X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FMC%2FELFObjectWriter.cpp;h=cc16ac8fa1e232601a5bf3eecbb8e0eb8b35fe70;hb=c16fc548515f2fd01bc2cbe4befd822a636cc154;hp=e9b8fe296581653634dee752e40df897672ddf29;hpb=5d853bf42d854ba45615dfda928088ec5edf06c7;p=oota-llvm.git diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp index e9b8fe29658..cc16ac8fa1e 100644 --- a/lib/MC/ELFObjectWriter.cpp +++ b/lib/MC/ELFObjectWriter.cpp @@ -17,6 +17,7 @@ #include "llvm/ADT/SmallString.h" #include "llvm/ADT/StringMap.h" #include "llvm/MC/MCAsmBackend.h" +#include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCAsmLayout.h" #include "llvm/MC/MCAssembler.h" #include "llvm/MC/MCContext.h" @@ -27,9 +28,11 @@ #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCValue.h" +#include "llvm/MC/StringTableBuilder.h" +#include "llvm/Support/Compression.h" #include "llvm/Support/Debug.h" -#include "llvm/Support/Endian.h" #include "llvm/Support/ELF.h" +#include "llvm/Support/Endian.h" #include "llvm/Support/ErrorHandling.h" #include using namespace llvm; @@ -78,23 +81,13 @@ public: struct ELFRelocationEntry { uint64_t Offset; // Where is the relocation. - bool UseSymbol; // Relocate with a symbol, not the section. - union { - const MCSymbol *Symbol; // The symbol to relocate with. - const MCSectionData *Section; // The section to relocate with. - }; + const MCSymbol *Symbol; // The symbol to relocate with. unsigned Type; // The type of the relocation. uint64_t Addend; // The addend to use. ELFRelocationEntry(uint64_t Offset, const MCSymbol *Symbol, unsigned Type, uint64_t Addend) - : Offset(Offset), UseSymbol(true), Symbol(Symbol), Type(Type), - Addend(Addend) {} - - ELFRelocationEntry(uint64_t Offset, const MCSectionData *Section, - unsigned Type, uint64_t Addend) - : Offset(Offset), UseSymbol(false), Section(Section), Type(Type), - Addend(Addend) {} + : Offset(Offset), Symbol(Symbol), Type(Type), Addend(Addend) {} }; class ELFObjectWriter : public MCObjectWriter { @@ -105,10 +98,9 @@ class ELFObjectWriter : public MCObjectWriter { static bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind); static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant); static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout); - static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data, + static bool isInSymtab(const MCAsmLayout &Layout, const MCSymbolData &Data, bool Used, bool Renamed); - static bool isLocal(const MCSymbolData &Data, bool isSignature, - bool isUsedInReloc); + static bool isLocal(const MCSymbolData &Data, bool isUsedInReloc); static bool IsELFMetaDataSection(const MCSectionData &SD); static uint64_t DataSectionSize(const MCSectionData &SD); static uint64_t GetSectionFileSize(const MCAsmLayout &Layout, @@ -120,22 +112,24 @@ class ELFObjectWriter : public MCObjectWriter { const MCAsmLayout &Layout, const MCSectionELF &Section); - /*static bool isFixupKindX86RIPRel(unsigned Kind) { - return Kind == X86::reloc_riprel_4byte || - Kind == X86::reloc_riprel_4byte_movq_load; - }*/ - - /// ELFSymbolData - Helper struct for containing some precomputed - /// information on symbols. + /// Helper struct for containing some precomputed information on symbols. struct ELFSymbolData { MCSymbolData *SymbolData; uint64_t StringIndex; uint32_t SectionIndex; + StringRef Name; // Support lexicographic sorting. bool operator<(const ELFSymbolData &RHS) const { - return SymbolData->getSymbol().getName() < - RHS.SymbolData->getSymbol().getName(); + unsigned LHSType = MCELF::GetType(*SymbolData); + unsigned RHSType = MCELF::GetType(*RHS.SymbolData); + if (LHSType == ELF::STT_SECTION && RHSType != ELF::STT_SECTION) + return false; + if (LHSType != ELF::STT_SECTION && RHSType == ELF::STT_SECTION) + return true; + if (LHSType == ELF::STT_SECTION && RHSType == ELF::STT_SECTION) + return SectionIndex < RHS.SectionIndex; + return Name < RHS.Name; } }; @@ -148,13 +142,13 @@ class ELFObjectWriter : public MCObjectWriter { llvm::DenseMap> Relocations; - DenseMap SectionStringTableIndex; + StringTableBuilder ShStrTabBuilder; /// @} /// @name Symbol Table Data /// @{ - SmallString<256> StringTable; + StringTableBuilder StrTabBuilder; std::vector FileSymbolData; std::vector LocalSymbolData; std::vector ExternalSymbolData; @@ -185,12 +179,26 @@ class ELFObjectWriter : public MCObjectWriter { } public: - ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS, + ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &OS, bool IsLittleEndian) - : MCObjectWriter(_OS, IsLittleEndian), FWriter(IsLittleEndian), + : MCObjectWriter(OS, IsLittleEndian), FWriter(IsLittleEndian), TargetObjectWriter(MOTW), NeedsGOT(false) {} - virtual ~ELFObjectWriter(); + void reset() override { + UsedInReloc.clear(); + WeakrefUsedInReloc.clear(); + Renames.clear(); + Relocations.clear(); + ShStrTabBuilder.clear(); + StrTabBuilder.clear(); + FileSymbolData.clear(); + LocalSymbolData.clear(); + ExternalSymbolData.clear(); + UndefinedSymbolData.clear(); + MCObjectWriter::reset(); + } + + ~ELFObjectWriter() override; void WriteWord(uint64_t W) { if (is64Bit()) @@ -204,7 +212,7 @@ class ELFObjectWriter : public MCObjectWriter { } void WriteHeader(const MCAssembler &Asm, - uint64_t SectionDataSize, + uint64_t SectionHeaderOffset, unsigned NumberOfSections); void WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD, @@ -214,11 +222,12 @@ class ELFObjectWriter : public MCObjectWriter { const MCAsmLayout &Layout, SectionIndexMapTy &SectionIndexMap); - bool shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA, + bool shouldRelocateWithSymbol(const MCAssembler &Asm, + const MCSymbolRefExpr *RefA, const MCSymbolData *SD, uint64_t C, unsigned Type) const; - void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout, + void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) override; @@ -230,8 +239,6 @@ class ELFObjectWriter : public MCObjectWriter { typedef DenseMap GroupMapTy; // Map from a signature symbol to the group section typedef DenseMap RevGroupMapTy; - // Map from a section to the section with the relocations - typedef DenseMap RelMapTy; // Map from a section to its offset typedef DenseMap SectionOffsetMapTy; @@ -240,38 +247,32 @@ class ELFObjectWriter : public MCObjectWriter { /// \param Asm - The assembler. /// \param SectionIndexMap - Maps a section to its index. /// \param RevGroupMap - Maps a signature symbol to the group section. - /// \param NumRegularSections - Number of non-relocation sections. void computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap, - RevGroupMapTy RevGroupMap, - unsigned NumRegularSections); + const RevGroupMapTy &RevGroupMap); + + void computeIndexMap(MCAssembler &Asm, SectionIndexMapTy &SectionIndexMap); - void ComputeIndexMap(MCAssembler &Asm, - SectionIndexMapTy &SectionIndexMap, - const RelMapTy &RelMap); + MCSectionData *createRelocationSection(MCAssembler &Asm, + const MCSectionData &SD); - void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout, - RelMapTy &RelMap); + void CompressDebugSections(MCAssembler &Asm, MCAsmLayout &Layout); - void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout, - const RelMapTy &RelMap); + void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout); void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout, - SectionIndexMapTy &SectionIndexMap, - const RelMapTy &RelMap); + SectionIndexMapTy &SectionIndexMap); // Create the sections that show up in the symbol table. Currently // those are the .note.GNU-stack section and the group sections. - void CreateIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout, - GroupMapTy &GroupMap, - RevGroupMapTy &RevGroupMap, - SectionIndexMapTy &SectionIndexMap, - const RelMapTy &RelMap); + void createIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout, + GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap, + SectionIndexMapTy &SectionIndexMap); void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout) override; - void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap, + void writeSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap, const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap, const SectionOffsetMapTy &SectionOffsetMap); @@ -291,12 +292,15 @@ class ELFObjectWriter : public MCObjectWriter { bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, const MCSymbolData &DataA, + const MCSymbolData *DataB, const MCFragment &FB, bool InSet, bool IsPCRel) const override; + bool isWeak(const MCSymbolData &SD) const override; + void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; - void WriteSection(MCAssembler &Asm, + void writeSection(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size, uint64_t Alignment, @@ -322,8 +326,7 @@ void SymbolTableWriter::createSymtabShndx() { MCContext &Ctx = Asm.getContext(); const MCSectionELF *SymtabShndxSection = - Ctx.getELFSection(".symtab_shndxr", ELF::SHT_SYMTAB_SHNDX, 0, - SectionKind::getReadOnly(), 4, ""); + Ctx.getELFSection(".symtab_shndxr", ELF::SHT_SYMTAB_SHNDX, 0, 4, ""); MCSectionData *SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection); SymtabShndxSD->setAlignment(4); @@ -365,8 +368,6 @@ void SymbolTableWriter::writeSymbol(uint32_t name, uint8_t info, uint64_t value, uint16_t Index = LargeIndex ? uint16_t(ELF::SHN_XINDEX) : shndx; - raw_svector_ostream OS(SymtabF->getContents()); - if (Is64Bit) { write(*SymtabF, name); // st_name write(*SymtabF, info); // st_info @@ -419,7 +420,7 @@ ELFObjectWriter::~ELFObjectWriter() // Emit the ELF header. void ELFObjectWriter::WriteHeader(const MCAssembler &Asm, - uint64_t SectionDataSize, + uint64_t SectionHeaderOffset, unsigned NumberOfSections) { // ELF Header // ---------- @@ -453,8 +454,7 @@ void ELFObjectWriter::WriteHeader(const MCAssembler &Asm, Write32(ELF::EV_CURRENT); // e_version WriteWord(0); // e_entry, no entry point in .o file WriteWord(0); // e_phoff, no program header for .o - WriteWord(SectionDataSize + (is64Bit() ? sizeof(ELF::Elf64_Ehdr) : - sizeof(ELF::Elf32_Ehdr))); // e_shoff = sec hdr table off in bytes + WriteWord(SectionHeaderOffset); // e_shoff = sec hdr table off in bytes // e_flags = whatever the target wants Write32(Asm.getELFHeaderEFlags()); @@ -481,43 +481,18 @@ void ELFObjectWriter::WriteHeader(const MCAssembler &Asm, Write16(ShstrtabIndex); } -uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &OrigData, +uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout) { - MCSymbolData *Data = &OrigData; - if (Data->isCommon() && Data->isExternal()) - return Data->getCommonAlignment(); - - const MCSymbol *Symbol = &Data->getSymbol(); - bool IsThumbFunc = OrigData.getFlags() & ELF_Other_ThumbFunc; + if (Data.isCommon() && Data.isExternal()) + return Data.getCommonAlignment(); - uint64_t Res = 0; - if (Symbol->isVariable()) { - const MCExpr *Expr = Symbol->getVariableValue(); - MCValue Value; - if (!Expr->EvaluateAsRelocatable(Value, &Layout)) - llvm_unreachable("Invalid expression"); + uint64_t Res; + if (!Layout.getSymbolOffset(&Data, Res)) + return 0; - assert(!Value.getSymB()); - - Res = Value.getConstant(); - - if (const MCSymbolRefExpr *A = Value.getSymA()) { - Symbol = &A->getSymbol(); - Data = &Layout.getAssembler().getSymbolData(*Symbol); - } else { - Symbol = 0; - Data = 0; - } - } - - if (IsThumbFunc) + if (Layout.getAssembler().isThumbFunc(&Data.getSymbol())) Res |= 1; - if (!Symbol || !Symbol->isInSection()) - return Res; - - Res += Layout.getSymbolOffset(Data); - return Res; } @@ -526,15 +501,17 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm, // The presence of symbol versions causes undefined symbols and // versions declared with @@@ to be renamed. - for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), - ie = Asm.symbol_end(); it != ie; ++it) { - const MCSymbol &Alias = it->getSymbol(); - const MCSymbol &Symbol = Alias.AliasedSymbol(); - MCSymbolData &SD = Asm.getSymbolData(Symbol); + for (MCSymbolData &OriginalData : Asm.symbols()) { + const MCSymbol &Alias = OriginalData.getSymbol(); // Not an alias. - if (&Symbol == &Alias) + if (!Alias.isVariable()) continue; + auto *Ref = dyn_cast(Alias.getVariableValue()); + if (!Ref) + continue; + const MCSymbol &Symbol = Ref->getSymbol(); + MCSymbolData &SD = Asm.getSymbolData(Symbol); StringRef AliasName = Alias.getName(); size_t Pos = AliasName.find('@'); @@ -543,8 +520,8 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm, // Aliases defined with .symvar copy the binding from the symbol they alias. // This is the first place we are able to copy this information. - it->setExternal(SD.isExternal()); - MCELF::SetBinding(*it, MCELF::GetBinding(SD)); + OriginalData.setExternal(SD.isExternal()); + MCELF::SetBinding(OriginalData, MCELF::GetBinding(SD)); StringRef Rest = AliasName.substr(Pos); if (!Symbol.isUndefined() && !Rest.startswith("@@@")) @@ -594,26 +571,14 @@ static uint8_t mergeTypeForSet(uint8_t origType, uint8_t newType) { return Type; } -static const MCSymbol *getBaseSymbol(const MCAsmLayout &Layout, - const MCSymbol &Symbol) { - if (!Symbol.isVariable()) - return &Symbol; - - const MCExpr *Expr = Symbol.getVariableValue(); - MCValue Value; - if (!Expr->EvaluateAsRelocatable(Value, &Layout)) - llvm_unreachable("Invalid Expression"); - assert(!Value.getSymB()); - const MCSymbolRefExpr *A = Value.getSymA(); - if (!A) - return nullptr; - return getBaseSymbol(Layout, A->getSymbol()); -} - void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD, const MCAsmLayout &Layout) { MCSymbolData &OrigData = *MSD.SymbolData; - const MCSymbol *Base = getBaseSymbol(Layout, OrigData.getSymbol()); + assert((!OrigData.getFragment() || + (&OrigData.getFragment()->getParent()->getSection() == + &OrigData.getSymbol().getSection())) && + "The symbol's section doesn't match the fragment's symbol"); + const MCSymbol *Base = Layout.getBaseSymbol(OrigData.getSymbol()); // This has to be in sync with when computeSymbolTable uses SHN_ABS or // SHN_COMMON. @@ -627,8 +592,6 @@ void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD, BaseSD = &Layout.getAssembler().getSymbolData(*Base); Type = mergeTypeForSet(Type, MCELF::GetType(*BaseSD)); } - if (OrigData.getFlags() & ELF_Other_ThumbFunc) - Type = ELF::STT_FUNC; uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift); // Other and Visibility share the same byte with Visibility using the lower @@ -638,8 +601,6 @@ void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD, Other |= Visibility; uint64_t Value = SymbolValue(OrigData, Layout); - if (OrigData.getFlags() & ELF_Other_ThumbFunc) - Value |= 1; uint64_t Size = 0; const MCExpr *ESize = OrigData.getSize(); @@ -648,7 +609,7 @@ void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD, if (ESize) { int64_t Res; - if (!ESize->EvaluateAsAbsolute(Res, Layout)) + if (!ESize->evaluateKnownAbsolute(Res, Layout)) report_fatal_error("Size expression must be absolute."); Size = Res; } @@ -664,7 +625,6 @@ void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF, SectionIndexMapTy &SectionIndexMap) { // The string table must be emitted first because we need the index // into the string table for all the symbol names. - assert(StringTable.size() && "Missing string table"); // FIXME: Make sure the start of the symbol table is aligned. @@ -686,22 +646,6 @@ void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF, WriteSymbol(Writer, MSD, Layout); } - // Write out a symbol table entry for each regular section. - for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; - ++i) { - const MCSectionELF &Section = - static_cast(i->getSection()); - if (Section.getType() == ELF::SHT_RELA || - Section.getType() == ELF::SHT_REL || - Section.getType() == ELF::SHT_STRTAB || - Section.getType() == ELF::SHT_SYMTAB || - Section.getType() == ELF::SHT_SYMTAB_SHNDX) - continue; - Writer.writeSymbol(0, ELF::STT_SECTION, 0, 0, ELF::STV_DEFAULT, - SectionIndexMap.lookup(&Section), false); - LastLocalSymbolIndex++; - } - for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) { ELFSymbolData &MSD = ExternalSymbolData[i]; MCSymbolData &Data = *MSD.SymbolData; @@ -725,7 +669,8 @@ void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF, // It is always valid to create a relocation with a symbol. It is preferable // to use a relocation with a section if that is possible. Using the section // allows us to omit some local symbols from the symbol table. -bool ELFObjectWriter::shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA, +bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm, + const MCSymbolRefExpr *RefA, const MCSymbolData *SD, uint64_t C, unsigned Type) const { @@ -804,23 +749,52 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA, } // Most TLS relocations use a got, so they need the symbol. Even those that - // are just an offset (@tpoff), require a symbol in some linkers (gold, - // but not bfd ld). + // are just an offset (@tpoff), require a symbol in gold versions before + // 5efeedf61e4fe720fd3e9a08e6c91c10abb66d42 (2014-09-26) which fixed + // http://sourceware.org/PR16773. if (Flags & ELF::SHF_TLS) return true; - if (TargetObjectWriter->needsRelocateWithSymbol(Type)) + // If the symbol is a thumb function the final relocation must set the lowest + // bit. With a symbol that is done by just having the symbol have that bit + // set, so we would lose the bit if we relocated with the section. + // FIXME: We could use the section but add the bit to the relocation value. + if (Asm.isThumbFunc(&Sym)) + return true; + + if (TargetObjectWriter->needsRelocateWithSymbol(*SD, Type)) return true; return false; } -void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, +static const MCSymbol *getWeakRef(const MCSymbolRefExpr &Ref) { + const MCSymbol &Sym = Ref.getSymbol(); + + if (Ref.getKind() == MCSymbolRefExpr::VK_WEAKREF) + return &Sym; + + if (!Sym.isVariable()) + return nullptr; + + const MCExpr *Expr = Sym.getVariableValue(); + const auto *Inner = dyn_cast(Expr); + if (!Inner) + return nullptr; + + if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF) + return &Inner->getSymbol(); + return nullptr; +} + +static bool isWeak(const MCSymbolData &D) { + return D.getFlags() & ELF_STB_Weak || MCELF::GetType(D) == ELF::STT_GNU_IFUNC; +} + +void ELFObjectWriter::RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, - const MCFixup &Fixup, - MCValue Target, - bool &IsPCRel, - uint64_t &FixedValue) { + const MCFixup &Fixup, MCValue Target, + bool &IsPCRel, uint64_t &FixedValue) { const MCSectionData *FixupSection = Fragment->getParent(); uint64_t C = Target.getConstant(); uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); @@ -856,6 +830,10 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, Fixup.getLoc(), "Cannot represent a difference across sections"); const MCSymbolData &SymBD = Asm.getSymbolData(SymB); + if (::isWeak(SymBD)) + Asm.getContext().FatalError( + Fixup.getLoc(), "Cannot represent a subtraction with a weak symbol"); + uint64_t SymBOffset = Layout.getSymbolOffset(&SymBD); uint64_t K = SymBOffset - FixupOffset; IsPCRel = true; @@ -868,7 +846,7 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, const MCSymbolData *SymAD = SymA ? &Asm.getSymbolData(*SymA) : nullptr; unsigned Type = GetRelocType(Target, Fixup, IsPCRel); - bool RelocateWithSymbol = shouldRelocateWithSymbol(RefA, SymAD, C, Type); + bool RelocateWithSymbol = shouldRelocateWithSymbol(Asm, RefA, SymAD, C, Type); if (!RelocateWithSymbol && SymA && !SymA->isUndefined()) C += Layout.getSymbolOffset(SymAD); @@ -889,8 +867,11 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, if (!RelocateWithSymbol) { const MCSection *SecA = (SymA && !SymA->isUndefined()) ? &SymA->getSection() : nullptr; - const MCSectionData *SecAD = SecA ? &Asm.getSectionData(*SecA) : nullptr; - ELFRelocationEntry Rec(FixupOffset, SecAD, Type, Addend); + auto *ELFSec = cast_or_null(SecA); + MCSymbol *SectionSymbol = + ELFSec ? Asm.getContext().getOrCreateSectionSymbol(*ELFSec) + : nullptr; + ELFRelocationEntry Rec(FixupOffset, SectionSymbol, Type, Addend); Relocations[FixupSection].push_back(Rec); return; } @@ -899,8 +880,8 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, if (const MCSymbol *R = Renames.lookup(SymA)) SymA = R; - if (RefA->getKind() == MCSymbolRefExpr::VK_WEAKREF) - WeakrefUsedInReloc.insert(SymA); + if (const MCSymbol *WeakRef = getWeakRef(*RefA)) + WeakrefUsedInReloc.insert(WeakRef); else UsedInReloc.insert(SymA); } @@ -913,13 +894,13 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, uint64_t ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm, const MCSymbol *S) { - MCSymbolData &SD = Asm.getSymbolData(*S); + const MCSymbolData &SD = Asm.getSymbolData(*S); return SD.getIndex(); } -bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm, - const MCSymbolData &Data, - bool Used, bool Renamed) { +bool ELFObjectWriter::isInSymtab(const MCAsmLayout &Layout, + const MCSymbolData &Data, bool Used, + bool Renamed) { const MCSymbol &Symbol = Data.getSymbol(); if (Symbol.isVariable()) { const MCExpr *Expr = Symbol.getVariableValue(); @@ -938,9 +919,11 @@ bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm, if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_") return true; - const MCSymbol &A = Symbol.AliasedSymbol(); - if (Symbol.isVariable() && !A.isVariable() && A.isUndefined()) - return false; + if (Symbol.isVariable()) { + const MCSymbol *Base = Layout.getBaseSymbol(Symbol); + if (Base && Base->isUndefined()) + return false; + } bool IsGlobal = MCELF::GetBinding(Data) == ELF::STB_GLOBAL; if (!Symbol.isVariable() && Symbol.isUndefined() && !IsGlobal) @@ -952,27 +935,22 @@ bool ELFObjectWriter::isInSymtab(const MCAssembler &Asm, return true; } -bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isSignature, - bool isUsedInReloc) { +bool ELFObjectWriter::isLocal(const MCSymbolData &Data, bool isUsedInReloc) { if (Data.isExternal()) return false; const MCSymbol &Symbol = Data.getSymbol(); - const MCSymbol &RefSymbol = Symbol.AliasedSymbol(); - - if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) { - if (isSignature && !isUsedInReloc) - return true; + if (Symbol.isDefined()) + return true; + if (isUsedInReloc) return false; - } return true; } -void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm, - SectionIndexMapTy &SectionIndexMap, - const RelMapTy &RelMap) { +void ELFObjectWriter::computeIndexMap(MCAssembler &Asm, + SectionIndexMapTy &SectionIndexMap) { unsigned Index = 1; for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { @@ -985,24 +963,26 @@ void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm, for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { + const MCSectionData &SD = *it; const MCSectionELF &Section = - static_cast(it->getSection()); + static_cast(SD.getSection()); if (Section.getType() == ELF::SHT_GROUP || Section.getType() == ELF::SHT_REL || Section.getType() == ELF::SHT_RELA) continue; SectionIndexMap[&Section] = Index++; - const MCSectionELF *RelSection = RelMap.lookup(&Section); - if (RelSection) + if (MCSectionData *RelSD = createRelocationSection(Asm, SD)) { + const MCSectionELF *RelSection = + static_cast(&RelSD->getSection()); SectionIndexMap[RelSection] = Index++; + } } } -void -ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, - const SectionIndexMapTy &SectionIndexMap, - RevGroupMapTy RevGroupMap, - unsigned NumRegularSections) { +void ELFObjectWriter::computeSymbolTable( + MCAssembler &Asm, const MCAsmLayout &Layout, + const SectionIndexMapTy &SectionIndexMap, + const RevGroupMapTy &RevGroupMap) { // FIXME: Is this the correct place to do this? // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed? if (NeedsGOT) { @@ -1013,67 +993,45 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, MCELF::SetBinding(Data, ELF::STB_GLOBAL); } - // Index 0 is always the empty string. - StringMap StringIndexMap; - StringTable += '\x00'; - - // FIXME: We could optimize suffixes in strtab in the same way we - // optimize them in shstrtab. - - for (MCAssembler::const_file_name_iterator it = Asm.file_names_begin(), - ie = Asm.file_names_end(); - it != ie; - ++it) { - StringRef Name = *it; - uint64_t &Entry = StringIndexMap[Name]; - if (!Entry) { - Entry = StringTable.size(); - StringTable += Name; - StringTable += '\x00'; - } - FileSymbolData.push_back(Entry); - } - // Add the data for the symbols. - for (MCAssembler::symbol_iterator it = Asm.symbol_begin(), - ie = Asm.symbol_end(); it != ie; ++it) { - const MCSymbol &Symbol = it->getSymbol(); + for (MCSymbolData &SD : Asm.symbols()) { + const MCSymbol &Symbol = SD.getSymbol(); bool Used = UsedInReloc.count(&Symbol); bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol); bool isSignature = RevGroupMap.count(&Symbol); - if (!isInSymtab(Asm, *it, + if (!isInSymtab(Layout, SD, Used || WeakrefUsed || isSignature, Renames.count(&Symbol))) continue; ELFSymbolData MSD; - MSD.SymbolData = it; - const MCSymbol *BaseSymbol = getBaseSymbol(Layout, Symbol); + MSD.SymbolData = &SD; + const MCSymbol *BaseSymbol = Layout.getBaseSymbol(Symbol); // Undefined symbols are global, but this is the first place we // are able to set it. - bool Local = isLocal(*it, isSignature, Used); - if (!Local && MCELF::GetBinding(*it) == ELF::STB_LOCAL) { + bool Local = isLocal(SD, Used); + if (!Local && MCELF::GetBinding(SD) == ELF::STB_LOCAL) { assert(BaseSymbol); - MCSymbolData &SD = Asm.getSymbolData(*BaseSymbol); - MCELF::SetBinding(*it, ELF::STB_GLOBAL); + MCSymbolData &BaseData = Asm.getSymbolData(*BaseSymbol); MCELF::SetBinding(SD, ELF::STB_GLOBAL); + MCELF::SetBinding(BaseData, ELF::STB_GLOBAL); } if (!BaseSymbol) { MSD.SectionIndex = ELF::SHN_ABS; - } else if (it->isCommon()) { + } else if (SD.isCommon()) { assert(!Local); MSD.SectionIndex = ELF::SHN_COMMON; } else if (BaseSymbol->isUndefined()) { if (isSignature && !Used) - MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]); + MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap.lookup(&Symbol)); else MSD.SectionIndex = ELF::SHN_UNDEF; if (!Used && WeakrefUsed) - MCELF::SetBinding(*it, ELF::STB_WEAK); + MCELF::SetBinding(SD, ELF::STB_WEAK); } else { const MCSectionELF &Section = static_cast(BaseSymbol->getSection()); @@ -1081,26 +1039,49 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, assert(MSD.SectionIndex && "Invalid section index!"); } - // The @@@ in symbol version is replaced with @ in undefined symbols and - // @@ in defined ones. + // The @@@ in symbol version is replaced with @ in undefined symbols and @@ + // in defined ones. + // + // FIXME: All name handling should be done before we get to the writer, + // including dealing with GNU-style version suffixes. Fixing this isn't + // trivial. + // + // We thus have to be careful to not perform the symbol version replacement + // blindly: + // + // The ELF format is used on Windows by the MCJIT engine. Thus, on + // Windows, the ELFObjectWriter can encounter symbols mangled using the MS + // Visual Studio C++ name mangling scheme. Symbols mangled using the MSVC + // C++ name mangling can legally have "@@@" as a sub-string. In that case, + // the EFLObjectWriter should not interpret the "@@@" sub-string as + // specifying GNU-style symbol versioning. The ELFObjectWriter therefore + // checks for the MSVC C++ name mangling prefix which is either "?", "@?", + // "__imp_?" or "__imp_@?". + // + // It would have been interesting to perform the MS mangling prefix check + // only when the target triple is of the form *-pc-windows-elf. But, it + // seems that this information is not easily accessible from the + // ELFObjectWriter. StringRef Name = Symbol.getName(); - SmallString<32> Buf; - - size_t Pos = Name.find("@@@"); - if (Pos != StringRef::npos) { - Buf += Name.substr(0, Pos); - unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1; - Buf += Name.substr(Pos + Skip); - Name = Buf; + if (!Name.startswith("?") && !Name.startswith("@?") && + !Name.startswith("__imp_?") && !Name.startswith("__imp_@?")) { + // This symbol isn't following the MSVC C++ name mangling convention. We + // can thus safely interpret the @@@ in symbol names as specifying symbol + // versioning. + SmallString<32> Buf; + size_t Pos = Name.find("@@@"); + if (Pos != StringRef::npos) { + Buf += Name.substr(0, Pos); + unsigned Skip = MSD.SectionIndex == ELF::SHN_UNDEF ? 2 : 1; + Buf += Name.substr(Pos + Skip); + Name = Buf; + } } - uint64_t &Entry = StringIndexMap[Name]; - if (!Entry) { - Entry = StringTable.size(); - StringTable += Name; - StringTable += '\x00'; - } - MSD.StringIndex = Entry; + // Sections have their own string table + if (MCELF::GetType(SD) != ELF::STT_SECTION) + MSD.Name = StrTabBuilder.add(Name); + if (MSD.SectionIndex == ELF::SHN_UNDEF) UndefinedSymbolData.push_back(MSD); else if (Local) @@ -1109,6 +1090,23 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, ExternalSymbolData.push_back(MSD); } + for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i) + StrTabBuilder.add(*i); + + StrTabBuilder.finalize(StringTableBuilder::ELF); + + for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i) + FileSymbolData.push_back(StrTabBuilder.getOffset(*i)); + + for (ELFSymbolData &MSD : LocalSymbolData) + MSD.StringIndex = MCELF::GetType(*MSD.SymbolData) == ELF::STT_SECTION + ? 0 + : StrTabBuilder.getOffset(MSD.Name); + for (ELFSymbolData &MSD : ExternalSymbolData) + MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name); + for (ELFSymbolData& MSD : UndefinedSymbolData) + MSD.StringIndex = StrTabBuilder.getOffset(MSD.Name); + // Symbols are required to be in lexicographic order. array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end()); array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end()); @@ -1120,70 +1118,203 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) LocalSymbolData[i].SymbolData->setIndex(Index++); - Index += NumRegularSections; - for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) ExternalSymbolData[i].SymbolData->setIndex(Index++); for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) UndefinedSymbolData[i].SymbolData->setIndex(Index++); } -void ELFObjectWriter::CreateRelocationSections(MCAssembler &Asm, - MCAsmLayout &Layout, - RelMapTy &RelMap) { - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - const MCSectionData &SD = *it; - if (Relocations[&SD].empty()) - continue; +MCSectionData * +ELFObjectWriter::createRelocationSection(MCAssembler &Asm, + const MCSectionData &SD) { + if (Relocations[&SD].empty()) + return nullptr; - MCContext &Ctx = Asm.getContext(); - const MCSectionELF &Section = - static_cast(SD.getSection()); + MCContext &Ctx = Asm.getContext(); + const MCSectionELF &Section = + static_cast(SD.getSection()); - const StringRef SectionName = Section.getSectionName(); - std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel"; - RelaSectionName += SectionName; + const StringRef SectionName = Section.getSectionName(); + std::string RelaSectionName = hasRelocationAddend() ? ".rela" : ".rel"; + RelaSectionName += SectionName; - unsigned EntrySize; - if (hasRelocationAddend()) - EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela); - else - EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel); + unsigned EntrySize; + if (hasRelocationAddend()) + EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rela) : sizeof(ELF::Elf32_Rela); + else + EntrySize = is64Bit() ? sizeof(ELF::Elf64_Rel) : sizeof(ELF::Elf32_Rel); + + unsigned Flags = 0; + if (Section.getFlags() & ELF::SHF_GROUP) + Flags = ELF::SHF_GROUP; - unsigned Flags = 0; - StringRef Group = ""; - if (Section.getFlags() & ELF::SHF_GROUP) { - Flags = ELF::SHF_GROUP; - Group = Section.getGroup()->getName(); + const MCSectionELF *RelaSection = Ctx.createELFRelSection( + RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL, + Flags, EntrySize, Section.getGroup(), &Section); + return &Asm.getOrCreateSectionData(*RelaSection); +} + +static SmallVector +getUncompressedData(MCAsmLayout &Layout, + MCSectionData::FragmentListType &Fragments) { + SmallVector UncompressedData; + for (const MCFragment &F : Fragments) { + const SmallVectorImpl *Contents; + switch (F.getKind()) { + case MCFragment::FT_Data: + Contents = &cast(F).getContents(); + break; + case MCFragment::FT_Dwarf: + Contents = &cast(F).getContents(); + break; + case MCFragment::FT_DwarfFrame: + Contents = &cast(F).getContents(); + break; + default: + llvm_unreachable( + "Not expecting any other fragment types in a debug_* section"); } + UncompressedData.append(Contents->begin(), Contents->end()); + } + return UncompressedData; +} + +// Include the debug info compression header: +// "ZLIB" followed by 8 bytes representing the uncompressed size of the section, +// useful for consumers to preallocate a buffer to decompress into. +static bool +prependCompressionHeader(uint64_t Size, + SmallVectorImpl &CompressedContents) { + const StringRef Magic = "ZLIB"; + if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size()) + return false; + if (sys::IsLittleEndianHost) + sys::swapByteOrder(Size); + CompressedContents.insert(CompressedContents.begin(), + Magic.size() + sizeof(Size), 0); + std::copy(Magic.begin(), Magic.end(), CompressedContents.begin()); + std::copy(reinterpret_cast(&Size), + reinterpret_cast(&Size + 1), + CompressedContents.begin() + Magic.size()); + return true; +} + +// Return a single fragment containing the compressed contents of the whole +// section. Null if the section was not compressed for any reason. +static std::unique_ptr +getCompressedFragment(MCAsmLayout &Layout, + MCSectionData::FragmentListType &Fragments) { + std::unique_ptr CompressedFragment(new MCDataFragment()); + + // Gather the uncompressed data from all the fragments, recording the + // alignment fragment, if seen, and any fixups. + SmallVector UncompressedData = + getUncompressedData(Layout, Fragments); - const MCSectionELF *RelaSection = - Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ? - ELF::SHT_RELA : ELF::SHT_REL, Flags, - SectionKind::getReadOnly(), - EntrySize, Group); - RelMap[&Section] = RelaSection; - Asm.getOrCreateSectionData(*RelaSection); + SmallVectorImpl &CompressedContents = CompressedFragment->getContents(); + + zlib::Status Success = zlib::compress( + StringRef(UncompressedData.data(), UncompressedData.size()), + CompressedContents); + if (Success != zlib::StatusOK) + return nullptr; + + if (!prependCompressionHeader(UncompressedData.size(), CompressedContents)) + return nullptr; + + return CompressedFragment; +} + +typedef DenseMap> +DefiningSymbolMap; + +static void UpdateSymbols(const MCAsmLayout &Layout, + const std::vector &Symbols, + MCFragment &NewFragment) { + for (MCSymbolData *Sym : Symbols) { + Sym->setOffset(Sym->getOffset() + + Layout.getFragmentOffset(Sym->getFragment())); + Sym->setFragment(&NewFragment); } } -void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout, - const RelMapTy &RelMap) { - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - const MCSectionData &SD = *it; +static void CompressDebugSection(MCAssembler &Asm, MCAsmLayout &Layout, + const DefiningSymbolMap &DefiningSymbols, + const MCSectionELF &Section, + MCSectionData &SD) { + StringRef SectionName = Section.getSectionName(); + MCSectionData::FragmentListType &Fragments = SD.getFragmentList(); + + std::unique_ptr CompressedFragment = + getCompressedFragment(Layout, Fragments); + + // Leave the section as-is if the fragments could not be compressed. + if (!CompressedFragment) + return; + + // Update the fragment+offsets of any symbols referring to fragments in this + // section to refer to the new fragment. + auto I = DefiningSymbols.find(&SD); + if (I != DefiningSymbols.end()) + UpdateSymbols(Layout, I->second, *CompressedFragment); + + // Invalidate the layout for the whole section since it will have new and + // different fragments now. + Layout.invalidateFragmentsFrom(&Fragments.front()); + Fragments.clear(); + + // Complete the initialization of the new fragment + CompressedFragment->setParent(&SD); + CompressedFragment->setLayoutOrder(0); + Fragments.push_back(CompressedFragment.release()); + + // Rename from .debug_* to .zdebug_* + Asm.getContext().renameELFSection(&Section, + (".z" + SectionName.drop_front(1)).str()); +} + +void ELFObjectWriter::CompressDebugSections(MCAssembler &Asm, + MCAsmLayout &Layout) { + if (!Asm.getContext().getAsmInfo()->compressDebugSections()) + return; + + DefiningSymbolMap DefiningSymbols; + + for (MCSymbolData &SD : Asm.symbols()) + if (MCFragment *F = SD.getFragment()) + DefiningSymbols[F->getParent()].push_back(&SD); + + for (MCSectionData &SD : Asm) { const MCSectionELF &Section = - static_cast(SD.getSection()); + static_cast(SD.getSection()); + StringRef SectionName = Section.getSectionName(); + + // Compressing debug_frame requires handling alignment fragments which is + // more work (possibly generalizing MCAssembler.cpp:writeFragment to allow + // for writing to arbitrary buffers) for little benefit. + if (!SectionName.startswith(".debug_") || SectionName == ".debug_frame") + continue; + + CompressDebugSection(Asm, Layout, DefiningSymbols, Section, SD); + } +} + +void ELFObjectWriter::WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) { + for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { + MCSectionData &RelSD = *it; + const MCSectionELF &RelSection = + static_cast(RelSD.getSection()); - const MCSectionELF *RelaSection = RelMap.lookup(&Section); - if (!RelaSection) + unsigned Type = RelSection.getType(); + if (Type != ELF::SHT_REL && Type != ELF::SHT_RELA) continue; - MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection); - RelaSD.setAlignment(is64Bit() ? 8 : 4); - MCDataFragment *F = new MCDataFragment(&RelaSD); - WriteRelocationsFragment(Asm, F, &*it); + const MCSectionELF *Section = RelSection.getAssociatedSection(); + MCSectionData &SD = Asm.getOrCreateSectionData(*Section); + RelSD.setAlignment(is64Bit() ? 8 : 4); + + MCDataFragment *F = new MCDataFragment(&RelSD); + WriteRelocationsFragment(Asm, F, &SD); } } @@ -1215,7 +1346,8 @@ static int cmpRel(const ELFRelocationEntry *AP, const ELFRelocationEntry *BP) { return B.Offset - A.Offset; if (B.Type != A.Type) return A.Type - B.Type; - llvm_unreachable("ELFRelocs might be unstable!"); + //llvm_unreachable("ELFRelocs might be unstable!"); + return 0; } static void sortRelocs(const MCAssembler &Asm, @@ -1232,18 +1364,8 @@ void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm, for (unsigned i = 0, e = Relocs.size(); i != e; ++i) { const ELFRelocationEntry &Entry = Relocs[e - i - 1]; - - unsigned Index; - if (Entry.UseSymbol) { - Index = getSymbolIndexInSymbolTable(Asm, Entry.Symbol); - } else { - const MCSectionData *Sec = Entry.Section; - if (Sec) - Index = Sec->getOrdinal() + FileSymbolData.size() + - LocalSymbolData.size() + 1; - else - Index = 0; - } + unsigned Index = + Entry.Symbol ? getSymbolIndexInSymbolTable(Asm, Entry.Symbol) : 0; if (is64Bit()) { write(*F, Entry.Offset); @@ -1274,27 +1396,8 @@ void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm, } } -static int compareBySuffix(const MCSectionELF *const *a, - const MCSectionELF *const *b) { - const StringRef &NameA = (*a)->getSectionName(); - const StringRef &NameB = (*b)->getSectionName(); - const unsigned sizeA = NameA.size(); - const unsigned sizeB = NameB.size(); - const unsigned len = std::min(sizeA, sizeB); - for (unsigned int i = 0; i < len; ++i) { - char ca = NameA[sizeA - i - 1]; - char cb = NameB[sizeB - i - 1]; - if (ca != cb) - return cb - ca; - } - - return sizeB - sizeA; -} - -void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm, - MCAsmLayout &Layout, - SectionIndexMapTy &SectionIndexMap, - const RelMapTy &RelMap) { +void ELFObjectWriter::CreateMetadataSections( + MCAssembler &Asm, MCAsmLayout &Layout, SectionIndexMapTy &SectionIndexMap) { MCContext &Ctx = Asm.getContext(); MCDataFragment *F; @@ -1302,90 +1405,52 @@ void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm, // We construct .shstrtab, .symtab and .strtab in this order to match gnu as. const MCSectionELF *ShstrtabSection = - Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0, - SectionKind::getReadOnly()); + Ctx.getELFSection(".shstrtab", ELF::SHT_STRTAB, 0); MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection); ShstrtabSD.setAlignment(1); + ShstrtabIndex = SectionIndexMap.size() + 1; + SectionIndexMap[ShstrtabSection] = ShstrtabIndex; const MCSectionELF *SymtabSection = Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, - SectionKind::getReadOnly(), EntrySize, ""); MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection); SymtabSD.setAlignment(is64Bit() ? 8 : 4); + SymbolTableIndex = SectionIndexMap.size() + 1; + SectionIndexMap[SymtabSection] = SymbolTableIndex; const MCSectionELF *StrtabSection; - StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0, - SectionKind::getReadOnly()); + StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0); MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection); StrtabSD.setAlignment(1); - - ComputeIndexMap(Asm, SectionIndexMap, RelMap); - - ShstrtabIndex = SectionIndexMap.lookup(ShstrtabSection); - SymbolTableIndex = SectionIndexMap.lookup(SymtabSection); - StringTableIndex = SectionIndexMap.lookup(StrtabSection); + StringTableIndex = SectionIndexMap.size() + 1; + SectionIndexMap[StrtabSection] = StringTableIndex; // Symbol table F = new MCDataFragment(&SymtabSD); WriteSymbolTable(F, Asm, Layout, SectionIndexMap); F = new MCDataFragment(&StrtabSD); - F->getContents().append(StringTable.begin(), StringTable.end()); + F->getContents().append(StrTabBuilder.data().begin(), + StrTabBuilder.data().end()); F = new MCDataFragment(&ShstrtabSD); - std::vector Sections; - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { + // Section header string table. + for (auto it = Asm.begin(), ie = Asm.end(); it != ie; ++it) { const MCSectionELF &Section = static_cast(it->getSection()); - Sections.push_back(&Section); - } - array_pod_sort(Sections.begin(), Sections.end(), compareBySuffix); - - // Section header string table. - // - // The first entry of a string table holds a null character so skip - // section 0. - uint64_t Index = 1; - F->getContents().push_back('\x00'); - - for (unsigned int I = 0, E = Sections.size(); I != E; ++I) { - const MCSectionELF &Section = *Sections[I]; - - StringRef Name = Section.getSectionName(); - if (I != 0) { - StringRef PreviousName = Sections[I - 1]->getSectionName(); - if (PreviousName.endswith(Name)) { - SectionStringTableIndex[&Section] = Index - Name.size() - 1; - continue; - } - } - // Remember the index into the string table so we can write it - // into the sh_name field of the section header table. - SectionStringTableIndex[&Section] = Index; - - Index += Name.size() + 1; - F->getContents().append(Name.begin(), Name.end()); - F->getContents().push_back('\x00'); + ShStrTabBuilder.add(Section.getSectionName()); } + ShStrTabBuilder.finalize(StringTableBuilder::ELF); + F->getContents().append(ShStrTabBuilder.data().begin(), + ShStrTabBuilder.data().end()); } -void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, - MCAsmLayout &Layout, - GroupMapTy &GroupMap, - RevGroupMapTy &RevGroupMap, - SectionIndexMapTy &SectionIndexMap, - const RelMapTy &RelMap) { - // Create the .note.GNU-stack section if needed. +void ELFObjectWriter::createIndexedSections( + MCAssembler &Asm, MCAsmLayout &Layout, GroupMapTy &GroupMap, + RevGroupMapTy &RevGroupMap, SectionIndexMapTy &SectionIndexMap) { MCContext &Ctx = Asm.getContext(); - if (Asm.getNoExecStack()) { - const MCSectionELF *GnuStackSection = - Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0, - SectionKind::getReadOnly()); - Asm.getOrCreateSectionData(*GnuStackSection); - } // Build the groups for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); @@ -1408,7 +1473,7 @@ void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, GroupMap[Group] = SignatureSymbol; } - ComputeIndexMap(Asm, SectionIndexMap, RelMap); + computeIndexMap(Asm, SectionIndexMap); // Add sections to the groups for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); @@ -1426,7 +1491,7 @@ void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, } } -void ELFObjectWriter::WriteSection(MCAssembler &Asm, +void ELFObjectWriter::writeSection(MCAssembler &Asm, const SectionIndexMapTy &SectionIndexMap, uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size, @@ -1436,30 +1501,19 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm, uint64_t sh_info = 0; switch(Section.getType()) { + default: + // Nothing to do. + break; + case ELF::SHT_DYNAMIC: - sh_link = SectionStringTableIndex[&Section]; - sh_info = 0; + sh_link = ShStrTabBuilder.getOffset(Section.getSectionName()); break; case ELF::SHT_REL: case ELF::SHT_RELA: { - const MCSectionELF *SymtabSection; - const MCSectionELF *InfoSection; - SymtabSection = Asm.getContext().getELFSection(".symtab", ELF::SHT_SYMTAB, - 0, - SectionKind::getReadOnly()); - sh_link = SectionIndexMap.lookup(SymtabSection); + sh_link = SymbolTableIndex; assert(sh_link && ".symtab not found"); - - // Remove ".rel" and ".rela" prefixes. - unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5; - StringRef SectionName = Section.getSectionName().substr(SecNameLen); - StringRef GroupName = - Section.getGroup() ? Section.getGroup()->getName() : ""; - - InfoSection = Asm.getContext().getELFSection(SectionName, ELF::SHT_PROGBITS, - 0, SectionKind::getReadOnly(), - 0, GroupName); + const MCSectionELF *InfoSection = Section.getAssociatedSection(); sh_info = SectionIndexMap.lookup(InfoSection); break; } @@ -1474,51 +1528,18 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm, sh_link = SymbolTableIndex; break; - case ELF::SHT_PROGBITS: - case ELF::SHT_STRTAB: - case ELF::SHT_NOBITS: - case ELF::SHT_NOTE: - case ELF::SHT_NULL: - case ELF::SHT_ARM_ATTRIBUTES: - case ELF::SHT_INIT_ARRAY: - case ELF::SHT_FINI_ARRAY: - case ELF::SHT_PREINIT_ARRAY: - case ELF::SHT_X86_64_UNWIND: - case ELF::SHT_MIPS_REGINFO: - case ELF::SHT_MIPS_OPTIONS: - // Nothing to do. - break; - case ELF::SHT_GROUP: sh_link = SymbolTableIndex; sh_info = GroupSymbolIndex; break; - - default: - assert(0 && "FIXME: sh_type value not supported!"); - break; } if (TargetObjectWriter->getEMachine() == ELF::EM_ARM && - Section.getType() == ELF::SHT_ARM_EXIDX) { - StringRef SecName(Section.getSectionName()); - if (SecName == ".ARM.exidx") { - sh_link = SectionIndexMap.lookup( - Asm.getContext().getELFSection(".text", - ELF::SHT_PROGBITS, - ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, - SectionKind::getText())); - } else if (SecName.startswith(".ARM.exidx")) { - StringRef GroupName = - Section.getGroup() ? Section.getGroup()->getName() : ""; - sh_link = SectionIndexMap.lookup(Asm.getContext().getELFSection( - SecName.substr(sizeof(".ARM.exidx") - 1), ELF::SHT_PROGBITS, - ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, SectionKind::getText(), 0, - GroupName)); - } - } + Section.getType() == ELF::SHT_ARM_EXIDX) + sh_link = SectionIndexMap.lookup(Section.getAssociatedSection()); - WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(), + WriteSecHdrEntry(ShStrTabBuilder.getOffset(Section.getSectionName()), + Section.getType(), Section.getFlags(), 0, Offset, Size, sh_link, sh_info, Alignment, Section.getEntrySize()); } @@ -1573,11 +1594,10 @@ void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm, } } -void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm, - const GroupMapTy &GroupMap, - const MCAsmLayout &Layout, - const SectionIndexMapTy &SectionIndexMap, - const SectionOffsetMapTy &SectionOffsetMap) { +void ELFObjectWriter::writeSectionHeader( + MCAssembler &Asm, const GroupMapTy &GroupMap, const MCAsmLayout &Layout, + const SectionIndexMapTy &SectionIndexMap, + const SectionOffsetMapTy &SectionOffsetMap) { const unsigned NumSections = Asm.size() + 1; std::vector Sections; @@ -1608,9 +1628,9 @@ void ELFObjectWriter::WriteSectionHeader(MCAssembler &Asm, uint64_t Size = GetSectionAddressSize(Layout, SD); - WriteSection(Asm, SectionIndexMap, GroupSymbolIndex, - SectionOffsetMap.lookup(&Section), Size, - SD.getAlignment(), Section); + writeSection(Asm, SectionIndexMap, GroupSymbolIndex, + SectionOffsetMap.lookup(&Section), Size, SD.getAlignment(), + Section); } } @@ -1650,29 +1670,18 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm, RevGroupMapTy RevGroupMap; SectionIndexMapTy SectionIndexMap; - unsigned NumUserSections = Asm.size(); - - DenseMap RelMap; - CreateRelocationSections(Asm, const_cast(Layout), RelMap); - - const unsigned NumUserAndRelocSections = Asm.size(); - CreateIndexedSections(Asm, const_cast(Layout), GroupMap, - RevGroupMap, SectionIndexMap, RelMap); - const unsigned AllSections = Asm.size(); - const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections; - - unsigned NumRegularSections = NumUserSections + NumIndexedSections; + CompressDebugSections(Asm, const_cast(Layout)); + createIndexedSections(Asm, const_cast(Layout), GroupMap, + RevGroupMap, SectionIndexMap); // Compute symbol table information. - computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap, - NumRegularSections); + computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap); - WriteRelocations(Asm, const_cast(Layout), RelMap); + WriteRelocations(Asm, const_cast(Layout)); CreateMetadataSections(const_cast(Asm), const_cast(Layout), - SectionIndexMap, - RelMap); + SectionIndexMap); uint64_t NaturalAlignment = is64Bit() ? 8 : 4; uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) : @@ -1683,7 +1692,8 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm, ComputeSectionOrder(Asm, Sections); unsigned NumSections = Sections.size(); SectionOffsetMapTy SectionOffsetMap; - for (unsigned i = 0; i < NumRegularSections + 1; ++i) { + for (unsigned i = 0; i < NumSections; ++i) { + const MCSectionELF &Section = *Sections[i]; const MCSectionData &SD = Asm.getOrCreateSectionData(Section); @@ -1698,55 +1708,34 @@ void ELFObjectWriter::WriteObject(MCAssembler &Asm, FileOff = RoundUpToAlignment(FileOff, NaturalAlignment); - const unsigned SectionHeaderOffset = FileOff - HeaderSize; - - uint64_t SectionHeaderEntrySize = is64Bit() ? - sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr); - FileOff += (NumSections + 1) * SectionHeaderEntrySize; - - for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) { - const MCSectionELF &Section = *Sections[i]; - const MCSectionData &SD = Asm.getOrCreateSectionData(Section); - - FileOff = RoundUpToAlignment(FileOff, SD.getAlignment()); - - // Remember the offset into the file for this section. - SectionOffsetMap[&Section] = FileOff; - - // Get the size of the section in the output file (including padding). - FileOff += GetSectionFileSize(Layout, SD); - } + const unsigned SectionHeaderOffset = FileOff; // Write out the ELF header ... WriteHeader(Asm, SectionHeaderOffset, NumSections + 1); - // ... then the regular sections ... - // + because of .shstrtab - for (unsigned i = 0; i < NumRegularSections + 1; ++i) + // ... then the sections ... + for (unsigned i = 0; i < NumSections; ++i) WriteDataSectionData(Asm, Layout, *Sections[i]); uint64_t Padding = OffsetToAlignment(OS.tell(), NaturalAlignment); WriteZeros(Padding); // ... then the section header table ... - WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, - SectionOffsetMap); - - // ... and then the remaining sections ... - for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) - WriteDataSectionData(Asm, Layout, *Sections[i]); + writeSectionHeader(Asm, GroupMap, Layout, SectionIndexMap, SectionOffsetMap); } -bool -ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, - const MCSymbolData &DataA, - const MCFragment &FB, - bool InSet, - bool IsPCRel) const { - if (DataA.getFlags() & ELF_STB_Weak || MCELF::GetType(DataA) == ELF::STT_GNU_IFUNC) +bool ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl( + const MCAssembler &Asm, const MCSymbolData &DataA, + const MCSymbolData *DataB, const MCFragment &FB, bool InSet, + bool IsPCRel) const { + if (!InSet && (::isWeak(DataA) || (DataB && ::isWeak(*DataB)))) return false; return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl( - Asm, DataA, FB,InSet, IsPCRel); + Asm, DataA, DataB, FB, InSet, IsPCRel); +} + +bool ELFObjectWriter::isWeak(const MCSymbolData &SD) const { + return ::isWeak(SD); } MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW,