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      1 //===-- DWARFContext.cpp --------------------------------------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "DWARFContext.h"
     11 #include "llvm/ADT/SmallString.h"
     12 #include "llvm/Support/Dwarf.h"
     13 #include "llvm/Support/Format.h"
     14 #include "llvm/Support/Path.h"
     15 #include "llvm/Support/raw_ostream.h"
     16 #include <algorithm>
     17 using namespace llvm;
     18 using namespace dwarf;
     19 
     20 typedef DWARFDebugLine::LineTable DWARFLineTable;
     21 
     22 void DWARFContext::dump(raw_ostream &OS, DIDumpType DumpType) {
     23   if (DumpType == DIDT_All || DumpType == DIDT_Abbrev) {
     24     OS << ".debug_abbrev contents:\n";
     25     getDebugAbbrev()->dump(OS);
     26   }
     27 
     28   if (DumpType == DIDT_All || DumpType == DIDT_Info) {
     29     OS << "\n.debug_info contents:\n";
     30     for (unsigned i = 0, e = getNumCompileUnits(); i != e; ++i)
     31       getCompileUnitAtIndex(i)->dump(OS);
     32   }
     33 
     34   if (DumpType == DIDT_All || DumpType == DIDT_Frames) {
     35     OS << "\n.debug_frame contents:\n";
     36     getDebugFrame()->dump(OS);
     37   }
     38 
     39   uint32_t offset = 0;
     40   if (DumpType == DIDT_All || DumpType == DIDT_Aranges) {
     41     OS << "\n.debug_aranges contents:\n";
     42     DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
     43     DWARFDebugArangeSet set;
     44     while (set.extract(arangesData, &offset))
     45       set.dump(OS);
     46   }
     47 
     48   uint8_t savedAddressByteSize = 0;
     49   if (DumpType == DIDT_All || DumpType == DIDT_Line) {
     50     OS << "\n.debug_line contents:\n";
     51     for (unsigned i = 0, e = getNumCompileUnits(); i != e; ++i) {
     52       DWARFCompileUnit *cu = getCompileUnitAtIndex(i);
     53       savedAddressByteSize = cu->getAddressByteSize();
     54       unsigned stmtOffset =
     55         cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_stmt_list,
     56                                                              -1U);
     57       if (stmtOffset != -1U) {
     58         DataExtractor lineData(getLineSection(), isLittleEndian(),
     59                                savedAddressByteSize);
     60         DWARFDebugLine::DumpingState state(OS);
     61         DWARFDebugLine::parseStatementTable(lineData, &lineRelocMap(), &stmtOffset, state);
     62       }
     63     }
     64   }
     65 
     66   if (DumpType == DIDT_All || DumpType == DIDT_Str) {
     67     OS << "\n.debug_str contents:\n";
     68     DataExtractor strData(getStringSection(), isLittleEndian(), 0);
     69     offset = 0;
     70     uint32_t strOffset = 0;
     71     while (const char *s = strData.getCStr(&offset)) {
     72       OS << format("0x%8.8x: \"%s\"\n", strOffset, s);
     73       strOffset = offset;
     74     }
     75   }
     76 
     77   if (DumpType == DIDT_All || DumpType == DIDT_Ranges) {
     78     OS << "\n.debug_ranges contents:\n";
     79     // In fact, different compile units may have different address byte
     80     // sizes, but for simplicity we just use the address byte size of the last
     81     // compile unit (there is no easy and fast way to associate address range
     82     // list and the compile unit it describes).
     83     DataExtractor rangesData(getRangeSection(), isLittleEndian(),
     84                              savedAddressByteSize);
     85     offset = 0;
     86     DWARFDebugRangeList rangeList;
     87     while (rangeList.extract(rangesData, &offset))
     88       rangeList.dump(OS);
     89   }
     90 
     91   if (DumpType == DIDT_All || DumpType == DIDT_Pubnames) {
     92     OS << "\n.debug_pubnames contents:\n";
     93     DataExtractor pubNames(getPubNamesSection(), isLittleEndian(), 0);
     94     offset = 0;
     95     OS << "Length:                " << pubNames.getU32(&offset) << "\n";
     96     OS << "Version:               " << pubNames.getU16(&offset) << "\n";
     97     OS << "Offset in .debug_info: " << pubNames.getU32(&offset) << "\n";
     98     OS << "Size:                  " << pubNames.getU32(&offset) << "\n";
     99     OS << "\n  Offset    Name\n";
    100     while (offset < getPubNamesSection().size()) {
    101       uint32_t n = pubNames.getU32(&offset);
    102       if (n == 0)
    103         break;
    104       OS << format("%8x    ", n);
    105       OS << pubNames.getCStr(&offset) << "\n";
    106     }
    107   }
    108 
    109   if (DumpType == DIDT_All || DumpType == DIDT_AbbrevDwo) {
    110     OS << "\n.debug_abbrev.dwo contents:\n";
    111     getDebugAbbrevDWO()->dump(OS);
    112   }
    113 
    114   if (DumpType == DIDT_All || DumpType == DIDT_InfoDwo) {
    115     OS << "\n.debug_info.dwo contents:\n";
    116     for (unsigned i = 0, e = getNumDWOCompileUnits(); i != e; ++i)
    117       getDWOCompileUnitAtIndex(i)->dump(OS);
    118   }
    119 
    120   if (DumpType == DIDT_All || DumpType == DIDT_StrDwo) {
    121     OS << "\n.debug_str.dwo contents:\n";
    122     DataExtractor strDWOData(getStringDWOSection(), isLittleEndian(), 0);
    123     offset = 0;
    124     uint32_t strDWOOffset = 0;
    125     while (const char *s = strDWOData.getCStr(&offset)) {
    126       OS << format("0x%8.8x: \"%s\"\n", strDWOOffset, s);
    127       strDWOOffset = offset;
    128     }
    129   }
    130 
    131   if (DumpType == DIDT_All || DumpType == DIDT_StrOffsetsDwo) {
    132     OS << "\n.debug_str_offsets.dwo contents:\n";
    133     DataExtractor strOffsetExt(getStringOffsetDWOSection(), isLittleEndian(), 0);
    134     offset = 0;
    135     while (offset < getStringOffsetDWOSection().size()) {
    136       OS << format("0x%8.8x: ", offset);
    137       OS << format("%8.8x\n", strOffsetExt.getU32(&offset));
    138     }
    139   }
    140 }
    141 
    142 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrev() {
    143   if (Abbrev)
    144     return Abbrev.get();
    145 
    146   DataExtractor abbrData(getAbbrevSection(), isLittleEndian(), 0);
    147 
    148   Abbrev.reset(new DWARFDebugAbbrev());
    149   Abbrev->parse(abbrData);
    150   return Abbrev.get();
    151 }
    152 
    153 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrevDWO() {
    154   if (AbbrevDWO)
    155     return AbbrevDWO.get();
    156 
    157   DataExtractor abbrData(getAbbrevDWOSection(), isLittleEndian(), 0);
    158   AbbrevDWO.reset(new DWARFDebugAbbrev());
    159   AbbrevDWO->parse(abbrData);
    160   return AbbrevDWO.get();
    161 }
    162 
    163 const DWARFDebugAranges *DWARFContext::getDebugAranges() {
    164   if (Aranges)
    165     return Aranges.get();
    166 
    167   DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
    168 
    169   Aranges.reset(new DWARFDebugAranges());
    170   Aranges->extract(arangesData);
    171   // Generate aranges from DIEs: even if .debug_aranges section is present,
    172   // it may describe only a small subset of compilation units, so we need to
    173   // manually build aranges for the rest of them.
    174   Aranges->generate(this);
    175   return Aranges.get();
    176 }
    177 
    178 const DWARFDebugFrame *DWARFContext::getDebugFrame() {
    179   if (DebugFrame)
    180     return DebugFrame.get();
    181 
    182   // There's a "bug" in the DWARFv3 standard with respect to the target address
    183   // size within debug frame sections. While DWARF is supposed to be independent
    184   // of its container, FDEs have fields with size being "target address size",
    185   // which isn't specified in DWARF in general. It's only specified for CUs, but
    186   // .eh_frame can appear without a .debug_info section. Follow the example of
    187   // other tools (libdwarf) and extract this from the container (ObjectFile
    188   // provides this information). This problem is fixed in DWARFv4
    189   // See this dwarf-discuss discussion for more details:
    190   // http://lists.dwarfstd.org/htdig.cgi/dwarf-discuss-dwarfstd.org/2011-December/001173.html
    191   DataExtractor debugFrameData(getDebugFrameSection(), isLittleEndian(),
    192                                getAddressSize());
    193   DebugFrame.reset(new DWARFDebugFrame());
    194   DebugFrame->parse(debugFrameData);
    195   return DebugFrame.get();
    196 }
    197 
    198 const DWARFLineTable *
    199 DWARFContext::getLineTableForCompileUnit(DWARFCompileUnit *cu) {
    200   if (!Line)
    201     Line.reset(new DWARFDebugLine(&lineRelocMap()));
    202 
    203   unsigned stmtOffset =
    204     cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_stmt_list,
    205                                                          -1U);
    206   if (stmtOffset == -1U)
    207     return 0; // No line table for this compile unit.
    208 
    209   // See if the line table is cached.
    210   if (const DWARFLineTable *lt = Line->getLineTable(stmtOffset))
    211     return lt;
    212 
    213   // We have to parse it first.
    214   DataExtractor lineData(getLineSection(), isLittleEndian(),
    215                          cu->getAddressByteSize());
    216   return Line->getOrParseLineTable(lineData, stmtOffset);
    217 }
    218 
    219 void DWARFContext::parseCompileUnits() {
    220   uint32_t offset = 0;
    221   const DataExtractor &DIData = DataExtractor(getInfoSection(),
    222                                               isLittleEndian(), 0);
    223   while (DIData.isValidOffset(offset)) {
    224     CUs.push_back(DWARFCompileUnit(getDebugAbbrev(), getInfoSection(),
    225                                    getAbbrevSection(), getRangeSection(),
    226                                    getStringSection(), StringRef(),
    227                                    getAddrSection(),
    228                                    &infoRelocMap(),
    229                                    isLittleEndian()));
    230     if (!CUs.back().extract(DIData, &offset)) {
    231       CUs.pop_back();
    232       break;
    233     }
    234 
    235     offset = CUs.back().getNextCompileUnitOffset();
    236   }
    237 }
    238 
    239 void DWARFContext::parseDWOCompileUnits() {
    240   uint32_t offset = 0;
    241   const DataExtractor &DIData = DataExtractor(getInfoDWOSection(),
    242                                               isLittleEndian(), 0);
    243   while (DIData.isValidOffset(offset)) {
    244     DWOCUs.push_back(DWARFCompileUnit(getDebugAbbrevDWO(), getInfoDWOSection(),
    245                                       getAbbrevDWOSection(),
    246                                       getRangeDWOSection(),
    247                                       getStringDWOSection(),
    248                                       getStringOffsetDWOSection(),
    249                                       getAddrSection(),
    250                                       &infoDWORelocMap(),
    251                                       isLittleEndian()));
    252     if (!DWOCUs.back().extract(DIData, &offset)) {
    253       DWOCUs.pop_back();
    254       break;
    255     }
    256 
    257     offset = DWOCUs.back().getNextCompileUnitOffset();
    258   }
    259 }
    260 
    261 namespace {
    262   struct OffsetComparator {
    263     bool operator()(const DWARFCompileUnit &LHS,
    264                     const DWARFCompileUnit &RHS) const {
    265       return LHS.getOffset() < RHS.getOffset();
    266     }
    267     bool operator()(const DWARFCompileUnit &LHS, uint32_t RHS) const {
    268       return LHS.getOffset() < RHS;
    269     }
    270     bool operator()(uint32_t LHS, const DWARFCompileUnit &RHS) const {
    271       return LHS < RHS.getOffset();
    272     }
    273   };
    274 }
    275 
    276 DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t Offset) {
    277   if (CUs.empty())
    278     parseCompileUnits();
    279 
    280   DWARFCompileUnit *CU = std::lower_bound(CUs.begin(), CUs.end(), Offset,
    281                                           OffsetComparator());
    282   if (CU != CUs.end())
    283     return &*CU;
    284   return 0;
    285 }
    286 
    287 DWARFCompileUnit *DWARFContext::getCompileUnitForAddress(uint64_t Address) {
    288   // First, get the offset of the compile unit.
    289   uint32_t CUOffset = getDebugAranges()->findAddress(Address);
    290   // Retrieve the compile unit.
    291   return getCompileUnitForOffset(CUOffset);
    292 }
    293 
    294 static bool getFileNameForCompileUnit(DWARFCompileUnit *CU,
    295                                       const DWARFLineTable *LineTable,
    296                                       uint64_t FileIndex,
    297                                       bool NeedsAbsoluteFilePath,
    298                                       std::string &FileName) {
    299   if (CU == 0 ||
    300       LineTable == 0 ||
    301       !LineTable->getFileNameByIndex(FileIndex, NeedsAbsoluteFilePath,
    302                                      FileName))
    303     return false;
    304   if (NeedsAbsoluteFilePath && sys::path::is_relative(FileName)) {
    305     // We may still need to append compilation directory of compile unit.
    306     SmallString<16> AbsolutePath;
    307     if (const char *CompilationDir = CU->getCompilationDir()) {
    308       sys::path::append(AbsolutePath, CompilationDir);
    309     }
    310     sys::path::append(AbsolutePath, FileName);
    311     FileName = AbsolutePath.str();
    312   }
    313   return true;
    314 }
    315 
    316 static bool getFileLineInfoForCompileUnit(DWARFCompileUnit *CU,
    317                                           const DWARFLineTable *LineTable,
    318                                           uint64_t Address,
    319                                           bool NeedsAbsoluteFilePath,
    320                                           std::string &FileName,
    321                                           uint32_t &Line, uint32_t &Column) {
    322   if (CU == 0 || LineTable == 0)
    323     return false;
    324   // Get the index of row we're looking for in the line table.
    325   uint32_t RowIndex = LineTable->lookupAddress(Address);
    326   if (RowIndex == -1U)
    327     return false;
    328   // Take file number and line/column from the row.
    329   const DWARFDebugLine::Row &Row = LineTable->Rows[RowIndex];
    330   if (!getFileNameForCompileUnit(CU, LineTable, Row.File,
    331                                  NeedsAbsoluteFilePath, FileName))
    332     return false;
    333   Line = Row.Line;
    334   Column = Row.Column;
    335   return true;
    336 }
    337 
    338 DILineInfo DWARFContext::getLineInfoForAddress(uint64_t Address,
    339     DILineInfoSpecifier Specifier) {
    340   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
    341   if (!CU)
    342     return DILineInfo();
    343   std::string FileName = "<invalid>";
    344   std::string FunctionName = "<invalid>";
    345   uint32_t Line = 0;
    346   uint32_t Column = 0;
    347   if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
    348     // The address may correspond to instruction in some inlined function,
    349     // so we have to build the chain of inlined functions and take the
    350     // name of the topmost function in it.
    351     const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
    352         CU->getInlinedChainForAddress(Address);
    353     if (InlinedChain.size() > 0) {
    354       const DWARFDebugInfoEntryMinimal &TopFunctionDIE = InlinedChain[0];
    355       if (const char *Name = TopFunctionDIE.getSubroutineName(CU))
    356         FunctionName = Name;
    357     }
    358   }
    359   if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
    360     const DWARFLineTable *LineTable = getLineTableForCompileUnit(CU);
    361     const bool NeedsAbsoluteFilePath =
    362         Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
    363     getFileLineInfoForCompileUnit(CU, LineTable, Address,
    364                                   NeedsAbsoluteFilePath,
    365                                   FileName, Line, Column);
    366   }
    367   return DILineInfo(StringRef(FileName), StringRef(FunctionName),
    368                     Line, Column);
    369 }
    370 
    371 DILineInfoTable DWARFContext::getLineInfoForAddressRange(uint64_t Address,
    372     uint64_t Size,
    373     DILineInfoSpecifier Specifier) {
    374   DILineInfoTable  Lines;
    375   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
    376   if (!CU)
    377     return Lines;
    378 
    379   std::string FunctionName = "<invalid>";
    380   if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
    381     // The address may correspond to instruction in some inlined function,
    382     // so we have to build the chain of inlined functions and take the
    383     // name of the topmost function in it.
    384     const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
    385         CU->getInlinedChainForAddress(Address);
    386     if (InlinedChain.size() > 0) {
    387       const DWARFDebugInfoEntryMinimal &TopFunctionDIE = InlinedChain[0];
    388       if (const char *Name = TopFunctionDIE.getSubroutineName(CU))
    389         FunctionName = Name;
    390     }
    391   }
    392 
    393   StringRef  FuncNameRef = StringRef(FunctionName);
    394 
    395   // If the Specifier says we don't need FileLineInfo, just
    396   // return the top-most function at the starting address.
    397   if (!Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
    398     Lines.push_back(std::make_pair(Address,
    399                                    DILineInfo(StringRef("<invalid>"),
    400                                               FuncNameRef, 0, 0)));
    401     return Lines;
    402   }
    403 
    404   const DWARFLineTable *LineTable = getLineTableForCompileUnit(CU);
    405   const bool NeedsAbsoluteFilePath =
    406       Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
    407 
    408   // Get the index of row we're looking for in the line table.
    409   std::vector<uint32_t> RowVector;
    410   if (!LineTable->lookupAddressRange(Address, Size, RowVector))
    411     return Lines;
    412 
    413   uint32_t NumRows = RowVector.size();
    414   for (uint32_t i = 0; i < NumRows; ++i) {
    415     uint32_t RowIndex = RowVector[i];
    416     // Take file number and line/column from the row.
    417     const DWARFDebugLine::Row &Row = LineTable->Rows[RowIndex];
    418     std::string FileName = "<invalid>";
    419     getFileNameForCompileUnit(CU, LineTable, Row.File,
    420                               NeedsAbsoluteFilePath, FileName);
    421     Lines.push_back(std::make_pair(Row.Address,
    422                                    DILineInfo(StringRef(FileName),
    423                                          FuncNameRef, Row.Line, Row.Column)));
    424   }
    425 
    426   return Lines;
    427 }
    428 
    429 DIInliningInfo DWARFContext::getInliningInfoForAddress(uint64_t Address,
    430     DILineInfoSpecifier Specifier) {
    431   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
    432   if (!CU)
    433     return DIInliningInfo();
    434 
    435   const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
    436       CU->getInlinedChainForAddress(Address);
    437   if (InlinedChain.size() == 0)
    438     return DIInliningInfo();
    439 
    440   DIInliningInfo InliningInfo;
    441   uint32_t CallFile = 0, CallLine = 0, CallColumn = 0;
    442   const DWARFLineTable *LineTable = 0;
    443   for (uint32_t i = 0, n = InlinedChain.size(); i != n; i++) {
    444     const DWARFDebugInfoEntryMinimal &FunctionDIE = InlinedChain[i];
    445     std::string FileName = "<invalid>";
    446     std::string FunctionName = "<invalid>";
    447     uint32_t Line = 0;
    448     uint32_t Column = 0;
    449     // Get function name if necessary.
    450     if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
    451       if (const char *Name = FunctionDIE.getSubroutineName(CU))
    452         FunctionName = Name;
    453     }
    454     if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
    455       const bool NeedsAbsoluteFilePath =
    456           Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
    457       if (i == 0) {
    458         // For the topmost frame, initialize the line table of this
    459         // compile unit and fetch file/line info from it.
    460         LineTable = getLineTableForCompileUnit(CU);
    461         // For the topmost routine, get file/line info from line table.
    462         getFileLineInfoForCompileUnit(CU, LineTable, Address,
    463                                       NeedsAbsoluteFilePath,
    464                                       FileName, Line, Column);
    465       } else {
    466         // Otherwise, use call file, call line and call column from
    467         // previous DIE in inlined chain.
    468         getFileNameForCompileUnit(CU, LineTable, CallFile,
    469                                   NeedsAbsoluteFilePath, FileName);
    470         Line = CallLine;
    471         Column = CallColumn;
    472       }
    473       // Get call file/line/column of a current DIE.
    474       if (i + 1 < n) {
    475         FunctionDIE.getCallerFrame(CU, CallFile, CallLine, CallColumn);
    476       }
    477     }
    478     DILineInfo Frame(StringRef(FileName), StringRef(FunctionName),
    479                      Line, Column);
    480     InliningInfo.addFrame(Frame);
    481   }
    482   return InliningInfo;
    483 }
    484 
    485 DWARFContextInMemory::DWARFContextInMemory(object::ObjectFile *Obj) :
    486   IsLittleEndian(Obj->isLittleEndian()),
    487   AddressSize(Obj->getBytesInAddress()) {
    488   error_code ec;
    489   for (object::section_iterator i = Obj->begin_sections(),
    490          e = Obj->end_sections();
    491        i != e; i.increment(ec)) {
    492     StringRef name;
    493     i->getName(name);
    494     StringRef data;
    495     i->getContents(data);
    496 
    497     name = name.substr(name.find_first_not_of("._")); // Skip . and _ prefixes.
    498     if (name == "debug_info")
    499       InfoSection = data;
    500     else if (name == "debug_abbrev")
    501       AbbrevSection = data;
    502     else if (name == "debug_line")
    503       LineSection = data;
    504     else if (name == "debug_aranges")
    505       ARangeSection = data;
    506     else if (name == "debug_frame")
    507       DebugFrameSection = data;
    508     else if (name == "debug_str")
    509       StringSection = data;
    510     else if (name == "debug_ranges") {
    511       // FIXME: Use the other dwo range section when we emit it.
    512       RangeDWOSection = data;
    513       RangeSection = data;
    514     }
    515     else if (name == "debug_pubnames")
    516       PubNamesSection = data;
    517     else if (name == "debug_info.dwo")
    518       InfoDWOSection = data;
    519     else if (name == "debug_abbrev.dwo")
    520       AbbrevDWOSection = data;
    521     else if (name == "debug_str.dwo")
    522       StringDWOSection = data;
    523     else if (name == "debug_str_offsets.dwo")
    524       StringOffsetDWOSection = data;
    525     else if (name == "debug_addr")
    526       AddrSection = data;
    527     // Any more debug info sections go here.
    528     else
    529       continue;
    530 
    531     // TODO: Add support for relocations in other sections as needed.
    532     // Record relocations for the debug_info and debug_line sections.
    533     RelocAddrMap *Map;
    534     if (name == "debug_info")
    535       Map = &InfoRelocMap;
    536     else if (name == "debug_info.dwo")
    537       Map = &InfoDWORelocMap;
    538     else if (name == "debug_line")
    539       Map = &LineRelocMap;
    540     else
    541       continue;
    542 
    543     if (i->begin_relocations() != i->end_relocations()) {
    544       uint64_t SectionSize;
    545       i->getSize(SectionSize);
    546       for (object::relocation_iterator reloc_i = i->begin_relocations(),
    547              reloc_e = i->end_relocations();
    548            reloc_i != reloc_e; reloc_i.increment(ec)) {
    549         uint64_t Address;
    550         reloc_i->getAddress(Address);
    551         uint64_t Type;
    552         reloc_i->getType(Type);
    553         uint64_t SymAddr = 0;
    554         // ELF relocations may need the symbol address
    555         if (Obj->isELF()) {
    556           object::SymbolRef Sym;
    557           reloc_i->getSymbol(Sym);
    558           Sym.getAddress(SymAddr);
    559         }
    560 
    561         object::RelocVisitor V(Obj->getFileFormatName());
    562         // The section address is always 0 for debug sections.
    563         object::RelocToApply R(V.visit(Type, *reloc_i, 0, SymAddr));
    564         if (V.error()) {
    565           SmallString<32> Name;
    566           error_code ec(reloc_i->getTypeName(Name));
    567           if (ec) {
    568             errs() << "Aaaaaa! Nameless relocation! Aaaaaa!\n";
    569           }
    570           errs() << "error: failed to compute relocation: "
    571                  << Name << "\n";
    572           continue;
    573         }
    574 
    575         if (Address + R.Width > SectionSize) {
    576           errs() << "error: " << R.Width << "-byte relocation starting "
    577                  << Address << " bytes into section " << name << " which is "
    578                  << SectionSize << " bytes long.\n";
    579           continue;
    580         }
    581         if (R.Width > 8) {
    582           errs() << "error: can't handle a relocation of more than 8 bytes at "
    583                     "a time.\n";
    584           continue;
    585         }
    586         DEBUG(dbgs() << "Writing " << format("%p", R.Value)
    587                      << " at " << format("%p", Address)
    588                      << " with width " << format("%d", R.Width)
    589                      << "\n");
    590         Map->insert(std::make_pair(Address, std::make_pair(R.Width, R.Value)));
    591       }
    592     }
    593   }
    594 }
    595 
    596 void DWARFContextInMemory::anchor() { }
    597