xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/BackendUtil.cpp (revision a7dea1671b87c07d2d266f836bfa8b58efc7c134) 
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 namespace {
79 
80 // Default filename used for profile generation.
81 static constexpr StringLiteral DefaultProfileGenName = "default_%m.profraw";
82 
83 class EmitAssemblyHelper {
84   DiagnosticsEngine &Diags;
85   const HeaderSearchOptions &HSOpts;
86   const CodeGenOptions &CodeGenOpts;
87   const clang::TargetOptions &TargetOpts;
88   const LangOptions &LangOpts;
89   Module *TheModule;
90 
91   Timer CodeGenerationTime;
92 
93   std::unique_ptr<raw_pwrite_stream> OS;
94 
95   TargetIRAnalysis getTargetIRAnalysis() const {
96     if (TM)
97       return TM->getTargetIRAnalysis();
98 
99     return TargetIRAnalysis();
100   }
101 
102   void CreatePasses(legacy::PassManager &MPM, legacy::FunctionPassManager &FPM);
103 
104   /// Generates the TargetMachine.
105   /// Leaves TM unchanged if it is unable to create the target machine.
106   /// Some of our clang tests specify triples which are not built
107   /// into clang. This is okay because these tests check the generated
108   /// IR, and they require DataLayout which depends on the triple.
109   /// In this case, we allow this method to fail and not report an error.
110   /// When MustCreateTM is used, we print an error if we are unable to load
111   /// the requested target.
112   void CreateTargetMachine(bool MustCreateTM);
113 
114   /// Add passes necessary to emit assembly or LLVM IR.
115   ///
116   /// \return True on success.
117   bool AddEmitPasses(legacy::PassManager &CodeGenPasses, BackendAction Action,
118                      raw_pwrite_stream &OS, raw_pwrite_stream *DwoOS);
119 
120   std::unique_ptr<llvm::ToolOutputFile> openOutputFile(StringRef Path) {
121     std::error_code EC;
122     auto F = std::make_unique<llvm::ToolOutputFile>(Path, EC,
123                                                      llvm::sys::fs::OF_None);
124     if (EC) {
125       Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
126       F.reset();
127     }
128     return F;
129   }
130 
131 public:
132   EmitAssemblyHelper(DiagnosticsEngine &_Diags,
133                      const HeaderSearchOptions &HeaderSearchOpts,
134                      const CodeGenOptions &CGOpts,
135                      const clang::TargetOptions &TOpts,
136                      const LangOptions &LOpts, Module *M)
137       : Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
138         TargetOpts(TOpts), LangOpts(LOpts), TheModule(M),
139         CodeGenerationTime("codegen", "Code Generation Time") {}
140 
141   ~EmitAssemblyHelper() {
142     if (CodeGenOpts.DisableFree)
143       BuryPointer(std::move(TM));
144   }
145 
146   std::unique_ptr<TargetMachine> TM;
147 
148   void EmitAssembly(BackendAction Action,
149                     std::unique_ptr<raw_pwrite_stream> OS);
150 
151   void EmitAssemblyWithNewPassManager(BackendAction Action,
152                                       std::unique_ptr<raw_pwrite_stream> OS);
153 };
154 
155 // We need this wrapper to access LangOpts and CGOpts from extension functions
156 // that we add to the PassManagerBuilder.
157 class PassManagerBuilderWrapper : public PassManagerBuilder {
158 public:
159   PassManagerBuilderWrapper(const Triple &TargetTriple,
160                             const CodeGenOptions &CGOpts,
161                             const LangOptions &LangOpts)
162       : PassManagerBuilder(), TargetTriple(TargetTriple), CGOpts(CGOpts),
163         LangOpts(LangOpts) {}
164   const Triple &getTargetTriple() const { return TargetTriple; }
165   const CodeGenOptions &getCGOpts() const { return CGOpts; }
166   const LangOptions &getLangOpts() const { return LangOpts; }
167 
168 private:
169   const Triple &TargetTriple;
170   const CodeGenOptions &CGOpts;
171   const LangOptions &LangOpts;
172 };
173 }
174 
175 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
176   if (Builder.OptLevel > 0)
177     PM.add(createObjCARCAPElimPass());
178 }
179 
180 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
181   if (Builder.OptLevel > 0)
182     PM.add(createObjCARCExpandPass());
183 }
184 
185 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
186   if (Builder.OptLevel > 0)
187     PM.add(createObjCARCOptPass());
188 }
189 
190 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
191                                      legacy::PassManagerBase &PM) {
192   PM.add(createAddDiscriminatorsPass());
193 }
194 
195 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
196                                   legacy::PassManagerBase &PM) {
197   PM.add(createBoundsCheckingLegacyPass());
198 }
199 
200 static SanitizerCoverageOptions
201 getSancovOptsFromCGOpts(const CodeGenOptions &CGOpts) {
202   SanitizerCoverageOptions Opts;
203   Opts.CoverageType =
204       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
205   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
206   Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
207   Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
208   Opts.TraceDiv = CGOpts.SanitizeCoverageTraceDiv;
209   Opts.TraceGep = CGOpts.SanitizeCoverageTraceGep;
210   Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
211   Opts.TracePC = CGOpts.SanitizeCoverageTracePC;
212   Opts.TracePCGuard = CGOpts.SanitizeCoverageTracePCGuard;
213   Opts.NoPrune = CGOpts.SanitizeCoverageNoPrune;
214   Opts.Inline8bitCounters = CGOpts.SanitizeCoverageInline8bitCounters;
215   Opts.PCTable = CGOpts.SanitizeCoveragePCTable;
216   Opts.StackDepth = CGOpts.SanitizeCoverageStackDepth;
217   return Opts;
218 }
219 
220 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
221                                      legacy::PassManagerBase &PM) {
222   const PassManagerBuilderWrapper &BuilderWrapper =
223       static_cast<const PassManagerBuilderWrapper &>(Builder);
224   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
225   auto Opts = getSancovOptsFromCGOpts(CGOpts);
226   PM.add(createModuleSanitizerCoverageLegacyPassPass(Opts));
227 }
228 
229 // Check if ASan should use GC-friendly instrumentation for globals.
230 // First of all, there is no point if -fdata-sections is off (expect for MachO,
231 // where this is not a factor). Also, on ELF this feature requires an assembler
232 // extension that only works with -integrated-as at the moment.
233 static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
234   if (!CGOpts.SanitizeAddressGlobalsDeadStripping)
235     return false;
236   switch (T.getObjectFormat()) {
237   case Triple::MachO:
238   case Triple::COFF:
239     return true;
240   case Triple::ELF:
241     return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
242   case Triple::XCOFF:
243     llvm::report_fatal_error("ASan not implemented for XCOFF.");
244   case Triple::Wasm:
245   case Triple::UnknownObjectFormat:
246     break;
247   }
248   return false;
249 }
250 
251 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
252                                       legacy::PassManagerBase &PM) {
253   const PassManagerBuilderWrapper &BuilderWrapper =
254       static_cast<const PassManagerBuilderWrapper&>(Builder);
255   const Triple &T = BuilderWrapper.getTargetTriple();
256   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
257   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
258   bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
259   bool UseOdrIndicator = CGOpts.SanitizeAddressUseOdrIndicator;
260   bool UseGlobalsGC = asanUseGlobalsGC(T, CGOpts);
261   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
262                                             UseAfterScope));
263   PM.add(createModuleAddressSanitizerLegacyPassPass(
264       /*CompileKernel*/ false, Recover, UseGlobalsGC, UseOdrIndicator));
265 }
266 
267 static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
268                                             legacy::PassManagerBase &PM) {
269   PM.add(createAddressSanitizerFunctionPass(
270       /*CompileKernel*/ true, /*Recover*/ true, /*UseAfterScope*/ false));
271   PM.add(createModuleAddressSanitizerLegacyPassPass(
272       /*CompileKernel*/ true, /*Recover*/ true, /*UseGlobalsGC*/ true,
273       /*UseOdrIndicator*/ false));
274 }
275 
276 static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
277                                             legacy::PassManagerBase &PM) {
278   const PassManagerBuilderWrapper &BuilderWrapper =
279       static_cast<const PassManagerBuilderWrapper &>(Builder);
280   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
281   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
282   PM.add(
283       createHWAddressSanitizerLegacyPassPass(/*CompileKernel*/ false, Recover));
284 }
285 
286 static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
287                                             legacy::PassManagerBase &PM) {
288   PM.add(createHWAddressSanitizerLegacyPassPass(
289       /*CompileKernel*/ true, /*Recover*/ true));
290 }
291 
292 static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
293                                              legacy::PassManagerBase &PM,
294                                              bool CompileKernel) {
295   const PassManagerBuilderWrapper &BuilderWrapper =
296       static_cast<const PassManagerBuilderWrapper&>(Builder);
297   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
298   int TrackOrigins = CGOpts.SanitizeMemoryTrackOrigins;
299   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Memory);
300   PM.add(createMemorySanitizerLegacyPassPass(
301       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
302 
303   // MemorySanitizer inserts complex instrumentation that mostly follows
304   // the logic of the original code, but operates on "shadow" values.
305   // It can benefit from re-running some general purpose optimization passes.
306   if (Builder.OptLevel > 0) {
307     PM.add(createEarlyCSEPass());
308     PM.add(createReassociatePass());
309     PM.add(createLICMPass());
310     PM.add(createGVNPass());
311     PM.add(createInstructionCombiningPass());
312     PM.add(createDeadStoreEliminationPass());
313   }
314 }
315 
316 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
317                                    legacy::PassManagerBase &PM) {
318   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ false);
319 }
320 
321 static void addKernelMemorySanitizerPass(const PassManagerBuilder &Builder,
322                                          legacy::PassManagerBase &PM) {
323   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ true);
324 }
325 
326 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
327                                    legacy::PassManagerBase &PM) {
328   PM.add(createThreadSanitizerLegacyPassPass());
329 }
330 
331 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
332                                      legacy::PassManagerBase &PM) {
333   const PassManagerBuilderWrapper &BuilderWrapper =
334       static_cast<const PassManagerBuilderWrapper&>(Builder);
335   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
336   PM.add(createDataFlowSanitizerPass(LangOpts.SanitizerBlacklistFiles));
337 }
338 
339 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
340                                          const CodeGenOptions &CodeGenOpts) {
341   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
342   if (!CodeGenOpts.SimplifyLibCalls)
343     TLII->disableAllFunctions();
344   else {
345     // Disable individual libc/libm calls in TargetLibraryInfo.
346     LibFunc F;
347     for (auto &FuncName : CodeGenOpts.getNoBuiltinFuncs())
348       if (TLII->getLibFunc(FuncName, F))
349         TLII->setUnavailable(F);
350   }
351 
352   switch (CodeGenOpts.getVecLib()) {
353   case CodeGenOptions::Accelerate:
354     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
355     break;
356   case CodeGenOptions::MASSV:
357     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::MASSV);
358     break;
359   case CodeGenOptions::SVML:
360     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::SVML);
361     break;
362   default:
363     break;
364   }
365   return TLII;
366 }
367 
368 static void addSymbolRewriterPass(const CodeGenOptions &Opts,
369                                   legacy::PassManager *MPM) {
370   llvm::SymbolRewriter::RewriteDescriptorList DL;
371 
372   llvm::SymbolRewriter::RewriteMapParser MapParser;
373   for (const auto &MapFile : Opts.RewriteMapFiles)
374     MapParser.parse(MapFile, &DL);
375 
376   MPM->add(createRewriteSymbolsPass(DL));
377 }
378 
379 static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
380   switch (CodeGenOpts.OptimizationLevel) {
381   default:
382     llvm_unreachable("Invalid optimization level!");
383   case 0:
384     return CodeGenOpt::None;
385   case 1:
386     return CodeGenOpt::Less;
387   case 2:
388     return CodeGenOpt::Default; // O2/Os/Oz
389   case 3:
390     return CodeGenOpt::Aggressive;
391   }
392 }
393 
394 static Optional<llvm::CodeModel::Model>
395 getCodeModel(const CodeGenOptions &CodeGenOpts) {
396   unsigned CodeModel = llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
397                            .Case("tiny", llvm::CodeModel::Tiny)
398                            .Case("small", llvm::CodeModel::Small)
399                            .Case("kernel", llvm::CodeModel::Kernel)
400                            .Case("medium", llvm::CodeModel::Medium)
401                            .Case("large", llvm::CodeModel::Large)
402                            .Case("default", ~1u)
403                            .Default(~0u);
404   assert(CodeModel != ~0u && "invalid code model!");
405   if (CodeModel == ~1u)
406     return None;
407   return static_cast<llvm::CodeModel::Model>(CodeModel);
408 }
409 
410 static TargetMachine::CodeGenFileType getCodeGenFileType(BackendAction Action) {
411   if (Action == Backend_EmitObj)
412     return TargetMachine::CGFT_ObjectFile;
413   else if (Action == Backend_EmitMCNull)
414     return TargetMachine::CGFT_Null;
415   else {
416     assert(Action == Backend_EmitAssembly && "Invalid action!");
417     return TargetMachine::CGFT_AssemblyFile;
418   }
419 }
420 
421 static void initTargetOptions(llvm::TargetOptions &Options,
422                               const CodeGenOptions &CodeGenOpts,
423                               const clang::TargetOptions &TargetOpts,
424                               const LangOptions &LangOpts,
425                               const HeaderSearchOptions &HSOpts) {
426   Options.ThreadModel =
427       llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
428           .Case("posix", llvm::ThreadModel::POSIX)
429           .Case("single", llvm::ThreadModel::Single);
430 
431   // Set float ABI type.
432   assert((CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp" ||
433           CodeGenOpts.FloatABI == "hard" || CodeGenOpts.FloatABI.empty()) &&
434          "Invalid Floating Point ABI!");
435   Options.FloatABIType =
436       llvm::StringSwitch<llvm::FloatABI::ABIType>(CodeGenOpts.FloatABI)
437           .Case("soft", llvm::FloatABI::Soft)
438           .Case("softfp", llvm::FloatABI::Soft)
439           .Case("hard", llvm::FloatABI::Hard)
440           .Default(llvm::FloatABI::Default);
441 
442   // Set FP fusion mode.
443   switch (LangOpts.getDefaultFPContractMode()) {
444   case LangOptions::FPC_Off:
445     // Preserve any contraction performed by the front-end.  (Strict performs
446     // splitting of the muladd intrinsic in the backend.)
447     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
448     break;
449   case LangOptions::FPC_On:
450     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
451     break;
452   case LangOptions::FPC_Fast:
453     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
454     break;
455   }
456 
457   Options.UseInitArray = CodeGenOpts.UseInitArray;
458   Options.DisableIntegratedAS = CodeGenOpts.DisableIntegratedAS;
459   Options.CompressDebugSections = CodeGenOpts.getCompressDebugSections();
460   Options.RelaxELFRelocations = CodeGenOpts.RelaxELFRelocations;
461 
462   // Set EABI version.
463   Options.EABIVersion = TargetOpts.EABIVersion;
464 
465   if (LangOpts.SjLjExceptions)
466     Options.ExceptionModel = llvm::ExceptionHandling::SjLj;
467   if (LangOpts.SEHExceptions)
468     Options.ExceptionModel = llvm::ExceptionHandling::WinEH;
469   if (LangOpts.DWARFExceptions)
470     Options.ExceptionModel = llvm::ExceptionHandling::DwarfCFI;
471   if (LangOpts.WasmExceptions)
472     Options.ExceptionModel = llvm::ExceptionHandling::Wasm;
473 
474   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
475   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
476   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
477   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
478   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
479   Options.FunctionSections = CodeGenOpts.FunctionSections;
480   Options.DataSections = CodeGenOpts.DataSections;
481   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
482   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
483   Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
484   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
485   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
486   Options.EmitAddrsig = CodeGenOpts.Addrsig;
487   Options.EnableDebugEntryValues = CodeGenOpts.EnableDebugEntryValues;
488 
489   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
490   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
491   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
492   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
493   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
494   Options.MCOptions.MCIncrementalLinkerCompatible =
495       CodeGenOpts.IncrementalLinkerCompatible;
496   Options.MCOptions.MCPIECopyRelocations = CodeGenOpts.PIECopyRelocations;
497   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
498   Options.MCOptions.MCNoWarn = CodeGenOpts.NoWarn;
499   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
500   Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
501   Options.MCOptions.ABIName = TargetOpts.ABI;
502   for (const auto &Entry : HSOpts.UserEntries)
503     if (!Entry.IsFramework &&
504         (Entry.Group == frontend::IncludeDirGroup::Quoted ||
505          Entry.Group == frontend::IncludeDirGroup::Angled ||
506          Entry.Group == frontend::IncludeDirGroup::System))
507       Options.MCOptions.IASSearchPaths.push_back(
508           Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);
509 }
510 static Optional<GCOVOptions> getGCOVOptions(const CodeGenOptions &CodeGenOpts) {
511   if (CodeGenOpts.DisableGCov)
512     return None;
513   if (!CodeGenOpts.EmitGcovArcs && !CodeGenOpts.EmitGcovNotes)
514     return None;
515   // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
516   // LLVM's -default-gcov-version flag is set to something invalid.
517   GCOVOptions Options;
518   Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
519   Options.EmitData = CodeGenOpts.EmitGcovArcs;
520   llvm::copy(CodeGenOpts.CoverageVersion, std::begin(Options.Version));
521   Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
522   Options.NoRedZone = CodeGenOpts.DisableRedZone;
523   Options.FunctionNamesInData = !CodeGenOpts.CoverageNoFunctionNamesInData;
524   Options.Filter = CodeGenOpts.ProfileFilterFiles;
525   Options.Exclude = CodeGenOpts.ProfileExcludeFiles;
526   Options.ExitBlockBeforeBody = CodeGenOpts.CoverageExitBlockBeforeBody;
527   return Options;
528 }
529 
530 static Optional<InstrProfOptions>
531 getInstrProfOptions(const CodeGenOptions &CodeGenOpts,
532                     const LangOptions &LangOpts) {
533   if (!CodeGenOpts.hasProfileClangInstr())
534     return None;
535   InstrProfOptions Options;
536   Options.NoRedZone = CodeGenOpts.DisableRedZone;
537   Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
538 
539   // TODO: Surface the option to emit atomic profile counter increments at
540   // the driver level.
541   Options.Atomic = LangOpts.Sanitize.has(SanitizerKind::Thread);
542   return Options;
543 }
544 
545 void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
546                                       legacy::FunctionPassManager &FPM) {
547   // Handle disabling of all LLVM passes, where we want to preserve the
548   // internal module before any optimization.
549   if (CodeGenOpts.DisableLLVMPasses)
550     return;
551 
552   // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
553   // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
554   // are inserted before PMBuilder ones - they'd get the default-constructed
555   // TLI with an unknown target otherwise.
556   Triple TargetTriple(TheModule->getTargetTriple());
557   std::unique_ptr<TargetLibraryInfoImpl> TLII(
558       createTLII(TargetTriple, CodeGenOpts));
559 
560   PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
561 
562   // At O0 and O1 we only run the always inliner which is more efficient. At
563   // higher optimization levels we run the normal inliner.
564   if (CodeGenOpts.OptimizationLevel <= 1) {
565     bool InsertLifetimeIntrinsics = (CodeGenOpts.OptimizationLevel != 0 &&
566                                      !CodeGenOpts.DisableLifetimeMarkers);
567     PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
568   } else {
569     // We do not want to inline hot callsites for SamplePGO module-summary build
570     // because profile annotation will happen again in ThinLTO backend, and we
571     // want the IR of the hot path to match the profile.
572     PMBuilder.Inliner = createFunctionInliningPass(
573         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
574         (!CodeGenOpts.SampleProfileFile.empty() &&
575          CodeGenOpts.PrepareForThinLTO));
576   }
577 
578   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
579   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
580   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
581   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
582 
583   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
584   // Loop interleaving in the loop vectorizer has historically been set to be
585   // enabled when loop unrolling is enabled.
586   PMBuilder.LoopsInterleaved = CodeGenOpts.UnrollLoops;
587   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
588   PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
589   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
590   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
591 
592   MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
593 
594   if (TM)
595     TM->adjustPassManager(PMBuilder);
596 
597   if (CodeGenOpts.DebugInfoForProfiling ||
598       !CodeGenOpts.SampleProfileFile.empty())
599     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
600                            addAddDiscriminatorsPass);
601 
602   // In ObjC ARC mode, add the main ARC optimization passes.
603   if (LangOpts.ObjCAutoRefCount) {
604     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
605                            addObjCARCExpandPass);
606     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
607                            addObjCARCAPElimPass);
608     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
609                            addObjCARCOptPass);
610   }
611 
612   if (LangOpts.Coroutines)
613     addCoroutinePassesToExtensionPoints(PMBuilder);
614 
615   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
616     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
617                            addBoundsCheckingPass);
618     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
619                            addBoundsCheckingPass);
620   }
621 
622   if (CodeGenOpts.SanitizeCoverageType ||
623       CodeGenOpts.SanitizeCoverageIndirectCalls ||
624       CodeGenOpts.SanitizeCoverageTraceCmp) {
625     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
626                            addSanitizerCoveragePass);
627     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
628                            addSanitizerCoveragePass);
629   }
630 
631   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
632     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
633                            addAddressSanitizerPasses);
634     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
635                            addAddressSanitizerPasses);
636   }
637 
638   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
639     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
640                            addKernelAddressSanitizerPasses);
641     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
642                            addKernelAddressSanitizerPasses);
643   }
644 
645   if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
646     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
647                            addHWAddressSanitizerPasses);
648     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
649                            addHWAddressSanitizerPasses);
650   }
651 
652   if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
653     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
654                            addKernelHWAddressSanitizerPasses);
655     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
656                            addKernelHWAddressSanitizerPasses);
657   }
658 
659   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
660     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
661                            addMemorySanitizerPass);
662     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
663                            addMemorySanitizerPass);
664   }
665 
666   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
667     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
668                            addKernelMemorySanitizerPass);
669     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
670                            addKernelMemorySanitizerPass);
671   }
672 
673   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
674     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
675                            addThreadSanitizerPass);
676     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
677                            addThreadSanitizerPass);
678   }
679 
680   if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
681     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
682                            addDataFlowSanitizerPass);
683     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
684                            addDataFlowSanitizerPass);
685   }
686 
687   // Set up the per-function pass manager.
688   FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
689   if (CodeGenOpts.VerifyModule)
690     FPM.add(createVerifierPass());
691 
692   // Set up the per-module pass manager.
693   if (!CodeGenOpts.RewriteMapFiles.empty())
694     addSymbolRewriterPass(CodeGenOpts, &MPM);
695 
696   if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts)) {
697     MPM.add(createGCOVProfilerPass(*Options));
698     if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
699       MPM.add(createStripSymbolsPass(true));
700   }
701 
702   if (Optional<InstrProfOptions> Options =
703           getInstrProfOptions(CodeGenOpts, LangOpts))
704     MPM.add(createInstrProfilingLegacyPass(*Options, false));
705 
706   bool hasIRInstr = false;
707   if (CodeGenOpts.hasProfileIRInstr()) {
708     PMBuilder.EnablePGOInstrGen = true;
709     hasIRInstr = true;
710   }
711   if (CodeGenOpts.hasProfileCSIRInstr()) {
712     assert(!CodeGenOpts.hasProfileCSIRUse() &&
713            "Cannot have both CSProfileUse pass and CSProfileGen pass at the "
714            "same time");
715     assert(!hasIRInstr &&
716            "Cannot have both ProfileGen pass and CSProfileGen pass at the "
717            "same time");
718     PMBuilder.EnablePGOCSInstrGen = true;
719     hasIRInstr = true;
720   }
721   if (hasIRInstr) {
722     if (!CodeGenOpts.InstrProfileOutput.empty())
723       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
724     else
725       PMBuilder.PGOInstrGen = DefaultProfileGenName;
726   }
727   if (CodeGenOpts.hasProfileIRUse()) {
728     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
729     PMBuilder.EnablePGOCSInstrUse = CodeGenOpts.hasProfileCSIRUse();
730   }
731 
732   if (!CodeGenOpts.SampleProfileFile.empty())
733     PMBuilder.PGOSampleUse = CodeGenOpts.SampleProfileFile;
734 
735   PMBuilder.populateFunctionPassManager(FPM);
736   PMBuilder.populateModulePassManager(MPM);
737 }
738 
739 static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) {
740   SmallVector<const char *, 16> BackendArgs;
741   BackendArgs.push_back("clang"); // Fake program name.
742   if (!CodeGenOpts.DebugPass.empty()) {
743     BackendArgs.push_back("-debug-pass");
744     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
745   }
746   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
747     BackendArgs.push_back("-limit-float-precision");
748     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
749   }
750   BackendArgs.push_back(nullptr);
751   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
752                                     BackendArgs.data());
753 }
754 
755 void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
756   // Create the TargetMachine for generating code.
757   std::string Error;
758   std::string Triple = TheModule->getTargetTriple();
759   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
760   if (!TheTarget) {
761     if (MustCreateTM)
762       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
763     return;
764   }
765 
766   Optional<llvm::CodeModel::Model> CM = getCodeModel(CodeGenOpts);
767   std::string FeaturesStr =
768       llvm::join(TargetOpts.Features.begin(), TargetOpts.Features.end(), ",");
769   llvm::Reloc::Model RM = CodeGenOpts.RelocationModel;
770   CodeGenOpt::Level OptLevel = getCGOptLevel(CodeGenOpts);
771 
772   llvm::TargetOptions Options;
773   initTargetOptions(Options, CodeGenOpts, TargetOpts, LangOpts, HSOpts);
774   TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
775                                           Options, RM, CM, OptLevel));
776 }
777 
778 bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
779                                        BackendAction Action,
780                                        raw_pwrite_stream &OS,
781                                        raw_pwrite_stream *DwoOS) {
782   // Add LibraryInfo.
783   llvm::Triple TargetTriple(TheModule->getTargetTriple());
784   std::unique_ptr<TargetLibraryInfoImpl> TLII(
785       createTLII(TargetTriple, CodeGenOpts));
786   CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
787 
788   // Normal mode, emit a .s or .o file by running the code generator. Note,
789   // this also adds codegenerator level optimization passes.
790   TargetMachine::CodeGenFileType CGFT = getCodeGenFileType(Action);
791 
792   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
793   // "codegen" passes so that it isn't run multiple times when there is
794   // inlining happening.
795   if (CodeGenOpts.OptimizationLevel > 0)
796     CodeGenPasses.add(createObjCARCContractPass());
797 
798   if (TM->addPassesToEmitFile(CodeGenPasses, OS, DwoOS, CGFT,
799                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
800     Diags.Report(diag::err_fe_unable_to_interface_with_target);
801     return false;
802   }
803 
804   return true;
805 }
806 
807 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
808                                       std::unique_ptr<raw_pwrite_stream> OS) {
809   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
810 
811   setCommandLineOpts(CodeGenOpts);
812 
813   bool UsesCodeGen = (Action != Backend_EmitNothing &&
814                       Action != Backend_EmitBC &&
815                       Action != Backend_EmitLL);
816   CreateTargetMachine(UsesCodeGen);
817 
818   if (UsesCodeGen && !TM)
819     return;
820   if (TM)
821     TheModule->setDataLayout(TM->createDataLayout());
822 
823   legacy::PassManager PerModulePasses;
824   PerModulePasses.add(
825       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
826 
827   legacy::FunctionPassManager PerFunctionPasses(TheModule);
828   PerFunctionPasses.add(
829       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
830 
831   CreatePasses(PerModulePasses, PerFunctionPasses);
832 
833   legacy::PassManager CodeGenPasses;
834   CodeGenPasses.add(
835       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
836 
837   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
838 
839   switch (Action) {
840   case Backend_EmitNothing:
841     break;
842 
843   case Backend_EmitBC:
844     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
845       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
846         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
847         if (!ThinLinkOS)
848           return;
849       }
850       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
851                                CodeGenOpts.EnableSplitLTOUnit);
852       PerModulePasses.add(createWriteThinLTOBitcodePass(
853           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
854     } else {
855       // Emit a module summary by default for Regular LTO except for ld64
856       // targets
857       bool EmitLTOSummary =
858           (CodeGenOpts.PrepareForLTO &&
859            !CodeGenOpts.DisableLLVMPasses &&
860            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
861                llvm::Triple::Apple);
862       if (EmitLTOSummary) {
863         if (!TheModule->getModuleFlag("ThinLTO"))
864           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
865         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
866                                  uint32_t(1));
867       }
868 
869       PerModulePasses.add(createBitcodeWriterPass(
870           *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
871     }
872     break;
873 
874   case Backend_EmitLL:
875     PerModulePasses.add(
876         createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
877     break;
878 
879   default:
880     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
881       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
882       if (!DwoOS)
883         return;
884     }
885     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
886                        DwoOS ? &DwoOS->os() : nullptr))
887       return;
888   }
889 
890   // Before executing passes, print the final values of the LLVM options.
891   cl::PrintOptionValues();
892 
893   // Run passes. For now we do all passes at once, but eventually we
894   // would like to have the option of streaming code generation.
895 
896   {
897     PrettyStackTraceString CrashInfo("Per-function optimization");
898     llvm::TimeTraceScope TimeScope("PerFunctionPasses", StringRef(""));
899 
900     PerFunctionPasses.doInitialization();
901     for (Function &F : *TheModule)
902       if (!F.isDeclaration())
903         PerFunctionPasses.run(F);
904     PerFunctionPasses.doFinalization();
905   }
906 
907   {
908     PrettyStackTraceString CrashInfo("Per-module optimization passes");
909     llvm::TimeTraceScope TimeScope("PerModulePasses", StringRef(""));
910     PerModulePasses.run(*TheModule);
911   }
912 
913   {
914     PrettyStackTraceString CrashInfo("Code generation");
915     llvm::TimeTraceScope TimeScope("CodeGenPasses", StringRef(""));
916     CodeGenPasses.run(*TheModule);
917   }
918 
919   if (ThinLinkOS)
920     ThinLinkOS->keep();
921   if (DwoOS)
922     DwoOS->keep();
923 }
924 
925 static PassBuilder::OptimizationLevel mapToLevel(const CodeGenOptions &Opts) {
926   switch (Opts.OptimizationLevel) {
927   default:
928     llvm_unreachable("Invalid optimization level!");
929 
930   case 1:
931     return PassBuilder::O1;
932 
933   case 2:
934     switch (Opts.OptimizeSize) {
935     default:
936       llvm_unreachable("Invalid optimization level for size!");
937 
938     case 0:
939       return PassBuilder::O2;
940 
941     case 1:
942       return PassBuilder::Os;
943 
944     case 2:
945       return PassBuilder::Oz;
946     }
947 
948   case 3:
949     return PassBuilder::O3;
950   }
951 }
952 
953 static void addSanitizersAtO0(ModulePassManager &MPM,
954                               const Triple &TargetTriple,
955                               const LangOptions &LangOpts,
956                               const CodeGenOptions &CodeGenOpts) {
957   auto ASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
958     MPM.addPass(RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
959     bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
960     MPM.addPass(createModuleToFunctionPassAdaptor(AddressSanitizerPass(
961         CompileKernel, Recover, CodeGenOpts.SanitizeAddressUseAfterScope)));
962     bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
963     MPM.addPass(
964         ModuleAddressSanitizerPass(CompileKernel, Recover, ModuleUseAfterScope,
965                                    CodeGenOpts.SanitizeAddressUseOdrIndicator));
966   };
967 
968   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
969     ASanPass(SanitizerKind::Address, /*CompileKernel=*/false);
970   }
971 
972   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
973     ASanPass(SanitizerKind::KernelAddress, /*CompileKernel=*/true);
974   }
975 
976   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
977     MPM.addPass(MemorySanitizerPass({}));
978     MPM.addPass(createModuleToFunctionPassAdaptor(MemorySanitizerPass({})));
979   }
980 
981   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
982     MPM.addPass(createModuleToFunctionPassAdaptor(
983         MemorySanitizerPass({0, false, /*Kernel=*/true})));
984   }
985 
986   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
987     MPM.addPass(ThreadSanitizerPass());
988     MPM.addPass(createModuleToFunctionPassAdaptor(ThreadSanitizerPass()));
989   }
990 }
991 
992 /// A clean version of `EmitAssembly` that uses the new pass manager.
993 ///
994 /// Not all features are currently supported in this system, but where
995 /// necessary it falls back to the legacy pass manager to at least provide
996 /// basic functionality.
997 ///
998 /// This API is planned to have its functionality finished and then to replace
999 /// `EmitAssembly` at some point in the future when the default switches.
1000 void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
1001     BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
1002   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
1003   setCommandLineOpts(CodeGenOpts);
1004 
1005   bool RequiresCodeGen = (Action != Backend_EmitNothing &&
1006                           Action != Backend_EmitBC &&
1007                           Action != Backend_EmitLL);
1008   CreateTargetMachine(RequiresCodeGen);
1009 
1010   if (RequiresCodeGen && !TM)
1011     return;
1012   if (TM)
1013     TheModule->setDataLayout(TM->createDataLayout());
1014 
1015   Optional<PGOOptions> PGOOpt;
1016 
1017   if (CodeGenOpts.hasProfileIRInstr())
1018     // -fprofile-generate.
1019     PGOOpt = PGOOptions(CodeGenOpts.InstrProfileOutput.empty()
1020                             ? DefaultProfileGenName
1021                             : CodeGenOpts.InstrProfileOutput,
1022                         "", "", PGOOptions::IRInstr, PGOOptions::NoCSAction,
1023                         CodeGenOpts.DebugInfoForProfiling);
1024   else if (CodeGenOpts.hasProfileIRUse()) {
1025     // -fprofile-use.
1026     auto CSAction = CodeGenOpts.hasProfileCSIRUse() ? PGOOptions::CSIRUse
1027                                                     : PGOOptions::NoCSAction;
1028     PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "",
1029                         CodeGenOpts.ProfileRemappingFile, PGOOptions::IRUse,
1030                         CSAction, CodeGenOpts.DebugInfoForProfiling);
1031   } else if (!CodeGenOpts.SampleProfileFile.empty())
1032     // -fprofile-sample-use
1033     PGOOpt =
1034         PGOOptions(CodeGenOpts.SampleProfileFile, "",
1035                    CodeGenOpts.ProfileRemappingFile, PGOOptions::SampleUse,
1036                    PGOOptions::NoCSAction, CodeGenOpts.DebugInfoForProfiling);
1037   else if (CodeGenOpts.DebugInfoForProfiling)
1038     // -fdebug-info-for-profiling
1039     PGOOpt = PGOOptions("", "", "", PGOOptions::NoAction,
1040                         PGOOptions::NoCSAction, true);
1041 
1042   // Check to see if we want to generate a CS profile.
1043   if (CodeGenOpts.hasProfileCSIRInstr()) {
1044     assert(!CodeGenOpts.hasProfileCSIRUse() &&
1045            "Cannot have both CSProfileUse pass and CSProfileGen pass at "
1046            "the same time");
1047     if (PGOOpt.hasValue()) {
1048       assert(PGOOpt->Action != PGOOptions::IRInstr &&
1049              PGOOpt->Action != PGOOptions::SampleUse &&
1050              "Cannot run CSProfileGen pass with ProfileGen or SampleUse "
1051              " pass");
1052       PGOOpt->CSProfileGenFile = CodeGenOpts.InstrProfileOutput.empty()
1053                                      ? DefaultProfileGenName
1054                                      : CodeGenOpts.InstrProfileOutput;
1055       PGOOpt->CSAction = PGOOptions::CSIRInstr;
1056     } else
1057       PGOOpt = PGOOptions("",
1058                           CodeGenOpts.InstrProfileOutput.empty()
1059                               ? DefaultProfileGenName
1060                               : CodeGenOpts.InstrProfileOutput,
1061                           "", PGOOptions::NoAction, PGOOptions::CSIRInstr,
1062                           CodeGenOpts.DebugInfoForProfiling);
1063   }
1064 
1065   PipelineTuningOptions PTO;
1066   PTO.LoopUnrolling = CodeGenOpts.UnrollLoops;
1067   // For historical reasons, loop interleaving is set to mirror setting for loop
1068   // unrolling.
1069   PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
1070   PTO.LoopVectorization = CodeGenOpts.VectorizeLoop;
1071   PTO.SLPVectorization = CodeGenOpts.VectorizeSLP;
1072 
1073   PassInstrumentationCallbacks PIC;
1074   StandardInstrumentations SI;
1075   SI.registerCallbacks(PIC);
1076   PassBuilder PB(TM.get(), PTO, PGOOpt, &PIC);
1077 
1078   // Attempt to load pass plugins and register their callbacks with PB.
1079   for (auto &PluginFN : CodeGenOpts.PassPlugins) {
1080     auto PassPlugin = PassPlugin::Load(PluginFN);
1081     if (PassPlugin) {
1082       PassPlugin->registerPassBuilderCallbacks(PB);
1083     } else {
1084       Diags.Report(diag::err_fe_unable_to_load_plugin)
1085           << PluginFN << toString(PassPlugin.takeError());
1086     }
1087   }
1088 
1089   LoopAnalysisManager LAM(CodeGenOpts.DebugPassManager);
1090   FunctionAnalysisManager FAM(CodeGenOpts.DebugPassManager);
1091   CGSCCAnalysisManager CGAM(CodeGenOpts.DebugPassManager);
1092   ModuleAnalysisManager MAM(CodeGenOpts.DebugPassManager);
1093 
1094   // Register the AA manager first so that our version is the one used.
1095   FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
1096 
1097   // Register the target library analysis directly and give it a customized
1098   // preset TLI.
1099   Triple TargetTriple(TheModule->getTargetTriple());
1100   std::unique_ptr<TargetLibraryInfoImpl> TLII(
1101       createTLII(TargetTriple, CodeGenOpts));
1102   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
1103 
1104   // Register all the basic analyses with the managers.
1105   PB.registerModuleAnalyses(MAM);
1106   PB.registerCGSCCAnalyses(CGAM);
1107   PB.registerFunctionAnalyses(FAM);
1108   PB.registerLoopAnalyses(LAM);
1109   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
1110 
1111   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
1112 
1113   if (!CodeGenOpts.DisableLLVMPasses) {
1114     bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
1115     bool IsLTO = CodeGenOpts.PrepareForLTO;
1116 
1117     if (CodeGenOpts.OptimizationLevel == 0) {
1118       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1119         MPM.addPass(GCOVProfilerPass(*Options));
1120       if (Optional<InstrProfOptions> Options =
1121               getInstrProfOptions(CodeGenOpts, LangOpts))
1122         MPM.addPass(InstrProfiling(*Options, false));
1123 
1124       // Build a minimal pipeline based on the semantics required by Clang,
1125       // which is just that always inlining occurs. Further, disable generating
1126       // lifetime intrinsics to avoid enabling further optimizations during
1127       // code generation.
1128       MPM.addPass(AlwaysInlinerPass(/*InsertLifetimeIntrinsics=*/false));
1129 
1130       // At -O0, we can still do PGO. Add all the requested passes for
1131       // instrumentation PGO, if requested.
1132       if (PGOOpt && (PGOOpt->Action == PGOOptions::IRInstr ||
1133                      PGOOpt->Action == PGOOptions::IRUse))
1134         PB.addPGOInstrPassesForO0(
1135             MPM, CodeGenOpts.DebugPassManager,
1136             /* RunProfileGen */ (PGOOpt->Action == PGOOptions::IRInstr),
1137             /* IsCS */ false, PGOOpt->ProfileFile,
1138             PGOOpt->ProfileRemappingFile);
1139 
1140       // At -O0 we directly run necessary sanitizer passes.
1141       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1142         MPM.addPass(createModuleToFunctionPassAdaptor(BoundsCheckingPass()));
1143 
1144       // Lastly, add semantically necessary passes for LTO.
1145       if (IsLTO || IsThinLTO) {
1146         MPM.addPass(CanonicalizeAliasesPass());
1147         MPM.addPass(NameAnonGlobalPass());
1148       }
1149     } else {
1150       // Map our optimization levels into one of the distinct levels used to
1151       // configure the pipeline.
1152       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
1153 
1154       PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1155         MPM.addPass(createModuleToFunctionPassAdaptor(
1156             EntryExitInstrumenterPass(/*PostInlining=*/false)));
1157       });
1158 
1159       // Register callbacks to schedule sanitizer passes at the appropriate part of
1160       // the pipeline.
1161       // FIXME: either handle asan/the remaining sanitizers or error out
1162       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1163         PB.registerScalarOptimizerLateEPCallback(
1164             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1165               FPM.addPass(BoundsCheckingPass());
1166             });
1167       if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
1168         PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1169           MPM.addPass(MemorySanitizerPass({}));
1170         });
1171         PB.registerOptimizerLastEPCallback(
1172             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1173               FPM.addPass(MemorySanitizerPass({}));
1174             });
1175       }
1176       if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
1177         PB.registerPipelineStartEPCallback(
1178             [](ModulePassManager &MPM) { MPM.addPass(ThreadSanitizerPass()); });
1179         PB.registerOptimizerLastEPCallback(
1180             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1181               FPM.addPass(ThreadSanitizerPass());
1182             });
1183       }
1184       if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
1185         PB.registerPipelineStartEPCallback([&](ModulePassManager &MPM) {
1186           MPM.addPass(
1187               RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
1188         });
1189         bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::Address);
1190         bool UseAfterScope = CodeGenOpts.SanitizeAddressUseAfterScope;
1191         PB.registerOptimizerLastEPCallback(
1192             [Recover, UseAfterScope](FunctionPassManager &FPM,
1193                                      PassBuilder::OptimizationLevel Level) {
1194               FPM.addPass(AddressSanitizerPass(
1195                   /*CompileKernel=*/false, Recover, UseAfterScope));
1196             });
1197         bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
1198         bool UseOdrIndicator = CodeGenOpts.SanitizeAddressUseOdrIndicator;
1199         PB.registerPipelineStartEPCallback(
1200             [Recover, ModuleUseAfterScope,
1201              UseOdrIndicator](ModulePassManager &MPM) {
1202               MPM.addPass(ModuleAddressSanitizerPass(
1203                   /*CompileKernel=*/false, Recover, ModuleUseAfterScope,
1204                   UseOdrIndicator));
1205             });
1206       }
1207       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1208         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1209           MPM.addPass(GCOVProfilerPass(*Options));
1210         });
1211       if (Optional<InstrProfOptions> Options =
1212               getInstrProfOptions(CodeGenOpts, LangOpts))
1213         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1214           MPM.addPass(InstrProfiling(*Options, false));
1215         });
1216 
1217       if (IsThinLTO) {
1218         MPM = PB.buildThinLTOPreLinkDefaultPipeline(
1219             Level, CodeGenOpts.DebugPassManager);
1220         MPM.addPass(CanonicalizeAliasesPass());
1221         MPM.addPass(NameAnonGlobalPass());
1222       } else if (IsLTO) {
1223         MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
1224                                                 CodeGenOpts.DebugPassManager);
1225         MPM.addPass(CanonicalizeAliasesPass());
1226         MPM.addPass(NameAnonGlobalPass());
1227       } else {
1228         MPM = PB.buildPerModuleDefaultPipeline(Level,
1229                                                CodeGenOpts.DebugPassManager);
1230       }
1231     }
1232 
1233     if (CodeGenOpts.SanitizeCoverageType ||
1234         CodeGenOpts.SanitizeCoverageIndirectCalls ||
1235         CodeGenOpts.SanitizeCoverageTraceCmp) {
1236       auto SancovOpts = getSancovOptsFromCGOpts(CodeGenOpts);
1237       MPM.addPass(ModuleSanitizerCoveragePass(SancovOpts));
1238     }
1239 
1240     if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
1241       bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
1242       MPM.addPass(HWAddressSanitizerPass(
1243           /*CompileKernel=*/false, Recover));
1244     }
1245     if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
1246       MPM.addPass(HWAddressSanitizerPass(
1247           /*CompileKernel=*/true, /*Recover=*/true));
1248     }
1249 
1250     if (CodeGenOpts.OptimizationLevel == 0) {
1251       addSanitizersAtO0(MPM, TargetTriple, LangOpts, CodeGenOpts);
1252     }
1253   }
1254 
1255   // FIXME: We still use the legacy pass manager to do code generation. We
1256   // create that pass manager here and use it as needed below.
1257   legacy::PassManager CodeGenPasses;
1258   bool NeedCodeGen = false;
1259   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
1260 
1261   // Append any output we need to the pass manager.
1262   switch (Action) {
1263   case Backend_EmitNothing:
1264     break;
1265 
1266   case Backend_EmitBC:
1267     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
1268       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
1269         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
1270         if (!ThinLinkOS)
1271           return;
1272       }
1273       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1274                                CodeGenOpts.EnableSplitLTOUnit);
1275       MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
1276                                                            : nullptr));
1277     } else {
1278       // Emit a module summary by default for Regular LTO except for ld64
1279       // targets
1280       bool EmitLTOSummary =
1281           (CodeGenOpts.PrepareForLTO &&
1282            !CodeGenOpts.DisableLLVMPasses &&
1283            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
1284                llvm::Triple::Apple);
1285       if (EmitLTOSummary) {
1286         if (!TheModule->getModuleFlag("ThinLTO"))
1287           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
1288         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1289                                  uint32_t(1));
1290       }
1291       MPM.addPass(
1292           BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
1293     }
1294     break;
1295 
1296   case Backend_EmitLL:
1297     MPM.addPass(PrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
1298     break;
1299 
1300   case Backend_EmitAssembly:
1301   case Backend_EmitMCNull:
1302   case Backend_EmitObj:
1303     NeedCodeGen = true;
1304     CodeGenPasses.add(
1305         createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
1306     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
1307       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
1308       if (!DwoOS)
1309         return;
1310     }
1311     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
1312                        DwoOS ? &DwoOS->os() : nullptr))
1313       // FIXME: Should we handle this error differently?
1314       return;
1315     break;
1316   }
1317 
1318   // Before executing passes, print the final values of the LLVM options.
1319   cl::PrintOptionValues();
1320 
1321   // Now that we have all of the passes ready, run them.
1322   {
1323     PrettyStackTraceString CrashInfo("Optimizer");
1324     MPM.run(*TheModule, MAM);
1325   }
1326 
1327   // Now if needed, run the legacy PM for codegen.
1328   if (NeedCodeGen) {
1329     PrettyStackTraceString CrashInfo("Code generation");
1330     CodeGenPasses.run(*TheModule);
1331   }
1332 
1333   if (ThinLinkOS)
1334     ThinLinkOS->keep();
1335   if (DwoOS)
1336     DwoOS->keep();
1337 }
1338 
1339 Expected<BitcodeModule> clang::FindThinLTOModule(MemoryBufferRef MBRef) {
1340   Expected<std::vector<BitcodeModule>> BMsOrErr = getBitcodeModuleList(MBRef);
1341   if (!BMsOrErr)
1342     return BMsOrErr.takeError();
1343 
1344   // The bitcode file may contain multiple modules, we want the one that is
1345   // marked as being the ThinLTO module.
1346   if (const BitcodeModule *Bm = FindThinLTOModule(*BMsOrErr))
1347     return *Bm;
1348 
1349   return make_error<StringError>("Could not find module summary",
1350                                  inconvertibleErrorCode());
1351 }
1352 
1353 BitcodeModule *clang::FindThinLTOModule(MutableArrayRef<BitcodeModule> BMs) {
1354   for (BitcodeModule &BM : BMs) {
1355     Expected<BitcodeLTOInfo> LTOInfo = BM.getLTOInfo();
1356     if (LTOInfo && LTOInfo->IsThinLTO)
1357       return &BM;
1358   }
1359   return nullptr;
1360 }
1361 
1362 static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
1363                               const HeaderSearchOptions &HeaderOpts,
1364                               const CodeGenOptions &CGOpts,
1365                               const clang::TargetOptions &TOpts,
1366                               const LangOptions &LOpts,
1367                               std::unique_ptr<raw_pwrite_stream> OS,
1368                               std::string SampleProfile,
1369                               std::string ProfileRemapping,
1370                               BackendAction Action) {
1371   StringMap<DenseMap<GlobalValue::GUID, GlobalValueSummary *>>
1372       ModuleToDefinedGVSummaries;
1373   CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
1374 
1375   setCommandLineOpts(CGOpts);
1376 
1377   // We can simply import the values mentioned in the combined index, since
1378   // we should only invoke this using the individual indexes written out
1379   // via a WriteIndexesThinBackend.
1380   FunctionImporter::ImportMapTy ImportList;
1381   for (auto &GlobalList : *CombinedIndex) {
1382     // Ignore entries for undefined references.
1383     if (GlobalList.second.SummaryList.empty())
1384       continue;
1385 
1386     auto GUID = GlobalList.first;
1387     for (auto &Summary : GlobalList.second.SummaryList) {
1388       // Skip the summaries for the importing module. These are included to
1389       // e.g. record required linkage changes.
1390       if (Summary->modulePath() == M->getModuleIdentifier())
1391         continue;
1392       // Add an entry to provoke importing by thinBackend.
1393       ImportList[Summary->modulePath()].insert(GUID);
1394     }
1395   }
1396 
1397   std::vector<std::unique_ptr<llvm::MemoryBuffer>> OwnedImports;
1398   MapVector<llvm::StringRef, llvm::BitcodeModule> ModuleMap;
1399 
1400   for (auto &I : ImportList) {
1401     ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> MBOrErr =
1402         llvm::MemoryBuffer::getFile(I.first());
1403     if (!MBOrErr) {
1404       errs() << "Error loading imported file '" << I.first()
1405              << "': " << MBOrErr.getError().message() << "\n";
1406       return;
1407     }
1408 
1409     Expected<BitcodeModule> BMOrErr = FindThinLTOModule(**MBOrErr);
1410     if (!BMOrErr) {
1411       handleAllErrors(BMOrErr.takeError(), [&](ErrorInfoBase &EIB) {
1412         errs() << "Error loading imported file '" << I.first()
1413                << "': " << EIB.message() << '\n';
1414       });
1415       return;
1416     }
1417     ModuleMap.insert({I.first(), *BMOrErr});
1418 
1419     OwnedImports.push_back(std::move(*MBOrErr));
1420   }
1421   auto AddStream = [&](size_t Task) {
1422     return std::make_unique<lto::NativeObjectStream>(std::move(OS));
1423   };
1424   lto::Config Conf;
1425   if (CGOpts.SaveTempsFilePrefix != "") {
1426     if (Error E = Conf.addSaveTemps(CGOpts.SaveTempsFilePrefix + ".",
1427                                     /* UseInputModulePath */ false)) {
1428       handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1429         errs() << "Error setting up ThinLTO save-temps: " << EIB.message()
1430                << '\n';
1431       });
1432     }
1433   }
1434   Conf.CPU = TOpts.CPU;
1435   Conf.CodeModel = getCodeModel(CGOpts);
1436   Conf.MAttrs = TOpts.Features;
1437   Conf.RelocModel = CGOpts.RelocationModel;
1438   Conf.CGOptLevel = getCGOptLevel(CGOpts);
1439   Conf.OptLevel = CGOpts.OptimizationLevel;
1440   initTargetOptions(Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
1441   Conf.SampleProfile = std::move(SampleProfile);
1442 
1443   // Context sensitive profile.
1444   if (CGOpts.hasProfileCSIRInstr()) {
1445     Conf.RunCSIRInstr = true;
1446     Conf.CSIRProfile = std::move(CGOpts.InstrProfileOutput);
1447   } else if (CGOpts.hasProfileCSIRUse()) {
1448     Conf.RunCSIRInstr = false;
1449     Conf.CSIRProfile = std::move(CGOpts.ProfileInstrumentUsePath);
1450   }
1451 
1452   Conf.ProfileRemapping = std::move(ProfileRemapping);
1453   Conf.UseNewPM = CGOpts.ExperimentalNewPassManager;
1454   Conf.DebugPassManager = CGOpts.DebugPassManager;
1455   Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
1456   Conf.RemarksFilename = CGOpts.OptRecordFile;
1457   Conf.RemarksPasses = CGOpts.OptRecordPasses;
1458   Conf.RemarksFormat = CGOpts.OptRecordFormat;
1459   Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
1460   Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
1461   switch (Action) {
1462   case Backend_EmitNothing:
1463     Conf.PreCodeGenModuleHook = [](size_t Task, const Module &Mod) {
1464       return false;
1465     };
1466     break;
1467   case Backend_EmitLL:
1468     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1469       M->print(*OS, nullptr, CGOpts.EmitLLVMUseLists);
1470       return false;
1471     };
1472     break;
1473   case Backend_EmitBC:
1474     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1475       WriteBitcodeToFile(*M, *OS, CGOpts.EmitLLVMUseLists);
1476       return false;
1477     };
1478     break;
1479   default:
1480     Conf.CGFileType = getCodeGenFileType(Action);
1481     break;
1482   }
1483   if (Error E = thinBackend(
1484           Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
1485           ModuleToDefinedGVSummaries[M->getModuleIdentifier()], ModuleMap)) {
1486     handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1487       errs() << "Error running ThinLTO backend: " << EIB.message() << '\n';
1488     });
1489   }
1490 }
1491 
1492 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
1493                               const HeaderSearchOptions &HeaderOpts,
1494                               const CodeGenOptions &CGOpts,
1495                               const clang::TargetOptions &TOpts,
1496                               const LangOptions &LOpts,
1497                               const llvm::DataLayout &TDesc, Module *M,
1498                               BackendAction Action,
1499                               std::unique_ptr<raw_pwrite_stream> OS) {
1500 
1501   llvm::TimeTraceScope TimeScope("Backend", StringRef(""));
1502 
1503   std::unique_ptr<llvm::Module> EmptyModule;
1504   if (!CGOpts.ThinLTOIndexFile.empty()) {
1505     // If we are performing a ThinLTO importing compile, load the function index
1506     // into memory and pass it into runThinLTOBackend, which will run the
1507     // function importer and invoke LTO passes.
1508     Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
1509         llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile,
1510                                            /*IgnoreEmptyThinLTOIndexFile*/true);
1511     if (!IndexOrErr) {
1512       logAllUnhandledErrors(IndexOrErr.takeError(), errs(),
1513                             "Error loading index file '" +
1514                             CGOpts.ThinLTOIndexFile + "': ");
1515       return;
1516     }
1517     std::unique_ptr<ModuleSummaryIndex> CombinedIndex = std::move(*IndexOrErr);
1518     // A null CombinedIndex means we should skip ThinLTO compilation
1519     // (LLVM will optionally ignore empty index files, returning null instead
1520     // of an error).
1521     if (CombinedIndex) {
1522       if (!CombinedIndex->skipModuleByDistributedBackend()) {
1523         runThinLTOBackend(CombinedIndex.get(), M, HeaderOpts, CGOpts, TOpts,
1524                           LOpts, std::move(OS), CGOpts.SampleProfileFile,
1525                           CGOpts.ProfileRemappingFile, Action);
1526         return;
1527       }
1528       // Distributed indexing detected that nothing from the module is needed
1529       // for the final linking. So we can skip the compilation. We sill need to
1530       // output an empty object file to make sure that a linker does not fail
1531       // trying to read it. Also for some features, like CFI, we must skip
1532       // the compilation as CombinedIndex does not contain all required
1533       // information.
1534       EmptyModule = std::make_unique<llvm::Module>("empty", M->getContext());
1535       EmptyModule->setTargetTriple(M->getTargetTriple());
1536       M = EmptyModule.get();
1537     }
1538   }
1539 
1540   EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
1541 
1542   if (CGOpts.ExperimentalNewPassManager)
1543     AsmHelper.EmitAssemblyWithNewPassManager(Action, std::move(OS));
1544   else
1545     AsmHelper.EmitAssembly(Action, std::move(OS));
1546 
1547   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
1548   // DataLayout.
1549   if (AsmHelper.TM) {
1550     std::string DLDesc = M->getDataLayout().getStringRepresentation();
1551     if (DLDesc != TDesc.getStringRepresentation()) {
1552       unsigned DiagID = Diags.getCustomDiagID(
1553           DiagnosticsEngine::Error, "backend data layout '%0' does not match "
1554                                     "expected target description '%1'");
1555       Diags.Report(DiagID) << DLDesc << TDesc.getStringRepresentation();
1556     }
1557   }
1558 }
1559 
1560 static const char* getSectionNameForBitcode(const Triple &T) {
1561   switch (T.getObjectFormat()) {
1562   case Triple::MachO:
1563     return "__LLVM,__bitcode";
1564   case Triple::COFF:
1565   case Triple::ELF:
1566   case Triple::Wasm:
1567   case Triple::UnknownObjectFormat:
1568     return ".llvmbc";
1569   case Triple::XCOFF:
1570     llvm_unreachable("XCOFF is not yet implemented");
1571     break;
1572   }
1573   llvm_unreachable("Unimplemented ObjectFormatType");
1574 }
1575 
1576 static const char* getSectionNameForCommandline(const Triple &T) {
1577   switch (T.getObjectFormat()) {
1578   case Triple::MachO:
1579     return "__LLVM,__cmdline";
1580   case Triple::COFF:
1581   case Triple::ELF:
1582   case Triple::Wasm:
1583   case Triple::UnknownObjectFormat:
1584     return ".llvmcmd";
1585   case Triple::XCOFF:
1586     llvm_unreachable("XCOFF is not yet implemented");
1587     break;
1588   }
1589   llvm_unreachable("Unimplemented ObjectFormatType");
1590 }
1591 
1592 // With -fembed-bitcode, save a copy of the llvm IR as data in the
1593 // __LLVM,__bitcode section.
1594 void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
1595                          llvm::MemoryBufferRef Buf) {
1596   if (CGOpts.getEmbedBitcode() == CodeGenOptions::Embed_Off)
1597     return;
1598 
1599   // Save llvm.compiler.used and remote it.
1600   SmallVector<Constant*, 2> UsedArray;
1601   SmallPtrSet<GlobalValue*, 4> UsedGlobals;
1602   Type *UsedElementType = Type::getInt8Ty(M->getContext())->getPointerTo(0);
1603   GlobalVariable *Used = collectUsedGlobalVariables(*M, UsedGlobals, true);
1604   for (auto *GV : UsedGlobals) {
1605     if (GV->getName() != "llvm.embedded.module" &&
1606         GV->getName() != "llvm.cmdline")
1607       UsedArray.push_back(
1608           ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
1609   }
1610   if (Used)
1611     Used->eraseFromParent();
1612 
1613   // Embed the bitcode for the llvm module.
1614   std::string Data;
1615   ArrayRef<uint8_t> ModuleData;
1616   Triple T(M->getTargetTriple());
1617   // Create a constant that contains the bitcode.
1618   // In case of embedding a marker, ignore the input Buf and use the empty
1619   // ArrayRef. It is also legal to create a bitcode marker even Buf is empty.
1620   if (CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Marker) {
1621     if (!isBitcode((const unsigned char *)Buf.getBufferStart(),
1622                    (const unsigned char *)Buf.getBufferEnd())) {
1623       // If the input is LLVM Assembly, bitcode is produced by serializing
1624       // the module. Use-lists order need to be perserved in this case.
1625       llvm::raw_string_ostream OS(Data);
1626       llvm::WriteBitcodeToFile(*M, OS, /* ShouldPreserveUseListOrder */ true);
1627       ModuleData =
1628           ArrayRef<uint8_t>((const uint8_t *)OS.str().data(), OS.str().size());
1629     } else
1630       // If the input is LLVM bitcode, write the input byte stream directly.
1631       ModuleData = ArrayRef<uint8_t>((const uint8_t *)Buf.getBufferStart(),
1632                                      Buf.getBufferSize());
1633   }
1634   llvm::Constant *ModuleConstant =
1635       llvm::ConstantDataArray::get(M->getContext(), ModuleData);
1636   llvm::GlobalVariable *GV = new llvm::GlobalVariable(
1637       *M, ModuleConstant->getType(), true, llvm::GlobalValue::PrivateLinkage,
1638       ModuleConstant);
1639   GV->setSection(getSectionNameForBitcode(T));
1640   UsedArray.push_back(
1641       ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
1642   if (llvm::GlobalVariable *Old =
1643           M->getGlobalVariable("llvm.embedded.module", true)) {
1644     assert(Old->hasOneUse() &&
1645            "llvm.embedded.module can only be used once in llvm.compiler.used");
1646     GV->takeName(Old);
1647     Old->eraseFromParent();
1648   } else {
1649     GV->setName("llvm.embedded.module");
1650   }
1651 
1652   // Skip if only bitcode needs to be embedded.
1653   if (CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Bitcode) {
1654     // Embed command-line options.
1655     ArrayRef<uint8_t> CmdData(const_cast<uint8_t *>(CGOpts.CmdArgs.data()),
1656                               CGOpts.CmdArgs.size());
1657     llvm::Constant *CmdConstant =
1658       llvm::ConstantDataArray::get(M->getContext(), CmdData);
1659     GV = new llvm::GlobalVariable(*M, CmdConstant->getType(), true,
1660                                   llvm::GlobalValue::PrivateLinkage,
1661                                   CmdConstant);
1662     GV->setSection(getSectionNameForCommandline(T));
1663     UsedArray.push_back(
1664         ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, UsedElementType));
1665     if (llvm::GlobalVariable *Old =
1666             M->getGlobalVariable("llvm.cmdline", true)) {
1667       assert(Old->hasOneUse() &&
1668              "llvm.cmdline can only be used once in llvm.compiler.used");
1669       GV->takeName(Old);
1670       Old->eraseFromParent();
1671     } else {
1672       GV->setName("llvm.cmdline");
1673     }
1674   }
1675 
1676   if (UsedArray.empty())
1677     return;
1678 
1679   // Recreate llvm.compiler.used.
1680   ArrayType *ATy = ArrayType::get(UsedElementType, UsedArray.size());
1681   auto *NewUsed = new GlobalVariable(
1682       *M, ATy, false, llvm::GlobalValue::AppendingLinkage,
1683       llvm::ConstantArray::get(ATy, UsedArray), "llvm.compiler.used");
1684   NewUsed->setSection("llvm.metadata");
1685 }
1686