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author | rdivacky <rdivacky@FreeBSD.org> | 2009-10-14 17:57:32 +0000 |
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committer | rdivacky <rdivacky@FreeBSD.org> | 2009-10-14 17:57:32 +0000 |
commit | cd749a9c07f1de2fb8affde90537efa4bc3e7c54 (patch) | |
tree | b21f6de4e08b89bb7931806bab798fc2a5e3a686 /lib/MC/MCAssembler.cpp | |
parent | 72621d11de5b873f1695f391eb95f0b336c3d2d4 (diff) | |
download | FreeBSD-src-cd749a9c07f1de2fb8affde90537efa4bc3e7c54.zip FreeBSD-src-cd749a9c07f1de2fb8affde90537efa4bc3e7c54.tar.gz |
Update llvm to r84119.
Diffstat (limited to 'lib/MC/MCAssembler.cpp')
-rw-r--r-- | lib/MC/MCAssembler.cpp | 1190 |
1 files changed, 1190 insertions, 0 deletions
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp new file mode 100644 index 0000000..0afdf98 --- /dev/null +++ b/lib/MC/MCAssembler.cpp @@ -0,0 +1,1190 @@ +//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "assembler" +#include "llvm/MC/MCAssembler.h" +#include "llvm/MC/MCSectionMachO.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; + +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>. + enum { + Header_Magic32 = 0xFEEDFACE, + Header_Magic64 = 0xFEEDFACF + }; + + static const unsigned Header32Size = 28; + 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_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; + bool IsLSB; + +public: + MachObjectWriter(raw_ostream &_OS, bool _IsLSB = true) + : OS(_OS), IsLSB(_IsLSB) { + } + + /// @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) { + Write16(uint16_t(Value >> 0)); + Write16(uint16_t(Value >> 16)); + } else { + 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)); + } + } + + void WriteZeros(unsigned N) { + const char Zeros[16] = { 0 }; + + for (unsigned i = 0, e = N / 16; i != e; ++i) + OS << StringRef(Zeros, 16); + + OS << StringRef(Zeros, N % 16); + } + + void WriteString(const StringRef &Str, unsigned ZeroFillSize = 0) { + OS << Str; + if (ZeroFillSize) + WriteZeros(ZeroFillSize - Str.size()); + } + + /// @} + + void WriteHeader32(unsigned NumLoadCommands, unsigned LoadCommandsSize, + bool SubsectionsViaSymbols) { + uint32_t Flags = 0; + + if (SubsectionsViaSymbols) + Flags |= HF_SubsectionsViaSymbols; + + // struct mach_header (28 bytes) + + uint64_t Start = OS.tell(); + (void) Start; + + Write32(Header_Magic32); + + // FIXME: Support cputype. + Write32(TargetMachOWriterInfo::HDR_CPU_TYPE_I386); + // FIXME: Support cpusubtype. + Write32(TargetMachOWriterInfo::HDR_CPU_SUBTYPE_I386_ALL); + Write32(HFT_Object); + Write32(NumLoadCommands); // Object files have a single load command, the + // segment. + Write32(LoadCommandsSize); + Write32(Flags); + + assert(OS.tell() - Start == Header32Size); + } + + /// 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(); + (void) Start; + + Write32(LCT_Segment); + Write32(SegmentLoadCommand32Size + NumSections * Section32Size); + + WriteString("", 16); + 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 == SegmentLoadCommand32Size); + } + + 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(); + (void) Start; + + // FIXME: cast<> support! + const MCSectionMachO &Section = + static_cast<const MCSectionMachO&>(SD.getSection()); + WriteString(Section.getSectionName(), 16); + WriteString(Section.getSegmentName(), 16); + Write32(SD.getAddress()); // address + Write32(SD.getSize()); // size + Write32(FileOffset); + + assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!"); + Write32(Log2_32(SD.getAlignment())); + 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; + const 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) { + const 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) { + const 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() : Kind(FragmentType(~0)) { +} + +MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent) + : Kind(_Kind), + Parent(_Parent), + FileSize(~UINT64_C(0)) +{ + 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(0) {} + +MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A) + : Section(&_Section), + Alignment(1), + Address(~UINT64_C(0)), + Size(~UINT64_C(0)), + FileSize(~UINT64_C(0)), + LastFixupLookup(~0) +{ + if (A) + A->getSectionList().push_back(this); +} + +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(0) {} + +MCSymbolData::MCSymbolData(const 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(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() { + // Layout the concrete sections and fragments. + uint64_t Address = 0; + MCSectionData *Prev = 0; + for (iterator it = begin(), ie = end(); it != ie; ++it) { + 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; + } + + // Layout the virtual sections. + for (iterator it = begin(), ie = end(); it != ie; ++it) { + MCSectionData &SD = *it; + + if (!isVirtualSection(SD.getSection())) + continue; + + SD.setAddress(Address); + LayoutSection(SD); + Address += SD.getSize(); + } + + // Write the object file. + MachObjectWriter MOW(OS); + MOW.WriteObject(*this); + + OS.flush(); +} |