558         return 1;
 559       }
 560
 561       TPC.setDisableVerify(NoVerify);
 562       PM.add(&TPC);
 563       PM.add(MMIWP);
 564       TPC.printAndVerify("");
 565       for (const std::string &RunPassName : *RunPassNames) {
 566         if (addPass(PM, argv0, RunPassName, TPC))
 567           return 1;
 568       }
 569       TPC.setInitialized();
 570       PM.add(createPrintMIRPass(*OS));
 571       PM.add(createFreeMachineFunctionPass());
 572     } else if (Target->addPassesToEmitFile(PM, *OS,
 573                                            DwoOut ? &DwoOut->os() : nullptr,
 574                                            FileType, NoVerify, MMIWP)) {
 575       WithColor::warning(errs(), argv[0])
 576           << "target does not support generation of this"
 577           << " file type!\n";
 578       return 1;
 579     }
 580
 581     if (MIR) {
 582       assert(MMIWP && "Forgot to create MMIWP?");
 583       if (MIR->parseMachineFunctions(*M, MMIWP->getMMI()))
 584         return 1;
 585     }
 586
 587     // Before executing passes, print the final values of the LLVM options.
 588     cl::PrintOptionValues();
 589
 590     // If requested, run the pass manager over the same module again,
 591     // to catch any bugs due to persistent state in the passes. Note that
 592     // opt has the same functionality, so it may be worth abstracting this out
 593     // in the future.
 594     SmallVector<char, 0> CompileTwiceBuffer;
 595     if (CompileTwice) {
 596       std::unique_ptr<Module> M2(llvm::CloneModule(*M));
 597       PM.run(*M2);
 598       CompileTwiceBuffer = Buffer;
 599       Buffer.clear();
 600     }
 601
 602     PM.run(*M);
 603
 604     auto HasError =
 605         ((const LLCDiagnosticHandler *)(Context.getDiagHandlerPtr()))->HasError;
 606     if (*HasError)
 607       return 1;
 608
 609     // Compare the two outputs and make sure they're the same
 610     if (CompileTwice) {
 611       if (Buffer.size() != CompileTwiceBuffer.size() ||
 612           (memcmp(Buffer.data(), CompileTwiceBuffer.data(), Buffer.size()) !=
 613            0)) {
 614         errs()
 615             << "Running the pass manager twice changed the output.\n"
 616                "Writing the result of the second run to the specified output\n"
 617                "To generate the one-run comparison binary, just run without\n"
 618                "the compile-twice option\n";
 619         Out->os() << Buffer;
 620         Out->keep();
 621         return 1;
 622       }
 623     }
 624
 625     if (BOS) {
 626       Out->os() << Buffer;
 627     }
 628   }
 629
 630   // Declare success.
 631   Out->keep();
 632   if (DwoOut)
 633     DwoOut->keep();
 634
 635   return 0;
 636 }