#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;
uint8_t other, uint32_t shndx, bool Reserved);
};
-struct ELFRelocationEntry {
- uint64_t Offset; // Where is the relocation.
- 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), Symbol(Symbol), Type(Type), Addend(Addend) {}
-};
-
class ELFObjectWriter : public MCObjectWriter {
FragmentWriter FWriter;
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);
+ void writeDataSectionData(MCAssembler &Asm, const MCAsmLayout &Layout,
+ const MCSectionData &SD);
- /*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;
}
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,
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;
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;
/// \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,
- const RevGroupMapTy &RevGroupMap,
- unsigned NumRegularSections);
+ const RevGroupMapTy &RevGroupMap);
- void ComputeIndexMap(MCAssembler &Asm,
- SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap);
+ void computeIndexMap(MCAssembler &Asm, SectionIndexMapTy &SectionIndexMap);
- void CreateRelocationSections(MCAssembler &Asm, MCAsmLayout &Layout,
- RelMapTy &RelMap);
+ MCSectionData *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);
+ 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(ArrayRef<const MCSectionELF *> Sections,
+ MCAssembler &Asm, const GroupMapTy &GroupMap,
const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap,
const SectionOffsetMapTy &SectionOffsetMap);
- void ComputeSectionOrder(MCAssembler &Asm,
- std::vector<const MCSectionELF*> &Sections);
-
void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
uint64_t Address, uint64_t Offset,
uint64_t Size, uint32_t Link, uint32_t Info,
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);
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());
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;
}
return nullptr;
}
-void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
+// 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;
(SymA && !SymA->isUndefined()) ? &SymA->getSection() : nullptr;
auto *ELFSec = cast_or_null<MCSectionELF>(SecA);
MCSymbol *SectionSymbol =
- ELFSec ? Asm.getContext().GetOrCreateSymbol(ELFSec->getSectionName())
+ ELFSec ? Asm.getContext().getOrCreateSectionSymbol(*ELFSec)
: nullptr;
ELFRelocationEntry Rec(FixupOffset, SectionSymbol, Type, Addend);
Relocations[FixupSection].push_back(Rec);
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) {
SectionIndexMap[&Section] = Index++;
}
+ std::vector<const MCSectionELF *> RelSections;
+
for (MCAssembler::iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
+ const MCSectionData &SD = *it;
const MCSectionELF &Section =
- static_cast<const MCSectionELF &>(it->getSection());
+ static_cast<const MCSectionELF &>(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)
- SectionIndexMap[RelSection] = Index++;
+ if (MCSectionData *RelSD = createRelocationSection(Asm, SD)) {
+ const MCSectionELF *RelSection =
+ static_cast<const MCSectionELF *>(&RelSD->getSection());
+ RelSections.push_back(RelSection);
+ }
}
+
+ // Put relocation sections close together. The linker reads them
+ // first, so this improves cache locality.
+ for (const MCSectionELF * Sec: RelSections)
+ SectionIndexMap[Sec] = Index++;
}
-void
-ELFObjectWriter::computeSymbolTable(MCAssembler &Asm, const MCAsmLayout &Layout,
- const SectionIndexMapTy &SectionIndexMap,
- const 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) {
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;
+ }
}
// Sections have their own string table
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<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);
+ return &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)
}
}
-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];
}
}
-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;
// 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);
ShStrTabBuilder.data().end());
}
-void ELFObjectWriter::CreateIndexedSections(MCAssembler &Asm,
- MCAsmLayout &Layout,
- GroupMapTy &GroupMap,
- RevGroupMapTy &RevGroupMap,
- SectionIndexMapTy &SectionIndexMap,
- const RelMapTy &RelMap) {
+void ELFObjectWriter::createIndexedSections(
+ MCAssembler &Asm, MCAsmLayout &Layout, GroupMapTy &GroupMap,
+ RevGroupMapTy &RevGroupMap, SectionIndexMapTy &SectionIndexMap) {
MCContext &Ctx = Asm.getContext();
// Build the groups
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();
}
}
-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 = ShStrTabBuilder.getOffset(Section.getSectionName());
- sh_info = 0;
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:
- case ELF::SHT_MIPS_ABIFLAGS:
- // Nothing to do.
- break;
-
case ELF::SHT_GROUP:
sh_link = SymbolTableIndex;
sh_info = GroupSymbolIndex;
break;
-
- default:
- llvm_unreachable("FIXME: sh_type value not supported!");
}
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(ShStrTabBuilder.getOffset(Section.getSectionName()),
Section.getType(),
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 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 GroupMapTy &GroupMap, const MCAsmLayout &Layout,
+ const SectionIndexMapTy &SectionIndexMap,
+ const SectionOffsetMapTy &SectionOffsetMap) {
+ 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;
uint64_t Size = GetSectionAddressSize(Layout, SD);
- WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
- SectionOffsetMap.lookup(&Section), 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);
+ writeSection(Asm, SectionIndexMap, GroupSymbolIndex,
+ SectionOffsetMap.lookup(&Section), Size, SD.getAlignment(),
+ Section);
}
}
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;
+ createIndexedSections(Asm, const_cast<MCAsmLayout &>(Layout), GroupMap,
+ RevGroupMap, SectionIndexMap);
// Compute symbol table information.
- computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap,
- NumRegularSections);
+ computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap);
- WriteRelocations(Asm, const_cast<MCAsmLayout&>(Layout), RelMap);
+ WriteRelocations(Asm, const_cast<MCAsmLayout &>(Layout));
CreateMetadataSections(const_cast<MCAssembler&>(Asm),
const_cast<MCAsmLayout&>(Layout),
- SectionIndexMap,
- RelMap);
-
- uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
- uint64_t HeaderSize = is64Bit() ? sizeof(ELF::Elf64_Ehdr) :
- sizeof(ELF::Elf32_Ehdr);
- uint64_t FileOff = HeaderSize;
+ SectionIndexMap);
+ unsigned NumSections = Asm.size();
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);
+ Sections.resize(NumSections);
- FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
+ for (auto &Pair : SectionIndexMap)
+ Sections[Pair.second - 1] = Pair.first;
- // 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;
+ SectionOffsetMapTy SectionOffsetMap;
- uint64_t SectionHeaderEntrySize = is64Bit() ?
- sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr);
- FileOff += (NumSections + 1) * SectionHeaderEntrySize;
+ // Write out the ELF header ...
+ WriteHeader(Asm, NumSections + 1);
- for (unsigned i = NumRegularSections + 1; i < NumSections; ++i) {
+ // ... then the sections ...
+ for (unsigned i = 0; i < NumSections; ++i) {
const MCSectionELF &Section = *Sections[i];
const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
-
- FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
+ uint64_t Padding = OffsetToAlignment(OS.tell(), SD.getAlignment());
+ WriteZeros(Padding);
// Remember the offset into the file for this section.
- SectionOffsetMap[&Section] = FileOff;
+ SectionOffsetMap[&Section] = OS.tell();
- // Get the size of the section in the output file (including padding).
- FileOff += GetSectionFileSize(Layout, SD);
+ writeDataSectionData(Asm, Layout, SD);
}
- // 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,
+ writeSectionHeader(Sections, Asm, GroupMap, Layout, SectionIndexMap,
SectionOffsetMap);
- // ... and then the remaining sections ...
- for (unsigned i = NumRegularSections + 1; i < NumSections; ++i)
- WriteDataSectionData(Asm, Layout, *Sections[i]);
+ 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));
+ }
+}
+
+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;
+
+ const MCSymbol &Sym = SD.getSymbol();
+ if (!Sym.isInSection())
return false;
- return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
- Asm, DataA, FB,InSet, IsPCRel);
+
+ 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