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 // We need to create a local symbol to avoid relocations.
140 Frame.Begin = getContext().CreateTempSymbol();
141 EmitLabel(Frame.Begin);
144 void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
145 Frame.End = getContext().CreateTempSymbol();
146 EmitLabel(Frame.End);
149 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
150 MCStreamer::EmitLabel(Symbol);
152 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
154 // FIXME: This is wasteful, we don't necessarily need to create a data
155 // fragment. Instead, we should mark the symbol as pointing into the data
156 // fragment if it exists, otherwise we should just queue the label and set its
157 // fragment pointer when we emit the next fragment.
158 MCDataFragment *F = getOrCreateDataFragment();
159 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
161 SD.setOffset(F->getContents().size());
164 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
166 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
167 EmitULEB128IntValue(IntValue);
170 Value = ForceExpAbs(Value);
171 insert(new MCLEBFragment(*Value, false));
174 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
176 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
177 EmitSLEB128IntValue(IntValue);
180 Value = ForceExpAbs(Value);
181 insert(new MCLEBFragment(*Value, true));
184 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
185 const MCSymbol *Symbol) {
186 report_fatal_error("This file format doesn't support weak aliases.");
189 void MCObjectStreamer::ChangeSection(const MCSection *Section,
190 const MCExpr *Subsection) {
191 assert(Section && "Cannot switch to a null section!");
193 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
195 int64_t IntSubsection = 0;
197 !Subsection->EvaluateAsAbsolute(IntSubsection, getAssembler()))
198 report_fatal_error("Cannot evaluate subsection number");
199 if (IntSubsection < 0 || IntSubsection > 8192)
200 report_fatal_error("Subsection number out of range");
202 CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
205 void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
206 getAssembler().getOrCreateSymbolData(*Symbol);
207 AddValueSymbols(Value);
208 MCStreamer::EmitAssignment(Symbol, Value);
211 void MCObjectStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) {
213 for (unsigned i = Inst.getNumOperands(); i--; )
214 if (Inst.getOperand(i).isExpr())
215 AddValueSymbols(Inst.getOperand(i).getExpr());
217 MCSectionData *SD = getCurrentSectionData();
218 SD->setHasInstructions(true);
220 // Now that a machine instruction has been assembled into this section, make
221 // a line entry for any .loc directive that has been seen.
222 MCLineEntry::Make(this, getCurrentSection().first);
224 // If this instruction doesn't need relaxation, just emit it as data.
225 MCAssembler &Assembler = getAssembler();
226 if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
227 EmitInstToData(Inst, STI);
231 // Otherwise, relax and emit it as data if either:
232 // - The RelaxAll flag was passed
233 // - Bundling is enabled and this instruction is inside a bundle-locked
234 // group. We want to emit all such instructions into the same data
236 if (Assembler.getRelaxAll() ||
237 (Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
239 getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
240 while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
241 getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
242 EmitInstToData(Relaxed, STI);
246 // Otherwise emit to a separate fragment.
247 EmitInstToFragment(Inst, STI);
250 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
251 const MCSubtargetInfo &STI) {
252 // Always create a new, separate fragment here, because its size can change
253 // during relaxation.
254 MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
257 SmallString<128> Code;
258 raw_svector_ostream VecOS(Code);
259 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups(),
262 IF->getContents().append(Code.begin(), Code.end());
266 static const char *const BundlingNotImplementedMsg =
267 "Aligned bundling is not implemented for this object format";
270 void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
271 llvm_unreachable(BundlingNotImplementedMsg);
274 void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
275 llvm_unreachable(BundlingNotImplementedMsg);
278 void MCObjectStreamer::EmitBundleUnlock() {
279 llvm_unreachable(BundlingNotImplementedMsg);
282 void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
283 unsigned Column, unsigned Flags,
285 unsigned Discriminator,
286 StringRef FileName) {
287 // In case we see two .loc directives in a row, make sure the
288 // first one gets a line entry.
289 MCLineEntry::Make(this, getCurrentSection().first);
291 this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
292 Isa, Discriminator, FileName);
295 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
296 const MCSymbol *LastLabel,
297 const MCSymbol *Label,
298 unsigned PointerSize) {
300 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
303 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
305 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
306 MCDwarfLineAddr::Emit(this, LineDelta, Res);
309 AddrDelta = ForceExpAbs(AddrDelta);
310 insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
313 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
314 const MCSymbol *Label) {
315 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
317 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
318 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
321 AddrDelta = ForceExpAbs(AddrDelta);
322 insert(new MCDwarfCallFrameFragment(*AddrDelta));
325 void MCObjectStreamer::EmitBytes(StringRef Data) {
326 MCLineEntry::Make(this, getCurrentSection().first);
327 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
330 void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
333 unsigned MaxBytesToEmit) {
334 if (MaxBytesToEmit == 0)
335 MaxBytesToEmit = ByteAlignment;
336 insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
338 // Update the maximum alignment on the current section if necessary.
339 if (ByteAlignment > getCurrentSectionData()->getAlignment())
340 getCurrentSectionData()->setAlignment(ByteAlignment);
343 void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
344 unsigned MaxBytesToEmit) {
345 EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
346 cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
349 bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
350 unsigned char Value) {
352 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
353 insert(new MCOrgFragment(*Offset, Value));
357 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
358 EmitLabel(CurrentPos);
359 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
361 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
362 const MCExpr *Delta =
363 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
365 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
367 EmitFill(Res, Value);
371 // Associate GPRel32 fixup with data and resize data area
372 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
373 MCDataFragment *DF = getOrCreateDataFragment();
375 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
377 DF->getContents().resize(DF->getContents().size() + 4, 0);
380 // Associate GPRel32 fixup with data and resize data area
381 void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
382 MCDataFragment *DF = getOrCreateDataFragment();
384 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
386 DF->getContents().resize(DF->getContents().size() + 8, 0);
389 void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
390 // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
391 // problems evaluating expressions across multiple fragments.
392 getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
395 void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
396 unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
397 insert(new MCFillFragment(0, ItemSize, NumBytes));
400 void MCObjectStreamer::FinishImpl() {
401 // If we are generating dwarf for assembly source files dump out the sections.
402 if (getContext().getGenDwarfForAssembly())
403 MCGenDwarfInfo::Emit(this);
405 // Dump out the dwarf file & directory tables and line tables.
406 MCDwarfLineTable::Emit(this);
408 getAssembler().Finish();