MachObjectWriter.cpp [plain text]
#include "llvm/MC/MachObjectWriter.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCMachOSymbolFlags.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MachO.h"
#include "llvm/Target/TargetAsmBackend.h"
#include "../Target/X86/X86FixupKinds.h"
#include <vector>
using namespace llvm;
static unsigned getFixupKindLog2Size(unsigned Kind) {
switch (Kind) {
default: llvm_unreachable("invalid fixup kind!");
case X86::reloc_pcrel_1byte:
case FK_Data_1: return 0;
case X86::reloc_pcrel_2byte:
case FK_Data_2: return 1;
case X86::reloc_pcrel_4byte:
case X86::reloc_riprel_4byte:
case X86::reloc_riprel_4byte_movq_load:
case X86::reloc_signed_4byte:
case FK_Data_4: return 2;
case FK_Data_8: return 3;
}
}
static bool isFixupKindPCRel(unsigned Kind) {
switch (Kind) {
default:
return false;
case X86::reloc_pcrel_1byte:
case X86::reloc_pcrel_2byte:
case X86::reloc_pcrel_4byte:
case X86::reloc_riprel_4byte:
case X86::reloc_riprel_4byte_movq_load:
return true;
}
}
static bool isFixupKindRIPRel(unsigned Kind) {
return Kind == X86::reloc_riprel_4byte ||
Kind == X86::reloc_riprel_4byte_movq_load;
}
static bool doesSymbolRequireExternRelocation(MCSymbolData *SD) {
if (SD->Symbol->isUndefined())
return true;
if (SD->getFlags() & SF_WeakDefinition)
return true;
return false;
}
static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
const MCValue Target,
const MCSymbolData *BaseSymbol) {
const MCSymbolData *A_Base = 0, *B_Base = 0;
if (const MCSymbolRefExpr *A = Target.getSymA()) {
if (A->getKind() != MCSymbolRefExpr::VK_None)
return false;
A_Base = Asm.getAtom(&Asm.getSymbolData(A->getSymbol()));
if (!A_Base)
return false;
}
if (const MCSymbolRefExpr *B = Target.getSymB()) {
if (B->getKind() != MCSymbolRefExpr::VK_None)
return false;
B_Base = Asm.getAtom(&Asm.getSymbolData(B->getSymbol()));
if (!B_Base)
return false;
}
if (!BaseSymbol)
return A_Base == B_Base;
return !B_Base && BaseSymbol == A_Base;
}
static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
const MCValue Target,
const MCSection *BaseSection) {
if (!BaseSection)
return Target.isAbsolute();
if (Target.isAbsolute() || Target.getSymB())
return false;
const MCSymbol *A = &Target.getSymA()->getSymbol();
if (!A->isTemporary() || !A->isInSection() ||
&A->getSection() != BaseSection)
return false;
return true;
}
namespace {
class MachObjectWriterImpl {
enum {
Header_Magic32 = 0xFEEDFACE,
Header_Magic64 = 0xFEEDFACF
};
enum {
Header32Size = 28,
Header64Size = 32,
SegmentLoadCommand32Size = 56,
SegmentLoadCommand64Size = 72,
Section32Size = 68,
Section64Size = 80,
SymtabLoadCommandSize = 24,
DysymtabLoadCommandSize = 80,
Nlist32Size = 12,
Nlist64Size = 16,
RelocationInfoSize = 8
};
enum HeaderFileType {
HFT_Object = 0x1
};
enum HeaderFlags {
HF_SubsectionsViaSymbols = 0x2000
};
enum LoadCommandType {
LCT_Segment = 0x1,
LCT_Symtab = 0x2,
LCT_Dysymtab = 0xb,
LCT_Segment64 = 0x19
};
enum SymbolTypeType {
STT_Undefined = 0x00,
STT_Absolute = 0x02,
STT_Section = 0x0e
};
enum SymbolTypeFlags {
STF_StabsEntryMask = 0xe0,
STF_TypeMask = 0x0e,
STF_External = 0x01,
STF_PrivateExtern = 0x10
};
enum IndirectSymbolFlags {
ISF_Local = 0x80000000,
ISF_Absolute = 0x40000000
};
enum RelocationFlags {
RF_Scattered = 0x80000000
};
enum RelocationInfoType {
RIT_Vanilla = 0,
RIT_Pair = 1,
RIT_Difference = 2,
RIT_PreboundLazyPointer = 3,
RIT_LocalDifference = 4,
RIT_TLV = 5
};
enum RelocationInfoTypeX86_64 {
RIT_X86_64_Unsigned = 0,
RIT_X86_64_Signed = 1,
RIT_X86_64_Branch = 2,
RIT_X86_64_GOTLoad = 3,
RIT_X86_64_GOT = 4,
RIT_X86_64_Subtractor = 5,
RIT_X86_64_Signed1 = 6,
RIT_X86_64_Signed2 = 7,
RIT_X86_64_Signed4 = 8,
RIT_X86_64_TLV = 9
};
struct MachSymbolData {
MCSymbolData *SymbolData;
uint64_t StringIndex;
uint8_t SectionIndex;
bool operator<(const MachSymbolData &RHS) const {
return SymbolData->getSymbol().getName() <
RHS.SymbolData->getSymbol().getName();
}
};
struct MachRelocationEntry {
uint32_t Word0;
uint32_t Word1;
};
llvm::DenseMap<const MCSectionData*,
std::vector<MachRelocationEntry> > Relocations;
llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase;
SmallString<256> StringTable;
std::vector<MachSymbolData> LocalSymbolData;
std::vector<MachSymbolData> ExternalSymbolData;
std::vector<MachSymbolData> UndefinedSymbolData;
MachObjectWriter *Writer;
raw_ostream &OS;
unsigned Is64Bit : 1;
public:
MachObjectWriterImpl(MachObjectWriter *_Writer, bool _Is64Bit)
: Writer(_Writer), OS(Writer->getStream()), Is64Bit(_Is64Bit) {
}
void Write8(uint8_t Value) { Writer->Write8(Value); }
void Write16(uint16_t Value) { Writer->Write16(Value); }
void Write32(uint32_t Value) { Writer->Write32(Value); }
void Write64(uint64_t Value) { Writer->Write64(Value); }
void WriteZeros(unsigned N) { Writer->WriteZeros(N); }
void WriteBytes(StringRef Str, unsigned ZeroFillSize = 0) {
Writer->WriteBytes(Str, ZeroFillSize);
}
void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize,
bool SubsectionsViaSymbols) {
uint32_t Flags = 0;
if (SubsectionsViaSymbols)
Flags |= HF_SubsectionsViaSymbols;
uint64_t Start = OS.tell();
(void) Start;
Write32(Is64Bit ? Header_Magic64 : Header_Magic32);
Write32(Is64Bit ? MachO::CPUTypeX86_64 : MachO::CPUTypeI386);
Write32(MachO::CPUSubType_I386_ALL);
Write32(HFT_Object);
Write32(NumLoadCommands); Write32(LoadCommandsSize);
Write32(Flags);
if (Is64Bit)
Write32(0);
assert(OS.tell() - Start == Is64Bit ? Header64Size : Header32Size);
}
void WriteSegmentLoadCommand(unsigned NumSections,
uint64_t VMSize,
uint64_t SectionDataStartOffset,
uint64_t SectionDataSize) {
uint64_t Start = OS.tell();
(void) Start;
unsigned SegmentLoadCommandSize = Is64Bit ? SegmentLoadCommand64Size :
SegmentLoadCommand32Size;
Write32(Is64Bit ? LCT_Segment64 : LCT_Segment);
Write32(SegmentLoadCommandSize +
NumSections * (Is64Bit ? Section64Size : Section32Size));
WriteBytes("", 16);
if (Is64Bit) {
Write64(0); Write64(VMSize); Write64(SectionDataStartOffset); Write64(SectionDataSize); } else {
Write32(0); Write32(VMSize); Write32(SectionDataStartOffset); Write32(SectionDataSize); }
Write32(0x7); Write32(0x7); Write32(NumSections);
Write32(0);
assert(OS.tell() - Start == SegmentLoadCommandSize);
}
void WriteSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCSectionData &SD, uint64_t FileOffset,
uint64_t RelocationsStart, unsigned NumRelocations) {
uint64_t SectionSize = Layout.getSectionSize(&SD);
if (Asm.getBackend().isVirtualSection(SD.getSection())) {
assert(Layout.getSectionFileSize(&SD) == 0 && "Invalid file size!");
FileOffset = 0;
}
uint64_t Start = OS.tell();
(void) Start;
const MCSectionMachO &Section = cast<MCSectionMachO>(SD.getSection());
WriteBytes(Section.getSectionName(), 16);
WriteBytes(Section.getSegmentName(), 16);
if (Is64Bit) {
Write64(Layout.getSectionAddress(&SD)); Write64(SectionSize); } else {
Write32(Layout.getSectionAddress(&SD)); Write32(SectionSize); }
Write32(FileOffset);
unsigned Flags = Section.getTypeAndAttributes();
if (SD.hasInstructions())
Flags |= MCSectionMachO::S_ATTR_SOME_INSTRUCTIONS;
assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
Write32(Log2_32(SD.getAlignment()));
Write32(NumRelocations ? RelocationsStart : 0);
Write32(NumRelocations);
Write32(Flags);
Write32(IndirectSymBase.lookup(&SD)); Write32(Section.getStubSize()); if (Is64Bit)
Write32(0);
assert(OS.tell() - Start == Is64Bit ? Section64Size : Section32Size);
}
void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
uint32_t StringTableOffset,
uint32_t StringTableSize) {
uint64_t Start = OS.tell();
(void) Start;
Write32(LCT_Symtab);
Write32(SymtabLoadCommandSize);
Write32(SymbolOffset);
Write32(NumSymbols);
Write32(StringTableOffset);
Write32(StringTableSize);
assert(OS.tell() - Start == SymtabLoadCommandSize);
}
void WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol,
uint32_t NumLocalSymbols,
uint32_t FirstExternalSymbol,
uint32_t NumExternalSymbols,
uint32_t FirstUndefinedSymbol,
uint32_t NumUndefinedSymbols,
uint32_t IndirectSymbolOffset,
uint32_t NumIndirectSymbols) {
uint64_t Start = OS.tell();
(void) Start;
Write32(LCT_Dysymtab);
Write32(DysymtabLoadCommandSize);
Write32(FirstLocalSymbol);
Write32(NumLocalSymbols);
Write32(FirstExternalSymbol);
Write32(NumExternalSymbols);
Write32(FirstUndefinedSymbol);
Write32(NumUndefinedSymbols);
Write32(0); Write32(0); Write32(0); Write32(0); Write32(0); Write32(0); Write32(IndirectSymbolOffset);
Write32(NumIndirectSymbols);
Write32(0); Write32(0); Write32(0); Write32(0);
assert(OS.tell() - Start == DysymtabLoadCommandSize);
}
void WriteNlist(MachSymbolData &MSD, const MCAsmLayout &Layout) {
MCSymbolData &Data = *MSD.SymbolData;
const MCSymbol &Symbol = Data.getSymbol();
uint8_t Type = 0;
uint16_t Flags = Data.getFlags();
uint32_t Address = 0;
if (Symbol.isUndefined())
Type = STT_Undefined;
else if (Symbol.isAbsolute())
Type = STT_Absolute;
else
Type = STT_Section;
if (Data.isPrivateExtern())
Type |= STF_PrivateExtern;
if (Data.isExternal() || Symbol.isUndefined())
Type |= STF_External;
if (Symbol.isDefined()) {
if (Symbol.isAbsolute()) {
Address = cast<MCConstantExpr>(Symbol.getVariableValue())->getValue();
} else {
Address = Layout.getSymbolAddress(&Data);
}
} else if (Data.isCommon()) {
Address = Data.getCommonSize();
if (unsigned Align = Data.getCommonAlignment()) {
unsigned Log2Size = Log2_32(Align);
assert((1U << Log2Size) == Align && "Invalid 'common' alignment!");
if (Log2Size > 15)
report_fatal_error("invalid 'common' alignment '" +
Twine(Align) + "'");
Flags = (Flags & 0xF0FF) | (Log2Size << 8);
}
}
Write32(MSD.StringIndex);
Write8(Type);
Write8(MSD.SectionIndex);
Write16(Flags);
if (Is64Bit)
Write64(Address);
else
Write32(Address);
}
void RecordX86_64Relocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) {
unsigned IsPCRel = isFixupKindPCRel(Fixup.getKind());
unsigned IsRIPRel = isFixupKindRIPRel(Fixup.getKind());
unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
uint32_t FixupOffset =
Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
uint32_t FixupAddress =
Layout.getFragmentAddress(Fragment) + Fixup.getOffset();
int64_t Value = 0;
unsigned Index = 0;
unsigned IsExtern = 0;
unsigned Type = 0;
Value = Target.getConstant();
if (IsPCRel) {
Value += 1LL << Log2Size;
}
if (Target.isAbsolute()) { Type = RIT_X86_64_Unsigned;
Index = 0;
if (IsPCRel) {
IsExtern = 1;
Type = RIT_X86_64_Branch;
}
} else if (Target.getSymB()) { const MCSymbol *A = &Target.getSymA()->getSymbol();
MCSymbolData &A_SD = Asm.getSymbolData(*A);
const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
const MCSymbol *B = &Target.getSymB()->getSymbol();
MCSymbolData &B_SD = Asm.getSymbolData(*B);
const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None ||
Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None)
report_fatal_error("unsupported relocation of modified symbol");
if (IsPCRel)
report_fatal_error("unsupported pc-relative relocation of difference");
if (A_Base == B_Base && A_Base)
report_fatal_error("unsupported relocation with identical base");
Value += Layout.getSymbolAddress(&A_SD) -
(A_Base == NULL ? 0 : Layout.getSymbolAddress(A_Base));
Value -= Layout.getSymbolAddress(&B_SD) -
(B_Base == NULL ? 0 : Layout.getSymbolAddress(B_Base));
if (A_Base) {
Index = A_Base->getIndex();
IsExtern = 1;
}
else {
Index = A_SD.getFragment()->getParent()->getOrdinal() + 1;
IsExtern = 0;
}
Type = RIT_X86_64_Unsigned;
MachRelocationEntry MRE;
MRE.Word0 = FixupOffset;
MRE.Word1 = ((Index << 0) |
(IsPCRel << 24) |
(Log2Size << 25) |
(IsExtern << 27) |
(Type << 28));
Relocations[Fragment->getParent()].push_back(MRE);
if (B_Base) {
Index = B_Base->getIndex();
IsExtern = 1;
}
else {
Index = B_SD.getFragment()->getParent()->getOrdinal() + 1;
IsExtern = 0;
}
Type = RIT_X86_64_Subtractor;
} else {
const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
MCSymbolData &SD = Asm.getSymbolData(*Symbol);
const MCSymbolData *Base = Asm.getAtom(&SD);
if (Symbol->isInSection()) {
const MCSectionMachO &Section = static_cast<const MCSectionMachO&>(
Fragment->getParent()->getSection());
if (Section.hasAttribute(MCSectionMachO::S_ATTR_DEBUG))
Base = 0;
}
if (Base) {
Index = Base->getIndex();
IsExtern = 1;
if (Base != &SD)
Value += Layout.getSymbolAddress(&SD) - Layout.getSymbolAddress(Base);
} else if (Symbol->isInSection()) {
Index = SD.getFragment()->getParent()->getOrdinal() + 1;
IsExtern = 0;
Value += Layout.getSymbolAddress(&SD);
if (IsPCRel)
Value -= FixupAddress + (1 << Log2Size);
} else {
report_fatal_error("unsupported relocation of undefined symbol '" +
Symbol->getName() + "'");
}
MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
if (IsPCRel) {
if (IsRIPRel) {
if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load)
Type = RIT_X86_64_GOTLoad;
else
Type = RIT_X86_64_GOT;
} else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
Type = RIT_X86_64_TLV;
} else if (Modifier != MCSymbolRefExpr::VK_None) {
report_fatal_error("unsupported symbol modifier in relocation");
} else {
Type = RIT_X86_64_Signed;
switch (-(Target.getConstant() + (1LL << Log2Size))) {
case 1: Type = RIT_X86_64_Signed1; break;
case 2: Type = RIT_X86_64_Signed2; break;
case 4: Type = RIT_X86_64_Signed4; break;
}
}
} else {
if (Modifier != MCSymbolRefExpr::VK_None)
report_fatal_error("unsupported symbol modifier in branch "
"relocation");
Type = RIT_X86_64_Branch;
}
} else {
if (Modifier == MCSymbolRefExpr::VK_GOT) {
Type = RIT_X86_64_GOT;
} else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
Type = RIT_X86_64_GOT;
IsPCRel = 1;
} else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
report_fatal_error("TLVP symbol modifier should have been rip-rel");
} else if (Modifier != MCSymbolRefExpr::VK_None)
report_fatal_error("unsupported symbol modifier in relocation");
else
Type = RIT_X86_64_Unsigned;
}
}
FixedValue = Value;
MachRelocationEntry MRE;
MRE.Word0 = FixupOffset;
MRE.Word1 = ((Index << 0) |
(IsPCRel << 24) |
(Log2Size << 25) |
(IsExtern << 27) |
(Type << 28));
Relocations[Fragment->getParent()].push_back(MRE);
}
void RecordScatteredRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) {
uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
unsigned IsPCRel = isFixupKindPCRel(Fixup.getKind());
unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
unsigned Type = RIT_Vanilla;
const MCSymbol *A = &Target.getSymA()->getSymbol();
MCSymbolData *A_SD = &Asm.getSymbolData(*A);
if (!A_SD->getFragment())
report_fatal_error("symbol '" + A->getName() +
"' can not be undefined in a subtraction expression");
uint32_t Value = Layout.getSymbolAddress(A_SD);
uint32_t Value2 = 0;
if (const MCSymbolRefExpr *B = Target.getSymB()) {
MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
if (!B_SD->getFragment())
report_fatal_error("symbol '" + B->getSymbol().getName() +
"' can not be undefined in a subtraction expression");
Type = A_SD->isExternal() ? RIT_Difference : RIT_LocalDifference;
Value2 = Layout.getSymbolAddress(B_SD);
}
if (Type == RIT_Difference || Type == RIT_LocalDifference) {
MachRelocationEntry MRE;
MRE.Word0 = ((0 << 0) |
(RIT_Pair << 24) |
(Log2Size << 28) |
(IsPCRel << 30) |
RF_Scattered);
MRE.Word1 = Value2;
Relocations[Fragment->getParent()].push_back(MRE);
}
MachRelocationEntry MRE;
MRE.Word0 = ((FixupOffset << 0) |
(Type << 24) |
(Log2Size << 28) |
(IsPCRel << 30) |
RF_Scattered);
MRE.Word1 = Value;
Relocations[Fragment->getParent()].push_back(MRE);
}
void RecordTLVPRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) {
assert(Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP &&
!Is64Bit &&
"Should only be called with a 32-bit TLVP relocation!");
unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
uint32_t Value = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
unsigned IsPCRel = 0;
MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol());
unsigned Index = SD_A->getIndex();
if (Target.getSymB()) {
uint32_t FixupAddress =
Layout.getFragmentAddress(Fragment) + Fixup.getOffset();
MCSymbolData *SD_B = &Asm.getSymbolData(Target.getSymB()->getSymbol());
IsPCRel = 1;
FixedValue = (FixupAddress - Layout.getSymbolAddress(SD_B) +
Target.getConstant());
FixedValue += 1ULL << Log2Size;
} else {
FixedValue = 0;
}
MachRelocationEntry MRE;
MRE.Word0 = Value;
MRE.Word1 = ((Index << 0) |
(IsPCRel << 24) |
(Log2Size << 25) |
(1 << 27) | (RIT_TLV << 28)); Relocations[Fragment->getParent()].push_back(MRE);
}
void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment, const MCFixup &Fixup,
MCValue Target, uint64_t &FixedValue) {
if (Is64Bit) {
RecordX86_64Relocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
return;
}
unsigned IsPCRel = isFixupKindPCRel(Fixup.getKind());
unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
if (Target.getSymA() &&
Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP) {
RecordTLVPRelocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
return;
}
if (Target.getSymB())
return RecordScatteredRelocation(Asm, Layout, Fragment, Fixup,
Target, FixedValue);
MCSymbolData *SD = 0;
if (Target.getSymA())
SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
uint32_t Offset = Target.getConstant();
if (IsPCRel)
Offset += 1 << Log2Size;
if (Offset && SD && !doesSymbolRequireExternRelocation(SD))
return RecordScatteredRelocation(Asm, Layout, Fragment, Fixup,
Target, FixedValue);
uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
unsigned Index = 0;
unsigned IsExtern = 0;
unsigned Type = 0;
if (Target.isAbsolute()) { Type = RIT_Vanilla;
} else {
if (doesSymbolRequireExternRelocation(SD)) {
IsExtern = 1;
Index = SD->getIndex();
if (!SD->Symbol->isUndefined())
FixedValue -= Layout.getSymbolAddress(SD);
} else {
Index = SD->getFragment()->getParent()->getOrdinal() + 1;
}
Type = RIT_Vanilla;
}
MachRelocationEntry MRE;
MRE.Word0 = FixupOffset;
MRE.Word1 = ((Index << 0) |
(IsPCRel << 24) |
(Log2Size << 25) |
(IsExtern << 27) |
(Type << 28));
Relocations[Fragment->getParent()].push_back(MRE);
}
void BindIndirectSymbols(MCAssembler &Asm) {
unsigned IndirectIndex = 0;
for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
const MCSectionMachO &Section =
cast<MCSectionMachO>(it->SectionData->getSection());
if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS)
continue;
if (!IndirectSymBase.count(it->SectionData))
IndirectSymBase[it->SectionData] = IndirectIndex;
Asm.getOrCreateSymbolData(*it->Symbol);
}
IndirectIndex = 0;
for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
const MCSectionMachO &Section =
cast<MCSectionMachO>(it->SectionData->getSection());
if (Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS &&
Section.getType() != MCSectionMachO::S_SYMBOL_STUBS)
continue;
if (!IndirectSymBase.count(it->SectionData))
IndirectSymBase[it->SectionData] = IndirectIndex;
bool Created;
MCSymbolData &Entry = Asm.getOrCreateSymbolData(*it->Symbol, &Created);
if (Created)
Entry.setFlags(Entry.getFlags() | 0x0001);
}
}
void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
std::vector<MachSymbolData> &LocalSymbolData,
std::vector<MachSymbolData> &ExternalSymbolData,
std::vector<MachSymbolData> &UndefinedSymbolData) {
DenseMap<const MCSection*, uint8_t> SectionIndexMap;
unsigned Index = 1;
for (MCAssembler::iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it, ++Index)
SectionIndexMap[&it->getSection()] = Index;
assert(Index <= 256 && "Too many sections!");
StringMap<uint64_t> StringIndexMap;
StringTable += '\x00';
for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
ie = Asm.symbol_end(); it != ie; ++it) {
const MCSymbol &Symbol = it->getSymbol();
if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
continue;
if (!it->isExternal() && !Symbol.isUndefined())
continue;
uint64_t &Entry = StringIndexMap[Symbol.getName()];
if (!Entry) {
Entry = StringTable.size();
StringTable += Symbol.getName();
StringTable += '\x00';
}
MachSymbolData MSD;
MSD.SymbolData = it;
MSD.StringIndex = Entry;
if (Symbol.isUndefined()) {
MSD.SectionIndex = 0;
UndefinedSymbolData.push_back(MSD);
} else if (Symbol.isAbsolute()) {
MSD.SectionIndex = 0;
ExternalSymbolData.push_back(MSD);
} else {
MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
assert(MSD.SectionIndex && "Invalid section index!");
ExternalSymbolData.push_back(MSD);
}
}
for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
ie = Asm.symbol_end(); it != ie; ++it) {
const MCSymbol &Symbol = it->getSymbol();
if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
continue;
if (it->isExternal() || Symbol.isUndefined())
continue;
uint64_t &Entry = StringIndexMap[Symbol.getName()];
if (!Entry) {
Entry = StringTable.size();
StringTable += Symbol.getName();
StringTable += '\x00';
}
MachSymbolData MSD;
MSD.SymbolData = it;
MSD.StringIndex = Entry;
if (Symbol.isAbsolute()) {
MSD.SectionIndex = 0;
LocalSymbolData.push_back(MSD);
} else {
MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
assert(MSD.SectionIndex && "Invalid section index!");
LocalSymbolData.push_back(MSD);
}
}
std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
Index = 0;
for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
LocalSymbolData[i].SymbolData->setIndex(Index++);
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++);
while (StringTable.size() % 4)
StringTable += '\x00';
}
void ExecutePostLayoutBinding(MCAssembler &Asm) {
BindIndirectSymbols(Asm);
ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
UndefinedSymbolData);
}
bool IsFixupFullyResolved(const MCAssembler &Asm,
const MCValue Target,
bool IsPCRel,
const MCFragment *DF) const {
if (Asm.getBackend().hasScatteredSymbols()) {
if (Asm.getBackend().hasReliableSymbolDifference()) {
const MCSymbolData *BaseSymbol = 0;
if (IsPCRel) {
BaseSymbol = DF->getAtom();
if (!BaseSymbol)
return false;
}
return isScatteredFixupFullyResolved(Asm, Target, BaseSymbol);
} else {
const MCSection *BaseSection = 0;
if (IsPCRel)
BaseSection = &DF->getParent()->getSection();
return isScatteredFixupFullyResolvedSimple(Asm, Target, BaseSection);
}
}
return true;
}
void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout) {
unsigned NumSections = Asm.size();
unsigned NumLoadCommands = 1;
uint64_t LoadCommandsSize = Is64Bit ?
SegmentLoadCommand64Size + NumSections * Section64Size :
SegmentLoadCommand32Size + NumSections * Section32Size;
unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
UndefinedSymbolData.size();
if (NumSymbols) {
NumLoadCommands += 2;
LoadCommandsSize += SymtabLoadCommandSize + DysymtabLoadCommandSize;
}
uint64_t SectionDataStart = (Is64Bit ? Header64Size : Header32Size)
+ LoadCommandsSize;
uint64_t SectionDataSize = 0;
uint64_t SectionDataFileSize = 0;
uint64_t VMSize = 0;
for (MCAssembler::const_iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
const MCSectionData &SD = *it;
uint64_t Address = Layout.getSectionAddress(&SD);
uint64_t Size = Layout.getSectionSize(&SD);
uint64_t FileSize = Layout.getSectionFileSize(&SD);
VMSize = std::max(VMSize, Address + Size);
if (Asm.getBackend().isVirtualSection(SD.getSection()))
continue;
SectionDataSize = std::max(SectionDataSize, Address + Size);
SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
}
unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
SectionDataFileSize += SectionDataPadding;
WriteHeader(NumLoadCommands, LoadCommandsSize,
Asm.getSubsectionsViaSymbols());
WriteSegmentLoadCommand(NumSections, VMSize,
SectionDataStart, SectionDataSize);
uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
for (MCAssembler::const_iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
std::vector<MachRelocationEntry> &Relocs = Relocations[it];
unsigned NumRelocs = Relocs.size();
uint64_t SectionStart = SectionDataStart + Layout.getSectionAddress(it);
WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
RelocTableEnd += NumRelocs * RelocationInfoSize;
}
if (NumSymbols) {
unsigned FirstLocalSymbol = 0;
unsigned NumLocalSymbols = LocalSymbolData.size();
unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
unsigned NumExternalSymbols = ExternalSymbolData.size();
unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
unsigned NumSymTabSymbols =
NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
uint64_t IndirectSymbolOffset = 0;
if (NumIndirectSymbols)
IndirectSymbolOffset = RelocTableEnd;
uint64_t SymbolTableOffset = RelocTableEnd + IndirectSymbolSize;
uint64_t StringTableOffset =
SymbolTableOffset + NumSymTabSymbols * (Is64Bit ? Nlist64Size :
Nlist32Size);
WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
StringTableOffset, StringTable.size());
WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
FirstExternalSymbol, NumExternalSymbols,
FirstUndefinedSymbol, NumUndefinedSymbols,
IndirectSymbolOffset, NumIndirectSymbols);
}
for (MCAssembler::const_iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it)
Asm.WriteSectionData(it, Layout, Writer);
WriteZeros(SectionDataPadding);
for (MCAssembler::const_iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it) {
std::vector<MachRelocationEntry> &Relocs = Relocations[it];
for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
Write32(Relocs[e - i - 1].Word0);
Write32(Relocs[e - i - 1].Word1);
}
}
if (NumSymbols) {
for (MCAssembler::const_indirect_symbol_iterator
it = Asm.indirect_symbol_begin(),
ie = Asm.indirect_symbol_end(); it != ie; ++it) {
const MCSectionMachO &Section =
static_cast<const MCSectionMachO&>(it->SectionData->getSection());
if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) {
if (it->Symbol->isDefined() &&
!Asm.getSymbolData(*it->Symbol).isExternal()) {
uint32_t Flags = ISF_Local;
if (it->Symbol->isAbsolute())
Flags |= ISF_Absolute;
Write32(Flags);
continue;
}
}
Write32(Asm.getSymbolData(*it->Symbol).getIndex());
}
for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
WriteNlist(LocalSymbolData[i], Layout);
for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
WriteNlist(ExternalSymbolData[i], Layout);
for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
WriteNlist(UndefinedSymbolData[i], Layout);
OS << StringTable.str();
}
}
};
}
MachObjectWriter::MachObjectWriter(raw_ostream &OS,
bool Is64Bit,
bool IsLittleEndian)
: MCObjectWriter(OS, IsLittleEndian)
{
Impl = new MachObjectWriterImpl(this, Is64Bit);
}
MachObjectWriter::~MachObjectWriter() {
delete (MachObjectWriterImpl*) Impl;
}
void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm) {
((MachObjectWriterImpl*) Impl)->ExecutePostLayoutBinding(Asm);
}
void MachObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) {
((MachObjectWriterImpl*) Impl)->RecordRelocation(Asm, Layout, Fragment, Fixup,
Target, FixedValue);
}
bool MachObjectWriter::IsFixupFullyResolved(const MCAssembler &Asm,
const MCValue Target,
bool IsPCRel,
const MCFragment *DF) const {
return ((MachObjectWriterImpl*) Impl)->IsFixupFullyResolved(Asm, Target,
IsPCRel, DF);
}
void MachObjectWriter::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
((MachObjectWriterImpl*) Impl)->WriteObject(Asm, Layout);
}