1 //===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/MC/MCObjectStreamer.h"
11 #include "llvm/MC/MCAsmBackend.h"
12 #include "llvm/MC/MCAsmInfo.h"
13 #include "llvm/MC/MCAssembler.h"
14 #include "llvm/MC/MCCodeEmitter.h"
15 #include "llvm/MC/MCContext.h"
16 #include "llvm/MC/MCDwarf.h"
17 #include "llvm/MC/MCExpr.h"
18 #include "llvm/MC/MCObjectWriter.h"
19 #include "llvm/MC/MCSymbol.h"
20 #include "llvm/Support/ErrorHandling.h"
23 MCObjectStreamer::MCObjectStreamer(StreamerKind Kind, MCContext &Context,
24 MCAsmBackend &TAB, raw_ostream &OS,
25 MCCodeEmitter *Emitter_)
26 : MCStreamer(Kind, Context),
27 Assembler(new MCAssembler(Context, TAB, *Emitter_,
28 *TAB.createObjectWriter(OS), OS)),
31 MCObjectStreamer::MCObjectStreamer(StreamerKind Kind, MCContext &Context,
32 MCAsmBackend &TAB, raw_ostream &OS,
33 MCCodeEmitter *Emitter_,
34 MCAssembler *_Assembler)
35 : MCStreamer(Kind, Context), Assembler(_Assembler), CurSectionData(0) {}
37 MCObjectStreamer::~MCObjectStreamer() {
38 delete &Assembler->getBackend();
39 delete &Assembler->getEmitter();
40 delete &Assembler->getWriter();
44 void MCObjectStreamer::reset() {
51 MCFragment *MCObjectStreamer::getCurrentFragment() const {
52 assert(getCurrentSectionData() && "No current section!");
54 if (!getCurrentSectionData()->empty())
55 return &getCurrentSectionData()->getFragmentList().back();
60 MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
61 MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
62 // When bundling is enabled, we don't want to add data to a fragment that
63 // already has instructions (see MCELFStreamer::EmitInstToData for details)
64 if (!F || (Assembler->isBundlingEnabled() && F->hasInstructions()))
65 F = new MCDataFragment(getCurrentSectionData());
69 const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
70 switch (Value->getKind()) {
72 cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
75 case MCExpr::Constant:
78 case MCExpr::Binary: {
79 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
80 AddValueSymbols(BE->getLHS());
81 AddValueSymbols(BE->getRHS());
85 case MCExpr::SymbolRef:
86 Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
90 AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
97 void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
99 assert(AddrSpace == 0 && "Address space must be 0!");
100 MCDataFragment *DF = getOrCreateDataFragment();
102 // Avoid fixups when possible.
104 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
105 EmitIntValue(AbsValue, Size, AddrSpace);
108 DF->getFixups().push_back(
109 MCFixup::Create(DF->getContents().size(), Value,
110 MCFixup::getKindForSize(Size, false)));
111 DF->getContents().resize(DF->getContents().size() + Size, 0);
114 void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
115 RecordProcStart(Frame);
118 void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
119 RecordProcEnd(Frame);
122 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
123 MCStreamer::EmitLabel(Symbol);
125 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
127 // FIXME: This is wasteful, we don't necessarily need to create a data
128 // fragment. Instead, we should mark the symbol as pointing into the data
129 // fragment if it exists, otherwise we should just queue the label and set its
130 // fragment pointer when we emit the next fragment.
131 MCDataFragment *F = getOrCreateDataFragment();
132 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
134 SD.setOffset(F->getContents().size());
137 void MCObjectStreamer::EmitDebugLabel(MCSymbol *Symbol) {
141 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
143 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
144 EmitULEB128IntValue(IntValue);
147 Value = ForceExpAbs(Value);
148 new MCLEBFragment(*Value, false, getCurrentSectionData());
151 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
153 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
154 EmitSLEB128IntValue(IntValue);
157 Value = ForceExpAbs(Value);
158 new MCLEBFragment(*Value, true, getCurrentSectionData());
161 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
162 const MCSymbol *Symbol) {
163 report_fatal_error("This file format doesn't support weak aliases.");
166 void MCObjectStreamer::ChangeSection(const MCSection *Section) {
167 assert(Section && "Cannot switch to a null section!");
169 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
172 void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
173 getAssembler().getOrCreateSymbolData(*Symbol);
174 Symbol->setVariableValue(AddValueSymbols(Value));
177 void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
179 for (unsigned i = Inst.getNumOperands(); i--; )
180 if (Inst.getOperand(i).isExpr())
181 AddValueSymbols(Inst.getOperand(i).getExpr());
183 MCSectionData *SD = getCurrentSectionData();
184 SD->setHasInstructions(true);
186 // Now that a machine instruction has been assembled into this section, make
187 // a line entry for any .loc directive that has been seen.
188 MCLineEntry::Make(this, getCurrentSection());
190 // If this instruction doesn't need relaxation, just emit it as data.
191 MCAssembler &Assembler = getAssembler();
192 if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
193 EmitInstToData(Inst);
197 // Otherwise, relax and emit it as data if either:
198 // - The RelaxAll flag was passed
199 // - Bundling is enabled and this instruction is inside a bundle-locked
200 // group. We want to emit all such instructions into the same data
202 if (Assembler.getRelaxAll() ||
203 (Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
205 getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
206 while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
207 getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
208 EmitInstToData(Relaxed);
212 // Otherwise emit to a separate fragment.
213 EmitInstToFragment(Inst);
216 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
217 // Always create a new, separate fragment here, because its size can change
218 // during relaxation.
219 MCRelaxableFragment *IF =
220 new MCRelaxableFragment(Inst, getCurrentSectionData());
222 SmallString<128> Code;
223 raw_svector_ostream VecOS(Code);
224 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
226 IF->getContents().append(Code.begin(), Code.end());
230 static const char *BundlingNotImplementedMsg =
231 "Aligned bundling is not implemented for this object format";
234 void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
235 llvm_unreachable(BundlingNotImplementedMsg);
238 void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
239 llvm_unreachable(BundlingNotImplementedMsg);
242 void MCObjectStreamer::EmitBundleUnlock() {
243 llvm_unreachable(BundlingNotImplementedMsg);
246 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
247 const MCSymbol *LastLabel,
248 const MCSymbol *Label,
249 unsigned PointerSize) {
251 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
254 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
256 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
257 MCDwarfLineAddr::Emit(this, LineDelta, Res);
260 AddrDelta = ForceExpAbs(AddrDelta);
261 new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
264 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
265 const MCSymbol *Label) {
266 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
268 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
269 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
272 AddrDelta = ForceExpAbs(AddrDelta);
273 new MCDwarfCallFrameFragment(*AddrDelta, getCurrentSectionData());
276 void MCObjectStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
277 assert(AddrSpace == 0 && "Address space must be 0!");
278 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
281 void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
284 unsigned MaxBytesToEmit) {
285 if (MaxBytesToEmit == 0)
286 MaxBytesToEmit = ByteAlignment;
287 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
288 getCurrentSectionData());
290 // Update the maximum alignment on the current section if necessary.
291 if (ByteAlignment > getCurrentSectionData()->getAlignment())
292 getCurrentSectionData()->setAlignment(ByteAlignment);
295 void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
296 unsigned MaxBytesToEmit) {
297 EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
298 cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
301 bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
302 unsigned char Value) {
304 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
305 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
309 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
310 EmitLabel(CurrentPos);
311 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
313 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
314 const MCExpr *Delta =
315 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
317 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
319 EmitFill(Res, Value);
323 // Associate GPRel32 fixup with data and resize data area
324 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
325 MCDataFragment *DF = getOrCreateDataFragment();
327 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
329 DF->getContents().resize(DF->getContents().size() + 4, 0);
332 // Associate GPRel32 fixup with data and resize data area
333 void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
334 MCDataFragment *DF = getOrCreateDataFragment();
336 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
338 DF->getContents().resize(DF->getContents().size() + 8, 0);
341 void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
342 unsigned AddrSpace) {
343 assert(AddrSpace == 0 && "Address space must be 0!");
344 // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
345 // problems evaluating expressions across multiple fragments.
346 getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
349 void MCObjectStreamer::FinishImpl() {
350 // Dump out the dwarf file & directory tables and line tables.
351 const MCSymbol *LineSectionSymbol = NULL;
352 if (getContext().hasDwarfFiles())
353 LineSectionSymbol = MCDwarfFileTable::Emit(this);
355 // If we are generating dwarf for assembly source files dump out the sections.
356 if (getContext().getGenDwarfForAssembly())
357 MCGenDwarfInfo::Emit(this, LineSectionSymbol);
359 getAssembler().Finish();