1//===-- DWARFDebugLine.cpp ------------------------------------------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9 10#include "DWARFDebugLine.h" 11#include "llvm/Support/Dwarf.h" 12#include "llvm/Support/Format.h" 13#include "llvm/Support/Path.h" 14#include "llvm/Support/raw_ostream.h" 15#include <algorithm> 16using namespace llvm; 17using namespace dwarf; 18 19void DWARFDebugLine::Prologue::dump(raw_ostream &OS) const { 20 OS << "Line table prologue:\n" 21 << format(" total_length: 0x%8.8x\n", TotalLength) 22 << format(" version: %u\n", Version) 23 << format("prologue_length: 0x%8.8x\n", PrologueLength) 24 << format("min_inst_length: %u\n", MinInstLength) 25 << format("default_is_stmt: %u\n", DefaultIsStmt) 26 << format(" line_base: %i\n", LineBase) 27 << format(" line_range: %u\n", LineRange) 28 << format(" opcode_base: %u\n", OpcodeBase); 29 30 for (uint32_t i = 0; i < StandardOpcodeLengths.size(); ++i) 31 OS << format("standard_opcode_lengths[%s] = %u\n", LNStandardString(i+1), 32 StandardOpcodeLengths[i]); 33 34 if (!IncludeDirectories.empty()) 35 for (uint32_t i = 0; i < IncludeDirectories.size(); ++i) 36 OS << format("include_directories[%3u] = '", i+1) 37 << IncludeDirectories[i] << "'\n"; 38 39 if (!FileNames.empty()) { 40 OS << " Dir Mod Time File Len File Name\n" 41 << " ---- ---------- ---------- -----------" 42 "----------------\n"; 43 for (uint32_t i = 0; i < FileNames.size(); ++i) { 44 const FileNameEntry& fileEntry = FileNames[i]; 45 OS << format("file_names[%3u] %4" PRIu64 " ", i+1, fileEntry.DirIdx) 46 << format("0x%8.8" PRIx64 " 0x%8.8" PRIx64 " ", 47 fileEntry.ModTime, fileEntry.Length) 48 << fileEntry.Name << '\n'; 49 } 50 } 51} 52 53void DWARFDebugLine::Row::postAppend() { 54 BasicBlock = false; 55 PrologueEnd = false; 56 EpilogueBegin = false; 57} 58 59void DWARFDebugLine::Row::reset(bool default_is_stmt) { 60 Address = 0; 61 Line = 1; 62 Column = 0; 63 File = 1; 64 Isa = 0; 65 IsStmt = default_is_stmt; 66 BasicBlock = false; 67 EndSequence = false; 68 PrologueEnd = false; 69 EpilogueBegin = false; 70} 71 72void DWARFDebugLine::Row::dump(raw_ostream &OS) const { 73 OS << format("0x%16.16" PRIx64 " %6u %6u", Address, Line, Column) 74 << format(" %6u %3u ", File, Isa) 75 << (IsStmt ? " is_stmt" : "") 76 << (BasicBlock ? " basic_block" : "") 77 << (PrologueEnd ? " prologue_end" : "") 78 << (EpilogueBegin ? " epilogue_begin" : "") 79 << (EndSequence ? " end_sequence" : "") 80 << '\n'; 81} 82 83void DWARFDebugLine::LineTable::dump(raw_ostream &OS) const { 84 Prologue.dump(OS); 85 OS << '\n'; 86 87 if (!Rows.empty()) { 88 OS << "Address Line Column File ISA Flags\n" 89 << "------------------ ------ ------ ------ --- -------------\n"; 90 for (std::vector<Row>::const_iterator pos = Rows.begin(), 91 end = Rows.end(); pos != end; ++pos) 92 pos->dump(OS); 93 } 94} 95 96DWARFDebugLine::State::~State() {} 97 98void DWARFDebugLine::State::appendRowToMatrix(uint32_t offset) { 99 if (Sequence::Empty) { 100 // Record the beginning of instruction sequence. 101 Sequence::Empty = false; 102 Sequence::LowPC = Address; 103 Sequence::FirstRowIndex = row; 104 } 105 ++row; // Increase the row number. 106 LineTable::appendRow(*this); 107 if (EndSequence) { 108 // Record the end of instruction sequence. 109 Sequence::HighPC = Address; 110 Sequence::LastRowIndex = row; 111 if (Sequence::isValid()) 112 LineTable::appendSequence(*this); 113 Sequence::reset(); 114 } 115 Row::postAppend(); 116} 117 118void DWARFDebugLine::State::finalize() { 119 row = DoneParsingLineTable; 120 if (!Sequence::Empty) { 121 fprintf(stderr, "warning: last sequence in debug line table is not" 122 "terminated!\n"); 123 } 124 // Sort all sequences so that address lookup will work faster. 125 if (!Sequences.empty()) { 126 std::sort(Sequences.begin(), Sequences.end(), Sequence::orderByLowPC); 127 // Note: actually, instruction address ranges of sequences should not 128 // overlap (in shared objects and executables). If they do, the address 129 // lookup would still work, though, but result would be ambiguous. 130 // We don't report warning in this case. For example, 131 // sometimes .so compiled from multiple object files contains a few 132 // rudimentary sequences for address ranges [0x0, 0xsomething). 133 } 134} 135 136DWARFDebugLine::DumpingState::~DumpingState() {} 137 138void DWARFDebugLine::DumpingState::finalize() { 139 LineTable::dump(OS); 140} 141 142const DWARFDebugLine::LineTable * 143DWARFDebugLine::getLineTable(uint32_t offset) const { 144 LineTableConstIter pos = LineTableMap.find(offset); 145 if (pos != LineTableMap.end()) 146 return &pos->second; 147 return 0; 148} 149 150const DWARFDebugLine::LineTable * 151DWARFDebugLine::getOrParseLineTable(DataExtractor debug_line_data, 152 uint32_t offset) { 153 std::pair<LineTableIter, bool> pos = 154 LineTableMap.insert(LineTableMapTy::value_type(offset, LineTable())); 155 if (pos.second) { 156 // Parse and cache the line table for at this offset. 157 State state; 158 if (!parseStatementTable(debug_line_data, &offset, state)) 159 return 0; 160 pos.first->second = state; 161 } 162 return &pos.first->second; 163} 164 165bool 166DWARFDebugLine::parsePrologue(DataExtractor debug_line_data, 167 uint32_t *offset_ptr, Prologue *prologue) { 168 const uint32_t prologue_offset = *offset_ptr; 169 170 prologue->clear(); 171 prologue->TotalLength = debug_line_data.getU32(offset_ptr); 172 prologue->Version = debug_line_data.getU16(offset_ptr); 173 if (prologue->Version != 2) 174 return false; 175 176 prologue->PrologueLength = debug_line_data.getU32(offset_ptr); 177 const uint32_t end_prologue_offset = prologue->PrologueLength + *offset_ptr; 178 prologue->MinInstLength = debug_line_data.getU8(offset_ptr); 179 prologue->DefaultIsStmt = debug_line_data.getU8(offset_ptr); 180 prologue->LineBase = debug_line_data.getU8(offset_ptr); 181 prologue->LineRange = debug_line_data.getU8(offset_ptr); 182 prologue->OpcodeBase = debug_line_data.getU8(offset_ptr); 183 184 prologue->StandardOpcodeLengths.reserve(prologue->OpcodeBase-1); 185 for (uint32_t i = 1; i < prologue->OpcodeBase; ++i) { 186 uint8_t op_len = debug_line_data.getU8(offset_ptr); 187 prologue->StandardOpcodeLengths.push_back(op_len); 188 } 189 190 while (*offset_ptr < end_prologue_offset) { 191 const char *s = debug_line_data.getCStr(offset_ptr); 192 if (s && s[0]) 193 prologue->IncludeDirectories.push_back(s); 194 else 195 break; 196 } 197 198 while (*offset_ptr < end_prologue_offset) { 199 const char *name = debug_line_data.getCStr(offset_ptr); 200 if (name && name[0]) { 201 FileNameEntry fileEntry; 202 fileEntry.Name = name; 203 fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr); 204 fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr); 205 fileEntry.Length = debug_line_data.getULEB128(offset_ptr); 206 prologue->FileNames.push_back(fileEntry); 207 } else { 208 break; 209 } 210 } 211 212 if (*offset_ptr != end_prologue_offset) { 213 fprintf(stderr, "warning: parsing line table prologue at 0x%8.8x should" 214 " have ended at 0x%8.8x but it ended ad 0x%8.8x\n", 215 prologue_offset, end_prologue_offset, *offset_ptr); 216 return false; 217 } 218 return true; 219} 220 221bool 222DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data, 223 uint32_t *offset_ptr, State &state) { 224 const uint32_t debug_line_offset = *offset_ptr; 225 226 Prologue *prologue = &state.Prologue; 227 228 if (!parsePrologue(debug_line_data, offset_ptr, prologue)) { 229 // Restore our offset and return false to indicate failure! 230 *offset_ptr = debug_line_offset; 231 return false; 232 } 233 234 const uint32_t end_offset = debug_line_offset + prologue->TotalLength + 235 sizeof(prologue->TotalLength); 236 237 state.reset(); 238 239 while (*offset_ptr < end_offset) { 240 uint8_t opcode = debug_line_data.getU8(offset_ptr); 241 242 if (opcode == 0) { 243 // Extended Opcodes always start with a zero opcode followed by 244 // a uleb128 length so you can skip ones you don't know about 245 uint32_t ext_offset = *offset_ptr; 246 uint64_t len = debug_line_data.getULEB128(offset_ptr); 247 uint32_t arg_size = len - (*offset_ptr - ext_offset); 248 249 uint8_t sub_opcode = debug_line_data.getU8(offset_ptr); 250 switch (sub_opcode) { 251 case DW_LNE_end_sequence: 252 // Set the end_sequence register of the state machine to true and 253 // append a row to the matrix using the current values of the 254 // state-machine registers. Then reset the registers to the initial 255 // values specified above. Every statement program sequence must end 256 // with a DW_LNE_end_sequence instruction which creates a row whose 257 // address is that of the byte after the last target machine instruction 258 // of the sequence. 259 state.EndSequence = true; 260 state.appendRowToMatrix(*offset_ptr); 261 state.reset(); 262 break; 263 264 case DW_LNE_set_address: 265 // Takes a single relocatable address as an operand. The size of the 266 // operand is the size appropriate to hold an address on the target 267 // machine. Set the address register to the value given by the 268 // relocatable address. All of the other statement program opcodes 269 // that affect the address register add a delta to it. This instruction 270 // stores a relocatable value into it instead. 271 state.Address = debug_line_data.getAddress(offset_ptr); 272 break; 273 274 case DW_LNE_define_file: 275 // Takes 4 arguments. The first is a null terminated string containing 276 // a source file name. The second is an unsigned LEB128 number 277 // representing the directory index of the directory in which the file 278 // was found. The third is an unsigned LEB128 number representing the 279 // time of last modification of the file. The fourth is an unsigned 280 // LEB128 number representing the length in bytes of the file. The time 281 // and length fields may contain LEB128(0) if the information is not 282 // available. 283 // 284 // The directory index represents an entry in the include_directories 285 // section of the statement program prologue. The index is LEB128(0) 286 // if the file was found in the current directory of the compilation, 287 // LEB128(1) if it was found in the first directory in the 288 // include_directories section, and so on. The directory index is 289 // ignored for file names that represent full path names. 290 // 291 // The files are numbered, starting at 1, in the order in which they 292 // appear; the names in the prologue come before names defined by 293 // the DW_LNE_define_file instruction. These numbers are used in the 294 // the file register of the state machine. 295 { 296 FileNameEntry fileEntry; 297 fileEntry.Name = debug_line_data.getCStr(offset_ptr); 298 fileEntry.DirIdx = debug_line_data.getULEB128(offset_ptr); 299 fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr); 300 fileEntry.Length = debug_line_data.getULEB128(offset_ptr); 301 prologue->FileNames.push_back(fileEntry); 302 } 303 break; 304 305 default: 306 // Length doesn't include the zero opcode byte or the length itself, but 307 // it does include the sub_opcode, so we have to adjust for that below 308 (*offset_ptr) += arg_size; 309 break; 310 } 311 } else if (opcode < prologue->OpcodeBase) { 312 switch (opcode) { 313 // Standard Opcodes 314 case DW_LNS_copy: 315 // Takes no arguments. Append a row to the matrix using the 316 // current values of the state-machine registers. Then set 317 // the basic_block register to false. 318 state.appendRowToMatrix(*offset_ptr); 319 break; 320 321 case DW_LNS_advance_pc: 322 // Takes a single unsigned LEB128 operand, multiplies it by the 323 // min_inst_length field of the prologue, and adds the 324 // result to the address register of the state machine. 325 state.Address += debug_line_data.getULEB128(offset_ptr) * 326 prologue->MinInstLength; 327 break; 328 329 case DW_LNS_advance_line: 330 // Takes a single signed LEB128 operand and adds that value to 331 // the line register of the state machine. 332 state.Line += debug_line_data.getSLEB128(offset_ptr); 333 break; 334 335 case DW_LNS_set_file: 336 // Takes a single unsigned LEB128 operand and stores it in the file 337 // register of the state machine. 338 state.File = debug_line_data.getULEB128(offset_ptr); 339 break; 340 341 case DW_LNS_set_column: 342 // Takes a single unsigned LEB128 operand and stores it in the 343 // column register of the state machine. 344 state.Column = debug_line_data.getULEB128(offset_ptr); 345 break; 346 347 case DW_LNS_negate_stmt: 348 // Takes no arguments. Set the is_stmt register of the state 349 // machine to the logical negation of its current value. 350 state.IsStmt = !state.IsStmt; 351 break; 352 353 case DW_LNS_set_basic_block: 354 // Takes no arguments. Set the basic_block register of the 355 // state machine to true 356 state.BasicBlock = true; 357 break; 358 359 case DW_LNS_const_add_pc: 360 // Takes no arguments. Add to the address register of the state 361 // machine the address increment value corresponding to special 362 // opcode 255. The motivation for DW_LNS_const_add_pc is this: 363 // when the statement program needs to advance the address by a 364 // small amount, it can use a single special opcode, which occupies 365 // a single byte. When it needs to advance the address by up to 366 // twice the range of the last special opcode, it can use 367 // DW_LNS_const_add_pc followed by a special opcode, for a total 368 // of two bytes. Only if it needs to advance the address by more 369 // than twice that range will it need to use both DW_LNS_advance_pc 370 // and a special opcode, requiring three or more bytes. 371 { 372 uint8_t adjust_opcode = 255 - prologue->OpcodeBase; 373 uint64_t addr_offset = (adjust_opcode / prologue->LineRange) * 374 prologue->MinInstLength; 375 state.Address += addr_offset; 376 } 377 break; 378 379 case DW_LNS_fixed_advance_pc: 380 // Takes a single uhalf operand. Add to the address register of 381 // the state machine the value of the (unencoded) operand. This 382 // is the only extended opcode that takes an argument that is not 383 // a variable length number. The motivation for DW_LNS_fixed_advance_pc 384 // is this: existing assemblers cannot emit DW_LNS_advance_pc or 385 // special opcodes because they cannot encode LEB128 numbers or 386 // judge when the computation of a special opcode overflows and 387 // requires the use of DW_LNS_advance_pc. Such assemblers, however, 388 // can use DW_LNS_fixed_advance_pc instead, sacrificing compression. 389 state.Address += debug_line_data.getU16(offset_ptr); 390 break; 391 392 case DW_LNS_set_prologue_end: 393 // Takes no arguments. Set the prologue_end register of the 394 // state machine to true 395 state.PrologueEnd = true; 396 break; 397 398 case DW_LNS_set_epilogue_begin: 399 // Takes no arguments. Set the basic_block register of the 400 // state machine to true 401 state.EpilogueBegin = true; 402 break; 403 404 case DW_LNS_set_isa: 405 // Takes a single unsigned LEB128 operand and stores it in the 406 // column register of the state machine. 407 state.Isa = debug_line_data.getULEB128(offset_ptr); 408 break; 409 410 default: 411 // Handle any unknown standard opcodes here. We know the lengths 412 // of such opcodes because they are specified in the prologue 413 // as a multiple of LEB128 operands for each opcode. 414 { 415 assert(opcode - 1U < prologue->StandardOpcodeLengths.size()); 416 uint8_t opcode_length = prologue->StandardOpcodeLengths[opcode - 1]; 417 for (uint8_t i=0; i<opcode_length; ++i) 418 debug_line_data.getULEB128(offset_ptr); 419 } 420 break; 421 } 422 } else { 423 // Special Opcodes 424 425 // A special opcode value is chosen based on the amount that needs 426 // to be added to the line and address registers. The maximum line 427 // increment for a special opcode is the value of the line_base 428 // field in the header, plus the value of the line_range field, 429 // minus 1 (line base + line range - 1). If the desired line 430 // increment is greater than the maximum line increment, a standard 431 // opcode must be used instead of a special opcode. The "address 432 // advance" is calculated by dividing the desired address increment 433 // by the minimum_instruction_length field from the header. The 434 // special opcode is then calculated using the following formula: 435 // 436 // opcode = (desired line increment - line_base) + 437 // (line_range * address advance) + opcode_base 438 // 439 // If the resulting opcode is greater than 255, a standard opcode 440 // must be used instead. 441 // 442 // To decode a special opcode, subtract the opcode_base from the 443 // opcode itself to give the adjusted opcode. The amount to 444 // increment the address register is the result of the adjusted 445 // opcode divided by the line_range multiplied by the 446 // minimum_instruction_length field from the header. That is: 447 // 448 // address increment = (adjusted opcode / line_range) * 449 // minimum_instruction_length 450 // 451 // The amount to increment the line register is the line_base plus 452 // the result of the adjusted opcode modulo the line_range. That is: 453 // 454 // line increment = line_base + (adjusted opcode % line_range) 455 456 uint8_t adjust_opcode = opcode - prologue->OpcodeBase; 457 uint64_t addr_offset = (adjust_opcode / prologue->LineRange) * 458 prologue->MinInstLength; 459 int32_t line_offset = prologue->LineBase + 460 (adjust_opcode % prologue->LineRange); 461 state.Line += line_offset; 462 state.Address += addr_offset; 463 state.appendRowToMatrix(*offset_ptr); 464 } 465 } 466 467 state.finalize(); 468 469 return end_offset; 470} 471 472uint32_t 473DWARFDebugLine::LineTable::lookupAddress(uint64_t address) const { 474 uint32_t unknown_index = UINT32_MAX; 475 if (Sequences.empty()) 476 return unknown_index; 477 // First, find an instruction sequence containing the given address. 478 DWARFDebugLine::Sequence sequence; 479 sequence.LowPC = address; 480 SequenceIter first_seq = Sequences.begin(); 481 SequenceIter last_seq = Sequences.end(); 482 SequenceIter seq_pos = std::lower_bound(first_seq, last_seq, sequence, 483 DWARFDebugLine::Sequence::orderByLowPC); 484 DWARFDebugLine::Sequence found_seq; 485 if (seq_pos == last_seq) { 486 found_seq = Sequences.back(); 487 } else if (seq_pos->LowPC == address) { 488 found_seq = *seq_pos; 489 } else { 490 if (seq_pos == first_seq) 491 return unknown_index; 492 found_seq = *(seq_pos - 1); 493 } 494 if (!found_seq.containsPC(address)) 495 return unknown_index; 496 // Search for instruction address in the rows describing the sequence. 497 // Rows are stored in a vector, so we may use arithmetical operations with 498 // iterators. 499 DWARFDebugLine::Row row; 500 row.Address = address; 501 RowIter first_row = Rows.begin() + found_seq.FirstRowIndex; 502 RowIter last_row = Rows.begin() + found_seq.LastRowIndex; 503 RowIter row_pos = std::lower_bound(first_row, last_row, row, 504 DWARFDebugLine::Row::orderByAddress); 505 if (row_pos == last_row) { 506 return found_seq.LastRowIndex - 1; 507 } 508 uint32_t index = found_seq.FirstRowIndex + (row_pos - first_row); 509 if (row_pos->Address > address) { 510 if (row_pos == first_row) 511 return unknown_index; 512 else 513 index--; 514 } 515 return index; 516} 517 518bool 519DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex, 520 bool NeedsAbsoluteFilePath, 521 std::string &Result) const { 522 if (FileIndex == 0 || FileIndex > Prologue.FileNames.size()) 523 return false; 524 const FileNameEntry &Entry = Prologue.FileNames[FileIndex - 1]; 525 const char *FileName = Entry.Name; 526 if (!NeedsAbsoluteFilePath || 527 sys::path::is_absolute(FileName)) { 528 Result = FileName; 529 return true; 530 } 531 SmallString<16> FilePath; 532 uint64_t IncludeDirIndex = Entry.DirIdx; 533 // Be defensive about the contents of Entry. 534 if (IncludeDirIndex > 0 && 535 IncludeDirIndex <= Prologue.IncludeDirectories.size()) { 536 const char *IncludeDir = Prologue.IncludeDirectories[IncludeDirIndex - 1]; 537 sys::path::append(FilePath, IncludeDir); 538 } 539 sys::path::append(FilePath, FileName); 540 Result = FilePath.str(); 541 return true; 542} 543