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 "llvm/Analysis/Verifier.h"
17 #include "llvm/Assembly/PrintModulePass.h"
18 #include "llvm/Bitcode/ReaderWriter.h"
19 #include "llvm/CodeGen/RegAllocRegistry.h"
20 #include "llvm/CodeGen/SchedulerRegistry.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/Module.h"
23 #include "llvm/MC/SubtargetFeature.h"
24 #include "llvm/PassManager.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/Support/FormattedStream.h"
27 #include "llvm/Support/PrettyStackTrace.h"
28 #include "llvm/Support/TargetRegistry.h"
29 #include "llvm/Support/Timer.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/Target/TargetLibraryInfo.h"
32 #include "llvm/Target/TargetMachine.h"
33 #include "llvm/Target/TargetOptions.h"
34 #include "llvm/TargetTransformInfo.h"
35 #include "llvm/Transforms/IPO.h"
36 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
37 #include "llvm/Transforms/Instrumentation.h"
38 #include "llvm/Transforms/Scalar.h"
39 using namespace clang;
40 using namespace llvm;
41 
42 namespace {
43 
44 class EmitAssemblyHelper {
45   DiagnosticsEngine &Diags;
46   const CodeGenOptions &CodeGenOpts;
47   const clang::TargetOptions &TargetOpts;
48   const LangOptions &LangOpts;
49   Module *TheModule;
50 
51   Timer CodeGenerationTime;
52 
53   mutable PassManager *CodeGenPasses;
54   mutable PassManager *PerModulePasses;
55   mutable FunctionPassManager *PerFunctionPasses;
56 
57 private:
58   PassManager *getCodeGenPasses(TargetMachine *TM) const {
59     if (!CodeGenPasses) {
60       CodeGenPasses = new PassManager();
61       CodeGenPasses->add(new DataLayout(TheModule));
62       // Add TargetTransformInfo.
63       if (TM) {
64         TargetTransformInfo *TTI =
65         new TargetTransformInfo(TM->getScalarTargetTransformInfo(),
66                                 TM->getVectorTargetTransformInfo());
67         CodeGenPasses->add(TTI);
68       }
69     }
70     return CodeGenPasses;
71   }
72 
73   PassManager *getPerModulePasses(TargetMachine *TM) const {
74     if (!PerModulePasses) {
75       PerModulePasses = new PassManager();
76       PerModulePasses->add(new DataLayout(TheModule));
77       if (TM) {
78         TargetTransformInfo *TTI =
79         new TargetTransformInfo(TM->getScalarTargetTransformInfo(),
80                                 TM->getVectorTargetTransformInfo());
81         PerModulePasses->add(TTI);
82       }
83     }
84     return PerModulePasses;
85   }
86 
87   FunctionPassManager *getPerFunctionPasses(TargetMachine *TM) const {
88     if (!PerFunctionPasses) {
89       PerFunctionPasses = new FunctionPassManager(TheModule);
90       PerFunctionPasses->add(new DataLayout(TheModule));
91       if (TM) {
92         TargetTransformInfo *TTI =
93         new TargetTransformInfo(TM->getScalarTargetTransformInfo(),
94                                 TM->getVectorTargetTransformInfo());
95         PerFunctionPasses->add(TTI);
96       }
97     }
98     return PerFunctionPasses;
99   }
100 
101 
102   void CreatePasses(TargetMachine *TM);
103 
104   /// CreateTargetMachine - Generates the TargetMachine.
105   /// Returns Null if it is unable to create the target machine.
106   /// Some of our clang tests specify triples which are not built
107   /// into clang. This is okay because these tests check the generated
108   /// IR, and they require DataLayout which depends on the triple.
109   /// In this case, we allow this method to fail and not report an error.
110   /// When MustCreateTM is used, we print an error if we are unable to load
111   /// the requested target.
112   TargetMachine *CreateTargetMachine(bool MustCreateTM);
113 
114   /// AddEmitPasses - Add passes necessary to emit assembly or LLVM IR.
115   ///
116   /// \return True on success.
117   bool AddEmitPasses(BackendAction Action, formatted_raw_ostream &OS,
118                      TargetMachine *TM);
119 
120 public:
121   EmitAssemblyHelper(DiagnosticsEngine &_Diags,
122                      const CodeGenOptions &CGOpts,
123                      const clang::TargetOptions &TOpts,
124                      const LangOptions &LOpts,
125                      Module *M)
126     : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts), LangOpts(LOpts),
127       TheModule(M), CodeGenerationTime("Code Generation Time"),
128       CodeGenPasses(0), PerModulePasses(0), PerFunctionPasses(0) {}
129 
130   ~EmitAssemblyHelper() {
131     delete CodeGenPasses;
132     delete PerModulePasses;
133     delete PerFunctionPasses;
134   }
135 
136   void EmitAssembly(BackendAction Action, raw_ostream *OS);
137 };
138 
139 // We need this wrapper to access LangOpts and CGOpts from extension functions
140 // that we add to the PassManagerBuilder.
141 class PassManagerBuilderWrapper : public PassManagerBuilder {
142 public:
143   PassManagerBuilderWrapper(const CodeGenOptions &CGOpts,
144                             const LangOptions &LangOpts)
145       : PassManagerBuilder(), CGOpts(CGOpts), LangOpts(LangOpts) {}
146   const CodeGenOptions &getCGOpts() const { return CGOpts; }
147   const LangOptions &getLangOpts() const { return LangOpts; }
148 private:
149   const CodeGenOptions &CGOpts;
150   const LangOptions &LangOpts;
151 };
152 
153 }
154 
155 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
156   if (Builder.OptLevel > 0)
157     PM.add(createObjCARCAPElimPass());
158 }
159 
160 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
161   if (Builder.OptLevel > 0)
162     PM.add(createObjCARCExpandPass());
163 }
164 
165 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
166   if (Builder.OptLevel > 0)
167     PM.add(createObjCARCOptPass());
168 }
169 
170 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
171                                     PassManagerBase &PM) {
172   PM.add(createBoundsCheckingPass());
173 }
174 
175 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
176                                       PassManagerBase &PM) {
177   const PassManagerBuilderWrapper &BuilderWrapper =
178       static_cast<const PassManagerBuilderWrapper&>(Builder);
179   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
180   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
181   PM.add(createAddressSanitizerFunctionPass(LangOpts.SanitizeInitOrder,
182                                             LangOpts.SanitizeUseAfterReturn,
183                                             LangOpts.SanitizeUseAfterScope,
184                                             CGOpts.SanitizerBlacklistFile));
185   PM.add(createAddressSanitizerModulePass(LangOpts.SanitizeInitOrder,
186                                           CGOpts.SanitizerBlacklistFile));
187 }
188 
189 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
190                                    PassManagerBase &PM) {
191   const PassManagerBuilderWrapper &BuilderWrapper =
192       static_cast<const PassManagerBuilderWrapper&>(Builder);
193   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
194   PM.add(createMemorySanitizerPass(CGOpts.MemorySanitizerTrackOrigins,
195                                    CGOpts.SanitizerBlacklistFile));
196 }
197 
198 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
199                                    PassManagerBase &PM) {
200   const PassManagerBuilderWrapper &BuilderWrapper =
201       static_cast<const PassManagerBuilderWrapper&>(Builder);
202   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
203   PM.add(createThreadSanitizerPass(CGOpts.SanitizerBlacklistFile));
204 }
205 
206 void EmitAssemblyHelper::CreatePasses(TargetMachine *TM) {
207   unsigned OptLevel = CodeGenOpts.OptimizationLevel;
208   CodeGenOptions::InliningMethod Inlining = CodeGenOpts.getInlining();
209 
210   // Handle disabling of LLVM optimization, where we want to preserve the
211   // internal module before any optimization.
212   if (CodeGenOpts.DisableLLVMOpts) {
213     OptLevel = 0;
214     Inlining = CodeGenOpts.NoInlining;
215   }
216 
217   PassManagerBuilderWrapper PMBuilder(CodeGenOpts, LangOpts);
218   PMBuilder.OptLevel = OptLevel;
219   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
220 
221   PMBuilder.DisableSimplifyLibCalls = !CodeGenOpts.SimplifyLibCalls;
222   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
223   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
224 
225   // In ObjC ARC mode, add the main ARC optimization passes.
226   if (LangOpts.ObjCAutoRefCount) {
227     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
228                            addObjCARCExpandPass);
229     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
230                            addObjCARCAPElimPass);
231     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
232                            addObjCARCOptPass);
233   }
234 
235   if (LangOpts.SanitizeBounds) {
236     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
237                            addBoundsCheckingPass);
238     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
239                            addBoundsCheckingPass);
240   }
241 
242   if (LangOpts.SanitizeAddress) {
243     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
244                            addAddressSanitizerPasses);
245     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
246                            addAddressSanitizerPasses);
247   }
248 
249   if (LangOpts.SanitizeMemory) {
250     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
251                            addMemorySanitizerPass);
252     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
253                            addMemorySanitizerPass);
254   }
255 
256   if (LangOpts.SanitizeThread) {
257     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
258                            addThreadSanitizerPass);
259     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
260                            addThreadSanitizerPass);
261   }
262 
263   // Figure out TargetLibraryInfo.
264   Triple TargetTriple(TheModule->getTargetTriple());
265   PMBuilder.LibraryInfo = new TargetLibraryInfo(TargetTriple);
266   if (!CodeGenOpts.SimplifyLibCalls)
267     PMBuilder.LibraryInfo->disableAllFunctions();
268 
269   switch (Inlining) {
270   case CodeGenOptions::NoInlining: break;
271   case CodeGenOptions::NormalInlining: {
272     // FIXME: Derive these constants in a principled fashion.
273     unsigned Threshold = 225;
274     if (CodeGenOpts.OptimizeSize == 1)      // -Os
275       Threshold = 75;
276     else if (CodeGenOpts.OptimizeSize == 2) // -Oz
277       Threshold = 25;
278     else if (OptLevel > 2)
279       Threshold = 275;
280     PMBuilder.Inliner = createFunctionInliningPass(Threshold);
281     break;
282   }
283   case CodeGenOptions::OnlyAlwaysInlining:
284     // Respect always_inline.
285     if (OptLevel == 0)
286       // Do not insert lifetime intrinsics at -O0.
287       PMBuilder.Inliner = createAlwaysInlinerPass(false);
288     else
289       PMBuilder.Inliner = createAlwaysInlinerPass();
290     break;
291   }
292 
293   // Set up the per-function pass manager.
294   FunctionPassManager *FPM = getPerFunctionPasses(TM);
295   if (CodeGenOpts.VerifyModule)
296     FPM->add(createVerifierPass());
297   PMBuilder.populateFunctionPassManager(*FPM);
298 
299   // Set up the per-module pass manager.
300   PassManager *MPM = getPerModulePasses(TM);
301 
302   if (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes) {
303     MPM->add(createGCOVProfilerPass(CodeGenOpts.EmitGcovNotes,
304                                     CodeGenOpts.EmitGcovArcs,
305                                     TargetTriple.isMacOSX(),
306                                     false,
307                                     CodeGenOpts.DisableRedZone));
308 
309     if (CodeGenOpts.getDebugInfo() == CodeGenOptions::NoDebugInfo)
310       MPM->add(createStripSymbolsPass(true));
311   }
312 
313   PMBuilder.populateModulePassManager(*MPM);
314 }
315 
316 TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
317   // Create the TargetMachine for generating code.
318   std::string Error;
319   std::string Triple = TheModule->getTargetTriple();
320   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
321   if (!TheTarget) {
322     if (MustCreateTM)
323       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
324     return 0;
325   }
326 
327   // FIXME: Expose these capabilities via actual APIs!!!! Aside from just
328   // being gross, this is also totally broken if we ever care about
329   // concurrency.
330 
331   TargetMachine::setAsmVerbosityDefault(CodeGenOpts.AsmVerbose);
332 
333   TargetMachine::setFunctionSections(CodeGenOpts.FunctionSections);
334   TargetMachine::setDataSections    (CodeGenOpts.DataSections);
335 
336   // FIXME: Parse this earlier.
337   llvm::CodeModel::Model CM;
338   if (CodeGenOpts.CodeModel == "small") {
339     CM = llvm::CodeModel::Small;
340   } else if (CodeGenOpts.CodeModel == "kernel") {
341     CM = llvm::CodeModel::Kernel;
342   } else if (CodeGenOpts.CodeModel == "medium") {
343     CM = llvm::CodeModel::Medium;
344   } else if (CodeGenOpts.CodeModel == "large") {
345     CM = llvm::CodeModel::Large;
346   } else {
347     assert(CodeGenOpts.CodeModel.empty() && "Invalid code model!");
348     CM = llvm::CodeModel::Default;
349   }
350 
351   SmallVector<const char *, 16> BackendArgs;
352   BackendArgs.push_back("clang"); // Fake program name.
353   if (!CodeGenOpts.DebugPass.empty()) {
354     BackendArgs.push_back("-debug-pass");
355     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
356   }
357   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
358     BackendArgs.push_back("-limit-float-precision");
359     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
360   }
361   if (llvm::TimePassesIsEnabled)
362     BackendArgs.push_back("-time-passes");
363   for (unsigned i = 0, e = CodeGenOpts.BackendOptions.size(); i != e; ++i)
364     BackendArgs.push_back(CodeGenOpts.BackendOptions[i].c_str());
365   if (CodeGenOpts.NoGlobalMerge)
366     BackendArgs.push_back("-global-merge=false");
367   BackendArgs.push_back(0);
368   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
369                                     BackendArgs.data());
370 
371   std::string FeaturesStr;
372   if (TargetOpts.Features.size()) {
373     SubtargetFeatures Features;
374     for (std::vector<std::string>::const_iterator
375            it = TargetOpts.Features.begin(),
376            ie = TargetOpts.Features.end(); it != ie; ++it)
377       Features.AddFeature(*it);
378     FeaturesStr = Features.getString();
379   }
380 
381   llvm::Reloc::Model RM = llvm::Reloc::Default;
382   if (CodeGenOpts.RelocationModel == "static") {
383     RM = llvm::Reloc::Static;
384   } else if (CodeGenOpts.RelocationModel == "pic") {
385     RM = llvm::Reloc::PIC_;
386   } else {
387     assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
388            "Invalid PIC model!");
389     RM = llvm::Reloc::DynamicNoPIC;
390   }
391 
392   CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
393   switch (CodeGenOpts.OptimizationLevel) {
394   default: break;
395   case 0: OptLevel = CodeGenOpt::None; break;
396   case 3: OptLevel = CodeGenOpt::Aggressive; break;
397   }
398 
399   llvm::TargetOptions Options;
400 
401   // Set frame pointer elimination mode.
402   if (!CodeGenOpts.DisableFPElim) {
403     Options.NoFramePointerElim = false;
404     Options.NoFramePointerElimNonLeaf = false;
405   } else if (CodeGenOpts.OmitLeafFramePointer) {
406     Options.NoFramePointerElim = false;
407     Options.NoFramePointerElimNonLeaf = true;
408   } else {
409     Options.NoFramePointerElim = true;
410     Options.NoFramePointerElimNonLeaf = true;
411   }
412 
413   if (CodeGenOpts.UseInitArray)
414     Options.UseInitArray = true;
415 
416   // Set float ABI type.
417   if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
418     Options.FloatABIType = llvm::FloatABI::Soft;
419   else if (CodeGenOpts.FloatABI == "hard")
420     Options.FloatABIType = llvm::FloatABI::Hard;
421   else {
422     assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
423     Options.FloatABIType = llvm::FloatABI::Default;
424   }
425 
426   // Set FP fusion mode.
427   switch (CodeGenOpts.getFPContractMode()) {
428   case CodeGenOptions::FPC_Off:
429     Options.AllowFPOpFusion = llvm::FPOpFusion::Strict;
430     break;
431   case CodeGenOptions::FPC_On:
432     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
433     break;
434   case CodeGenOptions::FPC_Fast:
435     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
436     break;
437   }
438 
439   Options.LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
440   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
441   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
442   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
443   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
444   Options.UseSoftFloat = CodeGenOpts.SoftFloat;
445   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
446   Options.RealignStack = CodeGenOpts.StackRealignment;
447   Options.DisableTailCalls = CodeGenOpts.DisableTailCalls;
448   Options.TrapFuncName = CodeGenOpts.TrapFuncName;
449   Options.PositionIndependentExecutable = LangOpts.PIELevel != 0;
450   Options.SSPBufferSize = CodeGenOpts.SSPBufferSize;
451 
452   TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
453                                                      FeaturesStr, Options,
454                                                      RM, CM, OptLevel);
455 
456   if (CodeGenOpts.RelaxAll)
457     TM->setMCRelaxAll(true);
458   if (CodeGenOpts.SaveTempLabels)
459     TM->setMCSaveTempLabels(true);
460   if (CodeGenOpts.NoDwarf2CFIAsm)
461     TM->setMCUseCFI(false);
462   if (!CodeGenOpts.NoDwarfDirectoryAsm)
463     TM->setMCUseDwarfDirectory(true);
464   if (CodeGenOpts.NoExecStack)
465     TM->setMCNoExecStack(true);
466 
467   return TM;
468 }
469 
470 bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
471                                        formatted_raw_ostream &OS,
472                                        TargetMachine *TM) {
473 
474   // Create the code generator passes.
475   PassManager *PM = getCodeGenPasses(TM);
476 
477   // Add LibraryInfo.
478   llvm::Triple TargetTriple(TheModule->getTargetTriple());
479   TargetLibraryInfo *TLI = new TargetLibraryInfo(TargetTriple);
480   if (!CodeGenOpts.SimplifyLibCalls)
481     TLI->disableAllFunctions();
482   PM->add(TLI);
483 
484   // Add TargetTransformInfo.
485   PM->add(new TargetTransformInfo(TM->getScalarTargetTransformInfo(),
486                                   TM->getVectorTargetTransformInfo()));
487 
488   // Normal mode, emit a .s or .o file by running the code generator. Note,
489   // this also adds codegenerator level optimization passes.
490   TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
491   if (Action == Backend_EmitObj)
492     CGFT = TargetMachine::CGFT_ObjectFile;
493   else if (Action == Backend_EmitMCNull)
494     CGFT = TargetMachine::CGFT_Null;
495   else
496     assert(Action == Backend_EmitAssembly && "Invalid action!");
497 
498   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
499   // "codegen" passes so that it isn't run multiple times when there is
500   // inlining happening.
501   if (LangOpts.ObjCAutoRefCount &&
502       CodeGenOpts.OptimizationLevel > 0)
503     PM->add(createObjCARCContractPass());
504 
505   if (TM->addPassesToEmitFile(*PM, OS, CGFT,
506                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
507     Diags.Report(diag::err_fe_unable_to_interface_with_target);
508     return false;
509   }
510 
511   return true;
512 }
513 
514 void EmitAssemblyHelper::EmitAssembly(BackendAction Action, raw_ostream *OS) {
515   TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : 0);
516   llvm::formatted_raw_ostream FormattedOS;
517 
518   bool UsesCodeGen = (Action != Backend_EmitNothing &&
519                       Action != Backend_EmitBC &&
520                       Action != Backend_EmitLL);
521   TargetMachine *TM = CreateTargetMachine(UsesCodeGen);
522   CreatePasses(TM);
523 
524   switch (Action) {
525   case Backend_EmitNothing:
526     break;
527 
528   case Backend_EmitBC:
529     getPerModulePasses(TM)->add(createBitcodeWriterPass(*OS));
530     break;
531 
532   case Backend_EmitLL:
533     FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
534     getPerModulePasses(TM)->add(createPrintModulePass(&FormattedOS));
535     break;
536 
537   default:
538     FormattedOS.setStream(*OS, formatted_raw_ostream::PRESERVE_STREAM);
539     if (!AddEmitPasses(Action, FormattedOS, TM))
540       return;
541   }
542 
543   // Before executing passes, print the final values of the LLVM options.
544   cl::PrintOptionValues();
545 
546   // Run passes. For now we do all passes at once, but eventually we
547   // would like to have the option of streaming code generation.
548 
549   if (PerFunctionPasses) {
550     PrettyStackTraceString CrashInfo("Per-function optimization");
551 
552     PerFunctionPasses->doInitialization();
553     for (Module::iterator I = TheModule->begin(),
554            E = TheModule->end(); I != E; ++I)
555       if (!I->isDeclaration())
556         PerFunctionPasses->run(*I);
557     PerFunctionPasses->doFinalization();
558   }
559 
560   if (PerModulePasses) {
561     PrettyStackTraceString CrashInfo("Per-module optimization passes");
562     PerModulePasses->run(*TheModule);
563   }
564 
565   if (CodeGenPasses) {
566     PrettyStackTraceString CrashInfo("Code generation");
567     CodeGenPasses->run(*TheModule);
568   }
569 }
570 
571 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
572                               const CodeGenOptions &CGOpts,
573                               const clang::TargetOptions &TOpts,
574                               const LangOptions &LOpts,
575                               Module *M,
576                               BackendAction Action, raw_ostream *OS) {
577   EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
578 
579   AsmHelper.EmitAssembly(Action, OS);
580 }
581