| //===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/MC/MCObjectStreamer.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/MC/MCAsmBackend.h" |
| #include "llvm/MC/MCAsmInfo.h" |
| #include "llvm/MC/MCAssembler.h" |
| #include "llvm/MC/MCCodeEmitter.h" |
| #include "llvm/MC/MCContext.h" |
| #include "llvm/MC/MCDwarf.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCObjectWriter.h" |
| #include "llvm/MC/MCSection.h" |
| #include "llvm/MC/MCSymbol.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/TargetRegistry.h" |
| using namespace llvm; |
| |
| MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB, |
| raw_pwrite_stream &OS, |
| MCCodeEmitter *Emitter_) |
| : MCStreamer(Context), |
| Assembler(new MCAssembler(Context, TAB, *Emitter_, |
| *TAB.createObjectWriter(OS), OS)), |
| EmitEHFrame(true), EmitDebugFrame(false) {} |
| |
| MCObjectStreamer::~MCObjectStreamer() { |
| delete &Assembler->getBackend(); |
| delete &Assembler->getEmitter(); |
| delete &Assembler->getWriter(); |
| delete Assembler; |
| } |
| |
| void MCObjectStreamer::flushPendingLabels(MCFragment *F, uint64_t FOffset) { |
| if (PendingLabels.size()) { |
| if (!F) { |
| F = new MCDataFragment(); |
| MCSection *CurSection = getCurrentSectionOnly(); |
| CurSection->getFragmentList().insert(CurInsertionPoint, F); |
| F->setParent(CurSection); |
| } |
| for (MCSymbol *Sym : PendingLabels) { |
| Sym->setFragment(F); |
| Sym->setOffset(FOffset); |
| } |
| PendingLabels.clear(); |
| } |
| } |
| |
| void MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi, |
| const MCSymbol *Lo, |
| unsigned Size) { |
| // If not assigned to the same (valid) fragment, fallback. |
| if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment()) { |
| MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size); |
| return; |
| } |
| |
| assert(Hi->getOffset() >= Lo->getOffset() && |
| "Expected Hi to be greater than Lo"); |
| EmitIntValue(Hi->getOffset() - Lo->getOffset(), Size); |
| } |
| |
| void MCObjectStreamer::reset() { |
| if (Assembler) |
| Assembler->reset(); |
| CurInsertionPoint = MCSection::iterator(); |
| EmitEHFrame = true; |
| EmitDebugFrame = false; |
| PendingLabels.clear(); |
| MCStreamer::reset(); |
| } |
| |
| void MCObjectStreamer::EmitFrames(MCAsmBackend *MAB) { |
| if (!getNumFrameInfos()) |
| return; |
| |
| if (EmitEHFrame) |
| MCDwarfFrameEmitter::Emit(*this, MAB, true); |
| |
| if (EmitDebugFrame) |
| MCDwarfFrameEmitter::Emit(*this, MAB, false); |
| } |
| |
| MCFragment *MCObjectStreamer::getCurrentFragment() const { |
| assert(getCurrentSectionOnly() && "No current section!"); |
| |
| if (CurInsertionPoint != getCurrentSectionOnly()->getFragmentList().begin()) |
| return std::prev(CurInsertionPoint); |
| |
| return nullptr; |
| } |
| |
| MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() { |
| MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment()); |
| // When bundling is enabled, we don't want to add data to a fragment that |
| // already has instructions (see MCELFStreamer::EmitInstToData for details) |
| if (!F || (Assembler->isBundlingEnabled() && !Assembler->getRelaxAll() && |
| F->hasInstructions())) { |
| F = new MCDataFragment(); |
| insert(F); |
| } |
| return F; |
| } |
| |
| void MCObjectStreamer::visitUsedSymbol(const MCSymbol &Sym) { |
| Assembler->registerSymbol(Sym); |
| } |
| |
| void MCObjectStreamer::EmitCFISections(bool EH, bool Debug) { |
| MCStreamer::EmitCFISections(EH, Debug); |
| EmitEHFrame = EH; |
| EmitDebugFrame = Debug; |
| } |
| |
| void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size, |
| const SMLoc &Loc) { |
| MCStreamer::EmitValueImpl(Value, Size, Loc); |
| MCDataFragment *DF = getOrCreateDataFragment(); |
| flushPendingLabels(DF, DF->getContents().size()); |
| |
| MCLineEntry::Make(this, getCurrentSection().first); |
| |
| // Avoid fixups when possible. |
| int64_t AbsValue; |
| if (Value->evaluateAsAbsolute(AbsValue, getAssembler())) { |
| EmitIntValue(AbsValue, Size); |
| return; |
| } |
| DF->getFixups().push_back( |
| MCFixup::create(DF->getContents().size(), Value, |
| MCFixup::getKindForSize(Size, false), Loc)); |
| DF->getContents().resize(DF->getContents().size() + Size, 0); |
| } |
| |
| void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) { |
| // We need to create a local symbol to avoid relocations. |
| Frame.Begin = getContext().createTempSymbol(); |
| EmitLabel(Frame.Begin); |
| } |
| |
| void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) { |
| Frame.End = getContext().createTempSymbol(); |
| EmitLabel(Frame.End); |
| } |
| |
| void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) { |
| MCStreamer::EmitLabel(Symbol); |
| |
| getAssembler().registerSymbol(*Symbol); |
| assert(!Symbol->getFragment() && "Unexpected fragment on symbol data!"); |
| |
| // If there is a current fragment, mark the symbol as pointing into it. |
| // Otherwise queue the label and set its fragment pointer when we emit the |
| // next fragment. |
| auto *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment()); |
| if (F && !(getAssembler().isBundlingEnabled() && |
| getAssembler().getRelaxAll())) { |
| Symbol->setFragment(F); |
| Symbol->setOffset(F->getContents().size()); |
| } else { |
| PendingLabels.push_back(Symbol); |
| } |
| } |
| |
| void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) { |
| int64_t IntValue; |
| if (Value->evaluateAsAbsolute(IntValue, getAssembler())) { |
| EmitULEB128IntValue(IntValue); |
| return; |
| } |
| insert(new MCLEBFragment(*Value, false)); |
| } |
| |
| void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) { |
| int64_t IntValue; |
| if (Value->evaluateAsAbsolute(IntValue, getAssembler())) { |
| EmitSLEB128IntValue(IntValue); |
| return; |
| } |
| insert(new MCLEBFragment(*Value, true)); |
| } |
| |
| void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias, |
| const MCSymbol *Symbol) { |
| report_fatal_error("This file format doesn't support weak aliases."); |
| } |
| |
| void MCObjectStreamer::ChangeSection(MCSection *Section, |
| const MCExpr *Subsection) { |
| changeSectionImpl(Section, Subsection); |
| } |
| |
| bool MCObjectStreamer::changeSectionImpl(MCSection *Section, |
| const MCExpr *Subsection) { |
| assert(Section && "Cannot switch to a null section!"); |
| flushPendingLabels(nullptr); |
| |
| bool Created = getAssembler().registerSection(*Section); |
| |
| int64_t IntSubsection = 0; |
| if (Subsection && |
| !Subsection->evaluateAsAbsolute(IntSubsection, getAssembler())) |
| report_fatal_error("Cannot evaluate subsection number"); |
| if (IntSubsection < 0 || IntSubsection > 8192) |
| report_fatal_error("Subsection number out of range"); |
| CurInsertionPoint = |
| Section->getSubsectionInsertionPoint(unsigned(IntSubsection)); |
| return Created; |
| } |
| |
| void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) { |
| getAssembler().registerSymbol(*Symbol); |
| MCStreamer::EmitAssignment(Symbol, Value); |
| } |
| |
| bool MCObjectStreamer::mayHaveInstructions(MCSection &Sec) const { |
| return Sec.hasInstructions(); |
| } |
| |
| void MCObjectStreamer::EmitInstruction(const MCInst &Inst, |
| const MCSubtargetInfo &STI) { |
| MCStreamer::EmitInstruction(Inst, STI); |
| |
| MCSection *Sec = getCurrentSectionOnly(); |
| Sec->setHasInstructions(true); |
| |
| // Now that a machine instruction has been assembled into this section, make |
| // a line entry for any .loc directive that has been seen. |
| MCLineEntry::Make(this, getCurrentSection().first); |
| |
| // If this instruction doesn't need relaxation, just emit it as data. |
| MCAssembler &Assembler = getAssembler(); |
| if (!Assembler.getBackend().mayNeedRelaxation(Inst)) { |
| EmitInstToData(Inst, STI); |
| return; |
| } |
| |
| // Otherwise, relax and emit it as data if either: |
| // - The RelaxAll flag was passed |
| // - Bundling is enabled and this instruction is inside a bundle-locked |
| // group. We want to emit all such instructions into the same data |
| // fragment. |
| if (Assembler.getRelaxAll() || |
| (Assembler.isBundlingEnabled() && Sec->isBundleLocked())) { |
| MCInst Relaxed; |
| getAssembler().getBackend().relaxInstruction(Inst, Relaxed); |
| while (getAssembler().getBackend().mayNeedRelaxation(Relaxed)) |
| getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed); |
| EmitInstToData(Relaxed, STI); |
| return; |
| } |
| |
| // Otherwise emit to a separate fragment. |
| EmitInstToFragment(Inst, STI); |
| } |
| |
| void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst, |
| const MCSubtargetInfo &STI) { |
| if (getAssembler().getRelaxAll() && getAssembler().isBundlingEnabled()) |
| llvm_unreachable("All instructions should have already been relaxed"); |
| |
| // Always create a new, separate fragment here, because its size can change |
| // during relaxation. |
| MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI); |
| insert(IF); |
| |
| SmallString<128> Code; |
| raw_svector_ostream VecOS(Code); |
| getAssembler().getEmitter().encodeInstruction(Inst, VecOS, IF->getFixups(), |
| STI); |
| VecOS.flush(); |
| IF->getContents().append(Code.begin(), Code.end()); |
| } |
| |
| #ifndef NDEBUG |
| static const char *const BundlingNotImplementedMsg = |
| "Aligned bundling is not implemented for this object format"; |
| #endif |
| |
| void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) { |
| llvm_unreachable(BundlingNotImplementedMsg); |
| } |
| |
| void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) { |
| llvm_unreachable(BundlingNotImplementedMsg); |
| } |
| |
| void MCObjectStreamer::EmitBundleUnlock() { |
| llvm_unreachable(BundlingNotImplementedMsg); |
| } |
| |
| void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line, |
| unsigned Column, unsigned Flags, |
| unsigned Isa, |
| unsigned Discriminator, |
| StringRef FileName) { |
| // In case we see two .loc directives in a row, make sure the |
| // first one gets a line entry. |
| MCLineEntry::Make(this, getCurrentSection().first); |
| |
| this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags, |
| Isa, Discriminator, FileName); |
| } |
| |
| static const MCExpr *buildSymbolDiff(MCObjectStreamer &OS, const MCSymbol *A, |
| const MCSymbol *B) { |
| MCContext &Context = OS.getContext(); |
| MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None; |
| const MCExpr *ARef = MCSymbolRefExpr::create(A, Variant, Context); |
| const MCExpr *BRef = MCSymbolRefExpr::create(B, Variant, Context); |
| const MCExpr *AddrDelta = |
| MCBinaryExpr::create(MCBinaryExpr::Sub, ARef, BRef, Context); |
| return AddrDelta; |
| } |
| |
| static void emitDwarfSetLineAddr(MCObjectStreamer &OS, int64_t LineDelta, |
| const MCSymbol *Label, int PointerSize) { |
| // emit the sequence to set the address |
| OS.EmitIntValue(dwarf::DW_LNS_extended_op, 1); |
| OS.EmitULEB128IntValue(PointerSize + 1); |
| OS.EmitIntValue(dwarf::DW_LNE_set_address, 1); |
| OS.EmitSymbolValue(Label, PointerSize); |
| |
| // emit the sequence for the LineDelta (from 1) and a zero address delta. |
| MCDwarfLineAddr::Emit(&OS, LineDelta, 0); |
| } |
| |
| void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta, |
| const MCSymbol *LastLabel, |
| const MCSymbol *Label, |
| unsigned PointerSize) { |
| if (!LastLabel) { |
| emitDwarfSetLineAddr(*this, LineDelta, Label, PointerSize); |
| return; |
| } |
| const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel); |
| int64_t Res; |
| if (AddrDelta->evaluateAsAbsolute(Res, getAssembler())) { |
| MCDwarfLineAddr::Emit(this, LineDelta, Res); |
| return; |
| } |
| insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta)); |
| } |
| |
| void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel, |
| const MCSymbol *Label) { |
| const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel); |
| int64_t Res; |
| if (AddrDelta->evaluateAsAbsolute(Res, getAssembler())) { |
| MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res); |
| return; |
| } |
| insert(new MCDwarfCallFrameFragment(*AddrDelta)); |
| } |
| |
| void MCObjectStreamer::EmitBytes(StringRef Data) { |
| MCLineEntry::Make(this, getCurrentSection().first); |
| MCDataFragment *DF = getOrCreateDataFragment(); |
| flushPendingLabels(DF, DF->getContents().size()); |
| DF->getContents().append(Data.begin(), Data.end()); |
| } |
| |
| void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment, |
| int64_t Value, |
| unsigned ValueSize, |
| unsigned MaxBytesToEmit) { |
| if (MaxBytesToEmit == 0) |
| MaxBytesToEmit = ByteAlignment; |
| insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit)); |
| |
| // Update the maximum alignment on the current section if necessary. |
| MCSection *CurSec = getCurrentSection().first; |
| if (ByteAlignment > CurSec->getAlignment()) |
| CurSec->setAlignment(ByteAlignment); |
| } |
| |
| void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment, |
| unsigned MaxBytesToEmit) { |
| EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit); |
| cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true); |
| } |
| |
| bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset, |
| unsigned char Value) { |
| int64_t Res; |
| if (Offset->evaluateAsAbsolute(Res, getAssembler())) { |
| insert(new MCOrgFragment(*Offset, Value)); |
| return false; |
| } |
| |
| MCSymbol *CurrentPos = getContext().createTempSymbol(); |
| EmitLabel(CurrentPos); |
| MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None; |
| const MCExpr *Ref = |
| MCSymbolRefExpr::create(CurrentPos, Variant, getContext()); |
| const MCExpr *Delta = |
| MCBinaryExpr::create(MCBinaryExpr::Sub, Offset, Ref, getContext()); |
| |
| if (!Delta->evaluateAsAbsolute(Res, getAssembler())) |
| return true; |
| EmitFill(Res, Value); |
| return false; |
| } |
| |
| // Associate GPRel32 fixup with data and resize data area |
| void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) { |
| MCDataFragment *DF = getOrCreateDataFragment(); |
| flushPendingLabels(DF, DF->getContents().size()); |
| |
| DF->getFixups().push_back(MCFixup::create(DF->getContents().size(), |
| Value, FK_GPRel_4)); |
| DF->getContents().resize(DF->getContents().size() + 4, 0); |
| } |
| |
| // Associate GPRel32 fixup with data and resize data area |
| void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) { |
| MCDataFragment *DF = getOrCreateDataFragment(); |
| flushPendingLabels(DF, DF->getContents().size()); |
| |
| DF->getFixups().push_back(MCFixup::create(DF->getContents().size(), |
| Value, FK_GPRel_4)); |
| DF->getContents().resize(DF->getContents().size() + 8, 0); |
| } |
| |
| void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) { |
| // FIXME: A MCFillFragment would be more memory efficient but MCExpr has |
| // problems evaluating expressions across multiple fragments. |
| MCDataFragment *DF = getOrCreateDataFragment(); |
| flushPendingLabels(DF, DF->getContents().size()); |
| DF->getContents().append(NumBytes, FillValue); |
| } |
| |
| void MCObjectStreamer::EmitZeros(uint64_t NumBytes) { |
| const MCSection *Sec = getCurrentSection().first; |
| assert(Sec && "need a section"); |
| unsigned ItemSize = Sec->isVirtualSection() ? 0 : 1; |
| insert(new MCFillFragment(0, ItemSize, NumBytes)); |
| } |
| |
| void MCObjectStreamer::FinishImpl() { |
| // If we are generating dwarf for assembly source files dump out the sections. |
| if (getContext().getGenDwarfForAssembly()) |
| MCGenDwarfInfo::Emit(this); |
| |
| // Dump out the dwarf file & directory tables and line tables. |
| MCDwarfLineTable::Emit(this); |
| |
| flushPendingLabels(nullptr); |
| getAssembler().Finish(); |
| } |