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/Analysis/TargetLibraryInfo.h"
19 #include "llvm/Analysis/TargetTransformInfo.h"
20 #include "llvm/Bitcode/BitcodeWriterPass.h"
21 #include "llvm/CodeGen/RegAllocRegistry.h"
22 #include "llvm/CodeGen/SchedulerRegistry.h"
23 #include "llvm/IR/DataLayout.h"
24 #include "llvm/IR/IRPrintingPasses.h"
25 #include "llvm/IR/LegacyPassManager.h"
26 #include "llvm/IR/Module.h"
27 #include "llvm/IR/Verifier.h"
28 #include "llvm/MC/SubtargetFeature.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/PrettyStackTrace.h"
31 #include "llvm/Support/TargetRegistry.h"
32 #include "llvm/Support/Timer.h"
33 #include "llvm/Support/raw_ostream.h"
34 #include "llvm/Target/TargetMachine.h"
35 #include "llvm/Target/TargetOptions.h"
36 #include "llvm/Target/TargetSubtargetInfo.h"
37 #include "llvm/Transforms/IPO.h"
38 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
39 #include "llvm/Transforms/Instrumentation.h"
40 #include "llvm/Transforms/ObjCARC.h"
41 #include "llvm/Transforms/Scalar.h"
42 #include "llvm/Transforms/Utils/SymbolRewriter.h"
43 #include <memory>
44 using namespace clang;
45 using namespace llvm;
46 
47 namespace {
48 
49 class EmitAssemblyHelper {
50   DiagnosticsEngine &Diags;
51   const CodeGenOptions &CodeGenOpts;
52   const clang::TargetOptions &TargetOpts;
53   const LangOptions &LangOpts;
54   Module *TheModule;
55 
56   Timer CodeGenerationTime;
57 
58   mutable legacy::PassManager *CodeGenPasses;
59   mutable legacy::PassManager *PerModulePasses;
60   mutable legacy::FunctionPassManager *PerFunctionPasses;
61 
62 private:
63   TargetIRAnalysis getTargetIRAnalysis() const {
64     if (TM)
65       return TM->getTargetIRAnalysis();
66 
67     return TargetIRAnalysis();
68   }
69 
70   legacy::PassManager *getCodeGenPasses() const {
71     if (!CodeGenPasses) {
72       CodeGenPasses = new legacy::PassManager();
73       CodeGenPasses->add(
74           createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
75     }
76     return CodeGenPasses;
77   }
78 
79   legacy::PassManager *getPerModulePasses() const {
80     if (!PerModulePasses) {
81       PerModulePasses = new legacy::PassManager();
82       PerModulePasses->add(
83           createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
84     }
85     return PerModulePasses;
86   }
87 
88   legacy::FunctionPassManager *getPerFunctionPasses() const {
89     if (!PerFunctionPasses) {
90       PerFunctionPasses = new legacy::FunctionPassManager(TheModule);
91       PerFunctionPasses->add(
92           createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
93     }
94     return PerFunctionPasses;
95   }
96 
97   void CreatePasses();
98 
99   /// Generates the TargetMachine.
100   /// Returns Null if it is unable to create the target machine.
101   /// Some of our clang tests specify triples which are not built
102   /// into clang. This is okay because these tests check the generated
103   /// IR, and they require DataLayout which depends on the triple.
104   /// In this case, we allow this method to fail and not report an error.
105   /// When MustCreateTM is used, we print an error if we are unable to load
106   /// the requested target.
107   TargetMachine *CreateTargetMachine(bool MustCreateTM);
108 
109   /// Add passes necessary to emit assembly or LLVM IR.
110   ///
111   /// \return True on success.
112   bool AddEmitPasses(BackendAction Action, raw_pwrite_stream &OS);
113 
114 public:
115   EmitAssemblyHelper(DiagnosticsEngine &_Diags,
116                      const CodeGenOptions &CGOpts,
117                      const clang::TargetOptions &TOpts,
118                      const LangOptions &LOpts,
119                      Module *M)
120     : Diags(_Diags), CodeGenOpts(CGOpts), TargetOpts(TOpts), LangOpts(LOpts),
121       TheModule(M), CodeGenerationTime("Code Generation Time"),
122       CodeGenPasses(nullptr), PerModulePasses(nullptr),
123       PerFunctionPasses(nullptr) {}
124 
125   ~EmitAssemblyHelper() {
126     delete CodeGenPasses;
127     delete PerModulePasses;
128     delete PerFunctionPasses;
129     if (CodeGenOpts.DisableFree)
130       BuryPointer(std::move(TM));
131   }
132 
133   std::unique_ptr<TargetMachine> TM;
134 
135   void EmitAssembly(BackendAction Action, raw_pwrite_stream *OS);
136 };
137 
138 // We need this wrapper to access LangOpts and CGOpts from extension functions
139 // that we add to the PassManagerBuilder.
140 class PassManagerBuilderWrapper : public PassManagerBuilder {
141 public:
142   PassManagerBuilderWrapper(const CodeGenOptions &CGOpts,
143                             const LangOptions &LangOpts)
144       : PassManagerBuilder(), CGOpts(CGOpts), LangOpts(LangOpts) {}
145   const CodeGenOptions &getCGOpts() const { return CGOpts; }
146   const LangOptions &getLangOpts() const { return LangOpts; }
147 private:
148   const CodeGenOptions &CGOpts;
149   const LangOptions &LangOpts;
150 };
151 
152 }
153 
154 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
155   if (Builder.OptLevel > 0)
156     PM.add(createObjCARCAPElimPass());
157 }
158 
159 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
160   if (Builder.OptLevel > 0)
161     PM.add(createObjCARCExpandPass());
162 }
163 
164 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
165   if (Builder.OptLevel > 0)
166     PM.add(createObjCARCOptPass());
167 }
168 
169 static void addSampleProfileLoaderPass(const PassManagerBuilder &Builder,
170                                        legacy::PassManagerBase &PM) {
171   const PassManagerBuilderWrapper &BuilderWrapper =
172       static_cast<const PassManagerBuilderWrapper &>(Builder);
173   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
174   PM.add(createSampleProfileLoaderPass(CGOpts.SampleProfileFile));
175 }
176 
177 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
178                                      legacy::PassManagerBase &PM) {
179   PM.add(createAddDiscriminatorsPass());
180 }
181 
182 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
183                                     legacy::PassManagerBase &PM) {
184   PM.add(createBoundsCheckingPass());
185 }
186 
187 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
188                                      legacy::PassManagerBase &PM) {
189   const PassManagerBuilderWrapper &BuilderWrapper =
190       static_cast<const PassManagerBuilderWrapper&>(Builder);
191   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
192   SanitizerCoverageOptions Opts;
193   Opts.CoverageType =
194       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
195   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
196   Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
197   Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
198   Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
199   PM.add(createSanitizerCoverageModulePass(Opts));
200 }
201 
202 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
203                                       legacy::PassManagerBase &PM) {
204   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/false));
205   PM.add(createAddressSanitizerModulePass(/*CompileKernel*/false));
206 }
207 
208 static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
209                                             legacy::PassManagerBase &PM) {
210   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/true));
211   PM.add(createAddressSanitizerModulePass(/*CompileKernel*/true));
212 }
213 
214 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
215                                    legacy::PassManagerBase &PM) {
216   const PassManagerBuilderWrapper &BuilderWrapper =
217       static_cast<const PassManagerBuilderWrapper&>(Builder);
218   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
219   PM.add(createMemorySanitizerPass(CGOpts.SanitizeMemoryTrackOrigins));
220 
221   // MemorySanitizer inserts complex instrumentation that mostly follows
222   // the logic of the original code, but operates on "shadow" values.
223   // It can benefit from re-running some general purpose optimization passes.
224   if (Builder.OptLevel > 0) {
225     PM.add(createEarlyCSEPass());
226     PM.add(createReassociatePass());
227     PM.add(createLICMPass());
228     PM.add(createGVNPass());
229     PM.add(createInstructionCombiningPass());
230     PM.add(createDeadStoreEliminationPass());
231   }
232 }
233 
234 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
235                                    legacy::PassManagerBase &PM) {
236   PM.add(createThreadSanitizerPass());
237 }
238 
239 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
240                                      legacy::PassManagerBase &PM) {
241   const PassManagerBuilderWrapper &BuilderWrapper =
242       static_cast<const PassManagerBuilderWrapper&>(Builder);
243   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
244   PM.add(createDataFlowSanitizerPass(LangOpts.SanitizerBlacklistFiles));
245 }
246 
247 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
248                                          const CodeGenOptions &CodeGenOpts) {
249   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
250   if (!CodeGenOpts.SimplifyLibCalls)
251     TLII->disableAllFunctions();
252 
253   switch (CodeGenOpts.getVecLib()) {
254   case CodeGenOptions::Accelerate:
255     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
256     break;
257   default:
258     break;
259   }
260   return TLII;
261 }
262 
263 static void addSymbolRewriterPass(const CodeGenOptions &Opts,
264                                   legacy::PassManager *MPM) {
265   llvm::SymbolRewriter::RewriteDescriptorList DL;
266 
267   llvm::SymbolRewriter::RewriteMapParser MapParser;
268   for (const auto &MapFile : Opts.RewriteMapFiles)
269     MapParser.parse(MapFile, &DL);
270 
271   MPM->add(createRewriteSymbolsPass(DL));
272 }
273 
274 void EmitAssemblyHelper::CreatePasses() {
275   if (CodeGenOpts.DisableLLVMPasses)
276     return;
277 
278   unsigned OptLevel = CodeGenOpts.OptimizationLevel;
279   CodeGenOptions::InliningMethod Inlining = CodeGenOpts.getInlining();
280 
281   // Handle disabling of LLVM optimization, where we want to preserve the
282   // internal module before any optimization.
283   if (CodeGenOpts.DisableLLVMOpts) {
284     OptLevel = 0;
285     Inlining = CodeGenOpts.NoInlining;
286   }
287 
288   PassManagerBuilderWrapper PMBuilder(CodeGenOpts, LangOpts);
289   PMBuilder.OptLevel = OptLevel;
290   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
291   PMBuilder.BBVectorize = CodeGenOpts.VectorizeBB;
292   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
293   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
294 
295   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
296   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
297   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
298   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
299   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
300 
301   PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
302                          addAddDiscriminatorsPass);
303 
304   if (!CodeGenOpts.SampleProfileFile.empty())
305     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
306                            addSampleProfileLoaderPass);
307 
308   // In ObjC ARC mode, add the main ARC optimization passes.
309   if (LangOpts.ObjCAutoRefCount) {
310     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
311                            addObjCARCExpandPass);
312     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
313                            addObjCARCAPElimPass);
314     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
315                            addObjCARCOptPass);
316   }
317 
318   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
319     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
320                            addBoundsCheckingPass);
321     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
322                            addBoundsCheckingPass);
323   }
324 
325   if (CodeGenOpts.SanitizeCoverageType ||
326       CodeGenOpts.SanitizeCoverageIndirectCalls ||
327       CodeGenOpts.SanitizeCoverageTraceCmp) {
328     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
329                            addSanitizerCoveragePass);
330     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
331                            addSanitizerCoveragePass);
332   }
333 
334   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
335     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
336                            addAddressSanitizerPasses);
337     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
338                            addAddressSanitizerPasses);
339   }
340 
341   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
342     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
343                            addKernelAddressSanitizerPasses);
344     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
345                            addKernelAddressSanitizerPasses);
346   }
347 
348   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
349     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
350                            addMemorySanitizerPass);
351     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
352                            addMemorySanitizerPass);
353   }
354 
355   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
356     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
357                            addThreadSanitizerPass);
358     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
359                            addThreadSanitizerPass);
360   }
361 
362   if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
363     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
364                            addDataFlowSanitizerPass);
365     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
366                            addDataFlowSanitizerPass);
367   }
368 
369   // Figure out TargetLibraryInfo.
370   Triple TargetTriple(TheModule->getTargetTriple());
371   PMBuilder.LibraryInfo = createTLII(TargetTriple, CodeGenOpts);
372 
373   switch (Inlining) {
374   case CodeGenOptions::NoInlining: break;
375   case CodeGenOptions::NormalInlining: {
376     PMBuilder.Inliner =
377         createFunctionInliningPass(OptLevel, CodeGenOpts.OptimizeSize);
378     break;
379   }
380   case CodeGenOptions::OnlyAlwaysInlining:
381     // Respect always_inline.
382     if (OptLevel == 0)
383       // Do not insert lifetime intrinsics at -O0.
384       PMBuilder.Inliner = createAlwaysInlinerPass(false);
385     else
386       PMBuilder.Inliner = createAlwaysInlinerPass();
387     break;
388   }
389 
390   // Set up the per-function pass manager.
391   legacy::FunctionPassManager *FPM = getPerFunctionPasses();
392   if (CodeGenOpts.VerifyModule)
393     FPM->add(createVerifierPass());
394   PMBuilder.populateFunctionPassManager(*FPM);
395 
396   // Set up the per-module pass manager.
397   legacy::PassManager *MPM = getPerModulePasses();
398   if (!CodeGenOpts.RewriteMapFiles.empty())
399     addSymbolRewriterPass(CodeGenOpts, MPM);
400 
401   if (!CodeGenOpts.DisableGCov &&
402       (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes)) {
403     // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
404     // LLVM's -default-gcov-version flag is set to something invalid.
405     GCOVOptions Options;
406     Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
407     Options.EmitData = CodeGenOpts.EmitGcovArcs;
408     memcpy(Options.Version, CodeGenOpts.CoverageVersion, 4);
409     Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
410     Options.NoRedZone = CodeGenOpts.DisableRedZone;
411     Options.FunctionNamesInData =
412         !CodeGenOpts.CoverageNoFunctionNamesInData;
413     Options.ExitBlockBeforeBody = CodeGenOpts.CoverageExitBlockBeforeBody;
414     MPM->add(createGCOVProfilerPass(Options));
415     if (CodeGenOpts.getDebugInfo() == CodeGenOptions::NoDebugInfo)
416       MPM->add(createStripSymbolsPass(true));
417   }
418 
419   if (CodeGenOpts.ProfileInstrGenerate) {
420     InstrProfOptions Options;
421     Options.NoRedZone = CodeGenOpts.DisableRedZone;
422     Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
423     MPM->add(createInstrProfilingPass(Options));
424   }
425 
426   PMBuilder.populateModulePassManager(*MPM);
427 }
428 
429 TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
430   // Create the TargetMachine for generating code.
431   std::string Error;
432   std::string Triple = TheModule->getTargetTriple();
433   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
434   if (!TheTarget) {
435     if (MustCreateTM)
436       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
437     return nullptr;
438   }
439 
440   unsigned CodeModel =
441     llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
442       .Case("small", llvm::CodeModel::Small)
443       .Case("kernel", llvm::CodeModel::Kernel)
444       .Case("medium", llvm::CodeModel::Medium)
445       .Case("large", llvm::CodeModel::Large)
446       .Case("default", llvm::CodeModel::Default)
447       .Default(~0u);
448   assert(CodeModel != ~0u && "invalid code model!");
449   llvm::CodeModel::Model CM = static_cast<llvm::CodeModel::Model>(CodeModel);
450 
451   SmallVector<const char *, 16> BackendArgs;
452   BackendArgs.push_back("clang"); // Fake program name.
453   if (!CodeGenOpts.DebugPass.empty()) {
454     BackendArgs.push_back("-debug-pass");
455     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
456   }
457   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
458     BackendArgs.push_back("-limit-float-precision");
459     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
460   }
461   for (const std::string &BackendOption : CodeGenOpts.BackendOptions)
462     BackendArgs.push_back(BackendOption.c_str());
463   BackendArgs.push_back(nullptr);
464   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
465                                     BackendArgs.data());
466 
467   std::string FeaturesStr;
468   if (!TargetOpts.Features.empty()) {
469     SubtargetFeatures Features;
470     for (const std::string &Feature : TargetOpts.Features)
471       Features.AddFeature(Feature);
472     FeaturesStr = Features.getString();
473   }
474 
475   llvm::Reloc::Model RM = llvm::Reloc::Default;
476   if (CodeGenOpts.RelocationModel == "static") {
477     RM = llvm::Reloc::Static;
478   } else if (CodeGenOpts.RelocationModel == "pic") {
479     RM = llvm::Reloc::PIC_;
480   } else {
481     assert(CodeGenOpts.RelocationModel == "dynamic-no-pic" &&
482            "Invalid PIC model!");
483     RM = llvm::Reloc::DynamicNoPIC;
484   }
485 
486   CodeGenOpt::Level OptLevel = CodeGenOpt::Default;
487   switch (CodeGenOpts.OptimizationLevel) {
488   default: break;
489   case 0: OptLevel = CodeGenOpt::None; break;
490   case 3: OptLevel = CodeGenOpt::Aggressive; break;
491   }
492 
493   llvm::TargetOptions Options;
494 
495   if (!TargetOpts.Reciprocals.empty())
496     Options.Reciprocals = TargetRecip(TargetOpts.Reciprocals);
497 
498   Options.ThreadModel =
499     llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
500       .Case("posix", llvm::ThreadModel::POSIX)
501       .Case("single", llvm::ThreadModel::Single);
502 
503   if (CodeGenOpts.DisableIntegratedAS)
504     Options.DisableIntegratedAS = true;
505 
506   if (CodeGenOpts.CompressDebugSections)
507     Options.CompressDebugSections = true;
508 
509   if (CodeGenOpts.UseInitArray)
510     Options.UseInitArray = true;
511 
512   // Set float ABI type.
513   if (CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp")
514     Options.FloatABIType = llvm::FloatABI::Soft;
515   else if (CodeGenOpts.FloatABI == "hard")
516     Options.FloatABIType = llvm::FloatABI::Hard;
517   else {
518     assert(CodeGenOpts.FloatABI.empty() && "Invalid float abi!");
519     Options.FloatABIType = llvm::FloatABI::Default;
520   }
521 
522   // Set FP fusion mode.
523   switch (CodeGenOpts.getFPContractMode()) {
524   case CodeGenOptions::FPC_Off:
525     Options.AllowFPOpFusion = llvm::FPOpFusion::Strict;
526     break;
527   case CodeGenOptions::FPC_On:
528     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
529     break;
530   case CodeGenOptions::FPC_Fast:
531     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
532     break;
533   }
534 
535   Options.LessPreciseFPMADOption = CodeGenOpts.LessPreciseFPMAD;
536   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
537   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
538   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
539   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
540   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
541   Options.PositionIndependentExecutable = LangOpts.PIELevel != 0;
542   Options.FunctionSections = CodeGenOpts.FunctionSections;
543   Options.DataSections = CodeGenOpts.DataSections;
544   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
545   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
546 
547   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
548   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
549   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
550   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
551   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
552   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
553   Options.MCOptions.ABIName = TargetOpts.ABI;
554 
555   TargetMachine *TM = TheTarget->createTargetMachine(Triple, TargetOpts.CPU,
556                                                      FeaturesStr, Options,
557                                                      RM, CM, OptLevel);
558 
559   return TM;
560 }
561 
562 bool EmitAssemblyHelper::AddEmitPasses(BackendAction Action,
563                                        raw_pwrite_stream &OS) {
564 
565   // Create the code generator passes.
566   legacy::PassManager *PM = getCodeGenPasses();
567 
568   // Add LibraryInfo.
569   llvm::Triple TargetTriple(TheModule->getTargetTriple());
570   std::unique_ptr<TargetLibraryInfoImpl> TLII(
571       createTLII(TargetTriple, CodeGenOpts));
572   PM->add(new TargetLibraryInfoWrapperPass(*TLII));
573 
574   // Normal mode, emit a .s or .o file by running the code generator. Note,
575   // this also adds codegenerator level optimization passes.
576   TargetMachine::CodeGenFileType CGFT = TargetMachine::CGFT_AssemblyFile;
577   if (Action == Backend_EmitObj)
578     CGFT = TargetMachine::CGFT_ObjectFile;
579   else if (Action == Backend_EmitMCNull)
580     CGFT = TargetMachine::CGFT_Null;
581   else
582     assert(Action == Backend_EmitAssembly && "Invalid action!");
583 
584   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
585   // "codegen" passes so that it isn't run multiple times when there is
586   // inlining happening.
587   if (CodeGenOpts.OptimizationLevel > 0)
588     PM->add(createObjCARCContractPass());
589 
590   if (TM->addPassesToEmitFile(*PM, OS, CGFT,
591                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
592     Diags.Report(diag::err_fe_unable_to_interface_with_target);
593     return false;
594   }
595 
596   return true;
597 }
598 
599 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
600                                       raw_pwrite_stream *OS) {
601   TimeRegion Region(llvm::TimePassesIsEnabled ? &CodeGenerationTime : nullptr);
602 
603   bool UsesCodeGen = (Action != Backend_EmitNothing &&
604                       Action != Backend_EmitBC &&
605                       Action != Backend_EmitLL);
606   if (!TM)
607     TM.reset(CreateTargetMachine(UsesCodeGen));
608 
609   if (UsesCodeGen && !TM)
610     return;
611   if (TM)
612     TheModule->setDataLayout(TM->createDataLayout());
613   CreatePasses();
614 
615   switch (Action) {
616   case Backend_EmitNothing:
617     break;
618 
619   case Backend_EmitBC:
620     getPerModulePasses()->add(
621         createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists));
622     break;
623 
624   case Backend_EmitLL:
625     getPerModulePasses()->add(
626         createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
627     break;
628 
629   default:
630     if (!AddEmitPasses(Action, *OS))
631       return;
632   }
633 
634   // Before executing passes, print the final values of the LLVM options.
635   cl::PrintOptionValues();
636 
637   // Run passes. For now we do all passes at once, but eventually we
638   // would like to have the option of streaming code generation.
639 
640   if (PerFunctionPasses) {
641     PrettyStackTraceString CrashInfo("Per-function optimization");
642 
643     PerFunctionPasses->doInitialization();
644     for (Function &F : *TheModule)
645       if (!F.isDeclaration())
646         PerFunctionPasses->run(F);
647     PerFunctionPasses->doFinalization();
648   }
649 
650   if (PerModulePasses) {
651     PrettyStackTraceString CrashInfo("Per-module optimization passes");
652     PerModulePasses->run(*TheModule);
653   }
654 
655   if (CodeGenPasses) {
656     PrettyStackTraceString CrashInfo("Code generation");
657     CodeGenPasses->run(*TheModule);
658   }
659 }
660 
661 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
662                               const CodeGenOptions &CGOpts,
663                               const clang::TargetOptions &TOpts,
664                               const LangOptions &LOpts, StringRef TDesc,
665                               Module *M, BackendAction Action,
666                               raw_pwrite_stream *OS) {
667   EmitAssemblyHelper AsmHelper(Diags, CGOpts, TOpts, LOpts, M);
668 
669   AsmHelper.EmitAssembly(Action, OS);
670 
671   // If an optional clang TargetInfo description string was passed in, use it to
672   // verify the LLVM TargetMachine's DataLayout.
673   if (AsmHelper.TM && !TDesc.empty()) {
674     std::string DLDesc = M->getDataLayout().getStringRepresentation();
675     if (DLDesc != TDesc) {
676       unsigned DiagID = Diags.getCustomDiagID(
677           DiagnosticsEngine::Error, "backend data layout '%0' does not match "
678                                     "expected target description '%1'");
679       Diags.Report(DiagID) << DLDesc << TDesc;
680     }
681   }
682 }
683