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From Craig Silverstein: rework DWARF reader code a bit.

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This commit is contained in:
Ian Lance Taylor 2007-11-12 19:56:20 +00:00
parent 386c048c7a
commit 24badc6562
3 changed files with 88 additions and 78 deletions
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78
gold/dwarf_reader.cc
View File

@ -24,6 +24,7 @@
#include "elfcpp_swap.h"
#include "dwarf.h"
#include "object.h"
#include "reloc.h"
#include "dwarf_reader.h"
@ -115,6 +116,72 @@ ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
lsm->end_sequence = false;
}
template<int size, bool big_endian>
Dwarf_line_info<size, big_endian>::Dwarf_line_info(
Sized_relobj<size, big_endian>* object)
: data_valid_(true), buffer_(NULL), symtab_buffer_(NULL),
directories_(1), files_(1)
{
unsigned int debug_shndx;
for (debug_shndx = 0; debug_shndx < object->shnum(); ++debug_shndx)
if (object->section_name(debug_shndx) == ".debug_line")
{
off_t buffer_size;
this->buffer_ = object->section_contents(
debug_shndx, &buffer_size, false);
this->buffer_end_ = this->buffer_ + buffer_size;
break;
}
if (this->buffer_ == NULL)
{
this->data_valid_ = false;
return;
}
// Find the relocation section for ".debug_line".
bool got_relocs = false;
for (unsigned int reloc_shndx = 0;
reloc_shndx < object->shnum();
++reloc_shndx)
{
unsigned int reloc_sh_type = object->section_type(reloc_shndx);
if ((reloc_sh_type == elfcpp::SHT_REL
|| reloc_sh_type == elfcpp::SHT_RELA)
&& object->section_info(reloc_shndx) == debug_shndx)
{
got_relocs = this->track_relocs_.initialize(object, reloc_shndx,
reloc_sh_type);
break;
}
}
if (!got_relocs)
{
this->data_valid_ = false;
return;
}
// Finally, we need the symtab section to interpret the relocs.
unsigned int symtab_shndx;
for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
{
off_t symtab_size;
this->symtab_buffer_ = object->section_contents(
symtab_shndx, &symtab_size, false);
this->symtab_buffer_end_ = this->symtab_buffer_ + symtab_size;
break;
}
if (this->symtab_buffer_ == NULL)
{
this->data_valid_ = false;
return;
}
// Now that we have successfully read all the data, parse the debug
// info.
this->read_line_mappings();
}
// Read the DWARF header.
template<int size, bool big_endian>
@ -366,7 +433,7 @@ Dwarf_line_info<size, big_endian>::process_one_opcode(
this->data_valid_ = false;
}
break;
}
}
case elfcpp::DW_LNE_define_file:
{
const char* filename = reinterpret_cast<const char*>(start);
@ -475,12 +542,12 @@ Dwarf_line_info<size, big_endian>::read_relocs()
typename elfcpp::Elf_types<size>::Elf_Addr value;
off_t reloc_offset;
while ((reloc_offset = this->track_relocs_->next_offset()) != -1)
while ((reloc_offset = this->track_relocs_.next_offset()) != -1)
{
const unsigned int sym = this->track_relocs_->next_symndx();
const unsigned int sym = this->track_relocs_.next_symndx();
const unsigned int shndx = this->symbol_section(sym, &value);
this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
this->track_relocs_->advance(reloc_offset + 1);
this->track_relocs_.advance(reloc_offset + 1);
}
}
@ -490,6 +557,9 @@ template<int size, bool big_endian>
void
Dwarf_line_info<size, big_endian>::read_line_mappings()
{
if (this->data_valid_ == false)
return;
read_relocs();
while (this->buffer_ < this->buffer_end_)
{

34
gold/dwarf_reader.h
View File

@ -29,6 +29,7 @@
#include "elfcpp.h"
#include "elfcpp_swap.h"
#include "dwarf.h"
#include "reloc.h"
namespace gold
{
@ -44,25 +45,8 @@ template<int size, bool big_endian>
class Dwarf_line_info
{
public:
// Initializes a .debug_line reader. Buffer and buffer length point
// to the beginning and length of the line information to read.
// Reader is a ByteReader class that has the endianness set
// properly.
Dwarf_line_info(const unsigned char* buffer, off_t buffer_length,
Track_relocs<size, big_endian>* track_relocs,
const unsigned char* symtab_buffer,
off_t symtab_buffer_length)
: data_valid_(true),
buffer_(buffer), buffer_end_(buffer + buffer_length),
track_relocs_(track_relocs),
symtab_buffer_(symtab_buffer),
symtab_buffer_end_(symtab_buffer + symtab_buffer_length),
directories_(1), files_(1)
{ }
// Start processing line info, and populates the offset_map_.
void
read_line_mappings();
// Initializes a .debug_line reader for a given object file.
Dwarf_line_info(Sized_relobj<size, big_endian>* object);
// Given a section number and an offset, returns the associated
// file and line-number, as a string: "file:lineno". If unable
@ -72,6 +56,10 @@ class Dwarf_line_info
addr2line(unsigned int shndx, off_t offset);
private:
// Start processing line info, and populates the offset_map_.
void
read_line_mappings();
// Reads the relocation section associated with .debug_line and
// stores relocation information in reloc_map_.
void
@ -128,14 +116,14 @@ class Dwarf_line_info
// buffer is the buffer for our line info, starting at exactly where
// the line info to read is.
const unsigned char* buffer_;
const unsigned char* const buffer_end_;
const unsigned char* buffer_end_;
// This has relocations that point into buffer.
Track_relocs<size, big_endian>* track_relocs_;
Track_relocs<size, big_endian> track_relocs_;
// This is used to figure out what section to apply a relocation to.
const unsigned char* const symtab_buffer_;
const unsigned char* const symtab_buffer_end_;
const unsigned char* symtab_buffer_;
const unsigned char* symtab_buffer_end_;
// Holds the directories and files as we see them.
std::vector<std::string> directories_;

54
gold/object.cc
View File

@ -1093,57 +1093,9 @@ Relocate_info<size, big_endian>::location(size_t, off_t offset) const
std::string filename;
std::string file_and_lineno; // Better than filename-only, if available.
// The line-number information is in the ".debug_line" section.
unsigned int debug_shndx;
off_t debuglines_size;
const unsigned char* debuglines = NULL;
for (debug_shndx = 0; debug_shndx < this->object->shnum(); ++debug_shndx)
if (this->object->section_name(debug_shndx) == ".debug_line")
{
debuglines = this->object->section_contents(
debug_shndx, &debuglines_size, false);
break;
}
// Find the relocation section for ".debug_line".
Track_relocs<size, big_endian> track_relocs;
bool got_relocs = false;
for (unsigned int reloc_shndx = 0;
reloc_shndx < this->object->shnum();
++reloc_shndx)
{
unsigned int reloc_sh_type = this->object->section_type(reloc_shndx);
if ((reloc_sh_type == elfcpp::SHT_REL
|| reloc_sh_type == elfcpp::SHT_RELA)
&& this->object->section_info(reloc_shndx) == debug_shndx)
{
got_relocs = track_relocs.initialize(this->object, reloc_shndx,
reloc_sh_type);
break;
}
}
// Finally, we need the symtab section to interpret the relocs.
unsigned int symtab_shndx;
off_t symtab_size;
const unsigned char* symtab = NULL;
for (symtab_shndx = 0; symtab_shndx < this->object->shnum(); ++symtab_shndx)
if (this->object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
{
symtab = this->object->section_contents(
symtab_shndx, &symtab_size, false);
break;
}
// If we got all three sections we need, we can try to read debug info.
if (debuglines != NULL && got_relocs && symtab != NULL)
{
Dwarf_line_info<size, big_endian> line_info(debuglines, debuglines_size,
&track_relocs,
symtab, symtab_size);
line_info.read_line_mappings();
file_and_lineno = line_info.addr2line(this->data_shndx, offset);
}
Dwarf_line_info<size, big_endian> line_info(this->object);
// This will be "" if we failed to parse the debug info for any reason.
file_and_lineno = line_info.addr2line(this->data_shndx, offset);
std::string ret(this->object->name());
ret += ':';