//===-- DWARFDebugLine.cpp ------------------------------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "llvm/DebugInfo/DWARFDebugLine.h" #include "llvm/Support/Dwarf.h" #include "llvm/Support/Format.h" #include "llvm/Support/Path.h" #include "llvm/Support/raw_ostream.h" #include using namespace llvm; using namespace dwarf; typedef DILineInfoSpecifier::FileLineInfoKind FileLineInfoKind; DWARFDebugLine::Prologue::Prologue() { clear(); } void DWARFDebugLine::Prologue::clear() { TotalLength = Version = PrologueLength = 0; MinInstLength = MaxOpsPerInst = DefaultIsStmt = LineBase = LineRange = 0; OpcodeBase = 0; StandardOpcodeLengths.clear(); IncludeDirectories.clear(); FileNames.clear(); } void DWARFDebugLine::Prologue::dump(raw_ostream &OS) const { OS << "Line table prologue:\n" << format(" total_length: 0x%8.8x\n", TotalLength) << format(" version: %u\n", Version) << format(" prologue_length: 0x%8.8x\n", PrologueLength) << format(" min_inst_length: %u\n", MinInstLength) << format(Version >= 4 ? "max_ops_per_inst: %u\n" : "", MaxOpsPerInst) << format(" default_is_stmt: %u\n", DefaultIsStmt) << format(" line_base: %i\n", LineBase) << format(" line_range: %u\n", LineRange) << format(" opcode_base: %u\n", OpcodeBase); for (uint32_t i = 0; i < StandardOpcodeLengths.size(); ++i) OS << format("standard_opcode_lengths[%s] = %u\n", LNStandardString(i+1), StandardOpcodeLengths[i]); if (!IncludeDirectories.empty()) for (uint32_t i = 0; i < IncludeDirectories.size(); ++i) OS << format("include_directories[%3u] = '", i+1) << IncludeDirectories[i] << "'\n"; if (!FileNames.empty()) { OS << " Dir Mod Time File Len File Name\n" << " ---- ---------- ---------- -----------" "----------------\n"; for (uint32_t i = 0; i < FileNames.size(); ++i) { const FileNameEntry& fileEntry = FileNames[i]; OS << format("file_names[%3u] %4" PRIu64 " ", i+1, fileEntry.DirIdx) << format("0x%8.8" PRIx64 " 0x%8.8" PRIx64 " ", fileEntry.ModTime, fileEntry.Length) << fileEntry.Name << '\n'; } } } bool DWARFDebugLine::Prologue::parse(DataExtractor debug_line_data, uint32_t *offset_ptr) { const uint32_t prologue_offset = *offset_ptr; clear(); TotalLength = debug_line_data.getU32(offset_ptr); Version = debug_line_data.getU16(offset_ptr); if (Version < 2) return false; PrologueLength = debug_line_data.getU32(offset_ptr); const uint32_t end_prologue_offset = PrologueLength + *offset_ptr; MinInstLength = debug_line_data.getU8(offset_ptr); if (Version >= 4) MaxOpsPerInst = debug_line_data.getU8(offset_ptr); DefaultIsStmt = debug_line_data.getU8(offset_ptr); LineBase = debug_line_data.getU8(offset_ptr); LineRange = debug_line_data.getU8(offset_ptr); OpcodeBase = debug_line_data.getU8(offset_ptr); StandardOpcodeLengths.reserve(OpcodeBase - 1); for (uint32_t i = 1; i < OpcodeBase; ++i) { uint8_t op_len = debug_line_data.getU8(offset_ptr); StandardOpcodeLengths.push_back(op_len); } while (*offset_ptr < end_prologue_offset) { const char *s = debug_line_data.getCStr(offset_ptr); if (s && s[0]) IncludeDirectories.push_back(s); else break; } while (*offset_ptr < end_prologue_offset) { const char *name = debug_line_data.getCStr(offset_ptr); if (name && name[0]) { FileNameEntry fileEntry; fileEntry.Name = name; fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr); fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr); fileEntry.Length = debug_line_data.getULEB128(offset_ptr); FileNames.push_back(fileEntry); } else { break; } } if (*offset_ptr != end_prologue_offset) { fprintf(stderr, "warning: parsing line table prologue at 0x%8.8x should" " have ended at 0x%8.8x but it ended at 0x%8.8x\n", prologue_offset, end_prologue_offset, *offset_ptr); return false; } return true; } DWARFDebugLine::Row::Row(bool default_is_stmt) { reset(default_is_stmt); } void DWARFDebugLine::Row::postAppend() { BasicBlock = false; PrologueEnd = false; EpilogueBegin = false; } void DWARFDebugLine::Row::reset(bool default_is_stmt) { Address = 0; Line = 1; Column = 0; File = 1; Isa = 0; Discriminator = 0; IsStmt = default_is_stmt; BasicBlock = false; EndSequence = false; PrologueEnd = false; EpilogueBegin = false; } void DWARFDebugLine::Row::dump(raw_ostream &OS) const { OS << format("0x%16.16" PRIx64 " %6u %6u", Address, Line, Column) << format(" %6u %3u %13u ", File, Isa, Discriminator) << (IsStmt ? " is_stmt" : "") << (BasicBlock ? " basic_block" : "") << (PrologueEnd ? " prologue_end" : "") << (EpilogueBegin ? " epilogue_begin" : "") << (EndSequence ? " end_sequence" : "") << '\n'; } DWARFDebugLine::Sequence::Sequence() { reset(); } void DWARFDebugLine::Sequence::reset() { LowPC = 0; HighPC = 0; FirstRowIndex = 0; LastRowIndex = 0; Empty = true; } DWARFDebugLine::LineTable::LineTable() { clear(); } void DWARFDebugLine::LineTable::dump(raw_ostream &OS) const { Prologue.dump(OS); OS << '\n'; if (!Rows.empty()) { OS << "Address Line Column File ISA Discriminator Flags\n" << "------------------ ------ ------ ------ --- ------------- " "-------------\n"; for (const Row &R : Rows) { R.dump(OS); } } } void DWARFDebugLine::LineTable::clear() { Prologue.clear(); Rows.clear(); Sequences.clear(); } DWARFDebugLine::ParsingState::ParsingState(struct LineTable *LT) : LineTable(LT), RowNumber(0) { resetRowAndSequence(); } void DWARFDebugLine::ParsingState::resetRowAndSequence() { Row.reset(LineTable->Prologue.DefaultIsStmt); Sequence.reset(); } void DWARFDebugLine::ParsingState::appendRowToMatrix(uint32_t offset) { if (Sequence.Empty) { // Record the beginning of instruction sequence. Sequence.Empty = false; Sequence.LowPC = Row.Address; Sequence.FirstRowIndex = RowNumber; } ++RowNumber; LineTable->appendRow(Row); if (Row.EndSequence) { // Record the end of instruction sequence. Sequence.HighPC = Row.Address; Sequence.LastRowIndex = RowNumber; if (Sequence.isValid()) LineTable->appendSequence(Sequence); Sequence.reset(); } Row.postAppend(); } const DWARFDebugLine::LineTable * DWARFDebugLine::getLineTable(uint32_t offset) const { LineTableConstIter pos = LineTableMap.find(offset); if (pos != LineTableMap.end()) return &pos->second; return nullptr; } const DWARFDebugLine::LineTable * DWARFDebugLine::getOrParseLineTable(DataExtractor debug_line_data, uint32_t offset) { std::pair pos = LineTableMap.insert(LineTableMapTy::value_type(offset, LineTable())); LineTable *LT = &pos.first->second; if (pos.second) { if (!LT->parse(debug_line_data, RelocMap, &offset)) return nullptr; } return LT; } bool DWARFDebugLine::LineTable::parse(DataExtractor debug_line_data, const RelocAddrMap *RMap, uint32_t *offset_ptr) { const uint32_t debug_line_offset = *offset_ptr; clear(); if (!Prologue.parse(debug_line_data, offset_ptr)) { // Restore our offset and return false to indicate failure! *offset_ptr = debug_line_offset; return false; } const uint32_t end_offset = debug_line_offset + Prologue.TotalLength + sizeof(Prologue.TotalLength); ParsingState State(this); while (*offset_ptr < end_offset) { uint8_t opcode = debug_line_data.getU8(offset_ptr); if (opcode == 0) { // Extended Opcodes always start with a zero opcode followed by // a uleb128 length so you can skip ones you don't know about uint32_t ext_offset = *offset_ptr; uint64_t len = debug_line_data.getULEB128(offset_ptr); uint32_t arg_size = len - (*offset_ptr - ext_offset); uint8_t sub_opcode = debug_line_data.getU8(offset_ptr); switch (sub_opcode) { case DW_LNE_end_sequence: // Set the end_sequence register of the state machine to true and // append a row to the matrix using the current values of the // state-machine registers. Then reset the registers to the initial // values specified above. Every statement program sequence must end // with a DW_LNE_end_sequence instruction which creates a row whose // address is that of the byte after the last target machine instruction // of the sequence. State.Row.EndSequence = true; State.appendRowToMatrix(*offset_ptr); State.resetRowAndSequence(); break; case DW_LNE_set_address: // Takes a single relocatable address as an operand. The size of the // operand is the size appropriate to hold an address on the target // machine. Set the address register to the value given by the // relocatable address. All of the other statement program opcodes // that affect the address register add a delta to it. This instruction // stores a relocatable value into it instead. { // If this address is in our relocation map, apply the relocation. RelocAddrMap::const_iterator AI = RMap->find(*offset_ptr); if (AI != RMap->end()) { const std::pair &R = AI->second; State.Row.Address = debug_line_data.getAddress(offset_ptr) + R.second; } else State.Row.Address = debug_line_data.getAddress(offset_ptr); } break; case DW_LNE_define_file: // Takes 4 arguments. The first is a null terminated string containing // a source file name. The second is an unsigned LEB128 number // representing the directory index of the directory in which the file // was found. The third is an unsigned LEB128 number representing the // time of last modification of the file. The fourth is an unsigned // LEB128 number representing the length in bytes of the file. The time // and length fields may contain LEB128(0) if the information is not // available. // // The directory index represents an entry in the include_directories // section of the statement program prologue. The index is LEB128(0) // if the file was found in the current directory of the compilation, // LEB128(1) if it was found in the first directory in the // include_directories section, and so on. The directory index is // ignored for file names that represent full path names. // // The files are numbered, starting at 1, in the order in which they // appear; the names in the prologue come before names defined by // the DW_LNE_define_file instruction. These numbers are used in the // the file register of the state machine. { FileNameEntry fileEntry; fileEntry.Name = debug_line_data.getCStr(offset_ptr); fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr); fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr); fileEntry.Length = debug_line_data.getULEB128(offset_ptr); Prologue.FileNames.push_back(fileEntry); } break; case DW_LNE_set_discriminator: State.Row.Discriminator = debug_line_data.getULEB128(offset_ptr); break; default: // Length doesn't include the zero opcode byte or the length itself, but // it does include the sub_opcode, so we have to adjust for that below (*offset_ptr) += arg_size; break; } } else if (opcode < Prologue.OpcodeBase) { switch (opcode) { // Standard Opcodes case DW_LNS_copy: // Takes no arguments. Append a row to the matrix using the // current values of the state-machine registers. Then set // the basic_block register to false. State.appendRowToMatrix(*offset_ptr); break; case DW_LNS_advance_pc: // Takes a single unsigned LEB128 operand, multiplies it by the // min_inst_length field of the prologue, and adds the // result to the address register of the state machine. State.Row.Address += debug_line_data.getULEB128(offset_ptr) * Prologue.MinInstLength; break; case DW_LNS_advance_line: // Takes a single signed LEB128 operand and adds that value to // the line register of the state machine. State.Row.Line += debug_line_data.getSLEB128(offset_ptr); break; case DW_LNS_set_file: // Takes a single unsigned LEB128 operand and stores it in the file // register of the state machine. State.Row.File = debug_line_data.getULEB128(offset_ptr); break; case DW_LNS_set_column: // Takes a single unsigned LEB128 operand and stores it in the // column register of the state machine. State.Row.Column = debug_line_data.getULEB128(offset_ptr); break; case DW_LNS_negate_stmt: // Takes no arguments. Set the is_stmt register of the state // machine to the logical negation of its current value. State.Row.IsStmt = !State.Row.IsStmt; break; case DW_LNS_set_basic_block: // Takes no arguments. Set the basic_block register of the // state machine to true State.Row.BasicBlock = true; break; case DW_LNS_const_add_pc: // Takes no arguments. Add to the address register of the state // machine the address increment value corresponding to special // opcode 255. The motivation for DW_LNS_const_add_pc is this: // when the statement program needs to advance the address by a // small amount, it can use a single special opcode, which occupies // a single byte. When it needs to advance the address by up to // twice the range of the last special opcode, it can use // DW_LNS_const_add_pc followed by a special opcode, for a total // of two bytes. Only if it needs to advance the address by more // than twice that range will it need to use both DW_LNS_advance_pc // and a special opcode, requiring three or more bytes. { uint8_t adjust_opcode = 255 - Prologue.OpcodeBase; uint64_t addr_offset = (adjust_opcode / Prologue.LineRange) * Prologue.MinInstLength; State.Row.Address += addr_offset; } break; case DW_LNS_fixed_advance_pc: // Takes a single uhalf operand. Add to the address register of // the state machine the value of the (unencoded) operand. This // is the only extended opcode that takes an argument that is not // a variable length number. The motivation for DW_LNS_fixed_advance_pc // is this: existing assemblers cannot emit DW_LNS_advance_pc or // special opcodes because they cannot encode LEB128 numbers or // judge when the computation of a special opcode overflows and // requires the use of DW_LNS_advance_pc. Such assemblers, however, // can use DW_LNS_fixed_advance_pc instead, sacrificing compression. State.Row.Address += debug_line_data.getU16(offset_ptr); break; case DW_LNS_set_prologue_end: // Takes no arguments. Set the prologue_end register of the // state machine to true State.Row.PrologueEnd = true; break; case DW_LNS_set_epilogue_begin: // Takes no arguments. Set the basic_block register of the // state machine to true State.Row.EpilogueBegin = true; break; case DW_LNS_set_isa: // Takes a single unsigned LEB128 operand and stores it in the // column register of the state machine. State.Row.Isa = debug_line_data.getULEB128(offset_ptr); break; default: // Handle any unknown standard opcodes here. We know the lengths // of such opcodes because they are specified in the prologue // as a multiple of LEB128 operands for each opcode. { assert(opcode - 1U < Prologue.StandardOpcodeLengths.size()); uint8_t opcode_length = Prologue.StandardOpcodeLengths[opcode - 1]; for (uint8_t i = 0; i < opcode_length; ++i) debug_line_data.getULEB128(offset_ptr); } break; } } else { // Special Opcodes // A special opcode value is chosen based on the amount that needs // to be added to the line and address registers. The maximum line // increment for a special opcode is the value of the line_base // field in the header, plus the value of the line_range field, // minus 1 (line base + line range - 1). If the desired line // increment is greater than the maximum line increment, a standard // opcode must be used instead of a special opcode. The "address // advance" is calculated by dividing the desired address increment // by the minimum_instruction_length field from the header. The // special opcode is then calculated using the following formula: // // opcode = (desired line increment - line_base) + // (line_range * address advance) + opcode_base // // If the resulting opcode is greater than 255, a standard opcode // must be used instead. // // To decode a special opcode, subtract the opcode_base from the // opcode itself to give the adjusted opcode. The amount to // increment the address register is the result of the adjusted // opcode divided by the line_range multiplied by the // minimum_instruction_length field from the header. That is: // // address increment = (adjusted opcode / line_range) * // minimum_instruction_length // // The amount to increment the line register is the line_base plus // the result of the adjusted opcode modulo the line_range. That is: // // line increment = line_base + (adjusted opcode % line_range) uint8_t adjust_opcode = opcode - Prologue.OpcodeBase; uint64_t addr_offset = (adjust_opcode / Prologue.LineRange) * Prologue.MinInstLength; int32_t line_offset = Prologue.LineBase + (adjust_opcode % Prologue.LineRange); State.Row.Line += line_offset; State.Row.Address += addr_offset; State.appendRowToMatrix(*offset_ptr); } } if (!State.Sequence.Empty) { fprintf(stderr, "warning: last sequence in debug line table is not" "terminated!\n"); } // Sort all sequences so that address lookup will work faster. if (!Sequences.empty()) { std::sort(Sequences.begin(), Sequences.end(), Sequence::orderByLowPC); // Note: actually, instruction address ranges of sequences should not // overlap (in shared objects and executables). If they do, the address // lookup would still work, though, but result would be ambiguous. // We don't report warning in this case. For example, // sometimes .so compiled from multiple object files contains a few // rudimentary sequences for address ranges [0x0, 0xsomething). } return end_offset; } uint32_t DWARFDebugLine::LineTable::lookupAddress(uint64_t address) const { uint32_t unknown_index = UINT32_MAX; if (Sequences.empty()) return unknown_index; // First, find an instruction sequence containing the given address. DWARFDebugLine::Sequence sequence; sequence.LowPC = address; SequenceIter first_seq = Sequences.begin(); SequenceIter last_seq = Sequences.end(); SequenceIter seq_pos = std::lower_bound(first_seq, last_seq, sequence, DWARFDebugLine::Sequence::orderByLowPC); DWARFDebugLine::Sequence found_seq; if (seq_pos == last_seq) { found_seq = Sequences.back(); } else if (seq_pos->LowPC == address) { found_seq = *seq_pos; } else { if (seq_pos == first_seq) return unknown_index; found_seq = *(seq_pos - 1); } if (!found_seq.containsPC(address)) return unknown_index; // Search for instruction address in the rows describing the sequence. // Rows are stored in a vector, so we may use arithmetical operations with // iterators. DWARFDebugLine::Row row; row.Address = address; RowIter first_row = Rows.begin() + found_seq.FirstRowIndex; RowIter last_row = Rows.begin() + found_seq.LastRowIndex; RowIter row_pos = std::lower_bound(first_row, last_row, row, DWARFDebugLine::Row::orderByAddress); if (row_pos == last_row) { return found_seq.LastRowIndex - 1; } uint32_t index = found_seq.FirstRowIndex + (row_pos - first_row); if (row_pos->Address > address) { if (row_pos == first_row) return unknown_index; else index--; } return index; } bool DWARFDebugLine::LineTable::lookupAddressRange( uint64_t address, uint64_t size, std::vector &result) const { if (Sequences.empty()) return false; uint64_t end_addr = address + size; // First, find an instruction sequence containing the given address. DWARFDebugLine::Sequence sequence; sequence.LowPC = address; SequenceIter first_seq = Sequences.begin(); SequenceIter last_seq = Sequences.end(); SequenceIter seq_pos = std::lower_bound(first_seq, last_seq, sequence, DWARFDebugLine::Sequence::orderByLowPC); if (seq_pos == last_seq || seq_pos->LowPC != address) { if (seq_pos == first_seq) return false; seq_pos--; } if (!seq_pos->containsPC(address)) return false; SequenceIter start_pos = seq_pos; // Add the rows from the first sequence to the vector, starting with the // index we just calculated while (seq_pos != last_seq && seq_pos->LowPC < end_addr) { DWARFDebugLine::Sequence cur_seq = *seq_pos; uint32_t first_row_index; uint32_t last_row_index; if (seq_pos == start_pos) { // For the first sequence, we need to find which row in the sequence is the // first in our range. Rows are stored in a vector, so we may use // arithmetical operations with iterators. DWARFDebugLine::Row row; row.Address = address; RowIter first_row = Rows.begin() + cur_seq.FirstRowIndex; RowIter last_row = Rows.begin() + cur_seq.LastRowIndex; RowIter row_pos = std::upper_bound(first_row, last_row, row, DWARFDebugLine::Row::orderByAddress); // The 'row_pos' iterator references the first row that is greater than // our start address. Unless that's the first row, we want to start at // the row before that. first_row_index = cur_seq.FirstRowIndex + (row_pos - first_row); if (row_pos != first_row) --first_row_index; } else first_row_index = cur_seq.FirstRowIndex; // For the last sequence in our range, we need to figure out the last row in // range. For all other sequences we can go to the end of the sequence. if (cur_seq.HighPC > end_addr) { DWARFDebugLine::Row row; row.Address = end_addr; RowIter first_row = Rows.begin() + cur_seq.FirstRowIndex; RowIter last_row = Rows.begin() + cur_seq.LastRowIndex; RowIter row_pos = std::upper_bound(first_row, last_row, row, DWARFDebugLine::Row::orderByAddress); // The 'row_pos' iterator references the first row that is greater than // our end address. The row before that is the last row we want. last_row_index = cur_seq.FirstRowIndex + (row_pos - first_row) - 1; } else // Contrary to what you might expect, DWARFDebugLine::SequenceLastRowIndex // isn't a valid index within the current sequence. It's that plus one. last_row_index = cur_seq.LastRowIndex - 1; for (uint32_t i = first_row_index; i <= last_row_index; ++i) { result.push_back(i); } ++seq_pos; } return true; } bool DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex, const char *CompDir, FileLineInfoKind Kind, std::string &Result) const { if (FileIndex == 0 || FileIndex > Prologue.FileNames.size() || Kind == FileLineInfoKind::None) return false; const FileNameEntry &Entry = Prologue.FileNames[FileIndex - 1]; const char *FileName = Entry.Name; if (Kind != FileLineInfoKind::AbsoluteFilePath || sys::path::is_absolute(FileName)) { Result = FileName; return true; } SmallString<16> FilePath; uint64_t IncludeDirIndex = Entry.DirIdx; const char *IncludeDir = ""; // Be defensive about the contents of Entry. if (IncludeDirIndex > 0 && IncludeDirIndex <= Prologue.IncludeDirectories.size()) IncludeDir = Prologue.IncludeDirectories[IncludeDirIndex - 1]; // We may still need to append compilation directory of compile unit. // We know that FileName is not absolute, the only way to have an // absolute path at this point would be if IncludeDir is absolute. if (CompDir && Kind == FileLineInfoKind::AbsoluteFilePath && sys::path::is_relative(IncludeDir)) sys::path::append(FilePath, CompDir); // sys::path::append skips empty strings. sys::path::append(FilePath, IncludeDir, FileName); Result = FilePath.str(); return true; } bool DWARFDebugLine::LineTable::getFileLineInfoForAddress(uint64_t Address, const char *CompDir, FileLineInfoKind Kind, DILineInfo &Result) const { // Get the index of row we're looking for in the line table. uint32_t RowIndex = lookupAddress(Address); if (RowIndex == -1U) return false; // Take file number and line/column from the row. const auto &Row = Rows[RowIndex]; if (!getFileNameByIndex(Row.File, CompDir, Kind, Result.FileName)) return false; Result.Line = Row.Line; Result.Column = Row.Column; return true; }