1//===- opt.cpp - The LLVM Modular Optimizer -------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Optimizations may be specified an arbitrary number of times on the command
11// line, They are run in the order specified.
12//
13//===----------------------------------------------------------------------===//
14
15#include "BreakpointPrinter.h"
16#include "NewPMDriver.h"
17#include "PassPrinters.h"
18#include "llvm/ADT/Triple.h"
19#include "llvm/Analysis/CallGraph.h"
20#include "llvm/Analysis/CallGraphSCCPass.h"
21#include "llvm/Analysis/LoopPass.h"
22#include "llvm/Analysis/RegionPass.h"
23#include "llvm/Analysis/TargetLibraryInfo.h"
24#include "llvm/Analysis/TargetTransformInfo.h"
25#include "llvm/Bitcode/BitcodeWriterPass.h"
26#include "llvm/CodeGen/CommandFlags.h"
27#include "llvm/IR/DataLayout.h"
28#include "llvm/IR/DebugInfo.h"
29#include "llvm/IR/IRPrintingPasses.h"
30#include "llvm/IR/LLVMContext.h"
31#include "llvm/IR/LegacyPassManager.h"
32#include "llvm/IR/LegacyPassNameParser.h"
33#include "llvm/IR/Module.h"
34#include "llvm/IR/Verifier.h"
35#include "llvm/IRReader/IRReader.h"
36#include "llvm/InitializePasses.h"
37#include "llvm/LinkAllIR.h"
38#include "llvm/LinkAllPasses.h"
39#include "llvm/MC/SubtargetFeature.h"
40#include "llvm/Support/Debug.h"
41#include "llvm/Support/FileSystem.h"
42#include "llvm/Support/Host.h"
43#include "llvm/Support/ManagedStatic.h"
44#include "llvm/Support/PluginLoader.h"
45#include "llvm/Support/PrettyStackTrace.h"
46#include "llvm/Support/Signals.h"
47#include "llvm/Support/SourceMgr.h"
48#include "llvm/Support/SystemUtils.h"
49#include "llvm/Support/TargetRegistry.h"
50#include "llvm/Support/TargetSelect.h"
51#include "llvm/Support/ToolOutputFile.h"
52#include "llvm/Target/TargetMachine.h"
53#include "llvm/Transforms/IPO/PassManagerBuilder.h"
54#include "llvm/Transforms/Utils/Cloning.h"
55#include <algorithm>
56#include <memory>
57using namespace llvm;
58using namespace opt_tool;
59
60// The OptimizationList is automatically populated with registered Passes by the
61// PassNameParser.
62//
63static cl::list<const PassInfo*, bool, PassNameParser>
64PassList(cl::desc("Optimizations available:"));
65
66// This flag specifies a textual description of the optimization pass pipeline
67// to run over the module. This flag switches opt to use the new pass manager
68// infrastructure, completely disabling all of the flags specific to the old
69// pass management.
70static cl::opt<std::string> PassPipeline(
71    "passes",
72    cl::desc("A textual description of the pass pipeline for optimizing"),
73    cl::Hidden);
74
75// Other command line options...
76//
77static cl::opt<std::string>
78InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
79    cl::init("-"), cl::value_desc("filename"));
80
81static cl::opt<std::string>
82OutputFilename("o", cl::desc("Override output filename"),
83               cl::value_desc("filename"));
84
85static cl::opt<bool>
86Force("f", cl::desc("Enable binary output on terminals"));
87
88static cl::opt<bool>
89PrintEachXForm("p", cl::desc("Print module after each transformation"));
90
91static cl::opt<bool>
92NoOutput("disable-output",
93         cl::desc("Do not write result bitcode file"), cl::Hidden);
94
95static cl::opt<bool>
96OutputAssembly("S", cl::desc("Write output as LLVM assembly"));
97
98static cl::opt<bool>
99NoVerify("disable-verify", cl::desc("Do not run the verifier"), cl::Hidden);
100
101static cl::opt<bool>
102VerifyEach("verify-each", cl::desc("Verify after each transform"));
103
104static cl::opt<bool>
105    DisableDITypeMap("disable-debug-info-type-map",
106                     cl::desc("Don't use a uniquing type map for debug info"));
107
108static cl::opt<bool>
109StripDebug("strip-debug",
110           cl::desc("Strip debugger symbol info from translation unit"));
111
112static cl::opt<bool>
113DisableInline("disable-inlining", cl::desc("Do not run the inliner pass"));
114
115static cl::opt<bool>
116DisableOptimizations("disable-opt",
117                     cl::desc("Do not run any optimization passes"));
118
119static cl::opt<bool>
120StandardLinkOpts("std-link-opts",
121                 cl::desc("Include the standard link time optimizations"));
122
123static cl::opt<bool>
124OptLevelO1("O1",
125           cl::desc("Optimization level 1. Similar to clang -O1"));
126
127static cl::opt<bool>
128OptLevelO2("O2",
129           cl::desc("Optimization level 2. Similar to clang -O2"));
130
131static cl::opt<bool>
132OptLevelOs("Os",
133           cl::desc("Like -O2 with extra optimizations for size. Similar to clang -Os"));
134
135static cl::opt<bool>
136OptLevelOz("Oz",
137           cl::desc("Like -Os but reduces code size further. Similar to clang -Oz"));
138
139static cl::opt<bool>
140OptLevelO3("O3",
141           cl::desc("Optimization level 3. Similar to clang -O3"));
142
143static cl::opt<unsigned>
144CodeGenOptLevel("codegen-opt-level",
145                cl::desc("Override optimization level for codegen hooks"));
146
147static cl::opt<std::string>
148TargetTriple("mtriple", cl::desc("Override target triple for module"));
149
150static cl::opt<bool>
151UnitAtATime("funit-at-a-time",
152            cl::desc("Enable IPO. This corresponds to gcc's -funit-at-a-time"),
153            cl::init(true));
154
155static cl::opt<bool>
156DisableLoopUnrolling("disable-loop-unrolling",
157                     cl::desc("Disable loop unrolling in all relevant passes"),
158                     cl::init(false));
159static cl::opt<bool>
160DisableLoopVectorization("disable-loop-vectorization",
161                     cl::desc("Disable the loop vectorization pass"),
162                     cl::init(false));
163
164static cl::opt<bool>
165DisableSLPVectorization("disable-slp-vectorization",
166                        cl::desc("Disable the slp vectorization pass"),
167                        cl::init(false));
168
169static cl::opt<bool> EmitSummaryIndex("module-summary",
170                                      cl::desc("Emit module summary index"),
171                                      cl::init(false));
172
173static cl::opt<bool> EmitModuleHash("module-hash", cl::desc("Emit module hash"),
174                                    cl::init(false));
175
176static cl::opt<bool>
177DisableSimplifyLibCalls("disable-simplify-libcalls",
178                        cl::desc("Disable simplify-libcalls"));
179
180static cl::opt<bool>
181Quiet("q", cl::desc("Obsolete option"), cl::Hidden);
182
183static cl::alias
184QuietA("quiet", cl::desc("Alias for -q"), cl::aliasopt(Quiet));
185
186static cl::opt<bool>
187AnalyzeOnly("analyze", cl::desc("Only perform analysis, no optimization"));
188
189static cl::opt<bool>
190PrintBreakpoints("print-breakpoints-for-testing",
191                 cl::desc("Print select breakpoints location for testing"));
192
193static cl::opt<std::string>
194DefaultDataLayout("default-data-layout",
195          cl::desc("data layout string to use if not specified by module"),
196          cl::value_desc("layout-string"), cl::init(""));
197
198static cl::opt<bool> PreserveBitcodeUseListOrder(
199    "preserve-bc-uselistorder",
200    cl::desc("Preserve use-list order when writing LLVM bitcode."),
201    cl::init(true), cl::Hidden);
202
203static cl::opt<bool> PreserveAssemblyUseListOrder(
204    "preserve-ll-uselistorder",
205    cl::desc("Preserve use-list order when writing LLVM assembly."),
206    cl::init(false), cl::Hidden);
207
208static cl::opt<bool>
209    RunTwice("run-twice",
210             cl::desc("Run all passes twice, re-using the same pass manager."),
211             cl::init(false), cl::Hidden);
212
213static cl::opt<bool> DiscardValueNames(
214    "discard-value-names",
215    cl::desc("Discard names from Value (other than GlobalValue)."),
216    cl::init(false), cl::Hidden);
217
218static inline void addPass(legacy::PassManagerBase &PM, Pass *P) {
219  // Add the pass to the pass manager...
220  PM.add(P);
221
222  // If we are verifying all of the intermediate steps, add the verifier...
223  if (VerifyEach)
224    PM.add(createVerifierPass());
225}
226
227/// This routine adds optimization passes based on selected optimization level,
228/// OptLevel.
229///
230/// OptLevel - Optimization Level
231static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
232                                  legacy::FunctionPassManager &FPM,
233                                  TargetMachine *TM, unsigned OptLevel,
234                                  unsigned SizeLevel) {
235  if (!NoVerify || VerifyEach)
236    FPM.add(createVerifierPass()); // Verify that input is correct
237
238  PassManagerBuilder Builder;
239  Builder.OptLevel = OptLevel;
240  Builder.SizeLevel = SizeLevel;
241
242  if (DisableInline) {
243    // No inlining pass
244  } else if (OptLevel > 1) {
245    Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel);
246  } else {
247    Builder.Inliner = createAlwaysInlinerPass();
248  }
249  Builder.DisableUnitAtATime = !UnitAtATime;
250  Builder.DisableUnrollLoops = (DisableLoopUnrolling.getNumOccurrences() > 0) ?
251                               DisableLoopUnrolling : OptLevel == 0;
252
253  // This is final, unless there is a #pragma vectorize enable
254  if (DisableLoopVectorization)
255    Builder.LoopVectorize = false;
256  // If option wasn't forced via cmd line (-vectorize-loops, -loop-vectorize)
257  else if (!Builder.LoopVectorize)
258    Builder.LoopVectorize = OptLevel > 1 && SizeLevel < 2;
259
260  // When #pragma vectorize is on for SLP, do the same as above
261  Builder.SLPVectorize =
262      DisableSLPVectorization ? false : OptLevel > 1 && SizeLevel < 2;
263
264  // Add target-specific passes that need to run as early as possible.
265  if (TM)
266    Builder.addExtension(
267        PassManagerBuilder::EP_EarlyAsPossible,
268        [&](const PassManagerBuilder &, legacy::PassManagerBase &PM) {
269          TM->addEarlyAsPossiblePasses(PM);
270        });
271
272  Builder.populateFunctionPassManager(FPM);
273  Builder.populateModulePassManager(MPM);
274}
275
276static void AddStandardLinkPasses(legacy::PassManagerBase &PM) {
277  PassManagerBuilder Builder;
278  Builder.VerifyInput = true;
279  if (DisableOptimizations)
280    Builder.OptLevel = 0;
281
282  if (!DisableInline)
283    Builder.Inliner = createFunctionInliningPass();
284  Builder.populateLTOPassManager(PM);
285}
286
287//===----------------------------------------------------------------------===//
288// CodeGen-related helper functions.
289//
290
291static CodeGenOpt::Level GetCodeGenOptLevel() {
292  if (CodeGenOptLevel.getNumOccurrences())
293    return static_cast<CodeGenOpt::Level>(unsigned(CodeGenOptLevel));
294  if (OptLevelO1)
295    return CodeGenOpt::Less;
296  if (OptLevelO2)
297    return CodeGenOpt::Default;
298  if (OptLevelO3)
299    return CodeGenOpt::Aggressive;
300  return CodeGenOpt::None;
301}
302
303// Returns the TargetMachine instance or zero if no triple is provided.
304static TargetMachine* GetTargetMachine(Triple TheTriple, StringRef CPUStr,
305                                       StringRef FeaturesStr,
306                                       const TargetOptions &Options) {
307  std::string Error;
308  const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
309                                                         Error);
310  // Some modules don't specify a triple, and this is okay.
311  if (!TheTarget) {
312    return nullptr;
313  }
314
315  return TheTarget->createTargetMachine(TheTriple.getTriple(), CPUStr,
316                                        FeaturesStr, Options, getRelocModel(),
317                                        CMModel, GetCodeGenOptLevel());
318}
319
320#ifdef LINK_POLLY_INTO_TOOLS
321namespace polly {
322void initializePollyPasses(llvm::PassRegistry &Registry);
323}
324#endif
325
326//===----------------------------------------------------------------------===//
327// main for opt
328//
329int main(int argc, char **argv) {
330  sys::PrintStackTraceOnErrorSignal(argv[0]);
331  llvm::PrettyStackTraceProgram X(argc, argv);
332
333  // Enable debug stream buffering.
334  EnableDebugBuffering = true;
335
336  llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
337  LLVMContext Context;
338
339  InitializeAllTargets();
340  InitializeAllTargetMCs();
341  InitializeAllAsmPrinters();
342
343  // Initialize passes
344  PassRegistry &Registry = *PassRegistry::getPassRegistry();
345  initializeCore(Registry);
346  initializeScalarOpts(Registry);
347  initializeObjCARCOpts(Registry);
348  initializeVectorization(Registry);
349  initializeIPO(Registry);
350  initializeAnalysis(Registry);
351  initializeTransformUtils(Registry);
352  initializeInstCombine(Registry);
353  initializeInstrumentation(Registry);
354  initializeTarget(Registry);
355  // For codegen passes, only passes that do IR to IR transformation are
356  // supported.
357  initializeCodeGenPreparePass(Registry);
358  initializeAtomicExpandPass(Registry);
359  initializeRewriteSymbolsPass(Registry);
360  initializeWinEHPreparePass(Registry);
361  initializeDwarfEHPreparePass(Registry);
362  initializeSafeStackPass(Registry);
363  initializeSjLjEHPreparePass(Registry);
364  initializePreISelIntrinsicLoweringLegacyPassPass(Registry);
365  initializeGlobalMergePass(Registry);
366  initializeInterleavedAccessPass(Registry);
367  initializeUnreachableBlockElimLegacyPassPass(Registry);
368
369#ifdef LINK_POLLY_INTO_TOOLS
370  polly::initializePollyPasses(Registry);
371#endif
372
373  cl::ParseCommandLineOptions(argc, argv,
374    "llvm .bc -> .bc modular optimizer and analysis printer\n");
375
376  if (AnalyzeOnly && NoOutput) {
377    errs() << argv[0] << ": analyze mode conflicts with no-output mode.\n";
378    return 1;
379  }
380
381  SMDiagnostic Err;
382
383  Context.setDiscardValueNames(DiscardValueNames);
384  if (!DisableDITypeMap)
385    Context.enableDebugTypeODRUniquing();
386
387  // Load the input module...
388  std::unique_ptr<Module> M = parseIRFile(InputFilename, Err, Context);
389
390  if (!M) {
391    Err.print(argv[0], errs());
392    return 1;
393  }
394
395  // Strip debug info before running the verifier.
396  if (StripDebug)
397    StripDebugInfo(*M);
398
399  // Immediately run the verifier to catch any problems before starting up the
400  // pass pipelines.  Otherwise we can crash on broken code during
401  // doInitialization().
402  if (!NoVerify && verifyModule(*M, &errs())) {
403    errs() << argv[0] << ": " << InputFilename
404           << ": error: input module is broken!\n";
405    return 1;
406  }
407
408  // If we are supposed to override the target triple, do so now.
409  if (!TargetTriple.empty())
410    M->setTargetTriple(Triple::normalize(TargetTriple));
411
412  // Figure out what stream we are supposed to write to...
413  std::unique_ptr<tool_output_file> Out;
414  if (NoOutput) {
415    if (!OutputFilename.empty())
416      errs() << "WARNING: The -o (output filename) option is ignored when\n"
417                "the --disable-output option is used.\n";
418  } else {
419    // Default to standard output.
420    if (OutputFilename.empty())
421      OutputFilename = "-";
422
423    std::error_code EC;
424    Out.reset(new tool_output_file(OutputFilename, EC, sys::fs::F_None));
425    if (EC) {
426      errs() << EC.message() << '\n';
427      return 1;
428    }
429  }
430
431  Triple ModuleTriple(M->getTargetTriple());
432  std::string CPUStr, FeaturesStr;
433  TargetMachine *Machine = nullptr;
434  const TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
435
436  if (ModuleTriple.getArch()) {
437    CPUStr = getCPUStr();
438    FeaturesStr = getFeaturesStr();
439    Machine = GetTargetMachine(ModuleTriple, CPUStr, FeaturesStr, Options);
440  }
441
442  std::unique_ptr<TargetMachine> TM(Machine);
443
444  // Override function attributes based on CPUStr, FeaturesStr, and command line
445  // flags.
446  setFunctionAttributes(CPUStr, FeaturesStr, *M);
447
448  // If the output is set to be emitted to standard out, and standard out is a
449  // console, print out a warning message and refuse to do it.  We don't
450  // impress anyone by spewing tons of binary goo to a terminal.
451  if (!Force && !NoOutput && !AnalyzeOnly && !OutputAssembly)
452    if (CheckBitcodeOutputToConsole(Out->os(), !Quiet))
453      NoOutput = true;
454
455  if (PassPipeline.getNumOccurrences() > 0) {
456    OutputKind OK = OK_NoOutput;
457    if (!NoOutput)
458      OK = OutputAssembly ? OK_OutputAssembly : OK_OutputBitcode;
459
460    VerifierKind VK = VK_VerifyInAndOut;
461    if (NoVerify)
462      VK = VK_NoVerifier;
463    else if (VerifyEach)
464      VK = VK_VerifyEachPass;
465
466    // The user has asked to use the new pass manager and provided a pipeline
467    // string. Hand off the rest of the functionality to the new code for that
468    // layer.
469    return runPassPipeline(argv[0], Context, *M, TM.get(), Out.get(),
470                           PassPipeline, OK, VK, PreserveAssemblyUseListOrder,
471                           PreserveBitcodeUseListOrder)
472               ? 0
473               : 1;
474  }
475
476  // Create a PassManager to hold and optimize the collection of passes we are
477  // about to build.
478  //
479  legacy::PassManager Passes;
480
481  // Add an appropriate TargetLibraryInfo pass for the module's triple.
482  TargetLibraryInfoImpl TLII(ModuleTriple);
483
484  // The -disable-simplify-libcalls flag actually disables all builtin optzns.
485  if (DisableSimplifyLibCalls)
486    TLII.disableAllFunctions();
487  Passes.add(new TargetLibraryInfoWrapperPass(TLII));
488
489  // Add an appropriate DataLayout instance for this module.
490  const DataLayout &DL = M->getDataLayout();
491  if (DL.isDefault() && !DefaultDataLayout.empty()) {
492    M->setDataLayout(DefaultDataLayout);
493  }
494
495  // Add internal analysis passes from the target machine.
496  Passes.add(createTargetTransformInfoWrapperPass(TM ? TM->getTargetIRAnalysis()
497                                                     : TargetIRAnalysis()));
498
499  std::unique_ptr<legacy::FunctionPassManager> FPasses;
500  if (OptLevelO1 || OptLevelO2 || OptLevelOs || OptLevelOz || OptLevelO3) {
501    FPasses.reset(new legacy::FunctionPassManager(M.get()));
502    FPasses->add(createTargetTransformInfoWrapperPass(
503        TM ? TM->getTargetIRAnalysis() : TargetIRAnalysis()));
504  }
505
506  if (PrintBreakpoints) {
507    // Default to standard output.
508    if (!Out) {
509      if (OutputFilename.empty())
510        OutputFilename = "-";
511
512      std::error_code EC;
513      Out = llvm::make_unique<tool_output_file>(OutputFilename, EC,
514                                                sys::fs::F_None);
515      if (EC) {
516        errs() << EC.message() << '\n';
517        return 1;
518      }
519    }
520    Passes.add(createBreakpointPrinter(Out->os()));
521    NoOutput = true;
522  }
523
524  // Create a new optimization pass for each one specified on the command line
525  for (unsigned i = 0; i < PassList.size(); ++i) {
526    if (StandardLinkOpts &&
527        StandardLinkOpts.getPosition() < PassList.getPosition(i)) {
528      AddStandardLinkPasses(Passes);
529      StandardLinkOpts = false;
530    }
531
532    if (OptLevelO1 && OptLevelO1.getPosition() < PassList.getPosition(i)) {
533      AddOptimizationPasses(Passes, *FPasses, TM.get(), 1, 0);
534      OptLevelO1 = false;
535    }
536
537    if (OptLevelO2 && OptLevelO2.getPosition() < PassList.getPosition(i)) {
538      AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 0);
539      OptLevelO2 = false;
540    }
541
542    if (OptLevelOs && OptLevelOs.getPosition() < PassList.getPosition(i)) {
543      AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 1);
544      OptLevelOs = false;
545    }
546
547    if (OptLevelOz && OptLevelOz.getPosition() < PassList.getPosition(i)) {
548      AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 2);
549      OptLevelOz = false;
550    }
551
552    if (OptLevelO3 && OptLevelO3.getPosition() < PassList.getPosition(i)) {
553      AddOptimizationPasses(Passes, *FPasses, TM.get(), 3, 0);
554      OptLevelO3 = false;
555    }
556
557    const PassInfo *PassInf = PassList[i];
558    Pass *P = nullptr;
559    if (PassInf->getTargetMachineCtor())
560      P = PassInf->getTargetMachineCtor()(TM.get());
561    else if (PassInf->getNormalCtor())
562      P = PassInf->getNormalCtor()();
563    else
564      errs() << argv[0] << ": cannot create pass: "
565             << PassInf->getPassName() << "\n";
566    if (P) {
567      PassKind Kind = P->getPassKind();
568      addPass(Passes, P);
569
570      if (AnalyzeOnly) {
571        switch (Kind) {
572        case PT_BasicBlock:
573          Passes.add(createBasicBlockPassPrinter(PassInf, Out->os(), Quiet));
574          break;
575        case PT_Region:
576          Passes.add(createRegionPassPrinter(PassInf, Out->os(), Quiet));
577          break;
578        case PT_Loop:
579          Passes.add(createLoopPassPrinter(PassInf, Out->os(), Quiet));
580          break;
581        case PT_Function:
582          Passes.add(createFunctionPassPrinter(PassInf, Out->os(), Quiet));
583          break;
584        case PT_CallGraphSCC:
585          Passes.add(createCallGraphPassPrinter(PassInf, Out->os(), Quiet));
586          break;
587        default:
588          Passes.add(createModulePassPrinter(PassInf, Out->os(), Quiet));
589          break;
590        }
591      }
592    }
593
594    if (PrintEachXForm)
595      Passes.add(
596          createPrintModulePass(errs(), "", PreserveAssemblyUseListOrder));
597  }
598
599  if (StandardLinkOpts) {
600    AddStandardLinkPasses(Passes);
601    StandardLinkOpts = false;
602  }
603
604  if (OptLevelO1)
605    AddOptimizationPasses(Passes, *FPasses, TM.get(), 1, 0);
606
607  if (OptLevelO2)
608    AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 0);
609
610  if (OptLevelOs)
611    AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 1);
612
613  if (OptLevelOz)
614    AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 2);
615
616  if (OptLevelO3)
617    AddOptimizationPasses(Passes, *FPasses, TM.get(), 3, 0);
618
619  if (FPasses) {
620    FPasses->doInitialization();
621    for (Function &F : *M)
622      FPasses->run(F);
623    FPasses->doFinalization();
624  }
625
626  // Check that the module is well formed on completion of optimization
627  if (!NoVerify && !VerifyEach)
628    Passes.add(createVerifierPass());
629
630  // In run twice mode, we want to make sure the output is bit-by-bit
631  // equivalent if we run the pass manager again, so setup two buffers and
632  // a stream to write to them. Note that llc does something similar and it
633  // may be worth to abstract this out in the future.
634  SmallVector<char, 0> Buffer;
635  SmallVector<char, 0> CompileTwiceBuffer;
636  std::unique_ptr<raw_svector_ostream> BOS;
637  raw_ostream *OS = nullptr;
638
639  // Write bitcode or assembly to the output as the last step...
640  if (!NoOutput && !AnalyzeOnly) {
641    assert(Out);
642    OS = &Out->os();
643    if (RunTwice) {
644      BOS = make_unique<raw_svector_ostream>(Buffer);
645      OS = BOS.get();
646    }
647    if (OutputAssembly) {
648      if (EmitSummaryIndex)
649        report_fatal_error("Text output is incompatible with -module-summary");
650      if (EmitModuleHash)
651        report_fatal_error("Text output is incompatible with -module-hash");
652      Passes.add(createPrintModulePass(*OS, "", PreserveAssemblyUseListOrder));
653    } else
654      Passes.add(createBitcodeWriterPass(*OS, PreserveBitcodeUseListOrder,
655                                         EmitSummaryIndex, EmitModuleHash));
656  }
657
658  // Before executing passes, print the final values of the LLVM options.
659  cl::PrintOptionValues();
660
661  // If requested, run all passes again with the same pass manager to catch
662  // bugs caused by persistent state in the passes
663  if (RunTwice) {
664      std::unique_ptr<Module> M2(CloneModule(M.get()));
665      Passes.run(*M2);
666      CompileTwiceBuffer = Buffer;
667      Buffer.clear();
668  }
669
670  // Now that we have all of the passes ready, run them.
671  Passes.run(*M);
672
673  // Compare the two outputs and make sure they're the same
674  if (RunTwice) {
675    assert(Out);
676    if (Buffer.size() != CompileTwiceBuffer.size() ||
677        (memcmp(Buffer.data(), CompileTwiceBuffer.data(), Buffer.size()) !=
678         0)) {
679      errs() << "Running the pass manager twice changed the output.\n"
680                "Writing the result of the second run to the specified output.\n"
681                "To generate the one-run comparison binary, just run without\n"
682                "the compile-twice option\n";
683      Out->os() << BOS->str();
684      Out->keep();
685      return 1;
686    }
687    Out->os() << BOS->str();
688  }
689
690  // Declare success.
691  if (!NoOutput || PrintBreakpoints)
692    Out->keep();
693
694  return 0;
695}
696