llvm/lib/DebugInfo/DWARFContext.cpp - toolchain/llvm-project - Gitiles

 //===-- DWARFContext.cpp --------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//

 #include "DWARFContext.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 using namespace llvm;
 using namespace dwarf;

 typedef DWARFDebugLine::LineTable DWARFLineTable;

 void DWARFContext::dump(raw_ostream &OS) {
   OS << ".debug_abbrev contents:\n";
   getDebugAbbrev()->dump(OS);

   OS << "\n.debug_info contents:\n";
   for (unsigned i = 0, e = getNumCompileUnits(); i != e; ++i)
     getCompileUnitAtIndex(i)->dump(OS);

   OS << "\n.debug_aranges contents:\n";
   DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
   uint32_t offset = 0;
   DWARFDebugArangeSet set;
   while (set.extract(arangesData, &offset))
     set.dump(OS);

   uint8_t savedAddressByteSize = 0;
   OS << "\n.debug_line contents:\n";
   for (unsigned i = 0, e = getNumCompileUnits(); i != e; ++i) {
     DWARFCompileUnit *cu = getCompileUnitAtIndex(i);
     savedAddressByteSize = cu->getAddressByteSize();
     unsigned stmtOffset =
       cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_stmt_list,
                                                            -1U);
     if (stmtOffset != -1U) {
       DataExtractor lineData(getLineSection(), isLittleEndian(),
                              savedAddressByteSize);
       DWARFDebugLine::DumpingState state(OS);
       DWARFDebugLine::parseStatementTable(lineData, &stmtOffset, state);
     }
   }

   OS << "\n.debug_str contents:\n";
   DataExtractor strData(getStringSection(), isLittleEndian(), 0);
   offset = 0;
   uint32_t strOffset = 0;
   while (const char *s = strData.getCStr(&offset)) {
     OS << format("0x%8.8x: \"%s\"\n", strOffset, s);
     strOffset = offset;
   }

   OS << "\n.debug_ranges contents:\n";
   // In fact, different compile units may have different address byte
   // sizes, but for simplicity we just use the address byte size of the last
   // compile unit (there is no easy and fast way to associate address range
   // list and the compile unit it describes).
   DataExtractor rangesData(getRangeSection(), isLittleEndian(),
                            savedAddressByteSize);
   offset = 0;
   DWARFDebugRangeList rangeList;
   while (rangeList.extract(rangesData, &offset))
     rangeList.dump(OS);

   OS << "\n.debug_abbrev.dwo contents:\n";
   getDebugAbbrevDWO()->dump(OS);

   OS << "\n.debug_info.dwo contents:\n";
   for (unsigned i = 0, e = getNumDWOCompileUnits(); i != e; ++i)
     getDWOCompileUnitAtIndex(i)->dump(OS);

   OS << "\n.debug_str.dwo contents:\n";
   DataExtractor strDWOData(getStringDWOSection(), isLittleEndian(), 0);
   offset = 0;
   uint32_t strDWOOffset = 0;
   while (const char *s = strDWOData.getCStr(&offset)) {
     OS << format("0x%8.8x: \"%s\"\n", strDWOOffset, s);
     strDWOOffset = offset;
   }
 }

 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrev() {
   if (Abbrev)
     return Abbrev.get();

   DataExtractor abbrData(getAbbrevSection(), isLittleEndian(), 0);

   Abbrev.reset(new DWARFDebugAbbrev());
   Abbrev->parse(abbrData);
   return Abbrev.get();
 }

 const DWARFDebugAbbrev *DWARFContext::getDebugAbbrevDWO() {
   if (AbbrevDWO)
     return AbbrevDWO.get();

   DataExtractor abbrData(getAbbrevDWOSection(), isLittleEndian(), 0);
   AbbrevDWO.reset(new DWARFDebugAbbrev());
   AbbrevDWO->parse(abbrData);
   return AbbrevDWO.get();
 }

 const DWARFDebugAranges *DWARFContext::getDebugAranges() {
   if (Aranges)
     return Aranges.get();

   DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);

   Aranges.reset(new DWARFDebugAranges());
   Aranges->extract(arangesData);
   // Generate aranges from DIEs: even if .debug_aranges section is present,
   // it may describe only a small subset of compilation units, so we need to
   // manually build aranges for the rest of them.
   Aranges->generate(this);
   return Aranges.get();
 }

 const DWARFLineTable *
 DWARFContext::getLineTableForCompileUnit(DWARFCompileUnit *cu) {
   if (!Line)
     Line.reset(new DWARFDebugLine());

   unsigned stmtOffset =
     cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_stmt_list,
                                                          -1U);
   if (stmtOffset == -1U)
     return 0; // No line table for this compile unit.

   // See if the line table is cached.
   if (const DWARFLineTable *lt = Line->getLineTable(stmtOffset))
     return lt;

   // We have to parse it first.
   DataExtractor lineData(getLineSection(), isLittleEndian(),
                          cu->getAddressByteSize());
   return Line->getOrParseLineTable(lineData, stmtOffset);
 }

 void DWARFContext::parseCompileUnits() {
   uint32_t offset = 0;
   const DataExtractor &DIData = DataExtractor(getInfoSection(),
                                               isLittleEndian(), 0);
   while (DIData.isValidOffset(offset)) {
     CUs.push_back(DWARFCompileUnit(getDebugAbbrev(), getInfoSection(),
                                    getAbbrevSection(), getRangeSection(),
                                    getStringSection(), &infoRelocMap(),
                                    isLittleEndian()));
     if (!CUs.back().extract(DIData, &offset)) {
       CUs.pop_back();
       break;
     }

     offset = CUs.back().getNextCompileUnitOffset();
   }
 }

 void DWARFContext::parseDWOCompileUnits() {
   uint32_t offset = 0;
   const DataExtractor &DIData = DataExtractor(getInfoDWOSection(),
                                               isLittleEndian(), 0);
   while (DIData.isValidOffset(offset)) {
     DWOCUs.push_back(DWARFCompileUnit(getDebugAbbrevDWO(), getInfoDWOSection(),
                                       getAbbrevDWOSection(),
                                       getRangeDWOSection(),
                                       getStringDWOSection(),
                                       &infoDWORelocMap(),
                                       isLittleEndian()));
     if (!DWOCUs.back().extract(DIData, &offset)) {
       DWOCUs.pop_back();
       break;
     }

     offset = DWOCUs.back().getNextCompileUnitOffset();
   }
 }

 namespace {
   struct OffsetComparator {
     bool operator()(const DWARFCompileUnit &LHS,
                     const DWARFCompileUnit &RHS) const {
       return LHS.getOffset() < RHS.getOffset();
     }
     bool operator()(const DWARFCompileUnit &LHS, uint32_t RHS) const {
       return LHS.getOffset() < RHS;
     }
     bool operator()(uint32_t LHS, const DWARFCompileUnit &RHS) const {
       return LHS < RHS.getOffset();
     }
   };
 }

 DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t Offset) {
   if (CUs.empty())
     parseCompileUnits();

   DWARFCompileUnit *CU = std::lower_bound(CUs.begin(), CUs.end(), Offset,
                                           OffsetComparator());
   if (CU != CUs.end())
     return &*CU;
   return 0;
 }

 DWARFCompileUnit *DWARFContext::getCompileUnitForAddress(uint64_t Address) {
   // First, get the offset of the compile unit.
   uint32_t CUOffset = getDebugAranges()->findAddress(Address);
   // Retrieve the compile unit.
   return getCompileUnitForOffset(CUOffset);
 }

 static bool getFileNameForCompileUnit(DWARFCompileUnit *CU,
                                       const DWARFLineTable *LineTable,
                                       uint64_t FileIndex,
                                       bool NeedsAbsoluteFilePath,
                                       std::string &FileName) {
   if (CU == 0 ||
       LineTable == 0 ||
       !LineTable->getFileNameByIndex(FileIndex, NeedsAbsoluteFilePath,
                                      FileName))
     return false;
   if (NeedsAbsoluteFilePath && sys::path::is_relative(FileName)) {
     // We may still need to append compilation directory of compile unit.
     SmallString<16> AbsolutePath;
     if (const char *CompilationDir = CU->getCompilationDir()) {
       sys::path::append(AbsolutePath, CompilationDir);
     }
     sys::path::append(AbsolutePath, FileName);
     FileName = AbsolutePath.str();
   }
   return true;
 }

 static bool getFileLineInfoForCompileUnit(DWARFCompileUnit *CU,
                                           const DWARFLineTable *LineTable,
                                           uint64_t Address,
                                           bool NeedsAbsoluteFilePath,
                                           std::string &FileName,
                                           uint32_t &Line, uint32_t &Column) {
   if (CU == 0 || LineTable == 0)
     return false;
   // Get the index of row we're looking for in the line table.
   uint32_t RowIndex = LineTable->lookupAddress(Address);
   if (RowIndex == -1U)
     return false;
   // Take file number and line/column from the row.
   const DWARFDebugLine::Row &Row = LineTable->Rows[RowIndex];
   if (!getFileNameForCompileUnit(CU, LineTable, Row.File,
                                  NeedsAbsoluteFilePath, FileName))
     return false;
   Line = Row.Line;
   Column = Row.Column;
   return true;
 }

 DILineInfo DWARFContext::getLineInfoForAddress(uint64_t Address,
     DILineInfoSpecifier Specifier) {
   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
   if (!CU)
     return DILineInfo();
   std::string FileName = "<invalid>";
   std::string FunctionName = "<invalid>";
   uint32_t Line = 0;
   uint32_t Column = 0;
   if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
     // The address may correspond to instruction in some inlined function,
     // so we have to build the chain of inlined functions and take the
     // name of the topmost function in it.
     const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
         CU->getInlinedChainForAddress(Address);
     if (InlinedChain.size() > 0) {
       const DWARFDebugInfoEntryMinimal &TopFunctionDIE = InlinedChain[0];
       if (const char *Name = TopFunctionDIE.getSubroutineName(CU))
         FunctionName = Name;
     }
   }
   if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
     const DWARFLineTable *LineTable = getLineTableForCompileUnit(CU);
     const bool NeedsAbsoluteFilePath =
         Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
     getFileLineInfoForCompileUnit(CU, LineTable, Address,
                                   NeedsAbsoluteFilePath,
                                   FileName, Line, Column);
   }
   return DILineInfo(StringRef(FileName), StringRef(FunctionName),
                     Line, Column);
 }

 DIInliningInfo DWARFContext::getInliningInfoForAddress(uint64_t Address,
     DILineInfoSpecifier Specifier) {
   DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
   if (!CU)
     return DIInliningInfo();

   const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
       CU->getInlinedChainForAddress(Address);
   if (InlinedChain.size() == 0)
     return DIInliningInfo();

   DIInliningInfo InliningInfo;
   uint32_t CallFile = 0, CallLine = 0, CallColumn = 0;
   const DWARFLineTable *LineTable = 0;
   for (uint32_t i = 0, n = InlinedChain.size(); i != n; i++) {
     const DWARFDebugInfoEntryMinimal &FunctionDIE = InlinedChain[i];
     std::string FileName = "<invalid>";
     std::string FunctionName = "<invalid>";
     uint32_t Line = 0;
     uint32_t Column = 0;
     // Get function name if necessary.
     if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
       if (const char *Name = FunctionDIE.getSubroutineName(CU))
         FunctionName = Name;
     }
     if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
       const bool NeedsAbsoluteFilePath =
           Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
       if (i == 0) {
         // For the topmost frame, initialize the line table of this
         // compile unit and fetch file/line info from it.
         LineTable = getLineTableForCompileUnit(CU);
         // For the topmost routine, get file/line info from line table.
         getFileLineInfoForCompileUnit(CU, LineTable, Address,
                                       NeedsAbsoluteFilePath,
                                       FileName, Line, Column);
       } else {
         // Otherwise, use call file, call line and call column from
         // previous DIE in inlined chain.
         getFileNameForCompileUnit(CU, LineTable, CallFile,
                                   NeedsAbsoluteFilePath, FileName);
         Line = CallLine;
         Column = CallColumn;
       }
       // Get call file/line/column of a current DIE.
       if (i + 1 < n) {
         FunctionDIE.getCallerFrame(CU, CallFile, CallLine, CallColumn);
       }
     }
     DILineInfo Frame(StringRef(FileName), StringRef(FunctionName),
                      Line, Column);
     InliningInfo.addFrame(Frame);
   }
   return InliningInfo;
 }

 DWARFContextInMemory::DWARFContextInMemory(object::ObjectFile *Obj) :
   IsLittleEndian(true /* FIXME */) {
   error_code ec;
   for (object::section_iterator i = Obj->begin_sections(),
          e = Obj->end_sections();
        i != e; i.increment(ec)) {
     StringRef name;
     i->getName(name);
     StringRef data;
     i->getContents(data);

     name = name.substr(name.find_first_not_of("._")); // Skip . and _ prefixes.
     if (name == "debug_info")
       InfoSection = data;
     else if (name == "debug_abbrev")
       AbbrevSection = data;
     else if (name == "debug_line")
       LineSection = data;
     else if (name == "debug_aranges")
       ARangeSection = data;
     else if (name == "debug_str")
       StringSection = data;
     else if (name == "debug_ranges") {
       // FIXME: Use the other dwo range section when we emit it.
       RangeDWOSection = data;
       RangeSection = data;
     }
     else if (name == "debug_info.dwo")
       InfoDWOSection = data;
     else if (name == "debug_abbrev.dwo")
       AbbrevDWOSection = data;
     else if (name == "debug_str.dwo")
       StringDWOSection = data;
     // Any more debug info sections go here.
     else
       continue;

     // TODO: For now only handle relocations for the debug_info section.
     RelocAddrMap *Map;
     if (name == "debug_info")
       Map = &InfoRelocMap;
     else if (name == "debug_info.dwo")
       Map = &InfoDWORelocMap;
     else
       continue;

     if (i->begin_relocations() != i->end_relocations()) {
       uint64_t SectionSize;
       i->getSize(SectionSize);
       for (object::relocation_iterator reloc_i = i->begin_relocations(),
              reloc_e = i->end_relocations();
            reloc_i != reloc_e; reloc_i.increment(ec)) {
         uint64_t Address;
         reloc_i->getAddress(Address);
         uint64_t Type;
         reloc_i->getType(Type);

         object::RelocVisitor V(Obj->getFileFormatName());
         // The section address is always 0 for debug sections.
         object::RelocToApply R(V.visit(Type, *reloc_i));
         if (V.error()) {
           SmallString<32> Name;
           error_code ec(reloc_i->getTypeName(Name));
           if (ec) {
             errs() << "Aaaaaa! Nameless relocation! Aaaaaa!\n";
           }
           errs() << "error: failed to compute relocation: "
                  << Name << "\n";
           continue;
         }

         if (Address + R.Width > SectionSize) {
           errs() << "error: " << R.Width << "-byte relocation starting "
                  << Address << " bytes into section " << name << " which is "
                  << SectionSize << " bytes long.\n";
           continue;
         }
         if (R.Width > 8) {
           errs() << "error: can't handle a relocation of more than 8 bytes at "
                     "a time.\n";
           continue;
         }
         DEBUG(dbgs() << "Writing " << format("%p", R.Value)
                      << " at " << format("%p", Address)
                      << " with width " << format("%d", R.Width)
                      << "\n");
         Map->insert(std::make_pair(Address, std::make_pair(R.Width, R.Value)));
       }
     }
   }
 }

 void DWARFContextInMemory::anchor() { }
	//===-- DWARFContext.cpp --------------------------------------------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//

	#include "DWARFContext.h"
	#include "llvm/ADT/SmallString.h"
	#include "llvm/Support/Dwarf.h"
	#include "llvm/Support/Format.h"
	#include "llvm/Support/Path.h"
	#include "llvm/Support/raw_ostream.h"
	#include <algorithm>
	using namespace llvm;
	using namespace dwarf;

	typedef DWARFDebugLine::LineTable DWARFLineTable;

	void DWARFContext::dump(raw_ostream &OS) {
	OS << ".debug_abbrev contents:\n";
	getDebugAbbrev()->dump(OS);

	OS << "\n.debug_info contents:\n";
	for (unsigned i = 0, e = getNumCompileUnits(); i != e; ++i)
	getCompileUnitAtIndex(i)->dump(OS);

	OS << "\n.debug_aranges contents:\n";
	DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);
	uint32_t offset = 0;
	DWARFDebugArangeSet set;
	while (set.extract(arangesData, &offset))
	set.dump(OS);

	uint8_t savedAddressByteSize = 0;
	OS << "\n.debug_line contents:\n";
	for (unsigned i = 0, e = getNumCompileUnits(); i != e; ++i) {
	DWARFCompileUnit *cu = getCompileUnitAtIndex(i);
	savedAddressByteSize = cu->getAddressByteSize();
	unsigned stmtOffset =
	cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_stmt_list,
	-1U);
	if (stmtOffset != -1U) {
	DataExtractor lineData(getLineSection(), isLittleEndian(),
	savedAddressByteSize);
	DWARFDebugLine::DumpingState state(OS);
	DWARFDebugLine::parseStatementTable(lineData, &stmtOffset, state);
	}
	}

	OS << "\n.debug_str contents:\n";
	DataExtractor strData(getStringSection(), isLittleEndian(), 0);
	offset = 0;
	uint32_t strOffset = 0;
	while (const char *s = strData.getCStr(&offset)) {
	OS << format("0x%8.8x: \"%s\"\n", strOffset, s);
	strOffset = offset;
	}

	OS << "\n.debug_ranges contents:\n";
	// In fact, different compile units may have different address byte
	// sizes, but for simplicity we just use the address byte size of the last
	// compile unit (there is no easy and fast way to associate address range
	// list and the compile unit it describes).
	DataExtractor rangesData(getRangeSection(), isLittleEndian(),
	savedAddressByteSize);
	offset = 0;
	DWARFDebugRangeList rangeList;
	while (rangeList.extract(rangesData, &offset))
	rangeList.dump(OS);

	OS << "\n.debug_abbrev.dwo contents:\n";
	getDebugAbbrevDWO()->dump(OS);

	OS << "\n.debug_info.dwo contents:\n";
	for (unsigned i = 0, e = getNumDWOCompileUnits(); i != e; ++i)
	getDWOCompileUnitAtIndex(i)->dump(OS);

	OS << "\n.debug_str.dwo contents:\n";
	DataExtractor strDWOData(getStringDWOSection(), isLittleEndian(), 0);
	offset = 0;
	uint32_t strDWOOffset = 0;
	while (const char *s = strDWOData.getCStr(&offset)) {
	OS << format("0x%8.8x: \"%s\"\n", strDWOOffset, s);
	strDWOOffset = offset;
	}
	}

	const DWARFDebugAbbrev *DWARFContext::getDebugAbbrev() {
	if (Abbrev)
	return Abbrev.get();

	DataExtractor abbrData(getAbbrevSection(), isLittleEndian(), 0);

	Abbrev.reset(new DWARFDebugAbbrev());
	Abbrev->parse(abbrData);
	return Abbrev.get();
	}

	const DWARFDebugAbbrev *DWARFContext::getDebugAbbrevDWO() {
	if (AbbrevDWO)
	return AbbrevDWO.get();

	DataExtractor abbrData(getAbbrevDWOSection(), isLittleEndian(), 0);
	AbbrevDWO.reset(new DWARFDebugAbbrev());
	AbbrevDWO->parse(abbrData);
	return AbbrevDWO.get();
	}

	const DWARFDebugAranges *DWARFContext::getDebugAranges() {
	if (Aranges)
	return Aranges.get();

	DataExtractor arangesData(getARangeSection(), isLittleEndian(), 0);

	Aranges.reset(new DWARFDebugAranges());
	Aranges->extract(arangesData);
	// Generate aranges from DIEs: even if .debug_aranges section is present,
	// it may describe only a small subset of compilation units, so we need to
	// manually build aranges for the rest of them.
	Aranges->generate(this);
	return Aranges.get();
	}

	const DWARFLineTable *
	DWARFContext::getLineTableForCompileUnit(DWARFCompileUnit *cu) {
	if (!Line)
	Line.reset(new DWARFDebugLine());

	unsigned stmtOffset =
	cu->getCompileUnitDIE()->getAttributeValueAsUnsigned(cu, DW_AT_stmt_list,
	-1U);
	if (stmtOffset == -1U)
	return 0; // No line table for this compile unit.

	// See if the line table is cached.
	if (const DWARFLineTable *lt = Line->getLineTable(stmtOffset))
	return lt;

	// We have to parse it first.
	DataExtractor lineData(getLineSection(), isLittleEndian(),
	cu->getAddressByteSize());
	return Line->getOrParseLineTable(lineData, stmtOffset);
	}

	void DWARFContext::parseCompileUnits() {
	uint32_t offset = 0;
	const DataExtractor &DIData = DataExtractor(getInfoSection(),
	isLittleEndian(), 0);
	while (DIData.isValidOffset(offset)) {
	CUs.push_back(DWARFCompileUnit(getDebugAbbrev(), getInfoSection(),
	getAbbrevSection(), getRangeSection(),
	getStringSection(), &infoRelocMap(),
	isLittleEndian()));
	if (!CUs.back().extract(DIData, &offset)) {
	CUs.pop_back();
	break;
	}

	offset = CUs.back().getNextCompileUnitOffset();
	}
	}

	void DWARFContext::parseDWOCompileUnits() {
	uint32_t offset = 0;
	const DataExtractor &DIData = DataExtractor(getInfoDWOSection(),
	isLittleEndian(), 0);
	while (DIData.isValidOffset(offset)) {
	DWOCUs.push_back(DWARFCompileUnit(getDebugAbbrevDWO(), getInfoDWOSection(),
	getAbbrevDWOSection(),
	getRangeDWOSection(),
	getStringDWOSection(),
	&infoDWORelocMap(),
	isLittleEndian()));
	if (!DWOCUs.back().extract(DIData, &offset)) {
	DWOCUs.pop_back();
	break;
	}

	offset = DWOCUs.back().getNextCompileUnitOffset();
	}
	}

	namespace {
	struct OffsetComparator {
	bool operator()(const DWARFCompileUnit &LHS,
	const DWARFCompileUnit &RHS) const {
	return LHS.getOffset() < RHS.getOffset();
	}
	bool operator()(const DWARFCompileUnit &LHS, uint32_t RHS) const {
	return LHS.getOffset() < RHS;
	}
	bool operator()(uint32_t LHS, const DWARFCompileUnit &RHS) const {
	return LHS < RHS.getOffset();
	}
	};
	}

	DWARFCompileUnit *DWARFContext::getCompileUnitForOffset(uint32_t Offset) {
	if (CUs.empty())
	parseCompileUnits();

	DWARFCompileUnit *CU = std::lower_bound(CUs.begin(), CUs.end(), Offset,
	OffsetComparator());
	if (CU != CUs.end())
	return &*CU;
	return 0;
	}

	DWARFCompileUnit *DWARFContext::getCompileUnitForAddress(uint64_t Address) {
	// First, get the offset of the compile unit.
	uint32_t CUOffset = getDebugAranges()->findAddress(Address);
	// Retrieve the compile unit.
	return getCompileUnitForOffset(CUOffset);
	}

	static bool getFileNameForCompileUnit(DWARFCompileUnit *CU,
	const DWARFLineTable *LineTable,
	uint64_t FileIndex,
	bool NeedsAbsoluteFilePath,
	std::string &FileName) {
	if (CU == 0 \|\|
	LineTable == 0 \|\|
	!LineTable->getFileNameByIndex(FileIndex, NeedsAbsoluteFilePath,
	FileName))
	return false;
	if (NeedsAbsoluteFilePath && sys::path::is_relative(FileName)) {
	// We may still need to append compilation directory of compile unit.
	SmallString<16> AbsolutePath;
	if (const char *CompilationDir = CU->getCompilationDir()) {
	sys::path::append(AbsolutePath, CompilationDir);
	}
	sys::path::append(AbsolutePath, FileName);
	FileName = AbsolutePath.str();
	}
	return true;
	}

	static bool getFileLineInfoForCompileUnit(DWARFCompileUnit *CU,
	const DWARFLineTable *LineTable,
	uint64_t Address,
	bool NeedsAbsoluteFilePath,
	std::string &FileName,
	uint32_t &Line, uint32_t &Column) {
	if (CU == 0 \|\| LineTable == 0)
	return false;
	// Get the index of row we're looking for in the line table.
	uint32_t RowIndex = LineTable->lookupAddress(Address);
	if (RowIndex == -1U)
	return false;
	// Take file number and line/column from the row.
	const DWARFDebugLine::Row &Row = LineTable->Rows[RowIndex];
	if (!getFileNameForCompileUnit(CU, LineTable, Row.File,
	NeedsAbsoluteFilePath, FileName))
	return false;
	Line = Row.Line;
	Column = Row.Column;
	return true;
	}

	DILineInfo DWARFContext::getLineInfoForAddress(uint64_t Address,
	DILineInfoSpecifier Specifier) {
	DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
	if (!CU)
	return DILineInfo();
	std::string FileName = "<invalid>";
	std::string FunctionName = "<invalid>";
	uint32_t Line = 0;
	uint32_t Column = 0;
	if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
	// The address may correspond to instruction in some inlined function,
	// so we have to build the chain of inlined functions and take the
	// name of the topmost function in it.
	const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
	CU->getInlinedChainForAddress(Address);
	if (InlinedChain.size() > 0) {
	const DWARFDebugInfoEntryMinimal &TopFunctionDIE = InlinedChain[0];
	if (const char *Name = TopFunctionDIE.getSubroutineName(CU))
	FunctionName = Name;
	}
	}
	if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
	const DWARFLineTable *LineTable = getLineTableForCompileUnit(CU);
	const bool NeedsAbsoluteFilePath =
	Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
	getFileLineInfoForCompileUnit(CU, LineTable, Address,
	NeedsAbsoluteFilePath,
	FileName, Line, Column);
	}
	return DILineInfo(StringRef(FileName), StringRef(FunctionName),
	Line, Column);
	}

	DIInliningInfo DWARFContext::getInliningInfoForAddress(uint64_t Address,
	DILineInfoSpecifier Specifier) {
	DWARFCompileUnit *CU = getCompileUnitForAddress(Address);
	if (!CU)
	return DIInliningInfo();

	const DWARFDebugInfoEntryMinimal::InlinedChain &InlinedChain =
	CU->getInlinedChainForAddress(Address);
	if (InlinedChain.size() == 0)
	return DIInliningInfo();

	DIInliningInfo InliningInfo;
	uint32_t CallFile = 0, CallLine = 0, CallColumn = 0;
	const DWARFLineTable *LineTable = 0;
	for (uint32_t i = 0, n = InlinedChain.size(); i != n; i++) {
	const DWARFDebugInfoEntryMinimal &FunctionDIE = InlinedChain[i];
	std::string FileName = "<invalid>";
	std::string FunctionName = "<invalid>";
	uint32_t Line = 0;
	uint32_t Column = 0;
	// Get function name if necessary.
	if (Specifier.needs(DILineInfoSpecifier::FunctionName)) {
	if (const char *Name = FunctionDIE.getSubroutineName(CU))
	FunctionName = Name;
	}
	if (Specifier.needs(DILineInfoSpecifier::FileLineInfo)) {
	const bool NeedsAbsoluteFilePath =
	Specifier.needs(DILineInfoSpecifier::AbsoluteFilePath);
	if (i == 0) {
	// For the topmost frame, initialize the line table of this
	// compile unit and fetch file/line info from it.
	LineTable = getLineTableForCompileUnit(CU);
	// For the topmost routine, get file/line info from line table.
	getFileLineInfoForCompileUnit(CU, LineTable, Address,
	NeedsAbsoluteFilePath,
	FileName, Line, Column);
	} else {
	// Otherwise, use call file, call line and call column from
	// previous DIE in inlined chain.
	getFileNameForCompileUnit(CU, LineTable, CallFile,
	NeedsAbsoluteFilePath, FileName);
	Line = CallLine;
	Column = CallColumn;
	}
	// Get call file/line/column of a current DIE.
	if (i + 1 < n) {
	FunctionDIE.getCallerFrame(CU, CallFile, CallLine, CallColumn);
	}
	}
	DILineInfo Frame(StringRef(FileName), StringRef(FunctionName),
	Line, Column);
	InliningInfo.addFrame(Frame);
	}
	return InliningInfo;
	}

	DWARFContextInMemory::DWARFContextInMemory(object::ObjectFile *Obj) :
	IsLittleEndian(true /* FIXME */) {
	error_code ec;
	for (object::section_iterator i = Obj->begin_sections(),
	e = Obj->end_sections();
	i != e; i.increment(ec)) {
	StringRef name;
	i->getName(name);
	StringRef data;
	i->getContents(data);

	name = name.substr(name.find_first_not_of("._")); // Skip . and _ prefixes.
	if (name == "debug_info")
	InfoSection = data;
	else if (name == "debug_abbrev")
	AbbrevSection = data;
	else if (name == "debug_line")
	LineSection = data;
	else if (name == "debug_aranges")
	ARangeSection = data;
	else if (name == "debug_str")
	StringSection = data;
	else if (name == "debug_ranges") {
	// FIXME: Use the other dwo range section when we emit it.
	RangeDWOSection = data;
	RangeSection = data;
	}
	else if (name == "debug_info.dwo")
	InfoDWOSection = data;
	else if (name == "debug_abbrev.dwo")
	AbbrevDWOSection = data;
	else if (name == "debug_str.dwo")
	StringDWOSection = data;
	// Any more debug info sections go here.
	else
	continue;

	// TODO: For now only handle relocations for the debug_info section.
	RelocAddrMap *Map;
	if (name == "debug_info")
	Map = &InfoRelocMap;
	else if (name == "debug_info.dwo")
	Map = &InfoDWORelocMap;
	else
	continue;

	if (i->begin_relocations() != i->end_relocations()) {
	uint64_t SectionSize;
	i->getSize(SectionSize);
	for (object::relocation_iterator reloc_i = i->begin_relocations(),
	reloc_e = i->end_relocations();
	reloc_i != reloc_e; reloc_i.increment(ec)) {
	uint64_t Address;
	reloc_i->getAddress(Address);
	uint64_t Type;
	reloc_i->getType(Type);

	object::RelocVisitor V(Obj->getFileFormatName());
	// The section address is always 0 for debug sections.
	object::RelocToApply R(V.visit(Type, *reloc_i));
	if (V.error()) {
	SmallString<32> Name;
	error_code ec(reloc_i->getTypeName(Name));
	if (ec) {
	errs() << "Aaaaaa! Nameless relocation! Aaaaaa!\n";
	}
	errs() << "error: failed to compute relocation: "
	<< Name << "\n";
	continue;
	}

	if (Address + R.Width > SectionSize) {
	errs() << "error: " << R.Width << "-byte relocation starting "
	<< Address << " bytes into section " << name << " which is "
	<< SectionSize << " bytes long.\n";
	continue;
	}
	if (R.Width > 8) {
	errs() << "error: can't handle a relocation of more than 8 bytes at "
	"a time.\n";
	continue;
	}
	DEBUG(dbgs() << "Writing " << format("%p", R.Value)
	<< " at " << format("%p", Address)
	<< " with width " << format("%d", R.Width)
	<< "\n");
	Map->insert(std::make_pair(Address, std::make_pair(R.Width, R.Value)));
	}
	}
	}
	}

	void DWARFContextInMemory::anchor() { }