From 2df4ceba15c130005967ee9e5fb4aa5568de1b0c Mon Sep 17 00:00:00 2001 From: Daniel Dunbar Date: Fri, 19 Mar 2010 10:43:15 +0000 Subject: [PATCH] MC/Mach-O: Move to MachObjectWriter.{h,cpp}. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98952 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/MC/MachObjectWriter.h | 43 ++ lib/MC/CMakeLists.txt | 1 + lib/MC/MCAssembler.cpp | 821 +------------------------- lib/MC/MCObjectWriter.cpp | 2 +- lib/MC/MachObjectWriter.cpp | 897 +++++++++++++++++++++++++++++ 5 files changed, 943 insertions(+), 821 deletions(-) create mode 100644 include/llvm/MC/MachObjectWriter.h create mode 100644 lib/MC/MachObjectWriter.cpp diff --git a/include/llvm/MC/MachObjectWriter.h b/include/llvm/MC/MachObjectWriter.h new file mode 100644 index 00000000000..3e3305f083a --- /dev/null +++ b/include/llvm/MC/MachObjectWriter.h @@ -0,0 +1,43 @@ +//===-- llvm/MC/MachObjectWriter.h - Mach-O File Writer ---------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_MC_MACHOBJECTWRITER_H +#define LLVM_MC_MACHOBJECTWRITER_H + +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/Support/raw_ostream.h" +#include + +namespace llvm { +class MCAsmFixup; +class MCAssembler; +class MCDataFragment; +class MCValue; +class raw_ostream; + +class MachObjectWriter : public MCObjectWriter { + void *Impl; + +public: + MachObjectWriter(raw_ostream &OS, bool Is64Bit, bool IsLittleEndian = true); + virtual ~MachObjectWriter(); + + virtual void ExecutePostLayoutBinding(MCAssembler &Asm); + + virtual void RecordRelocation(const MCAssembler &Asm, + const MCDataFragment &Fragment, + const MCAsmFixup &Fixup, MCValue Target, + uint64_t &FixedValue); + + virtual void WriteObject(const MCAssembler &Asm); +}; + +} // End llvm namespace + +#endif diff --git a/lib/MC/CMakeLists.txt b/lib/MC/CMakeLists.txt index 682fe24217a..dba0e143565 100644 --- a/lib/MC/CMakeLists.txt +++ b/lib/MC/CMakeLists.txt @@ -19,5 +19,6 @@ add_llvm_library(LLVMMC MCStreamer.cpp MCSymbol.cpp MCValue.cpp + MachObjectWriter.cpp TargetAsmBackend.cpp ) diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp index f1847df2f14..6e5f73ff44c 100644 --- a/lib/MC/MCAssembler.cpp +++ b/lib/MC/MCAssembler.cpp @@ -12,17 +12,13 @@ #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/MCValue.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/SmallString.h" +#include "llvm/MC/MachObjectWriter.h" #include "llvm/ADT/Statistic.h" #include "llvm/ADT/StringExtras.h" -#include "llvm/ADT/StringMap.h" #include "llvm/ADT/Twine.h" #include "llvm/Support/ErrorHandling.h" -#include "llvm/Support/MachO.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Support/Debug.h" #include "llvm/Target/TargetRegistry.h" @@ -34,8 +30,6 @@ #include using namespace llvm; -class MachObjectWriter; - STATISTIC(EmittedFragments, "Number of emitted assembler fragments"); // FIXME FIXME FIXME: There are number of places in this file where we convert @@ -43,19 +37,6 @@ STATISTIC(EmittedFragments, "Number of emitted assembler fragments"); // object file, which may truncate it. We should detect that truncation where // invalid and report errors back. -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 FK_Data_2: return 1; - case X86::reloc_pcrel_4byte: - case X86::reloc_riprel_4byte: - case FK_Data_4: return 2; - case FK_Data_8: return 3; - } -} - static bool isFixupKindPCRel(unsigned Kind) { switch (Kind) { default: @@ -67,806 +48,6 @@ static bool isFixupKindPCRel(unsigned Kind) { } } -class MachObjectWriter : public MCObjectWriter { - // See . - 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 - }; - - // See . - 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 - // . 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(); - } - }; - - unsigned Is64Bit : 1; - - /// @name Relocation Data - /// @{ - - struct MachRelocationEntry { - uint32_t Word0; - uint32_t Word1; - }; - - llvm::DenseMap > Relocations; - - /// @} - /// @name Symbol Table Data - - SmallString<256> StringTable; - std::vector LocalSymbolData; - std::vector ExternalSymbolData; - std::vector UndefinedSymbolData; - - /// @} - -public: - MachObjectWriter(raw_ostream &_OS, bool _Is64Bit, bool _IsLittleEndian = true) - : MCObjectWriter(_OS, _IsLittleEndian), Is64Bit(_Is64Bit) { - } - - void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize, - bool SubsectionsViaSymbols) { - uint32_t Flags = 0; - - if (SubsectionsViaSymbols) - Flags |= HF_SubsectionsViaSymbols; - - // struct mach_header (28 bytes) or - // struct mach_header_64 (32 bytes) - - uint64_t Start = OS.tell(); - (void) Start; - - Write32(Is64Bit ? Header_Magic64 : Header_Magic32); - - // FIXME: Support cputype. - Write32(Is64Bit ? MachO::CPUTypeX86_64 : MachO::CPUTypeI386); - // FIXME: Support cpusubtype. - Write32(MachO::CPUSubType_I386_ALL); - Write32(HFT_Object); - Write32(NumLoadCommands); // Object files have a single load command, the - // segment. - Write32(LoadCommandsSize); - Write32(Flags); - if (Is64Bit) - Write32(0); // reserved - - assert(OS.tell() - Start == Is64Bit ? Header64Size : Header32Size); - } - - /// WriteSegmentLoadCommand - Write a segment load command. - /// - /// \arg NumSections - The number of sections in this segment. - /// \arg SectionDataSize - The total size of the sections. - void WriteSegmentLoadCommand(unsigned NumSections, - uint64_t VMSize, - uint64_t SectionDataStartOffset, - uint64_t SectionDataSize) { - // struct segment_command (56 bytes) or - // struct segment_command_64 (72 bytes) - - 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); // vmaddr - Write64(VMSize); // vmsize - Write64(SectionDataStartOffset); // file offset - Write64(SectionDataSize); // file size - } else { - Write32(0); // vmaddr - Write32(VMSize); // vmsize - Write32(SectionDataStartOffset); // file offset - Write32(SectionDataSize); // file size - } - Write32(0x7); // maxprot - Write32(0x7); // initprot - Write32(NumSections); - Write32(0); // flags - - assert(OS.tell() - Start == SegmentLoadCommandSize); - } - - void WriteSection(const MCAssembler &Asm, const MCSectionData &SD, - uint64_t FileOffset, uint64_t RelocationsStart, - unsigned NumRelocations) { - // The offset is unused for virtual sections. - if (Asm.getBackend().isVirtualSection(SD.getSection())) { - assert(SD.getFileSize() == 0 && "Invalid file size!"); - FileOffset = 0; - } - - // struct section (68 bytes) or - // struct section_64 (80 bytes) - - uint64_t Start = OS.tell(); - (void) Start; - - // FIXME: cast<> support! - const MCSectionMachO &Section = - static_cast(SD.getSection()); - WriteBytes(Section.getSectionName(), 16); - WriteBytes(Section.getSegmentName(), 16); - if (Is64Bit) { - Write64(SD.getAddress()); // address - Write64(SD.getSize()); // size - } else { - Write32(SD.getAddress()); // address - Write32(SD.getSize()); // size - } - 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(0); // reserved1 - Write32(Section.getStubSize()); // reserved2 - if (Is64Bit) - Write32(0); // reserved3 - - assert(OS.tell() - Start == Is64Bit ? Section64Size : 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 WriteNlist(MachSymbolData &MSD) { - MCSymbolData &Data = *MSD.SymbolData; - const MCSymbol &Symbol = Data.getSymbol(); - uint8_t Type = 0; - uint16_t Flags = Data.getFlags(); - uint32_t Address = 0; - - // Set the N_TYPE bits. See . - // - // 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.getAddress(); - } - } 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); - if (Is64Bit) - Write64(Address); - else - Write32(Address); - } - - void RecordScatteredRelocation(const MCAssembler &Asm, - const MCFragment &Fragment, - const MCAsmFixup &Fixup, MCValue Target, - uint64_t &FixedValue) { - uint32_t Address = Fragment.getOffset() + Fixup.Offset; - unsigned IsPCRel = isFixupKindPCRel(Fixup.Kind); - unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind); - unsigned Type = RIT_Vanilla; - - // See . - const MCSymbol *A = &Target.getSymA()->getSymbol(); - MCSymbolData *A_SD = &Asm.getSymbolData(*A); - - if (!A_SD->getFragment()) - llvm_report_error("symbol '" + A->getName() + - "' can not be undefined in a subtraction expression"); - - uint32_t Value = A_SD->getAddress(); - uint32_t Value2 = 0; - - if (const MCSymbolRefExpr *B = Target.getSymB()) { - MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol()); - - if (!B_SD->getFragment()) - llvm_report_error("symbol '" + B->getSymbol().getName() + - "' can not be undefined in a subtraction expression"); - - // Select the appropriate difference relocation type. - // - // Note that there is no longer any semantic difference between these two - // relocation types from the linkers point of view, this is done solely - // for pedantic compatibility with 'as'. - Type = A_SD->isExternal() ? RIT_Difference : RIT_LocalDifference; - Value2 = B_SD->getAddress(); - } - - // Relocations are written out in reverse order, so the PAIR comes first. - 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 = ((Address << 0) | - (Type << 24) | - (Log2Size << 28) | - (IsPCRel << 30) | - RF_Scattered); - MRE.Word1 = Value; - Relocations[Fragment.getParent()].push_back(MRE); - } - - virtual void RecordRelocation(const MCAssembler &Asm, - const MCDataFragment &Fragment, - const MCAsmFixup &Fixup, MCValue Target, - uint64_t &FixedValue) { - unsigned IsPCRel = isFixupKindPCRel(Fixup.Kind); - unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind); - - // If this is a difference or a defined symbol plus an offset, then we need - // a scattered relocation entry. - uint32_t Offset = Target.getConstant(); - if (IsPCRel) - Offset += 1 << Log2Size; - if (Target.getSymB() || - (Target.getSymA() && !Target.getSymA()->getSymbol().isUndefined() && - Offset)) { - RecordScatteredRelocation(Asm, Fragment, Fixup, Target, FixedValue); - return; - } - - // See . - uint32_t Address = Fragment.getOffset() + Fixup.Offset; - uint32_t Value = 0; - unsigned Index = 0; - unsigned IsExtern = 0; - unsigned Type = 0; - - if (Target.isAbsolute()) { // constant - // SymbolNum of 0 indicates the absolute section. - // - // FIXME: Currently, these are never generated (see code below). I cannot - // find a case where they are actually emitted. - Type = RIT_Vanilla; - Value = 0; - } else { - const MCSymbol *Symbol = &Target.getSymA()->getSymbol(); - MCSymbolData *SD = &Asm.getSymbolData(*Symbol); - - if (Symbol->isUndefined()) { - IsExtern = 1; - Index = SD->getIndex(); - Value = 0; - } else { - // The index is the section ordinal. - // - // FIXME: O(N) - Index = 1; - MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); - for (; it != ie; ++it, ++Index) - if (&*it == SD->getFragment()->getParent()) - break; - assert(it != ie && "Unable to find section index!"); - Value = SD->getAddress(); - } - - Type = RIT_Vanilla; - } - - // struct relocation_info (8 bytes) - MachRelocationEntry MRE; - MRE.Word0 = Address; - MRE.Word1 = ((Index << 0) | - (IsPCRel << 24) | - (Log2Size << 25) | - (IsExtern << 27) | - (Type << 28)); - Relocations[Fragment.getParent()].push_back(MRE); - } - - void BindIndirectSymbols(MCAssembler &Asm) { - // 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(it->SectionData->getSection()); - - if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) - continue; - - Asm.getOrCreateSymbolData(*it->Symbol); - } - - // 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(it->SectionData->getSection()); - - if (Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS && - Section.getType() != MCSectionMachO::S_SYMBOL_STUBS) - continue; - - // Set the symbol type to undefined lazy, but only on construction. - // - // FIXME: Do not hardcode. - bool Created; - MCSymbolData &Entry = Asm.getOrCreateSymbolData(*it->Symbol, &Created); - if (Created) - 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 &LocalSymbolData, - std::vector &ExternalSymbolData, - std::vector &UndefinedSymbolData) { - // Build section lookup table. - DenseMap 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 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) { - const MCSymbol &Symbol = it->getSymbol(); - - // Ignore non-linker visible symbols. - if (!Asm.isSymbolLinkerVisible(it)) - 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) { - const MCSymbol &Symbol = it->getSymbol(); - - // Ignore non-linker visible symbols. - if (!Asm.isSymbolLinkerVisible(it)) - 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. - while (StringTable.size() % 4) - StringTable += '\x00'; - } - - virtual void ExecutePostLayoutBinding(MCAssembler &Asm) { - // Create symbol data for any indirect symbols. - BindIndirectSymbols(Asm); - - // Compute symbol table information and bind symbol indices. - ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData, - UndefinedSymbolData); - } - - virtual void WriteObject(const MCAssembler &Asm) { - unsigned NumSections = Asm.size(); - - // The section data starts after the header, the segment load command (and - // section headers) and the symbol table. - unsigned NumLoadCommands = 1; - uint64_t LoadCommandsSize = Is64Bit ? - SegmentLoadCommand64Size + NumSections * Section64Size : - SegmentLoadCommand32Size + NumSections * Section32Size; - - // Add the symbol table load command sizes, if used. - unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() + - UndefinedSymbolData.size(); - 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 = (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; - - VMSize = std::max(VMSize, SD.getAddress() + SD.getSize()); - - if (Asm.getBackend().isVirtualSection(SD.getSection())) - continue; - - SectionDataSize = std::max(SectionDataSize, - SD.getAddress() + SD.getSize()); - SectionDataFileSize = std::max(SectionDataFileSize, - SD.getAddress() + SD.getFileSize()); - } - - // The section data is padded 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... - WriteHeader(NumLoadCommands, LoadCommandsSize, - Asm.getSubsectionsViaSymbols()); - WriteSegmentLoadCommand(NumSections, VMSize, - SectionDataStart, SectionDataSize); - - // ... and then the section headers. - uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize; - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - std::vector &Relocs = Relocations[it]; - unsigned NumRelocs = Relocs.size(); - uint64_t SectionStart = SectionDataStart + it->getAddress(); - WriteSection(Asm, *it, 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 * (Is64Bit ? Nlist64Size : - Nlist32Size); - WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols, - StringTableOffset, StringTable.size()); - - WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols, - FirstExternalSymbol, NumExternalSymbols, - FirstUndefinedSymbol, NumUndefinedSymbols, - IndirectSymbolOffset, NumIndirectSymbols); - } - - // Write the actual section data. - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) - Asm.WriteSectionData(it, this); - - // Write the extra padding. - WriteZeros(SectionDataPadding); - - // Write the relocation entries. - for (MCAssembler::const_iterator it = Asm.begin(), - ie = Asm.end(); it != ie; ++it) { - // Write the section relocation entries, in reverse order to match 'as' - // (approximately, the exact algorithm is more complicated than this). - std::vector &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); - } - } - - // Write the symbol table data, if used. - if (NumSymbols) { - // Write the indirect symbol entries. - for (MCAssembler::const_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(it->SectionData->getSection()); - if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) { - // If this symbol is defined and internal, mark it as such. - 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()); - } - - // FIXME: Check that offsets match computed ones. - - // Write the symbol table entries. - for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) - WriteNlist(LocalSymbolData[i]); - for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) - WriteNlist(ExternalSymbolData[i]); - for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) - WriteNlist(UndefinedSymbolData[i]); - - // Write the string table. - OS << StringTable.str(); - } - } -}; - /* *** */ MCFragment::MCFragment() : Kind(FragmentType(~0)) { diff --git a/lib/MC/MCObjectWriter.cpp b/lib/MC/MCObjectWriter.cpp index ab85e31abb0..d117e82b8a1 100644 --- a/lib/MC/MCObjectWriter.cpp +++ b/lib/MC/MCObjectWriter.cpp @@ -1,4 +1,4 @@ -//===- lib/MC/MCObjetWriter.cpp - MCObjetWriter implementation ------------===// +//===- lib/MC/MCObjectWriter.cpp - MCObjectWriter implementation ----------===// // // The LLVM Compiler Infrastructure // diff --git a/lib/MC/MachObjectWriter.cpp b/lib/MC/MachObjectWriter.cpp new file mode 100644 index 00000000000..4b0077efb0c --- /dev/null +++ b/lib/MC/MachObjectWriter.cpp @@ -0,0 +1,897 @@ +//===- lib/MC/MachObjectWriter.cpp - Mach-O File Writer -------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#include "llvm/MC/MachObjectWriter.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/ADT/Twine.h" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCExpr.h" +#include "llvm/MC/MCObjectWriter.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/MC/MCSymbol.h" +#include "llvm/MC/MCValue.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/MachO.h" +#include "llvm/Target/TargetAsmBackend.h" + +// FIXME: Gross. +#include "../Target/X86/X86FixupKinds.h" + +#include +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 FK_Data_2: return 1; + case X86::reloc_pcrel_4byte: + case X86::reloc_riprel_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_4byte: + case X86::reloc_riprel_4byte: + return true; + } +} + +namespace { + +class MachObjectWriterImpl { + // See . + 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 + }; + + // See . + 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 + // . 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(); + } + }; + + /// @name Relocation Data + /// @{ + + struct MachRelocationEntry { + uint32_t Word0; + uint32_t Word1; + }; + + llvm::DenseMap > Relocations; + + /// @} + /// @name Symbol Table Data + /// @{ + + SmallString<256> StringTable; + std::vector LocalSymbolData; + std::vector ExternalSymbolData; + std::vector 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; + + // struct mach_header (28 bytes) or + // struct mach_header_64 (32 bytes) + + uint64_t Start = OS.tell(); + (void) Start; + + Write32(Is64Bit ? Header_Magic64 : Header_Magic32); + + // FIXME: Support cputype. + Write32(Is64Bit ? MachO::CPUTypeX86_64 : MachO::CPUTypeI386); + // FIXME: Support cpusubtype. + Write32(MachO::CPUSubType_I386_ALL); + Write32(HFT_Object); + Write32(NumLoadCommands); // Object files have a single load command, the + // segment. + Write32(LoadCommandsSize); + Write32(Flags); + if (Is64Bit) + Write32(0); // reserved + + assert(OS.tell() - Start == Is64Bit ? Header64Size : Header32Size); + } + + /// WriteSegmentLoadCommand - Write a segment load command. + /// + /// \arg NumSections - The number of sections in this segment. + /// \arg SectionDataSize - The total size of the sections. + void WriteSegmentLoadCommand(unsigned NumSections, + uint64_t VMSize, + uint64_t SectionDataStartOffset, + uint64_t SectionDataSize) { + // struct segment_command (56 bytes) or + // struct segment_command_64 (72 bytes) + + 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); // vmaddr + Write64(VMSize); // vmsize + Write64(SectionDataStartOffset); // file offset + Write64(SectionDataSize); // file size + } else { + Write32(0); // vmaddr + Write32(VMSize); // vmsize + Write32(SectionDataStartOffset); // file offset + Write32(SectionDataSize); // file size + } + Write32(0x7); // maxprot + Write32(0x7); // initprot + Write32(NumSections); + Write32(0); // flags + + assert(OS.tell() - Start == SegmentLoadCommandSize); + } + + void WriteSection(const MCAssembler &Asm, const MCSectionData &SD, + uint64_t FileOffset, uint64_t RelocationsStart, + unsigned NumRelocations) { + // The offset is unused for virtual sections. + if (Asm.getBackend().isVirtualSection(SD.getSection())) { + assert(SD.getFileSize() == 0 && "Invalid file size!"); + FileOffset = 0; + } + + // struct section (68 bytes) or + // struct section_64 (80 bytes) + + uint64_t Start = OS.tell(); + (void) Start; + + // FIXME: cast<> support! + const MCSectionMachO &Section = + static_cast(SD.getSection()); + WriteBytes(Section.getSectionName(), 16); + WriteBytes(Section.getSegmentName(), 16); + if (Is64Bit) { + Write64(SD.getAddress()); // address + Write64(SD.getSize()); // size + } else { + Write32(SD.getAddress()); // address + Write32(SD.getSize()); // size + } + 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(0); // reserved1 + Write32(Section.getStubSize()); // reserved2 + if (Is64Bit) + Write32(0); // reserved3 + + assert(OS.tell() - Start == Is64Bit ? Section64Size : 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 WriteNlist(MachSymbolData &MSD) { + MCSymbolData &Data = *MSD.SymbolData; + const MCSymbol &Symbol = Data.getSymbol(); + uint8_t Type = 0; + uint16_t Flags = Data.getFlags(); + uint32_t Address = 0; + + // Set the N_TYPE bits. See . + // + // 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.getAddress(); + } + } 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); + if (Is64Bit) + Write64(Address); + else + Write32(Address); + } + + void RecordScatteredRelocation(const MCAssembler &Asm, + const MCFragment &Fragment, + const MCAsmFixup &Fixup, MCValue Target, + uint64_t &FixedValue) { + uint32_t Address = Fragment.getOffset() + Fixup.Offset; + unsigned IsPCRel = isFixupKindPCRel(Fixup.Kind); + unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind); + unsigned Type = RIT_Vanilla; + + // See . + const MCSymbol *A = &Target.getSymA()->getSymbol(); + MCSymbolData *A_SD = &Asm.getSymbolData(*A); + + if (!A_SD->getFragment()) + llvm_report_error("symbol '" + A->getName() + + "' can not be undefined in a subtraction expression"); + + uint32_t Value = A_SD->getAddress(); + uint32_t Value2 = 0; + + if (const MCSymbolRefExpr *B = Target.getSymB()) { + MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol()); + + if (!B_SD->getFragment()) + llvm_report_error("symbol '" + B->getSymbol().getName() + + "' can not be undefined in a subtraction expression"); + + // Select the appropriate difference relocation type. + // + // Note that there is no longer any semantic difference between these two + // relocation types from the linkers point of view, this is done solely + // for pedantic compatibility with 'as'. + Type = A_SD->isExternal() ? RIT_Difference : RIT_LocalDifference; + Value2 = B_SD->getAddress(); + } + + // Relocations are written out in reverse order, so the PAIR comes first. + 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 = ((Address << 0) | + (Type << 24) | + (Log2Size << 28) | + (IsPCRel << 30) | + RF_Scattered); + MRE.Word1 = Value; + Relocations[Fragment.getParent()].push_back(MRE); + } + + virtual void RecordRelocation(const MCAssembler &Asm, + const MCDataFragment &Fragment, + const MCAsmFixup &Fixup, MCValue Target, + uint64_t &FixedValue) { + unsigned IsPCRel = isFixupKindPCRel(Fixup.Kind); + unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind); + + // If this is a difference or a defined symbol plus an offset, then we need + // a scattered relocation entry. + uint32_t Offset = Target.getConstant(); + if (IsPCRel) + Offset += 1 << Log2Size; + if (Target.getSymB() || + (Target.getSymA() && !Target.getSymA()->getSymbol().isUndefined() && + Offset)) { + RecordScatteredRelocation(Asm, Fragment, Fixup, Target, FixedValue); + return; + } + + // See . + uint32_t Address = Fragment.getOffset() + Fixup.Offset; + uint32_t Value = 0; + unsigned Index = 0; + unsigned IsExtern = 0; + unsigned Type = 0; + + if (Target.isAbsolute()) { // constant + // SymbolNum of 0 indicates the absolute section. + // + // FIXME: Currently, these are never generated (see code below). I cannot + // find a case where they are actually emitted. + Type = RIT_Vanilla; + Value = 0; + } else { + const MCSymbol *Symbol = &Target.getSymA()->getSymbol(); + MCSymbolData *SD = &Asm.getSymbolData(*Symbol); + + if (Symbol->isUndefined()) { + IsExtern = 1; + Index = SD->getIndex(); + Value = 0; + } else { + // The index is the section ordinal. + // + // FIXME: O(N) + Index = 1; + MCAssembler::const_iterator it = Asm.begin(), ie = Asm.end(); + for (; it != ie; ++it, ++Index) + if (&*it == SD->getFragment()->getParent()) + break; + assert(it != ie && "Unable to find section index!"); + Value = SD->getAddress(); + } + + Type = RIT_Vanilla; + } + + // struct relocation_info (8 bytes) + MachRelocationEntry MRE; + MRE.Word0 = Address; + MRE.Word1 = ((Index << 0) | + (IsPCRel << 24) | + (Log2Size << 25) | + (IsExtern << 27) | + (Type << 28)); + Relocations[Fragment.getParent()].push_back(MRE); + } + + void BindIndirectSymbols(MCAssembler &Asm) { + // 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(it->SectionData->getSection()); + + if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) + continue; + + Asm.getOrCreateSymbolData(*it->Symbol); + } + + // 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(it->SectionData->getSection()); + + if (Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS && + Section.getType() != MCSectionMachO::S_SYMBOL_STUBS) + continue; + + // Set the symbol type to undefined lazy, but only on construction. + // + // FIXME: Do not hardcode. + bool Created; + MCSymbolData &Entry = Asm.getOrCreateSymbolData(*it->Symbol, &Created); + if (Created) + 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 &LocalSymbolData, + std::vector &ExternalSymbolData, + std::vector &UndefinedSymbolData) { + // Build section lookup table. + DenseMap 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 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) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(it)) + 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) { + const MCSymbol &Symbol = it->getSymbol(); + + // Ignore non-linker visible symbols. + if (!Asm.isSymbolLinkerVisible(it)) + 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. + while (StringTable.size() % 4) + StringTable += '\x00'; + } + + virtual void ExecutePostLayoutBinding(MCAssembler &Asm) { + // Create symbol data for any indirect symbols. + BindIndirectSymbols(Asm); + + // Compute symbol table information and bind symbol indices. + ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData, + UndefinedSymbolData); + } + + virtual void WriteObject(const MCAssembler &Asm) { + unsigned NumSections = Asm.size(); + + // The section data starts after the header, the segment load command (and + // section headers) and the symbol table. + unsigned NumLoadCommands = 1; + uint64_t LoadCommandsSize = Is64Bit ? + SegmentLoadCommand64Size + NumSections * Section64Size : + SegmentLoadCommand32Size + NumSections * Section32Size; + + // Add the symbol table load command sizes, if used. + unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() + + UndefinedSymbolData.size(); + 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 = (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; + + VMSize = std::max(VMSize, SD.getAddress() + SD.getSize()); + + if (Asm.getBackend().isVirtualSection(SD.getSection())) + continue; + + SectionDataSize = std::max(SectionDataSize, + SD.getAddress() + SD.getSize()); + SectionDataFileSize = std::max(SectionDataFileSize, + SD.getAddress() + SD.getFileSize()); + } + + // The section data is padded 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... + WriteHeader(NumLoadCommands, LoadCommandsSize, + Asm.getSubsectionsViaSymbols()); + WriteSegmentLoadCommand(NumSections, VMSize, + SectionDataStart, SectionDataSize); + + // ... and then the section headers. + uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize; + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + std::vector &Relocs = Relocations[it]; + unsigned NumRelocs = Relocs.size(); + uint64_t SectionStart = SectionDataStart + it->getAddress(); + WriteSection(Asm, *it, 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 * (Is64Bit ? Nlist64Size : + Nlist32Size); + WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols, + StringTableOffset, StringTable.size()); + + WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols, + FirstExternalSymbol, NumExternalSymbols, + FirstUndefinedSymbol, NumUndefinedSymbols, + IndirectSymbolOffset, NumIndirectSymbols); + } + + // Write the actual section data. + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) + Asm.WriteSectionData(it, Writer); + + // Write the extra padding. + WriteZeros(SectionDataPadding); + + // Write the relocation entries. + for (MCAssembler::const_iterator it = Asm.begin(), + ie = Asm.end(); it != ie; ++it) { + // Write the section relocation entries, in reverse order to match 'as' + // (approximately, the exact algorithm is more complicated than this). + std::vector &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); + } + } + + // Write the symbol table data, if used. + if (NumSymbols) { + // Write the indirect symbol entries. + for (MCAssembler::const_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(it->SectionData->getSection()); + if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) { + // If this symbol is defined and internal, mark it as such. + 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()); + } + + // FIXME: Check that offsets match computed ones. + + // Write the symbol table entries. + for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i) + WriteNlist(LocalSymbolData[i]); + for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i) + WriteNlist(ExternalSymbolData[i]); + for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i) + WriteNlist(UndefinedSymbolData[i]); + + // Write the string table. + 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 MCDataFragment &Fragment, + const MCAsmFixup &Fixup, MCValue Target, + uint64_t &FixedValue) { + ((MachObjectWriterImpl*) Impl)->RecordRelocation(Asm, Fragment, Fixup, + Target, FixedValue); +} + +void MachObjectWriter::WriteObject(const MCAssembler &Asm) { + ((MachObjectWriterImpl*) Impl)->WriteObject(Asm); +} -- 2.34.1