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)),
32 MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
33 raw_ostream &OS, MCCodeEmitter *Emitter_,
34 MCAssembler *_Assembler)
35 : MCStreamer(Context), Assembler(_Assembler), CurSectionData(0) {}
37 MCObjectStreamer::~MCObjectStreamer() {
38 delete &Assembler->getBackend();
39 delete &Assembler->getEmitter();
40 delete &Assembler->getWriter();
44 void MCObjectStreamer::reset() {
48 CurInsertionPoint = MCSectionData::iterator();
52 MCFragment *MCObjectStreamer::getCurrentFragment() const {
53 assert(getCurrentSectionData() && "No current section!");
55 if (CurInsertionPoint != getCurrentSectionData()->getFragmentList().begin())
56 return std::prev(CurInsertionPoint);
61 MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
62 MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
63 // When bundling is enabled, we don't want to add data to a fragment that
64 // already has instructions (see MCELFStreamer::EmitInstToData for details)
65 if (!F || (Assembler->isBundlingEnabled() && F->hasInstructions())) {
66 F = new MCDataFragment();
72 const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
73 switch (Value->getKind()) {
75 cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
78 case MCExpr::Constant:
81 case MCExpr::Binary: {
82 const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
83 AddValueSymbols(BE->getLHS());
84 AddValueSymbols(BE->getRHS());
88 case MCExpr::SymbolRef:
89 Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
93 AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
100 void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size) {
101 MCDataFragment *DF = getOrCreateDataFragment();
103 MCLineEntry::Make(this, getCurrentSection().first);
105 // Avoid fixups when possible.
107 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
108 EmitIntValue(AbsValue, Size);
111 DF->getFixups().push_back(
112 MCFixup::Create(DF->getContents().size(), Value,
113 MCFixup::getKindForSize(Size, false)));
114 DF->getContents().resize(DF->getContents().size() + Size, 0);
117 void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
118 RecordProcStart(Frame);
121 void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
122 RecordProcEnd(Frame);
125 void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
126 MCStreamer::EmitLabel(Symbol);
128 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
130 // FIXME: This is wasteful, we don't necessarily need to create a data
131 // fragment. Instead, we should mark the symbol as pointing into the data
132 // fragment if it exists, otherwise we should just queue the label and set its
133 // fragment pointer when we emit the next fragment.
134 MCDataFragment *F = getOrCreateDataFragment();
135 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
137 SD.setOffset(F->getContents().size());
140 void MCObjectStreamer::EmitDebugLabel(MCSymbol *Symbol) {
144 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
146 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
147 EmitULEB128IntValue(IntValue);
150 Value = ForceExpAbs(Value);
151 insert(new MCLEBFragment(*Value, false));
154 void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
156 if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
157 EmitSLEB128IntValue(IntValue);
160 Value = ForceExpAbs(Value);
161 insert(new MCLEBFragment(*Value, true));
164 void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
165 const MCSymbol *Symbol) {
166 report_fatal_error("This file format doesn't support weak aliases.");
169 void MCObjectStreamer::ChangeSection(const MCSection *Section,
170 const MCExpr *Subsection) {
171 assert(Section && "Cannot switch to a null section!");
173 CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
175 int64_t IntSubsection = 0;
177 !Subsection->EvaluateAsAbsolute(IntSubsection, getAssembler()))
178 report_fatal_error("Cannot evaluate subsection number");
179 if (IntSubsection < 0 || IntSubsection > 8192)
180 report_fatal_error("Subsection number out of range");
182 CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
185 void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
186 getAssembler().getOrCreateSymbolData(*Symbol);
187 Symbol->setVariableValue(AddValueSymbols(Value));
190 void MCObjectStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) {
192 for (unsigned i = Inst.getNumOperands(); i--; )
193 if (Inst.getOperand(i).isExpr())
194 AddValueSymbols(Inst.getOperand(i).getExpr());
196 MCSectionData *SD = getCurrentSectionData();
197 SD->setHasInstructions(true);
199 // Now that a machine instruction has been assembled into this section, make
200 // a line entry for any .loc directive that has been seen.
201 MCLineEntry::Make(this, getCurrentSection().first);
203 // If this instruction doesn't need relaxation, just emit it as data.
204 MCAssembler &Assembler = getAssembler();
205 if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
206 EmitInstToData(Inst, STI);
210 // Otherwise, relax and emit it as data if either:
211 // - The RelaxAll flag was passed
212 // - Bundling is enabled and this instruction is inside a bundle-locked
213 // group. We want to emit all such instructions into the same data
215 if (Assembler.getRelaxAll() ||
216 (Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
218 getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
219 while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
220 getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
221 EmitInstToData(Relaxed, STI);
225 // Otherwise emit to a separate fragment.
226 EmitInstToFragment(Inst, STI);
229 void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
230 const MCSubtargetInfo &STI) {
231 // Always create a new, separate fragment here, because its size can change
232 // during relaxation.
233 MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
236 SmallString<128> Code;
237 raw_svector_ostream VecOS(Code);
238 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups(),
241 IF->getContents().append(Code.begin(), Code.end());
245 static const char *const BundlingNotImplementedMsg =
246 "Aligned bundling is not implemented for this object format";
249 void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
250 llvm_unreachable(BundlingNotImplementedMsg);
253 void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
254 llvm_unreachable(BundlingNotImplementedMsg);
257 void MCObjectStreamer::EmitBundleUnlock() {
258 llvm_unreachable(BundlingNotImplementedMsg);
261 void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
262 unsigned Column, unsigned Flags,
264 unsigned Discriminator,
265 StringRef FileName) {
266 // In case we see two .loc directives in a row, make sure the
267 // first one gets a line entry.
268 MCLineEntry::Make(this, getCurrentSection().first);
270 this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
271 Isa, Discriminator, FileName);
274 void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
275 const MCSymbol *LastLabel,
276 const MCSymbol *Label,
277 unsigned PointerSize) {
279 EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
282 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
284 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
285 MCDwarfLineAddr::Emit(this, LineDelta, Res);
288 AddrDelta = ForceExpAbs(AddrDelta);
289 insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
292 void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
293 const MCSymbol *Label) {
294 const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
296 if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
297 MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
300 AddrDelta = ForceExpAbs(AddrDelta);
301 insert(new MCDwarfCallFrameFragment(*AddrDelta));
304 void MCObjectStreamer::EmitBytes(StringRef Data) {
305 MCLineEntry::Make(this, getCurrentSection().first);
306 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
309 void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
312 unsigned MaxBytesToEmit) {
313 if (MaxBytesToEmit == 0)
314 MaxBytesToEmit = ByteAlignment;
315 insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
317 // Update the maximum alignment on the current section if necessary.
318 if (ByteAlignment > getCurrentSectionData()->getAlignment())
319 getCurrentSectionData()->setAlignment(ByteAlignment);
322 void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
323 unsigned MaxBytesToEmit) {
324 EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
325 cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
328 bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
329 unsigned char Value) {
331 if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
332 insert(new MCOrgFragment(*Offset, Value));
336 MCSymbol *CurrentPos = getContext().CreateTempSymbol();
337 EmitLabel(CurrentPos);
338 MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
340 MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
341 const MCExpr *Delta =
342 MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
344 if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
346 EmitFill(Res, Value);
350 // Associate GPRel32 fixup with data and resize data area
351 void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
352 MCDataFragment *DF = getOrCreateDataFragment();
354 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
356 DF->getContents().resize(DF->getContents().size() + 4, 0);
359 // Associate GPRel32 fixup with data and resize data area
360 void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
361 MCDataFragment *DF = getOrCreateDataFragment();
363 DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
365 DF->getContents().resize(DF->getContents().size() + 8, 0);
368 void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
369 // FIXME: A MCFillFragment would be more memory efficient but MCExpr has
370 // problems evaluating expressions across multiple fragments.
371 getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
374 void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
375 unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
376 insert(new MCFillFragment(0, ItemSize, NumBytes));
379 void MCObjectStreamer::FinishImpl() {
380 // Dump out the dwarf file & directory tables and line tables.
381 const MCSymbol *LineSectionSymbol = NULL;
382 if (!getContext().getMCLineTableSymbols().empty() ||
383 getContext().hasDwarfFiles())
384 LineSectionSymbol = MCDwarfFileTable::Emit(this);
386 // If we are generating dwarf for assembly source files dump out the sections.
387 if (getContext().getGenDwarfForAssembly())
388 MCGenDwarfInfo::Emit(this, LineSectionSymbol);
390 getAssembler().Finish();