//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "assembler"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCSectionMachO.h"
-#include "llvm/Support/DataTypes.h"
-#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachOWriterInfo.h"
-
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include <vector>
using namespace llvm;
-namespace {
+class MachObjectWriter;
+
+STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
+
+// FIXME FIXME FIXME: There are number of places in this file where we convert
+// what is a 64-bit assembler value used for computation into a value in the
+// object file, which may truncate it. We should detect that truncation where
+// invalid and report errors back.
+
+static void WriteFileData(raw_ostream &OS, const MCSectionData &SD,
+ MachObjectWriter &MOW);
+
+/// isVirtualSection - Check if this is a section which does not actually exist
+/// in the object file.
+static bool isVirtualSection(const MCSection &Section) {
+ // FIXME: Lame.
+ const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section);
+ unsigned Type = SMO.getTypeAndAttributes() & MCSectionMachO::SECTION_TYPE;
+ return (Type == MCSectionMachO::S_ZEROFILL);
+}
class MachObjectWriter {
// See <mach-o/loader.h>.
static const unsigned Header64Size = 32;
static const unsigned SegmentLoadCommand32Size = 56;
static const unsigned Section32Size = 68;
+ static const unsigned SymtabLoadCommandSize = 24;
+ static const unsigned DysymtabLoadCommandSize = 80;
+ static const unsigned Nlist32Size = 12;
+ static const unsigned RelocationInfoSize = 8;
enum HeaderFileType {
HFT_Object = 0x1
};
+ enum HeaderFlags {
+ HF_SubsectionsViaSymbols = 0x2000
+ };
+
enum LoadCommandType {
- LCT_Segment = 0x1
+ LCT_Segment = 0x1,
+ LCT_Symtab = 0x2,
+ LCT_Dysymtab = 0xb
+ };
+
+ // See <mach-o/nlist.h>.
+ enum SymbolTypeType {
+ STT_Undefined = 0x00,
+ STT_Absolute = 0x02,
+ STT_Section = 0x0e
+ };
+
+ enum SymbolTypeFlags {
+ // If any of these bits are set, then the entry is a stab entry number (see
+ // <mach-o/stab.h>. Otherwise the other masks apply.
+ STF_StabsEntryMask = 0xe0,
+
+ STF_TypeMask = 0x0e,
+ STF_External = 0x01,
+ STF_PrivateExtern = 0x10
+ };
+
+ /// IndirectSymbolFlags - Flags for encoding special values in the indirect
+ /// symbol entry.
+ enum IndirectSymbolFlags {
+ ISF_Local = 0x80000000,
+ ISF_Absolute = 0x40000000
+ };
+
+ /// RelocationFlags - Special flags for addresses.
+ enum RelocationFlags {
+ RF_Scattered = 0x80000000
+ };
+
+ enum RelocationInfoType {
+ RIT_Vanilla = 0,
+ RIT_Pair = 1,
+ RIT_Difference = 2,
+ RIT_PreboundLazyPointer = 3,
+ RIT_LocalDifference = 4
+ };
+
+ /// MachSymbolData - Helper struct for containing some precomputed information
+ /// on symbols.
+ struct MachSymbolData {
+ MCSymbolData *SymbolData;
+ uint64_t StringIndex;
+ uint8_t SectionIndex;
+
+ // Support lexicographic sorting.
+ bool operator<(const MachSymbolData &RHS) const {
+ const std::string &Name = SymbolData->getSymbol().getName();
+ return Name < RHS.SymbolData->getSymbol().getName();
+ }
};
raw_ostream &OS;
/// @name Helper Methods
/// @{
+ void Write8(uint8_t Value) {
+ OS << char(Value);
+ }
+
+ void Write16(uint16_t Value) {
+ if (IsLSB) {
+ Write8(uint8_t(Value >> 0));
+ Write8(uint8_t(Value >> 8));
+ } else {
+ Write8(uint8_t(Value >> 8));
+ Write8(uint8_t(Value >> 0));
+ }
+ }
+
void Write32(uint32_t Value) {
if (IsLSB) {
- OS << char(Value >> 0);
- OS << char(Value >> 8);
- OS << char(Value >> 16);
- OS << char(Value >> 24);
+ Write16(uint16_t(Value >> 0));
+ Write16(uint16_t(Value >> 16));
} else {
- OS << char(Value >> 24);
- OS << char(Value >> 16);
- OS << char(Value >> 8);
- OS << char(Value >> 0);
+ Write16(uint16_t(Value >> 16));
+ Write16(uint16_t(Value >> 0));
+ }
+ }
+
+ void Write64(uint64_t Value) {
+ if (IsLSB) {
+ Write32(uint32_t(Value >> 0));
+ Write32(uint32_t(Value >> 32));
+ } else {
+ Write32(uint32_t(Value >> 32));
+ Write32(uint32_t(Value >> 0));
}
}
/// @}
- static unsigned getPrologSize32(unsigned NumSections) {
- return Header32Size + SegmentLoadCommand32Size +
- NumSections * Section32Size;
- }
+ void WriteHeader32(unsigned NumLoadCommands, unsigned LoadCommandsSize,
+ bool SubsectionsViaSymbols) {
+ uint32_t Flags = 0;
+
+ if (SubsectionsViaSymbols)
+ Flags |= HF_SubsectionsViaSymbols;
- void WriteHeader32(unsigned NumSections) {
// struct mach_header (28 bytes)
uint64_t Start = OS.tell();
// FIXME: Support cputype.
Write32(TargetMachOWriterInfo::HDR_CPU_TYPE_I386);
-
// FIXME: Support cpusubtype.
Write32(TargetMachOWriterInfo::HDR_CPU_SUBTYPE_I386_ALL);
-
Write32(HFT_Object);
-
- // Object files have a single load command, the segment.
- Write32(1);
- Write32(SegmentLoadCommand32Size + NumSections * Section32Size);
- Write32(0); // Flags
+ Write32(NumLoadCommands); // Object files have a single load command, the
+ // segment.
+ Write32(LoadCommandsSize);
+ Write32(Flags);
assert(OS.tell() - Start == Header32Size);
}
- void WriteLoadCommandHeader(uint32_t Cmd, uint32_t CmdSize) {
- assert((CmdSize & 0x3) == 0 && "Invalid size!");
-
- Write32(Cmd);
- Write32(CmdSize);
- }
-
- void WriteSegmentLoadCommand32(unsigned NumSections) {
+ /// WriteSegmentLoadCommand32 - Write a 32-bit segment load command.
+ ///
+ /// \arg NumSections - The number of sections in this segment.
+ /// \arg SectionDataSize - The total size of the sections.
+ void WriteSegmentLoadCommand32(unsigned NumSections,
+ uint64_t VMSize,
+ uint64_t SectionDataStartOffset,
+ uint64_t SectionDataSize) {
// struct segment_command (56 bytes)
uint64_t Start = OS.tell();
WriteString("", 16);
Write32(0); // vmaddr
- Write32(0); // vmsize
- Write32(Header32Size + SegmentLoadCommand32Size +
- NumSections * Section32Size); // file offset
- Write32(0); // file size
+ Write32(VMSize); // vmsize
+ Write32(SectionDataStartOffset); // file offset
+ Write32(SectionDataSize); // file size
Write32(0x7); // maxprot
Write32(0x7); // initprot
Write32(NumSections);
assert(OS.tell() - Start == SegmentLoadCommand32Size);
}
- void WriteSection32(const MCSectionData &SD) {
+ void WriteSection32(const MCSectionData &SD, uint64_t FileOffset,
+ uint64_t RelocationsStart, unsigned NumRelocations) {
+ // The offset is unused for virtual sections.
+ if (isVirtualSection(SD.getSection())) {
+ assert(SD.getFileSize() == 0 && "Invalid file size!");
+ FileOffset = 0;
+ }
+
// struct section (68 bytes)
uint64_t Start = OS.tell();
static_cast<const MCSectionMachO&>(SD.getSection());
WriteString(Section.getSectionName(), 16);
WriteString(Section.getSegmentName(), 16);
- Write32(0); // address
- Write32(SD.getFileSize()); // size
- Write32(SD.getFileOffset());
+ Write32(SD.getAddress()); // address
+ Write32(SD.getSize()); // size
+ Write32(FileOffset);
assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
Write32(Log2_32(SD.getAlignment()));
- Write32(0); // file offset of relocation entries
- Write32(0); // number of relocation entrions
+ Write32(NumRelocations ? RelocationsStart : 0);
+ Write32(NumRelocations);
Write32(Section.getTypeAndAttributes());
Write32(0); // reserved1
Write32(Section.getStubSize()); // reserved2
assert(OS.tell() - Start == Section32Size);
}
-};
-}
+ void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
+ uint32_t StringTableOffset,
+ uint32_t StringTableSize) {
+ // struct symtab_command (24 bytes)
+
+ 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) {
+ // struct dysymtab_command (80 bytes)
+
+ 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); // tocoff
+ Write32(0); // ntoc
+ Write32(0); // modtaboff
+ Write32(0); // nmodtab
+ Write32(0); // extrefsymoff
+ Write32(0); // nextrefsyms
+ Write32(IndirectSymbolOffset);
+ Write32(NumIndirectSymbols);
+ Write32(0); // extreloff
+ Write32(0); // nextrel
+ Write32(0); // locreloff
+ Write32(0); // nlocrel
+
+ assert(OS.tell() - Start == DysymtabLoadCommandSize);
+ }
+
+ void WriteNlist32(MachSymbolData &MSD) {
+ MCSymbolData &Data = *MSD.SymbolData;
+ MCSymbol &Symbol = Data.getSymbol();
+ uint8_t Type = 0;
+ uint16_t Flags = Data.getFlags();
+ uint32_t Address = 0;
+
+ // Set the N_TYPE bits. See <mach-o/nlist.h>.
+ //
+ // FIXME: Are the prebound or indirect fields possible here?
+ if (Symbol.isUndefined())
+ Type = STT_Undefined;
+ else if (Symbol.isAbsolute())
+ Type = STT_Absolute;
+ else
+ Type = STT_Section;
+
+ // FIXME: Set STAB bits.
+
+ if (Data.isPrivateExtern())
+ Type |= STF_PrivateExtern;
+
+ // Set external bit.
+ if (Data.isExternal() || Symbol.isUndefined())
+ Type |= STF_External;
+
+ // Compute the symbol address.
+ if (Symbol.isDefined()) {
+ if (Symbol.isAbsolute()) {
+ llvm_unreachable("FIXME: Not yet implemented!");
+ } else {
+ Address = Data.getFragment()->getAddress() + Data.getOffset();
+ }
+ } else if (Data.isCommon()) {
+ // Common symbols are encoded with the size in the address
+ // field, and their alignment in the flags.
+ Address = Data.getCommonSize();
+
+ // Common alignment is packed into the 'desc' bits.
+ if (unsigned Align = Data.getCommonAlignment()) {
+ unsigned Log2Size = Log2_32(Align);
+ assert((1U << Log2Size) == Align && "Invalid 'common' alignment!");
+ if (Log2Size > 15)
+ llvm_report_error("invalid 'common' alignment '" +
+ Twine(Align) + "'");
+ // FIXME: Keep this mask with the SymbolFlags enumeration.
+ Flags = (Flags & 0xF0FF) | (Log2Size << 8);
+ }
+ }
+
+ // struct nlist (12 bytes)
+
+ Write32(MSD.StringIndex);
+ Write8(Type);
+ Write8(MSD.SectionIndex);
+
+ // The Mach-O streamer uses the lowest 16-bits of the flags for the 'desc'
+ // value.
+ Write16(Flags);
+ Write32(Address);
+ }
+
+ struct MachRelocationEntry {
+ uint32_t Word0;
+ uint32_t Word1;
+ };
+ void ComputeScatteredRelocationInfo(MCAssembler &Asm,
+ MCSectionData::Fixup &Fixup,
+ DenseMap<const MCSymbol*,MCSymbolData*> &SymbolMap,
+ std::vector<MachRelocationEntry> &Relocs) {
+ uint32_t Address = Fixup.Fragment->getOffset() + Fixup.Offset;
+ unsigned IsPCRel = 0;
+ unsigned Type = RIT_Vanilla;
+
+ // See <reloc.h>.
+
+ const MCSymbol *A = Fixup.Value.getSymA();
+ MCSymbolData *SD = SymbolMap.lookup(A);
+ uint32_t Value = SD->getFragment()->getAddress() + SD->getOffset();
+ uint32_t Value2 = 0;
+
+ if (const MCSymbol *B = Fixup.Value.getSymB()) {
+ Type = RIT_LocalDifference;
+
+ MCSymbolData *SD = SymbolMap.lookup(B);
+ Value2 = SD->getFragment()->getAddress() + SD->getOffset();
+ }
+
+ unsigned Log2Size = Log2_32(Fixup.Size);
+ assert((1U << Log2Size) == Fixup.Size && "Invalid fixup size!");
+
+ // The value which goes in the fixup is current value of the expression.
+ Fixup.FixedValue = Value - Value2 + Fixup.Value.getConstant();
+
+ MachRelocationEntry MRE;
+ MRE.Word0 = ((Address << 0) |
+ (Type << 24) |
+ (Log2Size << 28) |
+ (IsPCRel << 30) |
+ RF_Scattered);
+ MRE.Word1 = Value;
+ Relocs.push_back(MRE);
+
+ if (Type == RIT_LocalDifference) {
+ Type = RIT_Pair;
+
+ MachRelocationEntry MRE;
+ MRE.Word0 = ((0 << 0) |
+ (Type << 24) |
+ (Log2Size << 28) |
+ (0 << 30) |
+ RF_Scattered);
+ MRE.Word1 = Value2;
+ Relocs.push_back(MRE);
+ }
+ }
+
+ void ComputeRelocationInfo(MCAssembler &Asm,
+ MCSectionData::Fixup &Fixup,
+ DenseMap<const MCSymbol*,MCSymbolData*> &SymbolMap,
+ std::vector<MachRelocationEntry> &Relocs) {
+ // If this is a local symbol plus an offset or a difference, then we need a
+ // scattered relocation entry.
+ if (Fixup.Value.getSymB()) // a - b
+ return ComputeScatteredRelocationInfo(Asm, Fixup, SymbolMap, Relocs);
+ if (Fixup.Value.getSymA() && Fixup.Value.getConstant())
+ if (!Fixup.Value.getSymA()->isUndefined())
+ return ComputeScatteredRelocationInfo(Asm, Fixup, SymbolMap, Relocs);
+
+ // See <reloc.h>.
+ uint32_t Address = Fixup.Fragment->getOffset() + Fixup.Offset;
+ uint32_t Value = 0;
+ unsigned Index = 0;
+ unsigned IsPCRel = 0;
+ unsigned IsExtern = 0;
+ unsigned Type = 0;
+
+ if (Fixup.Value.isAbsolute()) { // constant
+ // SymbolNum of 0 indicates the absolute section.
+ Type = RIT_Vanilla;
+ Value = 0;
+ llvm_unreachable("FIXME: Not yet implemented!");
+ } else {
+ const MCSymbol *Symbol = Fixup.Value.getSymA();
+ MCSymbolData *SD = SymbolMap.lookup(Symbol);
+
+ if (Symbol->isUndefined()) {
+ IsExtern = 1;
+ Index = SD->getIndex();
+ Value = 0;
+ } else {
+ // The index is the section ordinal.
+ //
+ // FIXME: O(N)
+ Index = 1;
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it, ++Index)
+ if (&*it == SD->getFragment()->getParent())
+ break;
+ Value = SD->getFragment()->getAddress() + SD->getOffset();
+ }
+
+ Type = RIT_Vanilla;
+ }
+
+ // The value which goes in the fixup is current value of the expression.
+ Fixup.FixedValue = Value + Fixup.Value.getConstant();
+
+ unsigned Log2Size = Log2_32(Fixup.Size);
+ assert((1U << Log2Size) == Fixup.Size && "Invalid fixup size!");
+
+ // struct relocation_info (8 bytes)
+ MachRelocationEntry MRE;
+ MRE.Word0 = Address;
+ MRE.Word1 = ((Index << 0) |
+ (IsPCRel << 24) |
+ (Log2Size << 25) |
+ (IsExtern << 27) |
+ (Type << 28));
+ Relocs.push_back(MRE);
+ }
+
+ void BindIndirectSymbols(MCAssembler &Asm,
+ DenseMap<const MCSymbol*,MCSymbolData*> &SymbolMap) {
+ // This is the point where 'as' creates actual symbols for indirect symbols
+ // (in the following two passes). It would be easier for us to do this
+ // sooner when we see the attribute, but that makes getting the order in the
+ // symbol table much more complicated than it is worth.
+ //
+ // FIXME: Revisit this when the dust settles.
+
+ // Bind non lazy symbol pointers first.
+ for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
+ ie = Asm.indirect_symbol_end(); it != ie; ++it) {
+ // FIXME: cast<> support!
+ const MCSectionMachO &Section =
+ static_cast<const MCSectionMachO&>(it->SectionData->getSection());
+
+ unsigned Type =
+ Section.getTypeAndAttributes() & MCSectionMachO::SECTION_TYPE;
+ if (Type != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS)
+ continue;
+
+ MCSymbolData *&Entry = SymbolMap[it->Symbol];
+ if (!Entry)
+ Entry = new MCSymbolData(*it->Symbol, 0, 0, &Asm);
+ }
+
+ // Then lazy symbol pointers and symbol stubs.
+ for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
+ ie = Asm.indirect_symbol_end(); it != ie; ++it) {
+ // FIXME: cast<> support!
+ const MCSectionMachO &Section =
+ static_cast<const MCSectionMachO&>(it->SectionData->getSection());
+
+ unsigned Type =
+ Section.getTypeAndAttributes() & MCSectionMachO::SECTION_TYPE;
+ if (Type != MCSectionMachO::S_LAZY_SYMBOL_POINTERS &&
+ Type != MCSectionMachO::S_SYMBOL_STUBS)
+ continue;
+
+ MCSymbolData *&Entry = SymbolMap[it->Symbol];
+ if (!Entry) {
+ Entry = new MCSymbolData(*it->Symbol, 0, 0, &Asm);
+
+ // Set the symbol type to undefined lazy, but only on construction.
+ //
+ // FIXME: Do not hardcode.
+ Entry->setFlags(Entry->getFlags() | 0x0001);
+ }
+ }
+ }
+
+ /// 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.
+ void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
+ std::vector<MachSymbolData> &LocalSymbolData,
+ std::vector<MachSymbolData> &ExternalSymbolData,
+ std::vector<MachSymbolData> &UndefinedSymbolData) {
+ // Build section lookup table.
+ 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!");
+
+ // Index 0 is always the empty string.
+ StringMap<uint64_t> StringIndexMap;
+ StringTable += '\x00';
+
+ // Build the symbol arrays and the string table, but only for non-local
+ // symbols.
+ //
+ // The particular order that we collect the symbols and create the string
+ // table, then sort the symbols is chosen to match 'as'. Even though it
+ // doesn't matter for correctness, this is important for letting us diff .o
+ // files.
+ for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
+ ie = Asm.symbol_end(); it != ie; ++it) {
+ MCSymbol &Symbol = it->getSymbol();
+
+ // Ignore assembler temporaries.
+ if (it->getSymbol().isTemporary())
+ 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);
+ }
+ }
+
+ // Now add the data for local symbols.
+ for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
+ ie = Asm.symbol_end(); it != ie; ++it) {
+ MCSymbol &Symbol = it->getSymbol();
+
+ // Ignore assembler temporaries.
+ if (it->getSymbol().isTemporary())
+ 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);
+ }
+ }
+
+ // External and undefined symbols are required to be in lexicographic order.
+ std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
+ std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
+
+ // Set the symbol indices.
+ 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++);
+
+ // The string table is padded to a multiple of 4.
+ //
+ // FIXME: Check to see if this varies per arch.
+ while (StringTable.size() % 4)
+ StringTable += '\x00';
+ }
+
+ void WriteObject(MCAssembler &Asm) {
+ unsigned NumSections = Asm.size();
+
+ // Compute the symbol -> symbol data map.
+ //
+ // FIXME: This should not be here.
+ DenseMap<const MCSymbol*, MCSymbolData *> SymbolMap;
+ for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
+ ie = Asm.symbol_end(); it != ie; ++it)
+ SymbolMap[&it->getSymbol()] = it;
+
+ // Create symbol data for any indirect symbols.
+ BindIndirectSymbols(Asm, SymbolMap);
+
+ // Compute symbol table information.
+ SmallString<256> StringTable;
+ std::vector<MachSymbolData> LocalSymbolData;
+ std::vector<MachSymbolData> ExternalSymbolData;
+ std::vector<MachSymbolData> UndefinedSymbolData;
+ unsigned NumSymbols = Asm.symbol_size();
+
+ // No symbol table command is written if there are no symbols.
+ if (NumSymbols)
+ ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
+ UndefinedSymbolData);
+
+ // The section data starts after the header, the segment load command (and
+ // section headers) and the symbol table.
+ unsigned NumLoadCommands = 1;
+ uint64_t LoadCommandsSize =
+ SegmentLoadCommand32Size + NumSections * Section32Size;
+
+ // Add the symbol table load command sizes, if used.
+ if (NumSymbols) {
+ NumLoadCommands += 2;
+ LoadCommandsSize += SymtabLoadCommandSize + DysymtabLoadCommandSize;
+ }
+
+ // Compute the total size of the section data, as well as its file size and
+ // vm size.
+ uint64_t SectionDataStart = Header32Size + LoadCommandsSize;
+ uint64_t SectionDataSize = 0;
+ uint64_t SectionDataFileSize = 0;
+ uint64_t VMSize = 0;
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
+ MCSectionData &SD = *it;
+
+ VMSize = std::max(VMSize, SD.getAddress() + SD.getSize());
+
+ if (isVirtualSection(SD.getSection()))
+ continue;
+
+ SectionDataSize = std::max(SectionDataSize,
+ SD.getAddress() + SD.getSize());
+ SectionDataFileSize = std::max(SectionDataFileSize,
+ SD.getAddress() + SD.getFileSize());
+ }
+
+ // The section data is passed to 4 bytes.
+ //
+ // FIXME: Is this machine dependent?
+ unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
+ SectionDataFileSize += SectionDataPadding;
+
+ // Write the prolog, starting with the header and load command...
+ WriteHeader32(NumLoadCommands, LoadCommandsSize,
+ Asm.getSubsectionsViaSymbols());
+ WriteSegmentLoadCommand32(NumSections, VMSize,
+ SectionDataStart, SectionDataSize);
+
+ // ... and then the section headers.
+ //
+ // We also compute the section relocations while we do this. Note that
+ // compute relocation info will also update the fixup to have the correct
+ // value; this will be overwrite the appropriate data in the fragment when
+ // it is written.
+ std::vector<MachRelocationEntry> RelocInfos;
+ uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
+ for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie;
+ ++it) {
+ MCSectionData &SD = *it;
+
+ // The assembler writes relocations in the reverse order they were seen.
+ //
+ // FIXME: It is probably more complicated than this.
+ unsigned NumRelocsStart = RelocInfos.size();
+ for (unsigned i = 0, e = SD.fixup_size(); i != e; ++i)
+ ComputeRelocationInfo(Asm, SD.getFixups()[e - i - 1], SymbolMap,
+ RelocInfos);
+
+ unsigned NumRelocs = RelocInfos.size() - NumRelocsStart;
+ uint64_t SectionStart = SectionDataStart + SD.getAddress();
+ WriteSection32(SD, SectionStart, RelocTableEnd, NumRelocs);
+ RelocTableEnd += NumRelocs * RelocationInfoSize;
+ }
+
+ // Write the symbol table load command, if used.
+ 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 used, the indirect symbols are written after the section data.
+ if (NumIndirectSymbols)
+ IndirectSymbolOffset = RelocTableEnd;
+
+ // The symbol table is written after the indirect symbol data.
+ uint64_t SymbolTableOffset = RelocTableEnd + IndirectSymbolSize;
+
+ // The string table is written after symbol table.
+ uint64_t StringTableOffset =
+ SymbolTableOffset + NumSymTabSymbols * Nlist32Size;
+ WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
+ StringTableOffset, StringTable.size());
+
+ WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
+ FirstExternalSymbol, NumExternalSymbols,
+ FirstUndefinedSymbol, NumUndefinedSymbols,
+ IndirectSymbolOffset, NumIndirectSymbols);
+ }
+
+ // Write the actual section data.
+ for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
+ WriteFileData(OS, *it, *this);
+
+ // Write the extra padding.
+ WriteZeros(SectionDataPadding);
+
+ // Write the relocation entries.
+ for (unsigned i = 0, e = RelocInfos.size(); i != e; ++i) {
+ Write32(RelocInfos[i].Word0);
+ Write32(RelocInfos[i].Word1);
+ }
+
+ // Write the symbol table data, if used.
+ if (NumSymbols) {
+ // Write the indirect symbol entries.
+ for (MCAssembler::indirect_symbol_iterator
+ it = Asm.indirect_symbol_begin(),
+ ie = Asm.indirect_symbol_end(); it != ie; ++it) {
+ // Indirect symbols in the non lazy symbol pointer section have some
+ // special handling.
+ const MCSectionMachO &Section =
+ static_cast<const MCSectionMachO&>(it->SectionData->getSection());
+ unsigned Type =
+ Section.getTypeAndAttributes() & MCSectionMachO::SECTION_TYPE;
+ if (Type == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) {
+ // If this symbol is defined and internal, mark it as such.
+ if (it->Symbol->isDefined() &&
+ !SymbolMap.lookup(it->Symbol)->isExternal()) {
+ uint32_t Flags = ISF_Local;
+ if (it->Symbol->isAbsolute())
+ Flags |= ISF_Absolute;
+ Write32(Flags);
+ continue;
+ }
+ }
+
+ Write32(SymbolMap[it->Symbol]->getIndex());
+ }
+
+ // FIXME: Check that offsets match computed ones.
+
+ // Write the symbol table entries.
+ for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
+ WriteNlist32(LocalSymbolData[i]);
+ for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
+ WriteNlist32(ExternalSymbolData[i]);
+ for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
+ WriteNlist32(UndefinedSymbolData[i]);
+
+ // Write the string table.
+ OS << StringTable.str();
+ }
+ }
+};
/* *** */
-MCFragment::MCFragment(MCSectionData *SD)
+MCFragment::MCFragment() : Kind(FragmentType(~0)) {
+}
+
+MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
+ : Kind(_Kind),
+ Parent(_Parent),
+ FileSize(~UINT64_C(0))
{
- if (SD)
- SD->getFragmentList().push_back(this);
+ if (Parent)
+ Parent->getFragmentList().push_back(this);
+}
+
+MCFragment::~MCFragment() {
+}
+
+uint64_t MCFragment::getAddress() const {
+ assert(getParent() && "Missing Section!");
+ return getParent()->getAddress() + Offset;
}
/* *** */
-MCSectionData::MCSectionData() : Section(*(MCSection*)0) {}
+MCSectionData::MCSectionData() : Section(0) {}
MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
- : Section(_Section),
+ : Section(&_Section),
Alignment(1),
- FileOffset(0),
- FileSize(0)
+ Address(~UINT64_C(0)),
+ Size(~UINT64_C(0)),
+ FileSize(~UINT64_C(0)),
+ LastFixupLookup(~0)
{
if (A)
A->getSectionList().push_back(this);
}
-void MCSectionData::WriteFileData(raw_ostream &OS) const {
-
+const MCSectionData::Fixup *
+MCSectionData::LookupFixup(const MCFragment *Fragment, uint64_t Offset) const {
+ // Use a one level cache to turn the common case of accessing the fixups in
+ // order into O(1) instead of O(N).
+ unsigned i = LastFixupLookup, Count = Fixups.size(), End = Fixups.size();
+ if (i >= End)
+ i = 0;
+ while (Count--) {
+ const Fixup &F = Fixups[i];
+ if (F.Fragment == Fragment && F.Offset == Offset) {
+ LastFixupLookup = i;
+ return &F;
+ }
+
+ ++i;
+ if (i == End)
+ i = 0;
+ }
+
+ return 0;
+}
+
+/* *** */
+
+MCSymbolData::MCSymbolData() : Symbol(*(MCSymbol*)0) {}
+
+MCSymbolData::MCSymbolData(MCSymbol &_Symbol, MCFragment *_Fragment,
+ uint64_t _Offset, MCAssembler *A)
+ : Symbol(_Symbol), Fragment(_Fragment), Offset(_Offset),
+ IsExternal(false), IsPrivateExtern(false),
+ CommonSize(0), CommonAlign(0), Flags(0), Index(0)
+{
+ if (A)
+ A->getSymbolList().push_back(this);
}
/* *** */
-MCAssembler::MCAssembler(raw_ostream &_OS) : OS(_OS) {}
+MCAssembler::MCAssembler(MCContext &_Context, raw_ostream &_OS)
+ : Context(_Context), OS(_OS), SubsectionsViaSymbols(false)
+{
+}
MCAssembler::~MCAssembler() {
}
+void MCAssembler::LayoutSection(MCSectionData &SD) {
+ uint64_t Address = SD.getAddress();
+
+ for (MCSectionData::iterator it = SD.begin(), ie = SD.end(); it != ie; ++it) {
+ MCFragment &F = *it;
+
+ F.setOffset(Address - SD.getAddress());
+
+ // Evaluate fragment size.
+ switch (F.getKind()) {
+ case MCFragment::FT_Align: {
+ MCAlignFragment &AF = cast<MCAlignFragment>(F);
+
+ uint64_t Size = OffsetToAlignment(Address, AF.getAlignment());
+ if (Size > AF.getMaxBytesToEmit())
+ AF.setFileSize(0);
+ else
+ AF.setFileSize(Size);
+ break;
+ }
+
+ case MCFragment::FT_Data:
+ F.setFileSize(F.getMaxFileSize());
+ break;
+
+ case MCFragment::FT_Fill: {
+ MCFillFragment &FF = cast<MCFillFragment>(F);
+
+ F.setFileSize(F.getMaxFileSize());
+
+ // If the fill value is constant, thats it.
+ if (FF.getValue().isAbsolute())
+ break;
+
+ // Otherwise, add fixups for the values.
+ for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
+ MCSectionData::Fixup Fix(F, i * FF.getValueSize(),
+ FF.getValue(),FF.getValueSize());
+ SD.getFixups().push_back(Fix);
+ }
+ break;
+ }
+
+ case MCFragment::FT_Org: {
+ MCOrgFragment &OF = cast<MCOrgFragment>(F);
+
+ if (!OF.getOffset().isAbsolute())
+ llvm_unreachable("FIXME: Not yet implemented!");
+ uint64_t OrgOffset = OF.getOffset().getConstant();
+ uint64_t Offset = Address - SD.getAddress();
+
+ // FIXME: We need a way to communicate this error.
+ if (OrgOffset < Offset)
+ llvm_report_error("invalid .org offset '" + Twine(OrgOffset) +
+ "' (at offset '" + Twine(Offset) + "'");
+
+ F.setFileSize(OrgOffset - Offset);
+ break;
+ }
+
+ case MCFragment::FT_ZeroFill: {
+ MCZeroFillFragment &ZFF = cast<MCZeroFillFragment>(F);
+
+ // Align the fragment offset; it is safe to adjust the offset freely since
+ // this is only in virtual sections.
+ uint64_t Aligned = RoundUpToAlignment(Address, ZFF.getAlignment());
+ F.setOffset(Aligned - SD.getAddress());
+
+ // FIXME: This is misnamed.
+ F.setFileSize(ZFF.getSize());
+ break;
+ }
+ }
+
+ Address += F.getFileSize();
+ }
+
+ // Set the section sizes.
+ SD.setSize(Address - SD.getAddress());
+ if (isVirtualSection(SD.getSection()))
+ SD.setFileSize(0);
+ else
+ SD.setFileSize(Address - SD.getAddress());
+}
+
+/// WriteFileData - Write the \arg F data to the output file.
+static void WriteFileData(raw_ostream &OS, const MCFragment &F,
+ MachObjectWriter &MOW) {
+ uint64_t Start = OS.tell();
+ (void) Start;
+
+ ++EmittedFragments;
+
+ // FIXME: Embed in fragments instead?
+ switch (F.getKind()) {
+ case MCFragment::FT_Align: {
+ MCAlignFragment &AF = cast<MCAlignFragment>(F);
+ uint64_t Count = AF.getFileSize() / AF.getValueSize();
+
+ // FIXME: This error shouldn't actually occur (the front end should emit
+ // multiple .align directives to enforce the semantics it wants), but is
+ // severe enough that we want to report it. How to handle this?
+ if (Count * AF.getValueSize() != AF.getFileSize())
+ llvm_report_error("undefined .align directive, value size '" +
+ Twine(AF.getValueSize()) +
+ "' is not a divisor of padding size '" +
+ Twine(AF.getFileSize()) + "'");
+
+ for (uint64_t i = 0; i != Count; ++i) {
+ switch (AF.getValueSize()) {
+ default:
+ assert(0 && "Invalid size!");
+ case 1: MOW.Write8 (uint8_t (AF.getValue())); break;
+ case 2: MOW.Write16(uint16_t(AF.getValue())); break;
+ case 4: MOW.Write32(uint32_t(AF.getValue())); break;
+ case 8: MOW.Write64(uint64_t(AF.getValue())); break;
+ }
+ }
+ break;
+ }
+
+ case MCFragment::FT_Data:
+ OS << cast<MCDataFragment>(F).getContents().str();
+ break;
+
+ case MCFragment::FT_Fill: {
+ MCFillFragment &FF = cast<MCFillFragment>(F);
+
+ int64_t Value = 0;
+ if (FF.getValue().isAbsolute())
+ Value = FF.getValue().getConstant();
+ for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
+ if (!FF.getValue().isAbsolute()) {
+ // Find the fixup.
+ //
+ // FIXME: Find a better way to write in the fixes.
+ const MCSectionData::Fixup *Fixup =
+ F.getParent()->LookupFixup(&F, i * FF.getValueSize());
+ assert(Fixup && "Missing fixup for fill value!");
+ Value = Fixup->FixedValue;
+ }
+
+ switch (FF.getValueSize()) {
+ default:
+ assert(0 && "Invalid size!");
+ case 1: MOW.Write8 (uint8_t (Value)); break;
+ case 2: MOW.Write16(uint16_t(Value)); break;
+ case 4: MOW.Write32(uint32_t(Value)); break;
+ case 8: MOW.Write64(uint64_t(Value)); break;
+ }
+ }
+ break;
+ }
+
+ case MCFragment::FT_Org: {
+ MCOrgFragment &OF = cast<MCOrgFragment>(F);
+
+ for (uint64_t i = 0, e = OF.getFileSize(); i != e; ++i)
+ MOW.Write8(uint8_t(OF.getValue()));
+
+ break;
+ }
+
+ case MCFragment::FT_ZeroFill: {
+ assert(0 && "Invalid zero fill fragment in concrete section!");
+ break;
+ }
+ }
+
+ assert(OS.tell() - Start == F.getFileSize());
+}
+
+/// WriteFileData - Write the \arg SD data to the output file.
+static void WriteFileData(raw_ostream &OS, const MCSectionData &SD,
+ MachObjectWriter &MOW) {
+ // Ignore virtual sections.
+ if (isVirtualSection(SD.getSection())) {
+ assert(SD.getFileSize() == 0);
+ return;
+ }
+
+ uint64_t Start = OS.tell();
+ (void) Start;
+
+ for (MCSectionData::const_iterator it = SD.begin(),
+ ie = SD.end(); it != ie; ++it)
+ WriteFileData(OS, *it, MOW);
+
+ // Add section padding.
+ assert(SD.getFileSize() >= SD.getSize() && "Invalid section sizes!");
+ MOW.WriteZeros(SD.getFileSize() - SD.getSize());
+
+ assert(OS.tell() - Start == SD.getFileSize());
+}
+
void MCAssembler::Finish() {
- unsigned NumSections = Sections.size();
-
- // Compute the file offsets so we can write in a single pass.
- uint64_t Offset = MachObjectWriter::getPrologSize32(NumSections);
+ // Layout the concrete sections and fragments.
+ uint64_t Address = 0;
+ MCSectionData *Prev = 0;
for (iterator it = begin(), ie = end(); it != ie; ++it) {
- it->setFileOffset(Offset);
- Offset += it->getFileSize();
+ MCSectionData &SD = *it;
+
+ // Skip virtual sections.
+ if (isVirtualSection(SD.getSection()))
+ continue;
+
+ // Align this section if necessary by adding padding bytes to the previous
+ // section.
+ if (uint64_t Pad = OffsetToAlignment(Address, it->getAlignment())) {
+ assert(Prev && "Missing prev section!");
+ Prev->setFileSize(Prev->getFileSize() + Pad);
+ Address += Pad;
+ }
+
+ // Layout the section fragments and its size.
+ SD.setAddress(Address);
+ LayoutSection(SD);
+ Address += SD.getFileSize();
+
+ Prev = &SD;
}
- MachObjectWriter MOW(OS);
+ // Layout the virtual sections.
+ for (iterator it = begin(), ie = end(); it != ie; ++it) {
+ MCSectionData &SD = *it;
- // Write the prolog, starting with the header and load command...
- MOW.WriteHeader32(NumSections);
- MOW.WriteSegmentLoadCommand32(NumSections);
-
- // ... and then the section headers.
- for (iterator it = begin(), ie = end(); it != ie; ++it)
- MOW.WriteSection32(*it);
+ if (!isVirtualSection(SD.getSection()))
+ continue;
+
+ SD.setAddress(Address);
+ LayoutSection(SD);
+ Address += SD.getSize();
+ }
+
+ // Write the object file.
+ MachObjectWriter MOW(OS);
+ MOW.WriteObject(*this);
- // Finally, write the section data.
- for (iterator it = begin(), ie = end(); it != ie; ++it)
- it->WriteFileData(OS);
-
OS.flush();
}
projects / oota-llvm.git / blobdiff