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/ADT/STLExtras.h"
12 #include "llvm/MC/MCAsmBackend.h"
13 #include "llvm/MC/MCAsmInfo.h"
14 #include "llvm/MC/MCAssembler.h"
15 #include "llvm/MC/MCCodeEmitter.h"
16 #include "llvm/MC/MCContext.h"
17 #include "llvm/MC/MCDwarf.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/MC/MCObjectWriter.h"
20 #include "llvm/MC/MCSection.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/Support/ErrorHandling.h"
25 MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
26 raw_ostream &OS, MCCodeEmitter *Emitter_)
27 : MCStreamer(Context),
28 Assembler(new MCAssembler(Context, TAB, *Emitter_,
29 *TAB.createObjectWriter(OS), OS)),
30 CurSectionData(nullptr), EmitEHFrame(true), EmitDebugFrame(false) {}
32 MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
33 raw_ostream &OS, MCCodeEmitter *Emitter_,
34 MCAssembler *_Assembler)
35 : MCStreamer(Context), Assembler(_Assembler), CurSectionData(nullptr),
36 EmitEHFrame(true), EmitDebugFrame(false) {}
38 MCObjectStreamer::~MCObjectStreamer() {
39 delete &Assembler->getBackend();
40 delete &Assembler->getEmitter();
41 delete &Assembler->getWriter();
45 void MCObjectStreamer::reset() {
48 CurSectionData = nullptr;
49 CurInsertionPoint = MCSectionData::iterator();
51 EmitDebugFrame = false;
55 void MCObjectStreamer::EmitFrames(MCAsmBackend *MAB) {
56 if (!getNumFrameInfos())
60 MCDwarfFrameEmitter::Emit(*this, MAB, true);
63 MCDwarfFrameEmitter::Emit(*this, MAB, false);
66 MCFragment *MCObjectStreamer::getCurrentFragment() const {
67 assert(getCurrentSectionData() && "No current section!");
69 if (CurInsertionPoint != getCurrentSectionData()->getFragmentList().begin())
70 return std::prev(CurInsertionPoint);
75 MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
76 MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
77 // When bundling is enabled, we don't want to add data to a fragment that
78 // already has instructions (see MCELFStreamer::EmitInstToData for details)
79 if (!F || (Assembler->isBundlingEnabled() && F->hasInstructions())) {
80 F = new MCDataFragment();
86 void MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
87 switch (Value->getKind()) {
89 cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
92 case MCExpr::Constant:
95 case MCExpr::Binary: {
96 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
97 AddValueSymbols(BE->getLHS());
98 AddValueSymbols(BE->getRHS());
102 case MCExpr::SymbolRef:
103 Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
107 AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
112 void MCObjectStreamer::EmitCFISections(bool EH, bool Debug) {
113 MCStreamer::EmitCFISections(EH, Debug);
115 EmitDebugFrame = Debug;
118 void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
120 MCDataFragment *DF = getOrCreateDataFragment();
122 MCLineEntry::Make(this, getCurrentSection().first);
124 // Avoid fixups when possible.
126 AddValueSymbols(Value);
127 if (Value->EvaluateAsAbsolute(AbsValue, getAssembler())) {
128 EmitIntValue(AbsValue, Size);
131 DF->getFixups().push_back(
132 MCFixup::Create(DF->getContents().size(), Value,
133 MCFixup::getKindForSize(Size, false), Loc));
134 DF->getContents().resize(DF->getContents().size() + Size, 0);
137 void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
138 // We need to create a local symbol to avoid relocations.
139 Frame.Begin = getContext().CreateTempSymbol();
140 EmitLabel(Frame.Begin);
143 void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
144 Frame.End = getContext().CreateTempSymbol();
145 EmitLabel(Frame.End);
148 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
149 MCStreamer::EmitLabel(Symbol);
151 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
153 // FIXME: This is wasteful, we don't necessarily need to create a data
154 // fragment. Instead, we should mark the symbol as pointing into the data
155 // fragment if it exists, otherwise we should just queue the label and set its
156 // fragment pointer when we emit the next fragment.
157 MCDataFragment *F = getOrCreateDataFragment();
158 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
160 SD.setOffset(F->getContents().size());
163 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
165 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
166 EmitULEB128IntValue(IntValue);
169 Value = ForceExpAbs(Value);
170 insert(new MCLEBFragment(*Value, false));
173 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
175 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
176 EmitSLEB128IntValue(IntValue);
179 Value = ForceExpAbs(Value);
180 insert(new MCLEBFragment(*Value, true));
183 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
184 const MCSymbol *Symbol) {
185 report_fatal_error("This file format doesn't support weak aliases.");
188 void MCObjectStreamer::ChangeSection(const MCSection *Section,
189 const MCExpr *Subsection) {
190 assert(Section && "Cannot switch to a null section!");
192 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
194 int64_t IntSubsection = 0;
196 !Subsection->EvaluateAsAbsolute(IntSubsection, getAssembler()))
197 report_fatal_error("Cannot evaluate subsection number");
198 if (IntSubsection < 0 || IntSubsection > 8192)
199 report_fatal_error("Subsection number out of range");
201 CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
204 void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
205 getAssembler().getOrCreateSymbolData(*Symbol);
206 AddValueSymbols(Value);
207 MCStreamer::EmitAssignment(Symbol, Value);
210 void MCObjectStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) {
212 for (unsigned i = Inst.getNumOperands(); i--; )
213 if (Inst.getOperand(i).isExpr())
214 AddValueSymbols(Inst.getOperand(i).getExpr());
216 MCSectionData *SD = getCurrentSectionData();
217 SD->setHasInstructions(true);
219 // Now that a machine instruction has been assembled into this section, make
220 // a line entry for any .loc directive that has been seen.
221 MCLineEntry::Make(this, getCurrentSection().first);
223 // If this instruction doesn't need relaxation, just emit it as data.
224 MCAssembler &Assembler = getAssembler();
225 if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
226 EmitInstToData(Inst, STI);
230 // Otherwise, relax and emit it as data if either:
231 // - The RelaxAll flag was passed
232 // - Bundling is enabled and this instruction is inside a bundle-locked
233 // group. We want to emit all such instructions into the same data
235 if (Assembler.getRelaxAll() ||
236 (Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
238 getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
239 while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
240 getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
241 EmitInstToData(Relaxed, STI);
245 // Otherwise emit to a separate fragment.
246 EmitInstToFragment(Inst, STI);
249 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
250 const MCSubtargetInfo &STI) {
251 // Always create a new, separate fragment here, because its size can change
252 // during relaxation.
253 MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
256 SmallString<128> Code;
257 raw_svector_ostream VecOS(Code);
258 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups(),
261 IF->getContents().append(Code.begin(), Code.end());
265 static const char *const BundlingNotImplementedMsg =
266 "Aligned bundling is not implemented for this object format";
269 void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
270 llvm_unreachable(BundlingNotImplementedMsg);
273 void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
274 llvm_unreachable(BundlingNotImplementedMsg);
277 void MCObjectStreamer::EmitBundleUnlock() {
278 llvm_unreachable(BundlingNotImplementedMsg);
281 void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
282 unsigned Column, unsigned Flags,
284 unsigned Discriminator,
285 StringRef FileName) {
286 // In case we see two .loc directives in a row, make sure the
287 // first one gets a line entry.
288 MCLineEntry::Make(this, getCurrentSection().first);
290 this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
291 Isa, Discriminator, FileName);
294 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
295 const MCSymbol *LastLabel,
296 const MCSymbol *Label,
297 unsigned PointerSize) {
299 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
302 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
304 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
305 MCDwarfLineAddr::Emit(this, LineDelta, Res);
308 AddrDelta = ForceExpAbs(AddrDelta);
309 insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
312 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
313 const MCSymbol *Label) {
314 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
316 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
317 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
320 AddrDelta = ForceExpAbs(AddrDelta);
321 insert(new MCDwarfCallFrameFragment(*AddrDelta));
324 void MCObjectStreamer::EmitBytes(StringRef Data) {
325 MCLineEntry::Make(this, getCurrentSection().first);
326 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
329 void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
332 unsigned MaxBytesToEmit) {
333 if (MaxBytesToEmit == 0)
334 MaxBytesToEmit = ByteAlignment;
335 insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
337 // Update the maximum alignment on the current section if necessary.
338 if (ByteAlignment > getCurrentSectionData()->getAlignment())
339 getCurrentSectionData()->setAlignment(ByteAlignment);
342 void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
343 unsigned MaxBytesToEmit) {
344 EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
345 cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
348 bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
349 unsigned char Value) {
351 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
352 insert(new MCOrgFragment(*Offset, Value));
356 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
357 EmitLabel(CurrentPos);
358 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
360 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
361 const MCExpr *Delta =
362 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
364 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
366 EmitFill(Res, Value);
370 // Associate GPRel32 fixup with data and resize data area
371 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
372 MCDataFragment *DF = getOrCreateDataFragment();
374 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
376 DF->getContents().resize(DF->getContents().size() + 4, 0);
379 // Associate GPRel32 fixup with data and resize data area
380 void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
381 MCDataFragment *DF = getOrCreateDataFragment();
383 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
385 DF->getContents().resize(DF->getContents().size() + 8, 0);
388 void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
389 // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
390 // problems evaluating expressions across multiple fragments.
391 getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
394 void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
395 unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
396 insert(new MCFillFragment(0, ItemSize, NumBytes));
399 void MCObjectStreamer::FinishImpl() {
400 // If we are generating dwarf for assembly source files dump out the sections.
401 if (getContext().getGenDwarfForAssembly())
402 MCGenDwarfInfo::Emit(this);
404 // Dump out the dwarf file & directory tables and line tables.
405 MCDwarfLineTable::Emit(this);
407 getAssembler().Finish();