1 //===--- BackendUtil.cpp - LLVM Backend Utilities -------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "clang/CodeGen/BackendUtil.h"
10 #include "clang/Basic/CodeGenOptions.h"
11 #include "clang/Basic/Diagnostic.h"
12 #include "clang/Basic/LangOptions.h"
13 #include "clang/Basic/TargetOptions.h"
14 #include "clang/Frontend/FrontendDiagnostic.h"
15 #include "clang/Frontend/Utils.h"
16 #include "clang/Lex/HeaderSearchOptions.h"
17 #include "llvm/ADT/SmallSet.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/ADT/StringSwitch.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/Analysis/TargetLibraryInfo.h"
22 #include "llvm/Analysis/TargetTransformInfo.h"
23 #include "llvm/Bitcode/BitcodeReader.h"
24 #include "llvm/Bitcode/BitcodeWriter.h"
25 #include "llvm/Bitcode/BitcodeWriterPass.h"
26 #include "llvm/CodeGen/RegAllocRegistry.h"
27 #include "llvm/CodeGen/SchedulerRegistry.h"
28 #include "llvm/CodeGen/TargetSubtargetInfo.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/IRPrintingPasses.h"
31 #include "llvm/IR/LegacyPassManager.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/ModuleSummaryIndex.h"
34 #include "llvm/IR/Verifier.h"
35 #include "llvm/LTO/LTOBackend.h"
36 #include "llvm/MC/MCAsmInfo.h"
37 #include "llvm/MC/SubtargetFeature.h"
38 #include "llvm/Passes/PassBuilder.h"
39 #include "llvm/Passes/PassPlugin.h"
40 #include "llvm/Passes/StandardInstrumentations.h"
41 #include "llvm/Support/BuryPointer.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/MemoryBuffer.h"
44 #include "llvm/Support/PrettyStackTrace.h"
45 #include "llvm/Support/TargetRegistry.h"
46 #include "llvm/Support/TimeProfiler.h"
47 #include "llvm/Support/Timer.h"
48 #include "llvm/Support/raw_ostream.h"
49 #include "llvm/Target/TargetMachine.h"
50 #include "llvm/Target/TargetOptions.h"
51 #include "llvm/Transforms/Coroutines.h"
52 #include "llvm/Transforms/IPO.h"
53 #include "llvm/Transforms/IPO/AlwaysInliner.h"
54 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
55 #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
56 #include "llvm/Transforms/InstCombine/InstCombine.h"
57 #include "llvm/Transforms/Instrumentation.h"
58 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
59 #include "llvm/Transforms/Instrumentation/BoundsChecking.h"
60 #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
61 #include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
62 #include "llvm/Transforms/Instrumentation/InstrProfiling.h"
63 #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
64 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
65 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
66 #include "llvm/Transforms/ObjCARC.h"
67 #include "llvm/Transforms/Scalar.h"
68 #include "llvm/Transforms/Scalar/GVN.h"
69 #include "llvm/Transforms/Utils.h"
70 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
71 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
72 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
73 #include "llvm/Transforms/Utils/SymbolRewriter.h"
74 #include <memory>
75 using namespace clang;
76 using namespace llvm;
77 
78 #define HANDLE_EXTENSION(Ext)                                                  \
79   llvm::PassPluginLibraryInfo get##Ext##PluginInfo();
80 #include "llvm/Support/Extension.def"
81 
82 namespace {
83 
84 // Default filename used for profile generation.
85 static constexpr StringLiteral DefaultProfileGenName = "default_%m.profraw";
86 
87 class EmitAssemblyHelper {
88   DiagnosticsEngine &Diags;
89   const HeaderSearchOptions &HSOpts;
90   const CodeGenOptions &CodeGenOpts;
91   const clang::TargetOptions &TargetOpts;
92   const LangOptions &LangOpts;
93   Module *TheModule;
94 
95   Timer CodeGenerationTime;
96 
97   std::unique_ptr<raw_pwrite_stream> OS;
98 
99   TargetIRAnalysis getTargetIRAnalysis() const {
100     if (TM)
101       return TM->getTargetIRAnalysis();
102 
103     return TargetIRAnalysis();
104   }
105 
106   void CreatePasses(legacy::PassManager &MPM, legacy::FunctionPassManager &FPM);
107 
108   /// Generates the TargetMachine.
109   /// Leaves TM unchanged if it is unable to create the target machine.
110   /// Some of our clang tests specify triples which are not built
111   /// into clang. This is okay because these tests check the generated
112   /// IR, and they require DataLayout which depends on the triple.
113   /// In this case, we allow this method to fail and not report an error.
114   /// When MustCreateTM is used, we print an error if we are unable to load
115   /// the requested target.
116   void CreateTargetMachine(bool MustCreateTM);
117 
118   /// Add passes necessary to emit assembly or LLVM IR.
119   ///
120   /// \return True on success.
121   bool AddEmitPasses(legacy::PassManager &CodeGenPasses, BackendAction Action,
122                      raw_pwrite_stream &OS, raw_pwrite_stream *DwoOS);
123 
124   std::unique_ptr<llvm::ToolOutputFile> openOutputFile(StringRef Path) {
125     std::error_code EC;
126     auto F = std::make_unique<llvm::ToolOutputFile>(Path, EC,
127                                                      llvm::sys::fs::OF_None);
128     if (EC) {
129       Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
130       F.reset();
131     }
132     return F;
133   }
134 
135 public:
136   EmitAssemblyHelper(DiagnosticsEngine &_Diags,
137                      const HeaderSearchOptions &HeaderSearchOpts,
138                      const CodeGenOptions &CGOpts,
139                      const clang::TargetOptions &TOpts,
140                      const LangOptions &LOpts, Module *M)
141       : Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
142         TargetOpts(TOpts), LangOpts(LOpts), TheModule(M),
143         CodeGenerationTime("codegen", "Code Generation Time") {}
144 
145   ~EmitAssemblyHelper() {
146     if (CodeGenOpts.DisableFree)
147       BuryPointer(std::move(TM));
148   }
149 
150   std::unique_ptr<TargetMachine> TM;
151 
152   void EmitAssembly(BackendAction Action,
153                     std::unique_ptr<raw_pwrite_stream> OS);
154 
155   void EmitAssemblyWithNewPassManager(BackendAction Action,
156                                       std::unique_ptr<raw_pwrite_stream> OS);
157 };
158 
159 // We need this wrapper to access LangOpts and CGOpts from extension functions
160 // that we add to the PassManagerBuilder.
161 class PassManagerBuilderWrapper : public PassManagerBuilder {
162 public:
163   PassManagerBuilderWrapper(const Triple &TargetTriple,
164                             const CodeGenOptions &CGOpts,
165                             const LangOptions &LangOpts)
166       : PassManagerBuilder(), TargetTriple(TargetTriple), CGOpts(CGOpts),
167         LangOpts(LangOpts) {}
168   const Triple &getTargetTriple() const { return TargetTriple; }
169   const CodeGenOptions &getCGOpts() const { return CGOpts; }
170   const LangOptions &getLangOpts() const { return LangOpts; }
171 
172 private:
173   const Triple &TargetTriple;
174   const CodeGenOptions &CGOpts;
175   const LangOptions &LangOpts;
176 };
177 }
178 
179 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
180   if (Builder.OptLevel > 0)
181     PM.add(createObjCARCAPElimPass());
182 }
183 
184 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
185   if (Builder.OptLevel > 0)
186     PM.add(createObjCARCExpandPass());
187 }
188 
189 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
190   if (Builder.OptLevel > 0)
191     PM.add(createObjCARCOptPass());
192 }
193 
194 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
195                                      legacy::PassManagerBase &PM) {
196   PM.add(createAddDiscriminatorsPass());
197 }
198 
199 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
200                                   legacy::PassManagerBase &PM) {
201   PM.add(createBoundsCheckingLegacyPass());
202 }
203 
204 static SanitizerCoverageOptions
205 getSancovOptsFromCGOpts(const CodeGenOptions &CGOpts) {
206   SanitizerCoverageOptions Opts;
207   Opts.CoverageType =
208       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
209   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
210   Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
211   Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
212   Opts.TraceDiv = CGOpts.SanitizeCoverageTraceDiv;
213   Opts.TraceGep = CGOpts.SanitizeCoverageTraceGep;
214   Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
215   Opts.TracePC = CGOpts.SanitizeCoverageTracePC;
216   Opts.TracePCGuard = CGOpts.SanitizeCoverageTracePCGuard;
217   Opts.NoPrune = CGOpts.SanitizeCoverageNoPrune;
218   Opts.Inline8bitCounters = CGOpts.SanitizeCoverageInline8bitCounters;
219   Opts.PCTable = CGOpts.SanitizeCoveragePCTable;
220   Opts.StackDepth = CGOpts.SanitizeCoverageStackDepth;
221   return Opts;
222 }
223 
224 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
225                                      legacy::PassManagerBase &PM) {
226   const PassManagerBuilderWrapper &BuilderWrapper =
227       static_cast<const PassManagerBuilderWrapper &>(Builder);
228   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
229   auto Opts = getSancovOptsFromCGOpts(CGOpts);
230   PM.add(createModuleSanitizerCoverageLegacyPassPass(Opts));
231 }
232 
233 // Check if ASan should use GC-friendly instrumentation for globals.
234 // First of all, there is no point if -fdata-sections is off (expect for MachO,
235 // where this is not a factor). Also, on ELF this feature requires an assembler
236 // extension that only works with -integrated-as at the moment.
237 static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
238   if (!CGOpts.SanitizeAddressGlobalsDeadStripping)
239     return false;
240   switch (T.getObjectFormat()) {
241   case Triple::MachO:
242   case Triple::COFF:
243     return true;
244   case Triple::ELF:
245     return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
246   case Triple::XCOFF:
247     llvm::report_fatal_error("ASan not implemented for XCOFF.");
248   case Triple::Wasm:
249   case Triple::UnknownObjectFormat:
250     break;
251   }
252   return false;
253 }
254 
255 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
256                                       legacy::PassManagerBase &PM) {
257   const PassManagerBuilderWrapper &BuilderWrapper =
258       static_cast<const PassManagerBuilderWrapper&>(Builder);
259   const Triple &T = BuilderWrapper.getTargetTriple();
260   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
261   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
262   bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
263   bool UseOdrIndicator = CGOpts.SanitizeAddressUseOdrIndicator;
264   bool UseGlobalsGC = asanUseGlobalsGC(T, CGOpts);
265   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
266                                             UseAfterScope));
267   PM.add(createModuleAddressSanitizerLegacyPassPass(
268       /*CompileKernel*/ false, Recover, UseGlobalsGC, UseOdrIndicator));
269 }
270 
271 static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
272                                             legacy::PassManagerBase &PM) {
273   PM.add(createAddressSanitizerFunctionPass(
274       /*CompileKernel*/ true, /*Recover*/ true, /*UseAfterScope*/ false));
275   PM.add(createModuleAddressSanitizerLegacyPassPass(
276       /*CompileKernel*/ true, /*Recover*/ true, /*UseGlobalsGC*/ true,
277       /*UseOdrIndicator*/ false));
278 }
279 
280 static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
281                                             legacy::PassManagerBase &PM) {
282   const PassManagerBuilderWrapper &BuilderWrapper =
283       static_cast<const PassManagerBuilderWrapper &>(Builder);
284   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
285   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
286   PM.add(
287       createHWAddressSanitizerLegacyPassPass(/*CompileKernel*/ false, Recover));
288 }
289 
290 static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
291                                             legacy::PassManagerBase &PM) {
292   PM.add(createHWAddressSanitizerLegacyPassPass(
293       /*CompileKernel*/ true, /*Recover*/ true));
294 }
295 
296 static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
297                                              legacy::PassManagerBase &PM,
298                                              bool CompileKernel) {
299   const PassManagerBuilderWrapper &BuilderWrapper =
300       static_cast<const PassManagerBuilderWrapper&>(Builder);
301   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
302   int TrackOrigins = CGOpts.SanitizeMemoryTrackOrigins;
303   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Memory);
304   PM.add(createMemorySanitizerLegacyPassPass(
305       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
306 
307   // MemorySanitizer inserts complex instrumentation that mostly follows
308   // the logic of the original code, but operates on "shadow" values.
309   // It can benefit from re-running some general purpose optimization passes.
310   if (Builder.OptLevel > 0) {
311     PM.add(createEarlyCSEPass());
312     PM.add(createReassociatePass());
313     PM.add(createLICMPass());
314     PM.add(createGVNPass());
315     PM.add(createInstructionCombiningPass());
316     PM.add(createDeadStoreEliminationPass());
317   }
318 }
319 
320 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
321                                    legacy::PassManagerBase &PM) {
322   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ false);
323 }
324 
325 static void addKernelMemorySanitizerPass(const PassManagerBuilder &Builder,
326                                          legacy::PassManagerBase &PM) {
327   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ true);
328 }
329 
330 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
331                                    legacy::PassManagerBase &PM) {
332   PM.add(createThreadSanitizerLegacyPassPass());
333 }
334 
335 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
336                                      legacy::PassManagerBase &PM) {
337   const PassManagerBuilderWrapper &BuilderWrapper =
338       static_cast<const PassManagerBuilderWrapper&>(Builder);
339   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
340   PM.add(createDataFlowSanitizerPass(LangOpts.SanitizerBlacklistFiles));
341 }
342 
343 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
344                                          const CodeGenOptions &CodeGenOpts) {
345   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
346 
347   switch (CodeGenOpts.getVecLib()) {
348   case CodeGenOptions::Accelerate:
349     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
350     break;
351   case CodeGenOptions::MASSV:
352     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::MASSV);
353     break;
354   case CodeGenOptions::SVML:
355     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::SVML);
356     break;
357   default:
358     break;
359   }
360   return TLII;
361 }
362 
363 static void addSymbolRewriterPass(const CodeGenOptions &Opts,
364                                   legacy::PassManager *MPM) {
365   llvm::SymbolRewriter::RewriteDescriptorList DL;
366 
367   llvm::SymbolRewriter::RewriteMapParser MapParser;
368   for (const auto &MapFile : Opts.RewriteMapFiles)
369     MapParser.parse(MapFile, &DL);
370 
371   MPM->add(createRewriteSymbolsPass(DL));
372 }
373 
374 static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
375   switch (CodeGenOpts.OptimizationLevel) {
376   default:
377     llvm_unreachable("Invalid optimization level!");
378   case 0:
379     return CodeGenOpt::None;
380   case 1:
381     return CodeGenOpt::Less;
382   case 2:
383     return CodeGenOpt::Default; // O2/Os/Oz
384   case 3:
385     return CodeGenOpt::Aggressive;
386   }
387 }
388 
389 static Optional<llvm::CodeModel::Model>
390 getCodeModel(const CodeGenOptions &CodeGenOpts) {
391   unsigned CodeModel = llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
392                            .Case("tiny", llvm::CodeModel::Tiny)
393                            .Case("small", llvm::CodeModel::Small)
394                            .Case("kernel", llvm::CodeModel::Kernel)
395                            .Case("medium", llvm::CodeModel::Medium)
396                            .Case("large", llvm::CodeModel::Large)
397                            .Case("default", ~1u)
398                            .Default(~0u);
399   assert(CodeModel != ~0u && "invalid code model!");
400   if (CodeModel == ~1u)
401     return None;
402   return static_cast<llvm::CodeModel::Model>(CodeModel);
403 }
404 
405 static CodeGenFileType getCodeGenFileType(BackendAction Action) {
406   if (Action == Backend_EmitObj)
407     return CGFT_ObjectFile;
408   else if (Action == Backend_EmitMCNull)
409     return CGFT_Null;
410   else {
411     assert(Action == Backend_EmitAssembly && "Invalid action!");
412     return CGFT_AssemblyFile;
413   }
414 }
415 
416 static void initTargetOptions(llvm::TargetOptions &Options,
417                               const CodeGenOptions &CodeGenOpts,
418                               const clang::TargetOptions &TargetOpts,
419                               const LangOptions &LangOpts,
420                               const HeaderSearchOptions &HSOpts) {
421   Options.ThreadModel =
422       llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
423           .Case("posix", llvm::ThreadModel::POSIX)
424           .Case("single", llvm::ThreadModel::Single);
425 
426   // Set float ABI type.
427   assert((CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp" ||
428           CodeGenOpts.FloatABI == "hard" || CodeGenOpts.FloatABI.empty()) &&
429          "Invalid Floating Point ABI!");
430   Options.FloatABIType =
431       llvm::StringSwitch<llvm::FloatABI::ABIType>(CodeGenOpts.FloatABI)
432           .Case("soft", llvm::FloatABI::Soft)
433           .Case("softfp", llvm::FloatABI::Soft)
434           .Case("hard", llvm::FloatABI::Hard)
435           .Default(llvm::FloatABI::Default);
436 
437   // Set FP fusion mode.
438   switch (LangOpts.getDefaultFPContractMode()) {
439   case LangOptions::FPC_Off:
440     // Preserve any contraction performed by the front-end.  (Strict performs
441     // splitting of the muladd intrinsic in the backend.)
442     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
443     break;
444   case LangOptions::FPC_On:
445     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
446     break;
447   case LangOptions::FPC_Fast:
448     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
449     break;
450   }
451 
452   Options.UseInitArray = CodeGenOpts.UseInitArray;
453   Options.DisableIntegratedAS = CodeGenOpts.DisableIntegratedAS;
454   Options.CompressDebugSections = CodeGenOpts.getCompressDebugSections();
455   Options.RelaxELFRelocations = CodeGenOpts.RelaxELFRelocations;
456 
457   // Set EABI version.
458   Options.EABIVersion = TargetOpts.EABIVersion;
459 
460   if (LangOpts.SjLjExceptions)
461     Options.ExceptionModel = llvm::ExceptionHandling::SjLj;
462   if (LangOpts.SEHExceptions)
463     Options.ExceptionModel = llvm::ExceptionHandling::WinEH;
464   if (LangOpts.DWARFExceptions)
465     Options.ExceptionModel = llvm::ExceptionHandling::DwarfCFI;
466   if (LangOpts.WasmExceptions)
467     Options.ExceptionModel = llvm::ExceptionHandling::Wasm;
468 
469   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
470   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
471   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
472   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
473   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
474   Options.FunctionSections = CodeGenOpts.FunctionSections;
475   Options.DataSections = CodeGenOpts.DataSections;
476   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
477   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
478   Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
479   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
480   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
481   Options.EmitAddrsig = CodeGenOpts.Addrsig;
482   Options.EnableDebugEntryValues = CodeGenOpts.EnableDebugEntryValues;
483   Options.ForceDwarfFrameSection = CodeGenOpts.ForceDwarfFrameSection;
484 
485   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
486   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
487   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
488   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
489   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
490   Options.MCOptions.MCIncrementalLinkerCompatible =
491       CodeGenOpts.IncrementalLinkerCompatible;
492   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
493   Options.MCOptions.MCNoWarn = CodeGenOpts.NoWarn;
494   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
495   Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
496   Options.MCOptions.ABIName = TargetOpts.ABI;
497   for (const auto &Entry : HSOpts.UserEntries)
498     if (!Entry.IsFramework &&
499         (Entry.Group == frontend::IncludeDirGroup::Quoted ||
500          Entry.Group == frontend::IncludeDirGroup::Angled ||
501          Entry.Group == frontend::IncludeDirGroup::System))
502       Options.MCOptions.IASSearchPaths.push_back(
503           Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);
504 }
505 static Optional<GCOVOptions> getGCOVOptions(const CodeGenOptions &CodeGenOpts) {
506   if (CodeGenOpts.DisableGCov)
507     return None;
508   if (!CodeGenOpts.EmitGcovArcs && !CodeGenOpts.EmitGcovNotes)
509     return None;
510   // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
511   // LLVM's -default-gcov-version flag is set to something invalid.
512   GCOVOptions Options;
513   Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
514   Options.EmitData = CodeGenOpts.EmitGcovArcs;
515   llvm::copy(CodeGenOpts.CoverageVersion, std::begin(Options.Version));
516   Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
517   Options.NoRedZone = CodeGenOpts.DisableRedZone;
518   Options.FunctionNamesInData = !CodeGenOpts.CoverageNoFunctionNamesInData;
519   Options.Filter = CodeGenOpts.ProfileFilterFiles;
520   Options.Exclude = CodeGenOpts.ProfileExcludeFiles;
521   Options.ExitBlockBeforeBody = CodeGenOpts.CoverageExitBlockBeforeBody;
522   return Options;
523 }
524 
525 static Optional<InstrProfOptions>
526 getInstrProfOptions(const CodeGenOptions &CodeGenOpts,
527                     const LangOptions &LangOpts) {
528   if (!CodeGenOpts.hasProfileClangInstr())
529     return None;
530   InstrProfOptions Options;
531   Options.NoRedZone = CodeGenOpts.DisableRedZone;
532   Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
533 
534   // TODO: Surface the option to emit atomic profile counter increments at
535   // the driver level.
536   Options.Atomic = LangOpts.Sanitize.has(SanitizerKind::Thread);
537   return Options;
538 }
539 
540 void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
541                                       legacy::FunctionPassManager &FPM) {
542   // Handle disabling of all LLVM passes, where we want to preserve the
543   // internal module before any optimization.
544   if (CodeGenOpts.DisableLLVMPasses)
545     return;
546 
547   // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
548   // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
549   // are inserted before PMBuilder ones - they'd get the default-constructed
550   // TLI with an unknown target otherwise.
551   Triple TargetTriple(TheModule->getTargetTriple());
552   std::unique_ptr<TargetLibraryInfoImpl> TLII(
553       createTLII(TargetTriple, CodeGenOpts));
554 
555   PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
556 
557   // At O0 and O1 we only run the always inliner which is more efficient. At
558   // higher optimization levels we run the normal inliner.
559   if (CodeGenOpts.OptimizationLevel <= 1) {
560     bool InsertLifetimeIntrinsics = (CodeGenOpts.OptimizationLevel != 0 &&
561                                      !CodeGenOpts.DisableLifetimeMarkers);
562     PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
563   } else {
564     // We do not want to inline hot callsites for SamplePGO module-summary build
565     // because profile annotation will happen again in ThinLTO backend, and we
566     // want the IR of the hot path to match the profile.
567     PMBuilder.Inliner = createFunctionInliningPass(
568         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
569         (!CodeGenOpts.SampleProfileFile.empty() &&
570          CodeGenOpts.PrepareForThinLTO));
571   }
572 
573   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
574   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
575   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
576   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
577 
578   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
579   // Loop interleaving in the loop vectorizer has historically been set to be
580   // enabled when loop unrolling is enabled.
581   PMBuilder.LoopsInterleaved = CodeGenOpts.UnrollLoops;
582   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
583   PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
584   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
585   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
586 
587   MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
588 
589   if (TM)
590     TM->adjustPassManager(PMBuilder);
591 
592   if (CodeGenOpts.DebugInfoForProfiling ||
593       !CodeGenOpts.SampleProfileFile.empty())
594     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
595                            addAddDiscriminatorsPass);
596 
597   // In ObjC ARC mode, add the main ARC optimization passes.
598   if (LangOpts.ObjCAutoRefCount) {
599     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
600                            addObjCARCExpandPass);
601     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
602                            addObjCARCAPElimPass);
603     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
604                            addObjCARCOptPass);
605   }
606 
607   if (LangOpts.Coroutines)
608     addCoroutinePassesToExtensionPoints(PMBuilder);
609 
610   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
611     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
612                            addBoundsCheckingPass);
613     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
614                            addBoundsCheckingPass);
615   }
616 
617   if (CodeGenOpts.SanitizeCoverageType ||
618       CodeGenOpts.SanitizeCoverageIndirectCalls ||
619       CodeGenOpts.SanitizeCoverageTraceCmp) {
620     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
621                            addSanitizerCoveragePass);
622     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
623                            addSanitizerCoveragePass);
624   }
625 
626   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
627     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
628                            addAddressSanitizerPasses);
629     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
630                            addAddressSanitizerPasses);
631   }
632 
633   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
634     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
635                            addKernelAddressSanitizerPasses);
636     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
637                            addKernelAddressSanitizerPasses);
638   }
639 
640   if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
641     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
642                            addHWAddressSanitizerPasses);
643     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
644                            addHWAddressSanitizerPasses);
645   }
646 
647   if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
648     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
649                            addKernelHWAddressSanitizerPasses);
650     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
651                            addKernelHWAddressSanitizerPasses);
652   }
653 
654   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
655     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
656                            addMemorySanitizerPass);
657     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
658                            addMemorySanitizerPass);
659   }
660 
661   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
662     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
663                            addKernelMemorySanitizerPass);
664     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
665                            addKernelMemorySanitizerPass);
666   }
667 
668   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
669     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
670                            addThreadSanitizerPass);
671     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
672                            addThreadSanitizerPass);
673   }
674 
675   if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
676     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
677                            addDataFlowSanitizerPass);
678     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
679                            addDataFlowSanitizerPass);
680   }
681 
682   // Set up the per-function pass manager.
683   FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
684   if (CodeGenOpts.VerifyModule)
685     FPM.add(createVerifierPass());
686 
687   // Set up the per-module pass manager.
688   if (!CodeGenOpts.RewriteMapFiles.empty())
689     addSymbolRewriterPass(CodeGenOpts, &MPM);
690 
691   if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts)) {
692     MPM.add(createGCOVProfilerPass(*Options));
693     if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
694       MPM.add(createStripSymbolsPass(true));
695   }
696 
697   if (Optional<InstrProfOptions> Options =
698           getInstrProfOptions(CodeGenOpts, LangOpts))
699     MPM.add(createInstrProfilingLegacyPass(*Options, false));
700 
701   bool hasIRInstr = false;
702   if (CodeGenOpts.hasProfileIRInstr()) {
703     PMBuilder.EnablePGOInstrGen = true;
704     hasIRInstr = true;
705   }
706   if (CodeGenOpts.hasProfileCSIRInstr()) {
707     assert(!CodeGenOpts.hasProfileCSIRUse() &&
708            "Cannot have both CSProfileUse pass and CSProfileGen pass at the "
709            "same time");
710     assert(!hasIRInstr &&
711            "Cannot have both ProfileGen pass and CSProfileGen pass at the "
712            "same time");
713     PMBuilder.EnablePGOCSInstrGen = true;
714     hasIRInstr = true;
715   }
716   if (hasIRInstr) {
717     if (!CodeGenOpts.InstrProfileOutput.empty())
718       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
719     else
720       PMBuilder.PGOInstrGen = DefaultProfileGenName;
721   }
722   if (CodeGenOpts.hasProfileIRUse()) {
723     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
724     PMBuilder.EnablePGOCSInstrUse = CodeGenOpts.hasProfileCSIRUse();
725   }
726 
727   if (!CodeGenOpts.SampleProfileFile.empty())
728     PMBuilder.PGOSampleUse = CodeGenOpts.SampleProfileFile;
729 
730   PMBuilder.populateFunctionPassManager(FPM);
731   PMBuilder.populateModulePassManager(MPM);
732 }
733 
734 static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) {
735   SmallVector<const char *, 16> BackendArgs;
736   BackendArgs.push_back("clang"); // Fake program name.
737   if (!CodeGenOpts.DebugPass.empty()) {
738     BackendArgs.push_back("-debug-pass");
739     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
740   }
741   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
742     BackendArgs.push_back("-limit-float-precision");
743     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
744   }
745   BackendArgs.push_back(nullptr);
746   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
747                                     BackendArgs.data());
748 }
749 
750 void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
751   // Create the TargetMachine for generating code.
752   std::string Error;
753   std::string Triple = TheModule->getTargetTriple();
754   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
755   if (!TheTarget) {
756     if (MustCreateTM)
757       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
758     return;
759   }
760 
761   Optional<llvm::CodeModel::Model> CM = getCodeModel(CodeGenOpts);
762   std::string FeaturesStr =
763       llvm::join(TargetOpts.Features.begin(), TargetOpts.Features.end(), ",");
764   llvm::Reloc::Model RM = CodeGenOpts.RelocationModel;
765   CodeGenOpt::Level OptLevel = getCGOptLevel(CodeGenOpts);
766 
767   llvm::TargetOptions Options;
768   initTargetOptions(Options, CodeGenOpts, TargetOpts, LangOpts, HSOpts);
769   TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
770                                           Options, RM, CM, OptLevel));
771 }
772 
773 bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
774                                        BackendAction Action,
775                                        raw_pwrite_stream &OS,
776                                        raw_pwrite_stream *DwoOS) {
777   // Add LibraryInfo.
778   llvm::Triple TargetTriple(TheModule->getTargetTriple());
779   std::unique_ptr<TargetLibraryInfoImpl> TLII(
780       createTLII(TargetTriple, CodeGenOpts));
781   CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
782 
783   // Normal mode, emit a .s or .o file by running the code generator. Note,
784   // this also adds codegenerator level optimization passes.
785   CodeGenFileType CGFT = getCodeGenFileType(Action);
786 
787   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
788   // "codegen" passes so that it isn't run multiple times when there is
789   // inlining happening.
790   if (CodeGenOpts.OptimizationLevel > 0)
791     CodeGenPasses.add(createObjCARCContractPass());
792 
793   if (TM->addPassesToEmitFile(CodeGenPasses, OS, DwoOS, CGFT,
794                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
795     Diags.Report(diag::err_fe_unable_to_interface_with_target);
796     return false;
797   }
798 
799   return true;
800 }
801 
802 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
803                                       std::unique_ptr<raw_pwrite_stream> OS) {
804   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
805 
806   setCommandLineOpts(CodeGenOpts);
807 
808   bool UsesCodeGen = (Action != Backend_EmitNothing &&
809                       Action != Backend_EmitBC &&
810                       Action != Backend_EmitLL);
811   CreateTargetMachine(UsesCodeGen);
812 
813   if (UsesCodeGen && !TM)
814     return;
815   if (TM)
816     TheModule->setDataLayout(TM->createDataLayout());
817 
818   legacy::PassManager PerModulePasses;
819   PerModulePasses.add(
820       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
821 
822   legacy::FunctionPassManager PerFunctionPasses(TheModule);
823   PerFunctionPasses.add(
824       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
825 
826   CreatePasses(PerModulePasses, PerFunctionPasses);
827 
828   legacy::PassManager CodeGenPasses;
829   CodeGenPasses.add(
830       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
831 
832   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
833 
834   switch (Action) {
835   case Backend_EmitNothing:
836     break;
837 
838   case Backend_EmitBC:
839     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
840       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
841         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
842         if (!ThinLinkOS)
843           return;
844       }
845       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
846                                CodeGenOpts.EnableSplitLTOUnit);
847       PerModulePasses.add(createWriteThinLTOBitcodePass(
848           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
849     } else {
850       // Emit a module summary by default for Regular LTO except for ld64
851       // targets
852       bool EmitLTOSummary =
853           (CodeGenOpts.PrepareForLTO &&
854            !CodeGenOpts.DisableLLVMPasses &&
855            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
856                llvm::Triple::Apple);
857       if (EmitLTOSummary) {
858         if (!TheModule->getModuleFlag("ThinLTO"))
859           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
860         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
861                                  uint32_t(1));
862       }
863 
864       PerModulePasses.add(createBitcodeWriterPass(
865           *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
866     }
867     break;
868 
869   case Backend_EmitLL:
870     PerModulePasses.add(
871         createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
872     break;
873 
874   default:
875     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
876       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
877       if (!DwoOS)
878         return;
879     }
880     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
881                        DwoOS ? &DwoOS->os() : nullptr))
882       return;
883   }
884 
885   // Before executing passes, print the final values of the LLVM options.
886   cl::PrintOptionValues();
887 
888   // Run passes. For now we do all passes at once, but eventually we
889   // would like to have the option of streaming code generation.
890 
891   {
892     PrettyStackTraceString CrashInfo("Per-function optimization");
893     llvm::TimeTraceScope TimeScope("PerFunctionPasses");
894 
895     PerFunctionPasses.doInitialization();
896     for (Function &F : *TheModule)
897       if (!F.isDeclaration())
898         PerFunctionPasses.run(F);
899     PerFunctionPasses.doFinalization();
900   }
901 
902   {
903     PrettyStackTraceString CrashInfo("Per-module optimization passes");
904     llvm::TimeTraceScope TimeScope("PerModulePasses");
905     PerModulePasses.run(*TheModule);
906   }
907 
908   {
909     PrettyStackTraceString CrashInfo("Code generation");
910     llvm::TimeTraceScope TimeScope("CodeGenPasses");
911     CodeGenPasses.run(*TheModule);
912   }
913 
914   if (ThinLinkOS)
915     ThinLinkOS->keep();
916   if (DwoOS)
917     DwoOS->keep();
918 }
919 
920 static PassBuilder::OptimizationLevel mapToLevel(const CodeGenOptions &Opts) {
921   switch (Opts.OptimizationLevel) {
922   default:
923     llvm_unreachable("Invalid optimization level!");
924 
925   case 1:
926     return PassBuilder::O1;
927 
928   case 2:
929     switch (Opts.OptimizeSize) {
930     default:
931       llvm_unreachable("Invalid optimization level for size!");
932 
933     case 0:
934       return PassBuilder::O2;
935 
936     case 1:
937       return PassBuilder::Os;
938 
939     case 2:
940       return PassBuilder::Oz;
941     }
942 
943   case 3:
944     return PassBuilder::O3;
945   }
946 }
947 
948 static void addSanitizersAtO0(ModulePassManager &MPM,
949                               const Triple &TargetTriple,
950                               const LangOptions &LangOpts,
951                               const CodeGenOptions &CodeGenOpts) {
952   auto ASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
953     MPM.addPass(RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
954     bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
955     MPM.addPass(createModuleToFunctionPassAdaptor(AddressSanitizerPass(
956         CompileKernel, Recover, CodeGenOpts.SanitizeAddressUseAfterScope)));
957     bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
958     MPM.addPass(
959         ModuleAddressSanitizerPass(CompileKernel, Recover, ModuleUseAfterScope,
960                                    CodeGenOpts.SanitizeAddressUseOdrIndicator));
961   };
962 
963   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
964     ASanPass(SanitizerKind::Address, /*CompileKernel=*/false);
965   }
966 
967   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
968     ASanPass(SanitizerKind::KernelAddress, /*CompileKernel=*/true);
969   }
970 
971   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
972     MPM.addPass(MemorySanitizerPass({}));
973     MPM.addPass(createModuleToFunctionPassAdaptor(MemorySanitizerPass({})));
974   }
975 
976   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
977     MPM.addPass(createModuleToFunctionPassAdaptor(
978         MemorySanitizerPass({0, false, /*Kernel=*/true})));
979   }
980 
981   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
982     MPM.addPass(ThreadSanitizerPass());
983     MPM.addPass(createModuleToFunctionPassAdaptor(ThreadSanitizerPass()));
984   }
985 }
986 
987 /// A clean version of `EmitAssembly` that uses the new pass manager.
988 ///
989 /// Not all features are currently supported in this system, but where
990 /// necessary it falls back to the legacy pass manager to at least provide
991 /// basic functionality.
992 ///
993 /// This API is planned to have its functionality finished and then to replace
994 /// `EmitAssembly` at some point in the future when the default switches.
995 void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
996     BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
997   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
998   setCommandLineOpts(CodeGenOpts);
999 
1000   bool RequiresCodeGen = (Action != Backend_EmitNothing &&
1001                           Action != Backend_EmitBC &&
1002                           Action != Backend_EmitLL);
1003   CreateTargetMachine(RequiresCodeGen);
1004 
1005   if (RequiresCodeGen && !TM)
1006     return;
1007   if (TM)
1008     TheModule->setDataLayout(TM->createDataLayout());
1009 
1010   Optional<PGOOptions> PGOOpt;
1011 
1012   if (CodeGenOpts.hasProfileIRInstr())
1013     // -fprofile-generate.
1014     PGOOpt = PGOOptions(CodeGenOpts.InstrProfileOutput.empty()
1015                             ? DefaultProfileGenName
1016                             : CodeGenOpts.InstrProfileOutput,
1017                         "", "", PGOOptions::IRInstr, PGOOptions::NoCSAction,
1018                         CodeGenOpts.DebugInfoForProfiling);
1019   else if (CodeGenOpts.hasProfileIRUse()) {
1020     // -fprofile-use.
1021     auto CSAction = CodeGenOpts.hasProfileCSIRUse() ? PGOOptions::CSIRUse
1022                                                     : PGOOptions::NoCSAction;
1023     PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "",
1024                         CodeGenOpts.ProfileRemappingFile, PGOOptions::IRUse,
1025                         CSAction, CodeGenOpts.DebugInfoForProfiling);
1026   } else if (!CodeGenOpts.SampleProfileFile.empty())
1027     // -fprofile-sample-use
1028     PGOOpt =
1029         PGOOptions(CodeGenOpts.SampleProfileFile, "",
1030                    CodeGenOpts.ProfileRemappingFile, PGOOptions::SampleUse,
1031                    PGOOptions::NoCSAction, CodeGenOpts.DebugInfoForProfiling);
1032   else if (CodeGenOpts.DebugInfoForProfiling)
1033     // -fdebug-info-for-profiling
1034     PGOOpt = PGOOptions("", "", "", PGOOptions::NoAction,
1035                         PGOOptions::NoCSAction, true);
1036 
1037   // Check to see if we want to generate a CS profile.
1038   if (CodeGenOpts.hasProfileCSIRInstr()) {
1039     assert(!CodeGenOpts.hasProfileCSIRUse() &&
1040            "Cannot have both CSProfileUse pass and CSProfileGen pass at "
1041            "the same time");
1042     if (PGOOpt.hasValue()) {
1043       assert(PGOOpt->Action != PGOOptions::IRInstr &&
1044              PGOOpt->Action != PGOOptions::SampleUse &&
1045              "Cannot run CSProfileGen pass with ProfileGen or SampleUse "
1046              " pass");
1047       PGOOpt->CSProfileGenFile = CodeGenOpts.InstrProfileOutput.empty()
1048                                      ? DefaultProfileGenName
1049                                      : CodeGenOpts.InstrProfileOutput;
1050       PGOOpt->CSAction = PGOOptions::CSIRInstr;
1051     } else
1052       PGOOpt = PGOOptions("",
1053                           CodeGenOpts.InstrProfileOutput.empty()
1054                               ? DefaultProfileGenName
1055                               : CodeGenOpts.InstrProfileOutput,
1056                           "", PGOOptions::NoAction, PGOOptions::CSIRInstr,
1057                           CodeGenOpts.DebugInfoForProfiling);
1058   }
1059 
1060   PipelineTuningOptions PTO;
1061   PTO.LoopUnrolling = CodeGenOpts.UnrollLoops;
1062   // For historical reasons, loop interleaving is set to mirror setting for loop
1063   // unrolling.
1064   PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
1065   PTO.LoopVectorization = CodeGenOpts.VectorizeLoop;
1066   PTO.SLPVectorization = CodeGenOpts.VectorizeSLP;
1067 
1068   PassInstrumentationCallbacks PIC;
1069   StandardInstrumentations SI;
1070   SI.registerCallbacks(PIC);
1071   PassBuilder PB(TM.get(), PTO, PGOOpt, &PIC);
1072 
1073   // Attempt to load pass plugins and register their callbacks with PB.
1074   for (auto &PluginFN : CodeGenOpts.PassPlugins) {
1075     auto PassPlugin = PassPlugin::Load(PluginFN);
1076     if (PassPlugin) {
1077       PassPlugin->registerPassBuilderCallbacks(PB);
1078     } else {
1079       Diags.Report(diag::err_fe_unable_to_load_plugin)
1080           << PluginFN << toString(PassPlugin.takeError());
1081     }
1082   }
1083 #define HANDLE_EXTENSION(Ext)                                                  \
1084   get##Ext##PluginInfo().RegisterPassBuilderCallbacks(PB);
1085 #include "llvm/Support/Extension.def"
1086 
1087   LoopAnalysisManager LAM(CodeGenOpts.DebugPassManager);
1088   FunctionAnalysisManager FAM(CodeGenOpts.DebugPassManager);
1089   CGSCCAnalysisManager CGAM(CodeGenOpts.DebugPassManager);
1090   ModuleAnalysisManager MAM(CodeGenOpts.DebugPassManager);
1091 
1092   // Register the AA manager first so that our version is the one used.
1093   FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
1094 
1095   // Register the target library analysis directly and give it a customized
1096   // preset TLI.
1097   Triple TargetTriple(TheModule->getTargetTriple());
1098   std::unique_ptr<TargetLibraryInfoImpl> TLII(
1099       createTLII(TargetTriple, CodeGenOpts));
1100   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
1101 
1102   // Register all the basic analyses with the managers.
1103   PB.registerModuleAnalyses(MAM);
1104   PB.registerCGSCCAnalyses(CGAM);
1105   PB.registerFunctionAnalyses(FAM);
1106   PB.registerLoopAnalyses(LAM);
1107   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
1108 
1109   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
1110 
1111   if (!CodeGenOpts.DisableLLVMPasses) {
1112     bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
1113     bool IsLTO = CodeGenOpts.PrepareForLTO;
1114 
1115     if (CodeGenOpts.OptimizationLevel == 0) {
1116       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1117         MPM.addPass(GCOVProfilerPass(*Options));
1118       if (Optional<InstrProfOptions> Options =
1119               getInstrProfOptions(CodeGenOpts, LangOpts))
1120         MPM.addPass(InstrProfiling(*Options, false));
1121 
1122       // Build a minimal pipeline based on the semantics required by Clang,
1123       // which is just that always inlining occurs. Further, disable generating
1124       // lifetime intrinsics to avoid enabling further optimizations during
1125       // code generation.
1126       MPM.addPass(AlwaysInlinerPass(/*InsertLifetimeIntrinsics=*/false));
1127 
1128       // At -O0, we can still do PGO. Add all the requested passes for
1129       // instrumentation PGO, if requested.
1130       if (PGOOpt && (PGOOpt->Action == PGOOptions::IRInstr ||
1131                      PGOOpt->Action == PGOOptions::IRUse))
1132         PB.addPGOInstrPassesForO0(
1133             MPM, CodeGenOpts.DebugPassManager,
1134             /* RunProfileGen */ (PGOOpt->Action == PGOOptions::IRInstr),
1135             /* IsCS */ false, PGOOpt->ProfileFile,
1136             PGOOpt->ProfileRemappingFile);
1137 
1138       // At -O0 we directly run necessary sanitizer passes.
1139       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1140         MPM.addPass(createModuleToFunctionPassAdaptor(BoundsCheckingPass()));
1141 
1142       // Lastly, add semantically necessary passes for LTO.
1143       if (IsLTO || IsThinLTO) {
1144         MPM.addPass(CanonicalizeAliasesPass());
1145         MPM.addPass(NameAnonGlobalPass());
1146       }
1147     } else {
1148       // Map our optimization levels into one of the distinct levels used to
1149       // configure the pipeline.
1150       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
1151 
1152       PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1153         MPM.addPass(createModuleToFunctionPassAdaptor(
1154             EntryExitInstrumenterPass(/*PostInlining=*/false)));
1155       });
1156 
1157       // Register callbacks to schedule sanitizer passes at the appropriate part of
1158       // the pipeline.
1159       // FIXME: either handle asan/the remaining sanitizers or error out
1160       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1161         PB.registerScalarOptimizerLateEPCallback(
1162             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1163               FPM.addPass(BoundsCheckingPass());
1164             });
1165       if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
1166         PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1167           MPM.addPass(MemorySanitizerPass({}));
1168         });
1169         PB.registerOptimizerLastEPCallback(
1170             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1171               FPM.addPass(MemorySanitizerPass({}));
1172             });
1173       }
1174       if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
1175         PB.registerPipelineStartEPCallback(
1176             [](ModulePassManager &MPM) { MPM.addPass(ThreadSanitizerPass()); });
1177         PB.registerOptimizerLastEPCallback(
1178             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1179               FPM.addPass(ThreadSanitizerPass());
1180             });
1181       }
1182       if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
1183         PB.registerPipelineStartEPCallback([&](ModulePassManager &MPM) {
1184           MPM.addPass(
1185               RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
1186         });
1187         bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::Address);
1188         bool UseAfterScope = CodeGenOpts.SanitizeAddressUseAfterScope;
1189         PB.registerOptimizerLastEPCallback(
1190             [Recover, UseAfterScope](FunctionPassManager &FPM,
1191                                      PassBuilder::OptimizationLevel Level) {
1192               FPM.addPass(AddressSanitizerPass(
1193                   /*CompileKernel=*/false, Recover, UseAfterScope));
1194             });
1195         bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
1196         bool UseOdrIndicator = CodeGenOpts.SanitizeAddressUseOdrIndicator;
1197         PB.registerPipelineStartEPCallback(
1198             [Recover, ModuleUseAfterScope,
1199              UseOdrIndicator](ModulePassManager &MPM) {
1200               MPM.addPass(ModuleAddressSanitizerPass(
1201                   /*CompileKernel=*/false, Recover, ModuleUseAfterScope,
1202                   UseOdrIndicator));
1203             });
1204       }
1205       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1206         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1207           MPM.addPass(GCOVProfilerPass(*Options));
1208         });
1209       if (Optional<InstrProfOptions> Options =
1210               getInstrProfOptions(CodeGenOpts, LangOpts))
1211         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1212           MPM.addPass(InstrProfiling(*Options, false));
1213         });
1214 
1215       if (IsThinLTO) {
1216         MPM = PB.buildThinLTOPreLinkDefaultPipeline(
1217             Level, CodeGenOpts.DebugPassManager);
1218         MPM.addPass(CanonicalizeAliasesPass());
1219         MPM.addPass(NameAnonGlobalPass());
1220       } else if (IsLTO) {
1221         MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
1222                                                 CodeGenOpts.DebugPassManager);
1223         MPM.addPass(CanonicalizeAliasesPass());
1224         MPM.addPass(NameAnonGlobalPass());
1225       } else {
1226         MPM = PB.buildPerModuleDefaultPipeline(Level,
1227                                                CodeGenOpts.DebugPassManager);
1228       }
1229     }
1230 
1231     if (CodeGenOpts.SanitizeCoverageType ||
1232         CodeGenOpts.SanitizeCoverageIndirectCalls ||
1233         CodeGenOpts.SanitizeCoverageTraceCmp) {
1234       auto SancovOpts = getSancovOptsFromCGOpts(CodeGenOpts);
1235       MPM.addPass(ModuleSanitizerCoveragePass(SancovOpts));
1236     }
1237 
1238     if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
1239       bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
1240       MPM.addPass(HWAddressSanitizerPass(
1241           /*CompileKernel=*/false, Recover));
1242     }
1243     if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
1244       MPM.addPass(HWAddressSanitizerPass(
1245           /*CompileKernel=*/true, /*Recover=*/true));
1246     }
1247 
1248     if (CodeGenOpts.OptimizationLevel == 0) {
1249       addSanitizersAtO0(MPM, TargetTriple, LangOpts, CodeGenOpts);
1250     }
1251   }
1252 
1253   // FIXME: We still use the legacy pass manager to do code generation. We
1254   // create that pass manager here and use it as needed below.
1255   legacy::PassManager CodeGenPasses;
1256   bool NeedCodeGen = false;
1257   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
1258 
1259   // Append any output we need to the pass manager.
1260   switch (Action) {
1261   case Backend_EmitNothing:
1262     break;
1263 
1264   case Backend_EmitBC:
1265     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
1266       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
1267         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
1268         if (!ThinLinkOS)
1269           return;
1270       }
1271       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1272                                CodeGenOpts.EnableSplitLTOUnit);
1273       MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
1274                                                            : nullptr));
1275     } else {
1276       // Emit a module summary by default for Regular LTO except for ld64
1277       // targets
1278       bool EmitLTOSummary =
1279           (CodeGenOpts.PrepareForLTO &&
1280            !CodeGenOpts.DisableLLVMPasses &&
1281            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
1282                llvm::Triple::Apple);
1283       if (EmitLTOSummary) {
1284         if (!TheModule->getModuleFlag("ThinLTO"))
1285           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
1286         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1287                                  uint32_t(1));
1288       }
1289       MPM.addPass(
1290           BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
1291     }
1292     break;
1293 
1294   case Backend_EmitLL:
1295     MPM.addPass(PrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
1296     break;
1297 
1298   case Backend_EmitAssembly:
1299   case Backend_EmitMCNull:
1300   case Backend_EmitObj:
1301     NeedCodeGen = true;
1302     CodeGenPasses.add(
1303         createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
1304     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
1305       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
1306       if (!DwoOS)
1307         return;
1308     }
1309     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
1310                        DwoOS ? &DwoOS->os() : nullptr))
1311       // FIXME: Should we handle this error differently?
1312       return;
1313     break;
1314   }
1315 
1316   // Before executing passes, print the final values of the LLVM options.
1317   cl::PrintOptionValues();
1318 
1319   // Now that we have all of the passes ready, run them.
1320   {
1321     PrettyStackTraceString CrashInfo("Optimizer");
1322     MPM.run(*TheModule, MAM);
1323   }
1324 
1325   // Now if needed, run the legacy PM for codegen.
1326   if (NeedCodeGen) {
1327     PrettyStackTraceString CrashInfo("Code generation");
1328     CodeGenPasses.run(*TheModule);
1329   }
1330 
1331   if (ThinLinkOS)
1332     ThinLinkOS->keep();
1333   if (DwoOS)
1334     DwoOS->keep();
1335 }
1336 
1337 Expected<BitcodeModule> clang::FindThinLTOModule(MemoryBufferRef MBRef) {
1338   Expected<std::vector<BitcodeModule>> BMsOrErr = getBitcodeModuleList(MBRef);
1339   if (!BMsOrErr)
1340     return BMsOrErr.takeError();
1341 
1342   // The bitcode file may contain multiple modules, we want the one that is
1343   // marked as being the ThinLTO module.
1344   if (const BitcodeModule *Bm = FindThinLTOModule(*BMsOrErr))
1345     return *Bm;
1346 
1347   return make_error<StringError>("Could not find module summary",
1348                                  inconvertibleErrorCode());
1349 }
1350 
1351 BitcodeModule *clang::FindThinLTOModule(MutableArrayRef<BitcodeModule> BMs) {
1352   for (BitcodeModule &BM : BMs) {
1353     Expected<BitcodeLTOInfo> LTOInfo = BM.getLTOInfo();
1354     if (LTOInfo && LTOInfo->IsThinLTO)
1355       return &BM;
1356   }
1357   return nullptr;
1358 }
1359 
1360 static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
1361                               const HeaderSearchOptions &HeaderOpts,
1362                               const CodeGenOptions &CGOpts,
1363                               const clang::TargetOptions &TOpts,
1364                               const LangOptions &LOpts,
1365                               std::unique_ptr<raw_pwrite_stream> OS,
1366                               std::string SampleProfile,
1367                               std::string ProfileRemapping,
1368                               BackendAction Action) {
1369   StringMap<DenseMap<GlobalValue::GUID, GlobalValueSummary *>>
1370       ModuleToDefinedGVSummaries;
1371   CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
1372 
1373   setCommandLineOpts(CGOpts);
1374 
1375   // We can simply import the values mentioned in the combined index, since
1376   // we should only invoke this using the individual indexes written out
1377   // via a WriteIndexesThinBackend.
1378   FunctionImporter::ImportMapTy ImportList;
1379   for (auto &GlobalList : *CombinedIndex) {
1380     // Ignore entries for undefined references.
1381     if (GlobalList.second.SummaryList.empty())
1382       continue;
1383 
1384     auto GUID = GlobalList.first;
1385     for (auto &Summary : GlobalList.second.SummaryList) {
1386       // Skip the summaries for the importing module. These are included to
1387       // e.g. record required linkage changes.
1388       if (Summary->modulePath() == M->getModuleIdentifier())
1389         continue;
1390       // Add an entry to provoke importing by thinBackend.
1391       ImportList[Summary->modulePath()].insert(GUID);
1392     }
1393   }
1394 
1395   std::vector<std::unique_ptr<llvm::MemoryBuffer>> OwnedImports;
1396   MapVector<llvm::StringRef, llvm::BitcodeModule> ModuleMap;
1397 
1398   for (auto &I : ImportList) {
1399     ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> MBOrErr =
1400         llvm::MemoryBuffer::getFile(I.first());
1401     if (!MBOrErr) {
1402       errs() << "Error loading imported file '" << I.first()
1403              << "': " << MBOrErr.getError().message() << "\n";
1404       return;
1405     }
1406 
1407     Expected<BitcodeModule> BMOrErr = FindThinLTOModule(**MBOrErr);
1408     if (!BMOrErr) {
1409       handleAllErrors(BMOrErr.takeError(), [&](ErrorInfoBase &EIB) {
1410         errs() << "Error loading imported file '" << I.first()
1411                << "': " << EIB.message() << '\n';
1412       });
1413       return;
1414     }
1415     ModuleMap.insert({I.first(), *BMOrErr});
1416 
1417     OwnedImports.push_back(std::move(*MBOrErr));
1418   }
1419   auto AddStream = [&](size_t Task) {
1420     return std::make_unique<lto::NativeObjectStream>(std::move(OS));
1421   };
1422   lto::Config Conf;
1423   if (CGOpts.SaveTempsFilePrefix != "") {
1424     if (Error E = Conf.addSaveTemps(CGOpts.SaveTempsFilePrefix + ".",
1425                                     /* UseInputModulePath */ false)) {
1426       handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1427         errs() << "Error setting up ThinLTO save-temps: " << EIB.message()
1428                << '\n';
1429       });
1430     }
1431   }
1432   Conf.CPU = TOpts.CPU;
1433   Conf.CodeModel = getCodeModel(CGOpts);
1434   Conf.MAttrs = TOpts.Features;
1435   Conf.RelocModel = CGOpts.RelocationModel;
1436   Conf.CGOptLevel = getCGOptLevel(CGOpts);
1437   Conf.OptLevel = CGOpts.OptimizationLevel;
1438   initTargetOptions(Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
1439   Conf.SampleProfile = std::move(SampleProfile);
1440 
1441   // Context sensitive profile.
1442   if (CGOpts.hasProfileCSIRInstr()) {
1443     Conf.RunCSIRInstr = true;
1444     Conf.CSIRProfile = std::move(CGOpts.InstrProfileOutput);
1445   } else if (CGOpts.hasProfileCSIRUse()) {
1446     Conf.RunCSIRInstr = false;
1447     Conf.CSIRProfile = std::move(CGOpts.ProfileInstrumentUsePath);
1448   }
1449 
1450   Conf.ProfileRemapping = std::move(ProfileRemapping);
1451   Conf.UseNewPM = CGOpts.ExperimentalNewPassManager;
1452   Conf.DebugPassManager = CGOpts.DebugPassManager;
1453   Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
1454   Conf.RemarksFilename = CGOpts.OptRecordFile;
1455   Conf.RemarksPasses = CGOpts.OptRecordPasses;
1456   Conf.RemarksFormat = CGOpts.OptRecordFormat;
1457   Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
1458   Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
1459   switch (Action) {
1460   case Backend_EmitNothing:
1461     Conf.PreCodeGenModuleHook = [](size_t Task, const Module &Mod) {
1462       return false;
1463     };
1464     break;
1465   case Backend_EmitLL:
1466     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1467       M->print(*OS, nullptr, CGOpts.EmitLLVMUseLists);
1468       return false;
1469     };
1470     break;
1471   case Backend_EmitBC:
1472     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1473       WriteBitcodeToFile(*M, *OS, CGOpts.EmitLLVMUseLists);
1474       return false;
1475     };
1476     break;
1477   default:
1478     Conf.CGFileType = getCodeGenFileType(Action);
1479     break;
1480   }
1481   if (Error E = thinBackend(
1482           Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
1483           ModuleToDefinedGVSummaries[M->getModuleIdentifier()], ModuleMap)) {
1484     handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1485       errs() << "Error running ThinLTO backend: " << EIB.message() << '\n';
1486     });
1487   }
1488 }
1489 
1490 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
1491                               const HeaderSearchOptions &HeaderOpts,
1492                               const CodeGenOptions &CGOpts,
1493                               const clang::TargetOptions &TOpts,
1494                               const LangOptions &LOpts,
1495                               const llvm::DataLayout &TDesc, Module *M,
1496                               BackendAction Action,
1497                               std::unique_ptr<raw_pwrite_stream> OS) {
1498 
1499   llvm::TimeTraceScope TimeScope("Backend");
1500 
1501   std::unique_ptr<llvm::Module> EmptyModule;
1502   if (!CGOpts.ThinLTOIndexFile.empty()) {
1503     // If we are performing a ThinLTO importing compile, load the function index
1504     // into memory and pass it into runThinLTOBackend, which will run the
1505     // function importer and invoke LTO passes.
1506     Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
1507         llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile,
1508                                            /*IgnoreEmptyThinLTOIndexFile*/true);
1509     if (!IndexOrErr) {
1510       logAllUnhandledErrors(IndexOrErr.takeError(), errs(),
1511                             "Error loading index file '" +
1512                             CGOpts.ThinLTOIndexFile + "': ");
1513       return;
1514     }
1515     std::unique_ptr<ModuleSummaryIndex> CombinedIndex = std::move(*IndexOrErr);
1516     // A null CombinedIndex means we should skip ThinLTO compilation
1517     // (LLVM will optionally ignore empty index files, returning null instead
1518     // of an error).
1519     if (CombinedIndex) {
1520       if (!CombinedIndex->skipModuleByDistributedBackend()) {
1521         runThinLTOBackend(CombinedIndex.get(), M, HeaderOpts, CGOpts, TOpts,
1522                           LOpts, std::move(OS), CGOpts.SampleProfileFile,
1523                           CGOpts.ProfileRemappingFile, Action);
1524         return;
1525       }
1526       // Distributed indexing detected that nothing from the module is needed
1527       // for the final linking. So we can skip the compilation. We sill need to
1528       // output an empty object file to make sure that a linker does not fail
1529       // trying to read it. Also for some features, like CFI, we must skip
1530       // the compilation as CombinedIndex does not contain all required
1531       // information.
1532       EmptyModule = std::make_unique<llvm::Module>("empty", M->getContext());
1533       EmptyModule->setTargetTriple(M->getTargetTriple());
1534       M = EmptyModule.get();
1535     }
1536   }
1537 
1538   EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
1539 
1540   if (CGOpts.ExperimentalNewPassManager)
1541     AsmHelper.EmitAssemblyWithNewPassManager(Action, std::move(OS));
1542   else
1543     AsmHelper.EmitAssembly(Action, std::move(OS));
1544 
1545   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
1546   // DataLayout.
1547   if (AsmHelper.TM) {
1548     std::string DLDesc = M->getDataLayout().getStringRepresentation();
1549     if (DLDesc != TDesc.getStringRepresentation()) {
1550       unsigned DiagID = Diags.getCustomDiagID(
1551           DiagnosticsEngine::Error, "backend data layout '%0' does not match "
1552                                     "expected target description '%1'");
1553       Diags.Report(DiagID) << DLDesc << TDesc.getStringRepresentation();
1554     }
1555   }
1556 }
1557 
1558 // With -fembed-bitcode, save a copy of the llvm IR as data in the
1559 // __LLVM,__bitcode section.
1560 void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
1561                          llvm::MemoryBufferRef Buf) {
1562   if (CGOpts.getEmbedBitcode() == CodeGenOptions::Embed_Off)
1563     return;
1564   llvm::EmbedBitcodeInModule(
1565       *M, Buf, CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Marker,
1566       CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Bitcode,
1567       &CGOpts.CmdArgs);
1568 }
1569