//===-- MachOWriter.cpp - Target-independent Mach-O Writer code -----------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the target-independent Mach-O writer. This file writes // out the Mach-O file in the following order: // // #1 FatHeader (universal-only) // #2 FatArch (universal-only, 1 per universal arch) // Per arch: // #3 Header // #4 Load Commands // #5 Sections // #6 Relocations // #7 Symbols // #8 Strings // //===----------------------------------------------------------------------===// #include "MachOWriter.h" #include "llvm/Constants.h" #include "llvm/DerivedTypes.h" #include "llvm/Module.h" #include "llvm/PassManager.h" #include "llvm/CodeGen/FileWriters.h" #include "llvm/CodeGen/MachineCodeEmitter.h" #include "llvm/CodeGen/MachineConstantPool.h" #include "llvm/CodeGen/MachineJumpTableInfo.h" #include "llvm/Target/TargetAsmInfo.h" #include "llvm/Target/TargetJITInfo.h" #include "llvm/Support/Mangler.h" #include "llvm/Support/MathExtras.h" #include "llvm/Support/OutputBuffer.h" #include "llvm/Support/Streams.h" #include "llvm/Support/raw_ostream.h" #include #include using namespace llvm; /// AddMachOWriter - Concrete function to add the Mach-O writer to the function /// pass manager. MachineCodeEmitter *llvm::AddMachOWriter(PassManagerBase &PM, raw_ostream &O, TargetMachine &TM) { MachOWriter *MOW = new MachOWriter(O, TM); PM.add(MOW); return &MOW->getMachineCodeEmitter(); } //===----------------------------------------------------------------------===// // MachOCodeEmitter Implementation //===----------------------------------------------------------------------===// namespace llvm { /// MachOCodeEmitter - This class is used by the MachOWriter to emit the code /// for functions to the Mach-O file. class MachOCodeEmitter : public MachineCodeEmitter { MachOWriter &MOW; /// Target machine description. TargetMachine &TM; /// is64Bit/isLittleEndian - This information is inferred from the target /// machine directly, indicating what header values and flags to set. bool is64Bit, isLittleEndian; /// Relocations - These are the relocations that the function needs, as /// emitted. std::vector Relocations; /// CPLocations - This is a map of constant pool indices to offsets from the /// start of the section for that constant pool index. std::vector CPLocations; /// CPSections - This is a map of constant pool indices to the MachOSection /// containing the constant pool entry for that index. std::vector CPSections; /// JTLocations - This is a map of jump table indices to offsets from the /// start of the section for that jump table index. std::vector JTLocations; /// MBBLocations - This vector is a mapping from MBB ID's to their address. /// It is filled in by the StartMachineBasicBlock callback and queried by /// the getMachineBasicBlockAddress callback. std::vector MBBLocations; public: MachOCodeEmitter(MachOWriter &mow) : MOW(mow), TM(MOW.TM) { is64Bit = TM.getTargetData()->getPointerSizeInBits() == 64; isLittleEndian = TM.getTargetData()->isLittleEndian(); } virtual void startFunction(MachineFunction &MF); virtual bool finishFunction(MachineFunction &MF); virtual void addRelocation(const MachineRelocation &MR) { Relocations.push_back(MR); } void emitConstantPool(MachineConstantPool *MCP); void emitJumpTables(MachineJumpTableInfo *MJTI); virtual uintptr_t getConstantPoolEntryAddress(unsigned Index) const { assert(CPLocations.size() > Index && "CP not emitted!"); return CPLocations[Index]; } virtual uintptr_t getJumpTableEntryAddress(unsigned Index) const { assert(JTLocations.size() > Index && "JT not emitted!"); return JTLocations[Index]; } virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) { if (MBBLocations.size() <= (unsigned)MBB->getNumber()) MBBLocations.resize((MBB->getNumber()+1)*2); MBBLocations[MBB->getNumber()] = getCurrentPCOffset(); } virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const { assert(MBBLocations.size() > (unsigned)MBB->getNumber() && MBBLocations[MBB->getNumber()] && "MBB not emitted!"); return MBBLocations[MBB->getNumber()]; } virtual uintptr_t getLabelAddress(uint64_t Label) const { assert(0 && "get Label not implemented"); abort(); return 0; } virtual void emitLabel(uint64_t LabelID) { assert(0 && "emit Label not implemented"); abort(); } virtual void setModuleInfo(llvm::MachineModuleInfo* MMI) { } /// JIT SPECIFIC FUNCTIONS - DO NOT IMPLEMENT THESE HERE! virtual void startGVStub(const GlobalValue* F, unsigned StubSize, unsigned Alignment = 1) { assert(0 && "JIT specific function called!"); abort(); } virtual void *finishGVStub(const GlobalValue* F) { assert(0 && "JIT specific function called!"); abort(); return 0; } }; } /// startFunction - This callback is invoked when a new machine function is /// about to be emitted. void MachOCodeEmitter::startFunction(MachineFunction &MF) { const TargetData *TD = TM.getTargetData(); const Function *F = MF.getFunction(); // Align the output buffer to the appropriate alignment, power of 2. unsigned FnAlign = F->getAlignment(); unsigned TDAlign = TD->getPrefTypeAlignment(F->getType()); unsigned Align = Log2_32(std::max(FnAlign, TDAlign)); assert(!(Align & (Align-1)) && "Alignment is not a power of two!"); // Get the Mach-O Section that this function belongs in. MachOWriter::MachOSection *MOS = MOW.getTextSection(); // FIXME: better memory management MOS->SectionData.reserve(4096); BufferBegin = &MOS->SectionData[0]; BufferEnd = BufferBegin + MOS->SectionData.capacity(); // Upgrade the section alignment if required. if (MOS->align < Align) MOS->align = Align; // Round the size up to the correct alignment for starting the new function. if ((MOS->size & ((1 << Align) - 1)) != 0) { MOS->size += (1 << Align); MOS->size &= ~((1 << Align) - 1); } // FIXME: Using MOS->size directly here instead of calculating it from the // output buffer size (impossible because the code emitter deals only in raw // bytes) forces us to manually synchronize size and write padding zero bytes // to the output buffer for all non-text sections. For text sections, we do // not synchonize the output buffer, and we just blow up if anyone tries to // write non-code to it. An assert should probably be added to // AddSymbolToSection to prevent calling it on the text section. CurBufferPtr = BufferBegin + MOS->size; // Clear per-function data structures. CPLocations.clear(); CPSections.clear(); JTLocations.clear(); MBBLocations.clear(); } /// finishFunction - This callback is invoked after the function is completely /// finished. bool MachOCodeEmitter::finishFunction(MachineFunction &MF) { // Get the Mach-O Section that this function belongs in. MachOWriter::MachOSection *MOS = MOW.getTextSection(); // Get a symbol for the function to add to the symbol table // FIXME: it seems like we should call something like AddSymbolToSection // in startFunction rather than changing the section size and symbol n_value // here. const GlobalValue *FuncV = MF.getFunction(); MachOSym FnSym(FuncV, MOW.Mang->getValueName(FuncV), MOS->Index, TM); FnSym.n_value = MOS->size; MOS->size = CurBufferPtr - BufferBegin; // Emit constant pool to appropriate section(s) emitConstantPool(MF.getConstantPool()); // Emit jump tables to appropriate section emitJumpTables(MF.getJumpTableInfo()); // If we have emitted any relocations to function-specific objects such as // basic blocks, constant pools entries, or jump tables, record their // addresses now so that we can rewrite them with the correct addresses // later. for (unsigned i = 0, e = Relocations.size(); i != e; ++i) { MachineRelocation &MR = Relocations[i]; intptr_t Addr; if (MR.isBasicBlock()) { Addr = getMachineBasicBlockAddress(MR.getBasicBlock()); MR.setConstantVal(MOS->Index); MR.setResultPointer((void*)Addr); } else if (MR.isJumpTableIndex()) { Addr = getJumpTableEntryAddress(MR.getJumpTableIndex()); MR.setConstantVal(MOW.getJumpTableSection()->Index); MR.setResultPointer((void*)Addr); } else if (MR.isConstantPoolIndex()) { Addr = getConstantPoolEntryAddress(MR.getConstantPoolIndex()); MR.setConstantVal(CPSections[MR.getConstantPoolIndex()]); MR.setResultPointer((void*)Addr); } else if (MR.isGlobalValue()) { // FIXME: This should be a set or something that uniques MOW.PendingGlobals.push_back(MR.getGlobalValue()); } else { assert(0 && "Unhandled relocation type"); } MOS->Relocations.push_back(MR); } Relocations.clear(); // Finally, add it to the symtab. MOW.SymbolTable.push_back(FnSym); return false; } /// emitConstantPool - For each constant pool entry, figure out which section /// the constant should live in, allocate space for it, and emit it to the /// Section data buffer. void MachOCodeEmitter::emitConstantPool(MachineConstantPool *MCP) { const std::vector &CP = MCP->getConstants(); if (CP.empty()) return; // FIXME: handle PIC codegen assert(TM.getRelocationModel() != Reloc::PIC_ && "PIC codegen not yet handled for mach-o jump tables!"); // Although there is no strict necessity that I am aware of, we will do what // gcc for OS X does and put each constant pool entry in a section of constant // objects of a certain size. That means that float constants go in the // literal4 section, and double objects go in literal8, etc. // // FIXME: revisit this decision if we ever do the "stick everything into one // "giant object for PIC" optimization. for (unsigned i = 0, e = CP.size(); i != e; ++i) { const Type *Ty = CP[i].getType(); unsigned Size = TM.getTargetData()->getTypePaddedSize(Ty); MachOWriter::MachOSection *Sec = MOW.getConstSection(CP[i].Val.ConstVal); OutputBuffer SecDataOut(Sec->SectionData, is64Bit, isLittleEndian); CPLocations.push_back(Sec->SectionData.size()); CPSections.push_back(Sec->Index); // FIXME: remove when we have unified size + output buffer Sec->size += Size; // Allocate space in the section for the global. // FIXME: need alignment? // FIXME: share between here and AddSymbolToSection? for (unsigned j = 0; j < Size; ++j) SecDataOut.outbyte(0); MOW.InitMem(CP[i].Val.ConstVal, &Sec->SectionData[0], CPLocations[i], TM.getTargetData(), Sec->Relocations); } } /// emitJumpTables - Emit all the jump tables for a given jump table info /// record to the appropriate section. void MachOCodeEmitter::emitJumpTables(MachineJumpTableInfo *MJTI) { const std::vector &JT = MJTI->getJumpTables(); if (JT.empty()) return; // FIXME: handle PIC codegen assert(TM.getRelocationModel() != Reloc::PIC_ && "PIC codegen not yet handled for mach-o jump tables!"); MachOWriter::MachOSection *Sec = MOW.getJumpTableSection(); unsigned TextSecIndex = MOW.getTextSection()->Index; OutputBuffer SecDataOut(Sec->SectionData, is64Bit, isLittleEndian); for (unsigned i = 0, e = JT.size(); i != e; ++i) { // For each jump table, record its offset from the start of the section, // reserve space for the relocations to the MBBs, and add the relocations. const std::vector &MBBs = JT[i].MBBs; JTLocations.push_back(Sec->SectionData.size()); for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) { MachineRelocation MR(MOW.GetJTRelocation(Sec->SectionData.size(), MBBs[mi])); MR.setResultPointer((void *)JTLocations[i]); MR.setConstantVal(TextSecIndex); Sec->Relocations.push_back(MR); SecDataOut.outaddr(0); } } // FIXME: remove when we have unified size + output buffer Sec->size = Sec->SectionData.size(); } //===----------------------------------------------------------------------===// // MachOWriter Implementation //===----------------------------------------------------------------------===// char MachOWriter::ID = 0; MachOWriter::MachOWriter(raw_ostream &o, TargetMachine &tm) : MachineFunctionPass(&ID), O(o), TM(tm) { is64Bit = TM.getTargetData()->getPointerSizeInBits() == 64; isLittleEndian = TM.getTargetData()->isLittleEndian(); // Create the machine code emitter object for this target. MCE = new MachOCodeEmitter(*this); } MachOWriter::~MachOWriter() { delete MCE; } void MachOWriter::AddSymbolToSection(MachOSection *Sec, GlobalVariable *GV) { const Type *Ty = GV->getType()->getElementType(); unsigned Size = TM.getTargetData()->getTypePaddedSize(Ty); unsigned Align = TM.getTargetData()->getPreferredAlignment(GV); // Reserve space in the .bss section for this symbol while maintaining the // desired section alignment, which must be at least as much as required by // this symbol. OutputBuffer SecDataOut(Sec->SectionData, is64Bit, isLittleEndian); if (Align) { uint64_t OrigSize = Sec->size; Align = Log2_32(Align); Sec->align = std::max(unsigned(Sec->align), Align); Sec->size = (Sec->size + Align - 1) & ~(Align-1); // Add alignment padding to buffer as well. // FIXME: remove when we have unified size + output buffer unsigned AlignedSize = Sec->size - OrigSize; for (unsigned i = 0; i < AlignedSize; ++i) SecDataOut.outbyte(0); } // Globals without external linkage apparently do not go in the symbol table. if (GV->getLinkage() != GlobalValue::InternalLinkage) { MachOSym Sym(GV, Mang->getValueName(GV), Sec->Index, TM); Sym.n_value = Sec->size; SymbolTable.push_back(Sym); } // Record the offset of the symbol, and then allocate space for it. // FIXME: remove when we have unified size + output buffer Sec->size += Size; // Now that we know what section the GlovalVariable is going to be emitted // into, update our mappings. // FIXME: We may also need to update this when outputting non-GlobalVariable // GlobalValues such as functions. GVSection[GV] = Sec; GVOffset[GV] = Sec->SectionData.size(); // Allocate space in the section for the global. for (unsigned i = 0; i < Size; ++i) SecDataOut.outbyte(0); } void MachOWriter::EmitGlobal(GlobalVariable *GV) { const Type *Ty = GV->getType()->getElementType(); unsigned Size = TM.getTargetData()->getTypePaddedSize(Ty); bool NoInit = !GV->hasInitializer(); // If this global has a zero initializer, it is part of the .bss or common // section. if (NoInit || GV->getInitializer()->isNullValue()) { // If this global is part of the common block, add it now. Variables are // part of the common block if they are zero initialized and allowed to be // merged with other symbols. if (NoInit || GV->hasLinkOnceLinkage() || GV->hasWeakLinkage() || GV->hasCommonLinkage()) { MachOSym ExtOrCommonSym(GV, Mang->getValueName(GV), MachOSym::NO_SECT,TM); // For undefined (N_UNDF) external (N_EXT) types, n_value is the size in // bytes of the symbol. ExtOrCommonSym.n_value = Size; SymbolTable.push_back(ExtOrCommonSym); // Remember that we've seen this symbol GVOffset[GV] = Size; return; } // Otherwise, this symbol is part of the .bss section. MachOSection *BSS = getBSSSection(); AddSymbolToSection(BSS, GV); return; } // Scalar read-only data goes in a literal section if the scalar is 4, 8, or // 16 bytes, or a cstring. Other read only data goes into a regular const // section. Read-write data goes in the data section. MachOSection *Sec = GV->isConstant() ? getConstSection(GV->getInitializer()) : getDataSection(); AddSymbolToSection(Sec, GV); InitMem(GV->getInitializer(), &Sec->SectionData[0], GVOffset[GV], TM.getTargetData(), Sec->Relocations); } bool MachOWriter::runOnMachineFunction(MachineFunction &MF) { // Nothing to do here, this is all done through the MCE object. return false; } bool MachOWriter::doInitialization(Module &M) { // Set the magic value, now that we know the pointer size and endianness Header.setMagic(isLittleEndian, is64Bit); // Set the file type // FIXME: this only works for object files, we do not support the creation // of dynamic libraries or executables at this time. Header.filetype = MachOHeader::MH_OBJECT; Mang = new Mangler(M); return false; } /// doFinalization - Now that the module has been completely processed, emit /// the Mach-O file to 'O'. bool MachOWriter::doFinalization(Module &M) { // FIXME: we don't handle debug info yet, we should probably do that. // Okay, the.text section has been completed, build the .data, .bss, and // "common" sections next. for (Module::global_iterator I = M.global_begin(), E = M.global_end(); I != E; ++I) EmitGlobal(I); // Emit the header and load commands. EmitHeaderAndLoadCommands(); // Emit the various sections and their relocation info. EmitSections(); // Write the symbol table and the string table to the end of the file. O.write((char*)&SymT[0], SymT.size()); O.write((char*)&StrT[0], StrT.size()); // We are done with the abstract symbols. SectionList.clear(); SymbolTable.clear(); DynamicSymbolTable.clear(); // Release the name mangler object. delete Mang; Mang = 0; return false; } void MachOWriter::EmitHeaderAndLoadCommands() { // Step #0: Fill in the segment load command size, since we need it to figure // out the rest of the header fields MachOSegment SEG("", is64Bit); SEG.nsects = SectionList.size(); SEG.cmdsize = SEG.cmdSize(is64Bit) + SEG.nsects * SectionList[0]->cmdSize(is64Bit); // Step #1: calculate the number of load commands. We always have at least // one, for the LC_SEGMENT load command, plus two for the normal // and dynamic symbol tables, if there are any symbols. Header.ncmds = SymbolTable.empty() ? 1 : 3; // Step #2: calculate the size of the load commands Header.sizeofcmds = SEG.cmdsize; if (!SymbolTable.empty()) Header.sizeofcmds += SymTab.cmdsize + DySymTab.cmdsize; // Step #3: write the header to the file // Local alias to shortenify coming code. DataBuffer &FH = Header.HeaderData; OutputBuffer FHOut(FH, is64Bit, isLittleEndian); FHOut.outword(Header.magic); FHOut.outword(TM.getMachOWriterInfo()->getCPUType()); FHOut.outword(TM.getMachOWriterInfo()->getCPUSubType()); FHOut.outword(Header.filetype); FHOut.outword(Header.ncmds); FHOut.outword(Header.sizeofcmds); FHOut.outword(Header.flags); if (is64Bit) FHOut.outword(Header.reserved); // Step #4: Finish filling in the segment load command and write it out for (std::vector::iterator I = SectionList.begin(), E = SectionList.end(); I != E; ++I) SEG.filesize += (*I)->size; SEG.vmsize = SEG.filesize; SEG.fileoff = Header.cmdSize(is64Bit) + Header.sizeofcmds; FHOut.outword(SEG.cmd); FHOut.outword(SEG.cmdsize); FHOut.outstring(SEG.segname, 16); FHOut.outaddr(SEG.vmaddr); FHOut.outaddr(SEG.vmsize); FHOut.outaddr(SEG.fileoff); FHOut.outaddr(SEG.filesize); FHOut.outword(SEG.maxprot); FHOut.outword(SEG.initprot); FHOut.outword(SEG.nsects); FHOut.outword(SEG.flags); // Step #5: Finish filling in the fields of the MachOSections uint64_t currentAddr = 0; for (std::vector::iterator I = SectionList.begin(), E = SectionList.end(); I != E; ++I) { MachOSection *MOS = *I; MOS->addr = currentAddr; MOS->offset = currentAddr + SEG.fileoff; // FIXME: do we need to do something with alignment here? currentAddr += MOS->size; } // Step #6: Emit the symbol table to temporary buffers, so that we know the // size of the string table when we write the next load command. This also // sorts and assigns indices to each of the symbols, which is necessary for // emitting relocations to externally-defined objects. BufferSymbolAndStringTable(); // Step #7: Calculate the number of relocations for each section and write out // the section commands for each section currentAddr += SEG.fileoff; for (std::vector::iterator I = SectionList.begin(), E = SectionList.end(); I != E; ++I) { MachOSection *MOS = *I; // Convert the relocations to target-specific relocations, and fill in the // relocation offset for this section. CalculateRelocations(*MOS); MOS->reloff = MOS->nreloc ? currentAddr : 0; currentAddr += MOS->nreloc * 8; // write the finalized section command to the output buffer FHOut.outstring(MOS->sectname, 16); FHOut.outstring(MOS->segname, 16); FHOut.outaddr(MOS->addr); FHOut.outaddr(MOS->size); FHOut.outword(MOS->offset); FHOut.outword(MOS->align); FHOut.outword(MOS->reloff); FHOut.outword(MOS->nreloc); FHOut.outword(MOS->flags); FHOut.outword(MOS->reserved1); FHOut.outword(MOS->reserved2); if (is64Bit) FHOut.outword(MOS->reserved3); } // Step #8: Emit LC_SYMTAB/LC_DYSYMTAB load commands SymTab.symoff = currentAddr; SymTab.nsyms = SymbolTable.size(); SymTab.stroff = SymTab.symoff + SymT.size(); SymTab.strsize = StrT.size(); FHOut.outword(SymTab.cmd); FHOut.outword(SymTab.cmdsize); FHOut.outword(SymTab.symoff); FHOut.outword(SymTab.nsyms); FHOut.outword(SymTab.stroff); FHOut.outword(SymTab.strsize); // FIXME: set DySymTab fields appropriately // We should probably just update these in BufferSymbolAndStringTable since // thats where we're partitioning up the different kinds of symbols. FHOut.outword(DySymTab.cmd); FHOut.outword(DySymTab.cmdsize); FHOut.outword(DySymTab.ilocalsym); FHOut.outword(DySymTab.nlocalsym); FHOut.outword(DySymTab.iextdefsym); FHOut.outword(DySymTab.nextdefsym); FHOut.outword(DySymTab.iundefsym); FHOut.outword(DySymTab.nundefsym); FHOut.outword(DySymTab.tocoff); FHOut.outword(DySymTab.ntoc); FHOut.outword(DySymTab.modtaboff); FHOut.outword(DySymTab.nmodtab); FHOut.outword(DySymTab.extrefsymoff); FHOut.outword(DySymTab.nextrefsyms); FHOut.outword(DySymTab.indirectsymoff); FHOut.outword(DySymTab.nindirectsyms); FHOut.outword(DySymTab.extreloff); FHOut.outword(DySymTab.nextrel); FHOut.outword(DySymTab.locreloff); FHOut.outword(DySymTab.nlocrel); O.write((char*)&FH[0], FH.size()); } /// EmitSections - Now that we have constructed the file header and load /// commands, emit the data for each section to the file. void MachOWriter::EmitSections() { for (std::vector::iterator I = SectionList.begin(), E = SectionList.end(); I != E; ++I) // Emit the contents of each section O.write((char*)&(*I)->SectionData[0], (*I)->size); for (std::vector::iterator I = SectionList.begin(), E = SectionList.end(); I != E; ++I) // Emit the relocation entry data for each section. O.write((char*)&(*I)->RelocBuffer[0], (*I)->RelocBuffer.size()); } /// PartitionByLocal - Simple boolean predicate that returns true if Sym is /// a local symbol rather than an external symbol. bool MachOWriter::PartitionByLocal(const MachOSym &Sym) { return (Sym.n_type & (MachOSym::N_EXT | MachOSym::N_PEXT)) == 0; } /// PartitionByDefined - Simple boolean predicate that returns true if Sym is /// defined in this module. bool MachOWriter::PartitionByDefined(const MachOSym &Sym) { // FIXME: Do N_ABS or N_INDR count as defined? return (Sym.n_type & MachOSym::N_SECT) == MachOSym::N_SECT; } /// BufferSymbolAndStringTable - Sort the symbols we encountered and assign them /// each a string table index so that they appear in the correct order in the /// output file. void MachOWriter::BufferSymbolAndStringTable() { // The order of the symbol table is: // 1. local symbols // 2. defined external symbols (sorted by name) // 3. undefined external symbols (sorted by name) // Before sorting the symbols, check the PendingGlobals for any undefined // globals that need to be put in the symbol table. for (std::vector::iterator I = PendingGlobals.begin(), E = PendingGlobals.end(); I != E; ++I) { if (GVOffset[*I] == 0 && GVSection[*I] == 0) { MachOSym UndfSym(*I, Mang->getValueName(*I), MachOSym::NO_SECT, TM); SymbolTable.push_back(UndfSym); GVOffset[*I] = -1; } } // Sort the symbols by name, so that when we partition the symbols by scope // of definition, we won't have to sort by name within each partition. std::sort(SymbolTable.begin(), SymbolTable.end(), MachOSymCmp()); // Parition the symbol table entries so that all local symbols come before // all symbols with external linkage. { 1 | 2 3 } std::partition(SymbolTable.begin(), SymbolTable.end(), PartitionByLocal); // Advance iterator to beginning of external symbols and partition so that // all external symbols defined in this module come before all external // symbols defined elsewhere. { 1 | 2 | 3 } for (std::vector::iterator I = SymbolTable.begin(), E = SymbolTable.end(); I != E; ++I) { if (!PartitionByLocal(*I)) { std::partition(I, E, PartitionByDefined); break; } } // Calculate the starting index for each of the local, extern defined, and // undefined symbols, as well as the number of each to put in the LC_DYSYMTAB // load command. for (std::vector::iterator I = SymbolTable.begin(), E = SymbolTable.end(); I != E; ++I) { if (PartitionByLocal(*I)) { ++DySymTab.nlocalsym; ++DySymTab.iextdefsym; ++DySymTab.iundefsym; } else if (PartitionByDefined(*I)) { ++DySymTab.nextdefsym; ++DySymTab.iundefsym; } else { ++DySymTab.nundefsym; } } // Write out a leading zero byte when emitting string table, for n_strx == 0 // which means an empty string. OutputBuffer StrTOut(StrT, is64Bit, isLittleEndian); StrTOut.outbyte(0); // The order of the string table is: // 1. strings for external symbols // 2. strings for local symbols // Since this is the opposite order from the symbol table, which we have just // sorted, we can walk the symbol table backwards to output the string table. for (std::vector::reverse_iterator I = SymbolTable.rbegin(), E = SymbolTable.rend(); I != E; ++I) { if (I->GVName == "") { I->n_strx = 0; } else { I->n_strx = StrT.size(); StrTOut.outstring(I->GVName, I->GVName.length()+1); } } OutputBuffer SymTOut(SymT, is64Bit, isLittleEndian); unsigned index = 0; for (std::vector::iterator I = SymbolTable.begin(), E = SymbolTable.end(); I != E; ++I, ++index) { // Add the section base address to the section offset in the n_value field // to calculate the full address. // FIXME: handle symbols where the n_value field is not the address GlobalValue *GV = const_cast(I->GV); if (GV && GVSection[GV]) I->n_value += GVSection[GV]->addr; if (GV && (GVOffset[GV] == -1)) GVOffset[GV] = index; // Emit nlist to buffer SymTOut.outword(I->n_strx); SymTOut.outbyte(I->n_type); SymTOut.outbyte(I->n_sect); SymTOut.outhalf(I->n_desc); SymTOut.outaddr(I->n_value); } } /// CalculateRelocations - For each MachineRelocation in the current section, /// calculate the index of the section containing the object to be relocated, /// and the offset into that section. From this information, create the /// appropriate target-specific MachORelocation type and add buffer it to be /// written out after we are finished writing out sections. void MachOWriter::CalculateRelocations(MachOSection &MOS) { for (unsigned i = 0, e = MOS.Relocations.size(); i != e; ++i) { MachineRelocation &MR = MOS.Relocations[i]; unsigned TargetSection = MR.getConstantVal(); unsigned TargetAddr = 0; unsigned TargetIndex = 0; // This is a scattered relocation entry if it points to a global value with // a non-zero offset. bool Scattered = false; bool Extern = false; // Since we may not have seen the GlobalValue we were interested in yet at // the time we emitted the relocation for it, fix it up now so that it // points to the offset into the correct section. if (MR.isGlobalValue()) { GlobalValue *GV = MR.getGlobalValue(); MachOSection *MOSPtr = GVSection[GV]; intptr_t Offset = GVOffset[GV]; // If we have never seen the global before, it must be to a symbol // defined in another module (N_UNDF). if (!MOSPtr) { // FIXME: need to append stub suffix Extern = true; TargetAddr = 0; TargetIndex = GVOffset[GV]; } else { Scattered = TargetSection != 0; TargetSection = MOSPtr->Index; } MR.setResultPointer((void*)Offset); } // If the symbol is locally defined, pass in the address of the section and // the section index to the code which will generate the target relocation. if (!Extern) { MachOSection &To = *SectionList[TargetSection - 1]; TargetAddr = To.addr; TargetIndex = To.Index; } OutputBuffer RelocOut(MOS.RelocBuffer, is64Bit, isLittleEndian); OutputBuffer SecOut(MOS.SectionData, is64Bit, isLittleEndian); MOS.nreloc += GetTargetRelocation(MR, MOS.Index, TargetAddr, TargetIndex, RelocOut, SecOut, Scattered, Extern); } } // InitMem - Write the value of a Constant to the specified memory location, // converting it into bytes and relocations. void MachOWriter::InitMem(const Constant *C, void *Addr, intptr_t Offset, const TargetData *TD, std::vector &MRs) { typedef std::pair CPair; std::vector WorkList; WorkList.push_back(CPair(C,(intptr_t)Addr + Offset)); intptr_t ScatteredOffset = 0; while (!WorkList.empty()) { const Constant *PC = WorkList.back().first; intptr_t PA = WorkList.back().second; WorkList.pop_back(); if (isa(PC)) { continue; } else if (const ConstantVector *CP = dyn_cast(PC)) { unsigned ElementSize = TD->getTypePaddedSize(CP->getType()->getElementType()); for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) WorkList.push_back(CPair(CP->getOperand(i), PA+i*ElementSize)); } else if (const ConstantExpr *CE = dyn_cast(PC)) { // // FIXME: Handle ConstantExpression. See EE::getConstantValue() // switch (CE->getOpcode()) { case Instruction::GetElementPtr: { SmallVector Indices(CE->op_begin()+1, CE->op_end()); ScatteredOffset = TD->getIndexedOffset(CE->getOperand(0)->getType(), &Indices[0], Indices.size()); WorkList.push_back(CPair(CE->getOperand(0), PA)); break; } case Instruction::Add: default: cerr << "ConstantExpr not handled as global var init: " << *CE << "\n"; abort(); break; } } else if (PC->getType()->isSingleValueType()) { unsigned char *ptr = (unsigned char *)PA; switch (PC->getType()->getTypeID()) { case Type::IntegerTyID: { unsigned NumBits = cast(PC->getType())->getBitWidth(); uint64_t val = cast(PC)->getZExtValue(); if (NumBits <= 8) ptr[0] = val; else if (NumBits <= 16) { if (TD->isBigEndian()) val = ByteSwap_16(val); ptr[0] = val; ptr[1] = val >> 8; } else if (NumBits <= 32) { if (TD->isBigEndian()) val = ByteSwap_32(val); ptr[0] = val; ptr[1] = val >> 8; ptr[2] = val >> 16; ptr[3] = val >> 24; } else if (NumBits <= 64) { if (TD->isBigEndian()) val = ByteSwap_64(val); ptr[0] = val; ptr[1] = val >> 8; ptr[2] = val >> 16; ptr[3] = val >> 24; ptr[4] = val >> 32; ptr[5] = val >> 40; ptr[6] = val >> 48; ptr[7] = val >> 56; } else { assert(0 && "Not implemented: bit widths > 64"); } break; } case Type::FloatTyID: { uint32_t val = cast(PC)->getValueAPF().bitcastToAPInt(). getZExtValue(); if (TD->isBigEndian()) val = ByteSwap_32(val); ptr[0] = val; ptr[1] = val >> 8; ptr[2] = val >> 16; ptr[3] = val >> 24; break; } case Type::DoubleTyID: { uint64_t val = cast(PC)->getValueAPF().bitcastToAPInt(). getZExtValue(); if (TD->isBigEndian()) val = ByteSwap_64(val); ptr[0] = val; ptr[1] = val >> 8; ptr[2] = val >> 16; ptr[3] = val >> 24; ptr[4] = val >> 32; ptr[5] = val >> 40; ptr[6] = val >> 48; ptr[7] = val >> 56; break; } case Type::PointerTyID: if (isa(PC)) memset(ptr, 0, TD->getPointerSize()); else if (const GlobalValue* GV = dyn_cast(PC)) { // FIXME: what about function stubs? MRs.push_back(MachineRelocation::getGV(PA-(intptr_t)Addr, MachineRelocation::VANILLA, const_cast(GV), ScatteredOffset)); ScatteredOffset = 0; } else assert(0 && "Unknown constant pointer type!"); break; default: cerr << "ERROR: Constant unimp for type: " << *PC->getType() << "\n"; abort(); } } else if (isa(PC)) { memset((void*)PA, 0, (size_t)TD->getTypePaddedSize(PC->getType())); } else if (const ConstantArray *CPA = dyn_cast(PC)) { unsigned ElementSize = TD->getTypePaddedSize(CPA->getType()->getElementType()); for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i) WorkList.push_back(CPair(CPA->getOperand(i), PA+i*ElementSize)); } else if (const ConstantStruct *CPS = dyn_cast(PC)) { const StructLayout *SL = TD->getStructLayout(cast(CPS->getType())); for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) WorkList.push_back(CPair(CPS->getOperand(i), PA+SL->getElementOffset(i))); } else { cerr << "Bad Type: " << *PC->getType() << "\n"; assert(0 && "Unknown constant type to initialize memory with!"); } } } MachOSym::MachOSym(const GlobalValue *gv, std::string name, uint8_t sect, TargetMachine &TM) : GV(gv), n_strx(0), n_type(sect == NO_SECT ? N_UNDF : N_SECT), n_sect(sect), n_desc(0), n_value(0) { const TargetAsmInfo *TAI = TM.getTargetAsmInfo(); switch (GV->getLinkage()) { default: assert(0 && "Unexpected linkage type!"); break; case GlobalValue::WeakLinkage: case GlobalValue::LinkOnceLinkage: case GlobalValue::CommonLinkage: assert(!isa(gv) && "Unexpected linkage type for Function!"); case GlobalValue::ExternalLinkage: GVName = TAI->getGlobalPrefix() + name; n_type |= GV->hasHiddenVisibility() ? N_PEXT : N_EXT; break; case GlobalValue::InternalLinkage: GVName = TAI->getGlobalPrefix() + name; break; } }