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//===- lib/MC/MCStreamer.cpp - Streaming Machine Code 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/ADT/SmallString.h"
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/raw_ostream.h"
#include <cstdlib>
using namespace llvm;
MCStreamer::MCStreamer(StreamerKind Kind, MCContext &Ctx)
: Kind(Kind), Context(Ctx), EmitEHFrame(true), EmitDebugFrame(false),
CurrentW64UnwindInfo(0), LastSymbol(0), AutoInitSections(false) {
const MCSection *section = NULL;
SectionStack.push_back(std::make_pair(section, section));
}
MCStreamer::~MCStreamer() {
for (unsigned i = 0; i < getNumW64UnwindInfos(); ++i)
delete W64UnwindInfos[i];
}
void MCStreamer::reset() {
for (unsigned i = 0; i < getNumW64UnwindInfos(); ++i)
delete W64UnwindInfos[i];
EmitEHFrame = true;
EmitDebugFrame = false;
CurrentW64UnwindInfo = 0;
LastSymbol = 0;
const MCSection *section = NULL;
SectionStack.clear();
SectionStack.push_back(std::make_pair(section, section));
}
const MCExpr *MCStreamer::BuildSymbolDiff(MCContext &Context,
const MCSymbol *A,
const MCSymbol *B) {
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *ARef =
MCSymbolRefExpr::Create(A, Variant, Context);
const MCExpr *BRef =
MCSymbolRefExpr::Create(B, Variant, Context);
const MCExpr *AddrDelta =
MCBinaryExpr::Create(MCBinaryExpr::Sub, ARef, BRef, Context);
return AddrDelta;
}
const MCExpr *MCStreamer::ForceExpAbs(const MCExpr* Expr) {
if (Context.getAsmInfo().hasAggressiveSymbolFolding() ||
isa<MCSymbolRefExpr>(Expr))
return Expr;
MCSymbol *ABS = Context.CreateTempSymbol();
EmitAssignment(ABS, Expr);
return MCSymbolRefExpr::Create(ABS, Context);
}
raw_ostream &MCStreamer::GetCommentOS() {
// By default, discard comments.
return nulls();
}
void MCStreamer::EmitDwarfSetLineAddr(int64_t LineDelta,
const MCSymbol *Label, int PointerSize) {
// emit the sequence to set the address
EmitIntValue(dwarf::DW_LNS_extended_op, 1);
EmitULEB128IntValue(PointerSize + 1);
EmitIntValue(dwarf::DW_LNE_set_address, 1);
EmitSymbolValue(Label, PointerSize);
// emit the sequence for the LineDelta (from 1) and a zero address delta.
MCDwarfLineAddr::Emit(this, LineDelta, 0);
}
/// EmitIntValue - Special case of EmitValue that avoids the client having to
/// pass in a MCExpr for constant integers.
void MCStreamer::EmitIntValue(uint64_t Value, unsigned Size,
unsigned AddrSpace) {
assert(Size <= 8 && "Invalid size");
assert((isUIntN(8 * Size, Value) || isIntN(8 * Size, Value)) &&
"Invalid size");
char buf[8];
const bool isLittleEndian = Context.getAsmInfo().isLittleEndian();
for (unsigned i = 0; i != Size; ++i) {
unsigned index = isLittleEndian ? i : (Size - i - 1);
buf[i] = uint8_t(Value >> (index * 8));
}
EmitBytes(StringRef(buf, Size), AddrSpace);
}
/// EmitULEB128Value - Special case of EmitULEB128Value that avoids the
/// client having to pass in a MCExpr for constant integers.
void MCStreamer::EmitULEB128IntValue(uint64_t Value, unsigned Padding,
unsigned AddrSpace) {
SmallString<128> Tmp;
raw_svector_ostream OSE(Tmp);
encodeULEB128(Value, OSE, Padding);
EmitBytes(OSE.str(), AddrSpace);
}
/// EmitSLEB128Value - Special case of EmitSLEB128Value that avoids the
/// client having to pass in a MCExpr for constant integers.
void MCStreamer::EmitSLEB128IntValue(int64_t Value, unsigned AddrSpace) {
SmallString<128> Tmp;
raw_svector_ostream OSE(Tmp);
encodeSLEB128(Value, OSE);
EmitBytes(OSE.str(), AddrSpace);
}
void MCStreamer::EmitAbsValue(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {
const MCExpr *ABS = ForceExpAbs(Value);
EmitValue(ABS, Size, AddrSpace);
}
void MCStreamer::EmitValue(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {
EmitValueImpl(Value, Size, AddrSpace);
}
void MCStreamer::EmitSymbolValue(const MCSymbol *Sym, unsigned Size,
unsigned AddrSpace) {
EmitValueImpl(MCSymbolRefExpr::Create(Sym, getContext()), Size,
AddrSpace);
}
void MCStreamer::EmitGPRel64Value(const MCExpr *Value) {
report_fatal_error("unsupported directive in streamer");
}
void MCStreamer::EmitGPRel32Value(const MCExpr *Value) {
report_fatal_error("unsupported directive in streamer");
}
/// EmitFill - Emit NumBytes bytes worth of the value specified by
/// FillValue. This implements directives such as '.space'.
void MCStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
unsigned AddrSpace) {
const MCExpr *E = MCConstantExpr::Create(FillValue, getContext());
for (uint64_t i = 0, e = NumBytes; i != e; ++i)
EmitValue(E, 1, AddrSpace);
}
bool MCStreamer::EmitDwarfFileDirective(unsigned FileNo,
StringRef Directory,
StringRef Filename, unsigned CUID) {
return getContext().GetDwarfFile(Directory, Filename, FileNo, CUID) == 0;
}
void MCStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
unsigned Column, unsigned Flags,
unsigned Isa,
unsigned Discriminator,
StringRef FileName) {
getContext().setCurrentDwarfLoc(FileNo, Line, Column, Flags, Isa,
Discriminator);
}
MCDwarfFrameInfo *MCStreamer::getCurrentFrameInfo() {
if (FrameInfos.empty())
return NULL;
return &FrameInfos.back();
}
void MCStreamer::EnsureValidFrame() {
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
if (!CurFrame || CurFrame->End)
report_fatal_error("No open frame");
}
void MCStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
MCSymbol *EHSymbol) {
}
void MCStreamer::EmitLabel(MCSymbol *Symbol) {
assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
assert(getCurrentSection() && "Cannot emit before setting section!");
Symbol->setSection(*getCurrentSection());
LastSymbol = Symbol;
}
void MCStreamer::EmitDebugLabel(MCSymbol *Symbol) {
assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
assert(getCurrentSection() && "Cannot emit before setting section!");
Symbol->setSection(*getCurrentSection());
LastSymbol = Symbol;
}
void MCStreamer::EmitCompactUnwindEncoding(uint32_t CompactUnwindEncoding) {
EnsureValidFrame();
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->CompactUnwindEncoding = CompactUnwindEncoding;
}
void MCStreamer::EmitCFISections(bool EH, bool Debug) {
assert(EH || Debug);
EmitEHFrame = EH;
EmitDebugFrame = Debug;
}
void MCStreamer::EmitCFIStartProc() {
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
if (CurFrame && !CurFrame->End)
report_fatal_error("Starting a frame before finishing the previous one!");
MCDwarfFrameInfo Frame;
EmitCFIStartProcImpl(Frame);
FrameInfos.push_back(Frame);
}
void MCStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
}
void MCStreamer::RecordProcStart(MCDwarfFrameInfo &Frame) {
Frame.Function = LastSymbol;
// If the function is externally visible, we need to create a local
// symbol to avoid relocations.
StringRef Prefix = getContext().getAsmInfo().getPrivateGlobalPrefix();
if (LastSymbol && LastSymbol->getName().startswith(Prefix)) {
Frame.Begin = LastSymbol;
} else {
Frame.Begin = getContext().CreateTempSymbol();
EmitLabel(Frame.Begin);
}
}
void MCStreamer::EmitCFIEndProc() {
EnsureValidFrame();
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
EmitCFIEndProcImpl(*CurFrame);
}
void MCStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
}
void MCStreamer::RecordProcEnd(MCDwarfFrameInfo &Frame) {
Frame.End = getContext().CreateTempSymbol();
EmitLabel(Frame.End);
}
MCSymbol *MCStreamer::EmitCFICommon() {
EnsureValidFrame();
MCSymbol *Label = getContext().CreateTempSymbol();
EmitLabel(Label);
return Label;
}
void MCStreamer::EmitCFIDefCfa(int64_t Register, int64_t Offset) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createDefCfa(Label, Register, Offset);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIDefCfaOffset(int64_t Offset) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createDefCfaOffset(Label, Offset);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIAdjustCfaOffset(int64_t Adjustment) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createAdjustCfaOffset(Label, Adjustment);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIDefCfaRegister(int64_t Register) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createDefCfaRegister(Label, Register);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIOffset(int64_t Register, int64_t Offset) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createOffset(Label, Register, Offset);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIRelOffset(int64_t Register, int64_t Offset) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createRelOffset(Label, Register, Offset);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIPersonality(const MCSymbol *Sym,
unsigned Encoding) {
EnsureValidFrame();
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Personality = Sym;
CurFrame->PersonalityEncoding = Encoding;
}
void MCStreamer::EmitCFILsda(const MCSymbol *Sym, unsigned Encoding) {
EnsureValidFrame();
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Lsda = Sym;
CurFrame->LsdaEncoding = Encoding;
}
void MCStreamer::EmitCFIRememberState() {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction = MCCFIInstruction::createRememberState(Label);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIRestoreState() {
// FIXME: Error if there is no matching cfi_remember_state.
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction = MCCFIInstruction::createRestoreState(Label);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFISameValue(int64_t Register) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createSameValue(Label, Register);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIRestore(int64_t Register) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createRestore(Label, Register);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIEscape(StringRef Values) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction = MCCFIInstruction::createEscape(Label, Values);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFISignalFrame() {
EnsureValidFrame();
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->IsSignalFrame = true;
}
void MCStreamer::EmitCFIUndefined(int64_t Register) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createUndefined(Label, Register);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::EmitCFIRegister(int64_t Register1, int64_t Register2) {
MCSymbol *Label = EmitCFICommon();
MCCFIInstruction Instruction =
MCCFIInstruction::createRegister(Label, Register1, Register2);
MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
CurFrame->Instructions.push_back(Instruction);
}
void MCStreamer::setCurrentW64UnwindInfo(MCWin64EHUnwindInfo *Frame) {
W64UnwindInfos.push_back(Frame);
CurrentW64UnwindInfo = W64UnwindInfos.back();
}
void MCStreamer::EnsureValidW64UnwindInfo() {
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (!CurFrame || CurFrame->End)
report_fatal_error("No open Win64 EH frame function!");
}
void MCStreamer::EmitWin64EHStartProc(const MCSymbol *Symbol) {
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (CurFrame && !CurFrame->End)
report_fatal_error("Starting a function before ending the previous one!");
MCWin64EHUnwindInfo *Frame = new MCWin64EHUnwindInfo;
Frame->Begin = getContext().CreateTempSymbol();
Frame->Function = Symbol;
EmitLabel(Frame->Begin);
setCurrentW64UnwindInfo(Frame);
}
void MCStreamer::EmitWin64EHEndProc() {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (CurFrame->ChainedParent)
report_fatal_error("Not all chained regions terminated!");
CurFrame->End = getContext().CreateTempSymbol();
EmitLabel(CurFrame->End);
}
void MCStreamer::EmitWin64EHStartChained() {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *Frame = new MCWin64EHUnwindInfo;
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
Frame->Begin = getContext().CreateTempSymbol();
Frame->Function = CurFrame->Function;
Frame->ChainedParent = CurFrame;
EmitLabel(Frame->Begin);
setCurrentW64UnwindInfo(Frame);
}
void MCStreamer::EmitWin64EHEndChained() {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (!CurFrame->ChainedParent)
report_fatal_error("End of a chained region outside a chained region!");
CurFrame->End = getContext().CreateTempSymbol();
EmitLabel(CurFrame->End);
CurrentW64UnwindInfo = CurFrame->ChainedParent;
}
void MCStreamer::EmitWin64EHHandler(const MCSymbol *Sym, bool Unwind,
bool Except) {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (CurFrame->ChainedParent)
report_fatal_error("Chained unwind areas can't have handlers!");
CurFrame->ExceptionHandler = Sym;
if (!Except && !Unwind)
report_fatal_error("Don't know what kind of handler this is!");
if (Unwind)
CurFrame->HandlesUnwind = true;
if (Except)
CurFrame->HandlesExceptions = true;
}
void MCStreamer::EmitWin64EHHandlerData() {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (CurFrame->ChainedParent)
report_fatal_error("Chained unwind areas can't have handlers!");
}
void MCStreamer::EmitWin64EHPushReg(unsigned Register) {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
MCSymbol *Label = getContext().CreateTempSymbol();
MCWin64EHInstruction Inst(Win64EH::UOP_PushNonVol, Label, Register);
EmitLabel(Label);
CurFrame->Instructions.push_back(Inst);
}
void MCStreamer::EmitWin64EHSetFrame(unsigned Register, unsigned Offset) {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (CurFrame->LastFrameInst >= 0)
report_fatal_error("Frame register and offset already specified!");
if (Offset & 0x0F)
report_fatal_error("Misaligned frame pointer offset!");
MCWin64EHInstruction Inst(Win64EH::UOP_SetFPReg, NULL, Register, Offset);
CurFrame->LastFrameInst = CurFrame->Instructions.size();
CurFrame->Instructions.push_back(Inst);
}
void MCStreamer::EmitWin64EHAllocStack(unsigned Size) {
EnsureValidW64UnwindInfo();
if (Size & 7)
report_fatal_error("Misaligned stack allocation!");
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
MCSymbol *Label = getContext().CreateTempSymbol();
MCWin64EHInstruction Inst(Label, Size);
EmitLabel(Label);
CurFrame->Instructions.push_back(Inst);
}
void MCStreamer::EmitWin64EHSaveReg(unsigned Register, unsigned Offset) {
EnsureValidW64UnwindInfo();
if (Offset & 7)
report_fatal_error("Misaligned saved register offset!");
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
MCSymbol *Label = getContext().CreateTempSymbol();
MCWin64EHInstruction Inst(
Offset > 512*1024-8 ? Win64EH::UOP_SaveNonVolBig : Win64EH::UOP_SaveNonVol,
Label, Register, Offset);
EmitLabel(Label);
CurFrame->Instructions.push_back(Inst);
}
void MCStreamer::EmitWin64EHSaveXMM(unsigned Register, unsigned Offset) {
EnsureValidW64UnwindInfo();
if (Offset & 0x0F)
report_fatal_error("Misaligned saved vector register offset!");
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
MCSymbol *Label = getContext().CreateTempSymbol();
MCWin64EHInstruction Inst(
Offset > 512*1024-16 ? Win64EH::UOP_SaveXMM128Big : Win64EH::UOP_SaveXMM128,
Label, Register, Offset);
EmitLabel(Label);
CurFrame->Instructions.push_back(Inst);
}
void MCStreamer::EmitWin64EHPushFrame(bool Code) {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
if (CurFrame->Instructions.size() > 0)
report_fatal_error("If present, PushMachFrame must be the first UOP");
MCSymbol *Label = getContext().CreateTempSymbol();
MCWin64EHInstruction Inst(Win64EH::UOP_PushMachFrame, Label, Code);
EmitLabel(Label);
CurFrame->Instructions.push_back(Inst);
}
void MCStreamer::EmitWin64EHEndProlog() {
EnsureValidW64UnwindInfo();
MCWin64EHUnwindInfo *CurFrame = CurrentW64UnwindInfo;
CurFrame->PrologEnd = getContext().CreateTempSymbol();
EmitLabel(CurFrame->PrologEnd);
}
void MCStreamer::EmitCOFFSecRel32(MCSymbol const *Symbol) {
llvm_unreachable("This file format doesn't support this directive");
}
void MCStreamer::EmitFnStart() {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitFnEnd() {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitCantUnwind() {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitHandlerData() {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitPersonality(const MCSymbol *Personality) {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitSetFP(unsigned FpReg, unsigned SpReg, int64_t Offset) {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitPad(int64_t Offset) {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitRegSave(const SmallVectorImpl<unsigned> &RegList, bool) {
errs() << "Not implemented yet\n";
abort();
}
void MCStreamer::EmitTCEntry(const MCSymbol &S) {
llvm_unreachable("Unsupported method");
}
/// EmitRawText - If this file is backed by an assembly streamer, this dumps
/// the specified string in the output .s file. This capability is
/// indicated by the hasRawTextSupport() predicate.
void MCStreamer::EmitRawText(StringRef String) {
errs() << "EmitRawText called on an MCStreamer that doesn't support it, "
" something must not be fully mc'ized\n";
abort();
}
void MCStreamer::EmitRawText(const Twine &T) {
SmallString<128> Str;
T.toVector(Str);
EmitRawText(Str.str());
}
void MCStreamer::EmitFrames(bool usingCFI) {
if (!getNumFrameInfos())
return;
if (EmitEHFrame)
MCDwarfFrameEmitter::Emit(*this, usingCFI, true);
if (EmitDebugFrame)
MCDwarfFrameEmitter::Emit(*this, usingCFI, false);
}
void MCStreamer::EmitW64Tables() {
if (!getNumW64UnwindInfos())
return;
MCWin64EHUnwindEmitter::Emit(*this);
}
void MCStreamer::Finish() {
if (!FrameInfos.empty() && !FrameInfos.back().End)
report_fatal_error("Unfinished frame!");
FinishImpl();
}
MCSymbolData &MCStreamer::getOrCreateSymbolData(MCSymbol *Symbol) {
report_fatal_error("Not supported!");
return *(static_cast<MCSymbolData*> (NULL));
}