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/Support/BuryPointer.h"
41 #include "llvm/Support/CommandLine.h"
42 #include "llvm/Support/MemoryBuffer.h"
43 #include "llvm/Support/PrettyStackTrace.h"
44 #include "llvm/Support/TargetRegistry.h"
45 #include "llvm/Support/TimeProfiler.h"
46 #include "llvm/Support/Timer.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include "llvm/Target/TargetMachine.h"
49 #include "llvm/Target/TargetOptions.h"
50 #include "llvm/Transforms/Coroutines.h"
51 #include "llvm/Transforms/IPO.h"
52 #include "llvm/Transforms/IPO/AlwaysInliner.h"
53 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
54 #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
55 #include "llvm/Transforms/InstCombine/InstCombine.h"
56 #include "llvm/Transforms/Instrumentation.h"
57 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
58 #include "llvm/Transforms/Instrumentation/BoundsChecking.h"
59 #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
60 #include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
61 #include "llvm/Transforms/Instrumentation/InstrProfiling.h"
62 #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
63 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
64 #include "llvm/Transforms/ObjCARC.h"
65 #include "llvm/Transforms/Scalar.h"
66 #include "llvm/Transforms/Scalar/GVN.h"
67 #include "llvm/Transforms/Utils.h"
68 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
69 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
70 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
71 #include "llvm/Transforms/Utils/SymbolRewriter.h"
72 #include <memory>
73 using namespace clang;
74 using namespace llvm;
75 
76 namespace {
77 
78 // Default filename used for profile generation.
79 static constexpr StringLiteral DefaultProfileGenName = "default_%m.profraw";
80 
81 class EmitAssemblyHelper {
82   DiagnosticsEngine &Diags;
83   const HeaderSearchOptions &HSOpts;
84   const CodeGenOptions &CodeGenOpts;
85   const clang::TargetOptions &TargetOpts;
86   const LangOptions &LangOpts;
87   Module *TheModule;
88 
89   Timer CodeGenerationTime;
90 
91   std::unique_ptr<raw_pwrite_stream> OS;
92 
93   TargetIRAnalysis getTargetIRAnalysis() const {
94     if (TM)
95       return TM->getTargetIRAnalysis();
96 
97     return TargetIRAnalysis();
98   }
99 
100   void CreatePasses(legacy::PassManager &MPM, legacy::FunctionPassManager &FPM);
101 
102   /// Generates the TargetMachine.
103   /// Leaves TM unchanged if it is unable to create the target machine.
104   /// Some of our clang tests specify triples which are not built
105   /// into clang. This is okay because these tests check the generated
106   /// IR, and they require DataLayout which depends on the triple.
107   /// In this case, we allow this method to fail and not report an error.
108   /// When MustCreateTM is used, we print an error if we are unable to load
109   /// the requested target.
110   void CreateTargetMachine(bool MustCreateTM);
111 
112   /// Add passes necessary to emit assembly or LLVM IR.
113   ///
114   /// \return True on success.
115   bool AddEmitPasses(legacy::PassManager &CodeGenPasses, BackendAction Action,
116                      raw_pwrite_stream &OS, raw_pwrite_stream *DwoOS);
117 
118   std::unique_ptr<llvm::ToolOutputFile> openOutputFile(StringRef Path) {
119     std::error_code EC;
120     auto F = llvm::make_unique<llvm::ToolOutputFile>(Path, EC,
121                                                      llvm::sys::fs::F_None);
122     if (EC) {
123       Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
124       F.reset();
125     }
126     return F;
127   }
128 
129 public:
130   EmitAssemblyHelper(DiagnosticsEngine &_Diags,
131                      const HeaderSearchOptions &HeaderSearchOpts,
132                      const CodeGenOptions &CGOpts,
133                      const clang::TargetOptions &TOpts,
134                      const LangOptions &LOpts, Module *M)
135       : Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
136         TargetOpts(TOpts), LangOpts(LOpts), TheModule(M),
137         CodeGenerationTime("codegen", "Code Generation Time") {}
138 
139   ~EmitAssemblyHelper() {
140     if (CodeGenOpts.DisableFree)
141       BuryPointer(std::move(TM));
142   }
143 
144   std::unique_ptr<TargetMachine> TM;
145 
146   void EmitAssembly(BackendAction Action,
147                     std::unique_ptr<raw_pwrite_stream> OS);
148 
149   void EmitAssemblyWithNewPassManager(BackendAction Action,
150                                       std::unique_ptr<raw_pwrite_stream> OS);
151 };
152 
153 // We need this wrapper to access LangOpts and CGOpts from extension functions
154 // that we add to the PassManagerBuilder.
155 class PassManagerBuilderWrapper : public PassManagerBuilder {
156 public:
157   PassManagerBuilderWrapper(const Triple &TargetTriple,
158                             const CodeGenOptions &CGOpts,
159                             const LangOptions &LangOpts)
160       : PassManagerBuilder(), TargetTriple(TargetTriple), CGOpts(CGOpts),
161         LangOpts(LangOpts) {}
162   const Triple &getTargetTriple() const { return TargetTriple; }
163   const CodeGenOptions &getCGOpts() const { return CGOpts; }
164   const LangOptions &getLangOpts() const { return LangOpts; }
165 
166 private:
167   const Triple &TargetTriple;
168   const CodeGenOptions &CGOpts;
169   const LangOptions &LangOpts;
170 };
171 }
172 
173 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
174   if (Builder.OptLevel > 0)
175     PM.add(createObjCARCAPElimPass());
176 }
177 
178 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
179   if (Builder.OptLevel > 0)
180     PM.add(createObjCARCExpandPass());
181 }
182 
183 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
184   if (Builder.OptLevel > 0)
185     PM.add(createObjCARCOptPass());
186 }
187 
188 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
189                                      legacy::PassManagerBase &PM) {
190   PM.add(createAddDiscriminatorsPass());
191 }
192 
193 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
194                                   legacy::PassManagerBase &PM) {
195   PM.add(createBoundsCheckingLegacyPass());
196 }
197 
198 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
199                                      legacy::PassManagerBase &PM) {
200   const PassManagerBuilderWrapper &BuilderWrapper =
201       static_cast<const PassManagerBuilderWrapper&>(Builder);
202   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
203   SanitizerCoverageOptions Opts;
204   Opts.CoverageType =
205       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
206   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
207   Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
208   Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
209   Opts.TraceDiv = CGOpts.SanitizeCoverageTraceDiv;
210   Opts.TraceGep = CGOpts.SanitizeCoverageTraceGep;
211   Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
212   Opts.TracePC = CGOpts.SanitizeCoverageTracePC;
213   Opts.TracePCGuard = CGOpts.SanitizeCoverageTracePCGuard;
214   Opts.NoPrune = CGOpts.SanitizeCoverageNoPrune;
215   Opts.Inline8bitCounters = CGOpts.SanitizeCoverageInline8bitCounters;
216   Opts.PCTable = CGOpts.SanitizeCoveragePCTable;
217   Opts.StackDepth = CGOpts.SanitizeCoverageStackDepth;
218   PM.add(createSanitizerCoverageModulePass(Opts));
219 }
220 
221 // Check if ASan should use GC-friendly instrumentation for globals.
222 // First of all, there is no point if -fdata-sections is off (expect for MachO,
223 // where this is not a factor). Also, on ELF this feature requires an assembler
224 // extension that only works with -integrated-as at the moment.
225 static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
226   if (!CGOpts.SanitizeAddressGlobalsDeadStripping)
227     return false;
228   switch (T.getObjectFormat()) {
229   case Triple::MachO:
230   case Triple::COFF:
231     return true;
232   case Triple::ELF:
233     return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
234   default:
235     return false;
236   }
237 }
238 
239 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
240                                       legacy::PassManagerBase &PM) {
241   const PassManagerBuilderWrapper &BuilderWrapper =
242       static_cast<const PassManagerBuilderWrapper&>(Builder);
243   const Triple &T = BuilderWrapper.getTargetTriple();
244   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
245   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
246   bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
247   bool UseOdrIndicator = CGOpts.SanitizeAddressUseOdrIndicator;
248   bool UseGlobalsGC = asanUseGlobalsGC(T, CGOpts);
249   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
250                                             UseAfterScope));
251   PM.add(createModuleAddressSanitizerLegacyPassPass(
252       /*CompileKernel*/ false, Recover, UseGlobalsGC, UseOdrIndicator));
253 }
254 
255 static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
256                                             legacy::PassManagerBase &PM) {
257   PM.add(createAddressSanitizerFunctionPass(
258       /*CompileKernel*/ true, /*Recover*/ true, /*UseAfterScope*/ false));
259   PM.add(createModuleAddressSanitizerLegacyPassPass(
260       /*CompileKernel*/ true, /*Recover*/ true, /*UseGlobalsGC*/ true,
261       /*UseOdrIndicator*/ false));
262 }
263 
264 static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
265                                             legacy::PassManagerBase &PM) {
266   const PassManagerBuilderWrapper &BuilderWrapper =
267       static_cast<const PassManagerBuilderWrapper &>(Builder);
268   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
269   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
270   PM.add(
271       createHWAddressSanitizerLegacyPassPass(/*CompileKernel*/ false, Recover));
272 }
273 
274 static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
275                                             legacy::PassManagerBase &PM) {
276   PM.add(createHWAddressSanitizerLegacyPassPass(
277       /*CompileKernel*/ true, /*Recover*/ true));
278 }
279 
280 static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
281                                              legacy::PassManagerBase &PM,
282                                              bool CompileKernel) {
283   const PassManagerBuilderWrapper &BuilderWrapper =
284       static_cast<const PassManagerBuilderWrapper&>(Builder);
285   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
286   int TrackOrigins = CGOpts.SanitizeMemoryTrackOrigins;
287   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Memory);
288   PM.add(createMemorySanitizerLegacyPassPass(
289       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
290 
291   // MemorySanitizer inserts complex instrumentation that mostly follows
292   // the logic of the original code, but operates on "shadow" values.
293   // It can benefit from re-running some general purpose optimization passes.
294   if (Builder.OptLevel > 0) {
295     PM.add(createEarlyCSEPass());
296     PM.add(createReassociatePass());
297     PM.add(createLICMPass());
298     PM.add(createGVNPass());
299     PM.add(createInstructionCombiningPass());
300     PM.add(createDeadStoreEliminationPass());
301   }
302 }
303 
304 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
305                                    legacy::PassManagerBase &PM) {
306   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ false);
307 }
308 
309 static void addKernelMemorySanitizerPass(const PassManagerBuilder &Builder,
310                                          legacy::PassManagerBase &PM) {
311   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ true);
312 }
313 
314 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
315                                    legacy::PassManagerBase &PM) {
316   PM.add(createThreadSanitizerLegacyPassPass());
317 }
318 
319 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
320                                      legacy::PassManagerBase &PM) {
321   const PassManagerBuilderWrapper &BuilderWrapper =
322       static_cast<const PassManagerBuilderWrapper&>(Builder);
323   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
324   PM.add(createDataFlowSanitizerPass(LangOpts.SanitizerBlacklistFiles));
325 }
326 
327 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
328                                          const CodeGenOptions &CodeGenOpts) {
329   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
330   if (!CodeGenOpts.SimplifyLibCalls)
331     TLII->disableAllFunctions();
332   else {
333     // Disable individual libc/libm calls in TargetLibraryInfo.
334     LibFunc F;
335     for (auto &FuncName : CodeGenOpts.getNoBuiltinFuncs())
336       if (TLII->getLibFunc(FuncName, F))
337         TLII->setUnavailable(F);
338   }
339 
340   switch (CodeGenOpts.getVecLib()) {
341   case CodeGenOptions::Accelerate:
342     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
343     break;
344   case CodeGenOptions::MASSV:
345     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::MASSV);
346     break;
347   case CodeGenOptions::SVML:
348     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::SVML);
349     break;
350   default:
351     break;
352   }
353   return TLII;
354 }
355 
356 static void addSymbolRewriterPass(const CodeGenOptions &Opts,
357                                   legacy::PassManager *MPM) {
358   llvm::SymbolRewriter::RewriteDescriptorList DL;
359 
360   llvm::SymbolRewriter::RewriteMapParser MapParser;
361   for (const auto &MapFile : Opts.RewriteMapFiles)
362     MapParser.parse(MapFile, &DL);
363 
364   MPM->add(createRewriteSymbolsPass(DL));
365 }
366 
367 static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
368   switch (CodeGenOpts.OptimizationLevel) {
369   default:
370     llvm_unreachable("Invalid optimization level!");
371   case 0:
372     return CodeGenOpt::None;
373   case 1:
374     return CodeGenOpt::Less;
375   case 2:
376     return CodeGenOpt::Default; // O2/Os/Oz
377   case 3:
378     return CodeGenOpt::Aggressive;
379   }
380 }
381 
382 static Optional<llvm::CodeModel::Model>
383 getCodeModel(const CodeGenOptions &CodeGenOpts) {
384   unsigned CodeModel = llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
385                            .Case("tiny", llvm::CodeModel::Tiny)
386                            .Case("small", llvm::CodeModel::Small)
387                            .Case("kernel", llvm::CodeModel::Kernel)
388                            .Case("medium", llvm::CodeModel::Medium)
389                            .Case("large", llvm::CodeModel::Large)
390                            .Case("default", ~1u)
391                            .Default(~0u);
392   assert(CodeModel != ~0u && "invalid code model!");
393   if (CodeModel == ~1u)
394     return None;
395   return static_cast<llvm::CodeModel::Model>(CodeModel);
396 }
397 
398 static TargetMachine::CodeGenFileType getCodeGenFileType(BackendAction Action) {
399   if (Action == Backend_EmitObj)
400     return TargetMachine::CGFT_ObjectFile;
401   else if (Action == Backend_EmitMCNull)
402     return TargetMachine::CGFT_Null;
403   else {
404     assert(Action == Backend_EmitAssembly && "Invalid action!");
405     return TargetMachine::CGFT_AssemblyFile;
406   }
407 }
408 
409 static void initTargetOptions(llvm::TargetOptions &Options,
410                               const CodeGenOptions &CodeGenOpts,
411                               const clang::TargetOptions &TargetOpts,
412                               const LangOptions &LangOpts,
413                               const HeaderSearchOptions &HSOpts) {
414   Options.ThreadModel =
415       llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
416           .Case("posix", llvm::ThreadModel::POSIX)
417           .Case("single", llvm::ThreadModel::Single);
418 
419   // Set float ABI type.
420   assert((CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp" ||
421           CodeGenOpts.FloatABI == "hard" || CodeGenOpts.FloatABI.empty()) &&
422          "Invalid Floating Point ABI!");
423   Options.FloatABIType =
424       llvm::StringSwitch<llvm::FloatABI::ABIType>(CodeGenOpts.FloatABI)
425           .Case("soft", llvm::FloatABI::Soft)
426           .Case("softfp", llvm::FloatABI::Soft)
427           .Case("hard", llvm::FloatABI::Hard)
428           .Default(llvm::FloatABI::Default);
429 
430   // Set FP fusion mode.
431   switch (LangOpts.getDefaultFPContractMode()) {
432   case LangOptions::FPC_Off:
433     // Preserve any contraction performed by the front-end.  (Strict performs
434     // splitting of the muladd intrinsic in the backend.)
435     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
436     break;
437   case LangOptions::FPC_On:
438     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
439     break;
440   case LangOptions::FPC_Fast:
441     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
442     break;
443   }
444 
445   Options.UseInitArray = CodeGenOpts.UseInitArray;
446   Options.DisableIntegratedAS = CodeGenOpts.DisableIntegratedAS;
447   Options.CompressDebugSections = CodeGenOpts.getCompressDebugSections();
448   Options.RelaxELFRelocations = CodeGenOpts.RelaxELFRelocations;
449 
450   // Set EABI version.
451   Options.EABIVersion = TargetOpts.EABIVersion;
452 
453   if (LangOpts.SjLjExceptions)
454     Options.ExceptionModel = llvm::ExceptionHandling::SjLj;
455   if (LangOpts.SEHExceptions)
456     Options.ExceptionModel = llvm::ExceptionHandling::WinEH;
457   if (LangOpts.DWARFExceptions)
458     Options.ExceptionModel = llvm::ExceptionHandling::DwarfCFI;
459 
460   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
461   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
462   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
463   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
464   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
465   Options.FunctionSections = CodeGenOpts.FunctionSections;
466   Options.DataSections = CodeGenOpts.DataSections;
467   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
468   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
469   Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
470   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
471   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
472   Options.EmitAddrsig = CodeGenOpts.Addrsig;
473   Options.EnableDebugEntryValues = CodeGenOpts.EnableDebugEntryValues;
474 
475   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
476   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
477   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
478   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
479   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
480   Options.MCOptions.MCIncrementalLinkerCompatible =
481       CodeGenOpts.IncrementalLinkerCompatible;
482   Options.MCOptions.MCPIECopyRelocations = CodeGenOpts.PIECopyRelocations;
483   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
484   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
485   Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
486   Options.MCOptions.ABIName = TargetOpts.ABI;
487   for (const auto &Entry : HSOpts.UserEntries)
488     if (!Entry.IsFramework &&
489         (Entry.Group == frontend::IncludeDirGroup::Quoted ||
490          Entry.Group == frontend::IncludeDirGroup::Angled ||
491          Entry.Group == frontend::IncludeDirGroup::System))
492       Options.MCOptions.IASSearchPaths.push_back(
493           Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);
494 }
495 static Optional<GCOVOptions> getGCOVOptions(const CodeGenOptions &CodeGenOpts) {
496   if (CodeGenOpts.DisableGCov)
497     return None;
498   if (!CodeGenOpts.EmitGcovArcs && !CodeGenOpts.EmitGcovNotes)
499     return None;
500   // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
501   // LLVM's -default-gcov-version flag is set to something invalid.
502   GCOVOptions Options;
503   Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
504   Options.EmitData = CodeGenOpts.EmitGcovArcs;
505   llvm::copy(CodeGenOpts.CoverageVersion, std::begin(Options.Version));
506   Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
507   Options.NoRedZone = CodeGenOpts.DisableRedZone;
508   Options.FunctionNamesInData = !CodeGenOpts.CoverageNoFunctionNamesInData;
509   Options.Filter = CodeGenOpts.ProfileFilterFiles;
510   Options.Exclude = CodeGenOpts.ProfileExcludeFiles;
511   Options.ExitBlockBeforeBody = CodeGenOpts.CoverageExitBlockBeforeBody;
512   return Options;
513 }
514 
515 static Optional<InstrProfOptions>
516 getInstrProfOptions(const CodeGenOptions &CodeGenOpts,
517                     const LangOptions &LangOpts) {
518   if (!CodeGenOpts.hasProfileClangInstr())
519     return None;
520   InstrProfOptions Options;
521   Options.NoRedZone = CodeGenOpts.DisableRedZone;
522   Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
523 
524   // TODO: Surface the option to emit atomic profile counter increments at
525   // the driver level.
526   Options.Atomic = LangOpts.Sanitize.has(SanitizerKind::Thread);
527   return Options;
528 }
529 
530 void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
531                                       legacy::FunctionPassManager &FPM) {
532   // Handle disabling of all LLVM passes, where we want to preserve the
533   // internal module before any optimization.
534   if (CodeGenOpts.DisableLLVMPasses)
535     return;
536 
537   // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
538   // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
539   // are inserted before PMBuilder ones - they'd get the default-constructed
540   // TLI with an unknown target otherwise.
541   Triple TargetTriple(TheModule->getTargetTriple());
542   std::unique_ptr<TargetLibraryInfoImpl> TLII(
543       createTLII(TargetTriple, CodeGenOpts));
544 
545   PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
546 
547   // At O0 and O1 we only run the always inliner which is more efficient. At
548   // higher optimization levels we run the normal inliner.
549   if (CodeGenOpts.OptimizationLevel <= 1) {
550     bool InsertLifetimeIntrinsics = (CodeGenOpts.OptimizationLevel != 0 &&
551                                      !CodeGenOpts.DisableLifetimeMarkers);
552     PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
553   } else {
554     // We do not want to inline hot callsites for SamplePGO module-summary build
555     // because profile annotation will happen again in ThinLTO backend, and we
556     // want the IR of the hot path to match the profile.
557     PMBuilder.Inliner = createFunctionInliningPass(
558         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
559         (!CodeGenOpts.SampleProfileFile.empty() &&
560          CodeGenOpts.PrepareForThinLTO));
561   }
562 
563   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
564   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
565   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
566   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
567 
568   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
569   // Loop interleaving in the loop vectorizer has historically been set to be
570   // enabled when loop unrolling is enabled.
571   PMBuilder.LoopsInterleaved = CodeGenOpts.UnrollLoops;
572   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
573   PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
574   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
575   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
576 
577   MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
578 
579   if (TM)
580     TM->adjustPassManager(PMBuilder);
581 
582   if (CodeGenOpts.DebugInfoForProfiling ||
583       !CodeGenOpts.SampleProfileFile.empty())
584     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
585                            addAddDiscriminatorsPass);
586 
587   // In ObjC ARC mode, add the main ARC optimization passes.
588   if (LangOpts.ObjCAutoRefCount) {
589     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
590                            addObjCARCExpandPass);
591     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
592                            addObjCARCAPElimPass);
593     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
594                            addObjCARCOptPass);
595   }
596 
597   if (LangOpts.Coroutines)
598     addCoroutinePassesToExtensionPoints(PMBuilder);
599 
600   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
601     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
602                            addBoundsCheckingPass);
603     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
604                            addBoundsCheckingPass);
605   }
606 
607   if (CodeGenOpts.SanitizeCoverageType ||
608       CodeGenOpts.SanitizeCoverageIndirectCalls ||
609       CodeGenOpts.SanitizeCoverageTraceCmp) {
610     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
611                            addSanitizerCoveragePass);
612     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
613                            addSanitizerCoveragePass);
614   }
615 
616   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
617     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
618                            addAddressSanitizerPasses);
619     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
620                            addAddressSanitizerPasses);
621   }
622 
623   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
624     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
625                            addKernelAddressSanitizerPasses);
626     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
627                            addKernelAddressSanitizerPasses);
628   }
629 
630   if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
631     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
632                            addHWAddressSanitizerPasses);
633     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
634                            addHWAddressSanitizerPasses);
635   }
636 
637   if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
638     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
639                            addKernelHWAddressSanitizerPasses);
640     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
641                            addKernelHWAddressSanitizerPasses);
642   }
643 
644   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
645     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
646                            addMemorySanitizerPass);
647     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
648                            addMemorySanitizerPass);
649   }
650 
651   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
652     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
653                            addKernelMemorySanitizerPass);
654     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
655                            addKernelMemorySanitizerPass);
656   }
657 
658   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
659     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
660                            addThreadSanitizerPass);
661     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
662                            addThreadSanitizerPass);
663   }
664 
665   if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
666     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
667                            addDataFlowSanitizerPass);
668     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
669                            addDataFlowSanitizerPass);
670   }
671 
672   // Set up the per-function pass manager.
673   FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
674   if (CodeGenOpts.VerifyModule)
675     FPM.add(createVerifierPass());
676 
677   // Set up the per-module pass manager.
678   if (!CodeGenOpts.RewriteMapFiles.empty())
679     addSymbolRewriterPass(CodeGenOpts, &MPM);
680 
681   if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts)) {
682     MPM.add(createGCOVProfilerPass(*Options));
683     if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
684       MPM.add(createStripSymbolsPass(true));
685   }
686 
687   if (Optional<InstrProfOptions> Options =
688           getInstrProfOptions(CodeGenOpts, LangOpts))
689     MPM.add(createInstrProfilingLegacyPass(*Options, false));
690 
691   bool hasIRInstr = false;
692   if (CodeGenOpts.hasProfileIRInstr()) {
693     PMBuilder.EnablePGOInstrGen = true;
694     hasIRInstr = true;
695   }
696   if (CodeGenOpts.hasProfileCSIRInstr()) {
697     assert(!CodeGenOpts.hasProfileCSIRUse() &&
698            "Cannot have both CSProfileUse pass and CSProfileGen pass at the "
699            "same time");
700     assert(!hasIRInstr &&
701            "Cannot have both ProfileGen pass and CSProfileGen pass at the "
702            "same time");
703     PMBuilder.EnablePGOCSInstrGen = true;
704     hasIRInstr = true;
705   }
706   if (hasIRInstr) {
707     if (!CodeGenOpts.InstrProfileOutput.empty())
708       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
709     else
710       PMBuilder.PGOInstrGen = DefaultProfileGenName;
711   }
712   if (CodeGenOpts.hasProfileIRUse()) {
713     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
714     PMBuilder.EnablePGOCSInstrUse = CodeGenOpts.hasProfileCSIRUse();
715   }
716 
717   if (!CodeGenOpts.SampleProfileFile.empty())
718     PMBuilder.PGOSampleUse = CodeGenOpts.SampleProfileFile;
719 
720   PMBuilder.populateFunctionPassManager(FPM);
721   PMBuilder.populateModulePassManager(MPM);
722 }
723 
724 static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) {
725   SmallVector<const char *, 16> BackendArgs;
726   BackendArgs.push_back("clang"); // Fake program name.
727   if (!CodeGenOpts.DebugPass.empty()) {
728     BackendArgs.push_back("-debug-pass");
729     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
730   }
731   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
732     BackendArgs.push_back("-limit-float-precision");
733     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
734   }
735   BackendArgs.push_back(nullptr);
736   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
737                                     BackendArgs.data());
738 }
739 
740 void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
741   // Create the TargetMachine for generating code.
742   std::string Error;
743   std::string Triple = TheModule->getTargetTriple();
744   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
745   if (!TheTarget) {
746     if (MustCreateTM)
747       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
748     return;
749   }
750 
751   Optional<llvm::CodeModel::Model> CM = getCodeModel(CodeGenOpts);
752   std::string FeaturesStr =
753       llvm::join(TargetOpts.Features.begin(), TargetOpts.Features.end(), ",");
754   llvm::Reloc::Model RM = CodeGenOpts.RelocationModel;
755   CodeGenOpt::Level OptLevel = getCGOptLevel(CodeGenOpts);
756 
757   llvm::TargetOptions Options;
758   initTargetOptions(Options, CodeGenOpts, TargetOpts, LangOpts, HSOpts);
759   TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
760                                           Options, RM, CM, OptLevel));
761 }
762 
763 bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
764                                        BackendAction Action,
765                                        raw_pwrite_stream &OS,
766                                        raw_pwrite_stream *DwoOS) {
767   // Add LibraryInfo.
768   llvm::Triple TargetTriple(TheModule->getTargetTriple());
769   std::unique_ptr<TargetLibraryInfoImpl> TLII(
770       createTLII(TargetTriple, CodeGenOpts));
771   CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
772 
773   // Normal mode, emit a .s or .o file by running the code generator. Note,
774   // this also adds codegenerator level optimization passes.
775   TargetMachine::CodeGenFileType CGFT = getCodeGenFileType(Action);
776 
777   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
778   // "codegen" passes so that it isn't run multiple times when there is
779   // inlining happening.
780   if (CodeGenOpts.OptimizationLevel > 0)
781     CodeGenPasses.add(createObjCARCContractPass());
782 
783   if (TM->addPassesToEmitFile(CodeGenPasses, OS, DwoOS, CGFT,
784                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
785     Diags.Report(diag::err_fe_unable_to_interface_with_target);
786     return false;
787   }
788 
789   return true;
790 }
791 
792 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
793                                       std::unique_ptr<raw_pwrite_stream> OS) {
794   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
795 
796   setCommandLineOpts(CodeGenOpts);
797 
798   bool UsesCodeGen = (Action != Backend_EmitNothing &&
799                       Action != Backend_EmitBC &&
800                       Action != Backend_EmitLL);
801   CreateTargetMachine(UsesCodeGen);
802 
803   if (UsesCodeGen && !TM)
804     return;
805   if (TM)
806     TheModule->setDataLayout(TM->createDataLayout());
807 
808   legacy::PassManager PerModulePasses;
809   PerModulePasses.add(
810       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
811 
812   legacy::FunctionPassManager PerFunctionPasses(TheModule);
813   PerFunctionPasses.add(
814       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
815 
816   CreatePasses(PerModulePasses, PerFunctionPasses);
817 
818   legacy::PassManager CodeGenPasses;
819   CodeGenPasses.add(
820       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
821 
822   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
823 
824   switch (Action) {
825   case Backend_EmitNothing:
826     break;
827 
828   case Backend_EmitBC:
829     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
830       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
831         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
832         if (!ThinLinkOS)
833           return;
834       }
835       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
836                                CodeGenOpts.EnableSplitLTOUnit);
837       PerModulePasses.add(createWriteThinLTOBitcodePass(
838           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
839     } else {
840       // Emit a module summary by default for Regular LTO except for ld64
841       // targets
842       bool EmitLTOSummary =
843           (CodeGenOpts.PrepareForLTO &&
844            !CodeGenOpts.DisableLLVMPasses &&
845            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
846                llvm::Triple::Apple);
847       if (EmitLTOSummary) {
848         if (!TheModule->getModuleFlag("ThinLTO"))
849           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
850         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
851                                  CodeGenOpts.EnableSplitLTOUnit);
852       }
853 
854       PerModulePasses.add(createBitcodeWriterPass(
855           *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
856     }
857     break;
858 
859   case Backend_EmitLL:
860     PerModulePasses.add(
861         createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
862     break;
863 
864   default:
865     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
866       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
867       if (!DwoOS)
868         return;
869     }
870     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
871                        DwoOS ? &DwoOS->os() : nullptr))
872       return;
873   }
874 
875   // Before executing passes, print the final values of the LLVM options.
876   cl::PrintOptionValues();
877 
878   // Run passes. For now we do all passes at once, but eventually we
879   // would like to have the option of streaming code generation.
880 
881   {
882     PrettyStackTraceString CrashInfo("Per-function optimization");
883 
884     PerFunctionPasses.doInitialization();
885     for (Function &F : *TheModule)
886       if (!F.isDeclaration())
887         PerFunctionPasses.run(F);
888     PerFunctionPasses.doFinalization();
889   }
890 
891   {
892     PrettyStackTraceString CrashInfo("Per-module optimization passes");
893     PerModulePasses.run(*TheModule);
894   }
895 
896   {
897     PrettyStackTraceString CrashInfo("Code generation");
898     CodeGenPasses.run(*TheModule);
899   }
900 
901   if (ThinLinkOS)
902     ThinLinkOS->keep();
903   if (DwoOS)
904     DwoOS->keep();
905 }
906 
907 static PassBuilder::OptimizationLevel mapToLevel(const CodeGenOptions &Opts) {
908   switch (Opts.OptimizationLevel) {
909   default:
910     llvm_unreachable("Invalid optimization level!");
911 
912   case 1:
913     return PassBuilder::O1;
914 
915   case 2:
916     switch (Opts.OptimizeSize) {
917     default:
918       llvm_unreachable("Invalid optimization level for size!");
919 
920     case 0:
921       return PassBuilder::O2;
922 
923     case 1:
924       return PassBuilder::Os;
925 
926     case 2:
927       return PassBuilder::Oz;
928     }
929 
930   case 3:
931     return PassBuilder::O3;
932   }
933 }
934 
935 static void addSanitizersAtO0(ModulePassManager &MPM,
936                               const Triple &TargetTriple,
937                               const LangOptions &LangOpts,
938                               const CodeGenOptions &CodeGenOpts) {
939   auto ASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
940     MPM.addPass(RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
941     bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
942     MPM.addPass(createModuleToFunctionPassAdaptor(AddressSanitizerPass(
943         CompileKernel, Recover, CodeGenOpts.SanitizeAddressUseAfterScope)));
944     bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
945     MPM.addPass(
946         ModuleAddressSanitizerPass(CompileKernel, Recover, ModuleUseAfterScope,
947                                    CodeGenOpts.SanitizeAddressUseOdrIndicator));
948   };
949 
950   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
951     ASanPass(SanitizerKind::Address, /*CompileKernel=*/false);
952   }
953 
954   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
955     ASanPass(SanitizerKind::KernelAddress, /*CompileKernel=*/true);
956   }
957 
958   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
959     MPM.addPass(createModuleToFunctionPassAdaptor(MemorySanitizerPass({})));
960   }
961 
962   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
963     MPM.addPass(createModuleToFunctionPassAdaptor(
964         MemorySanitizerPass({0, false, /*Kernel=*/true})));
965   }
966 
967   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
968     MPM.addPass(createModuleToFunctionPassAdaptor(ThreadSanitizerPass()));
969   }
970 
971   if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
972     bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
973     MPM.addPass(createModuleToFunctionPassAdaptor(
974         HWAddressSanitizerPass(/*CompileKernel=*/false, Recover)));
975   }
976 
977   if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
978     MPM.addPass(createModuleToFunctionPassAdaptor(
979         HWAddressSanitizerPass(/*CompileKernel=*/true, /*Recover=*/true)));
980   }
981 }
982 
983 /// A clean version of `EmitAssembly` that uses the new pass manager.
984 ///
985 /// Not all features are currently supported in this system, but where
986 /// necessary it falls back to the legacy pass manager to at least provide
987 /// basic functionality.
988 ///
989 /// This API is planned to have its functionality finished and then to replace
990 /// `EmitAssembly` at some point in the future when the default switches.
991 void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
992     BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
993   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
994   setCommandLineOpts(CodeGenOpts);
995 
996   bool RequiresCodeGen = (Action != Backend_EmitNothing &&
997                           Action != Backend_EmitBC &&
998                           Action != Backend_EmitLL);
999   CreateTargetMachine(RequiresCodeGen);
1000 
1001   if (RequiresCodeGen && !TM)
1002     return;
1003   if (TM)
1004     TheModule->setDataLayout(TM->createDataLayout());
1005 
1006   Optional<PGOOptions> PGOOpt;
1007 
1008   if (CodeGenOpts.hasProfileIRInstr())
1009     // -fprofile-generate.
1010     PGOOpt = PGOOptions(CodeGenOpts.InstrProfileOutput.empty()
1011                             ? DefaultProfileGenName
1012                             : CodeGenOpts.InstrProfileOutput,
1013                         "", "", PGOOptions::IRInstr, PGOOptions::NoCSAction,
1014                         CodeGenOpts.DebugInfoForProfiling);
1015   else if (CodeGenOpts.hasProfileIRUse()) {
1016     // -fprofile-use.
1017     auto CSAction = CodeGenOpts.hasProfileCSIRUse() ? PGOOptions::CSIRUse
1018                                                     : PGOOptions::NoCSAction;
1019     PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "",
1020                         CodeGenOpts.ProfileRemappingFile, PGOOptions::IRUse,
1021                         CSAction, CodeGenOpts.DebugInfoForProfiling);
1022   } else if (!CodeGenOpts.SampleProfileFile.empty())
1023     // -fprofile-sample-use
1024     PGOOpt =
1025         PGOOptions(CodeGenOpts.SampleProfileFile, "",
1026                    CodeGenOpts.ProfileRemappingFile, PGOOptions::SampleUse,
1027                    PGOOptions::NoCSAction, CodeGenOpts.DebugInfoForProfiling);
1028   else if (CodeGenOpts.DebugInfoForProfiling)
1029     // -fdebug-info-for-profiling
1030     PGOOpt = PGOOptions("", "", "", PGOOptions::NoAction,
1031                         PGOOptions::NoCSAction, true);
1032 
1033   // Check to see if we want to generate a CS profile.
1034   if (CodeGenOpts.hasProfileCSIRInstr()) {
1035     assert(!CodeGenOpts.hasProfileCSIRUse() &&
1036            "Cannot have both CSProfileUse pass and CSProfileGen pass at "
1037            "the same time");
1038     if (PGOOpt.hasValue()) {
1039       assert(PGOOpt->Action != PGOOptions::IRInstr &&
1040              PGOOpt->Action != PGOOptions::SampleUse &&
1041              "Cannot run CSProfileGen pass with ProfileGen or SampleUse "
1042              " pass");
1043       PGOOpt->CSProfileGenFile = CodeGenOpts.InstrProfileOutput.empty()
1044                                      ? DefaultProfileGenName
1045                                      : CodeGenOpts.InstrProfileOutput;
1046       PGOOpt->CSAction = PGOOptions::CSIRInstr;
1047     } else
1048       PGOOpt = PGOOptions("",
1049                           CodeGenOpts.InstrProfileOutput.empty()
1050                               ? DefaultProfileGenName
1051                               : CodeGenOpts.InstrProfileOutput,
1052                           "", PGOOptions::NoAction, PGOOptions::CSIRInstr,
1053                           CodeGenOpts.DebugInfoForProfiling);
1054   }
1055 
1056   PipelineTuningOptions PTO;
1057   PTO.LoopUnrolling = CodeGenOpts.UnrollLoops;
1058   // For historical reasons, loop interleaving is set to mirror setting for loop
1059   // unrolling.
1060   PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
1061   PTO.LoopVectorization = CodeGenOpts.VectorizeLoop;
1062   PTO.SLPVectorization = CodeGenOpts.VectorizeSLP;
1063 
1064   PassBuilder PB(TM.get(), PTO, PGOOpt);
1065 
1066   // Attempt to load pass plugins and register their callbacks with PB.
1067   for (auto &PluginFN : CodeGenOpts.PassPlugins) {
1068     auto PassPlugin = PassPlugin::Load(PluginFN);
1069     if (PassPlugin) {
1070       PassPlugin->registerPassBuilderCallbacks(PB);
1071     } else {
1072       Diags.Report(diag::err_fe_unable_to_load_plugin)
1073           << PluginFN << toString(PassPlugin.takeError());
1074     }
1075   }
1076 
1077   LoopAnalysisManager LAM(CodeGenOpts.DebugPassManager);
1078   FunctionAnalysisManager FAM(CodeGenOpts.DebugPassManager);
1079   CGSCCAnalysisManager CGAM(CodeGenOpts.DebugPassManager);
1080   ModuleAnalysisManager MAM(CodeGenOpts.DebugPassManager);
1081 
1082   // Register the AA manager first so that our version is the one used.
1083   FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
1084 
1085   // Register the target library analysis directly and give it a customized
1086   // preset TLI.
1087   Triple TargetTriple(TheModule->getTargetTriple());
1088   std::unique_ptr<TargetLibraryInfoImpl> TLII(
1089       createTLII(TargetTriple, CodeGenOpts));
1090   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
1091   MAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
1092 
1093   // Register all the basic analyses with the managers.
1094   PB.registerModuleAnalyses(MAM);
1095   PB.registerCGSCCAnalyses(CGAM);
1096   PB.registerFunctionAnalyses(FAM);
1097   PB.registerLoopAnalyses(LAM);
1098   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
1099 
1100   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
1101 
1102   if (!CodeGenOpts.DisableLLVMPasses) {
1103     bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
1104     bool IsLTO = CodeGenOpts.PrepareForLTO;
1105 
1106     if (CodeGenOpts.OptimizationLevel == 0) {
1107       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1108         MPM.addPass(GCOVProfilerPass(*Options));
1109       if (Optional<InstrProfOptions> Options =
1110               getInstrProfOptions(CodeGenOpts, LangOpts))
1111         MPM.addPass(InstrProfiling(*Options, false));
1112 
1113       // Build a minimal pipeline based on the semantics required by Clang,
1114       // which is just that always inlining occurs. Further, disable generating
1115       // lifetime intrinsics to avoid enabling further optimizations during
1116       // code generation.
1117       MPM.addPass(AlwaysInlinerPass(/*InsertLifetimeIntrinsics=*/false));
1118 
1119       // At -O0 we directly run necessary sanitizer passes.
1120       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1121         MPM.addPass(createModuleToFunctionPassAdaptor(BoundsCheckingPass()));
1122 
1123       // Lastly, add semantically necessary passes for LTO.
1124       if (IsLTO || IsThinLTO) {
1125         MPM.addPass(CanonicalizeAliasesPass());
1126         MPM.addPass(NameAnonGlobalPass());
1127       }
1128     } else {
1129       // Map our optimization levels into one of the distinct levels used to
1130       // configure the pipeline.
1131       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
1132 
1133       PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1134         MPM.addPass(createModuleToFunctionPassAdaptor(
1135             EntryExitInstrumenterPass(/*PostInlining=*/false)));
1136       });
1137 
1138       // Register callbacks to schedule sanitizer passes at the appropriate part of
1139       // the pipeline.
1140       // FIXME: either handle asan/the remaining sanitizers or error out
1141       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1142         PB.registerScalarOptimizerLateEPCallback(
1143             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1144               FPM.addPass(BoundsCheckingPass());
1145             });
1146       if (LangOpts.Sanitize.has(SanitizerKind::Memory))
1147         PB.registerOptimizerLastEPCallback(
1148             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1149               FPM.addPass(MemorySanitizerPass({}));
1150             });
1151       if (LangOpts.Sanitize.has(SanitizerKind::Thread))
1152         PB.registerOptimizerLastEPCallback(
1153             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1154               FPM.addPass(ThreadSanitizerPass());
1155             });
1156       if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
1157         PB.registerPipelineStartEPCallback([&](ModulePassManager &MPM) {
1158           MPM.addPass(
1159               RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
1160         });
1161         bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::Address);
1162         bool UseAfterScope = CodeGenOpts.SanitizeAddressUseAfterScope;
1163         PB.registerOptimizerLastEPCallback(
1164             [Recover, UseAfterScope](FunctionPassManager &FPM,
1165                                      PassBuilder::OptimizationLevel Level) {
1166               FPM.addPass(AddressSanitizerPass(
1167                   /*CompileKernel=*/false, Recover, UseAfterScope));
1168             });
1169         bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
1170         bool UseOdrIndicator = CodeGenOpts.SanitizeAddressUseOdrIndicator;
1171         PB.registerPipelineStartEPCallback(
1172             [Recover, ModuleUseAfterScope,
1173              UseOdrIndicator](ModulePassManager &MPM) {
1174               MPM.addPass(ModuleAddressSanitizerPass(
1175                   /*CompileKernel=*/false, Recover, ModuleUseAfterScope,
1176                   UseOdrIndicator));
1177             });
1178       }
1179       if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
1180         bool Recover =
1181             CodeGenOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
1182         PB.registerOptimizerLastEPCallback(
1183             [Recover](FunctionPassManager &FPM,
1184                       PassBuilder::OptimizationLevel Level) {
1185               FPM.addPass(HWAddressSanitizerPass(
1186                   /*CompileKernel=*/false, Recover));
1187             });
1188       }
1189       if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
1190         PB.registerOptimizerLastEPCallback(
1191             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1192               FPM.addPass(HWAddressSanitizerPass(
1193                   /*CompileKernel=*/true, /*Recover=*/true));
1194             });
1195       }
1196       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1197         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1198           MPM.addPass(GCOVProfilerPass(*Options));
1199         });
1200       if (Optional<InstrProfOptions> Options =
1201               getInstrProfOptions(CodeGenOpts, LangOpts))
1202         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1203           MPM.addPass(InstrProfiling(*Options, false));
1204         });
1205 
1206       if (IsThinLTO) {
1207         MPM = PB.buildThinLTOPreLinkDefaultPipeline(
1208             Level, CodeGenOpts.DebugPassManager);
1209         MPM.addPass(CanonicalizeAliasesPass());
1210         MPM.addPass(NameAnonGlobalPass());
1211       } else if (IsLTO) {
1212         MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
1213                                                 CodeGenOpts.DebugPassManager);
1214         MPM.addPass(CanonicalizeAliasesPass());
1215         MPM.addPass(NameAnonGlobalPass());
1216       } else {
1217         MPM = PB.buildPerModuleDefaultPipeline(Level,
1218                                                CodeGenOpts.DebugPassManager);
1219       }
1220     }
1221 
1222     if (CodeGenOpts.OptimizationLevel == 0)
1223       addSanitizersAtO0(MPM, TargetTriple, LangOpts, CodeGenOpts);
1224   }
1225 
1226   // FIXME: We still use the legacy pass manager to do code generation. We
1227   // create that pass manager here and use it as needed below.
1228   legacy::PassManager CodeGenPasses;
1229   bool NeedCodeGen = false;
1230   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
1231 
1232   // Append any output we need to the pass manager.
1233   switch (Action) {
1234   case Backend_EmitNothing:
1235     break;
1236 
1237   case Backend_EmitBC:
1238     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
1239       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
1240         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
1241         if (!ThinLinkOS)
1242           return;
1243       }
1244       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1245                                CodeGenOpts.EnableSplitLTOUnit);
1246       MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
1247                                                            : nullptr));
1248     } else {
1249       // Emit a module summary by default for Regular LTO except for ld64
1250       // targets
1251       bool EmitLTOSummary =
1252           (CodeGenOpts.PrepareForLTO &&
1253            !CodeGenOpts.DisableLLVMPasses &&
1254            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
1255                llvm::Triple::Apple);
1256       if (EmitLTOSummary) {
1257         if (!TheModule->getModuleFlag("ThinLTO"))
1258           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
1259         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1260                                  CodeGenOpts.EnableSplitLTOUnit);
1261       }
1262       MPM.addPass(
1263           BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
1264     }
1265     break;
1266 
1267   case Backend_EmitLL:
1268     MPM.addPass(PrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
1269     break;
1270 
1271   case Backend_EmitAssembly:
1272   case Backend_EmitMCNull:
1273   case Backend_EmitObj:
1274     NeedCodeGen = true;
1275     CodeGenPasses.add(
1276         createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
1277     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
1278       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
1279       if (!DwoOS)
1280         return;
1281     }
1282     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
1283                        DwoOS ? &DwoOS->os() : nullptr))
1284       // FIXME: Should we handle this error differently?
1285       return;
1286     break;
1287   }
1288 
1289   // Before executing passes, print the final values of the LLVM options.
1290   cl::PrintOptionValues();
1291 
1292   // Now that we have all of the passes ready, run them.
1293   {
1294     PrettyStackTraceString CrashInfo("Optimizer");
1295     MPM.run(*TheModule, MAM);
1296   }
1297 
1298   // Now if needed, run the legacy PM for codegen.
1299   if (NeedCodeGen) {
1300     PrettyStackTraceString CrashInfo("Code generation");
1301     CodeGenPasses.run(*TheModule);
1302   }
1303 
1304   if (ThinLinkOS)
1305     ThinLinkOS->keep();
1306   if (DwoOS)
1307     DwoOS->keep();
1308 }
1309 
1310 Expected<BitcodeModule> clang::FindThinLTOModule(MemoryBufferRef MBRef) {
1311   Expected<std::vector<BitcodeModule>> BMsOrErr = getBitcodeModuleList(MBRef);
1312   if (!BMsOrErr)
1313     return BMsOrErr.takeError();
1314 
1315   // The bitcode file may contain multiple modules, we want the one that is
1316   // marked as being the ThinLTO module.
1317   if (const BitcodeModule *Bm = FindThinLTOModule(*BMsOrErr))
1318     return *Bm;
1319 
1320   return make_error<StringError>("Could not find module summary",
1321                                  inconvertibleErrorCode());
1322 }
1323 
1324 BitcodeModule *clang::FindThinLTOModule(MutableArrayRef<BitcodeModule> BMs) {
1325   for (BitcodeModule &BM : BMs) {
1326     Expected<BitcodeLTOInfo> LTOInfo = BM.getLTOInfo();
1327     if (LTOInfo && LTOInfo->IsThinLTO)
1328       return &BM;
1329   }
1330   return nullptr;
1331 }
1332 
1333 static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
1334                               const HeaderSearchOptions &HeaderOpts,
1335                               const CodeGenOptions &CGOpts,
1336                               const clang::TargetOptions &TOpts,
1337                               const LangOptions &LOpts,
1338                               std::unique_ptr<raw_pwrite_stream> OS,
1339                               std::string SampleProfile,
1340                               std::string ProfileRemapping,
1341                               BackendAction Action) {
1342   StringMap<DenseMap<GlobalValue::GUID, GlobalValueSummary *>>
1343       ModuleToDefinedGVSummaries;
1344   CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
1345 
1346   setCommandLineOpts(CGOpts);
1347 
1348   // We can simply import the values mentioned in the combined index, since
1349   // we should only invoke this using the individual indexes written out
1350   // via a WriteIndexesThinBackend.
1351   FunctionImporter::ImportMapTy ImportList;
1352   for (auto &GlobalList : *CombinedIndex) {
1353     // Ignore entries for undefined references.
1354     if (GlobalList.second.SummaryList.empty())
1355       continue;
1356 
1357     auto GUID = GlobalList.first;
1358     for (auto &Summary : GlobalList.second.SummaryList) {
1359       // Skip the summaries for the importing module. These are included to
1360       // e.g. record required linkage changes.
1361       if (Summary->modulePath() == M->getModuleIdentifier())
1362         continue;
1363       // Add an entry to provoke importing by thinBackend.
1364       ImportList[Summary->modulePath()].insert(GUID);
1365     }
1366   }
1367 
1368   std::vector<std::unique_ptr<llvm::MemoryBuffer>> OwnedImports;
1369   MapVector<llvm::StringRef, llvm::BitcodeModule> ModuleMap;
1370 
1371   for (auto &I : ImportList) {
1372     ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> MBOrErr =
1373         llvm::MemoryBuffer::getFile(I.first());
1374     if (!MBOrErr) {
1375       errs() << "Error loading imported file '" << I.first()
1376              << "': " << MBOrErr.getError().message() << "\n";
1377       return;
1378     }
1379 
1380     Expected<BitcodeModule> BMOrErr = FindThinLTOModule(**MBOrErr);
1381     if (!BMOrErr) {
1382       handleAllErrors(BMOrErr.takeError(), [&](ErrorInfoBase &EIB) {
1383         errs() << "Error loading imported file '" << I.first()
1384                << "': " << EIB.message() << '\n';
1385       });
1386       return;
1387     }
1388     ModuleMap.insert({I.first(), *BMOrErr});
1389 
1390     OwnedImports.push_back(std::move(*MBOrErr));
1391   }
1392   auto AddStream = [&](size_t Task) {
1393     return llvm::make_unique<lto::NativeObjectStream>(std::move(OS));
1394   };
1395   lto::Config Conf;
1396   if (CGOpts.SaveTempsFilePrefix != "") {
1397     if (Error E = Conf.addSaveTemps(CGOpts.SaveTempsFilePrefix + ".",
1398                                     /* UseInputModulePath */ false)) {
1399       handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1400         errs() << "Error setting up ThinLTO save-temps: " << EIB.message()
1401                << '\n';
1402       });
1403     }
1404   }
1405   Conf.CPU = TOpts.CPU;
1406   Conf.CodeModel = getCodeModel(CGOpts);
1407   Conf.MAttrs = TOpts.Features;
1408   Conf.RelocModel = CGOpts.RelocationModel;
1409   Conf.CGOptLevel = getCGOptLevel(CGOpts);
1410   Conf.OptLevel = CGOpts.OptimizationLevel;
1411   initTargetOptions(Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
1412   Conf.SampleProfile = std::move(SampleProfile);
1413 
1414   // Context sensitive profile.
1415   if (CGOpts.hasProfileCSIRInstr()) {
1416     Conf.RunCSIRInstr = true;
1417     Conf.CSIRProfile = std::move(CGOpts.InstrProfileOutput);
1418   } else if (CGOpts.hasProfileCSIRUse()) {
1419     Conf.RunCSIRInstr = false;
1420     Conf.CSIRProfile = std::move(CGOpts.ProfileInstrumentUsePath);
1421   }
1422 
1423   Conf.ProfileRemapping = std::move(ProfileRemapping);
1424   Conf.UseNewPM = CGOpts.ExperimentalNewPassManager;
1425   Conf.DebugPassManager = CGOpts.DebugPassManager;
1426   Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
1427   Conf.RemarksFilename = CGOpts.OptRecordFile;
1428   Conf.RemarksPasses = CGOpts.OptRecordPasses;
1429   Conf.RemarksFormat = CGOpts.OptRecordFormat;
1430   Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
1431   Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
1432   switch (Action) {
1433   case Backend_EmitNothing:
1434     Conf.PreCodeGenModuleHook = [](size_t Task, const Module &Mod) {
1435       return false;
1436     };
1437     break;
1438   case Backend_EmitLL:
1439     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1440       M->print(*OS, nullptr, CGOpts.EmitLLVMUseLists);
1441       return false;
1442     };
1443     break;
1444   case Backend_EmitBC:
1445     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1446       WriteBitcodeToFile(*M, *OS, CGOpts.EmitLLVMUseLists);
1447       return false;
1448     };
1449     break;
1450   default:
1451     Conf.CGFileType = getCodeGenFileType(Action);
1452     break;
1453   }
1454   if (Error E = thinBackend(
1455           Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
1456           ModuleToDefinedGVSummaries[M->getModuleIdentifier()], ModuleMap)) {
1457     handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1458       errs() << "Error running ThinLTO backend: " << EIB.message() << '\n';
1459     });
1460   }
1461 }
1462 
1463 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
1464                               const HeaderSearchOptions &HeaderOpts,
1465                               const CodeGenOptions &CGOpts,
1466                               const clang::TargetOptions &TOpts,
1467                               const LangOptions &LOpts,
1468                               const llvm::DataLayout &TDesc, Module *M,
1469                               BackendAction Action,
1470                               std::unique_ptr<raw_pwrite_stream> OS) {
1471 
1472   llvm::TimeTraceScope TimeScope("Backend", StringRef(""));
1473 
1474   std::unique_ptr<llvm::Module> EmptyModule;
1475   if (!CGOpts.ThinLTOIndexFile.empty()) {
1476     // If we are performing a ThinLTO importing compile, load the function index
1477     // into memory and pass it into runThinLTOBackend, which will run the
1478     // function importer and invoke LTO passes.
1479     Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
1480         llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile,
1481                                            /*IgnoreEmptyThinLTOIndexFile*/true);
1482     if (!IndexOrErr) {
1483       logAllUnhandledErrors(IndexOrErr.takeError(), errs(),
1484                             "Error loading index file '" +
1485                             CGOpts.ThinLTOIndexFile + "': ");
1486       return;
1487     }
1488     std::unique_ptr<ModuleSummaryIndex> CombinedIndex = std::move(*IndexOrErr);
1489     // A null CombinedIndex means we should skip ThinLTO compilation
1490     // (LLVM will optionally ignore empty index files, returning null instead
1491     // of an error).
1492     if (CombinedIndex) {
1493       if (!CombinedIndex->skipModuleByDistributedBackend()) {
1494         runThinLTOBackend(CombinedIndex.get(), M, HeaderOpts, CGOpts, TOpts,
1495                           LOpts, std::move(OS), CGOpts.SampleProfileFile,
1496                           CGOpts.ProfileRemappingFile, Action);
1497         return;
1498       }
1499       // Distributed indexing detected that nothing from the module is needed
1500       // for the final linking. So we can skip the compilation. We sill need to
1501       // output an empty object file to make sure that a linker does not fail
1502       // trying to read it. Also for some features, like CFI, we must skip
1503       // the compilation as CombinedIndex does not contain all required
1504       // information.
1505       EmptyModule = llvm::make_unique<llvm::Module>("empty", M->getContext());
1506       EmptyModule->setTargetTriple(M->getTargetTriple());
1507       M = EmptyModule.get();
1508     }
1509   }
1510 
1511   EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
1512 
1513   if (CGOpts.ExperimentalNewPassManager)
1514     AsmHelper.EmitAssemblyWithNewPassManager(Action, std::move(OS));
1515   else
1516     AsmHelper.EmitAssembly(Action, std::move(OS));
1517 
1518   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
1519   // DataLayout.
1520   if (AsmHelper.TM) {
1521     std::string DLDesc = M->getDataLayout().getStringRepresentation();
1522     if (DLDesc != TDesc.getStringRepresentation()) {
1523       unsigned DiagID = Diags.getCustomDiagID(
1524           DiagnosticsEngine::Error, "backend data layout '%0' does not match "
1525                                     "expected target description '%1'");
1526       Diags.Report(DiagID) << DLDesc << TDesc.getStringRepresentation();
1527     }
1528   }
1529 }
1530 
1531 static const char* getSectionNameForBitcode(const Triple &T) {
1532   switch (T.getObjectFormat()) {
1533   case Triple::MachO:
1534     return "__LLVM,__bitcode";
1535   case Triple::COFF:
1536   case Triple::ELF:
1537   case Triple::Wasm:
1538   case Triple::UnknownObjectFormat:
1539     return ".llvmbc";
1540   case Triple::XCOFF:
1541     llvm_unreachable("XCOFF is not yet implemented");
1542     break;
1543   }
1544   llvm_unreachable("Unimplemented ObjectFormatType");
1545 }
1546 
1547 static const char* getSectionNameForCommandline(const Triple &T) {
1548   switch (T.getObjectFormat()) {
1549   case Triple::MachO:
1550     return "__LLVM,__cmdline";
1551   case Triple::COFF:
1552   case Triple::ELF:
1553   case Triple::Wasm:
1554   case Triple::UnknownObjectFormat:
1555     return ".llvmcmd";
1556   case Triple::XCOFF:
1557     llvm_unreachable("XCOFF is not yet implemented");
1558     break;
1559   }
1560   llvm_unreachable("Unimplemented ObjectFormatType");
1561 }
1562 
1563 // With -fembed-bitcode, save a copy of the llvm IR as data in the
1564 // __LLVM,__bitcode section.
1565 void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
1566                          llvm::MemoryBufferRef Buf) {
1567   if (CGOpts.getEmbedBitcode() == CodeGenOptions::Embed_Off)
1568     return;
1569 
1570   // Save llvm.compiler.used and remote it.
1571   SmallVector<Constant*, 2> UsedArray;
1572   SmallPtrSet<GlobalValue*, 4> UsedGlobals;
1573   Type *UsedElementType = Type::getInt8Ty(M->getContext())->getPointerTo(0);
1574   GlobalVariable *Used = collectUsedGlobalVariables(*M, UsedGlobals, true);
1575   for (auto *GV : UsedGlobals) {
1576     if (GV->getName() != "llvm.embedded.module" &&
1577         GV->getName() != "llvm.cmdline")
1578       UsedArray.push_back(
1579           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
1580   }
1581   if (Used)
1582     Used->eraseFromParent();
1583 
1584   // Embed the bitcode for the llvm module.
1585   std::string Data;
1586   ArrayRef<uint8_t> ModuleData;
1587   Triple T(M->getTargetTriple());
1588   // Create a constant that contains the bitcode.
1589   // In case of embedding a marker, ignore the input Buf and use the empty
1590   // ArrayRef. It is also legal to create a bitcode marker even Buf is empty.
1591   if (CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Marker) {
1592     if (!isBitcode((const unsigned char *)Buf.getBufferStart(),
1593                    (const unsigned char *)Buf.getBufferEnd())) {
1594       // If the input is LLVM Assembly, bitcode is produced by serializing
1595       // the module. Use-lists order need to be perserved in this case.
1596       llvm::raw_string_ostream OS(Data);
1597       llvm::WriteBitcodeToFile(*M, OS, /* ShouldPreserveUseListOrder */ true);
1598       ModuleData =
1599           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
1600     } else
1601       // If the input is LLVM bitcode, write the input byte stream directly.
1602       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
1603                                      Buf.getBufferSize());
1604   }
1605   llvm::Constant *ModuleConstant =
1606       llvm::ConstantDataArray::get(M->getContext(), ModuleData);
1607   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
1608       *M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
1609       ModuleConstant);
1610   GV->setSection(getSectionNameForBitcode(T));
1611   UsedArray.push_back(
1612       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
1613   if (llvm::GlobalVariable *Old =
1614           M->getGlobalVariable("llvm.embedded.module", true)) {
1615     assert(Old->hasOneUse() &&
1616            "llvm.embedded.module can only be used once in llvm.compiler.used");
1617     GV->takeName(Old);
1618     Old->eraseFromParent();
1619   } else {
1620     GV->setName("llvm.embedded.module");
1621   }
1622 
1623   // Skip if only bitcode needs to be embedded.
1624   if (CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Bitcode) {
1625     // Embed command-line options.
1626     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CGOpts.CmdArgs.data()),
1627                               CGOpts.CmdArgs.size());
1628     llvm::Constant *CmdConstant =
1629       llvm::ConstantDataArray::get(M->getContext(), CmdData);
1630     GV = new llvm::GlobalVariable(*M, CmdConstant->getType(), true,
1631                                   llvm::GlobalValue::PrivateLinkage,
1632                                   CmdConstant);
1633     GV->setSection(getSectionNameForCommandline(T));
1634     UsedArray.push_back(
1635         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
1636     if (llvm::GlobalVariable *Old =
1637             M->getGlobalVariable("llvm.cmdline", true)) {
1638       assert(Old->hasOneUse() &&
1639              "llvm.cmdline can only be used once in llvm.compiler.used");
1640       GV->takeName(Old);
1641       Old->eraseFromParent();
1642     } else {
1643       GV->setName("llvm.cmdline");
1644     }
1645   }
1646 
1647   if (UsedArray.empty())
1648     return;
1649 
1650   // Recreate llvm.compiler.used.
1651   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
1652   auto *NewUsed = new GlobalVariable(
1653       *M, ATy, false, llvm::GlobalValue::AppendingLinkage,
1654       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
1655   NewUsed->setSection("llvm.metadata");
1656 }
1657