1//===--- BackendUtil.cpp - LLVM Backend Utilities -------------------------===//
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#include "clang/CodeGen/BackendUtil.h"
11#include "clang/Basic/Diagnostic.h"
12#include "clang/Basic/LangOptions.h"
13#include "clang/Basic/TargetOptions.h"
14#include "clang/Frontend/CodeGenOptions.h"
15#include "clang/Frontend/FrontendDiagnostic.h"
16#include "clang/Frontend/Utils.h"
17#include "llvm/ADT/StringSwitch.h"
18#include "llvm/Bitcode/BitcodeWriterPass.h"
19#include "llvm/CodeGen/RegAllocRegistry.h"
20#include "llvm/CodeGen/SchedulerRegistry.h"
21#include "llvm/IR/DataLayout.h"
22#include "llvm/IR/IRPrintingPasses.h"
23#include "llvm/IR/Module.h"
24#include "llvm/IR/Verifier.h"
25#include "llvm/MC/SubtargetFeature.h"
26#include "llvm/PassManager.h"
27#include "llvm/Support/CommandLine.h"
28#include "llvm/Support/FormattedStream.h"
29#include "llvm/Support/PrettyStackTrace.h"
30#include "llvm/Support/TargetRegistry.h"
31#include "llvm/Support/Timer.h"
32#include "llvm/Support/raw_ostream.h"
33#include "llvm/Target/TargetLibraryInfo.h"
34#include "llvm/Target/TargetMachine.h"
35#include "llvm/Target/TargetOptions.h"
36#include "llvm/Transforms/IPO.h"
37#include "llvm/Transforms/IPO/PassManagerBuilder.h"
38#include "llvm/Transforms/Instrumentation.h"
39#include "llvm/Transforms/ObjCARC.h"
40#include "llvm/Transforms/Scalar.h"
41#include <memory>
42using namespace clang;
43using namespace llvm;
44
45namespace {
46
47class EmitAssemblyHelper {
48  DiagnosticsEngine &Diags;
49  const CodeGenOptions &CodeGenOpts;
50  const clang::TargetOptions &TargetOpts;
51  const LangOptions &LangOpts;
52  Module *TheModule;
53
54  Timer CodeGenerationTime;
55
56  mutable PassManager *CodeGenPasses;
57  mutable PassManager *PerModulePasses;
58  mutable FunctionPassManager *PerFunctionPasses;
59
60private:
61  PassManager *getCodeGenPasses() const {
62    if (!CodeGenPasses) {
63      CodeGenPasses = new PassManager();
64      CodeGenPasses->add(new DataLayoutPass(TheModule));
65      if (TM)
66        TM->addAnalysisPasses(*CodeGenPasses);
67    }
68    return CodeGenPasses;
69  }
70
71  PassManager *getPerModulePasses() const {
72    if (!PerModulePasses) {
73      PerModulePasses = new PassManager();
74      PerModulePasses->add(new DataLayoutPass(TheModule));
75      if (TM)
76        TM->addAnalysisPasses(*PerModulePasses);
77    }
78    return PerModulePasses;
79  }
80
81  FunctionPassManager *getPerFunctionPasses() const {
82    if (!PerFunctionPasses) {
83      PerFunctionPasses = new FunctionPassManager(TheModule);
84      PerFunctionPasses->add(new DataLayoutPass(TheModule));
85      if (TM)
86        TM->addAnalysisPasses(*PerFunctionPasses);
87    }
88    return PerFunctionPasses;
89  }
90
91  void CreatePasses();
92
93  /// CreateTargetMachine - Generates the TargetMachine.
94  /// Returns Null if it is unable to create the target machine.
95  /// Some of our clang tests specify triples which are not built
96  /// into clang. This is okay because these tests check the generated
97  /// IR, and they require DataLayout which depends on the triple.
98  /// In this case, we allow this method to fail and not report an error.
99  /// When MustCreateTM is used, we print an error if we are unable to load
100  /// the requested target.
101  TargetMachine *CreateTargetMachine(bool MustCreateTM);
102
103  /// AddEmitPasses - Add passes necessary to emit assembly or LLVM IR.
104  ///
105  /// \return True on success.
106  bool AddEmitPasses(BackendAction Action, formatted_raw_ostream &OS);
107
108public:
109  EmitAssemblyHelper(DiagnosticsEngine &_Diags,
110                     const CodeGenOptions &CGOpts,
111                     const clang::TargetOptions &TOpts,
112                     const LangOptions &LOpts,
113                     Module *M)
114    : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts), LangOpts(LOpts),
115      TheModule(M), CodeGenerationTime("Code Generation Time"),
116      CodeGenPasses(nullptr), PerModulePasses(nullptr),
117      PerFunctionPasses(nullptr) {}
118
119  ~EmitAssemblyHelper() {
120    delete CodeGenPasses;
121    delete PerModulePasses;
122    delete PerFunctionPasses;
123    if (CodeGenOpts.DisableFree)
124      BuryPointer(TM.release());
125  }
126
127  std::unique_ptr<TargetMachine> TM;
128
129  void EmitAssembly(BackendAction Action, raw_ostream *OS);
130};
131
132// We need this wrapper to access LangOpts and CGOpts from extension functions
133// that we add to the PassManagerBuilder.
134class PassManagerBuilderWrapper : public PassManagerBuilder {
135public:
136  PassManagerBuilderWrapper(const CodeGenOptions &CGOpts,
137                            const LangOptions &LangOpts)
138      : PassManagerBuilder(), CGOpts(CGOpts), LangOpts(LangOpts) {}
139  const CodeGenOptions &getCGOpts() const { return CGOpts; }
140  const LangOptions &getLangOpts() const { return LangOpts; }
141private:
142  const CodeGenOptions &CGOpts;
143  const LangOptions &LangOpts;
144};
145
146}
147
148static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
149  if (Builder.OptLevel > 0)
150    PM.add(createObjCARCAPElimPass());
151}
152
153static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
154  if (Builder.OptLevel > 0)
155    PM.add(createObjCARCExpandPass());
156}
157
158static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
159  if (Builder.OptLevel > 0)
160    PM.add(createObjCARCOptPass());
161}
162
163static void addSampleProfileLoaderPass(const PassManagerBuilder &Builder,
164                                       PassManagerBase &PM) {
165  const PassManagerBuilderWrapper &BuilderWrapper =
166      static_cast<const PassManagerBuilderWrapper &>(Builder);
167  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
168  PM.add(createSampleProfileLoaderPass(CGOpts.SampleProfileFile));
169}
170
171static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
172                                     PassManagerBase &PM) {
173  PM.add(createAddDiscriminatorsPass());
174}
175
176static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
177                                    PassManagerBase &PM) {
178  PM.add(createBoundsCheckingPass());
179}
180
181static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
182                                      PassManagerBase &PM) {
183  PM.add(createAddressSanitizerFunctionPass());
184  PM.add(createAddressSanitizerModulePass());
185}
186
187static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
188                                   PassManagerBase &PM) {
189  const PassManagerBuilderWrapper &BuilderWrapper =
190      static_cast<const PassManagerBuilderWrapper&>(Builder);
191  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
192  PM.add(createMemorySanitizerPass(CGOpts.SanitizeMemoryTrackOrigins));
193
194  // MemorySanitizer inserts complex instrumentation that mostly follows
195  // the logic of the original code, but operates on "shadow" values.
196  // It can benefit from re-running some general purpose optimization passes.
197  if (Builder.OptLevel > 0) {
198    PM.add(createEarlyCSEPass());
199    PM.add(createReassociatePass());
200    PM.add(createLICMPass());
201    PM.add(createGVNPass());
202    PM.add(createInstructionCombiningPass());
203    PM.add(createDeadStoreEliminationPass());
204  }
205}
206
207static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
208                                   PassManagerBase &PM) {
209  PM.add(createThreadSanitizerPass());
210}
211
212static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
213                                     PassManagerBase &PM) {
214  const PassManagerBuilderWrapper &BuilderWrapper =
215      static_cast<const PassManagerBuilderWrapper&>(Builder);
216  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
217  PM.add(createDataFlowSanitizerPass(CGOpts.SanitizerBlacklistFile));
218}
219
220void EmitAssemblyHelper::CreatePasses() {
221  unsigned OptLevel = CodeGenOpts.OptimizationLevel;
222  CodeGenOptions::InliningMethod Inlining = CodeGenOpts.getInlining();
223
224  // Handle disabling of LLVM optimization, where we want to preserve the
225  // internal module before any optimization.
226  if (CodeGenOpts.DisableLLVMOpts) {
227    OptLevel = 0;
228    Inlining = CodeGenOpts.NoInlining;
229  }
230
231  PassManagerBuilderWrapper PMBuilder(CodeGenOpts, LangOpts);
232  PMBuilder.OptLevel = OptLevel;
233  PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
234  PMBuilder.BBVectorize = CodeGenOpts.VectorizeBB;
235  PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
236  PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
237
238  PMBuilder.DisableTailCalls = CodeGenOpts.DisableTailCalls;
239  PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
240  PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
241  PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
242
243  PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
244                         addAddDiscriminatorsPass);
245
246  if (!CodeGenOpts.SampleProfileFile.empty())
247    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
248                           addSampleProfileLoaderPass);
249
250  // In ObjC ARC mode, add the main ARC optimization passes.
251  if (LangOpts.ObjCAutoRefCount) {
252    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
253                           addObjCARCExpandPass);
254    PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
255                           addObjCARCAPElimPass);
256    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
257                           addObjCARCOptPass);
258  }
259
260  if (LangOpts.Sanitize.LocalBounds) {
261    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
262                           addBoundsCheckingPass);
263    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
264                           addBoundsCheckingPass);
265  }
266
267  if (LangOpts.Sanitize.Address) {
268    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
269                           addAddressSanitizerPasses);
270    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
271                           addAddressSanitizerPasses);
272  }
273
274  if (LangOpts.Sanitize.Memory) {
275    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
276                           addMemorySanitizerPass);
277    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
278                           addMemorySanitizerPass);
279  }
280
281  if (LangOpts.Sanitize.Thread) {
282    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
283                           addThreadSanitizerPass);
284    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
285                           addThreadSanitizerPass);
286  }
287
288  if (LangOpts.Sanitize.DataFlow) {
289    PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
290                           addDataFlowSanitizerPass);
291    PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
292                           addDataFlowSanitizerPass);
293  }
294
295  // Figure out TargetLibraryInfo.
296  Triple TargetTriple(TheModule->getTargetTriple());
297  PMBuilder.LibraryInfo = new TargetLibraryInfo(TargetTriple);
298  if (!CodeGenOpts.SimplifyLibCalls)
299    PMBuilder.LibraryInfo->disableAllFunctions();
300
301  switch (Inlining) {
302  case CodeGenOptions::NoInlining: break;
303  case CodeGenOptions::NormalInlining: {
304    PMBuilder.Inliner =
305        createFunctionInliningPass(OptLevel, CodeGenOpts.OptimizeSize);
306    break;
307  }
308  case CodeGenOptions::OnlyAlwaysInlining:
309    // Respect always_inline.
310    if (OptLevel == 0)
311      // Do not insert lifetime intrinsics at -O0.
312      PMBuilder.Inliner = createAlwaysInlinerPass(false);
313    else
314      PMBuilder.Inliner = createAlwaysInlinerPass();
315    break;
316  }
317
318  // Set up the per-function pass manager.
319  FunctionPassManager *FPM = getPerFunctionPasses();
320  if (CodeGenOpts.VerifyModule)
321    FPM->add(createVerifierPass());
322  PMBuilder.populateFunctionPassManager(*FPM);
323
324  // Set up the per-module pass manager.
325  PassManager *MPM = getPerModulePasses();
326  if (CodeGenOpts.VerifyModule)
327    MPM->add(createDebugInfoVerifierPass());
328
329  if (!CodeGenOpts.DisableGCov &&
330      (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes)) {
331    // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
332    // LLVM's -default-gcov-version flag is set to something invalid.
333    GCOVOptions Options;
334    Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
335    Options.EmitData = CodeGenOpts.EmitGcovArcs;
336    memcpy(Options.Version, CodeGenOpts.CoverageVersion, 4);
337    Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
338    Options.NoRedZone = CodeGenOpts.DisableRedZone;
339    Options.FunctionNamesInData =
340        !CodeGenOpts.CoverageNoFunctionNamesInData;
341    MPM->add(createGCOVProfilerPass(Options));
342    if (CodeGenOpts.getDebugInfo() == CodeGenOptions::NoDebugInfo)
343      MPM->add(createStripSymbolsPass(true));
344  }
345
346  PMBuilder.populateModulePassManager(*MPM);
347}
348
349TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
350  // Create the TargetMachine for generating code.
351  std::string Error;
352  std::string Triple = TheModule->getTargetTriple();
353  const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
354  if (!TheTarget) {
355    if (MustCreateTM)
356      Diags.Report(diag::err_fe_unable_to_create_target) << Error;
357    return nullptr;
358  }
359
360  unsigned CodeModel =
361    llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
362      .Case("small", llvm::CodeModel::Small)
363      .Case("kernel", llvm::CodeModel::Kernel)
364      .Case("medium", llvm::CodeModel::Medium)
365      .Case("large", llvm::CodeModel::Large)
366      .Case("default", llvm::CodeModel::Default)
367      .Default(~0u);
368  assert(CodeModel != ~0u && "invalid code model!");
369  llvm::CodeModel::Model CM = static_cast<llvm::CodeModel::Model>(CodeModel);
370
371  SmallVector<const char *, 16> BackendArgs;
372  BackendArgs.push_back("clang"); // Fake program name.
373  if (!CodeGenOpts.DebugPass.empty()) {
374    BackendArgs.push_back("-debug-pass");
375    BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
376  }
377  if (!CodeGenOpts.LimitFloatPrecision.empty()) {
378    BackendArgs.push_back("-limit-float-precision");
379    BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
380  }
381  if (llvm::TimePassesIsEnabled)
382    BackendArgs.push_back("-time-passes");
383  for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
384    BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
385  if (CodeGenOpts.NoGlobalMerge)
386    BackendArgs.push_back("-global-merge=false");
387  BackendArgs.push_back(nullptr);
388  llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
389                                    BackendArgs.data());
390
391  std::string FeaturesStr;
392  if (TargetOpts.Features.size()) {
393    SubtargetFeatures Features;
394    for (std::vector<std::string>::const_iterator
395           it = TargetOpts.Features.begin(),
396           ie = TargetOpts.Features.end(); it != ie; ++it)
397      Features.AddFeature(*it);
398    FeaturesStr = Features.getString();
399  }
400
401  llvm::Reloc::Model RM = llvm::Reloc::Default;
402  if (CodeGenOpts.RelocationModel == "static") {
403    RM = llvm::Reloc::Static;
404  } else if (CodeGenOpts.RelocationModel == "pic") {
405    RM = llvm::Reloc::PIC_;
406  } else {
407    assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
408           "Invalid PIC model!");
409    RM = llvm::Reloc::DynamicNoPIC;
410  }
411
412  CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
413  switch (CodeGenOpts.OptimizationLevel) {
414  default: break;
415  case 0: OptLevel = CodeGenOpt::None; break;
416  case 3: OptLevel = CodeGenOpt::Aggressive; break;
417  }
418
419  llvm::TargetOptions Options;
420
421  if (CodeGenOpts.DisableIntegratedAS)
422    Options.DisableIntegratedAS = true;
423
424  if (CodeGenOpts.CompressDebugSections)
425    Options.CompressDebugSections = true;
426
427  // Set frame pointer elimination mode.
428  if (!CodeGenOpts.DisableFPElim) {
429    Options.NoFramePointerElim = false;
430  } else if (CodeGenOpts.OmitLeafFramePointer) {
431    Options.NoFramePointerElim = false;
432  } else {
433    Options.NoFramePointerElim = true;
434  }
435
436  if (CodeGenOpts.UseInitArray)
437    Options.UseInitArray = true;
438
439  // Set float ABI type.
440  if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
441    Options.FloatABIType = llvm::FloatABI::Soft;
442  else if (CodeGenOpts.FloatABI == "hard")
443    Options.FloatABIType = llvm::FloatABI::Hard;
444  else {
445    assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
446    Options.FloatABIType = llvm::FloatABI::Default;
447  }
448
449  // Set FP fusion mode.
450  switch (CodeGenOpts.getFPContractMode()) {
451  case CodeGenOptions::FPC_Off:
452    Options.AllowFPOpFusion = llvm::FPOpFusion::Strict;
453    break;
454  case CodeGenOptions::FPC_On:
455    Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
456    break;
457  case CodeGenOptions::FPC_Fast:
458    Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
459    break;
460  }
461
462  Options.LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
463  Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
464  Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
465  Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
466  Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
467  Options.UseSoftFloat = CodeGenOpts.SoftFloat;
468  Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
469  Options.DisableTailCalls = CodeGenOpts.DisableTailCalls;
470  Options.TrapFuncName = CodeGenOpts.TrapFuncName;
471  Options.PositionIndependentExecutable = LangOpts.PIELevel != 0;
472  Options.FunctionSections = CodeGenOpts.FunctionSections;
473  Options.DataSections = CodeGenOpts.DataSections;
474
475  Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
476  Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
477  Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
478  Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
479  Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
480
481  TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
482                                                     FeaturesStr, Options,
483                                                     RM, CM, OptLevel);
484
485  return TM;
486}
487
488bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
489                                       formatted_raw_ostream &OS) {
490
491  // Create the code generator passes.
492  PassManager *PM = getCodeGenPasses();
493
494  // Add LibraryInfo.
495  llvm::Triple TargetTriple(TheModule->getTargetTriple());
496  TargetLibraryInfo *TLI = new TargetLibraryInfo(TargetTriple);
497  if (!CodeGenOpts.SimplifyLibCalls)
498    TLI->disableAllFunctions();
499  PM->add(TLI);
500
501  // Add Target specific analysis passes.
502  TM->addAnalysisPasses(*PM);
503
504  // Normal mode, emit a .s or .o file by running the code generator. Note,
505  // this also adds codegenerator level optimization passes.
506  TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
507  if (Action == Backend_EmitObj)
508    CGFT = TargetMachine::CGFT_ObjectFile;
509  else if (Action == Backend_EmitMCNull)
510    CGFT = TargetMachine::CGFT_Null;
511  else
512    assert(Action == Backend_EmitAssembly && "Invalid action!");
513
514  // Add ObjC ARC final-cleanup optimizations. This is done as part of the
515  // "codegen" passes so that it isn't run multiple times when there is
516  // inlining happening.
517  if (LangOpts.ObjCAutoRefCount &&
518      CodeGenOpts.OptimizationLevel > 0)
519    PM->add(createObjCARCContractPass());
520
521  if (TM->addPassesToEmitFile(*PM, OS, CGFT,
522                              /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
523    Diags.Report(diag::err_fe_unable_to_interface_with_target);
524    return false;
525  }
526
527  return true;
528}
529
530void EmitAssemblyHelper::EmitAssembly(BackendAction Action, raw_ostream *OS) {
531  TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : nullptr);
532  llvm::formatted_raw_ostream FormattedOS;
533
534  bool UsesCodeGen = (Action != Backend_EmitNothing &&
535                      Action != Backend_EmitBC &&
536                      Action != Backend_EmitLL);
537  if (!TM)
538    TM.reset(CreateTargetMachine(UsesCodeGen));
539
540  if (UsesCodeGen && !TM) return;
541  CreatePasses();
542
543  switch (Action) {
544  case Backend_EmitNothing:
545    break;
546
547  case Backend_EmitBC:
548    getPerModulePasses()->add(createBitcodeWriterPass(*OS));
549    break;
550
551  case Backend_EmitLL:
552    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
553    getPerModulePasses()->add(createPrintModulePass(FormattedOS));
554    break;
555
556  default:
557    FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
558    if (!AddEmitPasses(Action, FormattedOS))
559      return;
560  }
561
562  // Before executing passes, print the final values of the LLVM options.
563  cl::PrintOptionValues();
564
565  // Run passes. For now we do all passes at once, but eventually we
566  // would like to have the option of streaming code generation.
567
568  if (PerFunctionPasses) {
569    PrettyStackTraceString CrashInfo("Per-function optimization");
570
571    PerFunctionPasses->doInitialization();
572    for (Module::iterator I = TheModule->begin(),
573           E = TheModule->end(); I != E; ++I)
574      if (!I->isDeclaration())
575        PerFunctionPasses->run(*I);
576    PerFunctionPasses->doFinalization();
577  }
578
579  if (PerModulePasses) {
580    PrettyStackTraceString CrashInfo("Per-module optimization passes");
581    PerModulePasses->run(*TheModule);
582  }
583
584  if (CodeGenPasses) {
585    PrettyStackTraceString CrashInfo("Code generation");
586    CodeGenPasses->run(*TheModule);
587  }
588}
589
590void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
591                              const CodeGenOptions &CGOpts,
592                              const clang::TargetOptions &TOpts,
593                              const LangOptions &LOpts, StringRef TDesc,
594                              Module *M, BackendAction Action,
595                              raw_ostream *OS) {
596  EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
597
598  AsmHelper.EmitAssembly(Action, OS);
599
600  // If an optional clang TargetInfo description string was passed in, use it to
601  // verify the LLVM TargetMachine's DataLayout.
602  if (AsmHelper.TM && !TDesc.empty()) {
603    std::string DLDesc =
604        AsmHelper.TM->getDataLayout()->getStringRepresentation();
605    if (DLDesc != TDesc) {
606      unsigned DiagID = Diags.getCustomDiagID(
607          DiagnosticsEngine::Error, "backend data layout '%0' does not match "
608                                    "expected target description '%1'");
609      Diags.Report(DiagID) << DLDesc << TDesc;
610    }
611  }
612}
613