//===-- DWARFDebugLine.cpp ------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "DWARFDebugLine.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
using namespace llvm;
using namespace dwarf;
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("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] %4u ", i+1, fileEntry.DirIdx)
<< format("0x%8.8x 0x%8.8x ", fileEntry.ModTime, fileEntry.Length)
<< fileEntry.Name << '\n';
}
}
}
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;
IsStmt = default_is_stmt;
BasicBlock = false;
EndSequence = false;
PrologueEnd = false;
EpilogueBegin = false;
}
void DWARFDebugLine::Row::dump(raw_ostream &OS) const {
OS << format("0x%16.16llx %6u %6u", Address, Line, Column)
<< format(" %6u %3u ", File, Isa)
<< (IsStmt ? " is_stmt" : "")
<< (BasicBlock ? " basic_block" : "")
<< (PrologueEnd ? " prologue_end" : "")
<< (EpilogueBegin ? " epilogue_begin" : "")
<< (EndSequence ? " end_sequence" : "")
<< '\n';
}
void DWARFDebugLine::LineTable::dump(raw_ostream &OS) const {
Prologue.dump(OS);
OS << '\n';
if (!Rows.empty()) {
OS << "Address Line Column File ISA Flags\n"
<< "------------------ ------ ------ ------ --- -------------\n";
for (std::vector<Row>::const_iterator pos = Rows.begin(),
end = Rows.end(); pos != end; ++pos)
pos->dump(OS);
}
}
DWARFDebugLine::State::~State() {}
void DWARFDebugLine::State::appendRowToMatrix(uint32_t offset) {
++row; // Increase the row number.
LineTable::appendRow(*this);
Row::postAppend();
}
DWARFDebugLine::DumpingState::~DumpingState() {}
void DWARFDebugLine::DumpingState::finalize(uint32_t offset) {
LineTable::dump(OS);
}
const DWARFDebugLine::LineTable *
DWARFDebugLine::getLineTable(uint32_t offset) const {
LineTableConstIter pos = LineTableMap.find(offset);
if (pos != LineTableMap.end())
return &pos->second;
return 0;
}
const DWARFDebugLine::LineTable *
DWARFDebugLine::getOrParseLineTable(DataExtractor debug_line_data,
uint32_t offset) {
std::pair<LineTableIter, bool> pos =
LineTableMap.insert(LineTableMapTy::value_type(offset, LineTable()));
if (pos.second) {
// Parse and cache the line table for at this offset.
State state;
if (!parseStatementTable(debug_line_data, &offset, state))
return 0;
pos.first->second = state;
}
return &pos.first->second;
}
bool
DWARFDebugLine::parsePrologue(DataExtractor debug_line_data,
uint32_t *offset_ptr, Prologue *prologue) {
const uint32_t prologue_offset = *offset_ptr;
prologue->clear();
prologue->TotalLength = debug_line_data.getU32(offset_ptr);
prologue->Version = debug_line_data.getU16(offset_ptr);
if (prologue->Version != 2)
return false;
prologue->PrologueLength = debug_line_data.getU32(offset_ptr);
const uint32_t end_prologue_offset = prologue->PrologueLength + *offset_ptr;
prologue->MinInstLength = debug_line_data.getU8(offset_ptr);
prologue->DefaultIsStmt = debug_line_data.getU8(offset_ptr);
prologue->LineBase = debug_line_data.getU8(offset_ptr);
prologue->LineRange = debug_line_data.getU8(offset_ptr);
prologue->OpcodeBase = debug_line_data.getU8(offset_ptr);
prologue->StandardOpcodeLengths.reserve(prologue->OpcodeBase-1);
for (uint32_t i = 1; i < prologue->OpcodeBase; ++i) {
uint8_t op_len = debug_line_data.getU8(offset_ptr);
prologue->StandardOpcodeLengths.push_back(op_len);
}
while (*offset_ptr < end_prologue_offset) {
const char *s = debug_line_data.getCStr(offset_ptr);
if (s && s[0])
prologue->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);
prologue->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 ad 0x%8.8x\n",
prologue_offset, end_prologue_offset, *offset_ptr);
}
return end_prologue_offset;
}
bool
DWARFDebugLine::parseStatementTable(DataExtractor debug_line_data,
uint32_t *offset_ptr, State &state) {
const uint32_t debug_line_offset = *offset_ptr;
Prologue *prologue = &state.Prologue;
if (!parsePrologue(debug_line_data, offset_ptr, prologue)) {
// 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);
state.reset();
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.EndSequence = true;
state.appendRowToMatrix(*offset_ptr);
state.reset();
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.
state.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;
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.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.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.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.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.IsStmt = !state.IsStmt;
break;
case DW_LNS_set_basic_block:
// Takes no arguments. Set the basic_block register of the
// state machine to true
state.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.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.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.PrologueEnd = true;
break;
case DW_LNS_set_epilogue_begin:
// Takes no arguments. Set the basic_block register of the
// state machine to true
state.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.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.Line += line_offset;
state.Address += addr_offset;
state.appendRowToMatrix(*offset_ptr);
}
}
state.finalize(*offset_ptr);
return end_offset;
}
static bool findMatchingAddress(const DWARFDebugLine::Row& row1,
const DWARFDebugLine::Row& row2) {
return row1.Address < row2.Address;
}
uint32_t
DWARFDebugLine::LineTable::lookupAddress(uint64_t address,
uint64_t cu_high_pc) const {
uint32_t index = UINT32_MAX;
if (!Rows.empty()) {
// Use the lower_bound algorithm to perform a binary search since we know
// that our line table data is ordered by address.
DWARFDebugLine::Row row;
row.Address = address;
typedef std::vector<Row>::const_iterator iterator;
iterator begin_pos = Rows.begin();
iterator end_pos = Rows.end();
iterator pos = std::lower_bound(begin_pos, end_pos, row,
findMatchingAddress);
if (pos == end_pos) {
if (address < cu_high_pc)
return Rows.size()-1;
} else {
// Rely on fact that we are using a std::vector and we can do
// pointer arithmetic to find the row index (which will be one less
// that what we found since it will find the first position after
// the current address) since std::vector iterators are just
// pointers to the container type.
index = pos - begin_pos;
if (pos->Address > address) {
if (index > 0)
--index;
else
index = UINT32_MAX;
}
}
}
return index; // Failed to find address.
}