llvm-6502/lib/MC/MCMachOStreamer.cpp
2010-09-22 22:27:05 +00:00

687 lines
26 KiB
C++

//===- lib/MC/MCMachOStreamer.cpp - Mach-O Object Output ------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCMachOSymbolFlags.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetAsmBackend.h"
using namespace llvm;
namespace {
class MCMachOStreamer : public MCObjectStreamer {
private:
void EmitInstToFragment(const MCInst &Inst);
void EmitInstToData(const MCInst &Inst);
// FIXME: These will likely moved to a better place.
void MakeLineEntryForSection(const MCSection *Section);
const MCExpr * MakeStartMinusEndExpr(MCSymbol *Start, MCSymbol *End,
int IntVal);
void EmitDwarfFileTable(void);
public:
MCMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
raw_ostream &OS, MCCodeEmitter *Emitter)
: MCObjectStreamer(Context, TAB, OS, Emitter, true) {}
/// @name MCStreamer Interface
/// @{
virtual void InitSections();
virtual void EmitLabel(MCSymbol *Symbol);
virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment);
virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
assert(0 && "macho doesn't support this directive");
}
virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
assert(0 && "macho doesn't support this directive");
}
virtual void EmitCOFFSymbolType(int Type) {
assert(0 && "macho doesn't support this directive");
}
virtual void EndCOFFSymbolDef() {
assert(0 && "macho doesn't support this directive");
}
virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
assert(0 && "macho doesn't support this directive");
}
virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
assert(0 && "macho doesn't support this directive");
}
virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
unsigned Size = 0, unsigned ByteAlignment = 0);
virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment = 0);
virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
virtual void EmitValue(const MCExpr *Value, unsigned Size,unsigned AddrSpace);
virtual void EmitGPRel32Value(const MCExpr *Value) {
assert(0 && "macho doesn't support this directive");
}
virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
unsigned ValueSize = 1,
unsigned MaxBytesToEmit = 0);
virtual void EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit = 0);
virtual void EmitValueToOffset(const MCExpr *Offset,
unsigned char Value = 0);
virtual void EmitFileDirective(StringRef Filename) {
// FIXME: Just ignore the .file; it isn't important enough to fail the
// entire assembly.
//report_fatal_error("unsupported directive: '.file'");
}
virtual void EmitDwarfFileDirective(unsigned FileNo, StringRef Filename) {
// FIXME: Just ignore the .file; it isn't important enough to fail the
// entire assembly.
//report_fatal_error("unsupported directive: '.file'");
}
virtual void EmitInstruction(const MCInst &Inst);
virtual void Finish();
/// @}
};
} // end anonymous namespace.
void MCMachOStreamer::InitSections() {
SwitchSection(getContext().getMachOSection("__TEXT", "__text",
MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
0, SectionKind::getText()));
}
void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
// TODO: This is almost exactly the same as WinCOFFStreamer. Consider merging
// into MCObjectStreamer.
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
assert(CurSection && "Cannot emit before setting section!");
Symbol->setSection(*CurSection);
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
// We have to create a new fragment if this is an atom defining symbol,
// fragments cannot span atoms.
if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()))
new MCDataFragment(getCurrentSectionData());
// FIXME: This is wasteful, we don't necessarily need to create a data
// fragment. Instead, we should mark the symbol as pointing into the data
// fragment if it exists, otherwise we should just queue the label and set its
// fragment pointer when we emit the next fragment.
MCDataFragment *F = getOrCreateDataFragment();
assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
SD.setFragment(F);
SD.setOffset(F->getContents().size());
// This causes the reference type flag to be cleared. Darwin 'as' was "trying"
// to clear the weak reference and weak definition bits too, but the
// implementation was buggy. For now we just try to match 'as', for
// diffability.
//
// FIXME: Cleanup this code, these bits should be emitted based on semantic
// properties, not on the order of definition, etc.
SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
}
void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
switch (Flag) {
case MCAF_SubsectionsViaSymbols:
getAssembler().setSubsectionsViaSymbols(true);
return;
}
assert(0 && "invalid assembler flag!");
}
void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
// TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
// MCObjectStreamer.
// FIXME: Lift context changes into super class.
getAssembler().getOrCreateSymbolData(*Symbol);
Symbol->setVariableValue(AddValueSymbols(Value));
}
void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
MCSymbolAttr Attribute) {
// Indirect symbols are handled differently, to match how 'as' handles
// them. This makes writing matching .o files easier.
if (Attribute == MCSA_IndirectSymbol) {
// Note that we intentionally cannot use the symbol data here; this is
// important for matching the string table that 'as' generates.
IndirectSymbolData ISD;
ISD.Symbol = Symbol;
ISD.SectionData = getCurrentSectionData();
getAssembler().getIndirectSymbols().push_back(ISD);
return;
}
// Adding a symbol attribute always introduces the symbol, note that an
// important side effect of calling getOrCreateSymbolData here is to register
// the symbol with the assembler.
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
// The implementation of symbol attributes is designed to match 'as', but it
// leaves much to desired. It doesn't really make sense to arbitrarily add and
// remove flags, but 'as' allows this (in particular, see .desc).
//
// In the future it might be worth trying to make these operations more well
// defined.
switch (Attribute) {
case MCSA_Invalid:
case MCSA_ELF_TypeFunction:
case MCSA_ELF_TypeIndFunction:
case MCSA_ELF_TypeObject:
case MCSA_ELF_TypeTLS:
case MCSA_ELF_TypeCommon:
case MCSA_ELF_TypeNoType:
case MCSA_IndirectSymbol:
case MCSA_Hidden:
case MCSA_Internal:
case MCSA_Protected:
case MCSA_Weak:
case MCSA_Local:
assert(0 && "Invalid symbol attribute for Mach-O!");
break;
case MCSA_Global:
SD.setExternal(true);
// This effectively clears the undefined lazy bit, in Darwin 'as', although
// it isn't very consistent because it implements this as part of symbol
// lookup.
//
// FIXME: Cleanup this code, these bits should be emitted based on semantic
// properties, not on the order of definition, etc.
SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
break;
case MCSA_LazyReference:
// FIXME: This requires -dynamic.
SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
if (Symbol->isUndefined())
SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
break;
// Since .reference sets the no dead strip bit, it is equivalent to
// .no_dead_strip in practice.
case MCSA_Reference:
case MCSA_NoDeadStrip:
SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
break;
case MCSA_PrivateExtern:
SD.setExternal(true);
SD.setPrivateExtern(true);
break;
case MCSA_WeakReference:
// FIXME: This requires -dynamic.
if (Symbol->isUndefined())
SD.setFlags(SD.getFlags() | SF_WeakReference);
break;
case MCSA_WeakDefinition:
// FIXME: 'as' enforces that this is defined and global. The manual claims
// it has to be in a coalesced section, but this isn't enforced.
SD.setFlags(SD.getFlags() | SF_WeakDefinition);
break;
case MCSA_WeakDefAutoPrivate:
SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
break;
}
}
void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
// Encode the 'desc' value into the lowest implementation defined bits.
assert(DescValue == (DescValue & SF_DescFlagsMask) &&
"Invalid .desc value!");
getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
DescValue & SF_DescFlagsMask);
}
void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
// FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
SD.setExternal(true);
SD.setCommon(Size, ByteAlignment);
}
void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
unsigned Size, unsigned ByteAlignment) {
MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
// The symbol may not be present, which only creates the section.
if (!Symbol)
return;
// FIXME: Assert that this section has the zerofill type.
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
// Emit an align fragment if necessary.
if (ByteAlignment != 1)
new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
SD.setFragment(F);
Symbol->setSection(*Section);
// Update the maximum alignment on the zero fill section if necessary.
if (ByteAlignment > SectData.getAlignment())
SectData.setAlignment(ByteAlignment);
}
// This should always be called with the thread local bss section. Like the
// .zerofill directive this doesn't actually switch sections on us.
void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {
EmitZerofill(Section, Symbol, Size, ByteAlignment);
return;
}
void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
// TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
// MCObjectStreamer.
getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
}
void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {
// TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
// MCObjectStreamer.
MCDataFragment *DF = getOrCreateDataFragment();
// Avoid fixups when possible.
int64_t AbsValue;
if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
// FIXME: Endianness assumption.
for (unsigned i = 0; i != Size; ++i)
DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
} else {
DF->addFixup(MCFixup::Create(DF->getContents().size(),
AddValueSymbols(Value),
MCFixup::getKindForSize(Size)));
DF->getContents().resize(DF->getContents().size() + Size, 0);
}
}
void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
int64_t Value, unsigned ValueSize,
unsigned MaxBytesToEmit) {
// TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
// MCObjectStreamer.
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
getCurrentSectionData());
// Update the maximum alignment on the current section if necessary.
if (ByteAlignment > getCurrentSectionData()->getAlignment())
getCurrentSectionData()->setAlignment(ByteAlignment);
}
void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit) {
// TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
// MCObjectStreamer.
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
getCurrentSectionData());
F->setEmitNops(true);
// Update the maximum alignment on the current section if necessary.
if (ByteAlignment > getCurrentSectionData()->getAlignment())
getCurrentSectionData()->setAlignment(ByteAlignment);
}
void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
unsigned char Value) {
new MCOrgFragment(*Offset, Value, getCurrentSectionData());
}
void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
// Add the fixups and data.
//
// FIXME: Revisit this design decision when relaxation is done, we may be
// able to get away with not storing any extra data in the MCInst.
SmallVector<MCFixup, 4> Fixups;
SmallString<256> Code;
raw_svector_ostream VecOS(Code);
getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
VecOS.flush();
IF->getCode() = Code;
IF->getFixups() = Fixups;
}
void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
MCDataFragment *DF = getOrCreateDataFragment();
SmallVector<MCFixup, 4> Fixups;
SmallString<256> Code;
raw_svector_ostream VecOS(Code);
getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
VecOS.flush();
// Add the fixups and data.
for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
DF->addFixup(Fixups[i]);
}
DF->getContents().append(Code.begin(), Code.end());
}
void MCMachOStreamer::EmitInstruction(const MCInst &Inst) {
// Scan for values.
for (unsigned i = Inst.getNumOperands(); i--; )
if (Inst.getOperand(i).isExpr())
AddValueSymbols(Inst.getOperand(i).getExpr());
getCurrentSectionData()->setHasInstructions(true);
// Now that a machine instruction has been assembled into this section, make
// a line entry for any .loc directive that has been seen.
MakeLineEntryForSection(getCurrentSection());
// If this instruction doesn't need relaxation, just emit it as data.
if (!getAssembler().getBackend().MayNeedRelaxation(Inst)) {
EmitInstToData(Inst);
return;
}
// Otherwise, if we are relaxing everything, relax the instruction as much as
// possible and emit it as data.
if (getAssembler().getRelaxAll()) {
MCInst Relaxed;
getAssembler().getBackend().RelaxInstruction(Inst, Relaxed);
while (getAssembler().getBackend().MayNeedRelaxation(Relaxed))
getAssembler().getBackend().RelaxInstruction(Relaxed, Relaxed);
EmitInstToData(Relaxed);
return;
}
// Otherwise emit to a separate fragment.
EmitInstToFragment(Inst);
}
//
// This is called when an instruction is assembled into the specified section
// and if there is information from the last .loc directive that has yet to have
// a line entry made for it is made.
//
void MCMachOStreamer::MakeLineEntryForSection(const MCSection *Section) {
if (!getContext().getDwarfLocSeen())
return;
// Create a symbol at in the current section for use in the line entry.
MCSymbol *LineSym = getContext().CreateTempSymbol();
// Set the value of the symbol to use for the MCLineEntry.
EmitLabel(LineSym);
// Get the current .loc info saved in the context.
const MCDwarfLoc &DwarfLoc = getContext().getCurrentDwarfLoc();
// Create a (local) line entry with the symbol and the current .loc info.
MCLineEntry LineEntry(LineSym, DwarfLoc);
// clear DwarfLocSeen saying the current .loc info is now used.
getContext().clearDwarfLocSeen();
// Get the MCLineSection for this section, if one does not exist for this
// section create it.
DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
getContext().getMCLineSections();
MCLineSection *LineSection = MCLineSections[Section];
if (!LineSection) {
// Create a new MCLineSection. This will be deleted after the dwarf line
// table is created using it by iterating through the MCLineSections
// DenseMap.
LineSection = new MCLineSection;
// Save a pointer to the new LineSection into the MCLineSections DenseMap.
MCLineSections[Section] = LineSection;
}
// Add the line entry to this section's entries.
LineSection->addLineEntry(LineEntry);
}
//
// This helper routine returns an expression of End - Start + IntVal for use
// by EmitDwarfFileTable() below.
//
const MCExpr * MCMachOStreamer::MakeStartMinusEndExpr(MCSymbol *Start,
MCSymbol *End,
int IntVal) {
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *Res =
MCSymbolRefExpr::Create(End, Variant, getContext());
const MCExpr *RHS =
MCSymbolRefExpr::Create(Start, Variant, getContext());
const MCExpr *Res1 =
MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS,getContext());
const MCExpr *Res2 =
MCConstantExpr::Create(IntVal, getContext());
const MCExpr *Res3 =
MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, getContext());
return Res3;
}
//
// This emits the Dwarf file (and eventually the line) table.
//
void MCMachOStreamer::EmitDwarfFileTable(void) {
// For now make sure we don't put out the Dwarf file table if no .file
// directives were seen.
const std::vector<MCDwarfFile *> &MCDwarfFiles =
getContext().getMCDwarfFiles();
if (MCDwarfFiles.size() == 0)
return;
// This is the Mach-O section, for ELF it is the .debug_line section.
SwitchSection(getContext().getMachOSection("__DWARF", "__debug_line",
MCSectionMachO::S_ATTR_DEBUG,
0, SectionKind::getDataRelLocal()));
// Create a symbol at the beginning of this section.
MCSymbol *LineStartSym = getContext().CreateTempSymbol();
// Set the value of the symbol, as we are at the start of the section.
EmitLabel(LineStartSym);
// Create a symbol for the end of the section (to be set when we get there).
MCSymbol *LineEndSym = getContext().CreateTempSymbol();
// The first 4 bytes is the total length of the information for this
// compilation unit (not including these 4 bytes for the length).
EmitValue(MakeStartMinusEndExpr(LineStartSym, LineEndSym, 4), 4, 0);
// Next 2 bytes is the Version, which is Dwarf 2.
EmitIntValue(2, 2);
// Create a symbol for the end of the prologue (to be set when we get there).
MCSymbol *ProEndSym = getContext().CreateTempSymbol(); // Lprologue_end
// Length of the prologue, is the next 4 bytes. Which is the start of the
// section to the end of the prologue. Not including the 4 bytes for the
// total length, the 2 bytes for the version, and these 4 bytes for the
// length of the prologue.
EmitValue(MakeStartMinusEndExpr(LineStartSym, ProEndSym, (4 + 2 + 4)), 4, 0);
// Parameters of the state machine, are next.
// Define the architecture-dependent minimum instruction length (in
// bytes). This value should be rather too small than too big. */
// DWARF2_LINE_MIN_INSN_LENGTH
EmitIntValue(1, 1);
// Flag that indicates the initial value of the is_stmt_start flag.
// DWARF2_LINE_DEFAULT_IS_STMT
EmitIntValue(1, 1);
// Minimum line offset in a special line info. opcode. This value
// was chosen to give a reasonable range of values. */
// DWARF2_LINE_BASE
EmitIntValue(uint64_t(-5), 1);
// Range of line offsets in a special line info. opcode.
// DWARF2_LINE_RANGE
EmitIntValue(14, 1);
// First special line opcode - leave room for the standard opcodes.
// DWARF2_LINE_OPCODE_BASE
EmitIntValue(13, 1);
// Standard opcode lengths
EmitIntValue(0, 1); // length of DW_LNS_copy
EmitIntValue(1, 1); // length of DW_LNS_advance_pc
EmitIntValue(1, 1); // length of DW_LNS_advance_line
EmitIntValue(1, 1); // length of DW_LNS_set_file
EmitIntValue(1, 1); // length of DW_LNS_set_column
EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
EmitIntValue(1, 1); // DW_LNS_set_isa
// Put out the directory and file tables.
// First the directory table.
const std::vector<StringRef> &MCDwarfDirs =
getContext().getMCDwarfDirs();
for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
EmitBytes(StringRef("\0", 1), 0); // the null termination of the string
}
EmitIntValue(0, 1); // Terminate the directory list
// Second the file table.
for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
EmitBytes(StringRef("\0", 1), 0); // the null termination of the string
// FIXME the Directory number should be a .uleb128 not a .byte
EmitIntValue(MCDwarfFiles[i]->getDirIndex(), 1);
EmitIntValue(0, 1); // last modification timestamp (always 0)
EmitIntValue(0, 1); // filesize (always 0)
}
EmitIntValue(0, 1); // Terminate the file list
// This is the end of the prologue, so set the value of the symbol at the
// end of the prologue (that was used in a previous expression).
EmitLabel(ProEndSym);
// TODO: This is the point where the line tables would be emitted.
// Delete the MCLineSections that were created in
// MCMachOStreamer::MakeLineEntryForSection() and used to emit the line
// tables.
DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
getContext().getMCLineSections();
for (DenseMap<const MCSection *, MCLineSection *>::iterator it =
MCLineSections.begin(), ie = MCLineSections.end(); it != ie; ++it) {
delete it->second;
}
// If there are no line tables emited then we emit:
// The following DW_LNE_set_address sequence to set the address to zero
// TODO test for 32-bit or 64-bit output
// This is the sequence for 32-bit code
EmitIntValue(0, 1);
EmitIntValue(5, 1);
EmitIntValue(2, 1);
EmitIntValue(0, 1);
EmitIntValue(0, 1);
EmitIntValue(0, 1);
EmitIntValue(0, 1);
// Lastly emit the DW_LNE_end_sequence which consists of 3 bytes '00 01 01'
// (00 is the code for extended opcodes, followed by a ULEB128 length of the
// extended opcode (01), and the DW_LNE_end_sequence (01).
EmitIntValue(0, 1); // DW_LNS_extended_op
EmitIntValue(1, 1); // ULEB128 length of the extended opcode
EmitIntValue(1, 1); // DW_LNE_end_sequence
// This is the end of the section, so set the value of the symbol at the end
// of this section (that was used in a previous expression).
EmitLabel(LineEndSym);
}
void MCMachOStreamer::Finish() {
// Dump out the dwarf file and directory tables (soon to include line table)
EmitDwarfFileTable();
// We have to set the fragment atom associations so we can relax properly for
// Mach-O.
// First, scan the symbol table to build a lookup table from fragments to
// defining symbols.
DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
ie = getAssembler().symbol_end(); it != ie; ++it) {
if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
it->getFragment()) {
// An atom defining symbol should never be internal to a fragment.
assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
DefiningSymbolMap[it->getFragment()] = it;
}
}
// Set the fragment atom associations by tracking the last seen atom defining
// symbol.
for (MCAssembler::iterator it = getAssembler().begin(),
ie = getAssembler().end(); it != ie; ++it) {
MCSymbolData *CurrentAtom = 0;
for (MCSectionData::iterator it2 = it->begin(),
ie2 = it->end(); it2 != ie2; ++it2) {
if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
CurrentAtom = SD;
it2->setAtom(CurrentAtom);
}
}
this->MCObjectStreamer::Finish();
}
MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
raw_ostream &OS, MCCodeEmitter *CE,
bool RelaxAll) {
MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
if (RelaxAll)
S->getAssembler().setRelaxAll(true);
return S;
}