//===----------------------------------------------------------------------===//
#include "llvm/MC/ELFObjectWriter.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Twine.h"
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(unsigned Type) {
+ switch (Type) {
+ default:
+ return false;
+ case ELF::R_X86_64_GOT32:
+ case ELF::R_X86_64_PLT32:
+ case ELF::R_X86_64_GOTPCREL:
+ return true;
+ }
+}
+
namespace {
class ELFObjectWriterImpl {
- 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 isFixupKindX86RIPRel(unsigned Kind) {
return Kind == X86::reloc_riprel_4byte ||
Kind == X86::reloc_riprel_4byte_movq_load;
struct ELFRelocationEntry {
// Make these big enough for both 32-bit and 64-bit
uint64_t r_offset;
- uint64_t r_info;
+ int Index;
+ unsigned Type;
+ const MCSymbol *Symbol;
uint64_t r_addend;
// Support lexicographic sorting.
}
};
+ SmallPtrSet<const MCSymbol *, 16> UsedInReloc;
+
llvm::DenseMap<const MCSectionData*,
std::vector<ELFRelocationEntry> > Relocations;
DenseMap<const MCSection*, uint64_t> SectionStringTableIndex;
/// @}
+ int NumRegularSections;
+
+ bool NeedsGOT;
+
ELFObjectWriter *Writer;
raw_ostream &OS;
public:
ELFObjectWriterImpl(ELFObjectWriter *_Writer, bool _Is64Bit,
bool _HasRelAddend, Triple::OSType _OSType)
- : Writer(_Writer), OS(Writer->getStream()),
+ : NeedsGOT(false), Writer(_Writer), OS(Writer->getStream()),
Is64Bit(_Is64Bit), HasRelocationAddend(_HasRelAddend),
OSType(_OSType) {
}
void CreateMetadataSections(MCAssembler &Asm, MCAsmLayout &Layout);
void ExecutePostLayoutBinding(MCAssembler &Asm) {
- // Compute symbol table information.
- ComputeSymbolTable(Asm);
}
void WriteSecHdrEntry(uint32_t Name, uint32_t Type, uint64_t Flags,
bool IsPCRel,
const MCFragment *DF) const;
- void WriteObject(const MCAssembler &Asm, const MCAsmLayout &Layout);
+ void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
};
}
return 0;
}
+static const MCSymbol &AliasedSymbol(const MCSymbol &Symbol) {
+ const MCSymbol *S = &Symbol;
+ while (S->isVariable()) {
+ const MCExpr *Value = S->getVariableValue();
+ assert (Value->getKind() == MCExpr::SymbolRef && "Unimplemented");
+ const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
+ S = &Ref->getSymbol();
+ }
+ return *S;
+}
+
void ELFObjectWriterImpl::WriteSymbol(MCDataFragment *F, ELFSymbolData &MSD,
const MCAsmLayout &Layout) {
- MCSymbolData &Data = *MSD.SymbolData;
- uint8_t Info = (Data.getFlags() & 0xff);
- uint8_t Other = ((Data.getFlags() & 0xf00) >> ELF_STV_Shift);
+ MCSymbolData &OrigData = *MSD.SymbolData;
+ MCSymbolData &Data =
+ Layout.getAssembler().getSymbolData(AliasedSymbol(OrigData.getSymbol()));
+
+ 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;
const MCBinaryExpr *BE = static_cast<const MCBinaryExpr *>(ESize);
if (BE->EvaluateAsRelocatable(Res, &Layout)) {
- MCSymbolData &A =
- Layout.getAssembler().getSymbolData(Res.getSymA()->getSymbol());
- MCSymbolData &B =
- Layout.getAssembler().getSymbolData(Res.getSymB()->getSymbol());
-
- Size = Layout.getSymbolAddress(&A) - Layout.getSymbolAddress(&B);
+ 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();
for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) {
ELFSymbolData &MSD = ExternalSymbolData[i];
MCSymbolData &Data = *MSD.SymbolData;
- assert((Data.getFlags() & ELF_STB_Global) &&
- "External symbol requires STB_GLOBAL flag");
+ assert(((Data.getFlags() & ELF_STB_Global) ||
+ (Data.getFlags() & ELF_STB_Weak)) &&
+ "External symbol requires STB_GLOBAL or STB_WEAK flag");
WriteSymbol(F, MSD, Layout);
if (GetBinding(Data) == ELF::STB_LOCAL)
LastLocalSymbolIndex++;
}
static bool ShouldRelocOnSymbol(const MCSymbolData &SD,
- const MCValue &Target) {
+ const MCValue &Target,
+ const MCFragment &F) {
const MCSymbol &Symbol = SD.getSymbol();
if (Symbol.isUndefined())
return true;
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(Symbol.getSection());
- if (Section.getFlags() & MCSectionELF::SHF_MERGE)
- return Target.getConstant() != 0;
-
if (SD.isExternal())
return true;
+ 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))
+ return true;
+
+ if (Section.getFlags() & MCSectionELF::SHF_MERGE)
+ return Target.getConstant() != 0;
+
return false;
}
MCValue Target,
uint64_t &FixedValue) {
int64_t Addend = 0;
- unsigned Index = 0;
+ int Index = 0;
int64_t Value = Target.getConstant();
+ const MCSymbol *Symbol = 0;
bool IsPCRel = isFixupKindX86PCRel(Fixup.getKind());
if (!Target.isAbsolute()) {
- const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
+ Symbol = &AliasedSymbol(Target.getSymA()->getSymbol());
MCSymbolData &SD = Asm.getSymbolData(*Symbol);
MCFragment *F = SD.getFragment();
const MCSymbol &SymbolB = RefB->getSymbol();
MCSymbolData &SDB = Asm.getSymbolData(SymbolB);
IsPCRel = true;
- Value += Layout.getFragmentOffset(Fragment) + Fixup.getOffset() - Layout.getSymbolAddress(&SDB);
+ 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;
}
// Check that this case has already been fully resolved before we get
return;
}
- bool RelocOnSymbol = ShouldRelocOnSymbol(SD, Target);
+ bool RelocOnSymbol = ShouldRelocOnSymbol(SD, Target, *Fragment);
if (!RelocOnSymbol) {
- Index = F->getParent()->getOrdinal() + LocalSymbolData.size() + 1;
+ Index = F->getParent()->getOrdinal();
MCSectionData *FSD = F->getParent();
// Offset of the symbol in the section
Value += Layout.getSymbolAddress(&SD) - Layout.getSectionAddress(FSD);
- } else
- Index = getSymbolIndexInSymbolTable(Asm, Symbol);
+ } else {
+ UsedInReloc.insert(Symbol);
+ Index = -1;
+ }
Addend = Value;
// Compensate for the addend on i386.
if (Is64Bit)
FixedValue = Value;
// determine the type of the relocation
+
+ MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
unsigned Type;
if (Is64Bit) {
if (IsPCRel) {
- Type = ELF::R_X86_64_PC32;
+ 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 llvm::MCSymbolRefExpr::VK_GOTPCREL:
+ Type = ELF::R_X86_64_GOTPCREL;
+ break;
+ }
} else {
switch ((unsigned)Fixup.getKind()) {
default: llvm_unreachable("invalid fixup kind!");
case X86::reloc_signed_4byte:
case X86::reloc_pcrel_4byte:
assert(isInt<32>(Target.getConstant()));
- Type = ELF::R_X86_64_32S;
+ 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;
+ }
break;
case FK_Data_4:
Type = ELF::R_X86_64_32;
}
} else {
if (IsPCRel) {
- Type = ELF::R_386_PC32;
+ switch (Modifier) {
+ default:
+ Type = ELF::R_386_PC32;
+ //llvm_unreachable("Unimplemented");
+ break;
+ case MCSymbolRefExpr::VK_PLT:
+ Type = ELF::R_386_PLT32;
+ break;
+ }
} else {
switch ((unsigned)Fixup.getKind()) {
default: llvm_unreachable("invalid fixup kind!");
// instead?
case X86::reloc_signed_4byte:
case X86::reloc_pcrel_4byte:
+ switch (Modifier) {
+ default:
+ llvm_unreachable("Unimplemented");
+ case MCSymbolRefExpr::VK_GOTOFF:
+ Type = ELF::R_386_GOTOFF;
+ break;
+ }
+ break;
case FK_Data_4: Type = ELF::R_386_32; break;
case FK_Data_2: Type = ELF::R_386_16; break;
case X86::reloc_pcrel_1byte:
}
}
+ if (RelocNeedsGOT(Type))
+ NeedsGOT = true;
+
ELFRelocationEntry ERE;
- if (Is64Bit) {
- struct ELF::Elf64_Rela ERE64;
- ERE64.setSymbolAndType(Index, Type);
- ERE.r_info = ERE64.r_info;
- } else {
- struct ELF::Elf32_Rela ERE32;
- ERE32.setSymbolAndType(Index, Type);
- ERE.r_info = ERE32.r_info;
- }
+ ERE.Index = Index;
+ ERE.Type = Type;
+ ERE.Symbol = Symbol;
ERE.r_offset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
return SD.getIndex() + /* empty symbol */ 1;
// External or undefined symbol.
- return SD.getIndex() + Asm.size() + /* empty symbol */ 1;
+ return SD.getIndex() + NumRegularSections + /* empty symbol */ 1;
+}
+
+static bool isInSymtab(const MCAssembler &Asm, const MCSymbolData &Data,
+ bool Used) {
+ const MCSymbol &Symbol = Data.getSymbol();
+ if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
+ return false;
+
+ if (!Used && Symbol.isTemporary())
+ return false;
+
+ return true;
+}
+
+static bool isLocal(const MCSymbolData &Data) {
+ if (Data.isExternal())
+ return false;
+
+ const MCSymbol &Symbol = Data.getSymbol();
+ if (Symbol.isUndefined() && !Symbol.isVariable())
+ return false;
+
+ return true;
}
void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
+ // 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);
+ }
+
// Build section lookup table.
- DenseMap<const MCSection*, uint8_t> SectionIndexMap;
+ NumRegularSections = Asm.size();
+ DenseMap<const MCSection*, uint32_t> SectionIndexMap;
unsigned Index = 1;
for (MCAssembler::iterator it = Asm.begin(),
ie = Asm.end(); it != ie; ++it, ++Index)
StringMap<uint64_t> StringIndexMap;
StringTable += '\x00';
- // Add the data for local symbols.
+ // 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();
- // Ignore non-linker visible symbols.
- if (!Asm.isSymbolLinkerVisible(Symbol))
+ if (!isInSymtab(Asm, *it, UsedInReloc.count(&Symbol)))
continue;
- if (it->isExternal() || Symbol.isUndefined())
- continue;
-
- uint64_t &Entry = StringIndexMap[Symbol.getName()];
- if (!Entry) {
- Entry = StringTable.size();
- StringTable += Symbol.getName();
- StringTable += '\x00';
- }
-
ELFSymbolData MSD;
MSD.SymbolData = it;
- MSD.StringIndex = Entry;
-
- if (Symbol.isAbsolute()) {
- MSD.SectionIndex = ELF::SHN_ABS;
- LocalSymbolData.push_back(MSD);
- } else {
- MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
- assert(MSD.SectionIndex && "Invalid section index!");
- LocalSymbolData.push_back(MSD);
- }
- }
-
- // Now add non-local symbols.
- for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
- ie = Asm.symbol_end(); it != ie; ++it) {
- const MCSymbol &Symbol = it->getSymbol();
-
- // Ignore non-linker visible symbols.
- if (!Asm.isSymbolLinkerVisible(Symbol) && !Symbol.isUndefined())
- continue;
-
- if (!it->isExternal() && !Symbol.isUndefined())
- continue;
-
- if (Symbol.isVariable())
- continue;
-
- uint64_t &Entry = StringIndexMap[Symbol.getName()];
- if (!Entry) {
- Entry = StringTable.size();
- StringTable += Symbol.getName();
- StringTable += '\x00';
- }
-
- ELFSymbolData MSD;
- MSD.SymbolData = it;
- MSD.StringIndex = Entry;
+ bool Local = isLocal(*it);
+ bool Add = false;
if (it->isCommon()) {
+ assert(!Local);
MSD.SectionIndex = ELF::SHN_COMMON;
- ExternalSymbolData.push_back(MSD);
+ Add = true;
+ } else if (Symbol.isAbsolute()) {
+ MSD.SectionIndex = ELF::SHN_ABS;
+ Add = true;
+ } else if (Symbol.isVariable()) {
+ const MCSymbol &RefSymbol = AliasedSymbol(Symbol);
+ if (RefSymbol.isDefined()) {
+ MSD.SectionIndex = SectionIndexMap.lookup(&RefSymbol.getSection());
+ assert(MSD.SectionIndex && "Invalid section index!");
+ Add = true;
+ }
} else if (Symbol.isUndefined()) {
+ assert(!Local);
MSD.SectionIndex = ELF::SHN_UNDEF;
// FIXME: Undefined symbols are global, but this is the first place we
// are able to set it.
if (GetBinding(*it) == ELF::STB_LOCAL)
SetBinding(*it, ELF::STB_GLOBAL);
- UndefinedSymbolData.push_back(MSD);
- } else if (Symbol.isAbsolute()) {
- MSD.SectionIndex = ELF::SHN_ABS;
- ExternalSymbolData.push_back(MSD);
+ Add = true;
} else {
MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
assert(MSD.SectionIndex && "Invalid section index!");
- ExternalSymbolData.push_back(MSD);
+ Add = true;
+ }
+
+ if (Add) {
+ uint64_t &Entry = StringIndexMap[Symbol.getName()];
+ if (!Entry) {
+ Entry = StringTable.size();
+ StringTable += Symbol.getName();
+ 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);
}
}
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) {
char buf[8];
String64(buf, entry.r_offset);
F->getContents() += StringRef(buf, 8);
- String64(buf, entry.r_info);
+ struct ELF::Elf64_Rela ERE64;
+ ERE64.setSymbolAndType(entry.Index, entry.Type);
+ String64(buf, ERE64.r_info);
F->getContents() += StringRef(buf, 8);
if (HasRelocationAddend) {
String32(buf, entry.r_offset);
F->getContents() += StringRef(buf, 4);
- String32(buf, entry.r_info);
+ struct ELF::Elf32_Rela ERE32;
+ ERE32.setSymbolAndType(entry.Index, entry.Type);
+ String32(buf, ERE32.r_info);
F->getContents() += StringRef(buf, 4);
if (HasRelocationAddend) {
return !SectionB && BaseSection == SectionA;
}
-void ELFObjectWriterImpl::WriteObject(const MCAssembler &Asm,
+void ELFObjectWriterImpl::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
+ // Compute symbol table information.
+ ComputeSymbolTable(Asm);
+
CreateMetadataSections(const_cast<MCAssembler&>(Asm),
const_cast<MCAsmLayout&>(Layout));
// ... then all of the sections ...
DenseMap<const MCSection*, uint64_t> SectionOffsetMap;
- DenseMap<const MCSection*, uint8_t> SectionIndexMap;
+ DenseMap<const MCSection*, uint32_t> SectionIndexMap;
unsigned Index = 1;
for (MCAssembler::const_iterator it = Asm.begin(),
IsPCRel, DF);
}
-void ELFObjectWriter::WriteObject(const MCAssembler &Asm,
+void ELFObjectWriter::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
((ELFObjectWriterImpl*) Impl)->WriteObject(Asm, Layout);
}
projects / oota-llvm.git / blobdiff