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llvm-6502/lib/MC/ELFObjectWriter.cpp
Rafael Espindola 94ed5fca3f Change MCExpr::EvaluateAsRelocatableImpl of variables to return the original 
variable if recursing fails to simplify it.

Factor AliasedSymbol to be a method of MCSymbol.

Update MCAssembler::EvaluateFixup to match the change in
EvaluateAsRelocatableImpl.

Remove the WeakRefExpr hack, as the object writer now sees the weakref with
no extra effort needed.

Nothing else is using MCTargetExpr, but keep it for now.

Now that the ELF writer sees relocations with aliases, handle

    .weak    foo2
foo2:
    .weak    bar2
    .set    bar2,foo2
    .quad    bar2

the same way gas does and produce a relocation with bar2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119152 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-15 16:33:49 +00:00

1583 lines
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//===- lib/MC/ELFObjectWriter.cpp - ELF File Writer -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements ELF object file writer information.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCELFSymbolFlags.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ELF.h"
#include "llvm/Target/TargetAsmBackend.h"
#include "../Target/X86/X86FixupKinds.h"
#include <vector>
using namespace llvm;
static unsigned GetType(const MCSymbolData &SD) {
uint32_t Type = (SD.getFlags() & (0xf << ELF_STT_Shift)) >> ELF_STT_Shift;
assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
Type == ELF::STT_FILE || Type == ELF::STT_COMMON ||
Type == ELF::STT_TLS);
return Type;
}
static unsigned GetBinding(const MCSymbolData &SD) {
uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
Binding == ELF::STB_WEAK);
return Binding;
}
static void SetBinding(MCSymbolData &SD, unsigned Binding) {
assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
Binding == ELF::STB_WEAK);
uint32_t OtherFlags = SD.getFlags() & ~(0xf << ELF_STB_Shift);
SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift));
}
static unsigned GetVisibility(MCSymbolData &SD) {
unsigned Visibility =
(SD.getFlags() & (0xf << ELF_STV_Shift)) >> ELF_STV_Shift;
assert(Visibility == ELF::STV_DEFAULT || Visibility == ELF::STV_INTERNAL ||
Visibility == ELF::STV_HIDDEN || Visibility == ELF::STV_PROTECTED);
return Visibility;
}
static bool isFixupKindX86PCRel(unsigned Kind) {
switch (Kind) {
default:
return false;
case X86::reloc_pcrel_1byte:
case X86::reloc_pcrel_4byte:
case X86::reloc_riprel_4byte:
case X86::reloc_riprel_4byte_movq_load:
return true;
}
}
static bool RelocNeedsGOT(MCSymbolRefExpr::VariantKind Variant) {
switch (Variant) {
default:
return false;
case MCSymbolRefExpr::VK_GOT:
case MCSymbolRefExpr::VK_PLT:
case MCSymbolRefExpr::VK_GOTPCREL:
case MCSymbolRefExpr::VK_TPOFF:
case MCSymbolRefExpr::VK_TLSGD:
case MCSymbolRefExpr::VK_GOTTPOFF:
case MCSymbolRefExpr::VK_INDNTPOFF:
case MCSymbolRefExpr::VK_NTPOFF:
case MCSymbolRefExpr::VK_GOTNTPOFF:
case MCSymbolRefExpr::VK_TLSLDM:
case MCSymbolRefExpr::VK_DTPOFF:
case MCSymbolRefExpr::VK_TLSLD:
return true;
}
}
namespace {
class ELFObjectWriter : public MCObjectWriter {
protected:
/*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.
struct ELFSymbolData {
MCSymbolData *SymbolData;
uint64_t StringIndex;
uint32_t SectionIndex;
// Support lexicographic sorting.
bool operator<(const ELFSymbolData &RHS) const {
if (GetType(*SymbolData) == ELF::STT_FILE)
return true;
if (GetType(*RHS.SymbolData) == ELF::STT_FILE)
return false;
return SymbolData->getSymbol().getName() <
RHS.SymbolData->getSymbol().getName();
}
};
/// @name Relocation Data
/// @{
struct ELFRelocationEntry {
// Make these big enough for both 32-bit and 64-bit
uint64_t r_offset;
int Index;
unsigned Type;
const MCSymbol *Symbol;
uint64_t r_addend;
// Support lexicographic sorting.
bool operator<(const ELFRelocationEntry &RE) const {
return RE.r_offset < r_offset;
}
};
SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
SmallPtrSet<const MCSymbol *, 16> WeakrefUsedInReloc;
DenseMap<const MCSymbol *, const MCSymbol *> Renames;
llvm::DenseMap<const MCSectionData*,
std::vector<ELFRelocationEntry> > Relocations;
DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
/// @}
/// @name Symbol Table Data
/// @{
SmallString<256> StringTable;
std::vector<ELFSymbolData> LocalSymbolData;
std::vector<ELFSymbolData> ExternalSymbolData;
std::vector<ELFSymbolData> UndefinedSymbolData;
/// @}
bool NeedsGOT;
bool NeedsSymtabShndx;
unsigned Is64Bit : 1;
bool HasRelocationAddend;
Triple::OSType OSType;
uint16_t EMachine;
// This holds the symbol table index of the last local symbol.
unsigned LastLocalSymbolIndex;
// This holds the .strtab section index.
unsigned StringTableIndex;
// This holds the .symtab section index.
unsigned SymbolTableIndex;
unsigned ShstrtabIndex;
const MCSymbol *SymbolToReloc(const MCAssembler &Asm,
const MCValue &Target,
const MCFragment &F) const;
public:
ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
uint16_t _EMachine, bool _HasRelAddend,
Triple::OSType _OSType)
: MCObjectWriter(_OS, IsLittleEndian),
NeedsGOT(false), NeedsSymtabShndx(false),
Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend),
OSType(_OSType), EMachine(_EMachine) {
}
virtual ~ELFObjectWriter();
void WriteWord(uint64_t W) {
if (Is64Bit)
Write64(W);
else
Write32(W);
}
void StringLE16(char *buf, uint16_t Value) {
buf[0] = char(Value >> 0);
buf[1] = char(Value >> 8);
}
void StringLE32(char *buf, uint32_t Value) {
StringLE16(buf, uint16_t(Value >> 0));
StringLE16(buf + 2, uint16_t(Value >> 16));
}
void StringLE64(char *buf, uint64_t Value) {
StringLE32(buf, uint32_t(Value >> 0));
StringLE32(buf + 4, uint32_t(Value >> 32));
}
void StringBE16(char *buf ,uint16_t Value) {
buf[0] = char(Value >> 8);
buf[1] = char(Value >> 0);
}
void StringBE32(char *buf, uint32_t Value) {
StringBE16(buf, uint16_t(Value >> 16));
StringBE16(buf + 2, uint16_t(Value >> 0));
}
void StringBE64(char *buf, uint64_t Value) {
StringBE32(buf, uint32_t(Value >> 32));
StringBE32(buf + 4, uint32_t(Value >> 0));
}
void String8(MCDataFragment &F, uint8_t Value) {
char buf[1];
buf[0] = Value;
F.getContents() += StringRef(buf, 1);
}
void String16(MCDataFragment &F, uint16_t Value) {
char buf[2];
if (isLittleEndian())
StringLE16(buf, Value);
else
StringBE16(buf, Value);
F.getContents() += StringRef(buf, 2);
}
void String32(MCDataFragment &F, uint32_t Value) {
char buf[4];
if (isLittleEndian())
StringLE32(buf, Value);
else
StringBE32(buf, Value);
F.getContents() += StringRef(buf, 4);
}
void String64(MCDataFragment &F, uint64_t Value) {
char buf[8];
if (isLittleEndian())
StringLE64(buf, Value);
else
StringBE64(buf, Value);
F.getContents() += StringRef(buf, 8);
}
virtual void WriteHeader(uint64_t SectionDataSize, unsigned NumberOfSections);
virtual void WriteSymbolEntry(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
uint64_t name, uint8_t info,
uint64_t value, uint64_t size,
uint8_t other, uint32_t shndx,
bool Reserved);
virtual void WriteSymbol(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
ELFSymbolData &MSD,
const MCAsmLayout &Layout);
typedef DenseMap<const MCSectionELF*, uint32_t> SectionIndexMapTy;
virtual void WriteSymbolTable(MCDataFragment *SymtabF, MCDataFragment *ShndxF,
const MCAssembler &Asm,
const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap);
virtual void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment, const MCFixup &Fixup,
MCValue Target, uint64_t &FixedValue) {
assert(0 && "RecordRelocation is not specific enough");
};
virtual 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;
/// ComputeSymbolTable - Compute the symbol table data
///
/// \param StringTable [out] - The string table data.
/// \param StringIndexMap [out] - Map from symbol names to offsets in the
/// string table.
virtual void ComputeSymbolTable(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
RevGroupMapTy RevGroupMap);
virtual void ComputeIndexMap(MCAssembler &Asm,
SectionIndexMapTy &SectionIndexMap);
virtual void WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
const MCSectionData &SD);
virtual void WriteRelocations(MCAssembler &Asm, MCAsmLayout &Layout) {
for (MCAssembler::const_iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
WriteRelocation(Asm, Layout, *it);
}
}
virtual void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap);
virtual void CreateGroupSections(MCAssembler &Asm, MCAsmLayout &Layout,
GroupMapTy &GroupMap, RevGroupMapTy &RevGroupMap);
virtual void ExecutePostLayoutBinding(MCAssembler &Asm);
virtual 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,
uint64_t Alignment, uint64_t EntrySize);
virtual void WriteRelocationsFragment(const MCAssembler &Asm, MCDataFragment *F,
const MCSectionData *SD);
virtual bool IsFixupFullyResolved(const MCAssembler &Asm,
const MCValue Target,
bool IsPCRel,
const MCFragment *DF) const;
virtual void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
virtual void WriteSection(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
uint32_t GroupSymbolIndex,
uint64_t Offset, uint64_t Size, uint64_t Alignment,
const MCSectionELF &Section);
};
//===- X86ELFObjectWriter -------------------------------------------===//
class X86ELFObjectWriter : public ELFObjectWriter {
public:
X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
uint16_t _EMachine, bool _HasRelAddend,
Triple::OSType _OSType);
virtual ~X86ELFObjectWriter();
virtual void RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue);
};
//===- ARMELFObjectWriter -------------------------------------------===//
class ARMELFObjectWriter : public ELFObjectWriter {
public:
ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool IsLittleEndian,
uint16_t _EMachine, bool _HasRelAddend,
Triple::OSType _OSType);
virtual ~ARMELFObjectWriter();
virtual void RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue);
};
}
ELFObjectWriter::~ELFObjectWriter()
{}
// Emit the ELF header.
void ELFObjectWriter::WriteHeader(uint64_t SectionDataSize,
unsigned NumberOfSections) {
// ELF Header
// ----------
//
// Note
// ----
// 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]
Write8(Is64Bit ? ELF::ELFCLASS64 : ELF::ELFCLASS32); // e_ident[EI_CLASS]
// e_ident[EI_DATA]
Write8(isLittleEndian() ? ELF::ELFDATA2LSB : ELF::ELFDATA2MSB);
Write8(ELF::EV_CURRENT); // e_ident[EI_VERSION]
// e_ident[EI_OSABI]
switch (OSType) {
case Triple::FreeBSD: Write8(ELF::ELFOSABI_FREEBSD); break;
case Triple::Linux: Write8(ELF::ELFOSABI_LINUX); break;
default: Write8(ELF::ELFOSABI_NONE); break;
}
Write8(0); // e_ident[EI_ABIVERSION]
WriteZeros(ELF::EI_NIDENT - ELF::EI_PAD);
Write16(ELF::ET_REL); // e_type
Write16(EMachine); // e_machine = target
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
// FIXME: Make this configurable.
Write32(0); // e_flags = whatever the target wants
// e_ehsize = ELF header size
Write16(Is64Bit ? sizeof(ELF::Elf64_Ehdr) : sizeof(ELF::Elf32_Ehdr));
Write16(0); // e_phentsize = prog header entry size
Write16(0); // e_phnum = # prog header entries = 0
// e_shentsize = Section header entry size
Write16(Is64Bit ? sizeof(ELF::Elf64_Shdr) : sizeof(ELF::Elf32_Shdr));
// e_shnum = # of section header ents
if (NumberOfSections >= ELF::SHN_LORESERVE)
Write16(0);
else
Write16(NumberOfSections);
// e_shstrndx = Section # of '.shstrtab'
if (NumberOfSections >= ELF::SHN_LORESERVE)
Write16(ELF::SHN_XINDEX);
else
Write16(ShstrtabIndex);
}
void ELFObjectWriter::WriteSymbolEntry(MCDataFragment *SymtabF,
MCDataFragment *ShndxF,
uint64_t name,
uint8_t info, uint64_t value,
uint64_t size, uint8_t other,
uint32_t shndx,
bool Reserved) {
if (ShndxF) {
if (shndx >= ELF::SHN_LORESERVE && !Reserved)
String32(*ShndxF, shndx);
else
String32(*ShndxF, 0);
}
uint16_t Index = (shndx >= ELF::SHN_LORESERVE && !Reserved) ?
uint16_t(ELF::SHN_XINDEX) : shndx;
if (Is64Bit) {
String32(*SymtabF, name); // st_name
String8(*SymtabF, info); // st_info
String8(*SymtabF, other); // st_other
String16(*SymtabF, Index); // st_shndx
String64(*SymtabF, value); // st_value
String64(*SymtabF, size); // st_size
} else {
String32(*SymtabF, name); // st_name
String32(*SymtabF, value); // st_value
String32(*SymtabF, size); // st_size
String8(*SymtabF, info); // st_info
String8(*SymtabF, other); // st_other
String16(*SymtabF, Index); // st_shndx
}
}
static uint64_t SymbolValue(MCSymbolData &Data, const MCAsmLayout &Layout) {
if (Data.isCommon() && Data.isExternal())
return Data.getCommonAlignment();
const MCSymbol &Symbol = Data.getSymbol();
if (!Symbol.isInSection())
return 0;
if (MCFragment *FF = Data.getFragment())
return Layout.getSymbolAddress(&Data) -
Layout.getSectionAddress(FF->getParent());
return 0;
}
void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
// The presence of symbol versions causes undefined symbols and
// versions declared with @@@ to be renamed.
for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
ie = Asm.symbol_end(); it != ie; ++it) {
const MCSymbol &Alias = it->getSymbol();
const MCSymbol &Symbol = Alias.AliasedSymbol();
MCSymbolData &SD = Asm.getSymbolData(Symbol);
// Not an alias.
if (&Symbol == &Alias)
continue;
StringRef AliasName = Alias.getName();
size_t Pos = AliasName.find('@');
if (Pos == StringRef::npos)
continue;
// Aliases defined with .symvar copy the binding from the symbol they alias.
// This is the first place we are able to copy this information.
it->setExternal(SD.isExternal());
SetBinding(*it, GetBinding(SD));
StringRef Rest = AliasName.substr(Pos);
if (!Symbol.isUndefined() && !Rest.startswith("@@@"))
continue;
// FIXME: produce a better error message.
if (Symbol.isUndefined() && Rest.startswith("@@") &&
!Rest.startswith("@@@"))
report_fatal_error("A @@ version cannot be undefined");
Renames.insert(std::make_pair(&Symbol, &Alias));
}
}
void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
MCDataFragment *ShndxF,
ELFSymbolData &MSD,
const MCAsmLayout &Layout) {
MCSymbolData &OrigData = *MSD.SymbolData;
MCSymbolData &Data =
Layout.getAssembler().getSymbolData(OrigData.getSymbol().AliasedSymbol());
bool IsReserved = Data.isCommon() || Data.getSymbol().isAbsolute() ||
Data.getSymbol().isVariable();
uint8_t Binding = GetBinding(OrigData);
uint8_t Visibility = GetVisibility(OrigData);
uint8_t Type = GetType(Data);
uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
uint8_t Other = Visibility;
uint64_t Value = SymbolValue(Data, Layout);
uint64_t Size = 0;
const MCExpr *ESize;
assert(!(Data.isCommon() && !Data.isExternal()));
ESize = Data.getSize();
if (Data.getSize()) {
MCValue Res;
if (ESize->getKind() == MCExpr::Binary) {
const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(ESize);
if (BE->EvaluateAsRelocatable(Res, &Layout)) {
assert(!Res.getSymA() || !Res.getSymA()->getSymbol().isDefined());
assert(!Res.getSymB() || !Res.getSymB()->getSymbol().isDefined());
Size = Res.getConstant();
}
} else if (ESize->getKind() == MCExpr::Constant) {
Size = static_cast<const MCConstantExpr *>(ESize)->getValue();
} else {
assert(0 && "Unsupported size expression");
}
}
// Write out the symbol table entry
WriteSymbolEntry(SymtabF, ShndxF, MSD.StringIndex, Info, Value,
Size, Other, MSD.SectionIndex, IsReserved);
}
void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
MCDataFragment *ShndxF,
const MCAssembler &Asm,
const MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap) {
// The string table must be emitted first because we need the index
// into the string table for all the symbol names.
assert(StringTable.size() && "Missing string table");
// FIXME: Make sure the start of the symbol table is aligned.
// The first entry is the undefined symbol entry.
WriteSymbolEntry(SymtabF, ShndxF, 0, 0, 0, 0, 0, 0, false);
// Write the symbol table entries.
LastLocalSymbolIndex = LocalSymbolData.size() + 1;
for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) {
ELFSymbolData &MSD = LocalSymbolData[i];
WriteSymbol(SymtabF, ShndxF, 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)
continue;
WriteSymbolEntry(SymtabF, ShndxF, 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;
assert(((Data.getFlags() & ELF_STB_Global) ||
(Data.getFlags() & ELF_STB_Weak)) &&
"External symbol requires STB_GLOBAL or STB_WEAK flag");
WriteSymbol(SymtabF, ShndxF, MSD, Layout);
if (GetBinding(Data) == ELF::STB_LOCAL)
LastLocalSymbolIndex++;
}
for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) {
ELFSymbolData &MSD = UndefinedSymbolData[i];
MCSymbolData &Data = *MSD.SymbolData;
WriteSymbol(SymtabF, ShndxF, MSD, Layout);
if (GetBinding(Data) == ELF::STB_LOCAL)
LastLocalSymbolIndex++;
}
}
const MCSymbol *ELFObjectWriter::SymbolToReloc(const MCAssembler &Asm,
const MCValue &Target,
const MCFragment &F) const {
const MCSymbol &Symbol = Target.getSymA()->getSymbol();
const MCSymbol &ASymbol = Symbol.AliasedSymbol();
const MCSymbol *Renamed = Renames.lookup(&Symbol);
const MCSymbolData &SD = Asm.getSymbolData(Symbol);
if (ASymbol.isUndefined()) {
if (Renamed)
return Renamed;
return &ASymbol;
}
if (SD.isExternal()) {
if (Renamed)
return Renamed;
return &Symbol;
}
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(ASymbol.getSection());
if (Section.getKind().isBSS())
return NULL;
MCSymbolRefExpr::VariantKind Kind = Target.getSymA()->getKind();
const MCSectionELF &Sec2 =
static_cast<const MCSectionELF&>(F.getParent()->getSection());
if (&Sec2 != &Section &&
(Kind == MCSymbolRefExpr::VK_PLT ||
Kind == MCSymbolRefExpr::VK_GOTPCREL ||
Kind == MCSymbolRefExpr::VK_GOTOFF)) {
if (Renamed)
return Renamed;
return &Symbol;
}
if (Section.getFlags() & MCSectionELF::SHF_MERGE) {
if (Target.getConstant() == 0)
return NULL;
if (Renamed)
return Renamed;
return &Symbol;
}
return NULL;
}
uint64_t
ELFObjectWriter::getSymbolIndexInSymbolTable(const MCAssembler &Asm,
const MCSymbol *S) {
MCSymbolData &SD = Asm.getSymbolData(*S);
return SD.getIndex();
}
static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
bool Used, bool Renamed) {
if (Data.getFlags() & ELF_Other_Weakref)
return false;
if (Used)
return true;
if (Renamed)
return false;
const MCSymbol &Symbol = Data.getSymbol();
if (Symbol.getName() == "_GLOBAL_OFFSET_TABLE_")
return true;
const MCSymbol &A = Symbol.AliasedSymbol();
if (!A.isVariable() && A.isUndefined() && !Data.isCommon())
return false;
if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
return false;
if (Symbol.isTemporary())
return false;
return true;
}
static bool isLocal(const MCSymbolData &Data, bool isSignature,
bool isUsedInReloc) {
if (Data.isExternal())
return false;
const MCSymbol &Symbol = Data.getSymbol();
const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
if (RefSymbol.isUndefined() && !RefSymbol.isVariable()) {
if (isSignature && !isUsedInReloc)
return true;
return false;
}
return true;
}
void ELFObjectWriter::ComputeIndexMap(MCAssembler &Asm,
SectionIndexMapTy &SectionIndexMap) {
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++;
}
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::ComputeSymbolTable(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
RevGroupMapTy RevGroupMap) {
// FIXME: Is this the correct place to do this?
if (NeedsGOT) {
llvm::StringRef Name = "_GLOBAL_OFFSET_TABLE_";
MCSymbol *Sym = Asm.getContext().GetOrCreateSymbol(Name);
MCSymbolData &Data = Asm.getOrCreateSymbolData(*Sym);
Data.setExternal(true);
SetBinding(Data, ELF::STB_GLOBAL);
}
// Build section lookup table.
int NumRegularSections = Asm.size();
// Index 0 is always the empty string.
StringMap<uint64_t> StringIndexMap;
StringTable += '\x00';
// Add the data for the symbols.
for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
ie = Asm.symbol_end(); it != ie; ++it) {
const MCSymbol &Symbol = it->getSymbol();
bool Used = UsedInReloc.count(&Symbol);
bool WeakrefUsed = WeakrefUsedInReloc.count(&Symbol);
bool isSignature = RevGroupMap.count(&Symbol);
if (!isInSymtab(Asm, *it,
Used || WeakrefUsed || isSignature,
Renames.count(&Symbol)))
continue;
ELFSymbolData MSD;
MSD.SymbolData = it;
const MCSymbol &RefSymbol = Symbol.AliasedSymbol();
// Undefined symbols are global, but this is the first place we
// are able to set it.
bool Local = isLocal(*it, isSignature, Used);
if (!Local && GetBinding(*it) == ELF::STB_LOCAL) {
MCSymbolData &SD = Asm.getSymbolData(RefSymbol);
SetBinding(*it, ELF::STB_GLOBAL);
SetBinding(SD, ELF::STB_GLOBAL);
}
if (RefSymbol.isUndefined() && !Used && WeakrefUsed)
SetBinding(*it, ELF::STB_WEAK);
if (it->isCommon()) {
assert(!Local);
MSD.SectionIndex = ELF::SHN_COMMON;
} else if (Symbol.isAbsolute() || RefSymbol.isVariable()) {
MSD.SectionIndex = ELF::SHN_ABS;
} else if (RefSymbol.isUndefined()) {
if (isSignature && !Used)
MSD.SectionIndex = SectionIndexMap.lookup(RevGroupMap[&Symbol]);
else
MSD.SectionIndex = ELF::SHN_UNDEF;
} else {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(RefSymbol.getSection());
MSD.SectionIndex = SectionIndexMap.lookup(&Section);
if (MSD.SectionIndex >= ELF::SHN_LORESERVE)
NeedsSymtabShndx = true;
assert(MSD.SectionIndex && "Invalid section index!");
}
// The @@@ in symbol version is replaced with @ in undefined symbols and
// @@ in defined ones.
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;
}
uint64_t &Entry = StringIndexMap[Name];
if (!Entry) {
Entry = StringTable.size();
StringTable += Name;
StringTable += '\x00';
}
MSD.StringIndex = Entry;
if (MSD.SectionIndex == ELF::SHN_UNDEF)
UndefinedSymbolData.push_back(MSD);
else if (Local)
LocalSymbolData.push_back(MSD);
else
ExternalSymbolData.push_back(MSD);
}
// Symbols are required to be in lexicographic order.
array_pod_sort(LocalSymbolData.begin(), LocalSymbolData.end());
array_pod_sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
array_pod_sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
// Set the symbol indices. Local symbols must come before all other
// symbols with non-local bindings.
unsigned Index = 1;
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::WriteRelocation(MCAssembler &Asm, MCAsmLayout &Layout,
const MCSectionData &SD) {
if (!Relocations[&SD].empty()) {
MCContext &Ctx = Asm.getContext();
const MCSectionELF *RelaSection;
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(SD.getSection());
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);
RelaSection = Ctx.getELFSection(RelaSectionName, HasRelocationAddend ?
ELF::SHT_RELA : ELF::SHT_REL, 0,
SectionKind::getReadOnly(),
EntrySize, "");
MCSectionData &RelaSD = Asm.getOrCreateSectionData(*RelaSection);
RelaSD.setAlignment(Is64Bit ? 8 : 4);
MCDataFragment *F = new MCDataFragment(&RelaSD);
WriteRelocationsFragment(Asm, F, &SD);
Asm.AddSectionToTheEnd(*this, RelaSD, Layout);
}
}
void ELFObjectWriter::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,
uint64_t Alignment,
uint64_t EntrySize) {
Write32(Name); // sh_name: index into string table
Write32(Type); // sh_type
WriteWord(Flags); // sh_flags
WriteWord(Address); // sh_addr
WriteWord(Offset); // sh_offset
WriteWord(Size); // sh_size
Write32(Link); // sh_link
Write32(Info); // sh_info
WriteWord(Alignment); // sh_addralign
WriteWord(EntrySize); // sh_entsize
}
void ELFObjectWriter::WriteRelocationsFragment(const MCAssembler &Asm,
MCDataFragment *F,
const MCSectionData *SD) {
std::vector<ELFRelocationEntry> &Relocs = Relocations[SD];
// sort by the r_offset just like gnu as does
array_pod_sort(Relocs.begin(), Relocs.end());
for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
ELFRelocationEntry entry = Relocs[e - i - 1];
if (entry.Index < 0)
entry.Index = getSymbolIndexInSymbolTable(Asm, entry.Symbol);
else
entry.Index += LocalSymbolData.size() + 1;
if (Is64Bit) {
String64(*F, entry.r_offset);
struct ELF::Elf64_Rela ERE64;
ERE64.setSymbolAndType(entry.Index, entry.Type);
String64(*F, ERE64.r_info);
if (HasRelocationAddend)
String64(*F, entry.r_addend);
} else {
String32(*F, entry.r_offset);
struct ELF::Elf32_Rela ERE32;
ERE32.setSymbolAndType(entry.Index, entry.Type);
String32(*F, ERE32.r_info);
if (HasRelocationAddend)
String32(*F, entry.r_addend);
}
}
}
void ELFObjectWriter::CreateMetadataSections(MCAssembler &Asm,
MCAsmLayout &Layout,
const SectionIndexMapTy &SectionIndexMap) {
MCContext &Ctx = Asm.getContext();
MCDataFragment *F;
unsigned EntrySize = Is64Bit ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
// 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());
MCSectionData &ShstrtabSD = Asm.getOrCreateSectionData(*ShstrtabSection);
ShstrtabSD.setAlignment(1);
ShstrtabIndex = Asm.size();
const MCSectionELF *SymtabSection =
Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0,
SectionKind::getReadOnly(),
EntrySize, "");
MCSectionData &SymtabSD = Asm.getOrCreateSectionData(*SymtabSection);
SymtabSD.setAlignment(Is64Bit ? 8 : 4);
SymbolTableIndex = Asm.size();
MCSectionData *SymtabShndxSD = NULL;
if (NeedsSymtabShndx) {
const MCSectionELF *SymtabShndxSection =
Ctx.getELFSection(".symtab_shndx", ELF::SHT_SYMTAB_SHNDX, 0,
SectionKind::getReadOnly(), 4, "");
SymtabShndxSD = &Asm.getOrCreateSectionData(*SymtabShndxSection);
SymtabShndxSD->setAlignment(4);
}
const MCSection *StrtabSection;
StrtabSection = Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0,
SectionKind::getReadOnly());
MCSectionData &StrtabSD = Asm.getOrCreateSectionData(*StrtabSection);
StrtabSD.setAlignment(1);
StringTableIndex = Asm.size();
WriteRelocations(Asm, Layout);
// Symbol table
F = new MCDataFragment(&SymtabSD);
MCDataFragment *ShndxF = NULL;
if (NeedsSymtabShndx) {
ShndxF = new MCDataFragment(SymtabShndxSD);
Asm.AddSectionToTheEnd(*this, *SymtabShndxSD, Layout);
}
WriteSymbolTable(F, ShndxF, Asm, Layout, SectionIndexMap);
Asm.AddSectionToTheEnd(*this, SymtabSD, Layout);
F = new MCDataFragment(&StrtabSD);
F->getContents().append(StringTable.begin(), StringTable.end());
Asm.AddSectionToTheEnd(*this, StrtabSD, Layout);
F = new MCDataFragment(&ShstrtabSD);
// 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() += '\x00';
StringMap<uint64_t> SecStringMap;
for (MCAssembler::const_iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(it->getSection());
// FIXME: We could merge suffixes like in .text and .rela.text.
StringRef Name = Section.getSectionName();
if (SecStringMap.count(Name)) {
SectionStringTableIndex[&Section] = SecStringMap[Name];
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;
SecStringMap[Name] = Index;
Index += Name.size() + 1;
F->getContents() += Name;
F->getContents() += '\x00';
}
Asm.AddSectionToTheEnd(*this, ShstrtabSD, Layout);
}
bool ELFObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
const MCValue Target,
bool IsPCRel,
const MCFragment *DF) const {
// If this is a PCrel relocation, find the section this fixup value is
// relative to.
const MCSection *BaseSection = 0;
if (IsPCRel) {
BaseSection = &DF->getParent()->getSection();
assert(BaseSection);
}
const MCSection *SectionA = 0;
const MCSymbol *SymbolA = 0;
if (const MCSymbolRefExpr *A = Target.getSymA()) {
SymbolA = &A->getSymbol().AliasedSymbol();
SectionA = &SymbolA->getSection();
}
const MCSection *SectionB = 0;
if (const MCSymbolRefExpr *B = Target.getSymB()) {
SectionB = &B->getSymbol().AliasedSymbol().getSection();
}
if (!BaseSection)
return SectionA == SectionB;
const MCSymbolData &DataA = Asm.getSymbolData(*SymbolA);
if (DataA.isExternal())
return false;
return !SectionB && BaseSection == SectionA;
}
void ELFObjectWriter::CreateGroupSections(MCAssembler &Asm,
MCAsmLayout &Layout,
GroupMapTy &GroupMap,
RevGroupMapTy &RevGroupMap) {
// Build 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() & MCSectionELF::SHF_GROUP))
continue;
const MCSymbol *SignatureSymbol = Section.getGroup();
Asm.getOrCreateSymbolData(*SignatureSymbol);
const MCSectionELF *&Group = RevGroupMap[SignatureSymbol];
if (!Group) {
Group = Asm.getContext().CreateELFGroupSection();
MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
Data.setAlignment(4);
MCDataFragment *F = new MCDataFragment(&Data);
String32(*F, ELF::GRP_COMDAT);
}
GroupMap[Group] = SignatureSymbol;
}
// Add sections to the groups
unsigned Index = 1;
unsigned NumGroups = RevGroupMap.size();
for (MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end();
it != ie; ++it, ++Index) {
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(it->getSection());
if (!(Section.getFlags() & MCSectionELF::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);
String32(*F, NumGroups + Index);
}
for (RevGroupMapTy::const_iterator i = RevGroupMap.begin(),
e = RevGroupMap.end(); i != e; ++i) {
const MCSectionELF *Group = i->second;
MCSectionData &Data = Asm.getOrCreateSectionData(*Group);
Asm.AddSectionToTheEnd(*this, Data, Layout);
}
}
void ELFObjectWriter::WriteSection(MCAssembler &Asm,
const SectionIndexMapTy &SectionIndexMap,
uint32_t GroupSymbolIndex,
uint64_t Offset, uint64_t Size,
uint64_t Alignment,
const MCSectionELF &Section) {
uint64_t sh_link = 0;
uint64_t sh_info = 0;
switch(Section.getType()) {
case ELF::SHT_DYNAMIC:
sh_link = SectionStringTableIndex[&Section];
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);
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);
InfoSection = Asm.getContext().getELFSection(SectionName,
ELF::SHT_PROGBITS, 0,
SectionKind::getReadOnly());
sh_info = SectionIndexMap.lookup(InfoSection);
break;
}
case ELF::SHT_SYMTAB:
case ELF::SHT_DYNSYM:
sh_link = StringTableIndex;
sh_info = LastLocalSymbolIndex;
break;
case ELF::SHT_SYMTAB_SHNDX:
sh_link = SymbolTableIndex;
break;
case ELF::SHT_PROGBITS:
case ELF::SHT_STRTAB:
case ELF::SHT_NOBITS:
case ELF::SHT_NULL:
case ELF::SHT_ARM_ATTRIBUTES:
// 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;
}
WriteSecHdrEntry(SectionStringTableIndex[&Section], Section.getType(),
Section.getFlags(), 0, Offset, Size, sh_link, sh_info,
Alignment, Section.getEntrySize());
}
void ELFObjectWriter::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
GroupMapTy GroupMap;
RevGroupMapTy RevGroupMap;
CreateGroupSections(Asm, const_cast<MCAsmLayout&>(Layout), GroupMap,
RevGroupMap);
SectionIndexMapTy SectionIndexMap;
ComputeIndexMap(Asm, SectionIndexMap);
// Compute symbol table information.
ComputeSymbolTable(Asm, SectionIndexMap, RevGroupMap);
CreateMetadataSections(const_cast<MCAssembler&>(Asm),
const_cast<MCAsmLayout&>(Layout),
SectionIndexMap);
// Update to include the metadata sections.
ComputeIndexMap(Asm, SectionIndexMap);
// Add 1 for the null section.
unsigned NumSections = Asm.size() + 1;
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;
Sections.resize(NumSections);
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] = p.first;
}
for (unsigned i = 1; i < NumSections; ++i) {
const MCSectionELF &Section = *Sections[i];
const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
FileOff = RoundUpToAlignment(FileOff, SD.getAlignment());
// Get the size of the section in the output file (including padding).
uint64_t Size = Layout.getSectionFileSize(&SD);
FileOff += Size;
}
FileOff = RoundUpToAlignment(FileOff, NaturalAlignment);
// Write out the ELF header ...
WriteHeader(FileOff - HeaderSize, NumSections);
FileOff = HeaderSize;
// ... then all of the sections ...
DenseMap<const MCSection*, uint64_t> SectionOffsetMap;
for (unsigned i = 1; i < NumSections; ++i) {
const MCSectionELF &Section = *Sections[i];
const MCSectionData &SD = Asm.getOrCreateSectionData(Section);
uint64_t Padding = OffsetToAlignment(FileOff, SD.getAlignment());
WriteZeros(Padding);
FileOff += Padding;
// Remember the offset into the file for this section.
SectionOffsetMap[&Section] = FileOff;
FileOff += Layout.getSectionFileSize(&SD);
Asm.WriteSectionData(&SD, Layout, this);
}
uint64_t Padding = OffsetToAlignment(FileOff, NaturalAlignment);
WriteZeros(Padding);
FileOff += Padding;
// ... and then the section header table.
// Should we align the section header table?
//
// Null section first.
uint64_t FirstSectionSize =
NumSections >= ELF::SHN_LORESERVE ? NumSections : 0;
uint32_t FirstSectionLink =
ShstrtabIndex >= ELF::SHN_LORESERVE ? ShstrtabIndex : 0;
WriteSecHdrEntry(0, 0, 0, 0, 0, FirstSectionSize, FirstSectionLink, 0, 0, 0);
for (unsigned i = 1; 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[&Section]);
WriteSection(Asm, SectionIndexMap, GroupSymbolIndex,
SectionOffsetMap[&Section], Layout.getSectionSize(&SD),
SD.getAlignment(), Section);
}
}
MCObjectWriter *llvm::createELFObjectWriter(raw_ostream &OS,
bool Is64Bit,
Triple::OSType OSType,
uint16_t EMachine,
bool IsLittleEndian,
bool HasRelocationAddend) {
switch (EMachine) {
case ELF::EM_386:
case ELF::EM_X86_64:
return new X86ELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
HasRelocationAddend, OSType); break;
case ELF::EM_ARM:
return new ARMELFObjectWriter(OS, Is64Bit, IsLittleEndian, EMachine,
HasRelocationAddend, OSType); break;
default: assert(0 && "Unsupported architecture"); break;
}
}
/// START OF SUBCLASSES for ELFObjectWriter
//===- ARMELFObjectWriter -------------------------------------------===//
ARMELFObjectWriter::ARMELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
bool _IsLittleEndian,
uint16_t _EMachine, bool _HasRelocationAddend,
Triple::OSType _OSType)
: ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
_HasRelocationAddend, _OSType)
{}
ARMELFObjectWriter::~ARMELFObjectWriter()
{}
void ARMELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup,
MCValue Target,
uint64_t &FixedValue) {
assert(0 && "ARMELFObjectWriter::RecordRelocation() unimplemented");
}
//===- X86ELFObjectWriter -------------------------------------------===//
X86ELFObjectWriter::X86ELFObjectWriter(raw_ostream &_OS, bool _Is64Bit,
bool _IsLittleEndian,
uint16_t _EMachine, bool _HasRelocationAddend,
Triple::OSType _OSType)
: ELFObjectWriter(_OS, _Is64Bit, _IsLittleEndian, _EMachine,
_HasRelocationAddend, _OSType)
{}
X86ELFObjectWriter::~X86ELFObjectWriter()
{}
void X86ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup,
MCValue Target,
uint64_t &FixedValue) {
int64_t Addend = 0;
int Index = 0;
int64_t Value = Target.getConstant();
const MCSymbol &Symbol = Target.getSymA()->getSymbol();
const MCSymbol &ASymbol = Symbol.AliasedSymbol();
const MCSymbol *RelocSymbol = SymbolToReloc(Asm, Target, *Fragment);
bool IsPCRel = isFixupKindX86PCRel(Fixup.getKind());
if (!Target.isAbsolute()) {
if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
const MCSymbol &SymbolB = RefB->getSymbol();
MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
IsPCRel = true;
MCSectionData *Sec = Fragment->getParent();
// Offset of the symbol in the section
int64_t a = Layout.getSymbolAddress(&SDB) - Layout.getSectionAddress(Sec);
// Ofeset of the relocation in the section
int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
Value += b - a;
}
if (!RelocSymbol) {
MCSymbolData &SD = Asm.getSymbolData(ASymbol);
MCFragment *F = SD.getFragment();
Index = F->getParent()->getOrdinal();
MCSectionData *FSD = F->getParent();
// Offset of the symbol in the section
Value += Layout.getSymbolAddress(&SD) - Layout.getSectionAddress(FSD);
} else {
if (Asm.getSymbolData(Symbol).getFlags() & ELF_Other_Weakref)
WeakrefUsedInReloc.insert(RelocSymbol);
else
UsedInReloc.insert(RelocSymbol);
Index = -1;
}
Addend = Value;
// Compensate for the addend on i386.
if (Is64Bit)
Value = 0;
}
FixedValue = Value;
// determine the type of the relocation
MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
unsigned Type;
if (Is64Bit) {
if (IsPCRel) {
switch (Modifier) {
default:
llvm_unreachable("Unimplemented");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_X86_64_PC32;
break;
case MCSymbolRefExpr::VK_PLT:
Type = ELF::R_X86_64_PLT32;
break;
case MCSymbolRefExpr::VK_GOTPCREL:
Type = ELF::R_X86_64_GOTPCREL;
break;
case MCSymbolRefExpr::VK_GOTTPOFF:
Type = ELF::R_X86_64_GOTTPOFF;
break;
case MCSymbolRefExpr::VK_TLSGD:
Type = ELF::R_X86_64_TLSGD;
break;
case MCSymbolRefExpr::VK_TLSLD:
Type = ELF::R_X86_64_TLSLD;
break;
}
} else {
switch ((unsigned)Fixup.getKind()) {
default: llvm_unreachable("invalid fixup kind!");
case FK_Data_8: Type = ELF::R_X86_64_64; break;
case X86::reloc_signed_4byte:
case X86::reloc_pcrel_4byte:
assert(isInt<32>(Target.getConstant()));
switch (Modifier) {
default:
llvm_unreachable("Unimplemented");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_X86_64_32S;
break;
case MCSymbolRefExpr::VK_GOT:
Type = ELF::R_X86_64_GOT32;
break;
case MCSymbolRefExpr::VK_GOTPCREL:
Type = ELF::R_X86_64_GOTPCREL;
break;
case MCSymbolRefExpr::VK_TPOFF:
Type = ELF::R_X86_64_TPOFF32;
break;
case MCSymbolRefExpr::VK_DTPOFF:
Type = ELF::R_X86_64_DTPOFF32;
break;
}
break;
case FK_Data_4:
Type = ELF::R_X86_64_32;
break;
case FK_Data_2: Type = ELF::R_X86_64_16; break;
case X86::reloc_pcrel_1byte:
case FK_Data_1: Type = ELF::R_X86_64_8; break;
}
}
} else {
if (IsPCRel) {
switch (Modifier) {
default:
llvm_unreachable("Unimplemented");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_386_PC32;
break;
case MCSymbolRefExpr::VK_PLT:
Type = ELF::R_386_PLT32;
break;
}
} else {
switch ((unsigned)Fixup.getKind()) {
default: llvm_unreachable("invalid fixup kind!");
case X86::reloc_global_offset_table:
Type = ELF::R_386_GOTPC;
break;
// FIXME: Should we avoid selecting reloc_signed_4byte in 32 bit mode
// instead?
case X86::reloc_signed_4byte:
case X86::reloc_pcrel_4byte:
case FK_Data_4:
switch (Modifier) {
default:
llvm_unreachable("Unimplemented");
case MCSymbolRefExpr::VK_None:
Type = ELF::R_386_32;
break;
case MCSymbolRefExpr::VK_GOT:
Type = ELF::R_386_GOT32;
break;
case MCSymbolRefExpr::VK_GOTOFF:
Type = ELF::R_386_GOTOFF;
break;
case MCSymbolRefExpr::VK_TLSGD:
Type = ELF::R_386_TLS_GD;
break;
case MCSymbolRefExpr::VK_TPOFF:
Type = ELF::R_386_TLS_LE_32;
break;
case MCSymbolRefExpr::VK_INDNTPOFF:
Type = ELF::R_386_TLS_IE;
break;
case MCSymbolRefExpr::VK_NTPOFF:
Type = ELF::R_386_TLS_LE;
break;
case MCSymbolRefExpr::VK_GOTNTPOFF:
Type = ELF::R_386_TLS_GOTIE;
break;
case MCSymbolRefExpr::VK_TLSLDM:
Type = ELF::R_386_TLS_LDM;
break;
case MCSymbolRefExpr::VK_DTPOFF:
Type = ELF::R_386_TLS_LDO_32;
break;
}
break;
case FK_Data_2: Type = ELF::R_386_16; break;
case X86::reloc_pcrel_1byte:
case FK_Data_1: Type = ELF::R_386_8; break;
}
}
}
if (RelocNeedsGOT(Modifier))
NeedsGOT = true;
ELFRelocationEntry ERE;
ERE.Index = Index;
ERE.Type = Type;
ERE.Symbol = RelocSymbol;
ERE.r_offset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
if (HasRelocationAddend)
ERE.r_addend = Addend;
else
ERE.r_addend = 0; // Silence compiler warning.
Relocations[Fragment->getParent()].push_back(ERE);
}
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