//===- 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/MCAssembler.h" #include "llvm/MC/MCCodeEmitter.h" #include "llvm/MC/MCCodeView.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/SourceMgr.h" using namespace llvm; MCObjectStreamer::MCObjectStreamer(MCContext &Context, std::unique_ptr TAB, raw_pwrite_stream &OS, std::unique_ptr Emitter) : MCStreamer(Context), ObjectWriter(TAB->createObjectWriter(OS)), TAB(std::move(TAB)), Emitter(std::move(Emitter)), Assembler(llvm::make_unique(Context, *this->TAB, *this->Emitter, *ObjectWriter)), EmitEHFrame(true), EmitDebugFrame(false) {} MCObjectStreamer::~MCObjectStreamer() {} void MCObjectStreamer::flushPendingLabels(MCFragment *F, uint64_t FOffset) { if (PendingLabels.empty()) return; 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() || Hi->isVariable() || Lo->isVariable()) { MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size); return; } 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(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; } MCPaddingFragment *MCObjectStreamer::getOrCreatePaddingFragment() { MCPaddingFragment *F = dyn_cast_or_null(getCurrentFragment()); if (!F) { F = new MCPaddingFragment(); 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, SMLoc Loc) { MCStreamer::EmitValueImpl(Value, Size, Loc); MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); MCCVLineEntry::Make(this); MCDwarfLineEntry::Make(this, getCurrentSectionOnly()); // Avoid fixups when possible. int64_t AbsValue; if (Value->evaluateAsAbsolute(AbsValue, getAssembler())) { if (!isUIntN(8 * Size, AbsValue) && !isIntN(8 * Size, AbsValue)) { getContext().reportError( Loc, "value evaluated as " + Twine(AbsValue) + " is out of range."); return; } 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); } MCSymbol *MCObjectStreamer::EmitCFILabel() { MCSymbol *Label = getContext().createTempSymbol("cfi", true); EmitLabel(Label); return Label; } 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, SMLoc Loc) { MCStreamer::EmitLabel(Symbol, Loc); getAssembler().registerSymbol(*Symbol); // 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(getCurrentFragment()); if (F && !(getAssembler().isBundlingEnabled() && getAssembler().getRelaxAll())) { Symbol->setFragment(F); Symbol->setOffset(F->getContents().size()); } else { PendingLabels.push_back(Symbol); } } void MCObjectStreamer::EmitLabel(MCSymbol *Symbol, SMLoc Loc, MCFragment *F) { MCStreamer::EmitLabel(Symbol, Loc); getAssembler().registerSymbol(*Symbol); auto *DF = dyn_cast_or_null(F); if (DF) Symbol->setFragment(F); 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); getContext().clearDwarfLocSeen(); 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, bool) { getAssembler().getBackend().handleCodePaddingInstructionBegin(Inst); EmitInstructionImpl(Inst, STI); getAssembler().getBackend().handleCodePaddingInstructionEnd(Inst); } void MCObjectStreamer::EmitInstructionImpl(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. MCCVLineEntry::Make(this); MCDwarfLineEntry::Make(this, getCurrentSectionOnly()); // 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, STI, Relaxed); while (getAssembler().getBackend().mayNeedRelaxation(Relaxed)) getAssembler().getBackend().relaxInstruction(Relaxed, STI, 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); 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. MCDwarfLineEntry::Make(this, getCurrentSectionOnly()); 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, MCDwarfLineTableParams Params, 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, Params, LineDelta, 0); } void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta, const MCSymbol *LastLabel, const MCSymbol *Label, unsigned PointerSize) { if (!LastLabel) { emitDwarfSetLineAddr(*this, Assembler->getDWARFLinetableParams(), LineDelta, Label, PointerSize); return; } const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel); int64_t Res; if (AddrDelta->evaluateAsAbsolute(Res, getAssembler())) { MCDwarfLineAddr::Emit(this, Assembler->getDWARFLinetableParams(), 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::EmitCVLocDirective(unsigned FunctionId, unsigned FileNo, unsigned Line, unsigned Column, bool PrologueEnd, bool IsStmt, StringRef FileName, SMLoc Loc) { // In case we see two .cv_loc directives in a row, make sure the // first one gets a line entry. MCCVLineEntry::Make(this); this->MCStreamer::EmitCVLocDirective(FunctionId, FileNo, Line, Column, PrologueEnd, IsStmt, FileName, Loc); } void MCObjectStreamer::EmitCVLinetableDirective(unsigned FunctionId, const MCSymbol *Begin, const MCSymbol *End) { getContext().getCVContext().emitLineTableForFunction(*this, FunctionId, Begin, End); this->MCStreamer::EmitCVLinetableDirective(FunctionId, Begin, End); } void MCObjectStreamer::EmitCVInlineLinetableDirective( unsigned PrimaryFunctionId, unsigned SourceFileId, unsigned SourceLineNum, const MCSymbol *FnStartSym, const MCSymbol *FnEndSym) { getContext().getCVContext().emitInlineLineTableForFunction( *this, PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym, FnEndSym); this->MCStreamer::EmitCVInlineLinetableDirective( PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym, FnEndSym); } void MCObjectStreamer::EmitCVDefRangeDirective( ArrayRef> Ranges, StringRef FixedSizePortion) { getContext().getCVContext().emitDefRange(*this, Ranges, FixedSizePortion); this->MCStreamer::EmitCVDefRangeDirective(Ranges, FixedSizePortion); } void MCObjectStreamer::EmitCVStringTableDirective() { getContext().getCVContext().emitStringTable(*this); } void MCObjectStreamer::EmitCVFileChecksumsDirective() { getContext().getCVContext().emitFileChecksums(*this); } void MCObjectStreamer::EmitCVFileChecksumOffsetDirective(unsigned FileNo) { getContext().getCVContext().emitFileChecksumOffset(*this, FileNo); } void MCObjectStreamer::EmitBytes(StringRef Data) { MCCVLineEntry::Make(this); MCDwarfLineEntry::Make(this, getCurrentSectionOnly()); 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 = getCurrentSectionOnly(); if (ByteAlignment > CurSec->getAlignment()) CurSec->setAlignment(ByteAlignment); } void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment, unsigned MaxBytesToEmit) { EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit); cast(getCurrentFragment())->setEmitNops(true); } void MCObjectStreamer::emitValueToOffset(const MCExpr *Offset, unsigned char Value, SMLoc Loc) { insert(new MCOrgFragment(*Offset, Value, Loc)); } void MCObjectStreamer::EmitCodePaddingBasicBlockStart( const MCCodePaddingContext &Context) { getAssembler().getBackend().handleCodePaddingBasicBlockStart(this, Context); } void MCObjectStreamer::EmitCodePaddingBasicBlockEnd( const MCCodePaddingContext &Context) { getAssembler().getBackend().handleCodePaddingBasicBlockEnd(Context); } // Associate DTPRel32 fixup with data and resize data area void MCObjectStreamer::EmitDTPRel32Value(const MCExpr *Value) { MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); DF->getFixups().push_back(MCFixup::create(DF->getContents().size(), Value, FK_DTPRel_4)); DF->getContents().resize(DF->getContents().size() + 4, 0); } // Associate DTPRel64 fixup with data and resize data area void MCObjectStreamer::EmitDTPRel64Value(const MCExpr *Value) { MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); DF->getFixups().push_back(MCFixup::create(DF->getContents().size(), Value, FK_DTPRel_8)); DF->getContents().resize(DF->getContents().size() + 8, 0); } // Associate TPRel32 fixup with data and resize data area void MCObjectStreamer::EmitTPRel32Value(const MCExpr *Value) { MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); DF->getFixups().push_back(MCFixup::create(DF->getContents().size(), Value, FK_TPRel_4)); DF->getContents().resize(DF->getContents().size() + 4, 0); } // Associate TPRel64 fixup with data and resize data area void MCObjectStreamer::EmitTPRel64Value(const MCExpr *Value) { MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); DF->getFixups().push_back(MCFixup::create(DF->getContents().size(), Value, FK_TPRel_8)); DF->getContents().resize(DF->getContents().size() + 8, 0); } // 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 GPRel64 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); } bool MCObjectStreamer::EmitRelocDirective(const MCExpr &Offset, StringRef Name, const MCExpr *Expr, SMLoc Loc) { int64_t OffsetValue; if (!Offset.evaluateAsAbsolute(OffsetValue)) llvm_unreachable("Offset is not absolute"); if (OffsetValue < 0) llvm_unreachable("Offset is negative"); MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); Optional MaybeKind = Assembler->getBackend().getFixupKind(Name); if (!MaybeKind.hasValue()) return true; MCFixupKind Kind = *MaybeKind; if (Expr == nullptr) Expr = MCSymbolRefExpr::create(getContext().createTempSymbol(), getContext()); DF->getFixups().push_back(MCFixup::create(OffsetValue, Expr, Kind, Loc)); return false; } void MCObjectStreamer::emitFill(const MCExpr &NumBytes, uint64_t FillValue, SMLoc Loc) { MCDataFragment *DF = getOrCreateDataFragment(); flushPendingLabels(DF, DF->getContents().size()); assert(getCurrentSectionOnly() && "need a section"); insert(new MCFillFragment(FillValue, NumBytes, Loc)); } void MCObjectStreamer::emitFill(const MCExpr &NumValues, int64_t Size, int64_t Expr, SMLoc Loc) { int64_t IntNumValues; if (!NumValues.evaluateAsAbsolute(IntNumValues, getAssembler())) { getContext().reportError(Loc, "expected absolute expression"); return; } if (IntNumValues < 0) { getContext().getSourceManager()->PrintMessage( Loc, SourceMgr::DK_Warning, "'.fill' directive with negative repeat count has no effect"); return; } MCStreamer::emitFill(IntNumValues, Size, Expr); } void MCObjectStreamer::EmitFileDirective(StringRef Filename) { getAssembler().addFileName(Filename); } 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, getAssembler().getDWARFLinetableParams()); flushPendingLabels(nullptr); getAssembler().Finish(); }