diff options
Diffstat (limited to 'tools/dsymutil/DwarfLinker.cpp')
| -rw-r--r-- | tools/dsymutil/DwarfLinker.cpp | 1934 |
1 files changed, 1904 insertions, 30 deletions
diff --git a/tools/dsymutil/DwarfLinker.cpp b/tools/dsymutil/DwarfLinker.cpp index 3c0bc0b..c9c05cd 100644 --- a/tools/dsymutil/DwarfLinker.cpp +++ b/tools/dsymutil/DwarfLinker.cpp @@ -10,19 +10,55 @@ #include "BinaryHolder.h" #include "DebugMap.h" #include "dsymutil.h" +#include "llvm/ADT/IntervalMap.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/CodeGen/AsmPrinter.h" +#include "llvm/CodeGen/DIE.h" #include "llvm/DebugInfo/DWARF/DWARFContext.h" #include "llvm/DebugInfo/DWARF/DWARFDebugInfoEntry.h" #include "llvm/DebugInfo/DWARF/DWARFFormValue.h" +#include "llvm/MC/MCAsmBackend.h" +#include "llvm/MC/MCAsmInfo.h" +#include "llvm/MC/MCContext.h" +#include "llvm/MC/MCCodeEmitter.h" +#include "llvm/MC/MCDwarf.h" +#include "llvm/MC/MCInstrInfo.h" +#include "llvm/MC/MCObjectFileInfo.h" +#include "llvm/MC/MCRegisterInfo.h" +#include "llvm/MC/MCStreamer.h" #include "llvm/Object/MachO.h" #include "llvm/Support/Dwarf.h" #include "llvm/Support/LEB128.h" +#include "llvm/Support/TargetRegistry.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetOptions.h" #include <string> +#include <tuple> namespace llvm { namespace dsymutil { namespace { +void warn(const Twine &Warning, const Twine &Context) { + errs() << Twine("while processing ") + Context + ":\n"; + errs() << Twine("warning: ") + Warning + "\n"; +} + +bool error(const Twine &Error, const Twine &Context) { + errs() << Twine("while processing ") + Context + ":\n"; + errs() << Twine("error: ") + Error + "\n"; + return false; +} + +template <typename KeyT, typename ValT> +using HalfOpenIntervalMap = + IntervalMap<KeyT, ValT, IntervalMapImpl::NodeSizer<KeyT, ValT>::LeafSize, + IntervalMapHalfOpenInfo<KeyT>>; + +typedef HalfOpenIntervalMap<uint64_t, int64_t> FunctionIntervals; + /// \brief Stores all information relating to a compile unit, be it in /// its original instance in the object file to its brand new cloned /// and linked DIE tree. @@ -30,26 +66,900 @@ class CompileUnit { public: /// \brief Information gathered about a DIE in the object file. struct DIEInfo { - uint64_t Address; ///< Linked address of the described entity. + int64_t AddrAdjust; ///< Address offset to apply to the described entity. + DIE *Clone; ///< Cloned version of that DIE. uint32_t ParentIdx; ///< The index of this DIE's parent. bool Keep; ///< Is the DIE part of the linked output? bool InDebugMap; ///< Was this DIE's entity found in the map? }; - CompileUnit(DWARFUnit &OrigUnit) : OrigUnit(OrigUnit) { + CompileUnit(DWARFUnit &OrigUnit, unsigned ID) + : OrigUnit(OrigUnit), ID(ID), LowPc(UINT64_MAX), HighPc(0), RangeAlloc(), + Ranges(RangeAlloc), UnitRangeAttribute(nullptr) { Info.resize(OrigUnit.getNumDIEs()); } + CompileUnit(CompileUnit &&RHS) + : OrigUnit(RHS.OrigUnit), Info(std::move(RHS.Info)), + CUDie(std::move(RHS.CUDie)), StartOffset(RHS.StartOffset), + NextUnitOffset(RHS.NextUnitOffset), RangeAlloc(), Ranges(RangeAlloc) { + // The CompileUnit container has been 'reserve()'d with the right + // size. We cannot move the IntervalMap anyway. + llvm_unreachable("CompileUnits should not be moved."); + } + DWARFUnit &getOrigUnit() const { return OrigUnit; } + unsigned getUniqueID() const { return ID; } + + DIE *getOutputUnitDIE() const { return CUDie.get(); } + void setOutputUnitDIE(DIE *Die) { CUDie.reset(Die); } + DIEInfo &getInfo(unsigned Idx) { return Info[Idx]; } const DIEInfo &getInfo(unsigned Idx) const { return Info[Idx]; } + uint64_t getStartOffset() const { return StartOffset; } + uint64_t getNextUnitOffset() const { return NextUnitOffset; } + void setStartOffset(uint64_t DebugInfoSize) { StartOffset = DebugInfoSize; } + + uint64_t getLowPc() const { return LowPc; } + uint64_t getHighPc() const { return HighPc; } + + DIEInteger *getUnitRangesAttribute() const { return UnitRangeAttribute; } + const FunctionIntervals &getFunctionRanges() const { return Ranges; } + const std::vector<DIEInteger *> &getRangesAttributes() const { + return RangeAttributes; + } + + const std::vector<std::pair<DIEInteger *, int64_t>> & + getLocationAttributes() const { + return LocationAttributes; + } + + /// \brief Compute the end offset for this unit. Must be + /// called after the CU's DIEs have been cloned. + /// \returns the next unit offset (which is also the current + /// debug_info section size). + uint64_t computeNextUnitOffset(); + + /// \brief Keep track of a forward reference to DIE \p Die in \p + /// RefUnit by \p Attr. The attribute should be fixed up later to + /// point to the absolute offset of \p Die in the debug_info section. + void noteForwardReference(DIE *Die, const CompileUnit *RefUnit, + DIEInteger *Attr); + + /// \brief Apply all fixups recored by noteForwardReference(). + void fixupForwardReferences(); + + /// \brief Add a function range [\p LowPC, \p HighPC) that is + /// relocatad by applying offset \p PCOffset. + void addFunctionRange(uint64_t LowPC, uint64_t HighPC, int64_t PCOffset); + + /// \brief Keep track of a DW_AT_range attribute that we will need to + /// patch up later. + void noteRangeAttribute(const DIE &Die, DIEInteger *Attr); + + /// \brief Keep track of a location attribute pointing to a location + /// list in the debug_loc section. + void noteLocationAttribute(DIEInteger *Attr, int64_t PcOffset); + + /// \brief Add a name accelerator entry for \p Die with \p Name + /// which is stored in the string table at \p Offset. + void addNameAccelerator(const DIE *Die, const char *Name, uint32_t Offset, + bool SkipPubnamesSection = false); + + /// \brief Add a type accelerator entry for \p Die with \p Name + /// which is stored in the string table at \p Offset. + void addTypeAccelerator(const DIE *Die, const char *Name, uint32_t Offset); + + struct AccelInfo { + StringRef Name; ///< Name of the entry. + const DIE *Die; ///< DIE this entry describes. + uint32_t NameOffset; ///< Offset of Name in the string pool. + bool SkipPubSection; ///< Emit this entry only in the apple_* sections. + + AccelInfo(StringRef Name, const DIE *Die, uint32_t NameOffset, + bool SkipPubSection = false) + : Name(Name), Die(Die), NameOffset(NameOffset), + SkipPubSection(SkipPubSection) {} + }; + + const std::vector<AccelInfo> &getPubnames() const { return Pubnames; } + const std::vector<AccelInfo> &getPubtypes() const { return Pubtypes; } + private: DWARFUnit &OrigUnit; - std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index. + unsigned ID; + std::vector<DIEInfo> Info; ///< DIE info indexed by DIE index. + std::unique_ptr<DIE> CUDie; ///< Root of the linked DIE tree. + + uint64_t StartOffset; + uint64_t NextUnitOffset; + + uint64_t LowPc; + uint64_t HighPc; + + /// \brief A list of attributes to fixup with the absolute offset of + /// a DIE in the debug_info section. + /// + /// The offsets for the attributes in this array couldn't be set while + /// cloning because for cross-cu forward refences the target DIE's + /// offset isn't known you emit the reference attribute. + std::vector<std::tuple<DIE *, const CompileUnit *, DIEInteger *>> + ForwardDIEReferences; + + FunctionIntervals::Allocator RangeAlloc; + /// \brief The ranges in that interval map are the PC ranges for + /// functions in this unit, associated with the PC offset to apply + /// to the addresses to get the linked address. + FunctionIntervals Ranges; + + /// \brief DW_AT_ranges attributes to patch after we have gathered + /// all the unit's function addresses. + /// @{ + std::vector<DIEInteger *> RangeAttributes; + DIEInteger *UnitRangeAttribute; + /// @} + + /// \brief Location attributes that need to be transfered from th + /// original debug_loc section to the liked one. They are stored + /// along with the PC offset that is to be applied to their + /// function's address. + std::vector<std::pair<DIEInteger *, int64_t>> LocationAttributes; + + /// \brief Accelerator entries for the unit, both for the pub* + /// sections and the apple* ones. + /// @{ + std::vector<AccelInfo> Pubnames; + std::vector<AccelInfo> Pubtypes; + /// @} +}; + +uint64_t CompileUnit::computeNextUnitOffset() { + NextUnitOffset = StartOffset + 11 /* Header size */; + // The root DIE might be null, meaning that the Unit had nothing to + // contribute to the linked output. In that case, we will emit the + // unit header without any actual DIE. + if (CUDie) + NextUnitOffset += CUDie->getSize(); + return NextUnitOffset; +} + +/// \brief Keep track of a forward cross-cu reference from this unit +/// to \p Die that lives in \p RefUnit. +void CompileUnit::noteForwardReference(DIE *Die, const CompileUnit *RefUnit, + DIEInteger *Attr) { + ForwardDIEReferences.emplace_back(Die, RefUnit, Attr); +} + +/// \brief Apply all fixups recorded by noteForwardReference(). +void CompileUnit::fixupForwardReferences() { + for (const auto &Ref : ForwardDIEReferences) { + DIE *RefDie; + const CompileUnit *RefUnit; + DIEInteger *Attr; + std::tie(RefDie, RefUnit, Attr) = Ref; + Attr->setValue(RefDie->getOffset() + RefUnit->getStartOffset()); + } +} + +void CompileUnit::addFunctionRange(uint64_t FuncLowPc, uint64_t FuncHighPc, + int64_t PcOffset) { + Ranges.insert(FuncLowPc, FuncHighPc, PcOffset); + this->LowPc = std::min(LowPc, FuncLowPc + PcOffset); + this->HighPc = std::max(HighPc, FuncHighPc + PcOffset); +} + +void CompileUnit::noteRangeAttribute(const DIE &Die, DIEInteger *Attr) { + if (Die.getTag() != dwarf::DW_TAG_compile_unit) + RangeAttributes.push_back(Attr); + else + UnitRangeAttribute = Attr; +} + +void CompileUnit::noteLocationAttribute(DIEInteger *Attr, int64_t PcOffset) { + LocationAttributes.emplace_back(Attr, PcOffset); +} + +/// \brief Add a name accelerator entry for \p Die with \p Name +/// which is stored in the string table at \p Offset. +void CompileUnit::addNameAccelerator(const DIE *Die, const char *Name, + uint32_t Offset, bool SkipPubSection) { + Pubnames.emplace_back(Name, Die, Offset, SkipPubSection); +} + +/// \brief Add a type accelerator entry for \p Die with \p Name +/// which is stored in the string table at \p Offset. +void CompileUnit::addTypeAccelerator(const DIE *Die, const char *Name, + uint32_t Offset) { + Pubtypes.emplace_back(Name, Die, Offset, false); +} + +/// \brief A string table that doesn't need relocations. +/// +/// We are doing a final link, no need for a string table that +/// has relocation entries for every reference to it. This class +/// provides this ablitity by just associating offsets with +/// strings. +class NonRelocatableStringpool { +public: + /// \brief Entries are stored into the StringMap and simply linked + /// together through the second element of this pair in order to + /// keep track of insertion order. + typedef StringMap<std::pair<uint32_t, StringMapEntryBase *>, BumpPtrAllocator> + MapTy; + + NonRelocatableStringpool() + : CurrentEndOffset(0), Sentinel(0), Last(&Sentinel) { + // Legacy dsymutil puts an empty string at the start of the line + // table. + getStringOffset(""); + } + + /// \brief Get the offset of string \p S in the string table. This + /// can insert a new element or return the offset of a preexisitng + /// one. + uint32_t getStringOffset(StringRef S); + + /// \brief Get permanent storage for \p S (but do not necessarily + /// emit \p S in the output section). + /// \returns The StringRef that points to permanent storage to use + /// in place of \p S. + StringRef internString(StringRef S); + + // \brief Return the first entry of the string table. + const MapTy::MapEntryTy *getFirstEntry() const { + return getNextEntry(&Sentinel); + } + + // \brief Get the entry following \p E in the string table or null + // if \p E was the last entry. + const MapTy::MapEntryTy *getNextEntry(const MapTy::MapEntryTy *E) const { + return static_cast<const MapTy::MapEntryTy *>(E->getValue().second); + } + + uint64_t getSize() { return CurrentEndOffset; } + +private: + MapTy Strings; + uint32_t CurrentEndOffset; + MapTy::MapEntryTy Sentinel, *Last; +}; + +/// \brief Get the offset of string \p S in the string table. This +/// can insert a new element or return the offset of a preexisitng +/// one. +uint32_t NonRelocatableStringpool::getStringOffset(StringRef S) { + if (S.empty() && !Strings.empty()) + return 0; + + std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr); + MapTy::iterator It; + bool Inserted; + + // A non-empty string can't be at offset 0, so if we have an entry + // with a 0 offset, it must be a previously interned string. + std::tie(It, Inserted) = Strings.insert(std::make_pair(S, Entry)); + if (Inserted || It->getValue().first == 0) { + // Set offset and chain at the end of the entries list. + It->getValue().first = CurrentEndOffset; + CurrentEndOffset += S.size() + 1; // +1 for the '\0'. + Last->getValue().second = &*It; + Last = &*It; + } + return It->getValue().first; +} + +/// \brief Put \p S into the StringMap so that it gets permanent +/// storage, but do not actually link it in the chain of elements +/// that go into the output section. A latter call to +/// getStringOffset() with the same string will chain it though. +StringRef NonRelocatableStringpool::internString(StringRef S) { + std::pair<uint32_t, StringMapEntryBase *> Entry(0, nullptr); + auto InsertResult = Strings.insert(std::make_pair(S, Entry)); + return InsertResult.first->getKey(); +} + +/// \brief The Dwarf streaming logic +/// +/// All interactions with the MC layer that is used to build the debug +/// information binary representation are handled in this class. +class DwarfStreamer { + /// \defgroup MCObjects MC layer objects constructed by the streamer + /// @{ + std::unique_ptr<MCRegisterInfo> MRI; + std::unique_ptr<MCAsmInfo> MAI; + std::unique_ptr<MCObjectFileInfo> MOFI; + std::unique_ptr<MCContext> MC; + MCAsmBackend *MAB; // Owned by MCStreamer + std::unique_ptr<MCInstrInfo> MII; + std::unique_ptr<MCSubtargetInfo> MSTI; + MCCodeEmitter *MCE; // Owned by MCStreamer + MCStreamer *MS; // Owned by AsmPrinter + std::unique_ptr<TargetMachine> TM; + std::unique_ptr<AsmPrinter> Asm; + /// @} + + /// \brief the file we stream the linked Dwarf to. + std::unique_ptr<raw_fd_ostream> OutFile; + + uint32_t RangesSectionSize; + uint32_t LocSectionSize; + uint32_t LineSectionSize; + + /// \brief Emit the pubnames or pubtypes section contribution for \p + /// Unit into \p Sec. The data is provided in \p Names. + void emitPubSectionForUnit(const MCSection *Sec, StringRef Name, + const CompileUnit &Unit, + const std::vector<CompileUnit::AccelInfo> &Names); + +public: + /// \brief Actually create the streamer and the ouptut file. + /// + /// This could be done directly in the constructor, but it feels + /// more natural to handle errors through return value. + bool init(Triple TheTriple, StringRef OutputFilename); + + /// \brief Dump the file to the disk. + bool finish(); + + AsmPrinter &getAsmPrinter() const { return *Asm; } + + /// \brief Set the current output section to debug_info and change + /// the MC Dwarf version to \p DwarfVersion. + void switchToDebugInfoSection(unsigned DwarfVersion); + + /// \brief Emit the compilation unit header for \p Unit in the + /// debug_info section. + /// + /// As a side effect, this also switches the current Dwarf version + /// of the MC layer to the one of U.getOrigUnit(). + void emitCompileUnitHeader(CompileUnit &Unit); + + /// \brief Recursively emit the DIE tree rooted at \p Die. + void emitDIE(DIE &Die); + + /// \brief Emit the abbreviation table \p Abbrevs to the + /// debug_abbrev section. + void emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs); + + /// \brief Emit the string table described by \p Pool. + void emitStrings(const NonRelocatableStringpool &Pool); + + /// \brief Emit debug_ranges for \p FuncRange by translating the + /// original \p Entries. + void emitRangesEntries( + int64_t UnitPcOffset, uint64_t OrigLowPc, + FunctionIntervals::const_iterator FuncRange, + const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries, + unsigned AddressSize); + + /// \brief Emit debug_aranges entries for \p Unit and if \p + /// DoRangesSection is true, also emit the debug_ranges entries for + /// the DW_TAG_compile_unit's DW_AT_ranges attribute. + void emitUnitRangesEntries(CompileUnit &Unit, bool DoRangesSection); + + uint32_t getRangesSectionSize() const { return RangesSectionSize; } + + /// \brief Emit the debug_loc contribution for \p Unit by copying + /// the entries from \p Dwarf and offseting them. Update the + /// location attributes to point to the new entries. + void emitLocationsForUnit(const CompileUnit &Unit, DWARFContext &Dwarf); + + /// \brief Emit the line table described in \p Rows into the + /// debug_line section. + void emitLineTableForUnit(StringRef PrologueBytes, unsigned MinInstLength, + std::vector<DWARFDebugLine::Row> &Rows, + unsigned AdddressSize); + + uint32_t getLineSectionSize() const { return LineSectionSize; } + + /// \brief Emit the .debug_pubnames contribution for \p Unit. + void emitPubNamesForUnit(const CompileUnit &Unit); + + /// \brief Emit the .debug_pubtypes contribution for \p Unit. + void emitPubTypesForUnit(const CompileUnit &Unit); }; +bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) { + std::string ErrorStr; + std::string TripleName; + StringRef Context = "dwarf streamer init"; + + // Get the target. + const Target *TheTarget = + TargetRegistry::lookupTarget(TripleName, TheTriple, ErrorStr); + if (!TheTarget) + return error(ErrorStr, Context); + TripleName = TheTriple.getTriple(); + + // Create all the MC Objects. + MRI.reset(TheTarget->createMCRegInfo(TripleName)); + if (!MRI) + return error(Twine("no register info for target ") + TripleName, Context); + + MAI.reset(TheTarget->createMCAsmInfo(*MRI, TripleName)); + if (!MAI) + return error("no asm info for target " + TripleName, Context); + + MOFI.reset(new MCObjectFileInfo); + MC.reset(new MCContext(MAI.get(), MRI.get(), MOFI.get())); + MOFI->InitMCObjectFileInfo(TripleName, Reloc::Default, CodeModel::Default, + *MC); + + MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, ""); + if (!MAB) + return error("no asm backend for target " + TripleName, Context); + + MII.reset(TheTarget->createMCInstrInfo()); + if (!MII) + return error("no instr info info for target " + TripleName, Context); + + MSTI.reset(TheTarget->createMCSubtargetInfo(TripleName, "", "")); + if (!MSTI) + return error("no subtarget info for target " + TripleName, Context); + + MCE = TheTarget->createMCCodeEmitter(*MII, *MRI, *MC); + if (!MCE) + return error("no code emitter for target " + TripleName, Context); + + // Create the output file. + std::error_code EC; + OutFile = + llvm::make_unique<raw_fd_ostream>(OutputFilename, EC, sys::fs::F_None); + if (EC) + return error(Twine(OutputFilename) + ": " + EC.message(), Context); + + MS = TheTarget->createMCObjectStreamer(TheTriple, *MC, *MAB, *OutFile, MCE, + *MSTI, false, + /*DWARFMustBeAtTheEnd*/ false); + if (!MS) + return error("no object streamer for target " + TripleName, Context); + + // Finally create the AsmPrinter we'll use to emit the DIEs. + TM.reset(TheTarget->createTargetMachine(TripleName, "", "", TargetOptions())); + if (!TM) + return error("no target machine for target " + TripleName, Context); + + Asm.reset(TheTarget->createAsmPrinter(*TM, std::unique_ptr<MCStreamer>(MS))); + if (!Asm) + return error("no asm printer for target " + TripleName, Context); + + RangesSectionSize = 0; + LocSectionSize = 0; + LineSectionSize = 0; + + return true; +} + +bool DwarfStreamer::finish() { + MS->Finish(); + return true; +} + +/// \brief Set the current output section to debug_info and change +/// the MC Dwarf version to \p DwarfVersion. +void DwarfStreamer::switchToDebugInfoSection(unsigned DwarfVersion) { + MS->SwitchSection(MOFI->getDwarfInfoSection()); + MC->setDwarfVersion(DwarfVersion); +} + +/// \brief Emit the compilation unit header for \p Unit in the +/// debug_info section. +/// +/// A Dwarf scetion header is encoded as: +/// uint32_t Unit length (omiting this field) +/// uint16_t Version +/// uint32_t Abbreviation table offset +/// uint8_t Address size +/// +/// Leading to a total of 11 bytes. +void DwarfStreamer::emitCompileUnitHeader(CompileUnit &Unit) { + unsigned Version = Unit.getOrigUnit().getVersion(); + switchToDebugInfoSection(Version); + + // Emit size of content not including length itself. The size has + // already been computed in CompileUnit::computeOffsets(). Substract + // 4 to that size to account for the length field. + Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset() - 4); + Asm->EmitInt16(Version); + // We share one abbreviations table across all units so it's always at the + // start of the section. + Asm->EmitInt32(0); + Asm->EmitInt8(Unit.getOrigUnit().getAddressByteSize()); +} + +/// \brief Emit the \p Abbrevs array as the shared abbreviation table +/// for the linked Dwarf file. +void DwarfStreamer::emitAbbrevs(const std::vector<DIEAbbrev *> &Abbrevs) { + MS->SwitchSection(MOFI->getDwarfAbbrevSection()); + Asm->emitDwarfAbbrevs(Abbrevs); +} + +/// \brief Recursively emit the DIE tree rooted at \p Die. +void DwarfStreamer::emitDIE(DIE &Die) { + MS->SwitchSection(MOFI->getDwarfInfoSection()); + Asm->emitDwarfDIE(Die); +} + +/// \brief Emit the debug_str section stored in \p Pool. +void DwarfStreamer::emitStrings(const NonRelocatableStringpool &Pool) { + Asm->OutStreamer.SwitchSection(MOFI->getDwarfStrSection()); + for (auto *Entry = Pool.getFirstEntry(); Entry; + Entry = Pool.getNextEntry(Entry)) + Asm->OutStreamer.EmitBytes( + StringRef(Entry->getKey().data(), Entry->getKey().size() + 1)); +} + +/// \brief Emit the debug_range section contents for \p FuncRange by +/// translating the original \p Entries. The debug_range section +/// format is totally trivial, consisting just of pairs of address +/// sized addresses describing the ranges. +void DwarfStreamer::emitRangesEntries( + int64_t UnitPcOffset, uint64_t OrigLowPc, + FunctionIntervals::const_iterator FuncRange, + const std::vector<DWARFDebugRangeList::RangeListEntry> &Entries, + unsigned AddressSize) { + MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection()); + + // Offset each range by the right amount. + int64_t PcOffset = FuncRange.value() + UnitPcOffset; + for (const auto &Range : Entries) { + if (Range.isBaseAddressSelectionEntry(AddressSize)) { + warn("unsupported base address selection operation", + "emitting debug_ranges"); + break; + } + // Do not emit empty ranges. + if (Range.StartAddress == Range.EndAddress) + continue; + + // All range entries should lie in the function range. + if (!(Range.StartAddress + OrigLowPc >= FuncRange.start() && + Range.EndAddress + OrigLowPc <= FuncRange.stop())) + warn("inconsistent range data.", "emitting debug_ranges"); + MS->EmitIntValue(Range.StartAddress + PcOffset, AddressSize); + MS->EmitIntValue(Range.EndAddress + PcOffset, AddressSize); + RangesSectionSize += 2 * AddressSize; + } + + // Add the terminator entry. + MS->EmitIntValue(0, AddressSize); + MS->EmitIntValue(0, AddressSize); + RangesSectionSize += 2 * AddressSize; +} + +/// \brief Emit the debug_aranges contribution of a unit and +/// if \p DoDebugRanges is true the debug_range contents for a +/// compile_unit level DW_AT_ranges attribute (Which are basically the +/// same thing with a different base address). +/// Just aggregate all the ranges gathered inside that unit. +void DwarfStreamer::emitUnitRangesEntries(CompileUnit &Unit, + bool DoDebugRanges) { + unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize(); + // Gather the ranges in a vector, so that we can simplify them. The + // IntervalMap will have coalesced the non-linked ranges, but here + // we want to coalesce the linked addresses. + std::vector<std::pair<uint64_t, uint64_t>> Ranges; + const auto &FunctionRanges = Unit.getFunctionRanges(); + for (auto Range = FunctionRanges.begin(), End = FunctionRanges.end(); + Range != End; ++Range) + Ranges.push_back(std::make_pair(Range.start() + Range.value(), + Range.stop() + Range.value())); + + // The object addresses where sorted, but again, the linked + // addresses might end up in a different order. + std::sort(Ranges.begin(), Ranges.end()); + + if (!Ranges.empty()) { + MS->SwitchSection(MC->getObjectFileInfo()->getDwarfARangesSection()); + + MCSymbol *BeginLabel = Asm->createTempSymbol("Barange"); + MCSymbol *EndLabel = Asm->createTempSymbol("Earange"); + + unsigned HeaderSize = + sizeof(int32_t) + // Size of contents (w/o this field + sizeof(int16_t) + // DWARF ARange version number + sizeof(int32_t) + // Offset of CU in the .debug_info section + sizeof(int8_t) + // Pointer Size (in bytes) + sizeof(int8_t); // Segment Size (in bytes) + + unsigned TupleSize = AddressSize * 2; + unsigned Padding = OffsetToAlignment(HeaderSize, TupleSize); + + Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Arange length + Asm->OutStreamer.EmitLabel(BeginLabel); + Asm->EmitInt16(dwarf::DW_ARANGES_VERSION); // Version number + Asm->EmitInt32(Unit.getStartOffset()); // Corresponding unit's offset + Asm->EmitInt8(AddressSize); // Address size + Asm->EmitInt8(0); // Segment size + + Asm->OutStreamer.EmitFill(Padding, 0x0); + + for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; + ++Range) { + uint64_t RangeStart = Range->first; + MS->EmitIntValue(RangeStart, AddressSize); + while ((Range + 1) != End && Range->second == (Range + 1)->first) + ++Range; + MS->EmitIntValue(Range->second - RangeStart, AddressSize); + } + + // Emit terminator + Asm->OutStreamer.EmitIntValue(0, AddressSize); + Asm->OutStreamer.EmitIntValue(0, AddressSize); + Asm->OutStreamer.EmitLabel(EndLabel); + } + + if (!DoDebugRanges) + return; + + MS->SwitchSection(MC->getObjectFileInfo()->getDwarfRangesSection()); + // Offset each range by the right amount. + int64_t PcOffset = -Unit.getLowPc(); + // Emit coalesced ranges. + for (auto Range = Ranges.begin(), End = Ranges.end(); Range != End; ++Range) { + MS->EmitIntValue(Range->first + PcOffset, AddressSize); + while (Range + 1 != End && Range->second == (Range + 1)->first) + ++Range; + MS->EmitIntValue(Range->second + PcOffset, AddressSize); + RangesSectionSize += 2 * AddressSize; + } + + // Add the terminator entry. + MS->EmitIntValue(0, AddressSize); + MS->EmitIntValue(0, AddressSize); + RangesSectionSize += 2 * AddressSize; +} + +/// \brief Emit location lists for \p Unit and update attribtues to +/// point to the new entries. +void DwarfStreamer::emitLocationsForUnit(const CompileUnit &Unit, + DWARFContext &Dwarf) { + const std::vector<std::pair<DIEInteger *, int64_t>> &Attributes = + Unit.getLocationAttributes(); + + if (Attributes.empty()) + return; + + MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLocSection()); + + unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize(); + const DWARFSection &InputSec = Dwarf.getLocSection(); + DataExtractor Data(InputSec.Data, Dwarf.isLittleEndian(), AddressSize); + DWARFUnit &OrigUnit = Unit.getOrigUnit(); + const auto *OrigUnitDie = OrigUnit.getCompileUnitDIE(false); + int64_t UnitPcOffset = 0; + uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress( + &OrigUnit, dwarf::DW_AT_low_pc, -1ULL); + if (OrigLowPc != -1ULL) + UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc(); + + for (const auto &Attr : Attributes) { + uint32_t Offset = Attr.first->getValue(); + Attr.first->setValue(LocSectionSize); + // This is the quantity to add to the old location address to get + // the correct address for the new one. + int64_t LocPcOffset = Attr.second + UnitPcOffset; + while (Data.isValidOffset(Offset)) { + uint64_t Low = Data.getUnsigned(&Offset, AddressSize); + uint64_t High = Data.getUnsigned(&Offset, AddressSize); + LocSectionSize += 2 * AddressSize; + if (Low == 0 && High == 0) { + Asm->OutStreamer.EmitIntValue(0, AddressSize); + Asm->OutStreamer.EmitIntValue(0, AddressSize); + break; + } + Asm->OutStreamer.EmitIntValue(Low + LocPcOffset, AddressSize); + Asm->OutStreamer.EmitIntValue(High + LocPcOffset, AddressSize); + uint64_t Length = Data.getU16(&Offset); + Asm->OutStreamer.EmitIntValue(Length, 2); + // Just copy the bytes over. + Asm->OutStreamer.EmitBytes( + StringRef(InputSec.Data.substr(Offset, Length))); + Offset += Length; + LocSectionSize += Length + 2; + } + } +} + +void DwarfStreamer::emitLineTableForUnit(StringRef PrologueBytes, + unsigned MinInstLength, + std::vector<DWARFDebugLine::Row> &Rows, + unsigned PointerSize) { + // Switch to the section where the table will be emitted into. + MS->SwitchSection(MC->getObjectFileInfo()->getDwarfLineSection()); + MCSymbol *LineStartSym = MC->CreateTempSymbol(); + MCSymbol *LineEndSym = MC->CreateTempSymbol(); + + // The first 4 bytes is the total length of the information for this + // compilation unit (not including these 4 bytes for the length). + Asm->EmitLabelDifference(LineEndSym, LineStartSym, 4); + Asm->OutStreamer.EmitLabel(LineStartSym); + // Copy Prologue. + MS->EmitBytes(PrologueBytes); + LineSectionSize += PrologueBytes.size() + 4; + + SmallString<128> EncodingBuffer; + raw_svector_ostream EncodingOS(EncodingBuffer); + + if (Rows.empty()) { + // We only have the dummy entry, dsymutil emits an entry with a 0 + // address in that case. + MCDwarfLineAddr::Encode(*MC, INT64_MAX, 0, EncodingOS); + MS->EmitBytes(EncodingOS.str()); + LineSectionSize += EncodingBuffer.size(); + MS->EmitLabel(LineEndSym); + return; + } + + // Line table state machine fields + unsigned FileNum = 1; + unsigned LastLine = 1; + unsigned Column = 0; + unsigned IsStatement = 1; + unsigned Isa = 0; + uint64_t Address = -1ULL; + + unsigned RowsSinceLastSequence = 0; + + for (unsigned Idx = 0; Idx < Rows.size(); ++Idx) { + auto &Row = Rows[Idx]; + + int64_t AddressDelta; + if (Address == -1ULL) { + MS->EmitIntValue(dwarf::DW_LNS_extended_op, 1); + MS->EmitULEB128IntValue(PointerSize + 1); + MS->EmitIntValue(dwarf::DW_LNE_set_address, 1); + MS->EmitIntValue(Row.Address, PointerSize); + LineSectionSize += 2 + PointerSize + getULEB128Size(PointerSize + 1); + AddressDelta = 0; + } else { + AddressDelta = (Row.Address - Address) / MinInstLength; + } + + // FIXME: code copied and transfromed from + // MCDwarf.cpp::EmitDwarfLineTable. We should find a way to share + // this code, but the current compatibility requirement with + // classic dsymutil makes it hard. Revisit that once this + // requirement is dropped. + + if (FileNum != Row.File) { + FileNum = Row.File; + MS->EmitIntValue(dwarf::DW_LNS_set_file, 1); + MS->EmitULEB128IntValue(FileNum); + LineSectionSize += 1 + getULEB128Size(FileNum); + } + if (Column != Row.Column) { + Column = Row.Column; + MS->EmitIntValue(dwarf::DW_LNS_set_column, 1); + MS->EmitULEB128IntValue(Column); + LineSectionSize += 1 + getULEB128Size(Column); + } + + // FIXME: We should handle the discriminator here, but dsymutil + // doesn' consider it, thus ignore it for now. + + if (Isa != Row.Isa) { + Isa = Row.Isa; + MS->EmitIntValue(dwarf::DW_LNS_set_isa, 1); + MS->EmitULEB128IntValue(Isa); + LineSectionSize += 1 + getULEB128Size(Isa); + } + if (IsStatement != Row.IsStmt) { + IsStatement = Row.IsStmt; + MS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1); + LineSectionSize += 1; + } + if (Row.BasicBlock) { + MS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1); + LineSectionSize += 1; + } + + if (Row.PrologueEnd) { + MS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1); + LineSectionSize += 1; + } + + if (Row.EpilogueBegin) { + MS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1); + LineSectionSize += 1; + } + + int64_t LineDelta = int64_t(Row.Line) - LastLine; + if (!Row.EndSequence) { + MCDwarfLineAddr::Encode(*MC, LineDelta, AddressDelta, EncodingOS); + MS->EmitBytes(EncodingOS.str()); + LineSectionSize += EncodingBuffer.size(); + EncodingBuffer.resize(0); + EncodingOS.resync(); + Address = Row.Address; + LastLine = Row.Line; + RowsSinceLastSequence++; + } else { + if (LineDelta) { + MS->EmitIntValue(dwarf::DW_LNS_advance_line, 1); + MS->EmitSLEB128IntValue(LineDelta); + LineSectionSize += 1 + getSLEB128Size(LineDelta); + } + if (AddressDelta) { + MS->EmitIntValue(dwarf::DW_LNS_advance_pc, 1); + MS->EmitULEB128IntValue(AddressDelta); + LineSectionSize += 1 + getULEB128Size(AddressDelta); + } + MCDwarfLineAddr::Encode(*MC, INT64_MAX, 0, EncodingOS); + MS->EmitBytes(EncodingOS.str()); + LineSectionSize += EncodingBuffer.size(); + EncodingBuffer.resize(0); + EncodingOS.resync(); + Address = -1ULL; + LastLine = FileNum = IsStatement = 1; + RowsSinceLastSequence = Column = Isa = 0; + } + } + + if (RowsSinceLastSequence) { + MCDwarfLineAddr::Encode(*MC, INT64_MAX, 0, EncodingOS); + MS->EmitBytes(EncodingOS.str()); + LineSectionSize += EncodingBuffer.size(); + EncodingBuffer.resize(0); + EncodingOS.resync(); + } + + MS->EmitLabel(LineEndSym); +} + +/// \brief Emit the pubnames or pubtypes section contribution for \p +/// Unit into \p Sec. The data is provided in \p Names. +void DwarfStreamer::emitPubSectionForUnit( + const MCSection *Sec, StringRef SecName, const CompileUnit &Unit, + const std::vector<CompileUnit::AccelInfo> &Names) { + if (Names.empty()) + return; + + // Start the dwarf pubnames section. + Asm->OutStreamer.SwitchSection(Sec); + MCSymbol *BeginLabel = Asm->createTempSymbol("pub" + SecName + "_begin"); + MCSymbol *EndLabel = Asm->createTempSymbol("pub" + SecName + "_end"); + + bool HeaderEmitted = false; + // Emit the pubnames for this compilation unit. + for (const auto &Name : Names) { + if (Name.SkipPubSection) + continue; + + if (!HeaderEmitted) { + // Emit the header. + Asm->EmitLabelDifference(EndLabel, BeginLabel, 4); // Length + Asm->OutStreamer.EmitLabel(BeginLabel); + Asm->EmitInt16(dwarf::DW_PUBNAMES_VERSION); // Version + Asm->EmitInt32(Unit.getStartOffset()); // Unit offset + Asm->EmitInt32(Unit.getNextUnitOffset() - Unit.getStartOffset()); // Size + HeaderEmitted = true; + } + Asm->EmitInt32(Name.Die->getOffset()); + Asm->OutStreamer.EmitBytes( + StringRef(Name.Name.data(), Name.Name.size() + 1)); + } + + if (!HeaderEmitted) + return; + Asm->EmitInt32(0); // End marker. + Asm->OutStreamer.EmitLabel(EndLabel); +} + +/// \brief Emit .debug_pubnames for \p Unit. +void DwarfStreamer::emitPubNamesForUnit(const CompileUnit &Unit) { + emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubNamesSection(), + "names", Unit, Unit.getPubnames()); +} + +/// \brief Emit .debug_pubtypes for \p Unit. +void DwarfStreamer::emitPubTypesForUnit(const CompileUnit &Unit) { + emitPubSectionForUnit(MC->getObjectFileInfo()->getDwarfPubTypesSection(), + "types", Unit, Unit.getPubtypes()); +} + /// \brief The core of the Dwarf linking logic. /// /// The link of the dwarf information from the object files will be @@ -66,15 +976,21 @@ private: /// first step when we start processing a DebugMapObject. class DwarfLinker { public: - DwarfLinker(StringRef OutputFilename, bool Verbose) - : OutputFilename(OutputFilename), Verbose(Verbose), BinHolder(Verbose) {} + DwarfLinker(StringRef OutputFilename, const LinkOptions &Options) + : OutputFilename(OutputFilename), Options(Options), + BinHolder(Options.Verbose) {} + + ~DwarfLinker() { + for (auto *Abbrev : Abbreviations) + delete Abbrev; + } /// \brief Link the contents of the DebugMap. bool link(const DebugMap &); private: /// \brief Called at the start of a debug object link. - void startDebugObject(DWARFContext &); + void startDebugObject(DWARFContext &, DebugMapObject &); /// \brief Called at the end of a debug object link. void endDebugObject(); @@ -104,7 +1020,7 @@ private: /// consider. As we walk the DIEs in acsending file offset and as /// ValidRelocs is sorted by file offset, keeping this index /// uptodate is all we have to do to have a cheap lookup during the - /// root DIE selection. + /// root DIE selection and during DIE cloning. unsigned NextValidReloc; bool findValidRelocsInDebugInfo(const object::ObjectFile &Obj, @@ -160,6 +1076,114 @@ private: CompileUnit::DIEInfo &Info); /// @} + /// \defgroup Linking Methods used to link the debug information + /// + /// @{ + /// \brief Recursively clone \p InputDIE into an tree of DIE objects + /// where useless (as decided by lookForDIEsToKeep()) bits have been + /// stripped out and addresses have been rewritten according to the + /// debug map. + /// + /// \param OutOffset is the offset the cloned DIE in the output + /// compile unit. + /// \param PCOffset (while cloning a function scope) is the offset + /// applied to the entry point of the function to get the linked address. + /// + /// \returns the root of the cloned tree. + DIE *cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &U, + int64_t PCOffset, uint32_t OutOffset); + + typedef DWARFAbbreviationDeclaration::AttributeSpec AttributeSpec; + + /// \brief Information gathered and exchanged between the various + /// clone*Attributes helpers about the attributes of a particular DIE. + struct AttributesInfo { + const char *Name, *MangledName; ///< Names. + uint32_t NameOffset, MangledNameOffset; ///< Offsets in the string pool. + + uint64_t OrigHighPc; ///< Value of AT_high_pc in the input DIE + int64_t PCOffset; ///< Offset to apply to PC addresses inside a function. + + bool HasLowPc; ///< Does the DIE have a low_pc attribute? + bool IsDeclaration; ///< Is this DIE only a declaration? + + AttributesInfo() + : Name(nullptr), MangledName(nullptr), NameOffset(0), + MangledNameOffset(0), OrigHighPc(0), PCOffset(0), HasLowPc(false), + IsDeclaration(false) {} + }; + + /// \brief Helper for cloneDIE. + unsigned cloneAttribute(DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, + CompileUnit &U, const DWARFFormValue &Val, + const AttributeSpec AttrSpec, unsigned AttrSize, + AttributesInfo &AttrInfo); + + /// \brief Helper for cloneDIE. + unsigned cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec, + const DWARFFormValue &Val, const DWARFUnit &U); + + /// \brief Helper for cloneDIE. + unsigned + cloneDieReferenceAttribute(DIE &Die, + const DWARFDebugInfoEntryMinimal &InputDIE, + AttributeSpec AttrSpec, unsigned AttrSize, + const DWARFFormValue &Val, CompileUnit &Unit); + + /// \brief Helper for cloneDIE. + unsigned cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec, + const DWARFFormValue &Val, unsigned AttrSize); + + /// \brief Helper for cloneDIE. + unsigned cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec, + const DWARFFormValue &Val, + const CompileUnit &Unit, AttributesInfo &Info); + + /// \brief Helper for cloneDIE. + unsigned cloneScalarAttribute(DIE &Die, + const DWARFDebugInfoEntryMinimal &InputDIE, + CompileUnit &U, AttributeSpec AttrSpec, + const DWARFFormValue &Val, unsigned AttrSize, + AttributesInfo &Info); + + /// \brief Helper for cloneDIE. + bool applyValidRelocs(MutableArrayRef<char> Data, uint32_t BaseOffset, + bool isLittleEndian); + + /// \brief Assign an abbreviation number to \p Abbrev + void AssignAbbrev(DIEAbbrev &Abbrev); + + /// \brief FoldingSet that uniques the abbreviations. + FoldingSet<DIEAbbrev> AbbreviationsSet; + /// \brief Storage for the unique Abbreviations. + /// This is passed to AsmPrinter::emitDwarfAbbrevs(), thus it cannot + /// be changed to a vecot of unique_ptrs. + std::vector<DIEAbbrev *> Abbreviations; + + /// \brief Compute and emit debug_ranges section for \p Unit, and + /// patch the attributes referencing it. + void patchRangesForUnit(const CompileUnit &Unit, DWARFContext &Dwarf) const; + + /// \brief Generate and emit the DW_AT_ranges attribute for a + /// compile_unit if it had one. + void generateUnitRanges(CompileUnit &Unit) const; + + /// \brief Extract the line tables fromt he original dwarf, extract + /// the relevant parts according to the linked function ranges and + /// emit the result in the debug_line section. + void patchLineTableForUnit(CompileUnit &Unit, DWARFContext &OrigDwarf); + + /// \brief Emit the accelerator entries for \p Unit. + void emitAcceleratorEntriesForUnit(CompileUnit &Unit); + + /// \brief DIELoc objects that need to be destructed (but not freed!). + std::vector<DIELoc *> DIELocs; + /// \brief DIEBlock objects that need to be destructed (but not freed!). + std::vector<DIEBlock *> DIEBlocks; + /// \brief Allocator used for all the DIEValue objects. + BumpPtrAllocator DIEAlloc; + /// @} + /// \defgroup Helpers Various helper methods. /// /// @{ @@ -170,20 +1194,37 @@ private: CompileUnit *getUnitForOffset(unsigned Offset); + bool getDIENames(const DWARFDebugInfoEntryMinimal &Die, DWARFUnit &U, + AttributesInfo &Info); + void reportWarning(const Twine &Warning, const DWARFUnit *Unit = nullptr, - const DWARFDebugInfoEntryMinimal *DIE = nullptr); + const DWARFDebugInfoEntryMinimal *DIE = nullptr) const; + + bool createStreamer(Triple TheTriple, StringRef OutputFilename); /// @} private: std::string OutputFilename; - bool Verbose; + LinkOptions Options; BinaryHolder BinHolder; + std::unique_ptr<DwarfStreamer> Streamer; /// The units of the current debug map object. std::vector<CompileUnit> Units; /// The debug map object curently under consideration. DebugMapObject *CurrentDebugObject; + + /// \brief The Dwarf string pool + NonRelocatableStringpool StringPool; + + /// \brief This map is keyed by the entry PC of functions in that + /// debug object and the associated value is a pair storing the + /// corresponding end PC and the offset to apply to get the linked + /// address. + /// + /// See startDebugObject() for a more complete description of its use. + std::map<uint64_t, std::pair<uint64_t, int64_t>> Ranges; }; /// \brief Similar to DWARFUnitSection::getUnitForOffset(), but @@ -215,16 +1256,34 @@ const DWARFDebugInfoEntryMinimal *DwarfLinker::resolveDIEReference( return nullptr; } +/// \brief Get the potential name and mangled name for the entity +/// described by \p Die and store them in \Info if they are not +/// already there. +/// \returns is a name was found. +bool DwarfLinker::getDIENames(const DWARFDebugInfoEntryMinimal &Die, + DWARFUnit &U, AttributesInfo &Info) { + // FIXME: a bit wastefull as the first getName might return the + // short name. + if (!Info.MangledName && + (Info.MangledName = Die.getName(&U, DINameKind::LinkageName))) + Info.MangledNameOffset = StringPool.getStringOffset(Info.MangledName); + + if (!Info.Name && (Info.Name = Die.getName(&U, DINameKind::ShortName))) + Info.NameOffset = StringPool.getStringOffset(Info.Name); + + return Info.Name || Info.MangledName; +} + /// \brief Report a warning to the user, optionaly including /// information about a specific \p DIE related to the warning. void DwarfLinker::reportWarning(const Twine &Warning, const DWARFUnit *Unit, - const DWARFDebugInfoEntryMinimal *DIE) { + const DWARFDebugInfoEntryMinimal *DIE) const { + StringRef Context = "<debug map>"; if (CurrentDebugObject) - errs() << Twine("while processing ") + - CurrentDebugObject->getObjectFilename() + ":\n"; - errs() << Twine("warning: ") + Warning + "\n"; + Context = CurrentDebugObject->getObjectFilename(); + warn(Warning, Context); - if (!Verbose || !DIE) + if (!Options.Verbose || !DIE) return; errs() << " in DIE:\n"; @@ -232,6 +1291,14 @@ void DwarfLinker::reportWarning(const Twine &Warning, const DWARFUnit *Unit, 6 /* Indent */); } +bool DwarfLinker::createStreamer(Triple TheTriple, StringRef OutputFilename) { + if (Options.NoOutput) + return true; + + Streamer = llvm::make_unique<DwarfStreamer>(); + return Streamer->init(TheTriple, OutputFilename); +} + /// \brief Recursive helper to gather the child->parent relationships in the /// original compile unit. static void gatherDIEParents(const DWARFDebugInfoEntryMinimal *DIE, @@ -260,14 +1327,45 @@ static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) { llvm_unreachable("Invalid Tag"); } -void DwarfLinker::startDebugObject(DWARFContext &Dwarf) { +void DwarfLinker::startDebugObject(DWARFContext &Dwarf, DebugMapObject &Obj) { Units.reserve(Dwarf.getNumCompileUnits()); NextValidReloc = 0; + // Iterate over the debug map entries and put all the ones that are + // functions (because they have a size) into the Ranges map. This + // map is very similar to the FunctionRanges that are stored in each + // unit, with 2 notable differences: + // - obviously this one is global, while the other ones are per-unit. + // - this one contains not only the functions described in the DIE + // tree, but also the ones that are only in the debug map. + // The latter information is required to reproduce dsymutil's logic + // while linking line tables. The cases where this information + // matters look like bugs that need to be investigated, but for now + // we need to reproduce dsymutil's behavior. + // FIXME: Once we understood exactly if that information is needed, + // maybe totally remove this (or try to use it to do a real + // -gline-tables-only on Darwin. + for (const auto &Entry : Obj.symbols()) { + const auto &Mapping = Entry.getValue(); + if (Mapping.Size) + Ranges[Mapping.ObjectAddress] = std::make_pair( + Mapping.ObjectAddress + Mapping.Size, + int64_t(Mapping.BinaryAddress) - Mapping.ObjectAddress); + } } void DwarfLinker::endDebugObject() { Units.clear(); ValidRelocs.clear(); + Ranges.clear(); + + for (auto *Block : DIEBlocks) + Block->~DIEBlock(); + for (auto *Loc : DIELocs) + Loc->~DIELoc(); + + DIEBlocks.clear(); + DIELocs.clear(); + DIEAlloc.Reset(); } /// \brief Iterate over the relocations of the given \p Section and @@ -378,14 +1476,15 @@ bool DwarfLinker::hasValidRelocation(uint32_t StartOffset, uint32_t EndOffset, return false; const auto &ValidReloc = ValidRelocs[NextValidReloc++]; - if (Verbose) + if (Options.Verbose) outs() << "Found valid debug map entry: " << ValidReloc.Mapping->getKey() << " " << format("\t%016" PRIx64 " => %016" PRIx64, ValidReloc.Mapping->getValue().ObjectAddress, ValidReloc.Mapping->getValue().BinaryAddress); - Info.Address = - ValidReloc.Mapping->getValue().BinaryAddress + ValidReloc.Addend; + Info.AddrAdjust = int64_t(ValidReloc.Mapping->getValue().BinaryAddress) + + ValidReloc.Addend - + ValidReloc.Mapping->getValue().ObjectAddress; Info.InDebugMap = true; return true; } @@ -442,7 +1541,7 @@ unsigned DwarfLinker::shouldKeepVariableDIE( (Flags & TF_InFunctionScope)) return Flags; - if (Verbose) + if (Options.Verbose) DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */); return Flags | TF_Keep; @@ -474,10 +1573,30 @@ unsigned DwarfLinker::shouldKeepSubprogramDIE( !hasValidRelocation(LowPcOffset, LowPcEndOffset, MyInfo)) return Flags; - if (Verbose) + if (Options.Verbose) DIE.dump(outs(), const_cast<DWARFUnit *>(&OrigUnit), 0, 8 /* Indent */); - return Flags | TF_Keep; + Flags |= TF_Keep; + + DWARFFormValue HighPcValue; + if (!DIE.getAttributeValue(&OrigUnit, dwarf::DW_AT_high_pc, HighPcValue)) { + reportWarning("Function without high_pc. Range will be discarded.\n", + &OrigUnit, &DIE); + return Flags; + } + + uint64_t HighPc; + if (HighPcValue.isFormClass(DWARFFormValue::FC_Address)) { + HighPc = *HighPcValue.getAsAddress(&OrigUnit); + } else { + assert(HighPcValue.isFormClass(DWARFFormValue::FC_Constant)); + HighPc = LowPc + *HighPcValue.getAsUnsignedConstant(); + } + + // Replace the debug map range with a more accurate one. + Ranges[LowPc] = std::make_pair(HighPc, MyInfo.AddrAdjust); + Unit.addFunctionRange(LowPc, HighPc, MyInfo.AddrAdjust); + return Flags; } /// \brief Check if a DIE should be kept. @@ -503,7 +1622,6 @@ unsigned DwarfLinker::shouldKeepDIE(const DWARFDebugInfoEntryMinimal &DIE, return Flags; } - /// \brief Mark the passed DIE as well as all the ones it depends on /// as kept. /// @@ -601,6 +1719,708 @@ void DwarfLinker::lookForDIEsToKeep(const DWARFDebugInfoEntryMinimal &DIE, lookForDIEsToKeep(*Child, DMO, CU, Flags); } +/// \brief Assign an abbreviation numer to \p Abbrev. +/// +/// Our DIEs get freed after every DebugMapObject has been processed, +/// thus the FoldingSet we use to unique DIEAbbrevs cannot refer to +/// the instances hold by the DIEs. When we encounter an abbreviation +/// that we don't know, we create a permanent copy of it. +void DwarfLinker::AssignAbbrev(DIEAbbrev &Abbrev) { + // Check the set for priors. + FoldingSetNodeID ID; + Abbrev.Profile(ID); + void *InsertToken; + DIEAbbrev *InSet = AbbreviationsSet.FindNodeOrInsertPos(ID, InsertToken); + + // If it's newly added. + if (InSet) { + // Assign existing abbreviation number. + Abbrev.setNumber(InSet->getNumber()); + } else { + // Add to abbreviation list. + Abbreviations.push_back( + new DIEAbbrev(Abbrev.getTag(), Abbrev.hasChildren())); + for (const auto &Attr : Abbrev.getData()) + Abbreviations.back()->AddAttribute(Attr.getAttribute(), Attr.getForm()); + AbbreviationsSet.InsertNode(Abbreviations.back(), InsertToken); + // Assign the unique abbreviation number. + Abbrev.setNumber(Abbreviations.size()); + Abbreviations.back()->setNumber(Abbreviations.size()); + } +} + +/// \brief Clone a string attribute described by \p AttrSpec and add +/// it to \p Die. +/// \returns the size of the new attribute. +unsigned DwarfLinker::cloneStringAttribute(DIE &Die, AttributeSpec AttrSpec, + const DWARFFormValue &Val, + const DWARFUnit &U) { + // Switch everything to out of line strings. + const char *String = *Val.getAsCString(&U); + unsigned Offset = StringPool.getStringOffset(String); + Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp, + new (DIEAlloc) DIEInteger(Offset)); + return 4; +} + +/// \brief Clone an attribute referencing another DIE and add +/// it to \p Die. +/// \returns the size of the new attribute. +unsigned DwarfLinker::cloneDieReferenceAttribute( + DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, + AttributeSpec AttrSpec, unsigned AttrSize, const DWARFFormValue &Val, + CompileUnit &Unit) { + uint32_t Ref = *Val.getAsReference(&Unit.getOrigUnit()); + DIE *NewRefDie = nullptr; + CompileUnit *RefUnit = nullptr; + const DWARFDebugInfoEntryMinimal *RefDie = nullptr; + + if (!(RefUnit = getUnitForOffset(Ref)) || + !(RefDie = RefUnit->getOrigUnit().getDIEForOffset(Ref))) { + const char *AttributeString = dwarf::AttributeString(AttrSpec.Attr); + if (!AttributeString) + AttributeString = "DW_AT_???"; + reportWarning(Twine("Missing DIE for ref in attribute ") + AttributeString + + ". Dropping.", + &Unit.getOrigUnit(), &InputDIE); + return 0; + } + + unsigned Idx = RefUnit->getOrigUnit().getDIEIndex(RefDie); + CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(Idx); + if (!RefInfo.Clone) { + assert(Ref > InputDIE.getOffset()); + // We haven't cloned this DIE yet. Just create an empty one and + // store it. It'll get really cloned when we process it. + RefInfo.Clone = new DIE(dwarf::Tag(RefDie->getTag())); + } + NewRefDie = RefInfo.Clone; + + if (AttrSpec.Form == dwarf::DW_FORM_ref_addr) { + // We cannot currently rely on a DIEEntry to emit ref_addr + // references, because the implementation calls back to DwarfDebug + // to find the unit offset. (We don't have a DwarfDebug) + // FIXME: we should be able to design DIEEntry reliance on + // DwarfDebug away. + DIEInteger *Attr; + if (Ref < InputDIE.getOffset()) { + // We must have already cloned that DIE. + uint32_t NewRefOffset = + RefUnit->getStartOffset() + NewRefDie->getOffset(); + Attr = new (DIEAlloc) DIEInteger(NewRefOffset); + } else { + // A forward reference. Note and fixup later. + Attr = new (DIEAlloc) DIEInteger(0xBADDEF); + Unit.noteForwardReference(NewRefDie, RefUnit, Attr); + } + Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_ref_addr, + Attr); + return AttrSize; + } + + Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::Form(AttrSpec.Form), + new (DIEAlloc) DIEEntry(*NewRefDie)); + return AttrSize; +} + +/// \brief Clone an attribute of block form (locations, constants) and add +/// it to \p Die. +/// \returns the size of the new attribute. +unsigned DwarfLinker::cloneBlockAttribute(DIE &Die, AttributeSpec AttrSpec, + const DWARFFormValue &Val, + unsigned AttrSize) { + DIE *Attr; + DIEValue *Value; + DIELoc *Loc = nullptr; + DIEBlock *Block = nullptr; + // Just copy the block data over. + if (AttrSpec.Form == dwarf::DW_FORM_exprloc) { + Loc = new (DIEAlloc) DIELoc(); + DIELocs.push_back(Loc); + } else { + Block = new (DIEAlloc) DIEBlock(); + DIEBlocks.push_back(Block); + } + Attr = Loc ? static_cast<DIE *>(Loc) : static_cast<DIE *>(Block); + Value = Loc ? static_cast<DIEValue *>(Loc) : static_cast<DIEValue *>(Block); + ArrayRef<uint8_t> Bytes = *Val.getAsBlock(); + for (auto Byte : Bytes) + Attr->addValue(static_cast<dwarf::Attribute>(0), dwarf::DW_FORM_data1, + new (DIEAlloc) DIEInteger(Byte)); + // FIXME: If DIEBlock and DIELoc just reuses the Size field of + // the DIE class, this if could be replaced by + // Attr->setSize(Bytes.size()). + if (Streamer) { + if (Loc) + Loc->ComputeSize(&Streamer->getAsmPrinter()); + else + Block->ComputeSize(&Streamer->getAsmPrinter()); + } + Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::Form(AttrSpec.Form), + Value); + return AttrSize; +} + +/// \brief Clone an address attribute and add it to \p Die. +/// \returns the size of the new attribute. +unsigned DwarfLinker::cloneAddressAttribute(DIE &Die, AttributeSpec AttrSpec, + const DWARFFormValue &Val, + const CompileUnit &Unit, + AttributesInfo &Info) { + uint64_t Addr = *Val.getAsAddress(&Unit.getOrigUnit()); + if (AttrSpec.Attr == dwarf::DW_AT_low_pc) { + if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine || + Die.getTag() == dwarf::DW_TAG_lexical_block) + Addr += Info.PCOffset; + else if (Die.getTag() == dwarf::DW_TAG_compile_unit) { + Addr = Unit.getLowPc(); + if (Addr == UINT64_MAX) + return 0; + } + Info.HasLowPc = true; + } else if (AttrSpec.Attr == dwarf::DW_AT_high_pc) { + if (Die.getTag() == dwarf::DW_TAG_compile_unit) { + if (uint64_t HighPc = Unit.getHighPc()) + Addr = HighPc; + else + return 0; + } else + // If we have a high_pc recorded for the input DIE, use + // it. Otherwise (when no relocations where applied) just use the + // one we just decoded. + Addr = (Info.OrigHighPc ? Info.OrigHighPc : Addr) + Info.PCOffset; + } + + Die.addValue(static_cast<dwarf::Attribute>(AttrSpec.Attr), + static_cast<dwarf::Form>(AttrSpec.Form), + new (DIEAlloc) DIEInteger(Addr)); + return Unit.getOrigUnit().getAddressByteSize(); +} + +/// \brief Clone a scalar attribute and add it to \p Die. +/// \returns the size of the new attribute. +unsigned DwarfLinker::cloneScalarAttribute( + DIE &Die, const DWARFDebugInfoEntryMinimal &InputDIE, CompileUnit &Unit, + AttributeSpec AttrSpec, const DWARFFormValue &Val, unsigned AttrSize, + AttributesInfo &Info) { + uint64_t Value; + if (AttrSpec.Attr == dwarf::DW_AT_high_pc && + Die.getTag() == dwarf::DW_TAG_compile_unit) { + if (Unit.getLowPc() == -1ULL) + return 0; + // Dwarf >= 4 high_pc is an size, not an address. + Value = Unit.getHighPc() - Unit.getLowPc(); + } else if (AttrSpec.Form == dwarf::DW_FORM_sec_offset) + Value = *Val.getAsSectionOffset(); + else if (AttrSpec.Form == dwarf::DW_FORM_sdata) + Value = *Val.getAsSignedConstant(); + else if (auto OptionalValue = Val.getAsUnsignedConstant()) + Value = *OptionalValue; + else { + reportWarning("Unsupported scalar attribute form. Dropping attribute.", + &Unit.getOrigUnit(), &InputDIE); + return 0; + } + DIEInteger *Attr = new (DIEAlloc) DIEInteger(Value); + if (AttrSpec.Attr == dwarf::DW_AT_ranges) + Unit.noteRangeAttribute(Die, Attr); + // A more generic way to check for location attributes would be + // nice, but it's very unlikely that any other attribute needs a + // location list. + else if (AttrSpec.Attr == dwarf::DW_AT_location || + AttrSpec.Attr == dwarf::DW_AT_frame_base) + Unit.noteLocationAttribute(Attr, Info.PCOffset); + else if (AttrSpec.Attr == dwarf::DW_AT_declaration && Value) + Info.IsDeclaration = true; + + Die.addValue(dwarf::Attribute(AttrSpec.Attr), dwarf::Form(AttrSpec.Form), + Attr); + return AttrSize; +} + +/// \brief Clone \p InputDIE's attribute described by \p AttrSpec with +/// value \p Val, and add it to \p Die. +/// \returns the size of the cloned attribute. +unsigned DwarfLinker::cloneAttribute(DIE &Die, + const DWARFDebugInfoEntryMinimal &InputDIE, + CompileUnit &Unit, + const DWARFFormValue &Val, + const AttributeSpec AttrSpec, + unsigned AttrSize, AttributesInfo &Info) { + const DWARFUnit &U = Unit.getOrigUnit(); + + switch (AttrSpec.Form) { + case dwarf::DW_FORM_strp: + case dwarf::DW_FORM_string: + return cloneStringAttribute(Die, AttrSpec, Val, U); + case dwarf::DW_FORM_ref_addr: + case dwarf::DW_FORM_ref1: + case dwarf::DW_FORM_ref2: + case dwarf::DW_FORM_ref4: + case dwarf::DW_FORM_ref8: + return cloneDieReferenceAttribute(Die, InputDIE, AttrSpec, AttrSize, Val, + Unit); + case dwarf::DW_FORM_block: + case dwarf::DW_FORM_block1: + case dwarf::DW_FORM_block2: + case dwarf::DW_FORM_block4: + case dwarf::DW_FORM_exprloc: + return cloneBlockAttribute(Die, AttrSpec, Val, AttrSize); + case dwarf::DW_FORM_addr: + return cloneAddressAttribute(Die, AttrSpec, Val, Unit, Info); + case dwarf::DW_FORM_data1: + case dwarf::DW_FORM_data2: + case dwarf::DW_FORM_data4: + case dwarf::DW_FORM_data8: + case dwarf::DW_FORM_udata: + case dwarf::DW_FORM_sdata: + case dwarf::DW_FORM_sec_offset: + case dwarf::DW_FORM_flag: + case dwarf::DW_FORM_flag_present: + return cloneScalarAttribute(Die, InputDIE, Unit, AttrSpec, Val, AttrSize, + Info); + default: + reportWarning("Unsupported attribute form in cloneAttribute. Dropping.", &U, + &InputDIE); + } + + return 0; +} + +/// \brief Apply the valid relocations found by findValidRelocs() to +/// the buffer \p Data, taking into account that Data is at \p BaseOffset +/// in the debug_info section. +/// +/// Like for findValidRelocs(), this function must be called with +/// monotonic \p BaseOffset values. +/// +/// \returns wether any reloc has been applied. +bool DwarfLinker::applyValidRelocs(MutableArrayRef<char> Data, + uint32_t BaseOffset, bool isLittleEndian) { + assert((NextValidReloc == 0 || + BaseOffset > ValidRelocs[NextValidReloc - 1].Offset) && + "BaseOffset should only be increasing."); + if (NextValidReloc >= ValidRelocs.size()) + return false; + + // Skip relocs that haven't been applied. + while (NextValidReloc < ValidRelocs.size() && + ValidRelocs[NextValidReloc].Offset < BaseOffset) + ++NextValidReloc; + + bool Applied = false; + uint64_t EndOffset = BaseOffset + Data.size(); + while (NextValidReloc < ValidRelocs.size() && + ValidRelocs[NextValidReloc].Offset >= BaseOffset && + ValidRelocs[NextValidReloc].Offset < EndOffset) { + const auto &ValidReloc = ValidRelocs[NextValidReloc++]; + assert(ValidReloc.Offset - BaseOffset < Data.size()); + assert(ValidReloc.Offset - BaseOffset + ValidReloc.Size <= Data.size()); + char Buf[8]; + uint64_t Value = ValidReloc.Mapping->getValue().BinaryAddress; + Value += ValidReloc.Addend; + for (unsigned i = 0; i != ValidReloc.Size; ++i) { + unsigned Index = isLittleEndian ? i : (ValidReloc.Size - i - 1); + Buf[i] = uint8_t(Value >> (Index * 8)); + } + assert(ValidReloc.Size <= sizeof(Buf)); + memcpy(&Data[ValidReloc.Offset - BaseOffset], Buf, ValidReloc.Size); + Applied = true; + } + + return Applied; +} + +static bool isTypeTag(uint16_t Tag) { + switch (Tag) { + case dwarf::DW_TAG_array_type: + case dwarf::DW_TAG_class_type: + case dwarf::DW_TAG_enumeration_type: + case dwarf::DW_TAG_pointer_type: + case dwarf::DW_TAG_reference_type: + case dwarf::DW_TAG_string_type: + case dwarf::DW_TAG_structure_type: + case dwarf::DW_TAG_subroutine_type: + case dwarf::DW_TAG_typedef: + case dwarf::DW_TAG_union_type: + case dwarf::DW_TAG_ptr_to_member_type: + case dwarf::DW_TAG_set_type: + case dwarf::DW_TAG_subrange_type: + case dwarf::DW_TAG_base_type: + case dwarf::DW_TAG_const_type: + case dwarf::DW_TAG_constant: + case dwarf::DW_TAG_file_type: + case dwarf::DW_TAG_namelist: + case dwarf::DW_TAG_packed_type: + case dwarf::DW_TAG_volatile_type: + case dwarf::DW_TAG_restrict_type: + case dwarf::DW_TAG_interface_type: + case dwarf::DW_TAG_unspecified_type: + case dwarf::DW_TAG_shared_type: + return true; + default: + break; + } + return false; +} + +/// \brief Recursively clone \p InputDIE's subtrees that have been +/// selected to appear in the linked output. +/// +/// \param OutOffset is the Offset where the newly created DIE will +/// lie in the linked compile unit. +/// +/// \returns the cloned DIE object or null if nothing was selected. +DIE *DwarfLinker::cloneDIE(const DWARFDebugInfoEntryMinimal &InputDIE, + CompileUnit &Unit, int64_t PCOffset, + uint32_t OutOffset) { + DWARFUnit &U = Unit.getOrigUnit(); + unsigned Idx = U.getDIEIndex(&InputDIE); + CompileUnit::DIEInfo &Info = Unit.getInfo(Idx); + + // Should the DIE appear in the output? + if (!Unit.getInfo(Idx).Keep) + return nullptr; + + uint32_t Offset = InputDIE.getOffset(); + // The DIE might have been already created by a forward reference + // (see cloneDieReferenceAttribute()). + DIE *Die = Info.Clone; + if (!Die) + Die = Info.Clone = new DIE(dwarf::Tag(InputDIE.getTag())); + assert(Die->getTag() == InputDIE.getTag()); + Die->setOffset(OutOffset); + + // Extract and clone every attribute. + DataExtractor Data = U.getDebugInfoExtractor(); + uint32_t NextOffset = U.getDIEAtIndex(Idx + 1)->getOffset(); + AttributesInfo AttrInfo; + + // We could copy the data only if we need to aply a relocation to + // it. After testing, it seems there is no performance downside to + // doing the copy unconditionally, and it makes the code simpler. + SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset)); + Data = DataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize()); + // Modify the copy with relocated addresses. + if (applyValidRelocs(DIECopy, Offset, Data.isLittleEndian())) { + // If we applied relocations, we store the value of high_pc that was + // potentially stored in the input DIE. If high_pc is an address + // (Dwarf version == 2), then it might have been relocated to a + // totally unrelated value (because the end address in the object + // file might be start address of another function which got moved + // independantly by the linker). The computation of the actual + // high_pc value is done in cloneAddressAttribute(). + AttrInfo.OrigHighPc = + InputDIE.getAttributeValueAsAddress(&U, dwarf::DW_AT_high_pc, 0); + } + + // Reset the Offset to 0 as we will be working on the local copy of + // the data. + Offset = 0; + + const auto *Abbrev = InputDIE.getAbbreviationDeclarationPtr(); + Offset += getULEB128Size(Abbrev->getCode()); + + // We are entering a subprogram. Get and propagate the PCOffset. + if (Die->getTag() == dwarf::DW_TAG_subprogram) + PCOffset = Info.AddrAdjust; + AttrInfo.PCOffset = PCOffset; + + for (const auto &AttrSpec : Abbrev->attributes()) { + DWARFFormValue Val(AttrSpec.Form); + uint32_t AttrSize = Offset; + Val.extractValue(Data, &Offset, &U); + AttrSize = Offset - AttrSize; + + OutOffset += + cloneAttribute(*Die, InputDIE, Unit, Val, AttrSpec, AttrSize, AttrInfo); + } + + // Look for accelerator entries. + uint16_t Tag = InputDIE.getTag(); + // FIXME: This is slightly wrong. An inline_subroutine without a + // low_pc, but with AT_ranges might be interesting to get into the + // accelerator tables too. For now stick with dsymutil's behavior. + if ((Info.InDebugMap || AttrInfo.HasLowPc) && + Tag != dwarf::DW_TAG_compile_unit && + getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) { + if (AttrInfo.MangledName && AttrInfo.MangledName != AttrInfo.Name) + Unit.addNameAccelerator(Die, AttrInfo.MangledName, + AttrInfo.MangledNameOffset, + Tag == dwarf::DW_TAG_inlined_subroutine); + if (AttrInfo.Name) + Unit.addNameAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset, + Tag == dwarf::DW_TAG_inlined_subroutine); + } else if (isTypeTag(Tag) && !AttrInfo.IsDeclaration && + getDIENames(InputDIE, Unit.getOrigUnit(), AttrInfo)) { + Unit.addTypeAccelerator(Die, AttrInfo.Name, AttrInfo.NameOffset); + } + + DIEAbbrev &NewAbbrev = Die->getAbbrev(); + // If a scope DIE is kept, we must have kept at least one child. If + // it's not the case, we'll just be emitting one wasteful end of + // children marker, but things won't break. + if (InputDIE.hasChildren()) + NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes); + // Assign a permanent abbrev number + AssignAbbrev(Die->getAbbrev()); + + // Add the size of the abbreviation number to the output offset. + OutOffset += getULEB128Size(Die->getAbbrevNumber()); + + if (!Abbrev->hasChildren()) { + // Update our size. + Die->setSize(OutOffset - Die->getOffset()); + return Die; + } + + // Recursively clone children. + for (auto *Child = InputDIE.getFirstChild(); Child && !Child->isNULL(); + Child = Child->getSibling()) { + if (DIE *Clone = cloneDIE(*Child, Unit, PCOffset, OutOffset)) { + Die->addChild(std::unique_ptr<DIE>(Clone)); + OutOffset = Clone->getOffset() + Clone->getSize(); + } + } + + // Account for the end of children marker. + OutOffset += sizeof(int8_t); + // Update our size. + Die->setSize(OutOffset - Die->getOffset()); + return Die; +} + +/// \brief Patch the input object file relevant debug_ranges entries +/// and emit them in the output file. Update the relevant attributes +/// to point at the new entries. +void DwarfLinker::patchRangesForUnit(const CompileUnit &Unit, + DWARFContext &OrigDwarf) const { + DWARFDebugRangeList RangeList; + const auto &FunctionRanges = Unit.getFunctionRanges(); + unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize(); + DataExtractor RangeExtractor(OrigDwarf.getRangeSection(), + OrigDwarf.isLittleEndian(), AddressSize); + auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange; + DWARFUnit &OrigUnit = Unit.getOrigUnit(); + const auto *OrigUnitDie = OrigUnit.getCompileUnitDIE(false); + uint64_t OrigLowPc = OrigUnitDie->getAttributeValueAsAddress( + &OrigUnit, dwarf::DW_AT_low_pc, -1ULL); + // Ranges addresses are based on the unit's low_pc. Compute the + // offset we need to apply to adapt to the the new unit's low_pc. + int64_t UnitPcOffset = 0; + if (OrigLowPc != -1ULL) + UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc(); + + for (const auto &RangeAttribute : Unit.getRangesAttributes()) { + uint32_t Offset = RangeAttribute->getValue(); + RangeAttribute->setValue(Streamer->getRangesSectionSize()); + RangeList.extract(RangeExtractor, &Offset); + const auto &Entries = RangeList.getEntries(); + const DWARFDebugRangeList::RangeListEntry &First = Entries.front(); + + if (CurrRange == InvalidRange || First.StartAddress < CurrRange.start() || + First.StartAddress >= CurrRange.stop()) { + CurrRange = FunctionRanges.find(First.StartAddress + OrigLowPc); + if (CurrRange == InvalidRange || + CurrRange.start() > First.StartAddress + OrigLowPc) { + reportWarning("no mapping for range."); + continue; + } + } + + Streamer->emitRangesEntries(UnitPcOffset, OrigLowPc, CurrRange, Entries, + AddressSize); + } +} + +/// \brief Generate the debug_aranges entries for \p Unit and if the +/// unit has a DW_AT_ranges attribute, also emit the debug_ranges +/// contribution for this attribute. +/// FIXME: this could actually be done right in patchRangesForUnit, +/// but for the sake of initial bit-for-bit compatibility with legacy +/// dsymutil, we have to do it in a delayed pass. +void DwarfLinker::generateUnitRanges(CompileUnit &Unit) const { + DIEInteger *Attr = Unit.getUnitRangesAttribute(); + if (Attr) + Attr->setValue(Streamer->getRangesSectionSize()); + Streamer->emitUnitRangesEntries(Unit, Attr != nullptr); +} + +/// \brief Insert the new line info sequence \p Seq into the current +/// set of already linked line info \p Rows. +static void insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq, + std::vector<DWARFDebugLine::Row> &Rows) { + if (Seq.empty()) + return; + + if (!Rows.empty() && Rows.back().Address < Seq.front().Address) { + Rows.insert(Rows.end(), Seq.begin(), Seq.end()); + Seq.clear(); + return; + } + + auto InsertPoint = std::lower_bound( + Rows.begin(), Rows.end(), Seq.front(), + [](const DWARFDebugLine::Row &LHS, const DWARFDebugLine::Row &RHS) { + return LHS.Address < RHS.Address; + }); + + // FIXME: this only removes the unneeded end_sequence if the + // sequences have been inserted in order. using a global sort like + // described in patchLineTableForUnit() and delaying the end_sequene + // elimination to emitLineTableForUnit() we can get rid of all of them. + if (InsertPoint != Rows.end() && + InsertPoint->Address == Seq.front().Address && InsertPoint->EndSequence) { + *InsertPoint = Seq.front(); + Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end()); + } else { + Rows.insert(InsertPoint, Seq.begin(), Seq.end()); + } + + Seq.clear(); +} + +/// \brief Extract the line table for \p Unit from \p OrigDwarf, and +/// recreate a relocated version of these for the address ranges that +/// are present in the binary. +void DwarfLinker::patchLineTableForUnit(CompileUnit &Unit, + DWARFContext &OrigDwarf) { + const DWARFDebugInfoEntryMinimal *CUDie = + Unit.getOrigUnit().getCompileUnitDIE(); + uint64_t StmtList = CUDie->getAttributeValueAsSectionOffset( + &Unit.getOrigUnit(), dwarf::DW_AT_stmt_list, -1ULL); + if (StmtList == -1ULL) + return; + + // Update the cloned DW_AT_stmt_list with the correct debug_line offset. + if (auto *OutputDIE = Unit.getOutputUnitDIE()) { + const auto &Abbrev = OutputDIE->getAbbrev().getData(); + auto Stmt = std::find_if( + Abbrev.begin(), Abbrev.end(), [](const DIEAbbrevData &AbbrevData) { + return AbbrevData.getAttribute() == dwarf::DW_AT_stmt_list; + }); + assert(Stmt < Abbrev.end() && "Didn't find DW_AT_stmt_list in cloned DIE!"); + DIEInteger *StmtAttr = + cast<DIEInteger>(OutputDIE->getValues()[Stmt - Abbrev.begin()]); + StmtAttr->setValue(Streamer->getLineSectionSize()); + } + + // Parse the original line info for the unit. + DWARFDebugLine::LineTable LineTable; + uint32_t StmtOffset = StmtList; + StringRef LineData = OrigDwarf.getLineSection().Data; + DataExtractor LineExtractor(LineData, OrigDwarf.isLittleEndian(), + Unit.getOrigUnit().getAddressByteSize()); + LineTable.parse(LineExtractor, &OrigDwarf.getLineSection().Relocs, + &StmtOffset); + + // This vector is the output line table. + std::vector<DWARFDebugLine::Row> NewRows; + NewRows.reserve(LineTable.Rows.size()); + + // Current sequence of rows being extracted, before being inserted + // in NewRows. + std::vector<DWARFDebugLine::Row> Seq; + const auto &FunctionRanges = Unit.getFunctionRanges(); + auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange; + + // FIXME: This logic is meant to generate exactly the same output as + // Darwin's classic dsynutil. There is a nicer way to implement this + // by simply putting all the relocated line info in NewRows and simply + // sorting NewRows before passing it to emitLineTableForUnit. This + // should be correct as sequences for a function should stay + // together in the sorted output. There are a few corner cases that + // look suspicious though, and that required to implement the logic + // this way. Revisit that once initial validation is finished. + + // Iterate over the object file line info and extract the sequences + // that correspond to linked functions. + for (auto &Row : LineTable.Rows) { + // Check wether we stepped out of the range. The range is + // half-open, but consider accept the end address of the range if + // it is marked as end_sequence in the input (because in that + // case, the relocation offset is accurate and that entry won't + // serve as the start of another function). + if (CurrRange == InvalidRange || Row.Address < CurrRange.start() || + Row.Address > CurrRange.stop() || + (Row.Address == CurrRange.stop() && !Row.EndSequence)) { + // We just stepped out of a known range. Insert a end_sequence + // corresponding to the end of the range. + uint64_t StopAddress = CurrRange != InvalidRange + ? CurrRange.stop() + CurrRange.value() + : -1ULL; + CurrRange = FunctionRanges.find(Row.Address); + bool CurrRangeValid = + CurrRange != InvalidRange && CurrRange.start() <= Row.Address; + if (!CurrRangeValid) { + CurrRange = InvalidRange; + if (StopAddress != -1ULL) { + // Try harder by looking in the DebugMapObject function + // ranges map. There are corner cases where this finds a + // valid entry. It's unclear if this is right or wrong, but + // for now do as dsymutil. + // FIXME: Understand exactly what cases this addresses and + // potentially remove it along with the Ranges map. + auto Range = Ranges.lower_bound(Row.Address); + if (Range != Ranges.begin() && Range != Ranges.end()) + --Range; + + if (Range != Ranges.end() && Range->first <= Row.Address && + Range->second.first >= Row.Address) { + StopAddress = Row.Address + Range->second.second; + } + } + } + if (StopAddress != -1ULL && !Seq.empty()) { + // Insert end sequence row with the computed end address, but + // the same line as the previous one. + Seq.emplace_back(Seq.back()); + Seq.back().Address = StopAddress; + Seq.back().EndSequence = 1; + Seq.back().PrologueEnd = 0; + Seq.back().BasicBlock = 0; + Seq.back().EpilogueBegin = 0; + insertLineSequence(Seq, NewRows); + } + + if (!CurrRangeValid) + continue; + } + + // Ignore empty sequences. + if (Row.EndSequence && Seq.empty()) + continue; + + // Relocate row address and add it to the current sequence. + Row.Address += CurrRange.value(); + Seq.emplace_back(Row); + + if (Row.EndSequence) + insertLineSequence(Seq, NewRows); + } + + // Finished extracting, now emit the line tables. + uint32_t PrologueEnd = StmtList + 10 + LineTable.Prologue.PrologueLength; + // FIXME: LLVM hardcodes it's prologue values. We just copy the + // prologue over and that works because we act as both producer and + // consumer. It would be nicer to have a real configurable line + // table emitter. + if (LineTable.Prologue.Version != 2 || + LineTable.Prologue.DefaultIsStmt != DWARF2_LINE_DEFAULT_IS_STMT || + LineTable.Prologue.LineBase != -5 || LineTable.Prologue.LineRange != 14 || + LineTable.Prologue.OpcodeBase != 13) + reportWarning("line table paramters mismatch. Cannot emit."); + else + Streamer->emitLineTableForUnit(LineData.slice(StmtList + 4, PrologueEnd), + LineTable.Prologue.MinInstLength, NewRows, + Unit.getOrigUnit().getAddressByteSize()); +} + +void DwarfLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) { + Streamer->emitPubNamesForUnit(Unit); + Streamer->emitPubTypesForUnit(Unit); +} + bool DwarfLinker::link(const DebugMap &Map) { if (Map.begin() == Map.end()) { @@ -608,10 +2428,17 @@ bool DwarfLinker::link(const DebugMap &Map) { return false; } + if (!createStreamer(Map.getTriple(), OutputFilename)) + return false; + + // Size of the DIEs (and headers) generated for the linked output. + uint64_t OutputDebugInfoSize = 0; + // A unique ID that identifies each compile unit. + unsigned UnitID = 0; for (const auto &Obj : Map.objects()) { CurrentDebugObject = Obj.get(); - if (Verbose) + if (Options.Verbose) outs() << "DEBUG MAP OBJECT: " << Obj->getObjectFilename() << "\n"; auto ErrOrObj = BinHolder.GetObjectFile(Obj->getObjectFilename()); if (std::error_code EC = ErrOrObj.getError()) { @@ -621,24 +2448,24 @@ bool DwarfLinker::link(const DebugMap &Map) { // Look for relocations that correspond to debug map entries. if (!findValidRelocsInDebugInfo(*ErrOrObj, *Obj)) { - if (Verbose) + if (Options.Verbose) outs() << "No valid relocations found. Skipping.\n"; continue; } // Setup access to the debug info. DWARFContextInMemory DwarfContext(*ErrOrObj); - startDebugObject(DwarfContext); + startDebugObject(DwarfContext, *Obj); // In a first phase, just read in the debug info and store the DIE // parent links that we will use during the next phase. for (const auto &CU : DwarfContext.compile_units()) { auto *CUDie = CU->getCompileUnitDIE(false); - if (Verbose) { + if (Options.Verbose) { outs() << "Input compilation unit:"; CUDie->dump(outs(), CU.get(), 0); } - Units.emplace_back(*CU); + Units.emplace_back(*CU, UnitID++); gatherDIEParents(CUDie, 0, Units.back()); } @@ -651,16 +2478,63 @@ bool DwarfLinker::link(const DebugMap &Map) { lookForDIEsToKeep(*CurrentUnit.getOrigUnit().getCompileUnitDIE(), *Obj, CurrentUnit, 0); + // The calls to applyValidRelocs inside cloneDIE will walk the + // reloc array again (in the same way findValidRelocsInDebugInfo() + // did). We need to reset the NextValidReloc index to the beginning. + NextValidReloc = 0; + + // Construct the output DIE tree by cloning the DIEs we chose to + // keep above. If there are no valid relocs, then there's nothing + // to clone/emit. + if (!ValidRelocs.empty()) + for (auto &CurrentUnit : Units) { + const auto *InputDIE = CurrentUnit.getOrigUnit().getCompileUnitDIE(); + CurrentUnit.setStartOffset(OutputDebugInfoSize); + DIE *OutputDIE = cloneDIE(*InputDIE, CurrentUnit, 0 /* PCOffset */, + 11 /* Unit Header size */); + CurrentUnit.setOutputUnitDIE(OutputDIE); + OutputDebugInfoSize = CurrentUnit.computeNextUnitOffset(); + if (Options.NoOutput) + continue; + // FIXME: for compatibility with the classic dsymutil, we emit + // an empty line table for the unit, even if the unit doesn't + // actually exist in the DIE tree. + patchLineTableForUnit(CurrentUnit, DwarfContext); + if (!OutputDIE) + continue; + patchRangesForUnit(CurrentUnit, DwarfContext); + Streamer->emitLocationsForUnit(CurrentUnit, DwarfContext); + emitAcceleratorEntriesForUnit(CurrentUnit); + } + + // Emit all the compile unit's debug information. + if (!ValidRelocs.empty() && !Options.NoOutput) + for (auto &CurrentUnit : Units) { + generateUnitRanges(CurrentUnit); + CurrentUnit.fixupForwardReferences(); + Streamer->emitCompileUnitHeader(CurrentUnit); + if (!CurrentUnit.getOutputUnitDIE()) + continue; + Streamer->emitDIE(*CurrentUnit.getOutputUnitDIE()); + } + // Clean-up before starting working on the next object. endDebugObject(); } - return true; + // Emit everything that's global. + if (!Options.NoOutput) { + Streamer->emitAbbrevs(Abbreviations); + Streamer->emitStrings(StringPool); + } + + return Options.NoOutput ? true : Streamer->finish(); } } -bool linkDwarf(StringRef OutputFilename, const DebugMap &DM, bool Verbose) { - DwarfLinker Linker(OutputFilename, Verbose); +bool linkDwarf(StringRef OutputFilename, const DebugMap &DM, + const LinkOptions &Options) { + DwarfLinker Linker(OutputFilename, Options); return Linker.link(DM); } } |