#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 <vector>
using namespace llvm;
MCAssembler &Asm;
FragmentWriter &FWriter;
bool Is64Bit;
- SectionIndexMapTy &SectionIndexMap;
+ std::vector<const MCSectionELF *> &Sections;
// The symbol .symtab fragment we are writting to.
MCDataFragment *SymtabF;
public:
SymbolTableWriter(MCAssembler &Asm, FragmentWriter &FWriter, bool Is64Bit,
- SectionIndexMapTy &SectionIndexMap,
+ std::vector<const MCSectionELF *> &Sections,
MCDataFragment *SymtabF);
void writeSymbol(uint32_t name, uint8_t info, uint64_t value, uint64_t size,
uint8_t other, uint32_t shndx, bool Reserved);
};
-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.
- };
- 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) {}
-};
-
class ELFObjectWriter : public MCObjectWriter {
FragmentWriter FWriter;
bool Used, bool Renamed);
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,
- const MCSectionData &SD);
- static uint64_t GetSectionAddressSize(const MCAsmLayout &Layout,
- const MCSectionData &SD);
-
- void WriteDataSectionData(MCAssembler &Asm,
- 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.
+
+ void writeDataSectionData(MCAssembler &Asm, const MCAsmLayout &Layout,
+ const MCSectionData &SD);
+
+ /// 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;
}
};
llvm::DenseMap<const MCSectionData *, std::vector<ELFRelocationEntry>>
Relocations;
- DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
+ StringTableBuilder ShStrTabBuilder;
/// @}
/// @name Symbol Table Data
/// @{
- SmallString<256> StringTable;
+ StringTableBuilder StrTabBuilder;
std::vector<uint64_t> FileSymbolData;
std::vector<ELFSymbolData> LocalSymbolData;
std::vector<ELFSymbolData> ExternalSymbolData;
}
public:
- ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_ostream &_OS,
+ ELFObjectWriter(MCELFObjectTargetWriter *MOTW, raw_pwrite_stream &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())
}
void WriteHeader(const MCAssembler &Asm,
- uint64_t SectionDataSize,
unsigned NumberOfSections);
void WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
void WriteSymbolTable(MCDataFragment *SymtabF, MCAssembler &Asm,
const MCAsmLayout &Layout,
- SectionIndexMapTy &SectionIndexMap);
+ std::vector<const MCSectionELF *> &Sections);
- 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;
uint64_t getSymbolIndexInSymbolTable(const MCAssembler &Asm,
const MCSymbol *S);
- // Map from a group section to the signature symbol
- typedef DenseMap<const MCSectionELF*, const MCSymbol*> GroupMapTy;
- // Map from a signature symbol to the group section
- typedef DenseMap<const MCSymbol*, const MCSectionELF*> RevGroupMapTy;
- // Map from a section to the section with the relocations
- typedef DenseMap<const MCSectionELF*, const MCSectionELF*> RelMapTy;
- // Map from a section to its offset
- typedef DenseMap<const MCSectionELF*, uint64_t> SectionOffsetMapTy;
+ // Map from a signature symbol to the group section index
+ typedef DenseMap<const MCSymbol *, unsigned> RevGroupMapTy;
+ // Start and end offset of each section
+ typedef std::vector<std::pair<uint64_t, uint64_t>> SectionOffsetsTy;
/// Compute the symbol table data
///
/// \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,
+ void maybeAddToGroup(MCAssembler &Asm,
+ ArrayRef<const MCSectionELF *> Sections,
+ const RevGroupMapTy &RevGroupMap,
+ const MCSectionELF &Section, unsigned Index);
+
+ void computeIndexMap(MCAssembler &Asm,
+ std::vector<const MCSectionELF *> &Sections,
SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap);
+ const RevGroupMapTy &RevGroupMap);
- void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
- RelMapTy &RelMap);
+ void createRelocationSection(MCAssembler &Asm, const MCSectionData &SD);
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);
+ std::vector<const MCSectionELF *> &Sections);
// 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,
+ void createIndexedSections(MCAssembler &Asm, MCAsmLayout &Layout,
RevGroupMapTy &RevGroupMap,
- SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap);
+ std::vector<const MCSectionELF *> &Sections,
+ SectionIndexMapTy &SectionIndexMap);
void ExecutePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) override;
- void WriteSectionHeader(MCAssembler &Asm, const GroupMapTy &GroupMap,
- const MCAsmLayout &Layout,
+ void writeSectionHeader(ArrayRef<const MCSectionELF *> Sections,
+ MCAssembler &Asm, const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap,
- const SectionOffsetMapTy &SectionOffsetMap);
-
- void ComputeSectionOrder(MCAssembler &Asm,
- std::vector<const MCSectionELF*> &Sections);
+ const SectionOffsetsTy &SectionOffsets);
void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
uint64_t Address, uint64_t Offset,
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,
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);
ShndxF = new MCDataFragment(SymtabShndxSD);
- unsigned Index = SectionIndexMap.size() + 1;
- SectionIndexMap[SymtabShndxSection] = Index;
+ Sections.push_back(SymtabShndxSection);
for (unsigned I = 0; I < NumWritten; ++I)
write(*ShndxF, uint32_t(0));
FWriter.write(F, Value);
}
-SymbolTableWriter::SymbolTableWriter(MCAssembler &Asm, FragmentWriter &FWriter,
- bool Is64Bit,
- SectionIndexMapTy &SectionIndexMap,
- MCDataFragment *SymtabF)
- : Asm(Asm), FWriter(FWriter), Is64Bit(Is64Bit),
- SectionIndexMap(SectionIndexMap), SymtabF(SymtabF), ShndxF(nullptr),
- NumWritten(0) {}
+SymbolTableWriter::SymbolTableWriter(
+ MCAssembler &Asm, FragmentWriter &FWriter, bool Is64Bit,
+ std::vector<const MCSectionELF *> &Sections, MCDataFragment *SymtabF)
+ : Asm(Asm), FWriter(FWriter), Is64Bit(Is64Bit), Sections(Sections),
+ SymtabF(SymtabF), ShndxF(nullptr), NumWritten(0) {}
void SymbolTableWriter::writeSymbol(uint32_t name, uint8_t info, uint64_t value,
uint64_t size, uint8_t other,
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
// Emit the ELF header.
void ELFObjectWriter::WriteHeader(const MCAssembler &Asm,
- uint64_t SectionDataSize,
unsigned NumberOfSections) {
// ELF Header
// ----------
// emitWord method behaves differently for ELF32 and ELF64, writing
// 4 bytes in the former and 8 in the latter.
- Write8(0x7f); // e_ident[EI_MAG0]
- Write8('E'); // e_ident[EI_MAG1]
- Write8('L'); // e_ident[EI_MAG2]
- Write8('F'); // e_ident[EI_MAG3]
+ WriteBytes(ELF::ElfMagic); // e_ident[EI_MAG0] to e_ident[EI_MAG3]
Write8(is64Bit() ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
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(0); // e_shoff = sec hdr table off in bytes
// e_flags = whatever the target wants
Write32(Asm.getELFHeaderEFlags());
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();
-
- uint64_t Res = 0;
- if (Symbol->isVariable()) {
- const MCExpr *Expr = Symbol->getVariableValue();
- MCValue Value;
- if (!Expr->EvaluateAsRelocatable(Value, &Layout))
- llvm_unreachable("Invalid expression");
+ if (Data.isCommon() && Data.isExternal())
+ return Data.getCommonAlignment();
- assert(!Value.getSymB());
-
- Res = Value.getConstant();
-
- if (const MCSymbolRefExpr *A = Value.getSymA()) {
- Symbol = &A->getSymbol();
- Data = &Layout.getAssembler().getSymbolData(*Symbol);
- } else {
- Symbol = nullptr;
- Data = nullptr;
- }
- }
+ uint64_t Res;
+ if (!Layout.getSymbolOffset(&Data, Res))
+ return 0;
- if ((Data && Data->getFlags() & ELF_Other_ThumbFunc) ||
- OrigData.getFlags() & ELF_Other_ThumbFunc)
+ if (Layout.getAssembler().isThumbFunc(&Data.getSymbol()))
Res |= 1;
- if (!Symbol || !Symbol->isInSection())
- return Res;
-
- Res += Layout.getSymbolOffset(Data);
-
return Res;
}
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");
- const MCSymbolRefExpr *RefB = Value.getSymB();
- if (RefB) {
- Layout.getAssembler().getContext().FatalError(
- SMLoc(), Twine("symbol '") + RefB->getSymbol().getName() +
- "' could not be evaluated in a subtraction expression");
- }
- 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;
(&OrigData.getFragment()->getParent()->getSection() ==
&OrigData.getSymbol().getSection())) &&
"The symbol's section doesn't match the fragment's symbol");
- const MCSymbol *Base = getBaseSymbol(Layout, OrigData.getSymbol());
+ const MCSymbol *Base = Layout.getBaseSymbol(OrigData.getSymbol());
// This has to be in sync with when computeSymbolTable uses SHN_ABS or
// SHN_COMMON.
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
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;
}
MSD.SectionIndex, IsReserved);
}
-void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
- MCAssembler &Asm,
- const MCAsmLayout &Layout,
- SectionIndexMapTy &SectionIndexMap) {
+void ELFObjectWriter::WriteSymbolTable(
+ MCDataFragment *SymtabF, MCAssembler &Asm, const MCAsmLayout &Layout,
+ std::vector<const MCSectionELF *> &Sections) {
// 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.
- SymbolTableWriter Writer(Asm, FWriter, is64Bit(), SectionIndexMap, SymtabF);
+ SymbolTableWriter Writer(Asm, FWriter, is64Bit(), Sections, SymtabF);
// The first entry is the undefined symbol entry.
Writer.writeSymbol(0, 0, 0, 0, 0, 0, false);
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<const MCSectionELF&>(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;
// 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 {
}
// 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;
// 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 (SD->getFlags() & ELF_Other_ThumbFunc)
+ if (Asm.isThumbFunc(&Sym))
return true;
- if (TargetObjectWriter->needsRelocateWithSymbol(Type))
+ 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<MCSymbolRefExpr>(Expr);
+ if (!Inner)
+ return nullptr;
+
+ if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
+ return &Inner->getSymbol();
+ return nullptr;
+}
+
+// True if the assembler knows nothing about the final value of the symbol.
+// This doesn't cover the comdat issues, since in those cases the assembler
+// can at least know that all symbols in the section will move together.
+static bool isWeak(const MCSymbolData &D) {
+ if (MCELF::GetType(D) == ELF::STT_GNU_IFUNC)
+ return true;
+
+ switch (MCELF::GetBinding(D)) {
+ default:
+ llvm_unreachable("Unknown binding");
+ case ELF::STB_LOCAL:
+ return false;
+ case ELF::STB_GLOBAL:
+ return false;
+ case ELF::STB_WEAK:
+ case ELF::STB_GNU_UNIQUE:
+ return true;
+ }
+}
+
+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();
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;
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);
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<MCSectionELF>(SecA);
+ MCSymbol *SectionSymbol =
+ ELFSec ? Asm.getContext().getOrCreateSectionSymbol(*ELFSec)
+ : nullptr;
+ ELFRelocationEntry Rec(FixupOffset, SectionSymbol, Type, Addend);
Relocations[FixupSection].push_back(Rec);
return;
}
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);
}
return true;
if (Symbol.isVariable()) {
- const MCSymbol *Base = getBaseSymbol(Layout, Symbol);
+ const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
if (Base && Base->isUndefined())
return false;
}
return true;
}
-void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
- SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap) {
- unsigned Index = 1;
- for (MCAssembler::iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
- const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
- if (Section.getType() != ELF::SHT_GROUP)
- continue;
- SectionIndexMap[&Section] = Index++;
- }
+void ELFObjectWriter::maybeAddToGroup(MCAssembler &Asm,
+ ArrayRef<const MCSectionELF *> Sections,
+ const RevGroupMapTy &RevGroupMap,
+ const MCSectionELF &Section,
+ unsigned Index) {
+ const MCSymbol *Sym = Section.getGroup();
+ if (!Sym)
+ return;
+ const MCSectionELF *Group = Sections[RevGroupMap.lookup(Sym) - 1];
+ MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
+ // FIXME: we could use the previous fragment
+ MCDataFragment *F = new MCDataFragment(&Data);
+ write(*F, Index);
+}
- for (MCAssembler::iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
+void ELFObjectWriter::computeIndexMap(
+ MCAssembler &Asm, std::vector<const MCSectionELF *> &Sections,
+ SectionIndexMapTy &SectionIndexMap, const RevGroupMapTy &RevGroupMap) {
+ for (const MCSectionData &SD : Asm) {
const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
- if (Section.getType() == ELF::SHT_GROUP ||
- Section.getType() == ELF::SHT_REL ||
- Section.getType() == ELF::SHT_RELA)
+ static_cast<const MCSectionELF &>(SD.getSection());
+ if (Section.getType() == ELF::SHT_GROUP)
continue;
- SectionIndexMap[&Section] = Index++;
- const MCSectionELF *RelSection = RelMap.lookup(&Section);
- if (RelSection)
- SectionIndexMap[RelSection] = Index++;
+ Sections.push_back(&Section);
+ unsigned Index = Sections.size();
+ SectionIndexMap[&Section] = Index;
+ maybeAddToGroup(Asm, Sections, RevGroupMap, Section, Index);
+ createRelocationSection(Asm, SD);
}
}
-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) {
MCELF::SetBinding(Data, ELF::STB_GLOBAL);
}
- // Index 0 is always the empty string.
- StringMap<uint64_t> 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 (MCSymbolData &SD : Asm.symbols()) {
const MCSymbol &Symbol = SD.getSymbol();
ELFSymbolData MSD;
MSD.SymbolData = &SD;
- const MCSymbol *BaseSymbol = getBaseSymbol(Layout, Symbol);
+ const MCSymbol *BaseSymbol = Layout.getBaseSymbol(Symbol);
// Undefined symbols are global, but this is the first place we
// are able to set it.
MSD.SectionIndex = ELF::SHN_COMMON;
} else if (BaseSymbol->isUndefined()) {
if (isSignature && !Used)
- MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
+ MSD.SectionIndex = RevGroupMap.lookup(&Symbol);
else
MSD.SectionIndex = ELF::SHN_UNDEF;
if (!Used && WeakrefUsed)
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)
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());
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;
+void ELFObjectWriter::createRelocationSection(MCAssembler &Asm,
+ const MCSectionData &SD) {
+ if (Relocations[&SD].empty())
+ return;
- MCContext &Ctx = Asm.getContext();
- const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(SD.getSection());
+ MCContext &Ctx = Asm.getContext();
+ const MCSectionELF &Section =
+ static_cast<const MCSectionELF &>(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;
- StringRef Group = "";
- if (Section.getFlags() & ELF::SHF_GROUP) {
- Flags = ELF::SHF_GROUP;
- Group = Section.getGroup()->getName();
- }
+ unsigned Flags = 0;
+ if (Section.getFlags() & ELF::SHF_GROUP)
+ Flags = ELF::SHF_GROUP;
- const MCSectionELF *RelaSection =
- Ctx.getELFSection(RelaSectionName, hasRelocationAddend() ?
- ELF::SHT_RELA : ELF::SHT_REL, Flags,
- SectionKind::getReadOnly(),
- EntrySize, Group);
- RelMap[&Section] = RelaSection;
- Asm.getOrCreateSectionData(*RelaSection);
- }
+ const MCSectionELF *RelaSection = Ctx.createELFRelSection(
+ RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL,
+ Flags, EntrySize, Section.getGroup(), &Section);
+ Asm.getOrCreateSectionData(*RelaSection);
}
static SmallVector<char, 128>
static bool
prependCompressionHeader(uint64_t Size,
SmallVectorImpl<char> &CompressedContents) {
- static const StringRef Magic = "ZLIB";
+ const StringRef Magic = "ZLIB";
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());
}
}
-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;
- const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(SD.getSection());
+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<const MCSectionELF &>(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);
}
}
WriteWord(EntrySize); // sh_entsize
}
-// ELF doesn't require relocations to be in any order. We sort by the r_offset,
-// just to match gnu as for easier comparison. The use type is an arbitrary way
-// of making the sort deterministic.
-static int cmpRel(const ELFRelocationEntry *AP, const ELFRelocationEntry *BP) {
- const ELFRelocationEntry &A = *AP;
- const ELFRelocationEntry &B = *BP;
- if (A.Offset != B.Offset)
- return B.Offset - A.Offset;
- if (B.Type != A.Type)
- return A.Type - B.Type;
- llvm_unreachable("ELFRelocs might be unstable!");
-}
-
-static void sortRelocs(const MCAssembler &Asm,
- std::vector<ELFRelocationEntry> &Relocs) {
- array_pod_sort(Relocs.begin(), Relocs.end(), cmpRel);
-}
-
void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
MCDataFragment *F,
const MCSectionData *SD) {
std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
- sortRelocs(Asm, Relocs);
+ // Sort the relocation entries. Most targets just sort by Offset, but some
+ // (e.g., MIPS) have additional constraints.
+ TargetObjectWriter->sortRelocs(Asm, Relocs);
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);
}
}
-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,
+ std::vector<const MCSectionELF *> &Sections) {
MCContext &Ctx = Asm.getContext();
MCDataFragment *F;
// 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 = Sections.size() + 1;
+ Sections.push_back(ShstrtabSection);
const MCSectionELF *SymtabSection =
Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
- SectionKind::getReadOnly(),
EntrySize, "");
MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
SymtabSD.setAlignment(is64Bit() ? 8 : 4);
+ SymbolTableIndex = Sections.size() + 1;
+ Sections.push_back(SymtabSection);
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 = Sections.size() + 1;
+ Sections.push_back(StrtabSection);
// Symbol table
F = new MCDataFragment(&SymtabSD);
- WriteSymbolTable(F, Asm, Layout, SectionIndexMap);
+ WriteSymbolTable(F, Asm, Layout, Sections);
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<const MCSectionELF*> 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<const MCSectionELF&>(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, RevGroupMapTy &RevGroupMap,
+ std::vector<const MCSectionELF *> &Sections,
+ 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();
- it != ie; ++it) {
+ for (const MCSectionData &SD : Asm) {
const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(it->getSection());
+ static_cast<const MCSectionELF &>(SD.getSection());
if (!(Section.getFlags() & ELF::SHF_GROUP))
continue;
const MCSymbol *SignatureSymbol = Section.getGroup();
Asm.getOrCreateSymbolData(*SignatureSymbol);
- const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
- if (!Group) {
- Group = Ctx.CreateELFGroupSection();
+ unsigned &GroupIdx = RevGroupMap[SignatureSymbol];
+ if (!GroupIdx) {
+ const MCSectionELF *Group = Ctx.createELFGroupSection(SignatureSymbol);
+ Sections.push_back(Group);
+ GroupIdx = Sections.size();
+
MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
Data.setAlignment(4);
MCDataFragment *F = new MCDataFragment(&Data);
write(*F, uint32_t(ELF::GRP_COMDAT));
}
- GroupMap[Group] = SignatureSymbol;
}
- ComputeIndexMap(Asm, SectionIndexMap, RelMap);
-
- // Add sections to the groups
- for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
- it != ie; ++it) {
- const MCSectionELF &Section =
- static_cast<const MCSectionELF&>(it->getSection());
- if (!(Section.getFlags() & ELF::SHF_GROUP))
- continue;
- const MCSectionELF *Group = RevGroupMap[Section.getGroup()];
- MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
- // FIXME: we could use the previous fragment
- MCDataFragment *F = new MCDataFragment(&Data);
- uint32_t Index = SectionIndexMap.lookup(&Section);
- write(*F, Index);
- }
+ computeIndexMap(Asm, Sections, SectionIndexMap, RevGroupMap);
}
-void ELFObjectWriter::WriteSection(MCAssembler &Asm,
+void ELFObjectWriter::writeSection(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
uint32_t GroupSymbolIndex,
uint64_t Offset, uint64_t Size,
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;
}
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());
}
!SD.getSection().isVirtualSection();
}
-uint64_t ELFObjectWriter::DataSectionSize(const MCSectionData &SD) {
- uint64_t Ret = 0;
- for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
- ++i) {
- const MCFragment &F = *i;
- assert(F.getKind() == MCFragment::FT_Data);
- Ret += cast<MCDataFragment>(F).getContents().size();
- }
- return Ret;
-}
-
-uint64_t ELFObjectWriter::GetSectionFileSize(const MCAsmLayout &Layout,
- const MCSectionData &SD) {
- if (IsELFMetaDataSection(SD))
- return DataSectionSize(SD);
- return Layout.getSectionFileSize(&SD);
-}
-
-uint64_t ELFObjectWriter::GetSectionAddressSize(const MCAsmLayout &Layout,
- const MCSectionData &SD) {
- if (IsELFMetaDataSection(SD))
- return DataSectionSize(SD);
- return Layout.getSectionAddressSize(&SD);
-}
-
-void ELFObjectWriter::WriteDataSectionData(MCAssembler &Asm,
+void ELFObjectWriter::writeDataSectionData(MCAssembler &Asm,
const MCAsmLayout &Layout,
- const MCSectionELF &Section) {
- const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
-
- uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment());
- WriteZeros(Padding);
-
+ const MCSectionData &SD) {
if (IsELFMetaDataSection(SD)) {
for (MCSectionData::const_iterator i = SD.begin(), e = SD.end(); i != e;
++i) {
}
}
-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<const MCSectionELF*> Sections;
- Sections.resize(NumSections - 1);
-
- for (SectionIndexMapTy::const_iterator i=
- SectionIndexMap.begin(), e = SectionIndexMap.end(); i != e; ++i) {
- const std::pair<const MCSectionELF*, uint32_t> &p = *i;
- Sections[p.second - 1] = p.first;
- }
+void ELFObjectWriter::writeSectionHeader(
+ ArrayRef<const MCSectionELF *> Sections, MCAssembler &Asm,
+ const MCAsmLayout &Layout, const SectionIndexMapTy &SectionIndexMap,
+ const SectionOffsetsTy &SectionOffsets) {
+ const unsigned NumSections = Asm.size();
// Null section first.
uint64_t FirstSectionSize =
- NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
+ (NumSections + 1) >= ELF::SHN_LORESERVE ? NumSections + 1 : 0;
uint32_t FirstSectionLink =
ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
- for (unsigned i = 0; i < NumSections - 1; ++i) {
+ for (unsigned i = 0; i < NumSections; ++i) {
const MCSectionELF &Section = *Sections[i];
const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
uint32_t GroupSymbolIndex;
if (Section.getType() != ELF::SHT_GROUP)
GroupSymbolIndex = 0;
else
- GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm,
- GroupMap.lookup(&Section));
+ GroupSymbolIndex = getSymbolIndexInSymbolTable(Asm, Section.getGroup());
- uint64_t Size = GetSectionAddressSize(Layout, SD);
+ const std::pair<uint64_t, uint64_t> &Offsets = SectionOffsets[i];
+ uint64_t Size = Section.getType() == ELF::SHT_NOBITS
+ ? Layout.getSectionAddressSize(&SD)
+ : Offsets.second - Offsets.first;
- WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
- SectionOffsetMap.lookup(&Section), Size,
+ writeSection(Asm, SectionIndexMap, GroupSymbolIndex, Offsets.first, Size,
SD.getAlignment(), Section);
}
}
-void ELFObjectWriter::ComputeSectionOrder(MCAssembler &Asm,
- std::vector<const MCSectionELF*> &Sections) {
- for (MCAssembler::iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
- const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
- if (Section.getType() == ELF::SHT_GROUP)
- Sections.push_back(&Section);
- }
-
- for (MCAssembler::iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
- const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
- if (Section.getType() != ELF::SHT_GROUP &&
- Section.getType() != ELF::SHT_REL &&
- Section.getType() != ELF::SHT_RELA)
- Sections.push_back(&Section);
- }
-
- for (MCAssembler::iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it) {
- const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
- if (Section.getType() == ELF::SHT_REL ||
- Section.getType() == ELF::SHT_RELA)
- Sections.push_back(&Section);
- }
-}
-
void ELFObjectWriter::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
- GroupMapTy GroupMap;
RevGroupMapTy RevGroupMap;
SectionIndexMapTy SectionIndexMap;
- unsigned NumUserSections = Asm.size();
-
CompressDebugSections(Asm, const_cast<MCAsmLayout &>(Layout));
-
- DenseMap<const MCSectionELF*, const MCSectionELF*> RelMap;
- CreateRelocationSections(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
-
- const unsigned NumUserAndRelocSections = Asm.size();
- CreateIndexedSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
- RevGroupMap, SectionIndexMap, RelMap);
- const unsigned AllSections = Asm.size();
- const unsigned NumIndexedSections = AllSections - NumUserAndRelocSections;
-
- unsigned NumRegularSections = NumUserSections + NumIndexedSections;
+ std::vector<const MCSectionELF *> Sections;
+ createIndexedSections(Asm, const_cast<MCAsmLayout &>(Layout), RevGroupMap,
+ Sections, SectionIndexMap);
// Compute symbol table information.
- computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap,
- NumRegularSections);
-
- WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
+ computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap);
- CreateMetadataSections(const_cast<MCAssembler&>(Asm),
- const_cast<MCAsmLayout&>(Layout),
- SectionIndexMap,
- RelMap);
+ WriteRelocations(Asm, const_cast<MCAsmLayout &>(Layout));
- uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
- uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
- sizeof(ELF::Elf32_Ehdr);
- uint64_t FileOff = HeaderSize;
-
- std::vector<const MCSectionELF*> Sections;
- ComputeSectionOrder(Asm, Sections);
- unsigned NumSections = Sections.size();
- SectionOffsetMapTy SectionOffsetMap;
- for (unsigned i = 0; i < NumRegularSections + 1; ++i) {
- const MCSectionELF &Section = *Sections[i];
- const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
+ CreateMetadataSections(const_cast<MCAssembler &>(Asm),
+ const_cast<MCAsmLayout &>(Layout), Sections);
- FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
+ unsigned NumSections = Asm.size();
+ SectionOffsetsTy SectionOffsets;
- // 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);
- }
-
- 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);
+ // Write out the ELF header ...
+ WriteHeader(Asm, NumSections + 1);
- FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
+ // ... then the sections ...
+ for (const MCSectionELF *Section : Sections) {
+ const MCSectionData &SD = Asm.getOrCreateSectionData(*Section);
+ uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment());
+ WriteZeros(Padding);
// 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);
+ uint64_t SecStart = OS.tell();
+ writeDataSectionData(Asm, Layout, SD);
+ uint64_t SecEnd = OS.tell();
+ SectionOffsets.push_back(std::make_pair(SecStart, SecEnd));
}
- // 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)
- WriteDataSectionData(Asm, Layout, *Sections[i]);
-
+ uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
uint64_t Padding = OffsetToAlignment(OS.tell(), NaturalAlignment);
WriteZeros(Padding);
+ const unsigned SectionHeaderOffset = OS.tell();
+
// ... then the section header table ...
- WriteSectionHeader(Asm, GroupMap, Layout, SectionIndexMap,
- SectionOffsetMap);
+ writeSectionHeader(Sections, Asm, Layout, SectionIndexMap, SectionOffsets);
+
+ if (is64Bit()) {
+ uint64_t Val = SectionHeaderOffset;
+ if (sys::IsLittleEndianHost != IsLittleEndian)
+ sys::swapByteOrder(Val);
+ OS.pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
+ offsetof(ELF::Elf64_Ehdr, e_shoff));
+ } else {
+ uint32_t Val = SectionHeaderOffset;
+ if (sys::IsLittleEndianHost != IsLittleEndian)
+ sys::swapByteOrder(Val);
+ OS.pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
+ offsetof(ELF::Elf32_Ehdr, e_shoff));
+ }
+}
- // ... and then the remaining sections ...
- for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)
- WriteDataSectionData(Asm, Layout, *Sections[i]);
+bool ELFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
+ const MCAssembler &Asm, const MCSymbolData &DataA, const MCFragment &FB,
+ bool InSet, bool IsPCRel) const {
+ if (IsPCRel) {
+ assert(!InSet);
+ if (::isWeak(DataA))
+ return false;
+ }
+ return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(Asm, DataA, FB,
+ InSet, IsPCRel);
}
-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::isWeak(const MCSymbolData &SD) const {
+ if (::isWeak(SD))
+ return true;
+
+ // It is invalid to replace a reference to a global in a comdat
+ // with a reference to a local since out of comdat references
+ // to a local are forbidden.
+ // We could try to return false for more cases, like the reference
+ // being in the same comdat or Sym being an alias to another global,
+ // but it is not clear if it is worth the effort.
+ if (MCELF::GetBinding(SD) != ELF::STB_GLOBAL)
return false;
- return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
- Asm, DataA, FB,InSet, IsPCRel);
+
+ const MCSymbol &Sym = SD.getSymbol();
+ if (!Sym.isInSection())
+ return false;
+
+ const auto &Sec = cast<MCSectionELF>(Sym.getSection());
+ return Sec.getGroup();
}
MCObjectWriter *llvm::createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
- raw_ostream &OS,
+ raw_pwrite_stream &OS,
bool IsLittleEndian) {
return new ELFObjectWriter(MOTW, OS, IsLittleEndian);
}
projects / oota-llvm.git / blobdiff