//===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "llvm/MC/MCDwarf.h" #include "llvm/ADT/Hashing.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/Twine.h" #include "llvm/Config/config.h" #include "llvm/MC/MCAsmInfo.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCObjectFileInfo.h" #include "llvm/MC/MCObjectStreamer.h" #include "llvm/MC/MCRegisterInfo.h" #include "llvm/MC/MCSection.h" #include "llvm/MC/MCSymbol.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/LEB128.h" #include "llvm/Support/Path.h" #include "llvm/Support/SourceMgr.h" #include "llvm/Support/raw_ostream.h" using namespace llvm; // Given a special op, return the address skip amount (in units of // DWARF2_LINE_MIN_INSN_LENGTH. #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE) // The maximum address skip amount that can be encoded with a special op. #define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255) // First special line opcode - leave room for the standard opcodes. // Note: If you want to change this, you'll have to update the // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit(). #define DWARF2_LINE_OPCODE_BASE 13 // Minimum line offset in a special line info. opcode. This value // was chosen to give a reasonable range of values. #define DWARF2_LINE_BASE -5 // Range of line offsets in a special line info. opcode. #define DWARF2_LINE_RANGE 14 static inline uint64_t ScaleAddrDelta(MCContext &Context, uint64_t AddrDelta) { unsigned MinInsnLength = Context.getAsmInfo()->getMinInstAlignment(); if (MinInsnLength == 1) return AddrDelta; if (AddrDelta % MinInsnLength != 0) { // TODO: report this error, but really only once. ; } return AddrDelta / MinInsnLength; } // // This is called when an instruction is assembled into the specified section // and if there is information from the last .loc directive that has yet to have // a line entry made for it is made. // void MCLineEntry::Make(MCObjectStreamer *MCOS, const MCSection *Section) { if (!MCOS->getContext().getDwarfLocSeen()) return; // Create a symbol at in the current section for use in the line entry. MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol(); // Set the value of the symbol to use for the MCLineEntry. MCOS->EmitLabel(LineSym); // Get the current .loc info saved in the context. const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc(); // Create a (local) line entry with the symbol and the current .loc info. MCLineEntry LineEntry(LineSym, DwarfLoc); // clear DwarfLocSeen saying the current .loc info is now used. MCOS->getContext().ClearDwarfLocSeen(); // Add the line entry to this section's entries. MCOS->getContext() .getMCDwarfLineTable(MCOS->getContext().getDwarfCompileUnitID()) .getMCLineSections() .addLineEntry(LineEntry, Section); } // // This helper routine returns an expression of End - Start + IntVal . // static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS, const MCSymbol &Start, const MCSymbol &End, int IntVal) { MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None; const MCExpr *Res = MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext()); const MCExpr *RHS = MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext()); const MCExpr *Res1 = MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext()); const MCExpr *Res2 = MCConstantExpr::Create(IntVal, MCOS.getContext()); const MCExpr *Res3 = MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext()); return Res3; } // // This emits the Dwarf line table for the specified section from the entries // in the LineSection. // static inline void EmitDwarfLineTable(MCObjectStreamer *MCOS, const MCSection *Section, const MCLineSection::MCLineEntryCollection &LineEntries) { unsigned FileNum = 1; unsigned LastLine = 1; unsigned Column = 0; unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0; unsigned Isa = 0; unsigned Discriminator = 0; MCSymbol *LastLabel = nullptr; // Loop through each MCLineEntry and encode the dwarf line number table. for (auto it = LineEntries.begin(), ie = LineEntries.end(); it != ie; ++it) { if (FileNum != it->getFileNum()) { FileNum = it->getFileNum(); MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1); MCOS->EmitULEB128IntValue(FileNum); } if (Column != it->getColumn()) { Column = it->getColumn(); MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1); MCOS->EmitULEB128IntValue(Column); } if (Discriminator != it->getDiscriminator()) { Discriminator = it->getDiscriminator(); unsigned Size = getULEB128Size(Discriminator); MCOS->EmitIntValue(dwarf::DW_LNS_extended_op, 1); MCOS->EmitULEB128IntValue(Size + 1); MCOS->EmitIntValue(dwarf::DW_LNE_set_discriminator, 1); MCOS->EmitULEB128IntValue(Discriminator); } if (Isa != it->getIsa()) { Isa = it->getIsa(); MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1); MCOS->EmitULEB128IntValue(Isa); } if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) { Flags = it->getFlags(); MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1); } if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK) MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1); if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END) MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1); if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN) MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1); int64_t LineDelta = static_cast(it->getLine()) - LastLine; MCSymbol *Label = it->getLabel(); // At this point we want to emit/create the sequence to encode the delta in // line numbers and the increment of the address from the previous Label // and the current Label. const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo(); MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label, asmInfo->getPointerSize()); LastLine = it->getLine(); LastLabel = Label; } // Emit a DW_LNE_end_sequence for the end of the section. // Using the pointer Section create a temporary label at the end of the // section and use that and the LastLabel to compute the address delta // and use INT64_MAX as the line delta which is the signal that this is // actually a DW_LNE_end_sequence. // Switch to the section to be able to create a symbol at its end. // TODO: keep track of the last subsection so that this symbol appears in the // correct place. MCOS->SwitchSection(Section); MCContext &context = MCOS->getContext(); // Create a symbol at the end of the section. MCSymbol *SectionEnd = context.CreateTempSymbol(); // Set the value of the symbol, as we are at the end of the section. MCOS->EmitLabel(SectionEnd); // Switch back the dwarf line section. MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection()); const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo(); MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd, asmInfo->getPointerSize()); } // // This emits the Dwarf file and the line tables. // void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS) { MCContext &context = MCOS->getContext(); auto &LineTables = context.getMCDwarfLineTables(); // Bail out early so we don't switch to the debug_line section needlessly and // in doing so create an unnecessary (if empty) section. if (LineTables.empty()) return; // Switch to the section where the table will be emitted into. MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection()); // Handle the rest of the Compile Units. for (const auto &CUIDTablePair : LineTables) CUIDTablePair.second.EmitCU(MCOS); } void MCDwarfDwoLineTable::Emit(MCStreamer &MCOS) const { MCOS.EmitLabel(Header.Emit(&MCOS, None).second); } std::pair MCDwarfLineTableHeader::Emit(MCStreamer *MCOS) const { static const char StandardOpcodeLengths[] = { 0, // length of DW_LNS_copy 1, // length of DW_LNS_advance_pc 1, // length of DW_LNS_advance_line 1, // length of DW_LNS_set_file 1, // length of DW_LNS_set_column 0, // length of DW_LNS_negate_stmt 0, // length of DW_LNS_set_basic_block 0, // length of DW_LNS_const_add_pc 1, // length of DW_LNS_fixed_advance_pc 0, // length of DW_LNS_set_prologue_end 0, // length of DW_LNS_set_epilogue_begin 1 // DW_LNS_set_isa }; assert(array_lengthof(StandardOpcodeLengths) == (DWARF2_LINE_OPCODE_BASE - 1)); return Emit(MCOS, StandardOpcodeLengths); } static const MCExpr *forceExpAbs(MCStreamer &OS, const MCExpr* Expr) { MCContext &Context = OS.getContext(); assert(!isa(Expr)); if (Context.getAsmInfo()->hasAggressiveSymbolFolding()) return Expr; MCSymbol *ABS = Context.CreateTempSymbol(); OS.EmitAssignment(ABS, Expr); return MCSymbolRefExpr::Create(ABS, Context); } static void emitAbsValue(MCStreamer &OS, const MCExpr *Value, unsigned Size) { const MCExpr *ABS = forceExpAbs(OS, Value); OS.EmitValue(ABS, Size); } std::pair MCDwarfLineTableHeader::Emit(MCStreamer *MCOS, ArrayRef StandardOpcodeLengths) const { MCContext &context = MCOS->getContext(); // Create a symbol at the beginning of the line table. MCSymbol *LineStartSym = Label; if (!LineStartSym) LineStartSym = context.CreateTempSymbol(); // Set the value of the symbol, as we are at the start of the line table. MCOS->EmitLabel(LineStartSym); // Create a symbol for the end of the section (to be set when we get there). MCSymbol *LineEndSym = context.CreateTempSymbol(); // The first 4 bytes is the total length of the information for this // compilation unit (not including these 4 bytes for the length). emitAbsValue(*MCOS, MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym, 4), 4); // Next 2 bytes is the Version, which is Dwarf 2. MCOS->EmitIntValue(2, 2); // Create a symbol for the end of the prologue (to be set when we get there). MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end // Length of the prologue, is the next 4 bytes. Which is the start of the // section to the end of the prologue. Not including the 4 bytes for the // total length, the 2 bytes for the version, and these 4 bytes for the // length of the prologue. emitAbsValue( *MCOS, MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym, (4 + 2 + 4)), 4); // Parameters of the state machine, are next. MCOS->EmitIntValue(context.getAsmInfo()->getMinInstAlignment(), 1); MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1); MCOS->EmitIntValue(DWARF2_LINE_BASE, 1); MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1); MCOS->EmitIntValue(StandardOpcodeLengths.size() + 1, 1); // Standard opcode lengths for (char Length : StandardOpcodeLengths) MCOS->EmitIntValue(Length, 1); // Put out the directory and file tables. // First the directory table. for (unsigned i = 0; i < MCDwarfDirs.size(); i++) { MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string } MCOS->EmitIntValue(0, 1); // Terminate the directory list // Second the file table. for (unsigned i = 1; i < MCDwarfFiles.size(); i++) { assert(!MCDwarfFiles[i].Name.empty()); MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string // the Directory num MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex); MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0) MCOS->EmitIntValue(0, 1); // filesize (always 0) } MCOS->EmitIntValue(0, 1); // Terminate the file list // This is the end of the prologue, so set the value of the symbol at the // end of the prologue (that was used in a previous expression). MCOS->EmitLabel(ProEndSym); return std::make_pair(LineStartSym, LineEndSym); } void MCDwarfLineTable::EmitCU(MCObjectStreamer *MCOS) const { MCSymbol *LineEndSym = Header.Emit(MCOS).second; // Put out the line tables. for (const auto &LineSec : MCLineSections.getMCLineEntries()) EmitDwarfLineTable(MCOS, LineSec.first, LineSec.second); if (MCOS->getContext().getAsmInfo()->getLinkerRequiresNonEmptyDwarfLines() && MCLineSections.getMCLineEntries().empty()) { // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures // it requires: // total_length >= prologue_length + 10 // We are 4 bytes short, since we have total_length = 51 and // prologue_length = 45 // The regular end_sequence should be sufficient. MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0); } // This is the end of the section, so set the value of the symbol at the end // of this section (that was used in a previous expression). MCOS->EmitLabel(LineEndSym); } unsigned MCDwarfLineTable::getFile(StringRef &Directory, StringRef &FileName, unsigned FileNumber) { return Header.getFile(Directory, FileName, FileNumber); } unsigned MCDwarfLineTableHeader::getFile(StringRef &Directory, StringRef &FileName, unsigned FileNumber) { if (Directory == CompilationDir) Directory = ""; if (FileName.empty()) { FileName = ""; Directory = ""; } assert(!FileName.empty()); if (FileNumber == 0) { FileNumber = SourceIdMap.size() + 1; assert((MCDwarfFiles.empty() || FileNumber == MCDwarfFiles.size()) && "Don't mix autonumbered and explicit numbered line table usage"); StringMapEntry &Ent = SourceIdMap.GetOrCreateValue( (Directory + Twine('\0') + FileName).str(), FileNumber); if (Ent.getValue() != FileNumber) return Ent.getValue(); } // Make space for this FileNumber in the MCDwarfFiles vector if needed. MCDwarfFiles.resize(FileNumber + 1); // Get the new MCDwarfFile slot for this FileNumber. MCDwarfFile &File = MCDwarfFiles[FileNumber]; // It is an error to use see the same number more than once. if (!File.Name.empty()) return 0; if (Directory.empty()) { // Separate the directory part from the basename of the FileName. StringRef tFileName = sys::path::filename(FileName); if (!tFileName.empty()) { Directory = sys::path::parent_path(FileName); if (!Directory.empty()) FileName = tFileName; } } // Find or make an entry in the MCDwarfDirs vector for this Directory. // Capture directory name. unsigned DirIndex; if (Directory.empty()) { // For FileNames with no directories a DirIndex of 0 is used. DirIndex = 0; } else { DirIndex = 0; for (unsigned End = MCDwarfDirs.size(); DirIndex < End; DirIndex++) { if (Directory == MCDwarfDirs[DirIndex]) break; } if (DirIndex >= MCDwarfDirs.size()) MCDwarfDirs.push_back(Directory); // The DirIndex is one based, as DirIndex of 0 is used for FileNames with // no directories. MCDwarfDirs[] is unlike MCDwarfFiles[] in that the // directory names are stored at MCDwarfDirs[DirIndex-1] where FileNames // are stored at MCDwarfFiles[FileNumber].Name . DirIndex++; } File.Name = FileName; File.DirIndex = DirIndex; // return the allocated FileNumber. return FileNumber; } /// Utility function to emit the encoding to a streamer. void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta, uint64_t AddrDelta) { MCContext &Context = MCOS->getContext(); SmallString<256> Tmp; raw_svector_ostream OS(Tmp); MCDwarfLineAddr::Encode(Context, LineDelta, AddrDelta, OS); MCOS->EmitBytes(OS.str()); } /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas. void MCDwarfLineAddr::Encode(MCContext &Context, int64_t LineDelta, uint64_t AddrDelta, raw_ostream &OS) { uint64_t Temp, Opcode; bool NeedCopy = false; // Scale the address delta by the minimum instruction length. AddrDelta = ScaleAddrDelta(Context, AddrDelta); // A LineDelta of INT64_MAX is a signal that this is actually a // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the // end_sequence to emit the matrix entry. if (LineDelta == INT64_MAX) { if (AddrDelta == MAX_SPECIAL_ADDR_DELTA) OS << char(dwarf::DW_LNS_const_add_pc); else { OS << char(dwarf::DW_LNS_advance_pc); encodeULEB128(AddrDelta, OS); } OS << char(dwarf::DW_LNS_extended_op); OS << char(1); OS << char(dwarf::DW_LNE_end_sequence); return; } // Bias the line delta by the base. Temp = LineDelta - DWARF2_LINE_BASE; // If the line increment is out of range of a special opcode, we must encode // it with DW_LNS_advance_line. if (Temp >= DWARF2_LINE_RANGE) { OS << char(dwarf::DW_LNS_advance_line); encodeSLEB128(LineDelta, OS); LineDelta = 0; Temp = 0 - DWARF2_LINE_BASE; NeedCopy = true; } // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode. if (LineDelta == 0 && AddrDelta == 0) { OS << char(dwarf::DW_LNS_copy); return; } // Bias the opcode by the special opcode base. Temp += DWARF2_LINE_OPCODE_BASE; // Avoid overflow when addr_delta is large. if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) { // Try using a special opcode. Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE; if (Opcode <= 255) { OS << char(Opcode); return; } // Try using DW_LNS_const_add_pc followed by special op. Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE; if (Opcode <= 255) { OS << char(dwarf::DW_LNS_const_add_pc); OS << char(Opcode); return; } } // Otherwise use DW_LNS_advance_pc. OS << char(dwarf::DW_LNS_advance_pc); encodeULEB128(AddrDelta, OS); if (NeedCopy) OS << char(dwarf::DW_LNS_copy); else OS << char(Temp); } // Utility function to write a tuple for .debug_abbrev. static void EmitAbbrev(MCStreamer *MCOS, uint64_t Name, uint64_t Form) { MCOS->EmitULEB128IntValue(Name); MCOS->EmitULEB128IntValue(Form); } // When generating dwarf for assembly source files this emits // the data for .debug_abbrev section which contains three DIEs. static void EmitGenDwarfAbbrev(MCStreamer *MCOS) { MCContext &context = MCOS->getContext(); MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); // DW_TAG_compile_unit DIE abbrev (1). MCOS->EmitULEB128IntValue(1); MCOS->EmitULEB128IntValue(dwarf::DW_TAG_compile_unit); MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1); EmitAbbrev(MCOS, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4); if (MCOS->getContext().getGenDwarfSectionSyms().size() > 1 && MCOS->getContext().getDwarfVersion() >= 3) { EmitAbbrev(MCOS, dwarf::DW_AT_ranges, dwarf::DW_FORM_data4); } else { EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); EmitAbbrev(MCOS, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr); } EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); if (!context.getCompilationDir().empty()) EmitAbbrev(MCOS, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string); StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); if (!DwarfDebugFlags.empty()) EmitAbbrev(MCOS, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string); EmitAbbrev(MCOS, dwarf::DW_AT_producer, dwarf::DW_FORM_string); EmitAbbrev(MCOS, dwarf::DW_AT_language, dwarf::DW_FORM_data2); EmitAbbrev(MCOS, 0, 0); // DW_TAG_label DIE abbrev (2). MCOS->EmitULEB128IntValue(2); MCOS->EmitULEB128IntValue(dwarf::DW_TAG_label); MCOS->EmitIntValue(dwarf::DW_CHILDREN_yes, 1); EmitAbbrev(MCOS, dwarf::DW_AT_name, dwarf::DW_FORM_string); EmitAbbrev(MCOS, dwarf::DW_AT_decl_file, dwarf::DW_FORM_data4); EmitAbbrev(MCOS, dwarf::DW_AT_decl_line, dwarf::DW_FORM_data4); EmitAbbrev(MCOS, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr); EmitAbbrev(MCOS, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag); EmitAbbrev(MCOS, 0, 0); // DW_TAG_unspecified_parameters DIE abbrev (3). MCOS->EmitULEB128IntValue(3); MCOS->EmitULEB128IntValue(dwarf::DW_TAG_unspecified_parameters); MCOS->EmitIntValue(dwarf::DW_CHILDREN_no, 1); EmitAbbrev(MCOS, 0, 0); // Terminate the abbreviations for this compilation unit. MCOS->EmitIntValue(0, 1); } // When generating dwarf for assembly source files this emits the data for // .debug_aranges section. This section contains a header and a table of pairs // of PointerSize'ed values for the address and size of section(s) with line // table entries. static void EmitGenDwarfAranges(MCStreamer *MCOS, const MCSymbol *InfoSectionSymbol) { MCContext &context = MCOS->getContext(); auto &Sections = context.getGenDwarfSectionSyms(); MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection()); // This will be the length of the .debug_aranges section, first account for // the size of each item in the header (see below where we emit these items). int Length = 4 + 2 + 4 + 1 + 1; // Figure the padding after the header before the table of address and size // pairs who's values are PointerSize'ed. const MCAsmInfo *asmInfo = context.getAsmInfo(); int AddrSize = asmInfo->getPointerSize(); int Pad = 2 * AddrSize - (Length & (2 * AddrSize - 1)); if (Pad == 2 * AddrSize) Pad = 0; Length += Pad; // Add the size of the pair of PointerSize'ed values for the address and size // of each section we have in the table. Length += 2 * AddrSize * Sections.size(); // And the pair of terminating zeros. Length += 2 * AddrSize; // Emit the header for this section. // The 4 byte length not including the 4 byte value for the length. MCOS->EmitIntValue(Length - 4, 4); // The 2 byte version, which is 2. MCOS->EmitIntValue(2, 2); // The 4 byte offset to the compile unit in the .debug_info from the start // of the .debug_info. if (InfoSectionSymbol) MCOS->EmitSymbolValue(InfoSectionSymbol, 4, asmInfo->needsDwarfSectionOffsetDirective()); else MCOS->EmitIntValue(0, 4); // The 1 byte size of an address. MCOS->EmitIntValue(AddrSize, 1); // The 1 byte size of a segment descriptor, we use a value of zero. MCOS->EmitIntValue(0, 1); // Align the header with the padding if needed, before we put out the table. for(int i = 0; i < Pad; i++) MCOS->EmitIntValue(0, 1); // Now emit the table of pairs of PointerSize'ed values for the section // addresses and sizes. for (const auto &sec : Sections) { MCSymbol *StartSymbol = sec.second.first; MCSymbol *EndSymbol = sec.second.second; assert(StartSymbol && "StartSymbol must not be NULL"); assert(EndSymbol && "EndSymbol must not be NULL"); const MCExpr *Addr = MCSymbolRefExpr::Create( StartSymbol, MCSymbolRefExpr::VK_None, context); const MCExpr *Size = MakeStartMinusEndExpr(*MCOS, *StartSymbol, *EndSymbol, 0); MCOS->EmitValue(Addr, AddrSize); emitAbsValue(*MCOS, Size, AddrSize); } // And finally the pair of terminating zeros. MCOS->EmitIntValue(0, AddrSize); MCOS->EmitIntValue(0, AddrSize); } // When generating dwarf for assembly source files this emits the data for // .debug_info section which contains three parts. The header, the compile_unit // DIE and a list of label DIEs. static void EmitGenDwarfInfo(MCStreamer *MCOS, const MCSymbol *AbbrevSectionSymbol, const MCSymbol *LineSectionSymbol, const MCSymbol *RangesSectionSymbol) { MCContext &context = MCOS->getContext(); MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection()); // Create a symbol at the start and end of this section used in here for the // expression to calculate the length in the header. MCSymbol *InfoStart = context.CreateTempSymbol(); MCOS->EmitLabel(InfoStart); MCSymbol *InfoEnd = context.CreateTempSymbol(); // First part: the header. // The 4 byte total length of the information for this compilation unit, not // including these 4 bytes. const MCExpr *Length = MakeStartMinusEndExpr(*MCOS, *InfoStart, *InfoEnd, 4); emitAbsValue(*MCOS, Length, 4); // The 2 byte DWARF version. MCOS->EmitIntValue(context.getDwarfVersion(), 2); const MCAsmInfo &AsmInfo = *context.getAsmInfo(); // The 4 byte offset to the debug abbrevs from the start of the .debug_abbrev, // it is at the start of that section so this is zero. if (AbbrevSectionSymbol == nullptr) MCOS->EmitIntValue(0, 4); else MCOS->EmitSymbolValue(AbbrevSectionSymbol, 4, AsmInfo.needsDwarfSectionOffsetDirective()); const MCAsmInfo *asmInfo = context.getAsmInfo(); int AddrSize = asmInfo->getPointerSize(); // The 1 byte size of an address. MCOS->EmitIntValue(AddrSize, 1); // Second part: the compile_unit DIE. // The DW_TAG_compile_unit DIE abbrev (1). MCOS->EmitULEB128IntValue(1); // DW_AT_stmt_list, a 4 byte offset from the start of the .debug_line section, // which is at the start of that section so this is zero. if (LineSectionSymbol) MCOS->EmitSymbolValue(LineSectionSymbol, 4, AsmInfo.needsDwarfSectionOffsetDirective()); else MCOS->EmitIntValue(0, 4); if (RangesSectionSymbol) { // There are multiple sections containing code, so we must use the // .debug_ranges sections. // AT_ranges, the 4 byte offset from the start of the .debug_ranges section // to the address range list for this compilation unit. MCOS->EmitSymbolValue(RangesSectionSymbol, 4); } else { // If we only have one non-empty code section, we can use the simpler // AT_low_pc and AT_high_pc attributes. // Find the first (and only) non-empty text section auto &Sections = context.getGenDwarfSectionSyms(); const auto TextSection = Sections.begin(); assert(TextSection != Sections.end() && "No text section found"); MCSymbol *StartSymbol = TextSection->second.first; MCSymbol *EndSymbol = TextSection->second.second; assert(StartSymbol && "StartSymbol must not be NULL"); assert(EndSymbol && "EndSymbol must not be NULL"); // AT_low_pc, the first address of the default .text section. const MCExpr *Start = MCSymbolRefExpr::Create( StartSymbol, MCSymbolRefExpr::VK_None, context); MCOS->EmitValue(Start, AddrSize); // AT_high_pc, the last address of the default .text section. const MCExpr *End = MCSymbolRefExpr::Create( EndSymbol, MCSymbolRefExpr::VK_None, context); MCOS->EmitValue(End, AddrSize); } // AT_name, the name of the source file. Reconstruct from the first directory // and file table entries. const SmallVectorImpl &MCDwarfDirs = context.getMCDwarfDirs(); if (MCDwarfDirs.size() > 0) { MCOS->EmitBytes(MCDwarfDirs[0]); MCOS->EmitBytes(sys::path::get_separator()); } const SmallVectorImpl &MCDwarfFiles = MCOS->getContext().getMCDwarfFiles(); MCOS->EmitBytes(MCDwarfFiles[1].Name); MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. // AT_comp_dir, the working directory the assembly was done in. if (!context.getCompilationDir().empty()) { MCOS->EmitBytes(context.getCompilationDir()); MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. } // AT_APPLE_flags, the command line arguments of the assembler tool. StringRef DwarfDebugFlags = context.getDwarfDebugFlags(); if (!DwarfDebugFlags.empty()){ MCOS->EmitBytes(DwarfDebugFlags); MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. } // AT_producer, the version of the assembler tool. StringRef DwarfDebugProducer = context.getDwarfDebugProducer(); if (!DwarfDebugProducer.empty()) MCOS->EmitBytes(DwarfDebugProducer); else MCOS->EmitBytes(StringRef("llvm-mc (based on LLVM " PACKAGE_VERSION ")")); MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. // AT_language, a 4 byte value. We use DW_LANG_Mips_Assembler as the dwarf2 // draft has no standard code for assembler. MCOS->EmitIntValue(dwarf::DW_LANG_Mips_Assembler, 2); // Third part: the list of label DIEs. // Loop on saved info for dwarf labels and create the DIEs for them. const std::vector &Entries = MCOS->getContext().getMCGenDwarfLabelEntries(); for (const auto &Entry : Entries) { // The DW_TAG_label DIE abbrev (2). MCOS->EmitULEB128IntValue(2); // AT_name, of the label without any leading underbar. MCOS->EmitBytes(Entry.getName()); MCOS->EmitIntValue(0, 1); // NULL byte to terminate the string. // AT_decl_file, index into the file table. MCOS->EmitIntValue(Entry.getFileNumber(), 4); // AT_decl_line, source line number. MCOS->EmitIntValue(Entry.getLineNumber(), 4); // AT_low_pc, start address of the label. const MCExpr *AT_low_pc = MCSymbolRefExpr::Create(Entry.getLabel(), MCSymbolRefExpr::VK_None, context); MCOS->EmitValue(AT_low_pc, AddrSize); // DW_AT_prototyped, a one byte flag value of 0 saying we have no prototype. MCOS->EmitIntValue(0, 1); // The DW_TAG_unspecified_parameters DIE abbrev (3). MCOS->EmitULEB128IntValue(3); // Add the NULL DIE terminating the DW_TAG_unspecified_parameters DIE's. MCOS->EmitIntValue(0, 1); } // Add the NULL DIE terminating the Compile Unit DIE's. MCOS->EmitIntValue(0, 1); // Now set the value of the symbol at the end of the info section. MCOS->EmitLabel(InfoEnd); } // When generating dwarf for assembly source files this emits the data for // .debug_ranges section. We only emit one range list, which spans all of the // executable sections of this file. static void EmitGenDwarfRanges(MCStreamer *MCOS) { MCContext &context = MCOS->getContext(); auto &Sections = context.getGenDwarfSectionSyms(); const MCAsmInfo *AsmInfo = context.getAsmInfo(); int AddrSize = AsmInfo->getPointerSize(); MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection()); for (const auto sec : Sections) { MCSymbol *StartSymbol = sec.second.first; MCSymbol *EndSymbol = sec.second.second; assert(StartSymbol && "StartSymbol must not be NULL"); assert(EndSymbol && "EndSymbol must not be NULL"); // Emit a base address selection entry for the start of this section const MCExpr *SectionStartAddr = MCSymbolRefExpr::Create( StartSymbol, MCSymbolRefExpr::VK_None, context); MCOS->EmitFill(AddrSize, 0xFF); MCOS->EmitValue(SectionStartAddr, AddrSize); // Emit a range list entry spanning this section const MCExpr *SectionSize = MakeStartMinusEndExpr(*MCOS, *StartSymbol, *EndSymbol, 0); MCOS->EmitIntValue(0, AddrSize); emitAbsValue(*MCOS, SectionSize, AddrSize); } // Emit end of list entry MCOS->EmitIntValue(0, AddrSize); MCOS->EmitIntValue(0, AddrSize); } // // When generating dwarf for assembly source files this emits the Dwarf // sections. // void MCGenDwarfInfo::Emit(MCStreamer *MCOS) { MCContext &context = MCOS->getContext(); // Create the dwarf sections in this order (.debug_line already created). const MCAsmInfo *AsmInfo = context.getAsmInfo(); bool CreateDwarfSectionSymbols = AsmInfo->doesDwarfUseRelocationsAcrossSections(); MCSymbol *LineSectionSymbol = nullptr; if (CreateDwarfSectionSymbols) LineSectionSymbol = MCOS->getDwarfLineTableSymbol(0); MCSymbol *AbbrevSectionSymbol = nullptr; MCSymbol *InfoSectionSymbol = nullptr; MCSymbol *RangesSectionSymbol = NULL; // Create end symbols for each section, and remove empty sections MCOS->getContext().finalizeDwarfSections(*MCOS); // If there are no sections to generate debug info for, we don't need // to do anything if (MCOS->getContext().getGenDwarfSectionSyms().empty()) return; // We only use the .debug_ranges section if we have multiple code sections, // and we are emitting a DWARF version which supports it. const bool UseRangesSection = MCOS->getContext().getGenDwarfSectionSyms().size() > 1 && MCOS->getContext().getDwarfVersion() >= 3; CreateDwarfSectionSymbols |= UseRangesSection; MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfInfoSection()); if (CreateDwarfSectionSymbols) { InfoSectionSymbol = context.CreateTempSymbol(); MCOS->EmitLabel(InfoSectionSymbol); } MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfAbbrevSection()); if (CreateDwarfSectionSymbols) { AbbrevSectionSymbol = context.CreateTempSymbol(); MCOS->EmitLabel(AbbrevSectionSymbol); } if (UseRangesSection) { MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection()); if (CreateDwarfSectionSymbols) { RangesSectionSymbol = context.CreateTempSymbol(); MCOS->EmitLabel(RangesSectionSymbol); } } assert((RangesSectionSymbol != NULL) || !UseRangesSection); MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfARangesSection()); // Output the data for .debug_aranges section. EmitGenDwarfAranges(MCOS, InfoSectionSymbol); if (UseRangesSection) EmitGenDwarfRanges(MCOS); // Output the data for .debug_abbrev section. EmitGenDwarfAbbrev(MCOS); // Output the data for .debug_info section. EmitGenDwarfInfo(MCOS, AbbrevSectionSymbol, LineSectionSymbol, RangesSectionSymbol); } // // When generating dwarf for assembly source files this is called when symbol // for a label is created. If this symbol is not a temporary and is in the // section that dwarf is being generated for, save the needed info to create // a dwarf label. // void MCGenDwarfLabelEntry::Make(MCSymbol *Symbol, MCStreamer *MCOS, SourceMgr &SrcMgr, SMLoc &Loc) { // We won't create dwarf labels for temporary symbols. if (Symbol->isTemporary()) return; MCContext &context = MCOS->getContext(); // We won't create dwarf labels for symbols in sections that we are not // generating debug info for. if (!context.getGenDwarfSectionSyms().count(MCOS->getCurrentSection().first)) return; // The dwarf label's name does not have the symbol name's leading // underbar if any. StringRef Name = Symbol->getName(); if (Name.startswith("_")) Name = Name.substr(1, Name.size()-1); // Get the dwarf file number to be used for the dwarf label. unsigned FileNumber = context.getGenDwarfFileNumber(); // Finding the line number is the expensive part which is why we just don't // pass it in as for some symbols we won't create a dwarf label. unsigned CurBuffer = SrcMgr.FindBufferContainingLoc(Loc); unsigned LineNumber = SrcMgr.FindLineNumber(Loc, CurBuffer); // We create a temporary symbol for use for the AT_high_pc and AT_low_pc // values so that they don't have things like an ARM thumb bit from the // original symbol. So when used they won't get a low bit set after // relocation. MCSymbol *Label = context.CreateTempSymbol(); MCOS->EmitLabel(Label); // Create and entry for the info and add it to the other entries. MCOS->getContext().addMCGenDwarfLabelEntry( MCGenDwarfLabelEntry(Name, FileNumber, LineNumber, Label)); } static int getDataAlignmentFactor(MCStreamer &streamer) { MCContext &context = streamer.getContext(); const MCAsmInfo *asmInfo = context.getAsmInfo(); int size = asmInfo->getCalleeSaveStackSlotSize(); if (asmInfo->isStackGrowthDirectionUp()) return size; else return -size; } static unsigned getSizeForEncoding(MCStreamer &streamer, unsigned symbolEncoding) { MCContext &context = streamer.getContext(); unsigned format = symbolEncoding & 0x0f; switch (format) { default: llvm_unreachable("Unknown Encoding"); case dwarf::DW_EH_PE_absptr: case dwarf::DW_EH_PE_signed: return context.getAsmInfo()->getPointerSize(); case dwarf::DW_EH_PE_udata2: case dwarf::DW_EH_PE_sdata2: return 2; case dwarf::DW_EH_PE_udata4: case dwarf::DW_EH_PE_sdata4: return 4; case dwarf::DW_EH_PE_udata8: case dwarf::DW_EH_PE_sdata8: return 8; } } static void emitFDESymbol(MCObjectStreamer &streamer, const MCSymbol &symbol, unsigned symbolEncoding, bool isEH) { MCContext &context = streamer.getContext(); const MCAsmInfo *asmInfo = context.getAsmInfo(); const MCExpr *v = asmInfo->getExprForFDESymbol(&symbol, symbolEncoding, streamer); unsigned size = getSizeForEncoding(streamer, symbolEncoding); if (asmInfo->doDwarfFDESymbolsUseAbsDiff() && isEH) emitAbsValue(streamer, v, size); else streamer.EmitValue(v, size); } static void EmitPersonality(MCStreamer &streamer, const MCSymbol &symbol, unsigned symbolEncoding) { MCContext &context = streamer.getContext(); const MCAsmInfo *asmInfo = context.getAsmInfo(); const MCExpr *v = asmInfo->getExprForPersonalitySymbol(&symbol, symbolEncoding, streamer); unsigned size = getSizeForEncoding(streamer, symbolEncoding); streamer.EmitValue(v, size); } namespace { class FrameEmitterImpl { int CFAOffset; bool IsEH; const MCSymbol *SectionStart; public: FrameEmitterImpl(bool isEH) : CFAOffset(0), IsEH(isEH), SectionStart(nullptr) {} void setSectionStart(const MCSymbol *Label) { SectionStart = Label; } /// Emit the unwind information in a compact way. void EmitCompactUnwind(MCObjectStreamer &streamer, const MCDwarfFrameInfo &frame); const MCSymbol &EmitCIE(MCObjectStreamer &streamer, const MCSymbol *personality, unsigned personalityEncoding, const MCSymbol *lsda, bool IsSignalFrame, unsigned lsdaEncoding, bool IsSimple); MCSymbol *EmitFDE(MCObjectStreamer &streamer, const MCSymbol &cieStart, const MCDwarfFrameInfo &frame); void EmitCFIInstructions(MCObjectStreamer &streamer, ArrayRef Instrs, MCSymbol *BaseLabel); void EmitCFIInstruction(MCObjectStreamer &Streamer, const MCCFIInstruction &Instr); }; } // end anonymous namespace static void emitEncodingByte(MCObjectStreamer &Streamer, unsigned Encoding) { Streamer.EmitIntValue(Encoding, 1); } void FrameEmitterImpl::EmitCFIInstruction(MCObjectStreamer &Streamer, const MCCFIInstruction &Instr) { int dataAlignmentFactor = getDataAlignmentFactor(Streamer); switch (Instr.getOperation()) { case MCCFIInstruction::OpRegister: { unsigned Reg1 = Instr.getRegister(); unsigned Reg2 = Instr.getRegister2(); Streamer.EmitIntValue(dwarf::DW_CFA_register, 1); Streamer.EmitULEB128IntValue(Reg1); Streamer.EmitULEB128IntValue(Reg2); return; } case MCCFIInstruction::OpWindowSave: { Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1); return; } case MCCFIInstruction::OpUndefined: { unsigned Reg = Instr.getRegister(); Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1); Streamer.EmitULEB128IntValue(Reg); return; } case MCCFIInstruction::OpAdjustCfaOffset: case MCCFIInstruction::OpDefCfaOffset: { const bool IsRelative = Instr.getOperation() == MCCFIInstruction::OpAdjustCfaOffset; Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1); if (IsRelative) CFAOffset += Instr.getOffset(); else CFAOffset = -Instr.getOffset(); Streamer.EmitULEB128IntValue(CFAOffset); return; } case MCCFIInstruction::OpDefCfa: { Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1); Streamer.EmitULEB128IntValue(Instr.getRegister()); CFAOffset = -Instr.getOffset(); Streamer.EmitULEB128IntValue(CFAOffset); return; } case MCCFIInstruction::OpDefCfaRegister: { Streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1); Streamer.EmitULEB128IntValue(Instr.getRegister()); return; } case MCCFIInstruction::OpOffset: case MCCFIInstruction::OpRelOffset: { const bool IsRelative = Instr.getOperation() == MCCFIInstruction::OpRelOffset; unsigned Reg = Instr.getRegister(); int Offset = Instr.getOffset(); if (IsRelative) Offset -= CFAOffset; Offset = Offset / dataAlignmentFactor; if (Offset < 0) { Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1); Streamer.EmitULEB128IntValue(Reg); Streamer.EmitSLEB128IntValue(Offset); } else if (Reg < 64) { Streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1); Streamer.EmitULEB128IntValue(Offset); } else { Streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1); Streamer.EmitULEB128IntValue(Reg); Streamer.EmitULEB128IntValue(Offset); } return; } case MCCFIInstruction::OpRememberState: Streamer.EmitIntValue(dwarf::DW_CFA_remember_state, 1); return; case MCCFIInstruction::OpRestoreState: Streamer.EmitIntValue(dwarf::DW_CFA_restore_state, 1); return; case MCCFIInstruction::OpSameValue: { unsigned Reg = Instr.getRegister(); Streamer.EmitIntValue(dwarf::DW_CFA_same_value, 1); Streamer.EmitULEB128IntValue(Reg); return; } case MCCFIInstruction::OpRestore: { unsigned Reg = Instr.getRegister(); Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1); return; } case MCCFIInstruction::OpEscape: Streamer.EmitBytes(Instr.getValues()); return; } llvm_unreachable("Unhandled case in switch"); } /// Emit frame instructions to describe the layout of the frame. void FrameEmitterImpl::EmitCFIInstructions(MCObjectStreamer &streamer, ArrayRef Instrs, MCSymbol *BaseLabel) { for (unsigned i = 0, N = Instrs.size(); i < N; ++i) { const MCCFIInstruction &Instr = Instrs[i]; MCSymbol *Label = Instr.getLabel(); // Throw out move if the label is invalid. if (Label && !Label->isDefined()) continue; // Not emitted, in dead code. // Advance row if new location. if (BaseLabel && Label) { MCSymbol *ThisSym = Label; if (ThisSym != BaseLabel) { streamer.EmitDwarfAdvanceFrameAddr(BaseLabel, ThisSym); BaseLabel = ThisSym; } } EmitCFIInstruction(streamer, Instr); } } /// Emit the unwind information in a compact way. void FrameEmitterImpl::EmitCompactUnwind(MCObjectStreamer &Streamer, const MCDwarfFrameInfo &Frame) { MCContext &Context = Streamer.getContext(); const MCObjectFileInfo *MOFI = Context.getObjectFileInfo(); // range-start range-length compact-unwind-enc personality-func lsda // _foo LfooEnd-_foo 0x00000023 0 0 // _bar LbarEnd-_bar 0x00000025 __gxx_personality except_tab1 // // .section __LD,__compact_unwind,regular,debug // // # compact unwind for _foo // .quad _foo // .set L1,LfooEnd-_foo // .long L1 // .long 0x01010001 // .quad 0 // .quad 0 // // # compact unwind for _bar // .quad _bar // .set L2,LbarEnd-_bar // .long L2 // .long 0x01020011 // .quad __gxx_personality // .quad except_tab1 uint32_t Encoding = Frame.CompactUnwindEncoding; if (!Encoding) return; bool DwarfEHFrameOnly = (Encoding == MOFI->getCompactUnwindDwarfEHFrameOnly()); // The encoding needs to know we have an LSDA. if (!DwarfEHFrameOnly && Frame.Lsda) Encoding |= 0x40000000; // Range Start unsigned FDEEncoding = MOFI->getFDEEncoding(); unsigned Size = getSizeForEncoding(Streamer, FDEEncoding); Streamer.EmitSymbolValue(Frame.Begin, Size); // Range Length const MCExpr *Range = MakeStartMinusEndExpr(Streamer, *Frame.Begin, *Frame.End, 0); emitAbsValue(Streamer, Range, 4); // Compact Encoding Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_udata4); Streamer.EmitIntValue(Encoding, Size); // Personality Function Size = getSizeForEncoding(Streamer, dwarf::DW_EH_PE_absptr); if (!DwarfEHFrameOnly && Frame.Personality) Streamer.EmitSymbolValue(Frame.Personality, Size); else Streamer.EmitIntValue(0, Size); // No personality fn // LSDA Size = getSizeForEncoding(Streamer, Frame.LsdaEncoding); if (!DwarfEHFrameOnly && Frame.Lsda) Streamer.EmitSymbolValue(Frame.Lsda, Size); else Streamer.EmitIntValue(0, Size); // No LSDA } const MCSymbol &FrameEmitterImpl::EmitCIE(MCObjectStreamer &streamer, const MCSymbol *personality, unsigned personalityEncoding, const MCSymbol *lsda, bool IsSignalFrame, unsigned lsdaEncoding, bool IsSimple) { MCContext &context = streamer.getContext(); const MCRegisterInfo *MRI = context.getRegisterInfo(); const MCObjectFileInfo *MOFI = context.getObjectFileInfo(); MCSymbol *sectionStart = context.CreateTempSymbol(); streamer.EmitLabel(sectionStart); MCSymbol *sectionEnd = context.CreateTempSymbol(); // Length const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart, *sectionEnd, 4); emitAbsValue(streamer, Length, 4); // CIE ID unsigned CIE_ID = IsEH ? 0 : -1; streamer.EmitIntValue(CIE_ID, 4); // Version // For DWARF2, we use CIE version 1 // For DWARF3+, we use CIE version 3 uint8_t CIEVersion = context.getDwarfVersion() <= 2 ? 1 : 3; streamer.EmitIntValue(CIEVersion, 1); // Augmentation String SmallString<8> Augmentation; if (IsEH) { Augmentation += "z"; if (personality) Augmentation += "P"; if (lsda) Augmentation += "L"; Augmentation += "R"; if (IsSignalFrame) Augmentation += "S"; streamer.EmitBytes(Augmentation.str()); } streamer.EmitIntValue(0, 1); // Code Alignment Factor streamer.EmitULEB128IntValue(context.getAsmInfo()->getMinInstAlignment()); // Data Alignment Factor streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer)); // Return Address Register if (CIEVersion == 1) { assert(MRI->getRARegister() <= 255 && "DWARF 2 encodes return_address_register in one byte"); streamer.EmitIntValue(MRI->getDwarfRegNum(MRI->getRARegister(), true), 1); } else { streamer.EmitULEB128IntValue( MRI->getDwarfRegNum(MRI->getRARegister(), true)); } // Augmentation Data Length (optional) unsigned augmentationLength = 0; if (IsEH) { if (personality) { // Personality Encoding augmentationLength += 1; // Personality augmentationLength += getSizeForEncoding(streamer, personalityEncoding); } if (lsda) augmentationLength += 1; // Encoding of the FDE pointers augmentationLength += 1; streamer.EmitULEB128IntValue(augmentationLength); // Augmentation Data (optional) if (personality) { // Personality Encoding emitEncodingByte(streamer, personalityEncoding); // Personality EmitPersonality(streamer, *personality, personalityEncoding); } if (lsda) emitEncodingByte(streamer, lsdaEncoding); // Encoding of the FDE pointers emitEncodingByte(streamer, MOFI->getFDEEncoding()); } // Initial Instructions const MCAsmInfo *MAI = context.getAsmInfo(); if (!IsSimple) { const std::vector &Instructions = MAI->getInitialFrameState(); EmitCFIInstructions(streamer, Instructions, nullptr); } // Padding streamer.EmitValueToAlignment(IsEH ? 4 : MAI->getPointerSize()); streamer.EmitLabel(sectionEnd); return *sectionStart; } MCSymbol *FrameEmitterImpl::EmitFDE(MCObjectStreamer &streamer, const MCSymbol &cieStart, const MCDwarfFrameInfo &frame) { MCContext &context = streamer.getContext(); MCSymbol *fdeStart = context.CreateTempSymbol(); MCSymbol *fdeEnd = context.CreateTempSymbol(); const MCObjectFileInfo *MOFI = context.getObjectFileInfo(); // Length const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0); emitAbsValue(streamer, Length, 4); streamer.EmitLabel(fdeStart); // CIE Pointer const MCAsmInfo *asmInfo = context.getAsmInfo(); if (IsEH) { const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart, 0); emitAbsValue(streamer, offset, 4); } else if (!asmInfo->doesDwarfUseRelocationsAcrossSections()) { const MCExpr *offset = MakeStartMinusEndExpr(streamer, *SectionStart, cieStart, 0); emitAbsValue(streamer, offset, 4); } else { streamer.EmitSymbolValue(&cieStart, 4); } // PC Begin unsigned PCEncoding = IsEH ? MOFI->getFDEEncoding() : (unsigned)dwarf::DW_EH_PE_absptr; unsigned PCSize = getSizeForEncoding(streamer, PCEncoding); emitFDESymbol(streamer, *frame.Begin, PCEncoding, IsEH); // PC Range const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin, *frame.End, 0); emitAbsValue(streamer, Range, PCSize); if (IsEH) { // Augmentation Data Length unsigned augmentationLength = 0; if (frame.Lsda) augmentationLength += getSizeForEncoding(streamer, frame.LsdaEncoding); streamer.EmitULEB128IntValue(augmentationLength); // Augmentation Data if (frame.Lsda) emitFDESymbol(streamer, *frame.Lsda, frame.LsdaEncoding, true); } // Call Frame Instructions EmitCFIInstructions(streamer, frame.Instructions, frame.Begin); // Padding streamer.EmitValueToAlignment(PCSize); return fdeEnd; } namespace { struct CIEKey { static const CIEKey getEmptyKey() { return CIEKey(nullptr, 0, -1, false, false); } static const CIEKey getTombstoneKey() { return CIEKey(nullptr, -1, 0, false, false); } CIEKey(const MCSymbol *Personality_, unsigned PersonalityEncoding_, unsigned LsdaEncoding_, bool IsSignalFrame_, bool IsSimple_) : Personality(Personality_), PersonalityEncoding(PersonalityEncoding_), LsdaEncoding(LsdaEncoding_), IsSignalFrame(IsSignalFrame_), IsSimple(IsSimple_) {} const MCSymbol *Personality; unsigned PersonalityEncoding; unsigned LsdaEncoding; bool IsSignalFrame; bool IsSimple; }; } namespace llvm { template <> struct DenseMapInfo { static CIEKey getEmptyKey() { return CIEKey::getEmptyKey(); } static CIEKey getTombstoneKey() { return CIEKey::getTombstoneKey(); } static unsigned getHashValue(const CIEKey &Key) { return static_cast(hash_combine(Key.Personality, Key.PersonalityEncoding, Key.LsdaEncoding, Key.IsSignalFrame, Key.IsSimple)); } static bool isEqual(const CIEKey &LHS, const CIEKey &RHS) { return LHS.Personality == RHS.Personality && LHS.PersonalityEncoding == RHS.PersonalityEncoding && LHS.LsdaEncoding == RHS.LsdaEncoding && LHS.IsSignalFrame == RHS.IsSignalFrame && LHS.IsSimple == RHS.IsSimple; } }; } void MCDwarfFrameEmitter::Emit(MCObjectStreamer &Streamer, MCAsmBackend *MAB, bool IsEH) { Streamer.generateCompactUnwindEncodings(MAB); MCContext &Context = Streamer.getContext(); const MCObjectFileInfo *MOFI = Context.getObjectFileInfo(); FrameEmitterImpl Emitter(IsEH); ArrayRef FrameArray = Streamer.getDwarfFrameInfos(); // Emit the compact unwind info if available. bool NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame(); if (IsEH && MOFI->getCompactUnwindSection()) { bool SectionEmitted = false; for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) { const MCDwarfFrameInfo &Frame = FrameArray[i]; if (Frame.CompactUnwindEncoding == 0) continue; if (!SectionEmitted) { Streamer.SwitchSection(MOFI->getCompactUnwindSection()); Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize()); SectionEmitted = true; } NeedsEHFrameSection |= Frame.CompactUnwindEncoding == MOFI->getCompactUnwindDwarfEHFrameOnly(); Emitter.EmitCompactUnwind(Streamer, Frame); } } if (!NeedsEHFrameSection) return; const MCSection &Section = IsEH ? *const_cast(MOFI)->getEHFrameSection() : *MOFI->getDwarfFrameSection(); Streamer.SwitchSection(&Section); MCSymbol *SectionStart = Context.CreateTempSymbol(); Streamer.EmitLabel(SectionStart); Emitter.setSectionStart(SectionStart); MCSymbol *FDEEnd = nullptr; DenseMap CIEStarts; const MCSymbol *DummyDebugKey = nullptr; NeedsEHFrameSection = !MOFI->getSupportsCompactUnwindWithoutEHFrame(); for (unsigned i = 0, n = FrameArray.size(); i < n; ++i) { const MCDwarfFrameInfo &Frame = FrameArray[i]; // Emit the label from the previous iteration if (FDEEnd) { Streamer.EmitLabel(FDEEnd); FDEEnd = nullptr; } if (!NeedsEHFrameSection && Frame.CompactUnwindEncoding != MOFI->getCompactUnwindDwarfEHFrameOnly()) // Don't generate an EH frame if we don't need one. I.e., it's taken care // of by the compact unwind encoding. continue; CIEKey Key(Frame.Personality, Frame.PersonalityEncoding, Frame.LsdaEncoding, Frame.IsSignalFrame, Frame.IsSimple); const MCSymbol *&CIEStart = IsEH ? CIEStarts[Key] : DummyDebugKey; if (!CIEStart) CIEStart = &Emitter.EmitCIE(Streamer, Frame.Personality, Frame.PersonalityEncoding, Frame.Lsda, Frame.IsSignalFrame, Frame.LsdaEncoding, Frame.IsSimple); FDEEnd = Emitter.EmitFDE(Streamer, *CIEStart, Frame); } Streamer.EmitValueToAlignment(Context.getAsmInfo()->getPointerSize()); if (FDEEnd) Streamer.EmitLabel(FDEEnd); } void MCDwarfFrameEmitter::EmitAdvanceLoc(MCObjectStreamer &Streamer, uint64_t AddrDelta) { MCContext &Context = Streamer.getContext(); SmallString<256> Tmp; raw_svector_ostream OS(Tmp); MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OS); Streamer.EmitBytes(OS.str()); } void MCDwarfFrameEmitter::EncodeAdvanceLoc(MCContext &Context, uint64_t AddrDelta, raw_ostream &OS) { // Scale the address delta by the minimum instruction length. AddrDelta = ScaleAddrDelta(Context, AddrDelta); if (AddrDelta == 0) { } else if (isUIntN(6, AddrDelta)) { uint8_t Opcode = dwarf::DW_CFA_advance_loc | AddrDelta; OS << Opcode; } else if (isUInt<8>(AddrDelta)) { OS << uint8_t(dwarf::DW_CFA_advance_loc1); OS << uint8_t(AddrDelta); } else if (isUInt<16>(AddrDelta)) { // FIXME: check what is the correct behavior on a big endian machine. OS << uint8_t(dwarf::DW_CFA_advance_loc2); OS << uint8_t( AddrDelta & 0xff); OS << uint8_t((AddrDelta >> 8) & 0xff); } else { // FIXME: check what is the correct behavior on a big endian machine. assert(isUInt<32>(AddrDelta)); OS << uint8_t(dwarf::DW_CFA_advance_loc4); OS << uint8_t( AddrDelta & 0xff); OS << uint8_t((AddrDelta >> 8) & 0xff); OS << uint8_t((AddrDelta >> 16) & 0xff); OS << uint8_t((AddrDelta >> 24) & 0xff); } }