xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/BackendUtil.cpp (revision d13def78ccef6dbc25c2e197089ee5fc4d7b82c3) 
1 //===--- BackendUtil.cpp - LLVM Backend Utilities -------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "clang/CodeGen/BackendUtil.h"
10 #include "clang/Basic/CodeGenOptions.h"
11 #include "clang/Basic/Diagnostic.h"
12 #include "clang/Basic/LangOptions.h"
13 #include "clang/Basic/TargetOptions.h"
14 #include "clang/Frontend/FrontendDiagnostic.h"
15 #include "clang/Frontend/Utils.h"
16 #include "clang/Lex/HeaderSearchOptions.h"
17 #include "llvm/ADT/SmallSet.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/ADT/StringSwitch.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/Analysis/TargetLibraryInfo.h"
22 #include "llvm/Analysis/TargetTransformInfo.h"
23 #include "llvm/Bitcode/BitcodeReader.h"
24 #include "llvm/Bitcode/BitcodeWriter.h"
25 #include "llvm/Bitcode/BitcodeWriterPass.h"
26 #include "llvm/CodeGen/RegAllocRegistry.h"
27 #include "llvm/CodeGen/SchedulerRegistry.h"
28 #include "llvm/CodeGen/TargetSubtargetInfo.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/IRPrintingPasses.h"
31 #include "llvm/IR/LegacyPassManager.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/ModuleSummaryIndex.h"
34 #include "llvm/IR/Verifier.h"
35 #include "llvm/LTO/LTOBackend.h"
36 #include "llvm/MC/MCAsmInfo.h"
37 #include "llvm/MC/SubtargetFeature.h"
38 #include "llvm/Passes/PassBuilder.h"
39 #include "llvm/Passes/PassPlugin.h"
40 #include "llvm/Passes/StandardInstrumentations.h"
41 #include "llvm/Support/BuryPointer.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/MemoryBuffer.h"
44 #include "llvm/Support/PrettyStackTrace.h"
45 #include "llvm/Support/TargetRegistry.h"
46 #include "llvm/Support/TimeProfiler.h"
47 #include "llvm/Support/Timer.h"
48 #include "llvm/Support/raw_ostream.h"
49 #include "llvm/Target/TargetMachine.h"
50 #include "llvm/Target/TargetOptions.h"
51 #include "llvm/Transforms/Coroutines.h"
52 #include "llvm/Transforms/IPO.h"
53 #include "llvm/Transforms/IPO/AlwaysInliner.h"
54 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
55 #include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
56 #include "llvm/Transforms/InstCombine/InstCombine.h"
57 #include "llvm/Transforms/Instrumentation.h"
58 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
59 #include "llvm/Transforms/Instrumentation/BoundsChecking.h"
60 #include "llvm/Transforms/Instrumentation/GCOVProfiler.h"
61 #include "llvm/Transforms/Instrumentation/HWAddressSanitizer.h"
62 #include "llvm/Transforms/Instrumentation/InstrProfiling.h"
63 #include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
64 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
65 #include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
66 #include "llvm/Transforms/ObjCARC.h"
67 #include "llvm/Transforms/Scalar.h"
68 #include "llvm/Transforms/Scalar/GVN.h"
69 #include "llvm/Transforms/Utils.h"
70 #include "llvm/Transforms/Utils/CanonicalizeAliases.h"
71 #include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
72 #include "llvm/Transforms/Utils/NameAnonGlobals.h"
73 #include "llvm/Transforms/Utils/SymbolRewriter.h"
74 #include <memory>
75 using namespace clang;
76 using namespace llvm;
77 
78 #define HANDLE_EXTENSION(Ext)                                                  \
79   llvm::PassPluginLibraryInfo get##Ext##PluginInfo();
80 #include "llvm/Support/Extension.def"
81 
82 namespace {
83 
84 // Default filename used for profile generation.
85 static constexpr StringLiteral DefaultProfileGenName = "default_%m.profraw";
86 
87 class EmitAssemblyHelper {
88   DiagnosticsEngine &Diags;
89   const HeaderSearchOptions &HSOpts;
90   const CodeGenOptions &CodeGenOpts;
91   const clang::TargetOptions &TargetOpts;
92   const LangOptions &LangOpts;
93   Module *TheModule;
94 
95   Timer CodeGenerationTime;
96 
97   std::unique_ptr<raw_pwrite_stream> OS;
98 
99   TargetIRAnalysis getTargetIRAnalysis() const {
100     if (TM)
101       return TM->getTargetIRAnalysis();
102 
103     return TargetIRAnalysis();
104   }
105 
106   void CreatePasses(legacy::PassManager &MPM, legacy::FunctionPassManager &FPM);
107 
108   /// Generates the TargetMachine.
109   /// Leaves TM unchanged if it is unable to create the target machine.
110   /// Some of our clang tests specify triples which are not built
111   /// into clang. This is okay because these tests check the generated
112   /// IR, and they require DataLayout which depends on the triple.
113   /// In this case, we allow this method to fail and not report an error.
114   /// When MustCreateTM is used, we print an error if we are unable to load
115   /// the requested target.
116   void CreateTargetMachine(bool MustCreateTM);
117 
118   /// Add passes necessary to emit assembly or LLVM IR.
119   ///
120   /// \return True on success.
121   bool AddEmitPasses(legacy::PassManager &CodeGenPasses, BackendAction Action,
122                      raw_pwrite_stream &OS, raw_pwrite_stream *DwoOS);
123 
124   std::unique_ptr<llvm::ToolOutputFile> openOutputFile(StringRef Path) {
125     std::error_code EC;
126     auto F = std::make_unique<llvm::ToolOutputFile>(Path, EC,
127                                                      llvm::sys::fs::OF_None);
128     if (EC) {
129       Diags.Report(diag::err_fe_unable_to_open_output) << Path << EC.message();
130       F.reset();
131     }
132     return F;
133   }
134 
135 public:
136   EmitAssemblyHelper(DiagnosticsEngine &_Diags,
137                      const HeaderSearchOptions &HeaderSearchOpts,
138                      const CodeGenOptions &CGOpts,
139                      const clang::TargetOptions &TOpts,
140                      const LangOptions &LOpts, Module *M)
141       : Diags(_Diags), HSOpts(HeaderSearchOpts), CodeGenOpts(CGOpts),
142         TargetOpts(TOpts), LangOpts(LOpts), TheModule(M),
143         CodeGenerationTime("codegen", "Code Generation Time") {}
144 
145   ~EmitAssemblyHelper() {
146     if (CodeGenOpts.DisableFree)
147       BuryPointer(std::move(TM));
148   }
149 
150   std::unique_ptr<TargetMachine> TM;
151 
152   void EmitAssembly(BackendAction Action,
153                     std::unique_ptr<raw_pwrite_stream> OS);
154 
155   void EmitAssemblyWithNewPassManager(BackendAction Action,
156                                       std::unique_ptr<raw_pwrite_stream> OS);
157 };
158 
159 // We need this wrapper to access LangOpts and CGOpts from extension functions
160 // that we add to the PassManagerBuilder.
161 class PassManagerBuilderWrapper : public PassManagerBuilder {
162 public:
163   PassManagerBuilderWrapper(const Triple &TargetTriple,
164                             const CodeGenOptions &CGOpts,
165                             const LangOptions &LangOpts)
166       : PassManagerBuilder(), TargetTriple(TargetTriple), CGOpts(CGOpts),
167         LangOpts(LangOpts) {}
168   const Triple &getTargetTriple() const { return TargetTriple; }
169   const CodeGenOptions &getCGOpts() const { return CGOpts; }
170   const LangOptions &getLangOpts() const { return LangOpts; }
171 
172 private:
173   const Triple &TargetTriple;
174   const CodeGenOptions &CGOpts;
175   const LangOptions &LangOpts;
176 };
177 }
178 
179 static void addObjCARCAPElimPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
180   if (Builder.OptLevel > 0)
181     PM.add(createObjCARCAPElimPass());
182 }
183 
184 static void addObjCARCExpandPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
185   if (Builder.OptLevel > 0)
186     PM.add(createObjCARCExpandPass());
187 }
188 
189 static void addObjCARCOptPass(const PassManagerBuilder &Builder, PassManagerBase &PM) {
190   if (Builder.OptLevel > 0)
191     PM.add(createObjCARCOptPass());
192 }
193 
194 static void addAddDiscriminatorsPass(const PassManagerBuilder &Builder,
195                                      legacy::PassManagerBase &PM) {
196   PM.add(createAddDiscriminatorsPass());
197 }
198 
199 static void addBoundsCheckingPass(const PassManagerBuilder &Builder,
200                                   legacy::PassManagerBase &PM) {
201   PM.add(createBoundsCheckingLegacyPass());
202 }
203 
204 static SanitizerCoverageOptions
205 getSancovOptsFromCGOpts(const CodeGenOptions &CGOpts) {
206   SanitizerCoverageOptions Opts;
207   Opts.CoverageType =
208       static_cast<SanitizerCoverageOptions::Type>(CGOpts.SanitizeCoverageType);
209   Opts.IndirectCalls = CGOpts.SanitizeCoverageIndirectCalls;
210   Opts.TraceBB = CGOpts.SanitizeCoverageTraceBB;
211   Opts.TraceCmp = CGOpts.SanitizeCoverageTraceCmp;
212   Opts.TraceDiv = CGOpts.SanitizeCoverageTraceDiv;
213   Opts.TraceGep = CGOpts.SanitizeCoverageTraceGep;
214   Opts.Use8bitCounters = CGOpts.SanitizeCoverage8bitCounters;
215   Opts.TracePC = CGOpts.SanitizeCoverageTracePC;
216   Opts.TracePCGuard = CGOpts.SanitizeCoverageTracePCGuard;
217   Opts.NoPrune = CGOpts.SanitizeCoverageNoPrune;
218   Opts.Inline8bitCounters = CGOpts.SanitizeCoverageInline8bitCounters;
219   Opts.PCTable = CGOpts.SanitizeCoveragePCTable;
220   Opts.StackDepth = CGOpts.SanitizeCoverageStackDepth;
221   return Opts;
222 }
223 
224 static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
225                                      legacy::PassManagerBase &PM) {
226   const PassManagerBuilderWrapper &BuilderWrapper =
227       static_cast<const PassManagerBuilderWrapper &>(Builder);
228   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
229   auto Opts = getSancovOptsFromCGOpts(CGOpts);
230   PM.add(createModuleSanitizerCoverageLegacyPassPass(Opts));
231 }
232 
233 // Check if ASan should use GC-friendly instrumentation for globals.
234 // First of all, there is no point if -fdata-sections is off (expect for MachO,
235 // where this is not a factor). Also, on ELF this feature requires an assembler
236 // extension that only works with -integrated-as at the moment.
237 static bool asanUseGlobalsGC(const Triple &T, const CodeGenOptions &CGOpts) {
238   if (!CGOpts.SanitizeAddressGlobalsDeadStripping)
239     return false;
240   switch (T.getObjectFormat()) {
241   case Triple::MachO:
242   case Triple::COFF:
243     return true;
244   case Triple::ELF:
245     return CGOpts.DataSections && !CGOpts.DisableIntegratedAS;
246   case Triple::XCOFF:
247     llvm::report_fatal_error("ASan not implemented for XCOFF.");
248   case Triple::Wasm:
249   case Triple::UnknownObjectFormat:
250     break;
251   }
252   return false;
253 }
254 
255 static void addAddressSanitizerPasses(const PassManagerBuilder &Builder,
256                                       legacy::PassManagerBase &PM) {
257   const PassManagerBuilderWrapper &BuilderWrapper =
258       static_cast<const PassManagerBuilderWrapper&>(Builder);
259   const Triple &T = BuilderWrapper.getTargetTriple();
260   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
261   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Address);
262   bool UseAfterScope = CGOpts.SanitizeAddressUseAfterScope;
263   bool UseOdrIndicator = CGOpts.SanitizeAddressUseOdrIndicator;
264   bool UseGlobalsGC = asanUseGlobalsGC(T, CGOpts);
265   PM.add(createAddressSanitizerFunctionPass(/*CompileKernel*/ false, Recover,
266                                             UseAfterScope));
267   PM.add(createModuleAddressSanitizerLegacyPassPass(
268       /*CompileKernel*/ false, Recover, UseGlobalsGC, UseOdrIndicator));
269 }
270 
271 static void addKernelAddressSanitizerPasses(const PassManagerBuilder &Builder,
272                                             legacy::PassManagerBase &PM) {
273   PM.add(createAddressSanitizerFunctionPass(
274       /*CompileKernel*/ true, /*Recover*/ true, /*UseAfterScope*/ false));
275   PM.add(createModuleAddressSanitizerLegacyPassPass(
276       /*CompileKernel*/ true, /*Recover*/ true, /*UseGlobalsGC*/ true,
277       /*UseOdrIndicator*/ false));
278 }
279 
280 static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
281                                             legacy::PassManagerBase &PM) {
282   const PassManagerBuilderWrapper &BuilderWrapper =
283       static_cast<const PassManagerBuilderWrapper &>(Builder);
284   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
285   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
286   PM.add(
287       createHWAddressSanitizerLegacyPassPass(/*CompileKernel*/ false, Recover));
288 }
289 
290 static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
291                                             legacy::PassManagerBase &PM) {
292   PM.add(createHWAddressSanitizerLegacyPassPass(
293       /*CompileKernel*/ true, /*Recover*/ true));
294 }
295 
296 static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
297                                              legacy::PassManagerBase &PM,
298                                              bool CompileKernel) {
299   const PassManagerBuilderWrapper &BuilderWrapper =
300       static_cast<const PassManagerBuilderWrapper&>(Builder);
301   const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
302   int TrackOrigins = CGOpts.SanitizeMemoryTrackOrigins;
303   bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::Memory);
304   PM.add(createMemorySanitizerLegacyPassPass(
305       MemorySanitizerOptions{TrackOrigins, Recover, CompileKernel}));
306 
307   // MemorySanitizer inserts complex instrumentation that mostly follows
308   // the logic of the original code, but operates on "shadow" values.
309   // It can benefit from re-running some general purpose optimization passes.
310   if (Builder.OptLevel > 0) {
311     PM.add(createEarlyCSEPass());
312     PM.add(createReassociatePass());
313     PM.add(createLICMPass());
314     PM.add(createGVNPass());
315     PM.add(createInstructionCombiningPass());
316     PM.add(createDeadStoreEliminationPass());
317   }
318 }
319 
320 static void addMemorySanitizerPass(const PassManagerBuilder &Builder,
321                                    legacy::PassManagerBase &PM) {
322   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ false);
323 }
324 
325 static void addKernelMemorySanitizerPass(const PassManagerBuilder &Builder,
326                                          legacy::PassManagerBase &PM) {
327   addGeneralOptsForMemorySanitizer(Builder, PM, /*CompileKernel*/ true);
328 }
329 
330 static void addThreadSanitizerPass(const PassManagerBuilder &Builder,
331                                    legacy::PassManagerBase &PM) {
332   PM.add(createThreadSanitizerLegacyPassPass());
333 }
334 
335 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
336                                      legacy::PassManagerBase &PM) {
337   const PassManagerBuilderWrapper &BuilderWrapper =
338       static_cast<const PassManagerBuilderWrapper&>(Builder);
339   const LangOptions &LangOpts = BuilderWrapper.getLangOpts();
340   PM.add(createDataFlowSanitizerPass(LangOpts.SanitizerBlacklistFiles));
341 }
342 
343 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
344                                          const CodeGenOptions &CodeGenOpts) {
345   TargetLibraryInfoImpl *TLII = new TargetLibraryInfoImpl(TargetTriple);
346 
347   switch (CodeGenOpts.getVecLib()) {
348   case CodeGenOptions::Accelerate:
349     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::Accelerate);
350     break;
351   case CodeGenOptions::MASSV:
352     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::MASSV);
353     break;
354   case CodeGenOptions::SVML:
355     TLII->addVectorizableFunctionsFromVecLib(TargetLibraryInfoImpl::SVML);
356     break;
357   default:
358     break;
359   }
360   return TLII;
361 }
362 
363 static void addSymbolRewriterPass(const CodeGenOptions &Opts,
364                                   legacy::PassManager *MPM) {
365   llvm::SymbolRewriter::RewriteDescriptorList DL;
366 
367   llvm::SymbolRewriter::RewriteMapParser MapParser;
368   for (const auto &MapFile : Opts.RewriteMapFiles)
369     MapParser.parse(MapFile, &DL);
370 
371   MPM->add(createRewriteSymbolsPass(DL));
372 }
373 
374 static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
375   switch (CodeGenOpts.OptimizationLevel) {
376   default:
377     llvm_unreachable("Invalid optimization level!");
378   case 0:
379     return CodeGenOpt::None;
380   case 1:
381     return CodeGenOpt::Less;
382   case 2:
383     return CodeGenOpt::Default; // O2/Os/Oz
384   case 3:
385     return CodeGenOpt::Aggressive;
386   }
387 }
388 
389 static Optional<llvm::CodeModel::Model>
390 getCodeModel(const CodeGenOptions &CodeGenOpts) {
391   unsigned CodeModel = llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
392                            .Case("tiny", llvm::CodeModel::Tiny)
393                            .Case("small", llvm::CodeModel::Small)
394                            .Case("kernel", llvm::CodeModel::Kernel)
395                            .Case("medium", llvm::CodeModel::Medium)
396                            .Case("large", llvm::CodeModel::Large)
397                            .Case("default", ~1u)
398                            .Default(~0u);
399   assert(CodeModel != ~0u && "invalid code model!");
400   if (CodeModel == ~1u)
401     return None;
402   return static_cast<llvm::CodeModel::Model>(CodeModel);
403 }
404 
405 static CodeGenFileType getCodeGenFileType(BackendAction Action) {
406   if (Action == Backend_EmitObj)
407     return CGFT_ObjectFile;
408   else if (Action == Backend_EmitMCNull)
409     return CGFT_Null;
410   else {
411     assert(Action == Backend_EmitAssembly && "Invalid action!");
412     return CGFT_AssemblyFile;
413   }
414 }
415 
416 static void initTargetOptions(llvm::TargetOptions &Options,
417                               const CodeGenOptions &CodeGenOpts,
418                               const clang::TargetOptions &TargetOpts,
419                               const LangOptions &LangOpts,
420                               const HeaderSearchOptions &HSOpts) {
421   Options.ThreadModel =
422       llvm::StringSwitch<llvm::ThreadModel::Model>(CodeGenOpts.ThreadModel)
423           .Case("posix", llvm::ThreadModel::POSIX)
424           .Case("single", llvm::ThreadModel::Single);
425 
426   // Set float ABI type.
427   assert((CodeGenOpts.FloatABI == "soft" || CodeGenOpts.FloatABI == "softfp" ||
428           CodeGenOpts.FloatABI == "hard" || CodeGenOpts.FloatABI.empty()) &&
429          "Invalid Floating Point ABI!");
430   Options.FloatABIType =
431       llvm::StringSwitch<llvm::FloatABI::ABIType>(CodeGenOpts.FloatABI)
432           .Case("soft", llvm::FloatABI::Soft)
433           .Case("softfp", llvm::FloatABI::Soft)
434           .Case("hard", llvm::FloatABI::Hard)
435           .Default(llvm::FloatABI::Default);
436 
437   // Set FP fusion mode.
438   switch (LangOpts.getDefaultFPContractMode()) {
439   case LangOptions::FPC_Off:
440     // Preserve any contraction performed by the front-end.  (Strict performs
441     // splitting of the muladd intrinsic in the backend.)
442     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
443     break;
444   case LangOptions::FPC_On:
445     Options.AllowFPOpFusion = llvm::FPOpFusion::Standard;
446     break;
447   case LangOptions::FPC_Fast:
448     Options.AllowFPOpFusion = llvm::FPOpFusion::Fast;
449     break;
450   }
451 
452   Options.UseInitArray = CodeGenOpts.UseInitArray;
453   Options.DisableIntegratedAS = CodeGenOpts.DisableIntegratedAS;
454   Options.CompressDebugSections = CodeGenOpts.getCompressDebugSections();
455   Options.RelaxELFRelocations = CodeGenOpts.RelaxELFRelocations;
456 
457   // Set EABI version.
458   Options.EABIVersion = TargetOpts.EABIVersion;
459 
460   if (LangOpts.SjLjExceptions)
461     Options.ExceptionModel = llvm::ExceptionHandling::SjLj;
462   if (LangOpts.SEHExceptions)
463     Options.ExceptionModel = llvm::ExceptionHandling::WinEH;
464   if (LangOpts.DWARFExceptions)
465     Options.ExceptionModel = llvm::ExceptionHandling::DwarfCFI;
466   if (LangOpts.WasmExceptions)
467     Options.ExceptionModel = llvm::ExceptionHandling::Wasm;
468 
469   Options.NoInfsFPMath = CodeGenOpts.NoInfsFPMath;
470   Options.NoNaNsFPMath = CodeGenOpts.NoNaNsFPMath;
471   Options.NoZerosInBSS = CodeGenOpts.NoZeroInitializedInBSS;
472   Options.UnsafeFPMath = CodeGenOpts.UnsafeFPMath;
473   Options.StackAlignmentOverride = CodeGenOpts.StackAlignment;
474   Options.FunctionSections = CodeGenOpts.FunctionSections;
475   Options.DataSections = CodeGenOpts.DataSections;
476   Options.UniqueSectionNames = CodeGenOpts.UniqueSectionNames;
477   Options.TLSSize = CodeGenOpts.TLSSize;
478   Options.EmulatedTLS = CodeGenOpts.EmulatedTLS;
479   Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
480   Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
481   Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
482   Options.EmitAddrsig = CodeGenOpts.Addrsig;
483   Options.EnableDebugEntryValues = CodeGenOpts.EnableDebugEntryValues;
484   Options.ForceDwarfFrameSection = CodeGenOpts.ForceDwarfFrameSection;
485 
486   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
487   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
488   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;
489   Options.MCOptions.MCUseDwarfDirectory = !CodeGenOpts.NoDwarfDirectoryAsm;
490   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
491   Options.MCOptions.MCIncrementalLinkerCompatible =
492       CodeGenOpts.IncrementalLinkerCompatible;
493   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
494   Options.MCOptions.MCNoWarn = CodeGenOpts.NoWarn;
495   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
496   Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
497   Options.MCOptions.ABIName = TargetOpts.ABI;
498   for (const auto &Entry : HSOpts.UserEntries)
499     if (!Entry.IsFramework &&
500         (Entry.Group == frontend::IncludeDirGroup::Quoted ||
501          Entry.Group == frontend::IncludeDirGroup::Angled ||
502          Entry.Group == frontend::IncludeDirGroup::System))
503       Options.MCOptions.IASSearchPaths.push_back(
504           Entry.IgnoreSysRoot ? Entry.Path : HSOpts.Sysroot + Entry.Path);
505 }
506 static Optional<GCOVOptions> getGCOVOptions(const CodeGenOptions &CodeGenOpts) {
507   if (CodeGenOpts.DisableGCov)
508     return None;
509   if (!CodeGenOpts.EmitGcovArcs && !CodeGenOpts.EmitGcovNotes)
510     return None;
511   // Not using 'GCOVOptions::getDefault' allows us to avoid exiting if
512   // LLVM's -default-gcov-version flag is set to something invalid.
513   GCOVOptions Options;
514   Options.EmitNotes = CodeGenOpts.EmitGcovNotes;
515   Options.EmitData = CodeGenOpts.EmitGcovArcs;
516   llvm::copy(CodeGenOpts.CoverageVersion, std::begin(Options.Version));
517   Options.UseCfgChecksum = CodeGenOpts.CoverageExtraChecksum;
518   Options.NoRedZone = CodeGenOpts.DisableRedZone;
519   Options.FunctionNamesInData = !CodeGenOpts.CoverageNoFunctionNamesInData;
520   Options.Filter = CodeGenOpts.ProfileFilterFiles;
521   Options.Exclude = CodeGenOpts.ProfileExcludeFiles;
522   Options.ExitBlockBeforeBody = CodeGenOpts.CoverageExitBlockBeforeBody;
523   return Options;
524 }
525 
526 static Optional<InstrProfOptions>
527 getInstrProfOptions(const CodeGenOptions &CodeGenOpts,
528                     const LangOptions &LangOpts) {
529   if (!CodeGenOpts.hasProfileClangInstr())
530     return None;
531   InstrProfOptions Options;
532   Options.NoRedZone = CodeGenOpts.DisableRedZone;
533   Options.InstrProfileOutput = CodeGenOpts.InstrProfileOutput;
534 
535   // TODO: Surface the option to emit atomic profile counter increments at
536   // the driver level.
537   Options.Atomic = LangOpts.Sanitize.has(SanitizerKind::Thread);
538   return Options;
539 }
540 
541 void EmitAssemblyHelper::CreatePasses(legacy::PassManager &MPM,
542                                       legacy::FunctionPassManager &FPM) {
543   // Handle disabling of all LLVM passes, where we want to preserve the
544   // internal module before any optimization.
545   if (CodeGenOpts.DisableLLVMPasses)
546     return;
547 
548   // Figure out TargetLibraryInfo.  This needs to be added to MPM and FPM
549   // manually (and not via PMBuilder), since some passes (eg. InstrProfiling)
550   // are inserted before PMBuilder ones - they'd get the default-constructed
551   // TLI with an unknown target otherwise.
552   Triple TargetTriple(TheModule->getTargetTriple());
553   std::unique_ptr<TargetLibraryInfoImpl> TLII(
554       createTLII(TargetTriple, CodeGenOpts));
555 
556   PassManagerBuilderWrapper PMBuilder(TargetTriple, CodeGenOpts, LangOpts);
557 
558   // At O0 and O1 we only run the always inliner which is more efficient. At
559   // higher optimization levels we run the normal inliner.
560   if (CodeGenOpts.OptimizationLevel <= 1) {
561     bool InsertLifetimeIntrinsics = (CodeGenOpts.OptimizationLevel != 0 &&
562                                      !CodeGenOpts.DisableLifetimeMarkers);
563     PMBuilder.Inliner = createAlwaysInlinerLegacyPass(InsertLifetimeIntrinsics);
564   } else {
565     // We do not want to inline hot callsites for SamplePGO module-summary build
566     // because profile annotation will happen again in ThinLTO backend, and we
567     // want the IR of the hot path to match the profile.
568     PMBuilder.Inliner = createFunctionInliningPass(
569         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
570         (!CodeGenOpts.SampleProfileFile.empty() &&
571          CodeGenOpts.PrepareForThinLTO));
572   }
573 
574   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
575   PMBuilder.SizeLevel = CodeGenOpts.OptimizeSize;
576   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
577   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
578 
579   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
580   // Loop interleaving in the loop vectorizer has historically been set to be
581   // enabled when loop unrolling is enabled.
582   PMBuilder.LoopsInterleaved = CodeGenOpts.UnrollLoops;
583   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
584   PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
585   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
586   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
587 
588   MPM.add(new TargetLibraryInfoWrapperPass(*TLII));
589 
590   if (TM)
591     TM->adjustPassManager(PMBuilder);
592 
593   if (CodeGenOpts.DebugInfoForProfiling ||
594       !CodeGenOpts.SampleProfileFile.empty())
595     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
596                            addAddDiscriminatorsPass);
597 
598   // In ObjC ARC mode, add the main ARC optimization passes.
599   if (LangOpts.ObjCAutoRefCount) {
600     PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
601                            addObjCARCExpandPass);
602     PMBuilder.addExtension(PassManagerBuilder::EP_ModuleOptimizerEarly,
603                            addObjCARCAPElimPass);
604     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
605                            addObjCARCOptPass);
606   }
607 
608   if (LangOpts.Coroutines)
609     addCoroutinePassesToExtensionPoints(PMBuilder);
610 
611   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
612     PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
613                            addBoundsCheckingPass);
614     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
615                            addBoundsCheckingPass);
616   }
617 
618   if (CodeGenOpts.SanitizeCoverageType ||
619       CodeGenOpts.SanitizeCoverageIndirectCalls ||
620       CodeGenOpts.SanitizeCoverageTraceCmp) {
621     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
622                            addSanitizerCoveragePass);
623     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
624                            addSanitizerCoveragePass);
625   }
626 
627   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
628     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
629                            addAddressSanitizerPasses);
630     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
631                            addAddressSanitizerPasses);
632   }
633 
634   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
635     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
636                            addKernelAddressSanitizerPasses);
637     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
638                            addKernelAddressSanitizerPasses);
639   }
640 
641   if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
642     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
643                            addHWAddressSanitizerPasses);
644     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
645                            addHWAddressSanitizerPasses);
646   }
647 
648   if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
649     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
650                            addKernelHWAddressSanitizerPasses);
651     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
652                            addKernelHWAddressSanitizerPasses);
653   }
654 
655   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
656     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
657                            addMemorySanitizerPass);
658     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
659                            addMemorySanitizerPass);
660   }
661 
662   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
663     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
664                            addKernelMemorySanitizerPass);
665     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
666                            addKernelMemorySanitizerPass);
667   }
668 
669   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
670     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
671                            addThreadSanitizerPass);
672     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
673                            addThreadSanitizerPass);
674   }
675 
676   if (LangOpts.Sanitize.has(SanitizerKind::DataFlow)) {
677     PMBuilder.addExtension(PassManagerBuilder::EP_OptimizerLast,
678                            addDataFlowSanitizerPass);
679     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
680                            addDataFlowSanitizerPass);
681   }
682 
683   // Set up the per-function pass manager.
684   FPM.add(new TargetLibraryInfoWrapperPass(*TLII));
685   if (CodeGenOpts.VerifyModule)
686     FPM.add(createVerifierPass());
687 
688   // Set up the per-module pass manager.
689   if (!CodeGenOpts.RewriteMapFiles.empty())
690     addSymbolRewriterPass(CodeGenOpts, &MPM);
691 
692   if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts)) {
693     MPM.add(createGCOVProfilerPass(*Options));
694     if (CodeGenOpts.getDebugInfo() == codegenoptions::NoDebugInfo)
695       MPM.add(createStripSymbolsPass(true));
696   }
697 
698   if (Optional<InstrProfOptions> Options =
699           getInstrProfOptions(CodeGenOpts, LangOpts))
700     MPM.add(createInstrProfilingLegacyPass(*Options, false));
701 
702   bool hasIRInstr = false;
703   if (CodeGenOpts.hasProfileIRInstr()) {
704     PMBuilder.EnablePGOInstrGen = true;
705     hasIRInstr = true;
706   }
707   if (CodeGenOpts.hasProfileCSIRInstr()) {
708     assert(!CodeGenOpts.hasProfileCSIRUse() &&
709            "Cannot have both CSProfileUse pass and CSProfileGen pass at the "
710            "same time");
711     assert(!hasIRInstr &&
712            "Cannot have both ProfileGen pass and CSProfileGen pass at the "
713            "same time");
714     PMBuilder.EnablePGOCSInstrGen = true;
715     hasIRInstr = true;
716   }
717   if (hasIRInstr) {
718     if (!CodeGenOpts.InstrProfileOutput.empty())
719       PMBuilder.PGOInstrGen = CodeGenOpts.InstrProfileOutput;
720     else
721       PMBuilder.PGOInstrGen = DefaultProfileGenName;
722   }
723   if (CodeGenOpts.hasProfileIRUse()) {
724     PMBuilder.PGOInstrUse = CodeGenOpts.ProfileInstrumentUsePath;
725     PMBuilder.EnablePGOCSInstrUse = CodeGenOpts.hasProfileCSIRUse();
726   }
727 
728   if (!CodeGenOpts.SampleProfileFile.empty())
729     PMBuilder.PGOSampleUse = CodeGenOpts.SampleProfileFile;
730 
731   PMBuilder.populateFunctionPassManager(FPM);
732   PMBuilder.populateModulePassManager(MPM);
733 }
734 
735 static void setCommandLineOpts(const CodeGenOptions &CodeGenOpts) {
736   SmallVector<const char *, 16> BackendArgs;
737   BackendArgs.push_back("clang"); // Fake program name.
738   if (!CodeGenOpts.DebugPass.empty()) {
739     BackendArgs.push_back("-debug-pass");
740     BackendArgs.push_back(CodeGenOpts.DebugPass.c_str());
741   }
742   if (!CodeGenOpts.LimitFloatPrecision.empty()) {
743     BackendArgs.push_back("-limit-float-precision");
744     BackendArgs.push_back(CodeGenOpts.LimitFloatPrecision.c_str());
745   }
746   BackendArgs.push_back(nullptr);
747   llvm::cl::ParseCommandLineOptions(BackendArgs.size() - 1,
748                                     BackendArgs.data());
749 }
750 
751 void EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
752   // Create the TargetMachine for generating code.
753   std::string Error;
754   std::string Triple = TheModule->getTargetTriple();
755   const llvm::Target *TheTarget = TargetRegistry::lookupTarget(Triple, Error);
756   if (!TheTarget) {
757     if (MustCreateTM)
758       Diags.Report(diag::err_fe_unable_to_create_target) << Error;
759     return;
760   }
761 
762   Optional<llvm::CodeModel::Model> CM = getCodeModel(CodeGenOpts);
763   std::string FeaturesStr =
764       llvm::join(TargetOpts.Features.begin(), TargetOpts.Features.end(), ",");
765   llvm::Reloc::Model RM = CodeGenOpts.RelocationModel;
766   CodeGenOpt::Level OptLevel = getCGOptLevel(CodeGenOpts);
767 
768   llvm::TargetOptions Options;
769   initTargetOptions(Options, CodeGenOpts, TargetOpts, LangOpts, HSOpts);
770   TM.reset(TheTarget->createTargetMachine(Triple, TargetOpts.CPU, FeaturesStr,
771                                           Options, RM, CM, OptLevel));
772 }
773 
774 bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
775                                        BackendAction Action,
776                                        raw_pwrite_stream &OS,
777                                        raw_pwrite_stream *DwoOS) {
778   // Add LibraryInfo.
779   llvm::Triple TargetTriple(TheModule->getTargetTriple());
780   std::unique_ptr<TargetLibraryInfoImpl> TLII(
781       createTLII(TargetTriple, CodeGenOpts));
782   CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
783 
784   // Normal mode, emit a .s or .o file by running the code generator. Note,
785   // this also adds codegenerator level optimization passes.
786   CodeGenFileType CGFT = getCodeGenFileType(Action);
787 
788   // Add ObjC ARC final-cleanup optimizations. This is done as part of the
789   // "codegen" passes so that it isn't run multiple times when there is
790   // inlining happening.
791   if (CodeGenOpts.OptimizationLevel > 0)
792     CodeGenPasses.add(createObjCARCContractPass());
793 
794   if (TM->addPassesToEmitFile(CodeGenPasses, OS, DwoOS, CGFT,
795                               /*DisableVerify=*/!CodeGenOpts.VerifyModule)) {
796     Diags.Report(diag::err_fe_unable_to_interface_with_target);
797     return false;
798   }
799 
800   return true;
801 }
802 
803 void EmitAssemblyHelper::EmitAssembly(BackendAction Action,
804                                       std::unique_ptr<raw_pwrite_stream> OS) {
805   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
806 
807   setCommandLineOpts(CodeGenOpts);
808 
809   bool UsesCodeGen = (Action != Backend_EmitNothing &&
810                       Action != Backend_EmitBC &&
811                       Action != Backend_EmitLL);
812   CreateTargetMachine(UsesCodeGen);
813 
814   if (UsesCodeGen && !TM)
815     return;
816   if (TM)
817     TheModule->setDataLayout(TM->createDataLayout());
818 
819   legacy::PassManager PerModulePasses;
820   PerModulePasses.add(
821       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
822 
823   legacy::FunctionPassManager PerFunctionPasses(TheModule);
824   PerFunctionPasses.add(
825       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
826 
827   CreatePasses(PerModulePasses, PerFunctionPasses);
828 
829   legacy::PassManager CodeGenPasses;
830   CodeGenPasses.add(
831       createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
832 
833   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
834 
835   switch (Action) {
836   case Backend_EmitNothing:
837     break;
838 
839   case Backend_EmitBC:
840     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
841       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
842         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
843         if (!ThinLinkOS)
844           return;
845       }
846       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
847                                CodeGenOpts.EnableSplitLTOUnit);
848       PerModulePasses.add(createWriteThinLTOBitcodePass(
849           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
850     } else {
851       // Emit a module summary by default for Regular LTO except for ld64
852       // targets
853       bool EmitLTOSummary =
854           (CodeGenOpts.PrepareForLTO &&
855            !CodeGenOpts.DisableLLVMPasses &&
856            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
857                llvm::Triple::Apple);
858       if (EmitLTOSummary) {
859         if (!TheModule->getModuleFlag("ThinLTO"))
860           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
861         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
862                                  uint32_t(1));
863       }
864 
865       PerModulePasses.add(createBitcodeWriterPass(
866           *OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
867     }
868     break;
869 
870   case Backend_EmitLL:
871     PerModulePasses.add(
872         createPrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
873     break;
874 
875   default:
876     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
877       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
878       if (!DwoOS)
879         return;
880     }
881     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
882                        DwoOS ? &DwoOS->os() : nullptr))
883       return;
884   }
885 
886   // Before executing passes, print the final values of the LLVM options.
887   cl::PrintOptionValues();
888 
889   // Run passes. For now we do all passes at once, but eventually we
890   // would like to have the option of streaming code generation.
891 
892   {
893     PrettyStackTraceString CrashInfo("Per-function optimization");
894     llvm::TimeTraceScope TimeScope("PerFunctionPasses");
895 
896     PerFunctionPasses.doInitialization();
897     for (Function &F : *TheModule)
898       if (!F.isDeclaration())
899         PerFunctionPasses.run(F);
900     PerFunctionPasses.doFinalization();
901   }
902 
903   {
904     PrettyStackTraceString CrashInfo("Per-module optimization passes");
905     llvm::TimeTraceScope TimeScope("PerModulePasses");
906     PerModulePasses.run(*TheModule);
907   }
908 
909   {
910     PrettyStackTraceString CrashInfo("Code generation");
911     llvm::TimeTraceScope TimeScope("CodeGenPasses");
912     CodeGenPasses.run(*TheModule);
913   }
914 
915   if (ThinLinkOS)
916     ThinLinkOS->keep();
917   if (DwoOS)
918     DwoOS->keep();
919 }
920 
921 static PassBuilder::OptimizationLevel mapToLevel(const CodeGenOptions &Opts) {
922   switch (Opts.OptimizationLevel) {
923   default:
924     llvm_unreachable("Invalid optimization level!");
925 
926   case 1:
927     return PassBuilder::O1;
928 
929   case 2:
930     switch (Opts.OptimizeSize) {
931     default:
932       llvm_unreachable("Invalid optimization level for size!");
933 
934     case 0:
935       return PassBuilder::O2;
936 
937     case 1:
938       return PassBuilder::Os;
939 
940     case 2:
941       return PassBuilder::Oz;
942     }
943 
944   case 3:
945     return PassBuilder::O3;
946   }
947 }
948 
949 static void addSanitizersAtO0(ModulePassManager &MPM,
950                               const Triple &TargetTriple,
951                               const LangOptions &LangOpts,
952                               const CodeGenOptions &CodeGenOpts) {
953   auto ASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
954     MPM.addPass(RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
955     bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
956     MPM.addPass(createModuleToFunctionPassAdaptor(AddressSanitizerPass(
957         CompileKernel, Recover, CodeGenOpts.SanitizeAddressUseAfterScope)));
958     bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
959     MPM.addPass(
960         ModuleAddressSanitizerPass(CompileKernel, Recover, ModuleUseAfterScope,
961                                    CodeGenOpts.SanitizeAddressUseOdrIndicator));
962   };
963 
964   if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
965     ASanPass(SanitizerKind::Address, /*CompileKernel=*/false);
966   }
967 
968   if (LangOpts.Sanitize.has(SanitizerKind::KernelAddress)) {
969     ASanPass(SanitizerKind::KernelAddress, /*CompileKernel=*/true);
970   }
971 
972   if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
973     MPM.addPass(MemorySanitizerPass({}));
974     MPM.addPass(createModuleToFunctionPassAdaptor(MemorySanitizerPass({})));
975   }
976 
977   if (LangOpts.Sanitize.has(SanitizerKind::KernelMemory)) {
978     MPM.addPass(createModuleToFunctionPassAdaptor(
979         MemorySanitizerPass({0, false, /*Kernel=*/true})));
980   }
981 
982   if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
983     MPM.addPass(ThreadSanitizerPass());
984     MPM.addPass(createModuleToFunctionPassAdaptor(ThreadSanitizerPass()));
985   }
986 }
987 
988 /// A clean version of `EmitAssembly` that uses the new pass manager.
989 ///
990 /// Not all features are currently supported in this system, but where
991 /// necessary it falls back to the legacy pass manager to at least provide
992 /// basic functionality.
993 ///
994 /// This API is planned to have its functionality finished and then to replace
995 /// `EmitAssembly` at some point in the future when the default switches.
996 void EmitAssemblyHelper::EmitAssemblyWithNewPassManager(
997     BackendAction Action, std::unique_ptr<raw_pwrite_stream> OS) {
998   TimeRegion Region(FrontendTimesIsEnabled ? &CodeGenerationTime : nullptr);
999   setCommandLineOpts(CodeGenOpts);
1000 
1001   bool RequiresCodeGen = (Action != Backend_EmitNothing &&
1002                           Action != Backend_EmitBC &&
1003                           Action != Backend_EmitLL);
1004   CreateTargetMachine(RequiresCodeGen);
1005 
1006   if (RequiresCodeGen && !TM)
1007     return;
1008   if (TM)
1009     TheModule->setDataLayout(TM->createDataLayout());
1010 
1011   Optional<PGOOptions> PGOOpt;
1012 
1013   if (CodeGenOpts.hasProfileIRInstr())
1014     // -fprofile-generate.
1015     PGOOpt = PGOOptions(CodeGenOpts.InstrProfileOutput.empty()
1016                             ? DefaultProfileGenName
1017                             : CodeGenOpts.InstrProfileOutput,
1018                         "", "", PGOOptions::IRInstr, PGOOptions::NoCSAction,
1019                         CodeGenOpts.DebugInfoForProfiling);
1020   else if (CodeGenOpts.hasProfileIRUse()) {
1021     // -fprofile-use.
1022     auto CSAction = CodeGenOpts.hasProfileCSIRUse() ? PGOOptions::CSIRUse
1023                                                     : PGOOptions::NoCSAction;
1024     PGOOpt = PGOOptions(CodeGenOpts.ProfileInstrumentUsePath, "",
1025                         CodeGenOpts.ProfileRemappingFile, PGOOptions::IRUse,
1026                         CSAction, CodeGenOpts.DebugInfoForProfiling);
1027   } else if (!CodeGenOpts.SampleProfileFile.empty())
1028     // -fprofile-sample-use
1029     PGOOpt =
1030         PGOOptions(CodeGenOpts.SampleProfileFile, "",
1031                    CodeGenOpts.ProfileRemappingFile, PGOOptions::SampleUse,
1032                    PGOOptions::NoCSAction, CodeGenOpts.DebugInfoForProfiling);
1033   else if (CodeGenOpts.DebugInfoForProfiling)
1034     // -fdebug-info-for-profiling
1035     PGOOpt = PGOOptions("", "", "", PGOOptions::NoAction,
1036                         PGOOptions::NoCSAction, true);
1037 
1038   // Check to see if we want to generate a CS profile.
1039   if (CodeGenOpts.hasProfileCSIRInstr()) {
1040     assert(!CodeGenOpts.hasProfileCSIRUse() &&
1041            "Cannot have both CSProfileUse pass and CSProfileGen pass at "
1042            "the same time");
1043     if (PGOOpt.hasValue()) {
1044       assert(PGOOpt->Action != PGOOptions::IRInstr &&
1045              PGOOpt->Action != PGOOptions::SampleUse &&
1046              "Cannot run CSProfileGen pass with ProfileGen or SampleUse "
1047              " pass");
1048       PGOOpt->CSProfileGenFile = CodeGenOpts.InstrProfileOutput.empty()
1049                                      ? DefaultProfileGenName
1050                                      : CodeGenOpts.InstrProfileOutput;
1051       PGOOpt->CSAction = PGOOptions::CSIRInstr;
1052     } else
1053       PGOOpt = PGOOptions("",
1054                           CodeGenOpts.InstrProfileOutput.empty()
1055                               ? DefaultProfileGenName
1056                               : CodeGenOpts.InstrProfileOutput,
1057                           "", PGOOptions::NoAction, PGOOptions::CSIRInstr,
1058                           CodeGenOpts.DebugInfoForProfiling);
1059   }
1060 
1061   PipelineTuningOptions PTO;
1062   PTO.LoopUnrolling = CodeGenOpts.UnrollLoops;
1063   // For historical reasons, loop interleaving is set to mirror setting for loop
1064   // unrolling.
1065   PTO.LoopInterleaving = CodeGenOpts.UnrollLoops;
1066   PTO.LoopVectorization = CodeGenOpts.VectorizeLoop;
1067   PTO.SLPVectorization = CodeGenOpts.VectorizeSLP;
1068 
1069   PassInstrumentationCallbacks PIC;
1070   StandardInstrumentations SI;
1071   SI.registerCallbacks(PIC);
1072   PassBuilder PB(TM.get(), PTO, PGOOpt, &PIC);
1073 
1074   // Attempt to load pass plugins and register their callbacks with PB.
1075   for (auto &PluginFN : CodeGenOpts.PassPlugins) {
1076     auto PassPlugin = PassPlugin::Load(PluginFN);
1077     if (PassPlugin) {
1078       PassPlugin->registerPassBuilderCallbacks(PB);
1079     } else {
1080       Diags.Report(diag::err_fe_unable_to_load_plugin)
1081           << PluginFN << toString(PassPlugin.takeError());
1082     }
1083   }
1084 #define HANDLE_EXTENSION(Ext)                                                  \
1085   get##Ext##PluginInfo().RegisterPassBuilderCallbacks(PB);
1086 #include "llvm/Support/Extension.def"
1087 
1088   LoopAnalysisManager LAM(CodeGenOpts.DebugPassManager);
1089   FunctionAnalysisManager FAM(CodeGenOpts.DebugPassManager);
1090   CGSCCAnalysisManager CGAM(CodeGenOpts.DebugPassManager);
1091   ModuleAnalysisManager MAM(CodeGenOpts.DebugPassManager);
1092 
1093   // Register the AA manager first so that our version is the one used.
1094   FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
1095 
1096   // Register the target library analysis directly and give it a customized
1097   // preset TLI.
1098   Triple TargetTriple(TheModule->getTargetTriple());
1099   std::unique_ptr<TargetLibraryInfoImpl> TLII(
1100       createTLII(TargetTriple, CodeGenOpts));
1101   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
1102 
1103   // Register all the basic analyses with the managers.
1104   PB.registerModuleAnalyses(MAM);
1105   PB.registerCGSCCAnalyses(CGAM);
1106   PB.registerFunctionAnalyses(FAM);
1107   PB.registerLoopAnalyses(LAM);
1108   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
1109 
1110   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
1111 
1112   if (!CodeGenOpts.DisableLLVMPasses) {
1113     bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
1114     bool IsLTO = CodeGenOpts.PrepareForLTO;
1115 
1116     if (CodeGenOpts.OptimizationLevel == 0) {
1117       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1118         MPM.addPass(GCOVProfilerPass(*Options));
1119       if (Optional<InstrProfOptions> Options =
1120               getInstrProfOptions(CodeGenOpts, LangOpts))
1121         MPM.addPass(InstrProfiling(*Options, false));
1122 
1123       // Build a minimal pipeline based on the semantics required by Clang,
1124       // which is just that always inlining occurs. Further, disable generating
1125       // lifetime intrinsics to avoid enabling further optimizations during
1126       // code generation.
1127       MPM.addPass(AlwaysInlinerPass(/*InsertLifetimeIntrinsics=*/false));
1128 
1129       // At -O0, we can still do PGO. Add all the requested passes for
1130       // instrumentation PGO, if requested.
1131       if (PGOOpt && (PGOOpt->Action == PGOOptions::IRInstr ||
1132                      PGOOpt->Action == PGOOptions::IRUse))
1133         PB.addPGOInstrPassesForO0(
1134             MPM, CodeGenOpts.DebugPassManager,
1135             /* RunProfileGen */ (PGOOpt->Action == PGOOptions::IRInstr),
1136             /* IsCS */ false, PGOOpt->ProfileFile,
1137             PGOOpt->ProfileRemappingFile);
1138 
1139       // At -O0 we directly run necessary sanitizer passes.
1140       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1141         MPM.addPass(createModuleToFunctionPassAdaptor(BoundsCheckingPass()));
1142 
1143       // Lastly, add semantically necessary passes for LTO.
1144       if (IsLTO || IsThinLTO) {
1145         MPM.addPass(CanonicalizeAliasesPass());
1146         MPM.addPass(NameAnonGlobalPass());
1147       }
1148     } else {
1149       // Map our optimization levels into one of the distinct levels used to
1150       // configure the pipeline.
1151       PassBuilder::OptimizationLevel Level = mapToLevel(CodeGenOpts);
1152 
1153       PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1154         MPM.addPass(createModuleToFunctionPassAdaptor(
1155             EntryExitInstrumenterPass(/*PostInlining=*/false)));
1156       });
1157 
1158       // Register callbacks to schedule sanitizer passes at the appropriate part of
1159       // the pipeline.
1160       // FIXME: either handle asan/the remaining sanitizers or error out
1161       if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds))
1162         PB.registerScalarOptimizerLateEPCallback(
1163             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1164               FPM.addPass(BoundsCheckingPass());
1165             });
1166       if (LangOpts.Sanitize.has(SanitizerKind::Memory)) {
1167         PB.registerPipelineStartEPCallback([](ModulePassManager &MPM) {
1168           MPM.addPass(MemorySanitizerPass({}));
1169         });
1170         PB.registerOptimizerLastEPCallback(
1171             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1172               FPM.addPass(MemorySanitizerPass({}));
1173             });
1174       }
1175       if (LangOpts.Sanitize.has(SanitizerKind::Thread)) {
1176         PB.registerPipelineStartEPCallback(
1177             [](ModulePassManager &MPM) { MPM.addPass(ThreadSanitizerPass()); });
1178         PB.registerOptimizerLastEPCallback(
1179             [](FunctionPassManager &FPM, PassBuilder::OptimizationLevel Level) {
1180               FPM.addPass(ThreadSanitizerPass());
1181             });
1182       }
1183       if (LangOpts.Sanitize.has(SanitizerKind::Address)) {
1184         PB.registerPipelineStartEPCallback([&](ModulePassManager &MPM) {
1185           MPM.addPass(
1186               RequireAnalysisPass<ASanGlobalsMetadataAnalysis, Module>());
1187         });
1188         bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::Address);
1189         bool UseAfterScope = CodeGenOpts.SanitizeAddressUseAfterScope;
1190         PB.registerOptimizerLastEPCallback(
1191             [Recover, UseAfterScope](FunctionPassManager &FPM,
1192                                      PassBuilder::OptimizationLevel Level) {
1193               FPM.addPass(AddressSanitizerPass(
1194                   /*CompileKernel=*/false, Recover, UseAfterScope));
1195             });
1196         bool ModuleUseAfterScope = asanUseGlobalsGC(TargetTriple, CodeGenOpts);
1197         bool UseOdrIndicator = CodeGenOpts.SanitizeAddressUseOdrIndicator;
1198         PB.registerPipelineStartEPCallback(
1199             [Recover, ModuleUseAfterScope,
1200              UseOdrIndicator](ModulePassManager &MPM) {
1201               MPM.addPass(ModuleAddressSanitizerPass(
1202                   /*CompileKernel=*/false, Recover, ModuleUseAfterScope,
1203                   UseOdrIndicator));
1204             });
1205       }
1206       if (Optional<GCOVOptions> Options = getGCOVOptions(CodeGenOpts))
1207         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1208           MPM.addPass(GCOVProfilerPass(*Options));
1209         });
1210       if (Optional<InstrProfOptions> Options =
1211               getInstrProfOptions(CodeGenOpts, LangOpts))
1212         PB.registerPipelineStartEPCallback([Options](ModulePassManager &MPM) {
1213           MPM.addPass(InstrProfiling(*Options, false));
1214         });
1215 
1216       if (IsThinLTO) {
1217         MPM = PB.buildThinLTOPreLinkDefaultPipeline(
1218             Level, CodeGenOpts.DebugPassManager);
1219         MPM.addPass(CanonicalizeAliasesPass());
1220         MPM.addPass(NameAnonGlobalPass());
1221       } else if (IsLTO) {
1222         MPM = PB.buildLTOPreLinkDefaultPipeline(Level,
1223                                                 CodeGenOpts.DebugPassManager);
1224         MPM.addPass(CanonicalizeAliasesPass());
1225         MPM.addPass(NameAnonGlobalPass());
1226       } else {
1227         MPM = PB.buildPerModuleDefaultPipeline(Level,
1228                                                CodeGenOpts.DebugPassManager);
1229       }
1230     }
1231 
1232     if (CodeGenOpts.SanitizeCoverageType ||
1233         CodeGenOpts.SanitizeCoverageIndirectCalls ||
1234         CodeGenOpts.SanitizeCoverageTraceCmp) {
1235       auto SancovOpts = getSancovOptsFromCGOpts(CodeGenOpts);
1236       MPM.addPass(ModuleSanitizerCoveragePass(SancovOpts));
1237     }
1238 
1239     if (LangOpts.Sanitize.has(SanitizerKind::HWAddress)) {
1240       bool Recover = CodeGenOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
1241       MPM.addPass(HWAddressSanitizerPass(
1242           /*CompileKernel=*/false, Recover));
1243     }
1244     if (LangOpts.Sanitize.has(SanitizerKind::KernelHWAddress)) {
1245       MPM.addPass(HWAddressSanitizerPass(
1246           /*CompileKernel=*/true, /*Recover=*/true));
1247     }
1248 
1249     if (CodeGenOpts.OptimizationLevel == 0) {
1250       addSanitizersAtO0(MPM, TargetTriple, LangOpts, CodeGenOpts);
1251     }
1252   }
1253 
1254   // FIXME: We still use the legacy pass manager to do code generation. We
1255   // create that pass manager here and use it as needed below.
1256   legacy::PassManager CodeGenPasses;
1257   bool NeedCodeGen = false;
1258   std::unique_ptr<llvm::ToolOutputFile> ThinLinkOS, DwoOS;
1259 
1260   // Append any output we need to the pass manager.
1261   switch (Action) {
1262   case Backend_EmitNothing:
1263     break;
1264 
1265   case Backend_EmitBC:
1266     if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
1267       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
1268         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
1269         if (!ThinLinkOS)
1270           return;
1271       }
1272       TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1273                                CodeGenOpts.EnableSplitLTOUnit);
1274       MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
1275                                                            : nullptr));
1276     } else {
1277       // Emit a module summary by default for Regular LTO except for ld64
1278       // targets
1279       bool EmitLTOSummary =
1280           (CodeGenOpts.PrepareForLTO &&
1281            !CodeGenOpts.DisableLLVMPasses &&
1282            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
1283                llvm::Triple::Apple);
1284       if (EmitLTOSummary) {
1285         if (!TheModule->getModuleFlag("ThinLTO"))
1286           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
1287         TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
1288                                  uint32_t(1));
1289       }
1290       MPM.addPass(
1291           BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists, EmitLTOSummary));
1292     }
1293     break;
1294 
1295   case Backend_EmitLL:
1296     MPM.addPass(PrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
1297     break;
1298 
1299   case Backend_EmitAssembly:
1300   case Backend_EmitMCNull:
1301   case Backend_EmitObj:
1302     NeedCodeGen = true;
1303     CodeGenPasses.add(
1304         createTargetTransformInfoWrapperPass(getTargetIRAnalysis()));
1305     if (!CodeGenOpts.SplitDwarfOutput.empty()) {
1306       DwoOS = openOutputFile(CodeGenOpts.SplitDwarfOutput);
1307       if (!DwoOS)
1308         return;
1309     }
1310     if (!AddEmitPasses(CodeGenPasses, Action, *OS,
1311                        DwoOS ? &DwoOS->os() : nullptr))
1312       // FIXME: Should we handle this error differently?
1313       return;
1314     break;
1315   }
1316 
1317   // Before executing passes, print the final values of the LLVM options.
1318   cl::PrintOptionValues();
1319 
1320   // Now that we have all of the passes ready, run them.
1321   {
1322     PrettyStackTraceString CrashInfo("Optimizer");
1323     MPM.run(*TheModule, MAM);
1324   }
1325 
1326   // Now if needed, run the legacy PM for codegen.
1327   if (NeedCodeGen) {
1328     PrettyStackTraceString CrashInfo("Code generation");
1329     CodeGenPasses.run(*TheModule);
1330   }
1331 
1332   if (ThinLinkOS)
1333     ThinLinkOS->keep();
1334   if (DwoOS)
1335     DwoOS->keep();
1336 }
1337 
1338 Expected<BitcodeModule> clang::FindThinLTOModule(MemoryBufferRef MBRef) {
1339   Expected<std::vector<BitcodeModule>> BMsOrErr = getBitcodeModuleList(MBRef);
1340   if (!BMsOrErr)
1341     return BMsOrErr.takeError();
1342 
1343   // The bitcode file may contain multiple modules, we want the one that is
1344   // marked as being the ThinLTO module.
1345   if (const BitcodeModule *Bm = FindThinLTOModule(*BMsOrErr))
1346     return *Bm;
1347 
1348   return make_error<StringError>("Could not find module summary",
1349                                  inconvertibleErrorCode());
1350 }
1351 
1352 BitcodeModule *clang::FindThinLTOModule(MutableArrayRef<BitcodeModule> BMs) {
1353   for (BitcodeModule &BM : BMs) {
1354     Expected<BitcodeLTOInfo> LTOInfo = BM.getLTOInfo();
1355     if (LTOInfo && LTOInfo->IsThinLTO)
1356       return &BM;
1357   }
1358   return nullptr;
1359 }
1360 
1361 static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
1362                               const HeaderSearchOptions &HeaderOpts,
1363                               const CodeGenOptions &CGOpts,
1364                               const clang::TargetOptions &TOpts,
1365                               const LangOptions &LOpts,
1366                               std::unique_ptr<raw_pwrite_stream> OS,
1367                               std::string SampleProfile,
1368                               std::string ProfileRemapping,
1369                               BackendAction Action) {
1370   StringMap<DenseMap<GlobalValue::GUID, GlobalValueSummary *>>
1371       ModuleToDefinedGVSummaries;
1372   CombinedIndex->collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
1373 
1374   setCommandLineOpts(CGOpts);
1375 
1376   // We can simply import the values mentioned in the combined index, since
1377   // we should only invoke this using the individual indexes written out
1378   // via a WriteIndexesThinBackend.
1379   FunctionImporter::ImportMapTy ImportList;
1380   for (auto &GlobalList : *CombinedIndex) {
1381     // Ignore entries for undefined references.
1382     if (GlobalList.second.SummaryList.empty())
1383       continue;
1384 
1385     auto GUID = GlobalList.first;
1386     for (auto &Summary : GlobalList.second.SummaryList) {
1387       // Skip the summaries for the importing module. These are included to
1388       // e.g. record required linkage changes.
1389       if (Summary->modulePath() == M->getModuleIdentifier())
1390         continue;
1391       // Add an entry to provoke importing by thinBackend.
1392       ImportList[Summary->modulePath()].insert(GUID);
1393     }
1394   }
1395 
1396   std::vector<std::unique_ptr<llvm::MemoryBuffer>> OwnedImports;
1397   MapVector<llvm::StringRef, llvm::BitcodeModule> ModuleMap;
1398 
1399   for (auto &I : ImportList) {
1400     ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> MBOrErr =
1401         llvm::MemoryBuffer::getFile(I.first());
1402     if (!MBOrErr) {
1403       errs() << "Error loading imported file '" << I.first()
1404              << "': " << MBOrErr.getError().message() << "\n";
1405       return;
1406     }
1407 
1408     Expected<BitcodeModule> BMOrErr = FindThinLTOModule(**MBOrErr);
1409     if (!BMOrErr) {
1410       handleAllErrors(BMOrErr.takeError(), [&](ErrorInfoBase &EIB) {
1411         errs() << "Error loading imported file '" << I.first()
1412                << "': " << EIB.message() << '\n';
1413       });
1414       return;
1415     }
1416     ModuleMap.insert({I.first(), *BMOrErr});
1417 
1418     OwnedImports.push_back(std::move(*MBOrErr));
1419   }
1420   auto AddStream = [&](size_t Task) {
1421     return std::make_unique<lto::NativeObjectStream>(std::move(OS));
1422   };
1423   lto::Config Conf;
1424   if (CGOpts.SaveTempsFilePrefix != "") {
1425     if (Error E = Conf.addSaveTemps(CGOpts.SaveTempsFilePrefix + ".",
1426                                     /* UseInputModulePath */ false)) {
1427       handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1428         errs() << "Error setting up ThinLTO save-temps: " << EIB.message()
1429                << '\n';
1430       });
1431     }
1432   }
1433   Conf.CPU = TOpts.CPU;
1434   Conf.CodeModel = getCodeModel(CGOpts);
1435   Conf.MAttrs = TOpts.Features;
1436   Conf.RelocModel = CGOpts.RelocationModel;
1437   Conf.CGOptLevel = getCGOptLevel(CGOpts);
1438   Conf.OptLevel = CGOpts.OptimizationLevel;
1439   initTargetOptions(Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
1440   Conf.SampleProfile = std::move(SampleProfile);
1441   Conf.PTO.LoopUnrolling = CGOpts.UnrollLoops;
1442   // For historical reasons, loop interleaving is set to mirror setting for loop
1443   // unrolling.
1444   Conf.PTO.LoopInterleaving = CGOpts.UnrollLoops;
1445   Conf.PTO.LoopVectorization = CGOpts.VectorizeLoop;
1446   Conf.PTO.SLPVectorization = CGOpts.VectorizeSLP;
1447 
1448   // Context sensitive profile.
1449   if (CGOpts.hasProfileCSIRInstr()) {
1450     Conf.RunCSIRInstr = true;
1451     Conf.CSIRProfile = std::move(CGOpts.InstrProfileOutput);
1452   } else if (CGOpts.hasProfileCSIRUse()) {
1453     Conf.RunCSIRInstr = false;
1454     Conf.CSIRProfile = std::move(CGOpts.ProfileInstrumentUsePath);
1455   }
1456 
1457   Conf.ProfileRemapping = std::move(ProfileRemapping);
1458   Conf.UseNewPM = CGOpts.ExperimentalNewPassManager;
1459   Conf.DebugPassManager = CGOpts.DebugPassManager;
1460   Conf.RemarksWithHotness = CGOpts.DiagnosticsWithHotness;
1461   Conf.RemarksFilename = CGOpts.OptRecordFile;
1462   Conf.RemarksPasses = CGOpts.OptRecordPasses;
1463   Conf.RemarksFormat = CGOpts.OptRecordFormat;
1464   Conf.SplitDwarfFile = CGOpts.SplitDwarfFile;
1465   Conf.SplitDwarfOutput = CGOpts.SplitDwarfOutput;
1466   switch (Action) {
1467   case Backend_EmitNothing:
1468     Conf.PreCodeGenModuleHook = [](size_t Task, const Module &Mod) {
1469       return false;
1470     };
1471     break;
1472   case Backend_EmitLL:
1473     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1474       M->print(*OS, nullptr, CGOpts.EmitLLVMUseLists);
1475       return false;
1476     };
1477     break;
1478   case Backend_EmitBC:
1479     Conf.PreCodeGenModuleHook = [&](size_t Task, const Module &Mod) {
1480       WriteBitcodeToFile(*M, *OS, CGOpts.EmitLLVMUseLists);
1481       return false;
1482     };
1483     break;
1484   default:
1485     Conf.CGFileType = getCodeGenFileType(Action);
1486     break;
1487   }
1488   if (Error E = thinBackend(
1489           Conf, -1, AddStream, *M, *CombinedIndex, ImportList,
1490           ModuleToDefinedGVSummaries[M->getModuleIdentifier()], ModuleMap)) {
1491     handleAllErrors(std::move(E), [&](ErrorInfoBase &EIB) {
1492       errs() << "Error running ThinLTO backend: " << EIB.message() << '\n';
1493     });
1494   }
1495 }
1496 
1497 void clang::EmitBackendOutput(DiagnosticsEngine &Diags,
1498                               const HeaderSearchOptions &HeaderOpts,
1499                               const CodeGenOptions &CGOpts,
1500                               const clang::TargetOptions &TOpts,
1501                               const LangOptions &LOpts,
1502                               const llvm::DataLayout &TDesc, Module *M,
1503                               BackendAction Action,
1504                               std::unique_ptr<raw_pwrite_stream> OS) {
1505 
1506   llvm::TimeTraceScope TimeScope("Backend");
1507 
1508   std::unique_ptr<llvm::Module> EmptyModule;
1509   if (!CGOpts.ThinLTOIndexFile.empty()) {
1510     // If we are performing a ThinLTO importing compile, load the function index
1511     // into memory and pass it into runThinLTOBackend, which will run the
1512     // function importer and invoke LTO passes.
1513     Expected<std::unique_ptr<ModuleSummaryIndex>> IndexOrErr =
1514         llvm::getModuleSummaryIndexForFile(CGOpts.ThinLTOIndexFile,
1515                                            /*IgnoreEmptyThinLTOIndexFile*/true);
1516     if (!IndexOrErr) {
1517       logAllUnhandledErrors(IndexOrErr.takeError(), errs(),
1518                             "Error loading index file '" +
1519                             CGOpts.ThinLTOIndexFile + "': ");
1520       return;
1521     }
1522     std::unique_ptr<ModuleSummaryIndex> CombinedIndex = std::move(*IndexOrErr);
1523     // A null CombinedIndex means we should skip ThinLTO compilation
1524     // (LLVM will optionally ignore empty index files, returning null instead
1525     // of an error).
1526     if (CombinedIndex) {
1527       if (!CombinedIndex->skipModuleByDistributedBackend()) {
1528         runThinLTOBackend(CombinedIndex.get(), M, HeaderOpts, CGOpts, TOpts,
1529                           LOpts, std::move(OS), CGOpts.SampleProfileFile,
1530                           CGOpts.ProfileRemappingFile, Action);
1531         return;
1532       }
1533       // Distributed indexing detected that nothing from the module is needed
1534       // for the final linking. So we can skip the compilation. We sill need to
1535       // output an empty object file to make sure that a linker does not fail
1536       // trying to read it. Also for some features, like CFI, we must skip
1537       // the compilation as CombinedIndex does not contain all required
1538       // information.
1539       EmptyModule = std::make_unique<llvm::Module>("empty", M->getContext());
1540       EmptyModule->setTargetTriple(M->getTargetTriple());
1541       M = EmptyModule.get();
1542     }
1543   }
1544 
1545   EmitAssemblyHelper AsmHelper(Diags, HeaderOpts, CGOpts, TOpts, LOpts, M);
1546 
1547   if (CGOpts.ExperimentalNewPassManager)
1548     AsmHelper.EmitAssemblyWithNewPassManager(Action, std::move(OS));
1549   else
1550     AsmHelper.EmitAssembly(Action, std::move(OS));
1551 
1552   // Verify clang's TargetInfo DataLayout against the LLVM TargetMachine's
1553   // DataLayout.
1554   if (AsmHelper.TM) {
1555     std::string DLDesc = M->getDataLayout().getStringRepresentation();
1556     if (DLDesc != TDesc.getStringRepresentation()) {
1557       unsigned DiagID = Diags.getCustomDiagID(
1558           DiagnosticsEngine::Error, "backend data layout '%0' does not match "
1559                                     "expected target description '%1'");
1560       Diags.Report(DiagID) << DLDesc << TDesc.getStringRepresentation();
1561     }
1562   }
1563 }
1564 
1565 // With -fembed-bitcode, save a copy of the llvm IR as data in the
1566 // __LLVM,__bitcode section.
1567 void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts,
1568                          llvm::MemoryBufferRef Buf) {
1569   if (CGOpts.getEmbedBitcode() == CodeGenOptions::Embed_Off)
1570     return;
1571   llvm::EmbedBitcodeInModule(
1572       *M, Buf, CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Marker,
1573       CGOpts.getEmbedBitcode() != CodeGenOptions::Embed_Bitcode,
1574       &CGOpts.CmdArgs);
1575 }
1576