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https://github.com/c64scene-ar/llvm-6502.git
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d2030e6c99
entries in the correct order, fixing several fixmes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29902 91177308-0d34-0410-b5e6-96231b3b80d8
516 lines
18 KiB
C++
516 lines
18 KiB
C++
//===-- MachOWriter.cpp - Target-independent Mach-O Writer code -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by Nate Begeman and is distributed under the
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// University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the target-independent Mach-O writer. This file writes
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// out the Mach-O file in the following order:
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//
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// #1 FatHeader (universal-only)
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// #2 FatArch (universal-only, 1 per universal arch)
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// Per arch:
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// #3 Header
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// #4 Load Commands
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// #5 Sections
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// #6 Relocations
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// #7 Symbols
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// #8 Strings
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Module.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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#include "llvm/CodeGen/MachineConstantPool.h"
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#include "llvm/CodeGen/MachineRelocation.h"
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#include "llvm/CodeGen/MachOWriter.h"
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#include "llvm/Target/TargetJITInfo.h"
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#include "llvm/Support/Mangler.h"
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#include "llvm/Support/MathExtras.h"
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#include <algorithm>
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#include <iostream>
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// MachOCodeEmitter Implementation
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//===----------------------------------------------------------------------===//
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namespace llvm {
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/// MachOCodeEmitter - This class is used by the MachOWriter to emit the code
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/// for functions to the Mach-O file.
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class MachOCodeEmitter : public MachineCodeEmitter {
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MachOWriter &MOW;
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/// MOS - The current section we're writing to
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MachOWriter::MachOSection *MOS;
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/// Relocations - These are the relocations that the function needs, as
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/// emitted.
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std::vector<MachineRelocation> Relocations;
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/// MBBLocations - This vector is a mapping from MBB ID's to their address.
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/// It is filled in by the StartMachineBasicBlock callback and queried by
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/// the getMachineBasicBlockAddress callback.
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std::vector<intptr_t> MBBLocations;
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public:
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MachOCodeEmitter(MachOWriter &mow) : MOW(mow) {}
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void startFunction(MachineFunction &F);
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bool finishFunction(MachineFunction &F);
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void addRelocation(const MachineRelocation &MR) {
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Relocations.push_back(MR);
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}
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virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) {
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if (MBBLocations.size() <= (unsigned)MBB->getNumber())
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MBBLocations.resize((MBB->getNumber()+1)*2);
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MBBLocations[MBB->getNumber()] = getCurrentPCValue();
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}
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virtual intptr_t getConstantPoolEntryAddress(unsigned Index) const {
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assert(0 && "CP not implementated yet!");
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return 0;
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}
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virtual intptr_t getJumpTableEntryAddress(unsigned Index) const {
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assert(0 && "JT not implementated yet!");
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return 0;
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}
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virtual intptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const {
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assert(MBBLocations.size() > (unsigned)MBB->getNumber() &&
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MBBLocations[MBB->getNumber()] && "MBB not emitted!");
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return MBBLocations[MBB->getNumber()];
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}
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/// JIT SPECIFIC FUNCTIONS - DO NOT IMPLEMENT THESE HERE!
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void startFunctionStub(unsigned StubSize) {
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assert(0 && "JIT specific function called!");
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abort();
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}
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void *finishFunctionStub(const Function *F) {
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assert(0 && "JIT specific function called!");
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abort();
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return 0;
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}
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};
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}
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/// startFunction - This callback is invoked when a new machine function is
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/// about to be emitted.
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void MachOCodeEmitter::startFunction(MachineFunction &F) {
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// Align the output buffer to the appropriate alignment, power of 2.
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// FIXME: GENERICIZE!!
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unsigned Align = 4;
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// Get the Mach-O Section that this function belongs in.
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MOS = &MOW.getTextSection();
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// FIXME: better memory management
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MOS->SectionData.reserve(4096);
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BufferBegin = &(MOS->SectionData[0]);
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BufferEnd = BufferBegin + MOS->SectionData.capacity();
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CurBufferPtr = BufferBegin + MOS->size;
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// Upgrade the section alignment if required.
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if (MOS->align < Align) MOS->align = Align;
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// Make sure we only relocate to this function's MBBs.
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MBBLocations.clear();
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}
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/// finishFunction - This callback is invoked after the function is completely
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/// finished.
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bool MachOCodeEmitter::finishFunction(MachineFunction &F) {
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MOS->size += CurBufferPtr - BufferBegin;
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// Get a symbol for the function to add to the symbol table
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const GlobalValue *FuncV = F.getFunction();
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MachOWriter::MachOSym FnSym(FuncV, MOW.Mang->getValueName(FuncV), MOS->Index);
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// Figure out the binding (linkage) of the symbol.
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switch (FuncV->getLinkage()) {
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default:
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// appending linkage is illegal for functions.
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assert(0 && "Unknown linkage type!");
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case GlobalValue::ExternalLinkage:
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FnSym.n_type |= MachOWriter::MachOSym::N_EXT;
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break;
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case GlobalValue::InternalLinkage:
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break;
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}
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// Resolve the function's relocations either to concrete pointers in the case
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// of branches from one block to another, or to target relocation entries.
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for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
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MachineRelocation &MR = Relocations[i];
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if (MR.isBasicBlock()) {
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void *MBBAddr = (void *)getMachineBasicBlockAddress(MR.getBasicBlock());
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MR.setResultPointer(MBBAddr);
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MOW.TM.getJITInfo()->relocate(BufferBegin, &MR, 1, 0);
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// FIXME: we basically want the JITInfo relocate() function to rewrite
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// this guy right now, so we just write the correct displacement
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// to the file.
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} else {
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// isString | isGV | isCPI | isJTI
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// FIXME: do something smart here. We won't be able to relocate these
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// until the sections are all layed out, but we still need to
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// record them. Maybe emit TargetRelocations and then resolve
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// those at file writing time?
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}
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}
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Relocations.clear();
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// Finally, add it to the symtab.
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MOW.SymbolTable.push_back(FnSym);
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return false;
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}
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//===----------------------------------------------------------------------===//
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// MachOWriter Implementation
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//===----------------------------------------------------------------------===//
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MachOWriter::MachOWriter(std::ostream &o, TargetMachine &tm) : O(o), TM(tm) {
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// FIXME: set cpu type and cpu subtype somehow from TM
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is64Bit = TM.getTargetData()->getPointerSizeInBits() == 64;
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isLittleEndian = TM.getTargetData()->isLittleEndian();
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// Create the machine code emitter object for this target.
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MCE = new MachOCodeEmitter(*this);
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}
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MachOWriter::~MachOWriter() {
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delete MCE;
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}
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void MachOWriter::AddSymbolToSection(MachOSection &Sec, GlobalVariable *GV) {
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const Type *Ty = GV->getType()->getElementType();
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unsigned Size = TM.getTargetData()->getTypeSize(Ty);
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unsigned Align = Log2_32(TM.getTargetData()->getTypeAlignment(Ty));
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MachOSym Sym(GV, Mang->getValueName(GV), Sec.Index);
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// Reserve space in the .bss section for this symbol while maintaining the
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// desired section alignment, which must be at least as much as required by
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// this symbol.
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if (Align) {
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Sec.align = std::max(Sec.align, Align);
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Sec.size = (Sec.size + Align - 1) & ~(Align-1);
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}
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// Record the offset of the symbol, and then allocate space for it.
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Sym.n_value = Sec.size;
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Sec.size += Size;
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switch (GV->getLinkage()) {
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default: // weak/linkonce handled above
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assert(0 && "Unexpected linkage type!");
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case GlobalValue::ExternalLinkage:
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Sym.n_type |= MachOSym::N_EXT;
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break;
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case GlobalValue::InternalLinkage:
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break;
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}
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SymbolTable.push_back(Sym);
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}
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void MachOWriter::EmitGlobal(GlobalVariable *GV) {
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const Type *Ty = GV->getType()->getElementType();
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unsigned Size = TM.getTargetData()->getTypeSize(Ty);
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bool NoInit = !GV->hasInitializer();
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// If this global has a zero initializer, it is part of the .bss or common
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// section.
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if (NoInit || GV->getInitializer()->isNullValue()) {
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// If this global is part of the common block, add it now. Variables are
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// part of the common block if they are zero initialized and allowed to be
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// merged with other symbols.
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if (NoInit || GV->hasLinkOnceLinkage() || GV->hasWeakLinkage()) {
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MachOWriter::MachOSym ExtOrCommonSym(GV, Mang->getValueName(GV),
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MachOSym::NO_SECT);
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ExtOrCommonSym.n_type |= MachOSym::N_EXT;
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// For undefined (N_UNDF) external (N_EXT) types, n_value is the size in
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// bytes of the symbol.
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ExtOrCommonSym.n_value = Size;
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// If the symbol is external, we'll put it on a list of symbols whose
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// addition to the symbol table is being pended until we find a reference
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if (NoInit)
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PendingSyms.push_back(ExtOrCommonSym);
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else
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SymbolTable.push_back(ExtOrCommonSym);
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return;
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}
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// Otherwise, this symbol is part of the .bss section.
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MachOSection &BSS = getBSSSection();
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AddSymbolToSection(BSS, GV);
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return;
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}
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// Scalar read-only data goes in a literal section if the scalar is 4, 8, or
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// 16 bytes, or a cstring. Other read only data goes into a regular const
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// section. Read-write data goes in the data section.
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MachOSection &Sec = GV->isConstant() ? getConstSection(Ty) : getDataSection();
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AddSymbolToSection(Sec, GV);
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// FIXME: actually write out the initializer to the section. This will
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// require ExecutionEngine's InitializeMemory() function, which will need to
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// be enhanced to support relocations.
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}
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bool MachOWriter::runOnMachineFunction(MachineFunction &MF) {
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// Nothing to do here, this is all done through the MCE object.
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return false;
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}
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bool MachOWriter::doInitialization(Module &M) {
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// Set the magic value, now that we know the pointer size and endianness
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Header.setMagic(isLittleEndian, is64Bit);
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// Set the file type
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// FIXME: this only works for object files, we do not support the creation
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// of dynamic libraries or executables at this time.
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Header.filetype = MachOHeader::MH_OBJECT;
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Mang = new Mangler(M);
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return false;
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}
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/// doFinalization - Now that the module has been completely processed, emit
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/// the Mach-O file to 'O'.
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bool MachOWriter::doFinalization(Module &M) {
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// FIXME: we don't handle debug info yet, we should probably do that.
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// Okay, the.text section has been completed, build the .data, .bss, and
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// "common" sections next.
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for (Module::global_iterator I = M.global_begin(), E = M.global_end();
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I != E; ++I)
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EmitGlobal(I);
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// Emit the symbol table to temporary buffers, so that we know the size of
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// the string table when we write the load commands in the next phase.
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BufferSymbolAndStringTable();
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// Emit the header and load commands.
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EmitHeaderAndLoadCommands();
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// Emit the text and data sections.
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EmitSections();
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// Emit the relocation entry data for each section.
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// FIXME: presumably this should be a virtual method, since different targets
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// have different relocation types.
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EmitRelocations();
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// Write the symbol table and the string table to the end of the file.
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O.write((char*)&SymT[0], SymT.size());
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O.write((char*)&StrT[0], StrT.size());
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// We are done with the abstract symbols.
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SectionList.clear();
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SymbolTable.clear();
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DynamicSymbolTable.clear();
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// Release the name mangler object.
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delete Mang; Mang = 0;
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return false;
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}
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void MachOWriter::EmitHeaderAndLoadCommands() {
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// Step #0: Fill in the segment load command size, since we need it to figure
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// out the rest of the header fields
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MachOSegment SEG("", is64Bit);
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SEG.nsects = SectionList.size();
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SEG.cmdsize = SEG.cmdSize(is64Bit) +
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SEG.nsects * SectionList.begin()->cmdSize(is64Bit);
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// Step #1: calculate the number of load commands. We always have at least
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// one, for the LC_SEGMENT load command, plus two for the normal
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// and dynamic symbol tables, if there are any symbols.
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Header.ncmds = SymbolTable.empty() ? 1 : 3;
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// Step #2: calculate the size of the load commands
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Header.sizeofcmds = SEG.cmdsize;
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if (!SymbolTable.empty())
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Header.sizeofcmds += SymTab.cmdsize + DySymTab.cmdsize;
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// Step #3: write the header to the file
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// Local alias to shortenify coming code.
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DataBuffer &FH = Header.HeaderData;
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outword(FH, Header.magic);
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outword(FH, Header.cputype);
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outword(FH, Header.cpusubtype);
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outword(FH, Header.filetype);
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outword(FH, Header.ncmds);
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outword(FH, Header.sizeofcmds);
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outword(FH, Header.flags);
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if (is64Bit)
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outword(FH, Header.reserved);
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// Step #4: Finish filling in the segment load command and write it out
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for (std::list<MachOSection>::iterator I = SectionList.begin(),
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E = SectionList.end(); I != E; ++I)
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SEG.filesize += I->size;
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SEG.vmsize = SEG.filesize;
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SEG.fileoff = Header.cmdSize(is64Bit) + Header.sizeofcmds;
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outword(FH, SEG.cmd);
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outword(FH, SEG.cmdsize);
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outstring(FH, SEG.segname, 16);
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outaddr(FH, SEG.vmaddr);
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outaddr(FH, SEG.vmsize);
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outaddr(FH, SEG.fileoff);
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outaddr(FH, SEG.filesize);
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outword(FH, SEG.maxprot);
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outword(FH, SEG.initprot);
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outword(FH, SEG.nsects);
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outword(FH, SEG.flags);
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// Step #5: Write out the section commands for each section
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for (std::list<MachOSection>::iterator I = SectionList.begin(),
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E = SectionList.end(); I != E; ++I) {
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I->offset = SEG.fileoff; // FIXME: separate offset
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outstring(FH, I->sectname, 16);
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outstring(FH, I->segname, 16);
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outaddr(FH, I->addr);
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outaddr(FH, I->size);
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outword(FH, I->offset);
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outword(FH, I->align);
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outword(FH, I->reloff);
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outword(FH, I->nreloc);
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outword(FH, I->flags);
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outword(FH, I->reserved1);
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outword(FH, I->reserved2);
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if (is64Bit)
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outword(FH, I->reserved3);
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}
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// Step #6: Emit LC_SYMTAB/LC_DYSYMTAB load commands
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// FIXME: add size of relocs
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SymTab.symoff = SEG.fileoff + SEG.filesize;
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SymTab.nsyms = SymbolTable.size();
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SymTab.stroff = SymTab.symoff + SymT.size();
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SymTab.strsize = StrT.size();
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outword(FH, SymTab.cmd);
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outword(FH, SymTab.cmdsize);
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outword(FH, SymTab.symoff);
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outword(FH, SymTab.nsyms);
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outword(FH, SymTab.stroff);
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outword(FH, SymTab.strsize);
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// FIXME: set DySymTab fields appropriately
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// We should probably just update these in BufferSymbolAndStringTable since
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// thats where we're partitioning up the different kinds of symbols.
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outword(FH, DySymTab.cmd);
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outword(FH, DySymTab.cmdsize);
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outword(FH, DySymTab.ilocalsym);
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outword(FH, DySymTab.nlocalsym);
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outword(FH, DySymTab.iextdefsym);
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outword(FH, DySymTab.nextdefsym);
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outword(FH, DySymTab.iundefsym);
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outword(FH, DySymTab.nundefsym);
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outword(FH, DySymTab.tocoff);
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outword(FH, DySymTab.ntoc);
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outword(FH, DySymTab.modtaboff);
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outword(FH, DySymTab.nmodtab);
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outword(FH, DySymTab.extrefsymoff);
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outword(FH, DySymTab.nextrefsyms);
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outword(FH, DySymTab.indirectsymoff);
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outword(FH, DySymTab.nindirectsyms);
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outword(FH, DySymTab.extreloff);
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outword(FH, DySymTab.nextrel);
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outword(FH, DySymTab.locreloff);
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outword(FH, DySymTab.nlocrel);
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O.write((char*)&FH[0], FH.size());
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}
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/// EmitSections - Now that we have constructed the file header and load
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/// commands, emit the data for each section to the file.
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void MachOWriter::EmitSections() {
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for (std::list<MachOSection>::iterator I = SectionList.begin(),
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E = SectionList.end(); I != E; ++I) {
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O.write((char*)&I->SectionData[0], I->size);
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}
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}
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void MachOWriter::EmitRelocations() {
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// FIXME: this should probably be a pure virtual function, since the
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// relocation types and layout of the relocations themselves are target
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// specific.
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}
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/// PartitionByLocal - Simple boolean predicate that returns true if Sym is
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/// a local symbol rather than an external symbol.
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bool MachOWriter::PartitionByLocal(const MachOSym &Sym) {
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// FIXME: Not totally sure if private extern counts as external
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return (Sym.n_type & (MachOSym::N_EXT | MachOSym::N_PEXT)) == 0;
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}
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/// PartitionByDefined - Simple boolean predicate that returns true if Sym is
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/// defined in this module.
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bool MachOWriter::PartitionByDefined(const MachOSym &Sym) {
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// FIXME: Do N_ABS or N_INDR count as defined?
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return (Sym.n_type & MachOSym::N_SECT) == MachOSym::N_SECT;
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}
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/// BufferSymbolAndStringTable - Sort the symbols we encountered and assign them
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/// each a string table index so that they appear in the correct order in the
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/// output file.
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void MachOWriter::BufferSymbolAndStringTable() {
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// The order of the symbol table is:
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// 1. local symbols
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// 2. defined external symbols (sorted by name)
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// 3. undefined external symbols (sorted by name)
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// Sort the symbols by name, so that when we partition the symbols by scope
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// 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<MachOSym>::iterator I = SymbolTable.begin(),
|
|
E = SymbolTable.end(); I != E; ++I) {
|
|
if (!PartitionByLocal(*I)) {
|
|
std::partition(I, E, PartitionByDefined);
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Write out a leading zero byte when emitting string table, for n_strx == 0
|
|
// which means an empty string.
|
|
outbyte(StrT, 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<MachOSym>::reverse_iterator I = SymbolTable.rbegin(),
|
|
E = SymbolTable.rend(); I != E; ++I) {
|
|
if (I->GVName == "") {
|
|
I->n_strx = 0;
|
|
} else {
|
|
I->n_strx = StrT.size();
|
|
outstring(StrT, I->GVName, I->GVName.length()+1);
|
|
}
|
|
}
|
|
|
|
for (std::vector<MachOSym>::iterator I = SymbolTable.begin(),
|
|
E = SymbolTable.end(); I != E; ++I) {
|
|
// Emit nlist to buffer
|
|
outword(SymT, I->n_strx);
|
|
outbyte(SymT, I->n_type);
|
|
outbyte(SymT, I->n_sect);
|
|
outhalf(SymT, I->n_desc);
|
|
outaddr(SymT, I->n_value);
|
|
}
|
|
}
|