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llvm-6502/lib/CodeGen/MachOWriter.cpp
Duncan Sands 667d4b8de6 Introduce new linkage types linkonce_odr, weak_odr, common_odr 
and extern_weak_odr.  These are the same as the non-odr versions,
except that they indicate that the global will only be overridden
by an *equivalent* global.  In C, a function with weak linkage can
be overridden by a function which behaves completely differently.
This means that IP passes have to skip weak functions, since any
deductions made from the function definition might be wrong, since
the definition could be replaced by something completely different
at link time.   This is not allowed in C++, thanks to the ODR
(One-Definition-Rule): if a function is replaced by another at
link-time, then the new function must be the same as the original
function.  If a language knows that a function or other global can
only be overridden by an equivalent global, it can give it the
weak_odr linkage type, and the optimizers will understand that it
is alright to make deductions based on the function body.  The
code generators on the other hand map weak and weak_odr linkage
to the same thing.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66339 91177308-0d34-0410-b5e6-96231b3b80d8
2009-03-07 15:45:40 +00:00

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//===-- 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 <algorithm>
#include <cstring>
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<MachineRelocation> 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<uintptr_t> CPLocations;
/// CPSections - This is a map of constant pool indices to the MachOSection
/// containing the constant pool entry for that index.
std::vector<unsigned> 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<uintptr_t> 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<uintptr_t> 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 startGVStub(const GlobalValue* F, void *Buffer,
unsigned StubSize) {
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<MachineConstantPoolEntry> &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<MachineJumpTableEntry> &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<MachineBasicBlock*> &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->hasLocalLinkage()) {
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<MachOSection*>::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<MachOSection*>::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<MachOSection*>::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<MachOSection*>::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<MachOSection*>::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<GlobalValue*>::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<MachOSym>::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<MachOSym>::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<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();
StrTOut.outstring(I->GVName, I->GVName.length()+1);
}
}
OutputBuffer SymTOut(SymT, is64Bit, isLittleEndian);
unsigned index = 0;
for (std::vector<MachOSym>::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<GlobalValue*>(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<MachineRelocation> &MRs) {
typedef std::pair<const Constant*, intptr_t> CPair;
std::vector<CPair> 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<UndefValue>(PC)) {
continue;
} else if (const ConstantVector *CP = dyn_cast<ConstantVector>(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<ConstantExpr>(PC)) {
//
// FIXME: Handle ConstantExpression. See EE::getConstantValue()
//
switch (CE->getOpcode()) {
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> 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<IntegerType>(PC->getType())->getBitWidth();
uint64_t val = cast<ConstantInt>(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<ConstantFP>(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<ConstantFP>(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<ConstantPointerNull>(PC))
memset(ptr, 0, TD->getPointerSize());
else if (const GlobalValue* GV = dyn_cast<GlobalValue>(PC)) {
// FIXME: what about function stubs?
MRs.push_back(MachineRelocation::getGV(PA-(intptr_t)Addr,
MachineRelocation::VANILLA,
const_cast<GlobalValue*>(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<ConstantAggregateZero>(PC)) {
memset((void*)PA, 0, (size_t)TD->getTypePaddedSize(PC->getType()));
} else if (const ConstantArray *CPA = dyn_cast<ConstantArray>(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<ConstantStruct>(PC)) {
const StructLayout *SL =
TD->getStructLayout(cast<StructType>(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::WeakAnyLinkage:
case GlobalValue::WeakODRLinkage:
case GlobalValue::LinkOnceAnyLinkage:
case GlobalValue::LinkOnceODRLinkage:
case GlobalValue::CommonAnyLinkage:
case GlobalValue::CommonODRLinkage:
assert(!isa<Function>(gv) && "Unexpected linkage type for Function!");
case GlobalValue::ExternalLinkage:
GVName = TAI->getGlobalPrefix() + name;
n_type |= GV->hasHiddenVisibility() ? N_PEXT : N_EXT;
break;
case GlobalValue::PrivateLinkage:
GVName = TAI->getPrivateGlobalPrefix() + name;
break;
case GlobalValue::InternalLinkage:
GVName = TAI->getGlobalPrefix() + name;
break;
}
}
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