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section offset). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79734 91177308-0d34-0410-b5e6-96231b3b80d8
402 lines
10 KiB
C++
402 lines
10 KiB
C++
//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/MC/MCSectionMachO.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetMachOWriterInfo.h"
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using namespace llvm;
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namespace {
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class MachObjectWriter {
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// See <mach-o/loader.h>.
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enum {
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Header_Magic32 = 0xFEEDFACE,
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Header_Magic64 = 0xFEEDFACF
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};
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static const unsigned Header32Size = 28;
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static const unsigned Header64Size = 32;
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static const unsigned SegmentLoadCommand32Size = 56;
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static const unsigned Section32Size = 68;
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enum HeaderFileType {
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HFT_Object = 0x1
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};
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enum LoadCommandType {
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LCT_Segment = 0x1
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};
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raw_ostream &OS;
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bool IsLSB;
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public:
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MachObjectWriter(raw_ostream &_OS, bool _IsLSB = true)
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: OS(_OS), IsLSB(_IsLSB) {
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}
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/// @name Helper Methods
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/// @{
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void Write8(uint8_t Value) {
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OS << char(Value);
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}
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void Write16(uint16_t Value) {
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if (IsLSB) {
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Write8(uint8_t(Value >> 0));
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Write8(uint8_t(Value >> 8));
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} else {
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Write8(uint8_t(Value >> 8));
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Write8(uint8_t(Value >> 0));
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}
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}
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void Write32(uint32_t Value) {
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if (IsLSB) {
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Write16(uint16_t(Value >> 0));
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Write16(uint16_t(Value >> 16));
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} else {
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Write16(uint16_t(Value >> 16));
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Write16(uint16_t(Value >> 0));
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}
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}
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void Write64(uint64_t Value) {
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if (IsLSB) {
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Write32(uint32_t(Value >> 0));
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Write32(uint32_t(Value >> 32));
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} else {
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Write32(uint32_t(Value >> 32));
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Write32(uint32_t(Value >> 0));
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}
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}
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void WriteZeros(unsigned N) {
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const char Zeros[16] = { 0 };
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for (unsigned i = 0, e = N / 16; i != e; ++i)
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OS << StringRef(Zeros, 16);
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OS << StringRef(Zeros, N % 16);
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}
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void WriteString(const StringRef &Str, unsigned ZeroFillSize = 0) {
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OS << Str;
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if (ZeroFillSize)
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WriteZeros(ZeroFillSize - Str.size());
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}
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/// @}
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static unsigned getPrologSize32(unsigned NumSections) {
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return Header32Size + SegmentLoadCommand32Size +
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NumSections * Section32Size;
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}
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void WriteHeader32(unsigned NumSections) {
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// struct mach_header (28 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(Header_Magic32);
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// FIXME: Support cputype.
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Write32(TargetMachOWriterInfo::HDR_CPU_TYPE_I386);
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// FIXME: Support cpusubtype.
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Write32(TargetMachOWriterInfo::HDR_CPU_SUBTYPE_I386_ALL);
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Write32(HFT_Object);
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// Object files have a single load command, the segment.
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Write32(1);
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Write32(SegmentLoadCommand32Size + NumSections * Section32Size);
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Write32(0); // Flags
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assert(OS.tell() - Start == Header32Size);
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}
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void WriteLoadCommandHeader(uint32_t Cmd, uint32_t CmdSize) {
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assert((CmdSize & 0x3) == 0 && "Invalid size!");
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Write32(Cmd);
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Write32(CmdSize);
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}
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/// WriteSegmentLoadCommand32 - Write a 32-bit segment load command.
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///
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/// \arg NumSections - The number of sections in this segment.
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/// \arg SectionDataSize - The total size of the sections.
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void WriteSegmentLoadCommand32(unsigned NumSections,
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uint64_t SectionDataSize) {
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// struct segment_command (56 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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Write32(LCT_Segment);
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Write32(SegmentLoadCommand32Size + NumSections * Section32Size);
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WriteString("", 16);
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Write32(0); // vmaddr
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Write32(SectionDataSize); // vmsize
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Write32(Header32Size + SegmentLoadCommand32Size +
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NumSections * Section32Size); // file offset
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Write32(SectionDataSize); // file size
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Write32(0x7); // maxprot
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Write32(0x7); // initprot
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Write32(NumSections);
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Write32(0); // flags
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assert(OS.tell() - Start == SegmentLoadCommand32Size);
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}
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void WriteSection32(const MCSectionData &SD) {
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// struct section (68 bytes)
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uint64_t Start = OS.tell();
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(void) Start;
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// FIXME: cast<> support!
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const MCSectionMachO &Section =
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static_cast<const MCSectionMachO&>(SD.getSection());
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WriteString(Section.getSectionName(), 16);
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WriteString(Section.getSegmentName(), 16);
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Write32(0); // address
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Write32(SD.getFileSize()); // size
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Write32(SD.getFileOffset());
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assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
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Write32(Log2_32(SD.getAlignment()));
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Write32(0); // file offset of relocation entries
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Write32(0); // number of relocation entrions
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Write32(Section.getTypeAndAttributes());
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Write32(0); // reserved1
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Write32(Section.getStubSize()); // reserved2
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assert(OS.tell() - Start == Section32Size);
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}
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};
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}
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/* *** */
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MCFragment::MCFragment() : Kind(FragmentType(~0)) {
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}
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MCFragment::MCFragment(FragmentType _Kind, MCSectionData *SD)
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: Kind(_Kind),
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FileSize(~UINT64_C(0))
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{
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if (SD)
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SD->getFragmentList().push_back(this);
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}
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MCFragment::~MCFragment() {
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}
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/* *** */
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MCSectionData::MCSectionData() : Section(*(MCSection*)0) {}
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MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
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: Section(_Section),
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Alignment(1),
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FileOffset(~UINT64_C(0)),
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FileSize(~UINT64_C(0))
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{
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if (A)
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A->getSectionList().push_back(this);
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}
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/* *** */
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MCAssembler::MCAssembler(raw_ostream &_OS) : OS(_OS) {}
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MCAssembler::~MCAssembler() {
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}
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void MCAssembler::LayoutSection(MCSectionData &SD) {
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uint64_t Offset = 0;
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for (MCSectionData::iterator it = SD.begin(), ie = SD.end(); it != ie; ++it) {
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MCFragment &F = *it;
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F.setOffset(Offset);
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// Evaluate fragment size.
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switch (F.getKind()) {
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case MCFragment::FT_Align: {
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MCAlignFragment &AF = cast<MCAlignFragment>(F);
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uint64_t AlignedOffset = RoundUpToAlignment(Offset, AF.getAlignment());
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uint64_t PaddingBytes = AlignedOffset - Offset;
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if (PaddingBytes > AF.getMaxBytesToEmit())
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AF.setFileSize(0);
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else
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AF.setFileSize(PaddingBytes);
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break;
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}
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case MCFragment::FT_Data:
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case MCFragment::FT_Fill:
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F.setFileSize(F.getMaxFileSize());
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break;
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case MCFragment::FT_Org: {
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MCOrgFragment &OF = cast<MCOrgFragment>(F);
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if (!OF.getOffset().isAbsolute())
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llvm_unreachable("FIXME: Not yet implemented!");
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uint64_t OrgOffset = OF.getOffset().getConstant();
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// FIXME: We need a way to communicate this error.
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if (OrgOffset < Offset)
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llvm_report_error("invalid .org offset '" + Twine(OrgOffset) +
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"' (section offset '" + Twine(Offset) + "'");
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F.setFileSize(OrgOffset - Offset);
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break;
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}
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}
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Offset += F.getFileSize();
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}
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// FIXME: Pad section?
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SD.setFileSize(Offset);
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}
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/// WriteFileData - Write the \arg F data to the output file.
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static void WriteFileData(raw_ostream &OS, const MCFragment &F,
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MachObjectWriter &MOW) {
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uint64_t Start = OS.tell();
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(void) Start;
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// FIXME: Embed in fragments instead?
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switch (F.getKind()) {
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case MCFragment::FT_Align: {
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MCAlignFragment &AF = cast<MCAlignFragment>(F);
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uint64_t Count = AF.getFileSize() / AF.getValueSize();
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// FIXME: This error shouldn't actually occur (the front end should emit
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// multiple .align directives to enforce the semantics it wants), but is
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// severe enough that we want to report it. How to handle this?
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if (Count * AF.getValueSize() != AF.getFileSize())
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llvm_report_error("undefined .align directive, value size '" +
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Twine(AF.getValueSize()) +
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"' is not a divisor of padding size '" +
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Twine(AF.getFileSize()) + "'");
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for (uint64_t i = 0; i != Count; ++i) {
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switch (AF.getValueSize()) {
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default:
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assert(0 && "Invalid size!");
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case 1: MOW.Write8 (uint8_t (AF.getValue())); break;
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case 2: MOW.Write16(uint16_t(AF.getValue())); break;
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case 4: MOW.Write32(uint32_t(AF.getValue())); break;
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case 8: MOW.Write64(uint64_t(AF.getValue())); break;
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}
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}
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break;
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}
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case MCFragment::FT_Data:
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OS << cast<MCDataFragment>(F).getContents().str();
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break;
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case MCFragment::FT_Fill: {
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MCFillFragment &FF = cast<MCFillFragment>(F);
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if (!FF.getValue().isAbsolute())
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llvm_unreachable("FIXME: Not yet implemented!");
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int64_t Value = FF.getValue().getConstant();
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for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
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switch (FF.getValueSize()) {
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default:
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assert(0 && "Invalid size!");
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case 1: MOW.Write8 (uint8_t (Value)); break;
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case 2: MOW.Write16(uint16_t(Value)); break;
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case 4: MOW.Write32(uint32_t(Value)); break;
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case 8: MOW.Write64(uint64_t(Value)); break;
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}
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}
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break;
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}
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case MCFragment::FT_Org: {
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MCOrgFragment &OF = cast<MCOrgFragment>(F);
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for (uint64_t i = 0, e = OF.getFileSize(); i != e; ++i)
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MOW.Write8(uint8_t(OF.getValue()));
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break;
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}
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}
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assert(OS.tell() - Start == F.getFileSize());
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}
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/// WriteFileData - Write the \arg SD data to the output file.
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static void WriteFileData(raw_ostream &OS, const MCSectionData &SD,
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MachObjectWriter &MOW) {
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uint64_t Start = OS.tell();
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(void) Start;
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for (MCSectionData::const_iterator it = SD.begin(),
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ie = SD.end(); it != ie; ++it)
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WriteFileData(OS, *it, MOW);
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assert(OS.tell() - Start == SD.getFileSize());
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}
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void MCAssembler::Finish() {
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unsigned NumSections = Sections.size();
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// Layout the sections and fragments.
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uint64_t Offset = MachObjectWriter::getPrologSize32(NumSections);
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uint64_t SectionDataSize = 0;
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for (iterator it = begin(), ie = end(); it != ie; ++it) {
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it->setFileOffset(Offset);
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LayoutSection(*it);
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Offset += it->getFileSize();
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SectionDataSize += it->getFileSize();
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}
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MachObjectWriter MOW(OS);
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// Write the prolog, starting with the header and load command...
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MOW.WriteHeader32(NumSections);
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MOW.WriteSegmentLoadCommand32(NumSections, SectionDataSize);
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// ... and then the section headers.
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for (iterator it = begin(), ie = end(); it != ie; ++it)
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MOW.WriteSection32(*it);
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// Finally, write the section data.
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for (iterator it = begin(), ie = end(); it != ie; ++it)
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WriteFileData(OS, *it, MOW);
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OS.flush();
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}
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