272 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			272 lines
		
	
	
		
			10 KiB
		
	
	
	
		
			C++
		
	
	
	
//===- SymbolizableObjectFile.cpp -----------------------------------------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Implementation of SymbolizableObjectFile class.
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//
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//===----------------------------------------------------------------------===//
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#include "SymbolizableObjectFile.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/BinaryFormat/COFF.h"
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#include "llvm/DebugInfo/DWARF/DWARFContext.h"
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#include "llvm/DebugInfo/Symbolize/SymbolizableModule.h"
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#include "llvm/Object/COFF.h"
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#include "llvm/Object/ObjectFile.h"
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#include "llvm/Object/SymbolSize.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/DataExtractor.h"
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#include "llvm/Support/Error.h"
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#include <algorithm>
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#include <cstdint>
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#include <memory>
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#include <string>
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#include <system_error>
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#include <utility>
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#include <vector>
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using namespace llvm;
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using namespace object;
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using namespace symbolize;
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static DILineInfoSpecifier
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getDILineInfoSpecifier(FunctionNameKind FNKind) {
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  return DILineInfoSpecifier(
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      DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FNKind);
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}
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ErrorOr<std::unique_ptr<SymbolizableObjectFile>>
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SymbolizableObjectFile::create(object::ObjectFile *Obj,
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                               std::unique_ptr<DIContext> DICtx) {
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  std::unique_ptr<SymbolizableObjectFile> res(
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      new SymbolizableObjectFile(Obj, std::move(DICtx)));
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  std::unique_ptr<DataExtractor> OpdExtractor;
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  uint64_t OpdAddress = 0;
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  // Find the .opd (function descriptor) section if any, for big-endian
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  // PowerPC64 ELF.
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  if (Obj->getArch() == Triple::ppc64) {
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    for (section_iterator Section : Obj->sections()) {
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      StringRef Name;
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      StringRef Data;
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      if (auto EC = Section->getName(Name))
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        return EC;
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      if (Name == ".opd") {
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        if (auto EC = Section->getContents(Data))
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          return EC;
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        OpdExtractor.reset(new DataExtractor(Data, Obj->isLittleEndian(),
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                                             Obj->getBytesInAddress()));
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        OpdAddress = Section->getAddress();
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        break;
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      }
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    }
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  }
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  std::vector<std::pair<SymbolRef, uint64_t>> Symbols =
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      computeSymbolSizes(*Obj);
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  for (auto &P : Symbols)
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    res->addSymbol(P.first, P.second, OpdExtractor.get(), OpdAddress);
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  // If this is a COFF object and we didn't find any symbols, try the export
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  // table.
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  if (Symbols.empty()) {
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    if (auto *CoffObj = dyn_cast<COFFObjectFile>(Obj))
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      if (auto EC = res->addCoffExportSymbols(CoffObj))
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        return EC;
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  }
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  return std::move(res);
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}
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SymbolizableObjectFile::SymbolizableObjectFile(ObjectFile *Obj,
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                                               std::unique_ptr<DIContext> DICtx)
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    : Module(Obj), DebugInfoContext(std::move(DICtx)) {}
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namespace {
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struct OffsetNamePair {
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  uint32_t Offset;
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  StringRef Name;
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  bool operator<(const OffsetNamePair &R) const {
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    return Offset < R.Offset;
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  }
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};
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} // end anonymous namespace
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std::error_code SymbolizableObjectFile::addCoffExportSymbols(
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    const COFFObjectFile *CoffObj) {
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  // Get all export names and offsets.
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  std::vector<OffsetNamePair> ExportSyms;
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  for (const ExportDirectoryEntryRef &Ref : CoffObj->export_directories()) {
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    StringRef Name;
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    uint32_t Offset;
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    if (auto EC = Ref.getSymbolName(Name))
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      return EC;
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    if (auto EC = Ref.getExportRVA(Offset))
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      return EC;
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    ExportSyms.push_back(OffsetNamePair{Offset, Name});
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  }
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  if (ExportSyms.empty())
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    return std::error_code();
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  // Sort by ascending offset.
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  array_pod_sort(ExportSyms.begin(), ExportSyms.end());
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  // Approximate the symbol sizes by assuming they run to the next symbol.
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  // FIXME: This assumes all exports are functions.
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  uint64_t ImageBase = CoffObj->getImageBase();
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  for (auto I = ExportSyms.begin(), E = ExportSyms.end(); I != E; ++I) {
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    OffsetNamePair &Export = *I;
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    // FIXME: The last export has a one byte size now.
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    uint32_t NextOffset = I != E ? I->Offset : Export.Offset + 1;
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    uint64_t SymbolStart = ImageBase + Export.Offset;
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    uint64_t SymbolSize = NextOffset - Export.Offset;
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    SymbolDesc SD = {SymbolStart, SymbolSize};
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    Functions.insert(std::make_pair(SD, Export.Name));
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  }
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  return std::error_code();
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}
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std::error_code SymbolizableObjectFile::addSymbol(const SymbolRef &Symbol,
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                                                  uint64_t SymbolSize,
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                                                  DataExtractor *OpdExtractor,
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                                                  uint64_t OpdAddress) {
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  Expected<SymbolRef::Type> SymbolTypeOrErr = Symbol.getType();
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  if (!SymbolTypeOrErr)
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    return errorToErrorCode(SymbolTypeOrErr.takeError());
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  SymbolRef::Type SymbolType = *SymbolTypeOrErr;
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  if (SymbolType != SymbolRef::ST_Function && SymbolType != SymbolRef::ST_Data)
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    return std::error_code();
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  Expected<uint64_t> SymbolAddressOrErr = Symbol.getAddress();
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  if (!SymbolAddressOrErr)
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    return errorToErrorCode(SymbolAddressOrErr.takeError());
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  uint64_t SymbolAddress = *SymbolAddressOrErr;
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  if (OpdExtractor) {
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    // For big-endian PowerPC64 ELF, symbols in the .opd section refer to
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    // function descriptors. The first word of the descriptor is a pointer to
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    // the function's code.
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    // For the purposes of symbolization, pretend the symbol's address is that
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    // of the function's code, not the descriptor.
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    uint64_t OpdOffset = SymbolAddress - OpdAddress;
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    uint32_t OpdOffset32 = OpdOffset;
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    if (OpdOffset == OpdOffset32 &&
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        OpdExtractor->isValidOffsetForAddress(OpdOffset32))
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      SymbolAddress = OpdExtractor->getAddress(&OpdOffset32);
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  }
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  Expected<StringRef> SymbolNameOrErr = Symbol.getName();
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  if (!SymbolNameOrErr)
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    return errorToErrorCode(SymbolNameOrErr.takeError());
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  StringRef SymbolName = *SymbolNameOrErr;
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  // Mach-O symbol table names have leading underscore, skip it.
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  if (Module->isMachO() && !SymbolName.empty() && SymbolName[0] == '_')
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    SymbolName = SymbolName.drop_front();
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  // FIXME: If a function has alias, there are two entries in symbol table
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  // with same address size. Make sure we choose the correct one.
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  auto &M = SymbolType == SymbolRef::ST_Function ? Functions : Objects;
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  SymbolDesc SD = { SymbolAddress, SymbolSize };
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  M.insert(std::make_pair(SD, SymbolName));
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  return std::error_code();
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}
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// Return true if this is a 32-bit x86 PE COFF module.
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bool SymbolizableObjectFile::isWin32Module() const {
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  auto *CoffObject = dyn_cast<COFFObjectFile>(Module);
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  return CoffObject && CoffObject->getMachine() == COFF::IMAGE_FILE_MACHINE_I386;
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}
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uint64_t SymbolizableObjectFile::getModulePreferredBase() const {
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  if (auto *CoffObject = dyn_cast<COFFObjectFile>(Module))
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    return CoffObject->getImageBase();
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  return 0;
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}
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bool SymbolizableObjectFile::getNameFromSymbolTable(SymbolRef::Type Type,
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                                                    uint64_t Address,
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                                                    std::string &Name,
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                                                    uint64_t &Addr,
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                                                    uint64_t &Size) const {
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  const auto &SymbolMap = Type == SymbolRef::ST_Function ? Functions : Objects;
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  if (SymbolMap.empty())
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    return false;
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  SymbolDesc SD = { Address, Address };
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  auto SymbolIterator = SymbolMap.upper_bound(SD);
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  if (SymbolIterator == SymbolMap.begin())
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    return false;
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  --SymbolIterator;
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  if (SymbolIterator->first.Size != 0 &&
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      SymbolIterator->first.Addr + SymbolIterator->first.Size <= Address)
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    return false;
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  Name = SymbolIterator->second.str();
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  Addr = SymbolIterator->first.Addr;
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  Size = SymbolIterator->first.Size;
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  return true;
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}
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bool SymbolizableObjectFile::shouldOverrideWithSymbolTable(
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    FunctionNameKind FNKind, bool UseSymbolTable) const {
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  // When DWARF is used with -gline-tables-only / -gmlt, the symbol table gives
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  // better answers for linkage names than the DIContext. Otherwise, we are
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  // probably using PEs and PDBs, and we shouldn't do the override. PE files
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  // generally only contain the names of exported symbols.
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  return FNKind == FunctionNameKind::LinkageName && UseSymbolTable &&
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         isa<DWARFContext>(DebugInfoContext.get());
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}
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DILineInfo SymbolizableObjectFile::symbolizeCode(uint64_t ModuleOffset,
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                                                 FunctionNameKind FNKind,
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                                                 bool UseSymbolTable) const {
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  DILineInfo LineInfo;
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  if (DebugInfoContext) {
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    LineInfo = DebugInfoContext->getLineInfoForAddress(
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        ModuleOffset, getDILineInfoSpecifier(FNKind));
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  }
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  // Override function name from symbol table if necessary.
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  if (shouldOverrideWithSymbolTable(FNKind, UseSymbolTable)) {
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    std::string FunctionName;
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    uint64_t Start, Size;
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    if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
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                               FunctionName, Start, Size)) {
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      LineInfo.FunctionName = FunctionName;
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    }
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  }
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  return LineInfo;
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}
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DIInliningInfo SymbolizableObjectFile::symbolizeInlinedCode(
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    uint64_t ModuleOffset, FunctionNameKind FNKind, bool UseSymbolTable) const {
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  DIInliningInfo InlinedContext;
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  if (DebugInfoContext)
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    InlinedContext = DebugInfoContext->getInliningInfoForAddress(
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        ModuleOffset, getDILineInfoSpecifier(FNKind));
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  // Make sure there is at least one frame in context.
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  if (InlinedContext.getNumberOfFrames() == 0)
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    InlinedContext.addFrame(DILineInfo());
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  // Override the function name in lower frame with name from symbol table.
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  if (shouldOverrideWithSymbolTable(FNKind, UseSymbolTable)) {
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    std::string FunctionName;
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    uint64_t Start, Size;
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    if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
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                               FunctionName, Start, Size)) {
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      InlinedContext.getMutableFrame(InlinedContext.getNumberOfFrames() - 1)
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          ->FunctionName = FunctionName;
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    }
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  }
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  return InlinedContext;
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}
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DIGlobal SymbolizableObjectFile::symbolizeData(uint64_t ModuleOffset) const {
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  DIGlobal Res;
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  getNameFromSymbolTable(SymbolRef::ST_Data, ModuleOffset, Res.Name, Res.Start,
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                         Res.Size);
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  return Res;
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}
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