X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FMC%2FELFObjectWriter.cpp;h=d77f03f5281aa8a41b19cd35c0bb808c37c72bda;hb=ad04f5db82d5433f9f5e134a9610f88ba1cdf810;hp=3bce12119206a09d93731ef086bf75b5d5f028c9;hpb=f2b88ce2fd0d204b981f2c6cc70f8112f563fd7c;p=oota-llvm.git diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp index 3bce1211920..d77f03f5281 100644 --- a/lib/MC/ELFObjectWriter.cpp +++ b/lib/MC/ELFObjectWriter.cpp @@ -28,7 +28,7 @@ #include "llvm/MC/MCObjectWriter.h" #include "llvm/MC/MCSectionELF.h" #include "llvm/MC/MCValue.h" -#include "llvm/Object/StringTableBuilder.h" +#include "llvm/MC/StringTableBuilder.h" #include "llvm/Support/Compression.h" #include "llvm/Support/Debug.h" #include "llvm/Support/Endian.h" @@ -81,23 +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 { @@ -137,6 +127,14 @@ class ELFObjectWriter : public MCObjectWriter { // Support lexicographic sorting. bool operator<(const ELFSymbolData &RHS) const { + 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; } }; @@ -246,7 +244,7 @@ class ELFObjectWriter : public MCObjectWriter { /// \param NumRegularSections - Number of non-relocation sections. void computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap, - RevGroupMapTy RevGroupMap, + const RevGroupMapTy &RevGroupMap, unsigned NumRegularSections); void ComputeIndexMap(MCAssembler &Asm, @@ -651,22 +649,6 @@ 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; @@ -770,8 +752,9 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm, } // 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; @@ -782,11 +765,30 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm, if (Asm.isThumbFunc(&Sym)) return true; - if (TargetObjectWriter->needsRelocateWithSymbol(Type)) + if (TargetObjectWriter->needsRelocateWithSymbol(*SD, Type)) return true; return false; } +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; +} + void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment, @@ -862,8 +864,11 @@ 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().GetOrCreateSymbol(ELFSec->getSectionName()) + : nullptr; + ELFRelocationEntry Rec(FixupOffset, SectionSymbol, Type, Addend); Relocations[FixupSection].push_back(Rec); return; } @@ -872,8 +877,8 @@ 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); } @@ -972,7 +977,7 @@ void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm, void ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap, - RevGroupMapTy RevGroupMap, + const RevGroupMapTy &RevGroupMap, unsigned NumRegularSections) { // FIXME: Is this the correct place to do this? // FIXME: Why is an undefined reference to _GLOBAL_OFFSET_TABLE_ needed? @@ -1018,7 +1023,7 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, 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) @@ -1041,7 +1046,10 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, Buf += Name.substr(Pos + Skip); Name = Buf; } - MSD.Name = StrTabBuilder.add(Name); + + // 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); @@ -1054,14 +1062,16 @@ ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout, for (auto i = Asm.file_names_begin(), e = Asm.file_names_end(); i != e; ++i) StrTabBuilder.add(*i); - StrTabBuilder.finalize(); + 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 = StrTabBuilder.getOffset(MSD.Name); - for (ELFSymbolData& MSD : ExternalSymbolData) + 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); @@ -1077,8 +1087,6 @@ 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) @@ -1160,7 +1168,7 @@ prependCompressionHeader(uint64_t Size, if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size()) return false; if (sys::IsLittleEndianHost) - Size = sys::SwapByteOrder(Size); + sys::swapByteOrder(Size); CompressedContents.insert(CompressedContents.begin(), Magic.size() + sizeof(Size), 0); std::copy(Magic.begin(), Magic.end(), CompressedContents.begin()); @@ -1334,18 +1342,8 @@ 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); @@ -1427,7 +1425,7 @@ void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm, static_cast(it->getSection()); ShStrTabBuilder.add(Section.getSectionName()); } - ShStrTabBuilder.finalize(); + ShStrTabBuilder.finalize(StringTableBuilder::ELF); F->getContents().append(ShStrTabBuilder.data().begin(), ShStrTabBuilder.data().end()); } @@ -1438,14 +1436,7 @@ void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm, RevGroupMapTy &RevGroupMap, SectionIndexMapTy &SectionIndexMap, const RelMapTy &RelMap) { - // Create the .note.GNU-stack section if needed. 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(); @@ -1546,6 +1537,7 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm, case ELF::SHT_X86_64_UNWIND: case ELF::SHT_MIPS_REGINFO: case ELF::SHT_MIPS_OPTIONS: + case ELF::SHT_MIPS_ABIFLAGS: // Nothing to do. break; @@ -1555,8 +1547,7 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm, break; default: - assert(0 && "FIXME: sh_type value not supported!"); - break; + llvm_unreachable("FIXME: sh_type value not supported!"); } if (TargetObjectWriter->getEMachine() == ELF::EM_ARM &&