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//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachOWriterInfo.h"
using namespace llvm;
namespace {
class MachObjectWriter {
// See <mach-o/loader.h>.
enum {
Header_Magic32 = 0xFEEDFACE,
Header_Magic64 = 0xFEEDFACF
};
static const unsigned Header32Size = 28;
static const unsigned Header64Size = 32;
static const unsigned SegmentLoadCommand32Size = 56;
static const unsigned Section32Size = 68;
enum HeaderFileType {
HFT_Object = 0x1
};
enum LoadCommandType {
LCT_Segment = 0x1
};
raw_ostream &OS;
bool IsLSB;
public:
MachObjectWriter(raw_ostream &_OS, bool _IsLSB = true)
: OS(_OS), IsLSB(_IsLSB) {
}
/// @name Helper Methods
/// @{
void Write32(uint32_t Value) {
if (IsLSB) {
OS << char(Value >> 0);
OS << char(Value >> 8);
OS << char(Value >> 16);
OS << char(Value >> 24);
} else {
OS << char(Value >> 24);
OS << char(Value >> 16);
OS << char(Value >> 8);
OS << char(Value >> 0);
}
}
void WriteZeros(unsigned N) {
const char Zeros[16] = { 0 };
for (unsigned i = 0, e = N / 16; i != e; ++i)
OS << StringRef(Zeros, 16);
OS << StringRef(Zeros, N % 16);
}
void WriteString(const StringRef &Str, unsigned ZeroFillSize = 0) {
OS << Str;
if (ZeroFillSize)
WriteZeros(ZeroFillSize - Str.size());
}
/// @}
static unsigned getPrologSize32(unsigned NumSections) {
return Header32Size + SegmentLoadCommand32Size +
NumSections * Section32Size;
}
void WriteHeader32(unsigned NumSections) {
// struct mach_header (28 bytes)
uint64_t Start = OS.tell();
(void) Start;
Write32(Header_Magic32);
// FIXME: Support cputype.
Write32(TargetMachOWriterInfo::HDR_CPU_TYPE_I386);
// FIXME: Support cpusubtype.
Write32(TargetMachOWriterInfo::HDR_CPU_SUBTYPE_I386_ALL);
Write32(HFT_Object);
// Object files have a single load command, the segment.
Write32(1);
Write32(SegmentLoadCommand32Size + NumSections * Section32Size);
Write32(0); // Flags
assert(OS.tell() - Start == Header32Size);
}
void WriteLoadCommandHeader(uint32_t Cmd, uint32_t CmdSize) {
assert((CmdSize & 0x3) == 0 && "Invalid size!");
Write32(Cmd);
Write32(CmdSize);
}
void WriteSegmentLoadCommand32(unsigned NumSections) {
// struct segment_command (56 bytes)
uint64_t Start = OS.tell();
(void) Start;
Write32(LCT_Segment);
Write32(SegmentLoadCommand32Size + NumSections * Section32Size);
WriteString("", 16);
Write32(0); // vmaddr
Write32(0); // vmsize
Write32(Header32Size + SegmentLoadCommand32Size +
NumSections * Section32Size); // file offset
Write32(0); // file size
Write32(0x7); // maxprot
Write32(0x7); // initprot
Write32(NumSections);
Write32(0); // flags
assert(OS.tell() - Start == SegmentLoadCommand32Size);
}
void WriteSection32(const MCSectionData &SD) {
// struct section (68 bytes)
uint64_t Start = OS.tell();
(void) Start;
// FIXME: cast<> support!
const MCSectionMachO &Section =
static_cast<const MCSectionMachO&>(SD.getSection());
WriteString(Section.getSectionName(), 16);
WriteString(Section.getSegmentName(), 16);
Write32(0); // address
Write32(SD.getFileSize()); // size
Write32(SD.getFileOffset());
assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
Write32(Log2_32(SD.getAlignment()));
Write32(0); // file offset of relocation entries
Write32(0); // number of relocation entrions
Write32(Section.getTypeAndAttributes());
Write32(0); // reserved1
Write32(Section.getStubSize()); // reserved2
assert(OS.tell() - Start == Section32Size);
}
};
}
/* *** */
MCFragment::MCFragment(MCSectionData *SD)
{
if (SD)
SD->getFragmentList().push_back(this);
}
/* *** */
MCSectionData::MCSectionData() : Section(*(MCSection*)0) {}
MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
: Section(_Section),
Alignment(1),
FileOffset(0),
FileSize(0)
{
if (A)
A->getSectionList().push_back(this);
}
void MCSectionData::WriteFileData(raw_ostream &OS) const {
}
/* *** */
MCAssembler::MCAssembler(raw_ostream &_OS) : OS(_OS) {}
MCAssembler::~MCAssembler() {
}
void MCAssembler::Finish() {
unsigned NumSections = Sections.size();
// Compute the file offsets so we can write in a single pass.
uint64_t Offset = MachObjectWriter::getPrologSize32(NumSections);
for (iterator it = begin(), ie = end(); it != ie; ++it) {
it->setFileOffset(Offset);
Offset += it->getFileSize();
}
MachObjectWriter MOW(OS);
// Write the prolog, starting with the header and load command...
MOW.WriteHeader32(NumSections);
MOW.WriteSegmentLoadCommand32(NumSections);
// ... and then the section headers.
for (iterator it = begin(), ie = end(); it != ie; ++it)
MOW.WriteSection32(*it);
// Finally, write the section data.
for (iterator it = begin(), ie = end(); it != ie; ++it)
it->WriteFileData(OS);
OS.flush();
}
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