xref: /freebsd/contrib/llvm-project/llvm/lib/LTO/LTOBackend.cpp (revision 85868e8a1daeaae7a0e48effb2ea2310ae3b02c6)
1 //===-LTOBackend.cpp - LLVM Link Time Optimizer Backend -------------------===//
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 // This file implements the "backend" phase of LTO, i.e. it performs
10 // optimization and code generation on a loaded module. It is generally used
11 // internally by the LTO class but can also be used independently, for example
12 // to implement a standalone ThinLTO backend.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "llvm/LTO/LTOBackend.h"
17 #include "llvm/Analysis/AliasAnalysis.h"
18 #include "llvm/Analysis/CGSCCPassManager.h"
19 #include "llvm/Analysis/TargetLibraryInfo.h"
20 #include "llvm/Analysis/TargetTransformInfo.h"
21 #include "llvm/Bitcode/BitcodeReader.h"
22 #include "llvm/Bitcode/BitcodeWriter.h"
23 #include "llvm/IR/LegacyPassManager.h"
24 #include "llvm/IR/PassManager.h"
25 #include "llvm/IR/RemarkStreamer.h"
26 #include "llvm/IR/Verifier.h"
27 #include "llvm/LTO/LTO.h"
28 #include "llvm/MC/SubtargetFeature.h"
29 #include "llvm/Object/ModuleSymbolTable.h"
30 #include "llvm/Passes/PassBuilder.h"
31 #include "llvm/Passes/StandardInstrumentations.h"
32 #include "llvm/Support/Error.h"
33 #include "llvm/Support/FileSystem.h"
34 #include "llvm/Support/MemoryBuffer.h"
35 #include "llvm/Support/Path.h"
36 #include "llvm/Support/Program.h"
37 #include "llvm/Support/TargetRegistry.h"
38 #include "llvm/Support/ThreadPool.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Target/TargetMachine.h"
41 #include "llvm/Transforms/IPO.h"
42 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
43 #include "llvm/Transforms/Scalar/LoopPassManager.h"
44 #include "llvm/Transforms/Utils/FunctionImportUtils.h"
45 #include "llvm/Transforms/Utils/SplitModule.h"
46 
47 using namespace llvm;
48 using namespace lto;
49 
50 LLVM_ATTRIBUTE_NORETURN static void reportOpenError(StringRef Path, Twine Msg) {
51   errs() << "failed to open " << Path << ": " << Msg << '\n';
52   errs().flush();
53   exit(1);
54 }
55 
56 Error Config::addSaveTemps(std::string OutputFileName,
57                            bool UseInputModulePath) {
58   ShouldDiscardValueNames = false;
59 
60   std::error_code EC;
61   ResolutionFile = std::make_unique<raw_fd_ostream>(
62       OutputFileName + "resolution.txt", EC, sys::fs::OpenFlags::OF_Text);
63   if (EC)
64     return errorCodeToError(EC);
65 
66   auto setHook = [&](std::string PathSuffix, ModuleHookFn &Hook) {
67     // Keep track of the hook provided by the linker, which also needs to run.
68     ModuleHookFn LinkerHook = Hook;
69     Hook = [=](unsigned Task, const Module &M) {
70       // If the linker's hook returned false, we need to pass that result
71       // through.
72       if (LinkerHook && !LinkerHook(Task, M))
73         return false;
74 
75       std::string PathPrefix;
76       // If this is the combined module (not a ThinLTO backend compile) or the
77       // user hasn't requested using the input module's path, emit to a file
78       // named from the provided OutputFileName with the Task ID appended.
79       if (M.getModuleIdentifier() == "ld-temp.o" || !UseInputModulePath) {
80         PathPrefix = OutputFileName;
81         if (Task != (unsigned)-1)
82           PathPrefix += utostr(Task) + ".";
83       } else
84         PathPrefix = M.getModuleIdentifier() + ".";
85       std::string Path = PathPrefix + PathSuffix + ".bc";
86       std::error_code EC;
87       raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::OF_None);
88       // Because -save-temps is a debugging feature, we report the error
89       // directly and exit.
90       if (EC)
91         reportOpenError(Path, EC.message());
92       WriteBitcodeToFile(M, OS, /*ShouldPreserveUseListOrder=*/false);
93       return true;
94     };
95   };
96 
97   setHook("0.preopt", PreOptModuleHook);
98   setHook("1.promote", PostPromoteModuleHook);
99   setHook("2.internalize", PostInternalizeModuleHook);
100   setHook("3.import", PostImportModuleHook);
101   setHook("4.opt", PostOptModuleHook);
102   setHook("5.precodegen", PreCodeGenModuleHook);
103 
104   CombinedIndexHook = [=](const ModuleSummaryIndex &Index) {
105     std::string Path = OutputFileName + "index.bc";
106     std::error_code EC;
107     raw_fd_ostream OS(Path, EC, sys::fs::OpenFlags::OF_None);
108     // Because -save-temps is a debugging feature, we report the error
109     // directly and exit.
110     if (EC)
111       reportOpenError(Path, EC.message());
112     WriteIndexToFile(Index, OS);
113 
114     Path = OutputFileName + "index.dot";
115     raw_fd_ostream OSDot(Path, EC, sys::fs::OpenFlags::OF_None);
116     if (EC)
117       reportOpenError(Path, EC.message());
118     Index.exportToDot(OSDot);
119     return true;
120   };
121 
122   return Error::success();
123 }
124 
125 namespace {
126 
127 std::unique_ptr<TargetMachine>
128 createTargetMachine(Config &Conf, const Target *TheTarget, Module &M) {
129   StringRef TheTriple = M.getTargetTriple();
130   SubtargetFeatures Features;
131   Features.getDefaultSubtargetFeatures(Triple(TheTriple));
132   for (const std::string &A : Conf.MAttrs)
133     Features.AddFeature(A);
134 
135   Reloc::Model RelocModel;
136   if (Conf.RelocModel)
137     RelocModel = *Conf.RelocModel;
138   else
139     RelocModel =
140         M.getPICLevel() == PICLevel::NotPIC ? Reloc::Static : Reloc::PIC_;
141 
142   Optional<CodeModel::Model> CodeModel;
143   if (Conf.CodeModel)
144     CodeModel = *Conf.CodeModel;
145   else
146     CodeModel = M.getCodeModel();
147 
148   return std::unique_ptr<TargetMachine>(TheTarget->createTargetMachine(
149       TheTriple, Conf.CPU, Features.getString(), Conf.Options, RelocModel,
150       CodeModel, Conf.CGOptLevel));
151 }
152 
153 static void runNewPMPasses(Config &Conf, Module &Mod, TargetMachine *TM,
154                            unsigned OptLevel, bool IsThinLTO,
155                            ModuleSummaryIndex *ExportSummary,
156                            const ModuleSummaryIndex *ImportSummary) {
157   Optional<PGOOptions> PGOOpt;
158   if (!Conf.SampleProfile.empty())
159     PGOOpt = PGOOptions(Conf.SampleProfile, "", Conf.ProfileRemapping,
160                         PGOOptions::SampleUse, PGOOptions::NoCSAction, true);
161   else if (Conf.RunCSIRInstr) {
162     PGOOpt = PGOOptions("", Conf.CSIRProfile, Conf.ProfileRemapping,
163                         PGOOptions::IRUse, PGOOptions::CSIRInstr);
164   } else if (!Conf.CSIRProfile.empty()) {
165     PGOOpt = PGOOptions(Conf.CSIRProfile, "", Conf.ProfileRemapping,
166                         PGOOptions::IRUse, PGOOptions::CSIRUse);
167   }
168 
169   PassInstrumentationCallbacks PIC;
170   StandardInstrumentations SI;
171   SI.registerCallbacks(PIC);
172   PassBuilder PB(TM, PipelineTuningOptions(),PGOOpt, &PIC);
173   AAManager AA;
174 
175   // Parse a custom AA pipeline if asked to.
176   if (auto Err = PB.parseAAPipeline(AA, "default"))
177     report_fatal_error("Error parsing default AA pipeline");
178 
179   LoopAnalysisManager LAM(Conf.DebugPassManager);
180   FunctionAnalysisManager FAM(Conf.DebugPassManager);
181   CGSCCAnalysisManager CGAM(Conf.DebugPassManager);
182   ModuleAnalysisManager MAM(Conf.DebugPassManager);
183 
184   // Register the AA manager first so that our version is the one used.
185   FAM.registerPass([&] { return std::move(AA); });
186 
187   // Register all the basic analyses with the managers.
188   PB.registerModuleAnalyses(MAM);
189   PB.registerCGSCCAnalyses(CGAM);
190   PB.registerFunctionAnalyses(FAM);
191   PB.registerLoopAnalyses(LAM);
192   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
193 
194   ModulePassManager MPM(Conf.DebugPassManager);
195   // FIXME (davide): verify the input.
196 
197   PassBuilder::OptimizationLevel OL;
198 
199   switch (OptLevel) {
200   default:
201     llvm_unreachable("Invalid optimization level");
202   case 0:
203     OL = PassBuilder::O0;
204     break;
205   case 1:
206     OL = PassBuilder::O1;
207     break;
208   case 2:
209     OL = PassBuilder::O2;
210     break;
211   case 3:
212     OL = PassBuilder::O3;
213     break;
214   }
215 
216   if (IsThinLTO)
217     MPM = PB.buildThinLTODefaultPipeline(OL, Conf.DebugPassManager,
218                                          ImportSummary);
219   else
220     MPM = PB.buildLTODefaultPipeline(OL, Conf.DebugPassManager, ExportSummary);
221   MPM.run(Mod, MAM);
222 
223   // FIXME (davide): verify the output.
224 }
225 
226 static void runNewPMCustomPasses(Module &Mod, TargetMachine *TM,
227                                  std::string PipelineDesc,
228                                  std::string AAPipelineDesc,
229                                  bool DisableVerify) {
230   PassBuilder PB(TM);
231   AAManager AA;
232 
233   // Parse a custom AA pipeline if asked to.
234   if (!AAPipelineDesc.empty())
235     if (auto Err = PB.parseAAPipeline(AA, AAPipelineDesc))
236       report_fatal_error("unable to parse AA pipeline description '" +
237                          AAPipelineDesc + "': " + toString(std::move(Err)));
238 
239   LoopAnalysisManager LAM;
240   FunctionAnalysisManager FAM;
241   CGSCCAnalysisManager CGAM;
242   ModuleAnalysisManager MAM;
243 
244   // Register the AA manager first so that our version is the one used.
245   FAM.registerPass([&] { return std::move(AA); });
246 
247   // Register all the basic analyses with the managers.
248   PB.registerModuleAnalyses(MAM);
249   PB.registerCGSCCAnalyses(CGAM);
250   PB.registerFunctionAnalyses(FAM);
251   PB.registerLoopAnalyses(LAM);
252   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
253 
254   ModulePassManager MPM;
255 
256   // Always verify the input.
257   MPM.addPass(VerifierPass());
258 
259   // Now, add all the passes we've been requested to.
260   if (auto Err = PB.parsePassPipeline(MPM, PipelineDesc))
261     report_fatal_error("unable to parse pass pipeline description '" +
262                        PipelineDesc + "': " + toString(std::move(Err)));
263 
264   if (!DisableVerify)
265     MPM.addPass(VerifierPass());
266   MPM.run(Mod, MAM);
267 }
268 
269 static void runOldPMPasses(Config &Conf, Module &Mod, TargetMachine *TM,
270                            bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
271                            const ModuleSummaryIndex *ImportSummary) {
272   legacy::PassManager passes;
273   passes.add(createTargetTransformInfoWrapperPass(TM->getTargetIRAnalysis()));
274 
275   PassManagerBuilder PMB;
276   PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM->getTargetTriple()));
277   PMB.Inliner = createFunctionInliningPass();
278   PMB.ExportSummary = ExportSummary;
279   PMB.ImportSummary = ImportSummary;
280   // Unconditionally verify input since it is not verified before this
281   // point and has unknown origin.
282   PMB.VerifyInput = true;
283   PMB.VerifyOutput = !Conf.DisableVerify;
284   PMB.LoopVectorize = true;
285   PMB.SLPVectorize = true;
286   PMB.OptLevel = Conf.OptLevel;
287   PMB.PGOSampleUse = Conf.SampleProfile;
288   PMB.EnablePGOCSInstrGen = Conf.RunCSIRInstr;
289   if (!Conf.RunCSIRInstr && !Conf.CSIRProfile.empty()) {
290     PMB.EnablePGOCSInstrUse = true;
291     PMB.PGOInstrUse = Conf.CSIRProfile;
292   }
293   if (IsThinLTO)
294     PMB.populateThinLTOPassManager(passes);
295   else
296     PMB.populateLTOPassManager(passes);
297   passes.run(Mod);
298 }
299 
300 bool opt(Config &Conf, TargetMachine *TM, unsigned Task, Module &Mod,
301          bool IsThinLTO, ModuleSummaryIndex *ExportSummary,
302          const ModuleSummaryIndex *ImportSummary) {
303   // FIXME: Plumb the combined index into the new pass manager.
304   if (!Conf.OptPipeline.empty())
305     runNewPMCustomPasses(Mod, TM, Conf.OptPipeline, Conf.AAPipeline,
306                          Conf.DisableVerify);
307   else if (Conf.UseNewPM)
308     runNewPMPasses(Conf, Mod, TM, Conf.OptLevel, IsThinLTO, ExportSummary,
309                    ImportSummary);
310   else
311     runOldPMPasses(Conf, Mod, TM, IsThinLTO, ExportSummary, ImportSummary);
312   return !Conf.PostOptModuleHook || Conf.PostOptModuleHook(Task, Mod);
313 }
314 
315 void codegen(Config &Conf, TargetMachine *TM, AddStreamFn AddStream,
316              unsigned Task, Module &Mod) {
317   if (Conf.PreCodeGenModuleHook && !Conf.PreCodeGenModuleHook(Task, Mod))
318     return;
319 
320   std::unique_ptr<ToolOutputFile> DwoOut;
321   SmallString<1024> DwoFile(Conf.SplitDwarfOutput);
322   if (!Conf.DwoDir.empty()) {
323     std::error_code EC;
324     if (auto EC = llvm::sys::fs::create_directories(Conf.DwoDir))
325       report_fatal_error("Failed to create directory " + Conf.DwoDir + ": " +
326                          EC.message());
327 
328     DwoFile = Conf.DwoDir;
329     sys::path::append(DwoFile, std::to_string(Task) + ".dwo");
330     TM->Options.MCOptions.SplitDwarfFile = DwoFile.str().str();
331   } else
332     TM->Options.MCOptions.SplitDwarfFile = Conf.SplitDwarfFile;
333 
334   if (!DwoFile.empty()) {
335     std::error_code EC;
336     DwoOut = std::make_unique<ToolOutputFile>(DwoFile, EC, sys::fs::OF_None);
337     if (EC)
338       report_fatal_error("Failed to open " + DwoFile + ": " + EC.message());
339   }
340 
341   auto Stream = AddStream(Task);
342   legacy::PassManager CodeGenPasses;
343   if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
344                               DwoOut ? &DwoOut->os() : nullptr,
345                               Conf.CGFileType))
346     report_fatal_error("Failed to setup codegen");
347   CodeGenPasses.run(Mod);
348 
349   if (DwoOut)
350     DwoOut->keep();
351 }
352 
353 void splitCodeGen(Config &C, TargetMachine *TM, AddStreamFn AddStream,
354                   unsigned ParallelCodeGenParallelismLevel,
355                   std::unique_ptr<Module> Mod) {
356   ThreadPool CodegenThreadPool(ParallelCodeGenParallelismLevel);
357   unsigned ThreadCount = 0;
358   const Target *T = &TM->getTarget();
359 
360   SplitModule(
361       std::move(Mod), ParallelCodeGenParallelismLevel,
362       [&](std::unique_ptr<Module> MPart) {
363         // We want to clone the module in a new context to multi-thread the
364         // codegen. We do it by serializing partition modules to bitcode
365         // (while still on the main thread, in order to avoid data races) and
366         // spinning up new threads which deserialize the partitions into
367         // separate contexts.
368         // FIXME: Provide a more direct way to do this in LLVM.
369         SmallString<0> BC;
370         raw_svector_ostream BCOS(BC);
371         WriteBitcodeToFile(*MPart, BCOS);
372 
373         // Enqueue the task
374         CodegenThreadPool.async(
375             [&](const SmallString<0> &BC, unsigned ThreadId) {
376               LTOLLVMContext Ctx(C);
377               Expected<std::unique_ptr<Module>> MOrErr = parseBitcodeFile(
378                   MemoryBufferRef(StringRef(BC.data(), BC.size()), "ld-temp.o"),
379                   Ctx);
380               if (!MOrErr)
381                 report_fatal_error("Failed to read bitcode");
382               std::unique_ptr<Module> MPartInCtx = std::move(MOrErr.get());
383 
384               std::unique_ptr<TargetMachine> TM =
385                   createTargetMachine(C, T, *MPartInCtx);
386 
387               codegen(C, TM.get(), AddStream, ThreadId, *MPartInCtx);
388             },
389             // Pass BC using std::move to ensure that it get moved rather than
390             // copied into the thread's context.
391             std::move(BC), ThreadCount++);
392       },
393       false);
394 
395   // Because the inner lambda (which runs in a worker thread) captures our local
396   // variables, we need to wait for the worker threads to terminate before we
397   // can leave the function scope.
398   CodegenThreadPool.wait();
399 }
400 
401 Expected<const Target *> initAndLookupTarget(Config &C, Module &Mod) {
402   if (!C.OverrideTriple.empty())
403     Mod.setTargetTriple(C.OverrideTriple);
404   else if (Mod.getTargetTriple().empty())
405     Mod.setTargetTriple(C.DefaultTriple);
406 
407   std::string Msg;
408   const Target *T = TargetRegistry::lookupTarget(Mod.getTargetTriple(), Msg);
409   if (!T)
410     return make_error<StringError>(Msg, inconvertibleErrorCode());
411   return T;
412 }
413 
414 }
415 
416 static Error
417 finalizeOptimizationRemarks(std::unique_ptr<ToolOutputFile> DiagOutputFile) {
418   // Make sure we flush the diagnostic remarks file in case the linker doesn't
419   // call the global destructors before exiting.
420   if (!DiagOutputFile)
421     return Error::success();
422   DiagOutputFile->keep();
423   DiagOutputFile->os().flush();
424   return Error::success();
425 }
426 
427 Error lto::backend(Config &C, AddStreamFn AddStream,
428                    unsigned ParallelCodeGenParallelismLevel,
429                    std::unique_ptr<Module> Mod,
430                    ModuleSummaryIndex &CombinedIndex) {
431   Expected<const Target *> TOrErr = initAndLookupTarget(C, *Mod);
432   if (!TOrErr)
433     return TOrErr.takeError();
434 
435   std::unique_ptr<TargetMachine> TM = createTargetMachine(C, *TOrErr, *Mod);
436 
437   // Setup optimization remarks.
438   auto DiagFileOrErr = lto::setupOptimizationRemarks(
439       Mod->getContext(), C.RemarksFilename, C.RemarksPasses, C.RemarksFormat,
440       C.RemarksWithHotness);
441   if (!DiagFileOrErr)
442     return DiagFileOrErr.takeError();
443   auto DiagnosticOutputFile = std::move(*DiagFileOrErr);
444 
445   if (!C.CodeGenOnly) {
446     if (!opt(C, TM.get(), 0, *Mod, /*IsThinLTO=*/false,
447              /*ExportSummary=*/&CombinedIndex, /*ImportSummary=*/nullptr))
448       return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
449   }
450 
451   if (ParallelCodeGenParallelismLevel == 1) {
452     codegen(C, TM.get(), AddStream, 0, *Mod);
453   } else {
454     splitCodeGen(C, TM.get(), AddStream, ParallelCodeGenParallelismLevel,
455                  std::move(Mod));
456   }
457   return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
458 }
459 
460 static void dropDeadSymbols(Module &Mod, const GVSummaryMapTy &DefinedGlobals,
461                             const ModuleSummaryIndex &Index) {
462   std::vector<GlobalValue*> DeadGVs;
463   for (auto &GV : Mod.global_values())
464     if (GlobalValueSummary *GVS = DefinedGlobals.lookup(GV.getGUID()))
465       if (!Index.isGlobalValueLive(GVS)) {
466         DeadGVs.push_back(&GV);
467         convertToDeclaration(GV);
468       }
469 
470   // Now that all dead bodies have been dropped, delete the actual objects
471   // themselves when possible.
472   for (GlobalValue *GV : DeadGVs) {
473     GV->removeDeadConstantUsers();
474     // Might reference something defined in native object (i.e. dropped a
475     // non-prevailing IR def, but we need to keep the declaration).
476     if (GV->use_empty())
477       GV->eraseFromParent();
478   }
479 }
480 
481 Error lto::thinBackend(Config &Conf, unsigned Task, AddStreamFn AddStream,
482                        Module &Mod, const ModuleSummaryIndex &CombinedIndex,
483                        const FunctionImporter::ImportMapTy &ImportList,
484                        const GVSummaryMapTy &DefinedGlobals,
485                        MapVector<StringRef, BitcodeModule> &ModuleMap) {
486   Expected<const Target *> TOrErr = initAndLookupTarget(Conf, Mod);
487   if (!TOrErr)
488     return TOrErr.takeError();
489 
490   std::unique_ptr<TargetMachine> TM = createTargetMachine(Conf, *TOrErr, Mod);
491 
492   // Setup optimization remarks.
493   auto DiagFileOrErr = lto::setupOptimizationRemarks(
494       Mod.getContext(), Conf.RemarksFilename, Conf.RemarksPasses,
495       Conf.RemarksFormat, Conf.RemarksWithHotness, Task);
496   if (!DiagFileOrErr)
497     return DiagFileOrErr.takeError();
498   auto DiagnosticOutputFile = std::move(*DiagFileOrErr);
499 
500   if (Conf.CodeGenOnly) {
501     codegen(Conf, TM.get(), AddStream, Task, Mod);
502     return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
503   }
504 
505   if (Conf.PreOptModuleHook && !Conf.PreOptModuleHook(Task, Mod))
506     return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
507 
508   renameModuleForThinLTO(Mod, CombinedIndex);
509 
510   dropDeadSymbols(Mod, DefinedGlobals, CombinedIndex);
511 
512   thinLTOResolvePrevailingInModule(Mod, DefinedGlobals);
513 
514   if (Conf.PostPromoteModuleHook && !Conf.PostPromoteModuleHook(Task, Mod))
515     return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
516 
517   if (!DefinedGlobals.empty())
518     thinLTOInternalizeModule(Mod, DefinedGlobals);
519 
520   if (Conf.PostInternalizeModuleHook &&
521       !Conf.PostInternalizeModuleHook(Task, Mod))
522     return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
523 
524   auto ModuleLoader = [&](StringRef Identifier) {
525     assert(Mod.getContext().isODRUniquingDebugTypes() &&
526            "ODR Type uniquing should be enabled on the context");
527     auto I = ModuleMap.find(Identifier);
528     assert(I != ModuleMap.end());
529     return I->second.getLazyModule(Mod.getContext(),
530                                    /*ShouldLazyLoadMetadata=*/true,
531                                    /*IsImporting*/ true);
532   };
533 
534   FunctionImporter Importer(CombinedIndex, ModuleLoader);
535   if (Error Err = Importer.importFunctions(Mod, ImportList).takeError())
536     return Err;
537 
538   if (Conf.PostImportModuleHook && !Conf.PostImportModuleHook(Task, Mod))
539     return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
540 
541   if (!opt(Conf, TM.get(), Task, Mod, /*IsThinLTO=*/true,
542            /*ExportSummary=*/nullptr, /*ImportSummary=*/&CombinedIndex))
543     return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
544 
545   codegen(Conf, TM.get(), AddStream, Task, Mod);
546   return finalizeOptimizationRemarks(std::move(DiagnosticOutputFile));
547 }
548