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llvm-6502/lib/DebugInfo/DWARFDebugLine.cpp
Alexey Samsonov 351f83be64 Fix the representation of debug line table in DebugInfo LLVM library, 
and "instruction address -> file/line" lookup.

Instead of plain collection of rows, debug line table for compilation unit is now
treated as the number of row ranges, describing sequences (series of contiguous machine
instructions). The sequences are not always listed in the order of increasing
address, so previously used std::lower_bound() sometimes produced wrong results.
Now the instruction address lookup consists of two stages: finding the correct
sequence, and searching for address in range of rows for this sequence.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161414 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-07 11:46:57 +00:00

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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 "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] %4" PRIu64 " ", i+1, fileEntry.DirIdx)
<< format("0x%8.8" PRIx64 " 0x%8.8" PRIx64 " ",
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%16.16" PRIx64 " %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) {
if (Sequence::Empty) {
// Record the beginning of instruction sequence.
Sequence::Empty = false;
Sequence::LowPC = Address;
Sequence::FirstRowIndex = row;
}
++row; // Increase the row number.
LineTable::appendRow(*this);
if (EndSequence) {
// Record the end of instruction sequence.
Sequence::HighPC = Address;
Sequence::LastRowIndex = row;
if (Sequence::isValid())
LineTable::appendSequence(*this);
Sequence::reset();
}
Row::postAppend();
}
void DWARFDebugLine::State::finalize() {
row = DoneParsingLineTable;
if (!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).
}
}
DWARFDebugLine::DumpingState::~DumpingState() {}
void DWARFDebugLine::DumpingState::finalize() {
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 false;
}
return true;
}
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();
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;
}
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