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 const MCExpr *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());
114 void MCObjectStreamer::EmitCFISections(bool EH, bool Debug) {
115 MCStreamer::EmitCFISections(EH, Debug);
117 EmitDebugFrame = Debug;
120 void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
122 MCDataFragment *DF = getOrCreateDataFragment();
124 MCLineEntry::Make(this, getCurrentSection().first);
126 // Avoid fixups when possible.
128 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
129 EmitIntValue(AbsValue, Size);
132 DF->getFixups().push_back(
133 MCFixup::Create(DF->getContents().size(), Value,
134 MCFixup::getKindForSize(Size, false), Loc));
135 DF->getContents().resize(DF->getContents().size() + Size, 0);
138 void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
139 RecordProcStart(Frame);
142 void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
143 RecordProcEnd(Frame);
146 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
147 MCStreamer::EmitLabel(Symbol);
149 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
151 // FIXME: This is wasteful, we don't necessarily need to create a data
152 // fragment. Instead, we should mark the symbol as pointing into the data
153 // fragment if it exists, otherwise we should just queue the label and set its
154 // fragment pointer when we emit the next fragment.
155 MCDataFragment *F = getOrCreateDataFragment();
156 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
158 SD.setOffset(F->getContents().size());
161 void MCObjectStreamer::EmitDebugLabel(MCSymbol *Symbol) {
165 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
167 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
168 EmitULEB128IntValue(IntValue);
171 Value = ForceExpAbs(Value);
172 insert(new MCLEBFragment(*Value, false));
175 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
177 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
178 EmitSLEB128IntValue(IntValue);
181 Value = ForceExpAbs(Value);
182 insert(new MCLEBFragment(*Value, true));
185 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
186 const MCSymbol *Symbol) {
187 report_fatal_error("This file format doesn't support weak aliases.");
190 void MCObjectStreamer::ChangeSection(const MCSection *Section,
191 const MCExpr *Subsection) {
192 assert(Section && "Cannot switch to a null section!");
194 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
196 int64_t IntSubsection = 0;
198 !Subsection->EvaluateAsAbsolute(IntSubsection, getAssembler()))
199 report_fatal_error("Cannot evaluate subsection number");
200 if (IntSubsection < 0 || IntSubsection > 8192)
201 report_fatal_error("Subsection number out of range");
203 CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
206 void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
207 getAssembler().getOrCreateSymbolData(*Symbol);
208 AddValueSymbols(Value);
209 MCStreamer::EmitAssignment(Symbol, Value);
212 void MCObjectStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) {
214 for (unsigned i = Inst.getNumOperands(); i--; )
215 if (Inst.getOperand(i).isExpr())
216 AddValueSymbols(Inst.getOperand(i).getExpr());
218 MCSectionData *SD = getCurrentSectionData();
219 SD->setHasInstructions(true);
221 // Now that a machine instruction has been assembled into this section, make
222 // a line entry for any .loc directive that has been seen.
223 MCLineEntry::Make(this, getCurrentSection().first);
225 // If this instruction doesn't need relaxation, just emit it as data.
226 MCAssembler &Assembler = getAssembler();
227 if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
228 EmitInstToData(Inst, STI);
232 // Otherwise, relax and emit it as data if either:
233 // - The RelaxAll flag was passed
234 // - Bundling is enabled and this instruction is inside a bundle-locked
235 // group. We want to emit all such instructions into the same data
237 if (Assembler.getRelaxAll() ||
238 (Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
240 getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
241 while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
242 getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
243 EmitInstToData(Relaxed, STI);
247 // Otherwise emit to a separate fragment.
248 EmitInstToFragment(Inst, STI);
251 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
252 const MCSubtargetInfo &STI) {
253 // Always create a new, separate fragment here, because its size can change
254 // during relaxation.
255 MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
258 SmallString<128> Code;
259 raw_svector_ostream VecOS(Code);
260 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups(),
263 IF->getContents().append(Code.begin(), Code.end());
267 static const char *const BundlingNotImplementedMsg =
268 "Aligned bundling is not implemented for this object format";
271 void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
272 llvm_unreachable(BundlingNotImplementedMsg);
275 void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
276 llvm_unreachable(BundlingNotImplementedMsg);
279 void MCObjectStreamer::EmitBundleUnlock() {
280 llvm_unreachable(BundlingNotImplementedMsg);
283 void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
284 unsigned Column, unsigned Flags,
286 unsigned Discriminator,
287 StringRef FileName) {
288 // In case we see two .loc directives in a row, make sure the
289 // first one gets a line entry.
290 MCLineEntry::Make(this, getCurrentSection().first);
292 this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
293 Isa, Discriminator, FileName);
296 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
297 const MCSymbol *LastLabel,
298 const MCSymbol *Label,
299 unsigned PointerSize) {
301 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
304 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
306 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
307 MCDwarfLineAddr::Emit(this, LineDelta, Res);
310 AddrDelta = ForceExpAbs(AddrDelta);
311 insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
314 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
315 const MCSymbol *Label) {
316 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
318 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
319 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
322 AddrDelta = ForceExpAbs(AddrDelta);
323 insert(new MCDwarfCallFrameFragment(*AddrDelta));
326 void MCObjectStreamer::EmitBytes(StringRef Data) {
327 MCLineEntry::Make(this, getCurrentSection().first);
328 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
331 void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
334 unsigned MaxBytesToEmit) {
335 if (MaxBytesToEmit == 0)
336 MaxBytesToEmit = ByteAlignment;
337 insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
339 // Update the maximum alignment on the current section if necessary.
340 if (ByteAlignment > getCurrentSectionData()->getAlignment())
341 getCurrentSectionData()->setAlignment(ByteAlignment);
344 void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
345 unsigned MaxBytesToEmit) {
346 EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
347 cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
350 bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
351 unsigned char Value) {
353 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
354 insert(new MCOrgFragment(*Offset, Value));
358 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
359 EmitLabel(CurrentPos);
360 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
362 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
363 const MCExpr *Delta =
364 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
366 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
368 EmitFill(Res, Value);
372 // Associate GPRel32 fixup with data and resize data area
373 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
374 MCDataFragment *DF = getOrCreateDataFragment();
376 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
378 DF->getContents().resize(DF->getContents().size() + 4, 0);
381 // Associate GPRel32 fixup with data and resize data area
382 void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
383 MCDataFragment *DF = getOrCreateDataFragment();
385 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
387 DF->getContents().resize(DF->getContents().size() + 8, 0);
390 void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
391 // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
392 // problems evaluating expressions across multiple fragments.
393 getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
396 void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
397 unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
398 insert(new MCFillFragment(0, ItemSize, NumBytes));
401 void MCObjectStreamer::FinishImpl() {
402 // If we are generating dwarf for assembly source files dump out the sections.
403 if (getContext().getGenDwarfForAssembly())
404 MCGenDwarfInfo::Emit(this);
406 // Dump out the dwarf file & directory tables and line tables.
407 MCDwarfLineTable::Emit(this);
409 getAssembler().Finish();