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llvm-project/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp

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//===-- 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/DWARF/DWARFDebugLine.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
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;
IsDWARF64 = false;
StandardOpcodeLengths.clear();
IncludeDirectories.clear();
FileNames.clear();
}
void DWARFDebugLine::Prologue::dump(raw_ostream &OS) const {
OS << "Line table prologue:\n"
<< format(" total_length: 0x%8.8" PRIx64 "\n", TotalLength)
<< format(" version: %u\n", Version)
<< format(" prologue_length: 0x%8.8" PRIx64 "\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 uint64_t prologue_offset = *offset_ptr;
clear();
TotalLength = debug_line_data.getU32(offset_ptr);
if (TotalLength == UINT32_MAX) {
IsDWARF64 = true;
TotalLength = debug_line_data.getU64(offset_ptr);
} else if (TotalLength > 0xffffff00) {
return false;
}
Version = debug_line_data.getU16(offset_ptr);
if (Version < 2)
return false;
PrologueLength =
debug_line_data.getUnsigned(offset_ptr, sizeofPrologueLength());
const uint64_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%8.8" PRIx64
" should have ended at 0x%8.8" PRIx64
" but it ended at 0x%8.8" PRIx64 "\n",
prologue_offset, end_prologue_offset, (uint64_t)*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<LineTableIter, bool> 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 + Prologue.sizeofTotalLength();
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<uint8_t, int64_t> &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);
// Reset discriminator to 0.
State.Row.Discriminator = 0;
}
}
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::findRowInSeq(const DWARFDebugLine::Sequence &seq,
uint64_t address) const {
if (!seq.containsPC(address))
return UnknownRowIndex;
// 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() + seq.FirstRowIndex;
RowIter last_row = Rows.begin() + seq.LastRowIndex;
LineTable::RowIter row_pos = std::lower_bound(
first_row, last_row, row, DWARFDebugLine::Row::orderByAddress);
if (row_pos == last_row) {
return seq.LastRowIndex - 1;
}
uint32_t index = seq.FirstRowIndex + (row_pos - first_row);
if (row_pos->Address > address) {
if (row_pos == first_row)
return UnknownRowIndex;
else
index--;
}
return index;
}
uint32_t DWARFDebugLine::LineTable::lookupAddress(uint64_t address) const {
if (Sequences.empty())
return UnknownRowIndex;
// 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 UnknownRowIndex;
found_seq = *(seq_pos - 1);
}
return findRowInSeq(found_seq, address);
}
bool DWARFDebugLine::LineTable::lookupAddressRange(
uint64_t address, uint64_t size, std::vector<uint32_t> &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) {
const DWARFDebugLine::Sequence &cur_seq = *seq_pos;
// For the first sequence, we need to find which row in the sequence is the
// first in our range.
uint32_t first_row_index = cur_seq.FirstRowIndex;
if (seq_pos == start_pos)
first_row_index = findRowInSeq(cur_seq, address);
// Figure out the last row in the range.
uint32_t last_row_index = findRowInSeq(cur_seq, end_addr - 1);
if (last_row_index == UnknownRowIndex)
last_row_index = cur_seq.LastRowIndex - 1;
assert(first_row_index != UnknownRowIndex);
assert(last_row_index != UnknownRowIndex);
for (uint32_t i = first_row_index; i <= last_row_index; ++i) {
result.push_back(i);
}
++seq_pos;
}
return true;
}
bool
DWARFDebugLine::LineTable::hasFileAtIndex(uint64_t FileIndex) const {
return FileIndex != 0 && FileIndex <= Prologue.FileNames.size();
}
bool
DWARFDebugLine::LineTable::getFileNameByIndex(uint64_t FileIndex,
const char *CompDir,
FileLineInfoKind Kind,
std::string &Result) const {
if (Kind == FileLineInfoKind::None || !hasFileAtIndex(FileIndex))
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;
}
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