LTOCodeGenerator.cpp revision 360784 
1//===-LTOCodeGenerator.cpp - LLVM Link Time Optimizer ---------------------===//
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 Link Time Optimization library. This library is
10// intended to be used by linker to optimize code at link time.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/LTO/legacy/LTOCodeGenerator.h"
15
16#include "llvm/ADT/Statistic.h"
17#include "llvm/ADT/StringExtras.h"
18#include "llvm/Analysis/Passes.h"
19#include "llvm/Analysis/TargetLibraryInfo.h"
20#include "llvm/Analysis/TargetTransformInfo.h"
21#include "llvm/Bitcode/BitcodeWriter.h"
22#include "llvm/CodeGen/ParallelCG.h"
23#include "llvm/CodeGen/TargetSubtargetInfo.h"
24#include "llvm/Config/config.h"
25#include "llvm/IR/Constants.h"
26#include "llvm/IR/DataLayout.h"
27#include "llvm/IR/DebugInfo.h"
28#include "llvm/IR/DerivedTypes.h"
29#include "llvm/IR/DiagnosticInfo.h"
30#include "llvm/IR/DiagnosticPrinter.h"
31#include "llvm/IR/LLVMContext.h"
32#include "llvm/IR/LegacyPassManager.h"
33#include "llvm/IR/Mangler.h"
34#include "llvm/IR/Module.h"
35#include "llvm/IR/PassTimingInfo.h"
36#include "llvm/IR/RemarkStreamer.h"
37#include "llvm/IR/Verifier.h"
38#include "llvm/InitializePasses.h"
39#include "llvm/LTO/LTO.h"
40#include "llvm/LTO/legacy/LTOModule.h"
41#include "llvm/LTO/legacy/UpdateCompilerUsed.h"
42#include "llvm/Linker/Linker.h"
43#include "llvm/MC/MCAsmInfo.h"
44#include "llvm/MC/MCContext.h"
45#include "llvm/MC/SubtargetFeature.h"
46#include "llvm/Support/CommandLine.h"
47#include "llvm/Support/FileSystem.h"
48#include "llvm/Support/Host.h"
49#include "llvm/Support/MemoryBuffer.h"
50#include "llvm/Support/Signals.h"
51#include "llvm/Support/TargetRegistry.h"
52#include "llvm/Support/TargetSelect.h"
53#include "llvm/Support/ToolOutputFile.h"
54#include "llvm/Support/YAMLTraits.h"
55#include "llvm/Support/raw_ostream.h"
56#include "llvm/Target/TargetOptions.h"
57#include "llvm/Transforms/IPO.h"
58#include "llvm/Transforms/IPO/Internalize.h"
59#include "llvm/Transforms/IPO/PassManagerBuilder.h"
60#include "llvm/Transforms/ObjCARC.h"
61#include "llvm/Transforms/Utils/ModuleUtils.h"
62#include <system_error>
63using namespace llvm;
64
65const char* LTOCodeGenerator::getVersionString() {
66#ifdef LLVM_VERSION_INFO
67  return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
68#else
69  return PACKAGE_NAME " version " PACKAGE_VERSION;
70#endif
71}
72
73namespace llvm {
74cl::opt<bool> LTODiscardValueNames(
75    "lto-discard-value-names",
76    cl::desc("Strip names from Value during LTO (other than GlobalValue)."),
77#ifdef NDEBUG
78    cl::init(true),
79#else
80    cl::init(false),
81#endif
82    cl::Hidden);
83
84cl::opt<bool> RemarksWithHotness(
85    "lto-pass-remarks-with-hotness",
86    cl::desc("With PGO, include profile count in optimization remarks"),
87    cl::Hidden);
88
89cl::opt<std::string>
90    RemarksFilename("lto-pass-remarks-output",
91                    cl::desc("Output filename for pass remarks"),
92                    cl::value_desc("filename"));
93
94cl::opt<std::string>
95    RemarksPasses("lto-pass-remarks-filter",
96                  cl::desc("Only record optimization remarks from passes whose "
97                           "names match the given regular expression"),
98                  cl::value_desc("regex"));
99
100cl::opt<std::string> RemarksFormat(
101    "lto-pass-remarks-format",
102    cl::desc("The format used for serializing remarks (default: YAML)"),
103    cl::value_desc("format"), cl::init("yaml"));
104
105cl::opt<std::string> LTOStatsFile(
106    "lto-stats-file",
107    cl::desc("Save statistics to the specified file"),
108    cl::Hidden);
109}
110
111LTOCodeGenerator::LTOCodeGenerator(LLVMContext &Context)
112    : Context(Context), MergedModule(new Module("ld-temp.o", Context)),
113      TheLinker(new Linker(*MergedModule)) {
114  Context.setDiscardValueNames(LTODiscardValueNames);
115  Context.enableDebugTypeODRUniquing();
116  initializeLTOPasses();
117}
118
119LTOCodeGenerator::~LTOCodeGenerator() {}
120
121// Initialize LTO passes. Please keep this function in sync with
122// PassManagerBuilder::populateLTOPassManager(), and make sure all LTO
123// passes are initialized.
124void LTOCodeGenerator::initializeLTOPasses() {
125  PassRegistry &R = *PassRegistry::getPassRegistry();
126
127  initializeInternalizeLegacyPassPass(R);
128  initializeIPSCCPLegacyPassPass(R);
129  initializeGlobalOptLegacyPassPass(R);
130  initializeConstantMergeLegacyPassPass(R);
131  initializeDAHPass(R);
132  initializeInstructionCombiningPassPass(R);
133  initializeSimpleInlinerPass(R);
134  initializePruneEHPass(R);
135  initializeGlobalDCELegacyPassPass(R);
136  initializeArgPromotionPass(R);
137  initializeJumpThreadingPass(R);
138  initializeSROALegacyPassPass(R);
139  initializeAttributorLegacyPassPass(R);
140  initializePostOrderFunctionAttrsLegacyPassPass(R);
141  initializeReversePostOrderFunctionAttrsLegacyPassPass(R);
142  initializeGlobalsAAWrapperPassPass(R);
143  initializeLegacyLICMPassPass(R);
144  initializeMergedLoadStoreMotionLegacyPassPass(R);
145  initializeGVNLegacyPassPass(R);
146  initializeMemCpyOptLegacyPassPass(R);
147  initializeDCELegacyPassPass(R);
148  initializeCFGSimplifyPassPass(R);
149}
150
151void LTOCodeGenerator::setAsmUndefinedRefs(LTOModule *Mod) {
152  const std::vector<StringRef> &undefs = Mod->getAsmUndefinedRefs();
153  for (int i = 0, e = undefs.size(); i != e; ++i)
154    AsmUndefinedRefs.insert(undefs[i]);
155}
156
157bool LTOCodeGenerator::addModule(LTOModule *Mod) {
158  assert(&Mod->getModule().getContext() == &Context &&
159         "Expected module in same context");
160
161  bool ret = TheLinker->linkInModule(Mod->takeModule());
162  setAsmUndefinedRefs(Mod);
163
164  // We've just changed the input, so let's make sure we verify it.
165  HasVerifiedInput = false;
166
167  return !ret;
168}
169
170void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
171  assert(&Mod->getModule().getContext() == &Context &&
172         "Expected module in same context");
173
174  AsmUndefinedRefs.clear();
175
176  MergedModule = Mod->takeModule();
177  TheLinker = std::make_unique<Linker>(*MergedModule);
178  setAsmUndefinedRefs(&*Mod);
179
180  // We've just changed the input, so let's make sure we verify it.
181  HasVerifiedInput = false;
182}
183
184void LTOCodeGenerator::setTargetOptions(const TargetOptions &Options) {
185  this->Options = Options;
186}
187
188void LTOCodeGenerator::setDebugInfo(lto_debug_model Debug) {
189  switch (Debug) {
190  case LTO_DEBUG_MODEL_NONE:
191    EmitDwarfDebugInfo = false;
192    return;
193
194  case LTO_DEBUG_MODEL_DWARF:
195    EmitDwarfDebugInfo = true;
196    return;
197  }
198  llvm_unreachable("Unknown debug format!");
199}
200
201void LTOCodeGenerator::setOptLevel(unsigned Level) {
202  OptLevel = Level;
203  switch (OptLevel) {
204  case 0:
205    CGOptLevel = CodeGenOpt::None;
206    return;
207  case 1:
208    CGOptLevel = CodeGenOpt::Less;
209    return;
210  case 2:
211    CGOptLevel = CodeGenOpt::Default;
212    return;
213  case 3:
214    CGOptLevel = CodeGenOpt::Aggressive;
215    return;
216  }
217  llvm_unreachable("Unknown optimization level!");
218}
219
220bool LTOCodeGenerator::writeMergedModules(StringRef Path) {
221  if (!determineTarget())
222    return false;
223
224  // We always run the verifier once on the merged module.
225  verifyMergedModuleOnce();
226
227  // mark which symbols can not be internalized
228  applyScopeRestrictions();
229
230  // create output file
231  std::error_code EC;
232  ToolOutputFile Out(Path, EC, sys::fs::OF_None);
233  if (EC) {
234    std::string ErrMsg = "could not open bitcode file for writing: ";
235    ErrMsg += Path.str() + ": " + EC.message();
236    emitError(ErrMsg);
237    return false;
238  }
239
240  // write bitcode to it
241  WriteBitcodeToFile(*MergedModule, Out.os(), ShouldEmbedUselists);
242  Out.os().close();
243
244  if (Out.os().has_error()) {
245    std::string ErrMsg = "could not write bitcode file: ";
246    ErrMsg += Path.str() + ": " + Out.os().error().message();
247    emitError(ErrMsg);
248    Out.os().clear_error();
249    return false;
250  }
251
252  Out.keep();
253  return true;
254}
255
256bool LTOCodeGenerator::compileOptimizedToFile(const char **Name) {
257  // make unique temp output file to put generated code
258  SmallString<128> Filename;
259  int FD;
260
261  StringRef Extension
262      (FileType == CGFT_AssemblyFile ? "s" : "o");
263
264  std::error_code EC =
265      sys::fs::createTemporaryFile("lto-llvm", Extension, FD, Filename);
266  if (EC) {
267    emitError(EC.message());
268    return false;
269  }
270
271  // generate object file
272  ToolOutputFile objFile(Filename, FD);
273
274  bool genResult = compileOptimized(&objFile.os());
275  objFile.os().close();
276  if (objFile.os().has_error()) {
277    emitError((Twine("could not write object file: ") + Filename + ": " +
278               objFile.os().error().message())
279                  .str());
280    objFile.os().clear_error();
281    sys::fs::remove(Twine(Filename));
282    return false;
283  }
284
285  objFile.keep();
286  if (!genResult) {
287    sys::fs::remove(Twine(Filename));
288    return false;
289  }
290
291  NativeObjectPath = Filename.c_str();
292  *Name = NativeObjectPath.c_str();
293  return true;
294}
295
296std::unique_ptr<MemoryBuffer>
297LTOCodeGenerator::compileOptimized() {
298  const char *name;
299  if (!compileOptimizedToFile(&name))
300    return nullptr;
301
302  // read .o file into memory buffer
303  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
304      MemoryBuffer::getFile(name, -1, false);
305  if (std::error_code EC = BufferOrErr.getError()) {
306    emitError(EC.message());
307    sys::fs::remove(NativeObjectPath);
308    return nullptr;
309  }
310
311  // remove temp files
312  sys::fs::remove(NativeObjectPath);
313
314  return std::move(*BufferOrErr);
315}
316
317bool LTOCodeGenerator::compile_to_file(const char **Name, bool DisableVerify,
318                                       bool DisableInline,
319                                       bool DisableGVNLoadPRE,
320                                       bool DisableVectorization) {
321  if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
322                DisableVectorization))
323    return false;
324
325  return compileOptimizedToFile(Name);
326}
327
328std::unique_ptr<MemoryBuffer>
329LTOCodeGenerator::compile(bool DisableVerify, bool DisableInline,
330                          bool DisableGVNLoadPRE, bool DisableVectorization) {
331  if (!optimize(DisableVerify, DisableInline, DisableGVNLoadPRE,
332                DisableVectorization))
333    return nullptr;
334
335  return compileOptimized();
336}
337
338bool LTOCodeGenerator::determineTarget() {
339  if (TargetMach)
340    return true;
341
342  TripleStr = MergedModule->getTargetTriple();
343  if (TripleStr.empty()) {
344    TripleStr = sys::getDefaultTargetTriple();
345    MergedModule->setTargetTriple(TripleStr);
346  }
347  llvm::Triple Triple(TripleStr);
348
349  // create target machine from info for merged modules
350  std::string ErrMsg;
351  MArch = TargetRegistry::lookupTarget(TripleStr, ErrMsg);
352  if (!MArch) {
353    emitError(ErrMsg);
354    return false;
355  }
356
357  // Construct LTOModule, hand over ownership of module and target. Use MAttr as
358  // the default set of features.
359  SubtargetFeatures Features(MAttr);
360  Features.getDefaultSubtargetFeatures(Triple);
361  FeatureStr = Features.getString();
362  // Set a default CPU for Darwin triples.
363  if (MCpu.empty() && Triple.isOSDarwin()) {
364    if (Triple.getArch() == llvm::Triple::x86_64)
365      MCpu = "core2";
366    else if (Triple.getArch() == llvm::Triple::x86)
367      MCpu = "yonah";
368    else if (Triple.getArch() == llvm::Triple::aarch64 ||
369             Triple.getArch() == llvm::Triple::aarch64_32)
370      MCpu = "cyclone";
371  }
372
373  TargetMach = createTargetMachine();
374  return true;
375}
376
377std::unique_ptr<TargetMachine> LTOCodeGenerator::createTargetMachine() {
378  return std::unique_ptr<TargetMachine>(MArch->createTargetMachine(
379      TripleStr, MCpu, FeatureStr, Options, RelocModel, None, CGOptLevel));
380}
381
382// If a linkonce global is present in the MustPreserveSymbols, we need to make
383// sure we honor this. To force the compiler to not drop it, we add it to the
384// "llvm.compiler.used" global.
385void LTOCodeGenerator::preserveDiscardableGVs(
386    Module &TheModule,
387    llvm::function_ref<bool(const GlobalValue &)> mustPreserveGV) {
388  std::vector<GlobalValue *> Used;
389  auto mayPreserveGlobal = [&](GlobalValue &GV) {
390    if (!GV.isDiscardableIfUnused() || GV.isDeclaration() ||
391        !mustPreserveGV(GV))
392      return;
393    if (GV.hasAvailableExternallyLinkage())
394      return emitWarning(
395          (Twine("Linker asked to preserve available_externally global: '") +
396           GV.getName() + "'").str());
397    if (GV.hasInternalLinkage())
398      return emitWarning((Twine("Linker asked to preserve internal global: '") +
399                   GV.getName() + "'").str());
400    Used.push_back(&GV);
401  };
402  for (auto &GV : TheModule)
403    mayPreserveGlobal(GV);
404  for (auto &GV : TheModule.globals())
405    mayPreserveGlobal(GV);
406  for (auto &GV : TheModule.aliases())
407    mayPreserveGlobal(GV);
408
409  if (Used.empty())
410    return;
411
412  appendToCompilerUsed(TheModule, Used);
413}
414
415void LTOCodeGenerator::applyScopeRestrictions() {
416  if (ScopeRestrictionsDone)
417    return;
418
419  // Declare a callback for the internalize pass that will ask for every
420  // candidate GlobalValue if it can be internalized or not.
421  Mangler Mang;
422  SmallString<64> MangledName;
423  auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
424    // Unnamed globals can't be mangled, but they can't be preserved either.
425    if (!GV.hasName())
426      return false;
427
428    // Need to mangle the GV as the "MustPreserveSymbols" StringSet is filled
429    // with the linker supplied name, which on Darwin includes a leading
430    // underscore.
431    MangledName.clear();
432    MangledName.reserve(GV.getName().size() + 1);
433    Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
434    return MustPreserveSymbols.count(MangledName);
435  };
436
437  // Preserve linkonce value on linker request
438  preserveDiscardableGVs(*MergedModule, mustPreserveGV);
439
440  if (!ShouldInternalize)
441    return;
442
443  if (ShouldRestoreGlobalsLinkage) {
444    // Record the linkage type of non-local symbols so they can be restored
445    // prior
446    // to module splitting.
447    auto RecordLinkage = [&](const GlobalValue &GV) {
448      if (!GV.hasAvailableExternallyLinkage() && !GV.hasLocalLinkage() &&
449          GV.hasName())
450        ExternalSymbols.insert(std::make_pair(GV.getName(), GV.getLinkage()));
451    };
452    for (auto &GV : *MergedModule)
453      RecordLinkage(GV);
454    for (auto &GV : MergedModule->globals())
455      RecordLinkage(GV);
456    for (auto &GV : MergedModule->aliases())
457      RecordLinkage(GV);
458  }
459
460  // Update the llvm.compiler_used globals to force preserving libcalls and
461  // symbols referenced from asm
462  updateCompilerUsed(*MergedModule, *TargetMach, AsmUndefinedRefs);
463
464  internalizeModule(*MergedModule, mustPreserveGV);
465
466  MergedModule->addModuleFlag(Module::Error, "LTOPostLink", 1);
467
468  ScopeRestrictionsDone = true;
469}
470
471/// Restore original linkage for symbols that may have been internalized
472void LTOCodeGenerator::restoreLinkageForExternals() {
473  if (!ShouldInternalize || !ShouldRestoreGlobalsLinkage)
474    return;
475
476  assert(ScopeRestrictionsDone &&
477         "Cannot externalize without internalization!");
478
479  if (ExternalSymbols.empty())
480    return;
481
482  auto externalize = [this](GlobalValue &GV) {
483    if (!GV.hasLocalLinkage() || !GV.hasName())
484      return;
485
486    auto I = ExternalSymbols.find(GV.getName());
487    if (I == ExternalSymbols.end())
488      return;
489
490    GV.setLinkage(I->second);
491  };
492
493  llvm::for_each(MergedModule->functions(), externalize);
494  llvm::for_each(MergedModule->globals(), externalize);
495  llvm::for_each(MergedModule->aliases(), externalize);
496}
497
498void LTOCodeGenerator::verifyMergedModuleOnce() {
499  // Only run on the first call.
500  if (HasVerifiedInput)
501    return;
502  HasVerifiedInput = true;
503
504  bool BrokenDebugInfo = false;
505  if (verifyModule(*MergedModule, &dbgs(), &BrokenDebugInfo))
506    report_fatal_error("Broken module found, compilation aborted!");
507  if (BrokenDebugInfo) {
508    emitWarning("Invalid debug info found, debug info will be stripped");
509    StripDebugInfo(*MergedModule);
510  }
511}
512
513void LTOCodeGenerator::finishOptimizationRemarks() {
514  if (DiagnosticOutputFile) {
515    DiagnosticOutputFile->keep();
516    // FIXME: LTOCodeGenerator dtor is not invoked on Darwin
517    DiagnosticOutputFile->os().flush();
518  }
519}
520
521/// Optimize merged modules using various IPO passes
522bool LTOCodeGenerator::optimize(bool DisableVerify, bool DisableInline,
523                                bool DisableGVNLoadPRE,
524                                bool DisableVectorization) {
525  if (!this->determineTarget())
526    return false;
527
528  auto DiagFileOrErr =
529      lto::setupOptimizationRemarks(Context, RemarksFilename, RemarksPasses,
530                                    RemarksFormat, RemarksWithHotness);
531  if (!DiagFileOrErr) {
532    errs() << "Error: " << toString(DiagFileOrErr.takeError()) << "\n";
533    report_fatal_error("Can't get an output file for the remarks");
534  }
535  DiagnosticOutputFile = std::move(*DiagFileOrErr);
536
537  // Setup output file to emit statistics.
538  auto StatsFileOrErr = lto::setupStatsFile(LTOStatsFile);
539  if (!StatsFileOrErr) {
540    errs() << "Error: " << toString(StatsFileOrErr.takeError()) << "\n";
541    report_fatal_error("Can't get an output file for the statistics");
542  }
543  StatsFile = std::move(StatsFileOrErr.get());
544
545  // We always run the verifier once on the merged module, the `DisableVerify`
546  // parameter only applies to subsequent verify.
547  verifyMergedModuleOnce();
548
549  // Mark which symbols can not be internalized
550  this->applyScopeRestrictions();
551
552  // Instantiate the pass manager to organize the passes.
553  legacy::PassManager passes;
554
555  // Add an appropriate DataLayout instance for this module...
556  MergedModule->setDataLayout(TargetMach->createDataLayout());
557
558  passes.add(
559      createTargetTransformInfoWrapperPass(TargetMach->getTargetIRAnalysis()));
560
561  Triple TargetTriple(TargetMach->getTargetTriple());
562  PassManagerBuilder PMB;
563  PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
564  PMB.LoopVectorize = !DisableVectorization;
565  PMB.SLPVectorize = !DisableVectorization;
566  if (!DisableInline)
567    PMB.Inliner = createFunctionInliningPass();
568  PMB.LibraryInfo = new TargetLibraryInfoImpl(TargetTriple);
569  if (Freestanding)
570    PMB.LibraryInfo->disableAllFunctions();
571  PMB.OptLevel = OptLevel;
572  PMB.VerifyInput = !DisableVerify;
573  PMB.VerifyOutput = !DisableVerify;
574
575  PMB.populateLTOPassManager(passes);
576
577  // Run our queue of passes all at once now, efficiently.
578  passes.run(*MergedModule);
579
580  return true;
581}
582
583bool LTOCodeGenerator::compileOptimized(ArrayRef<raw_pwrite_stream *> Out) {
584  if (!this->determineTarget())
585    return false;
586
587  // We always run the verifier once on the merged module.  If it has already
588  // been called in optimize(), this call will return early.
589  verifyMergedModuleOnce();
590
591  legacy::PassManager preCodeGenPasses;
592
593  // If the bitcode files contain ARC code and were compiled with optimization,
594  // the ObjCARCContractPass must be run, so do it unconditionally here.
595  preCodeGenPasses.add(createObjCARCContractPass());
596  preCodeGenPasses.run(*MergedModule);
597
598  // Re-externalize globals that may have been internalized to increase scope
599  // for splitting
600  restoreLinkageForExternals();
601
602  // Do code generation. We need to preserve the module in case the client calls
603  // writeMergedModules() after compilation, but we only need to allow this at
604  // parallelism level 1. This is achieved by having splitCodeGen return the
605  // original module at parallelism level 1 which we then assign back to
606  // MergedModule.
607  MergedModule = splitCodeGen(std::move(MergedModule), Out, {},
608                              [&]() { return createTargetMachine(); }, FileType,
609                              ShouldRestoreGlobalsLinkage);
610
611  // If statistics were requested, save them to the specified file or
612  // print them out after codegen.
613  if (StatsFile)
614    PrintStatisticsJSON(StatsFile->os());
615  else if (AreStatisticsEnabled())
616    PrintStatistics();
617
618  reportAndResetTimings();
619
620  finishOptimizationRemarks();
621
622  return true;
623}
624
625void LTOCodeGenerator::setCodeGenDebugOptions(ArrayRef<const char *> Options) {
626  for (StringRef Option : Options)
627    CodegenOptions.push_back(Option);
628}
629
630void LTOCodeGenerator::parseCodeGenDebugOptions() {
631  // if options were requested, set them
632  if (!CodegenOptions.empty()) {
633    // ParseCommandLineOptions() expects argv[0] to be program name.
634    std::vector<const char *> CodegenArgv(1, "libLLVMLTO");
635    for (std::string &Arg : CodegenOptions)
636      CodegenArgv.push_back(Arg.c_str());
637    cl::ParseCommandLineOptions(CodegenArgv.size(), CodegenArgv.data());
638  }
639}
640
641
642void LTOCodeGenerator::DiagnosticHandler(const DiagnosticInfo &DI) {
643  // Map the LLVM internal diagnostic severity to the LTO diagnostic severity.
644  lto_codegen_diagnostic_severity_t Severity;
645  switch (DI.getSeverity()) {
646  case DS_Error:
647    Severity = LTO_DS_ERROR;
648    break;
649  case DS_Warning:
650    Severity = LTO_DS_WARNING;
651    break;
652  case DS_Remark:
653    Severity = LTO_DS_REMARK;
654    break;
655  case DS_Note:
656    Severity = LTO_DS_NOTE;
657    break;
658  }
659  // Create the string that will be reported to the external diagnostic handler.
660  std::string MsgStorage;
661  raw_string_ostream Stream(MsgStorage);
662  DiagnosticPrinterRawOStream DP(Stream);
663  DI.print(DP);
664  Stream.flush();
665
666  // If this method has been called it means someone has set up an external
667  // diagnostic handler. Assert on that.
668  assert(DiagHandler && "Invalid diagnostic handler");
669  (*DiagHandler)(Severity, MsgStorage.c_str(), DiagContext);
670}
671
672namespace {
673struct LTODiagnosticHandler : public DiagnosticHandler {
674  LTOCodeGenerator *CodeGenerator;
675  LTODiagnosticHandler(LTOCodeGenerator *CodeGenPtr)
676      : CodeGenerator(CodeGenPtr) {}
677  bool handleDiagnostics(const DiagnosticInfo &DI) override {
678    CodeGenerator->DiagnosticHandler(DI);
679    return true;
680  }
681};
682}
683
684void
685LTOCodeGenerator::setDiagnosticHandler(lto_diagnostic_handler_t DiagHandler,
686                                       void *Ctxt) {
687  this->DiagHandler = DiagHandler;
688  this->DiagContext = Ctxt;
689  if (!DiagHandler)
690    return Context.setDiagnosticHandler(nullptr);
691  // Register the LTOCodeGenerator stub in the LLVMContext to forward the
692  // diagnostic to the external DiagHandler.
693  Context.setDiagnosticHandler(std::make_unique<LTODiagnosticHandler>(this),
694                               true);
695}
696
697namespace {
698class LTODiagnosticInfo : public DiagnosticInfo {
699  const Twine &Msg;
700public:
701  LTODiagnosticInfo(const Twine &DiagMsg, DiagnosticSeverity Severity=DS_Error)
702      : DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
703  void print(DiagnosticPrinter &DP) const override { DP << Msg; }
704};
705}
706
707void LTOCodeGenerator::emitError(const std::string &ErrMsg) {
708  if (DiagHandler)
709    (*DiagHandler)(LTO_DS_ERROR, ErrMsg.c_str(), DiagContext);
710  else
711    Context.diagnose(LTODiagnosticInfo(ErrMsg));
712}
713
714void LTOCodeGenerator::emitWarning(const std::string &ErrMsg) {
715  if (DiagHandler)
716    (*DiagHandler)(LTO_DS_WARNING, ErrMsg.c_str(), DiagContext);
717  else
718    Context.diagnose(LTODiagnosticInfo(ErrMsg, DS_Warning));
719}
720