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llvm-mirror/lib/MC/WinCOFFObjectWriter.cpp
Rafael Espindola 8dad37785c Sorry for such a large commit. The summary is that only MachO cares about the 
actuall addresses in a .o file, so it is better to let the MachO writer compute
it.

This is good for two reasons. First, areas that shouldn't care about
addresses now don't have access to it. Second, the layout of each section
is independent. I should use this in a subsequent commit to speed it up.

Most of the patch is just removing the section address computation. The two
interesting parts are the change on how we handle padding in the end
of sections and how MachO can get the address of a-b when a and b are in
different sections.

Since now the expression evaluation normally doesn't know the section address,
it will think that a-b needs relocation and let the MachO writer know. Once
it has computed the section addresses, it calls back the expression evaluation
with the section addresses to resolve these expressions.

The remaining problem is the handling of padding. Currently it will create
a special alignment fragment at the end. Since that fragment doesn't update
the alignment of the section, it needs the real address to be computed.

Since now the layout will not compute a-b with a and b in different sections,
the only effect that the special alignment fragment has is update the
address size of the section. This can also be done by the MachO writer.

llvm-svn: 121076
2010-12-07 00:27:36 +00:00

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//===-- llvm/MC/WinCOFFObjectWriter.cpp -------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains an implementation of a Win32 COFF object file writer.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "WinCOFFObjectWriter"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TimeValue.h"
#include "../Target/X86/X86FixupKinds.h"
#include <cstdio>
using namespace llvm;
namespace {
typedef llvm::SmallString<COFF::NameSize> name;
enum AuxiliaryType {
ATFunctionDefinition,
ATbfAndefSymbol,
ATWeakExternal,
ATFile,
ATSectionDefinition
};
struct AuxSymbol {
AuxiliaryType AuxType;
COFF::Auxiliary Aux;
};
class COFFSymbol;
class COFFSection;
class COFFSymbol {
public:
COFF::symbol Data;
typedef llvm::SmallVector<AuxSymbol, 1> AuxiliarySymbols;
name Name;
int Index;
AuxiliarySymbols Aux;
COFFSymbol *Other;
COFFSection *Section;
int Relocations;
MCSymbolData const *MCData;
COFFSymbol(llvm::StringRef name);
size_t size() const;
void set_name_offset(uint32_t Offset);
bool should_keep() const;
};
// This class contains staging data for a COFF relocation entry.
struct COFFRelocation {
COFF::relocation Data;
COFFSymbol *Symb;
COFFRelocation() : Symb(NULL) {}
static size_t size() { return COFF::RelocationSize; }
};
typedef std::vector<COFFRelocation> relocations;
class COFFSection {
public:
COFF::section Header;
std::string Name;
int Number;
MCSectionData const *MCData;
COFFSymbol *Symbol;
relocations Relocations;
COFFSection(llvm::StringRef name);
static size_t size();
};
// This class holds the COFF string table.
class StringTable {
typedef llvm::StringMap<size_t> map;
map Map;
void update_length();
public:
std::vector<char> Data;
StringTable();
size_t size() const;
size_t insert(llvm::StringRef String);
};
class WinCOFFObjectWriter : public MCObjectWriter {
public:
typedef std::vector<COFFSymbol*> symbols;
typedef std::vector<COFFSection*> sections;
typedef DenseMap<MCSymbol const *, COFFSymbol *> symbol_map;
typedef DenseMap<MCSection const *, COFFSection *> section_map;
// Root level file contents.
bool Is64Bit;
COFF::header Header;
sections Sections;
symbols Symbols;
StringTable Strings;
// Maps used during object file creation.
section_map SectionMap;
symbol_map SymbolMap;
WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit);
~WinCOFFObjectWriter();
COFFSymbol *createSymbol(StringRef Name);
COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
COFFSection *createSection(StringRef Name);
template <typename object_t, typename list_t>
object_t *createCOFFEntity(llvm::StringRef Name, list_t &List);
void DefineSection(MCSectionData const &SectionData);
void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler);
void MakeSymbolReal(COFFSymbol &S, size_t Index);
void MakeSectionReal(COFFSection &S, size_t Number);
bool ExportSection(COFFSection const *S);
bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
bool IsPhysicalSection(COFFSection *S);
// Entity writing methods.
void WriteFileHeader(const COFF::header &Header);
void WriteSymbol(const COFFSymbol *S);
void WriteAuxiliarySymbols(const COFFSymbol::AuxiliarySymbols &S);
void WriteSectionHeader(const COFF::section &S);
void WriteRelocation(const COFF::relocation &R);
// MCObjectWriter interface implementation.
void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
void RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup,
MCValue Target,
uint64_t &FixedValue);
virtual bool IsFixupFullyResolved(const MCAssembler &Asm,
const MCValue Target,
bool IsPCRel,
const MCFragment *DF) const;
void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout);
};
}
static inline void write_uint32_le(void *Data, uint32_t const &Value) {
uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
Ptr[0] = (Value & 0x000000FF) >> 0;
Ptr[1] = (Value & 0x0000FF00) >> 8;
Ptr[2] = (Value & 0x00FF0000) >> 16;
Ptr[3] = (Value & 0xFF000000) >> 24;
}
static inline void write_uint16_le(void *Data, uint16_t const &Value) {
uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
Ptr[0] = (Value & 0x00FF) >> 0;
Ptr[1] = (Value & 0xFF00) >> 8;
}
static inline void write_uint8_le(void *Data, uint8_t const &Value) {
uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
Ptr[0] = (Value & 0xFF) >> 0;
}
//------------------------------------------------------------------------------
// Symbol class implementation
COFFSymbol::COFFSymbol(llvm::StringRef name)
: Name(name.begin(), name.end())
, Other(NULL)
, Section(NULL)
, Relocations(0)
, MCData(NULL) {
memset(&Data, 0, sizeof(Data));
}
size_t COFFSymbol::size() const {
return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
}
// In the case that the name does not fit within 8 bytes, the offset
// into the string table is stored in the last 4 bytes instead, leaving
// the first 4 bytes as 0.
void COFFSymbol::set_name_offset(uint32_t Offset) {
write_uint32_le(Data.Name + 0, 0);
write_uint32_le(Data.Name + 4, Offset);
}
/// logic to decide if the symbol should be reported in the symbol table
bool COFFSymbol::should_keep() const {
// no section means its external, keep it
if (Section == NULL)
return true;
// if it has relocations pointing at it, keep it
if (Relocations > 0) {
assert(Section->Number != -1 && "Sections with relocations must be real!");
return true;
}
// if the section its in is being droped, drop it
if (Section->Number == -1)
return false;
// if it is the section symbol, keep it
if (Section->Symbol == this)
return true;
// if its temporary, drop it
if (MCData && MCData->getSymbol().isTemporary())
return false;
// otherwise, keep it
return true;
}
//------------------------------------------------------------------------------
// Section class implementation
COFFSection::COFFSection(llvm::StringRef name)
: Name(name)
, MCData(NULL)
, Symbol(NULL) {
memset(&Header, 0, sizeof(Header));
}
size_t COFFSection::size() {
return COFF::SectionSize;
}
//------------------------------------------------------------------------------
// StringTable class implementation
/// Write the length of the string table into Data.
/// The length of the string table includes uint32 length header.
void StringTable::update_length() {
write_uint32_le(&Data.front(), Data.size());
}
StringTable::StringTable() {
// The string table data begins with the length of the entire string table
// including the length header. Allocate space for this header.
Data.resize(4);
}
size_t StringTable::size() const {
return Data.size();
}
/// Add String to the table iff it is not already there.
/// @returns the index into the string table where the string is now located.
size_t StringTable::insert(llvm::StringRef String) {
map::iterator i = Map.find(String);
if (i != Map.end())
return i->second;
size_t Offset = Data.size();
// Insert string data into string table.
Data.insert(Data.end(), String.begin(), String.end());
Data.push_back('\0');
// Put a reference to it in the map.
Map[String] = Offset;
// Update the internal length field.
update_length();
return Offset;
}
//------------------------------------------------------------------------------
// WinCOFFObjectWriter class implementation
WinCOFFObjectWriter::WinCOFFObjectWriter(raw_ostream &OS, bool is64Bit)
: MCObjectWriter(OS, true)
, Is64Bit(is64Bit) {
memset(&Header, 0, sizeof(Header));
Is64Bit ? Header.Machine = COFF::IMAGE_FILE_MACHINE_AMD64
: Header.Machine = COFF::IMAGE_FILE_MACHINE_I386;
}
WinCOFFObjectWriter::~WinCOFFObjectWriter() {
for (symbols::iterator I = Symbols.begin(), E = Symbols.end(); I != E; ++I)
delete *I;
for (sections::iterator I = Sections.begin(), E = Sections.end(); I != E; ++I)
delete *I;
}
COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
return createCOFFEntity<COFFSymbol>(Name, Symbols);
}
COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
symbol_map::iterator i = SymbolMap.find(Symbol);
if (i != SymbolMap.end())
return i->second;
COFFSymbol *RetSymbol
= createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
SymbolMap[Symbol] = RetSymbol;
return RetSymbol;
}
COFFSection *WinCOFFObjectWriter::createSection(llvm::StringRef Name) {
return createCOFFEntity<COFFSection>(Name, Sections);
}
/// A template used to lookup or create a symbol/section, and initialize it if
/// needed.
template <typename object_t, typename list_t>
object_t *WinCOFFObjectWriter::createCOFFEntity(llvm::StringRef Name,
list_t &List) {
object_t *Object = new object_t(Name);
List.push_back(Object);
return Object;
}
/// This function takes a section data object from the assembler
/// and creates the associated COFF section staging object.
void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
assert(SectionData.getSection().getVariant() == MCSection::SV_COFF
&& "Got non COFF section in the COFF backend!");
// FIXME: Not sure how to verify this (at least in a debug build).
MCSectionCOFF const &Sec =
static_cast<MCSectionCOFF const &>(SectionData.getSection());
COFFSection *coff_section = createSection(Sec.getSectionName());
COFFSymbol *coff_symbol = createSymbol(Sec.getSectionName());
coff_section->Symbol = coff_symbol;
coff_symbol->Section = coff_section;
coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_STATIC;
// In this case the auxiliary symbol is a Section Definition.
coff_symbol->Aux.resize(1);
memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
coff_symbol->Aux[0].AuxType = ATSectionDefinition;
coff_symbol->Aux[0].Aux.SectionDefinition.Selection = Sec.getSelection();
coff_section->Header.Characteristics = Sec.getCharacteristics();
uint32_t &Characteristics = coff_section->Header.Characteristics;
switch (SectionData.getAlignment()) {
case 1: Characteristics |= COFF::IMAGE_SCN_ALIGN_1BYTES; break;
case 2: Characteristics |= COFF::IMAGE_SCN_ALIGN_2BYTES; break;
case 4: Characteristics |= COFF::IMAGE_SCN_ALIGN_4BYTES; break;
case 8: Characteristics |= COFF::IMAGE_SCN_ALIGN_8BYTES; break;
case 16: Characteristics |= COFF::IMAGE_SCN_ALIGN_16BYTES; break;
case 32: Characteristics |= COFF::IMAGE_SCN_ALIGN_32BYTES; break;
case 64: Characteristics |= COFF::IMAGE_SCN_ALIGN_64BYTES; break;
case 128: Characteristics |= COFF::IMAGE_SCN_ALIGN_128BYTES; break;
case 256: Characteristics |= COFF::IMAGE_SCN_ALIGN_256BYTES; break;
case 512: Characteristics |= COFF::IMAGE_SCN_ALIGN_512BYTES; break;
case 1024: Characteristics |= COFF::IMAGE_SCN_ALIGN_1024BYTES; break;
case 2048: Characteristics |= COFF::IMAGE_SCN_ALIGN_2048BYTES; break;
case 4096: Characteristics |= COFF::IMAGE_SCN_ALIGN_4096BYTES; break;
case 8192: Characteristics |= COFF::IMAGE_SCN_ALIGN_8192BYTES; break;
default:
llvm_unreachable("unsupported section alignment");
}
// Bind internal COFF section to MC section.
coff_section->MCData = &SectionData;
SectionMap[&SectionData.getSection()] = coff_section;
}
/// This function takes a section data object from the assembler
/// and creates the associated COFF symbol staging object.
void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
MCAssembler &Assembler) {
COFFSymbol *coff_symbol = GetOrCreateCOFFSymbol(&SymbolData.getSymbol());
coff_symbol->Data.Type = (SymbolData.getFlags() & 0x0000FFFF) >> 0;
coff_symbol->Data.StorageClass = (SymbolData.getFlags() & 0x00FF0000) >> 16;
if (SymbolData.getFlags() & COFF::SF_WeakExternal) {
coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
if (SymbolData.getSymbol().isVariable()) {
coff_symbol->Data.StorageClass = COFF::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
const MCExpr *Value = SymbolData.getSymbol().getVariableValue();
// FIXME: This assert message isn't very good.
assert(Value->getKind() == MCExpr::SymbolRef &&
"Value must be a SymbolRef!");
const MCSymbolRefExpr *SymbolRef =
static_cast<const MCSymbolRefExpr *>(Value);
coff_symbol->Other = GetOrCreateCOFFSymbol(&SymbolRef->getSymbol());
} else {
std::string WeakName = std::string(".weak.")
+ SymbolData.getSymbol().getName().str()
+ ".default";
COFFSymbol *WeakDefault = createSymbol(WeakName);
WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
WeakDefault->Data.StorageClass = COFF::IMAGE_SYM_CLASS_EXTERNAL;
WeakDefault->Data.Type = 0;
WeakDefault->Data.Value = 0;
coff_symbol->Other = WeakDefault;
}
// Setup the Weak External auxiliary symbol.
coff_symbol->Aux.resize(1);
memset(&coff_symbol->Aux[0], 0, sizeof(coff_symbol->Aux[0]));
coff_symbol->Aux[0].AuxType = ATWeakExternal;
coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = 0;
coff_symbol->Aux[0].Aux.WeakExternal.Characteristics =
COFF::IMAGE_WEAK_EXTERN_SEARCH_LIBRARY;
}
// If no storage class was specified in the streamer, define it here.
if (coff_symbol->Data.StorageClass == 0) {
bool external = SymbolData.isExternal() || (SymbolData.Fragment == NULL);
coff_symbol->Data.StorageClass =
external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
}
if (SymbolData.Fragment != NULL)
coff_symbol->Section =
SectionMap[&SymbolData.Fragment->getParent()->getSection()];
// Bind internal COFF symbol to MC symbol.
coff_symbol->MCData = &SymbolData;
SymbolMap[&SymbolData.getSymbol()] = coff_symbol;
}
/// making a section real involves assigned it a number and putting
/// name into the string table if needed
void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
if (S.Name.size() > COFF::NameSize) {
size_t StringTableEntry = Strings.insert(S.Name.c_str());
// FIXME: Why is this number 999999? This number is never mentioned in the
// spec. I'm assuming this is due to the printed value needing to fit into
// the S.Header.Name field. In which case why not 9999999 (7 9's instead of
// 6)? The spec does not state if this entry should be null terminated in
// this case, and thus this seems to be the best way to do it. I think I
// just solved my own FIXME...
if (StringTableEntry > 999999)
report_fatal_error("COFF string table is greater than 999999 bytes.");
std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
} else
std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
S.Number = Number;
S.Symbol->Data.SectionNumber = S.Number;
S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
}
void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
if (S.Name.size() > COFF::NameSize) {
size_t StringTableEntry = Strings.insert(S.Name.c_str());
S.set_name_offset(StringTableEntry);
} else
std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
S.Index = Index;
}
bool WinCOFFObjectWriter::ExportSection(COFFSection const *S) {
return !S->MCData->getFragmentList().empty();
}
bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
MCAssembler &Asm) {
// This doesn't seem to be right. Strings referred to from the .data section
// need symbols so they can be linked to code in the .text section right?
// return Asm.isSymbolLinkerVisible (&SymbolData);
// For now, all non-variable symbols are exported,
// the linker will sort the rest out for us.
return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
}
bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
return (S->Header.Characteristics
& COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) == 0;
}
//------------------------------------------------------------------------------
// entity writing methods
void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
WriteLE16(Header.Machine);
WriteLE16(Header.NumberOfSections);
WriteLE32(Header.TimeDateStamp);
WriteLE32(Header.PointerToSymbolTable);
WriteLE32(Header.NumberOfSymbols);
WriteLE16(Header.SizeOfOptionalHeader);
WriteLE16(Header.Characteristics);
}
void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol *S) {
WriteBytes(StringRef(S->Data.Name, COFF::NameSize));
WriteLE32(S->Data.Value);
WriteLE16(S->Data.SectionNumber);
WriteLE16(S->Data.Type);
Write8(S->Data.StorageClass);
Write8(S->Data.NumberOfAuxSymbols);
WriteAuxiliarySymbols(S->Aux);
}
void WinCOFFObjectWriter::WriteAuxiliarySymbols(
const COFFSymbol::AuxiliarySymbols &S) {
for(COFFSymbol::AuxiliarySymbols::const_iterator i = S.begin(), e = S.end();
i != e; ++i) {
switch(i->AuxType) {
case ATFunctionDefinition:
WriteLE32(i->Aux.FunctionDefinition.TagIndex);
WriteLE32(i->Aux.FunctionDefinition.TotalSize);
WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
break;
case ATbfAndefSymbol:
WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
WriteLE16(i->Aux.bfAndefSymbol.Linenumber);
WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
break;
case ATWeakExternal:
WriteLE32(i->Aux.WeakExternal.TagIndex);
WriteLE32(i->Aux.WeakExternal.Characteristics);
WriteZeros(sizeof(i->Aux.WeakExternal.unused));
break;
case ATFile:
WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
sizeof(i->Aux.File.FileName)));
break;
case ATSectionDefinition:
WriteLE32(i->Aux.SectionDefinition.Length);
WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
WriteLE32(i->Aux.SectionDefinition.CheckSum);
WriteLE16(i->Aux.SectionDefinition.Number);
Write8(i->Aux.SectionDefinition.Selection);
WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
break;
}
}
}
void WinCOFFObjectWriter::WriteSectionHeader(const COFF::section &S) {
WriteBytes(StringRef(S.Name, COFF::NameSize));
WriteLE32(S.VirtualSize);
WriteLE32(S.VirtualAddress);
WriteLE32(S.SizeOfRawData);
WriteLE32(S.PointerToRawData);
WriteLE32(S.PointerToRelocations);
WriteLE32(S.PointerToLineNumbers);
WriteLE16(S.NumberOfRelocations);
WriteLE16(S.NumberOfLineNumbers);
WriteLE32(S.Characteristics);
}
void WinCOFFObjectWriter::WriteRelocation(const COFF::relocation &R) {
WriteLE32(R.VirtualAddress);
WriteLE32(R.SymbolTableIndex);
WriteLE16(R.Type);
}
////////////////////////////////////////////////////////////////////////////////
// MCObjectWriter interface implementations
void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) {
// "Define" each section & symbol. This creates section & symbol
// entries in the staging area.
for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
DefineSection(*i);
for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
e = Asm.symbol_end(); i != e; i++) {
if (ExportSymbol(*i, Asm))
DefineSymbol(*i, Asm);
}
}
void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup,
MCValue Target,
uint64_t &FixedValue) {
assert(Target.getSymA() != NULL && "Relocation must reference a symbol!");
const MCSymbol *A = &Target.getSymA()->getSymbol();
MCSymbolData &A_SD = Asm.getSymbolData(*A);
MCSectionData const *SectionData = Fragment->getParent();
// Mark this symbol as requiring an entry in the symbol table.
assert(SectionMap.find(&SectionData->getSection()) != SectionMap.end() &&
"Section must already have been defined in ExecutePostLayoutBinding!");
assert(SymbolMap.find(&A_SD.getSymbol()) != SymbolMap.end() &&
"Symbol must already have been defined in ExecutePostLayoutBinding!");
COFFSection *coff_section = SectionMap[&SectionData->getSection()];
COFFSymbol *coff_symbol = SymbolMap[&A_SD.getSymbol()];
if (Target.getSymB()) {
if (&Target.getSymA()->getSymbol().getSection()
!= &Target.getSymB()->getSymbol().getSection()) {
llvm_unreachable("Symbol relative relocations are only allowed between "
"symbols in the same section");
}
const MCSymbol *B = &Target.getSymB()->getSymbol();
MCSymbolData &B_SD = Asm.getSymbolData(*B);
FixedValue = Layout.getSymbolOffset(&A_SD) - Layout.getSymbolOffset(&B_SD);
// In the case where we have SymbA and SymB, we just need to store the delta
// between the two symbols. Update FixedValue to account for the delta, and
// skip recording the relocation.
return;
} else {
FixedValue = Target.getConstant();
}
COFFRelocation Reloc;
Reloc.Data.SymbolTableIndex = 0;
Reloc.Data.VirtualAddress = Layout.getFragmentOffset(Fragment);
// Turn relocations for temporary symbols into section relocations.
if (coff_symbol->MCData->getSymbol().isTemporary()) {
Reloc.Symb = coff_symbol->Section->Symbol;
FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
+ coff_symbol->MCData->getOffset();
} else
Reloc.Symb = coff_symbol;
++Reloc.Symb->Relocations;
Reloc.Data.VirtualAddress += Fixup.getOffset();
switch ((unsigned)Fixup.getKind()) {
case FK_PCRel_4:
case X86::reloc_riprel_4byte:
case X86::reloc_riprel_4byte_movq_load:
Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_REL32
: COFF::IMAGE_REL_I386_REL32;
// FIXME: Can anyone explain what this does other than adjust for the size
// of the offset?
FixedValue += 4;
break;
case FK_Data_4:
case X86::reloc_signed_4byte:
Reloc.Data.Type = Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32
: COFF::IMAGE_REL_I386_DIR32;
break;
case FK_Data_8:
if (Is64Bit)
Reloc.Data.Type = COFF::IMAGE_REL_AMD64_ADDR64;
else
llvm_unreachable("unsupported relocation type");
break;
default:
llvm_unreachable("unsupported relocation type");
}
coff_section->Relocations.push_back(Reloc);
}
bool WinCOFFObjectWriter::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();
SectionA = &SymbolA->getSection();
}
const MCSection *SectionB = 0;
if (const MCSymbolRefExpr *B = Target.getSymB()) {
SectionB = &B->getSymbol().getSection();
}
if (!BaseSection)
return SectionA == SectionB;
return !SectionB && BaseSection == SectionA;
}
void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
// Assign symbol and section indexes and offsets.
Header.NumberOfSections = 0;
for (sections::iterator i = Sections.begin(),
e = Sections.end(); i != e; i++) {
if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
MakeSectionReal(**i, ++Header.NumberOfSections);
} else {
(*i)->Number = -1;
}
}
Header.NumberOfSymbols = 0;
for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
COFFSymbol *coff_symbol = *i;
MCSymbolData const *SymbolData = coff_symbol->MCData;
// Update section number & offset for symbols that have them.
if ((SymbolData != NULL) && (SymbolData->Fragment != NULL)) {
assert(coff_symbol->Section != NULL);
coff_symbol->Data.SectionNumber = coff_symbol->Section->Number;
coff_symbol->Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
+ SymbolData->Offset;
}
if (coff_symbol->should_keep()) {
MakeSymbolReal(*coff_symbol, Header.NumberOfSymbols++);
// Update auxiliary symbol info.
coff_symbol->Data.NumberOfAuxSymbols = coff_symbol->Aux.size();
Header.NumberOfSymbols += coff_symbol->Data.NumberOfAuxSymbols;
} else
coff_symbol->Index = -1;
}
// Fixup weak external references.
for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
COFFSymbol *coff_symbol = *i;
if (coff_symbol->Other != NULL) {
assert(coff_symbol->Index != -1);
assert(coff_symbol->Aux.size() == 1 &&
"Symbol must contain one aux symbol!");
assert(coff_symbol->Aux[0].AuxType == ATWeakExternal &&
"Symbol's aux symbol must be a Weak External!");
coff_symbol->Aux[0].Aux.WeakExternal.TagIndex = coff_symbol->Other->Index;
}
}
// Assign file offsets to COFF object file structures.
unsigned offset = 0;
offset += COFF::HeaderSize;
offset += COFF::SectionSize * Header.NumberOfSections;
for (MCAssembler::const_iterator i = Asm.begin(),
e = Asm.end();
i != e; i++) {
COFFSection *Sec = SectionMap[&i->getSection()];
if (Sec->Number == -1)
continue;
Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
if (IsPhysicalSection(Sec)) {
Sec->Header.PointerToRawData = offset;
offset += Sec->Header.SizeOfRawData;
}
if (Sec->Relocations.size() > 0) {
Sec->Header.NumberOfRelocations = Sec->Relocations.size();
Sec->Header.PointerToRelocations = offset;
offset += COFF::RelocationSize * Sec->Relocations.size();
for (relocations::iterator cr = Sec->Relocations.begin(),
er = Sec->Relocations.end();
cr != er; ++cr) {
assert((*cr).Symb->Index != -1);
(*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
}
}
assert(Sec->Symbol->Aux.size() == 1
&& "Section's symbol must have one aux!");
AuxSymbol &Aux = Sec->Symbol->Aux[0];
assert(Aux.AuxType == ATSectionDefinition &&
"Section's symbol's aux symbol must be a Section Definition!");
Aux.Aux.SectionDefinition.Length = Sec->Header.SizeOfRawData;
Aux.Aux.SectionDefinition.NumberOfRelocations =
Sec->Header.NumberOfRelocations;
Aux.Aux.SectionDefinition.NumberOfLinenumbers =
Sec->Header.NumberOfLineNumbers;
}
Header.PointerToSymbolTable = offset;
Header.TimeDateStamp = sys::TimeValue::now().toEpochTime();
// Write it all to disk...
WriteFileHeader(Header);
{
sections::iterator i, ie;
MCAssembler::const_iterator j, je;
for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
if ((*i)->Number != -1)
WriteSectionHeader((*i)->Header);
for (i = Sections.begin(), ie = Sections.end(),
j = Asm.begin(), je = Asm.end();
(i != ie) && (j != je); ++i, ++j) {
if ((*i)->Number == -1)
continue;
if ((*i)->Header.PointerToRawData != 0) {
assert(OS.tell() == (*i)->Header.PointerToRawData &&
"Section::PointerToRawData is insane!");
Asm.WriteSectionData(j, Layout, this);
}
if ((*i)->Relocations.size() > 0) {
assert(OS.tell() == (*i)->Header.PointerToRelocations &&
"Section::PointerToRelocations is insane!");
for (relocations::const_iterator k = (*i)->Relocations.begin(),
ke = (*i)->Relocations.end();
k != ke; k++) {
WriteRelocation(k->Data);
}
} else
assert((*i)->Header.PointerToRelocations == 0 &&
"Section::PointerToRelocations is insane!");
}
}
assert(OS.tell() == Header.PointerToSymbolTable &&
"Header::PointerToSymbolTable is insane!");
for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
if ((*i)->Index != -1)
WriteSymbol(*i);
OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
}
//------------------------------------------------------------------------------
// WinCOFFObjectWriter factory function
namespace llvm {
MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit) {
return new WinCOFFObjectWriter(OS, is64Bit);
}
}
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