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::EmitULEB128Value(const MCExpr *Value) {
163 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
164 EmitULEB128IntValue(IntValue);
167 Value = ForceExpAbs(Value);
168 insert(new MCLEBFragment(*Value, false));
171 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
173 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
174 EmitSLEB128IntValue(IntValue);
177 Value = ForceExpAbs(Value);
178 insert(new MCLEBFragment(*Value, true));
181 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
182 const MCSymbol *Symbol) {
183 report_fatal_error("This file format doesn't support weak aliases.");
186 void MCObjectStreamer::ChangeSection(const MCSection *Section,
187 const MCExpr *Subsection) {
188 assert(Section && "Cannot switch to a null section!");
190 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
192 int64_t IntSubsection = 0;
194 !Subsection->EvaluateAsAbsolute(IntSubsection, getAssembler()))
195 report_fatal_error("Cannot evaluate subsection number");
196 if (IntSubsection < 0 || IntSubsection > 8192)
197 report_fatal_error("Subsection number out of range");
199 CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
202 void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
203 getAssembler().getOrCreateSymbolData(*Symbol);
204 AddValueSymbols(Value);
205 MCStreamer::EmitAssignment(Symbol, Value);
208 void MCObjectStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) {
210 for (unsigned i = Inst.getNumOperands(); i--; )
211 if (Inst.getOperand(i).isExpr())
212 AddValueSymbols(Inst.getOperand(i).getExpr());
214 MCSectionData *SD = getCurrentSectionData();
215 SD->setHasInstructions(true);
217 // Now that a machine instruction has been assembled into this section, make
218 // a line entry for any .loc directive that has been seen.
219 MCLineEntry::Make(this, getCurrentSection().first);
221 // If this instruction doesn't need relaxation, just emit it as data.
222 MCAssembler &Assembler = getAssembler();
223 if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
224 EmitInstToData(Inst, STI);
228 // Otherwise, relax and emit it as data if either:
229 // - The RelaxAll flag was passed
230 // - Bundling is enabled and this instruction is inside a bundle-locked
231 // group. We want to emit all such instructions into the same data
233 if (Assembler.getRelaxAll() ||
234 (Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
236 getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
237 while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
238 getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
239 EmitInstToData(Relaxed, STI);
243 // Otherwise emit to a separate fragment.
244 EmitInstToFragment(Inst, STI);
247 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
248 const MCSubtargetInfo &STI) {
249 // Always create a new, separate fragment here, because its size can change
250 // during relaxation.
251 MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
254 SmallString<128> Code;
255 raw_svector_ostream VecOS(Code);
256 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups(),
259 IF->getContents().append(Code.begin(), Code.end());
263 static const char *const BundlingNotImplementedMsg =
264 "Aligned bundling is not implemented for this object format";
267 void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
268 llvm_unreachable(BundlingNotImplementedMsg);
271 void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
272 llvm_unreachable(BundlingNotImplementedMsg);
275 void MCObjectStreamer::EmitBundleUnlock() {
276 llvm_unreachable(BundlingNotImplementedMsg);
279 void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
280 unsigned Column, unsigned Flags,
282 unsigned Discriminator,
283 StringRef FileName) {
284 // In case we see two .loc directives in a row, make sure the
285 // first one gets a line entry.
286 MCLineEntry::Make(this, getCurrentSection().first);
288 this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
289 Isa, Discriminator, FileName);
292 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
293 const MCSymbol *LastLabel,
294 const MCSymbol *Label,
295 unsigned PointerSize) {
297 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
300 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
302 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
303 MCDwarfLineAddr::Emit(this, LineDelta, Res);
306 AddrDelta = ForceExpAbs(AddrDelta);
307 insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
310 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
311 const MCSymbol *Label) {
312 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
314 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
315 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
318 AddrDelta = ForceExpAbs(AddrDelta);
319 insert(new MCDwarfCallFrameFragment(*AddrDelta));
322 void MCObjectStreamer::EmitBytes(StringRef Data) {
323 MCLineEntry::Make(this, getCurrentSection().first);
324 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
327 void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
330 unsigned MaxBytesToEmit) {
331 if (MaxBytesToEmit == 0)
332 MaxBytesToEmit = ByteAlignment;
333 insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
335 // Update the maximum alignment on the current section if necessary.
336 if (ByteAlignment > getCurrentSectionData()->getAlignment())
337 getCurrentSectionData()->setAlignment(ByteAlignment);
340 void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
341 unsigned MaxBytesToEmit) {
342 EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
343 cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
346 bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
347 unsigned char Value) {
349 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
350 insert(new MCOrgFragment(*Offset, Value));
354 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
355 EmitLabel(CurrentPos);
356 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
358 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
359 const MCExpr *Delta =
360 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
362 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
364 EmitFill(Res, Value);
368 // Associate GPRel32 fixup with data and resize data area
369 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
370 MCDataFragment *DF = getOrCreateDataFragment();
372 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
374 DF->getContents().resize(DF->getContents().size() + 4, 0);
377 // Associate GPRel32 fixup with data and resize data area
378 void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
379 MCDataFragment *DF = getOrCreateDataFragment();
381 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
383 DF->getContents().resize(DF->getContents().size() + 8, 0);
386 void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
387 // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
388 // problems evaluating expressions across multiple fragments.
389 getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
392 void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
393 unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
394 insert(new MCFillFragment(0, ItemSize, NumBytes));
397 void MCObjectStreamer::FinishImpl() {
398 // If we are generating dwarf for assembly source files dump out the sections.
399 if (getContext().getGenDwarfForAssembly())
400 MCGenDwarfInfo::Emit(this);
402 // Dump out the dwarf file & directory tables and line tables.
403 MCDwarfLineTable::Emit(this);
405 getAssembler().Finish();