gold/dwarf_reader.h

   1 // dwarf_reader.h -- parse dwarf2/3 debug information for gold  -*- C++ -*-
   2
   3 // Copyright 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #ifndef GOLD_DWARF_READER_H
  24 #define GOLD_DWARF_READER_H
  25
  26 #include <vector>
  27
  28 #include "elfcpp_swap.h"
  29 #include "dwarf.h"
  30
  31 namespace gold
  32 {
  33
  34 struct LineStateMachine;
  35
  36 // This class is used to read the line information from the debugging
  37 // section of an object file.
  38
  39 template<int size, bool big_endian>
  40 class Dwarf_line_info
  41 {
  42  public:
  43   // Initializes a .debug_line reader. Buffer and buffer length point
  44   // to the beginning and length of the line information to read.
  45   // Reader is a ByteReader class that has the endianness set
  46   // properly.
  47   Dwarf_line_info(const unsigned char* buffer, off_t buffer_length)
  48     : buffer_(buffer), buffer_end_(buffer + buffer_length),
  49       directories_(1), files_(1)
  50   { }
  51
  52   // Start processing line info, and populates the offset_map_.
  53   void
  54   read_line_mappings();
  55
  56   // Given a section number and an offset, returns the associated
  57   // file and line-number, as a string: "file:lineno".  If unable
  58   // to do the mapping, returns the empty string.  You must call
  59   // read_line_mappings() before calling this function.
  60   std::string
  61   addr2line(unsigned int shndx, off_t offset);
  62
  63  private:
  64   // Reads the DWARF2/3 header for this line info.  Each takes as input
  65   // a starting buffer position, and returns the ending position.
  66   const unsigned char*
  67   read_header_prolog(const unsigned char* lineptr);
  68
  69   const unsigned char*
  70   read_header_tables(const unsigned char* lineptr);
  71
  72   // Reads the DWARF2/3 line information.
  73   const unsigned char*
  74   read_lines(const unsigned char* lineptr);
  75
  76   // Process a single line info opcode at START using the state
  77   // machine at LSM.  Return true if we should define a line using the
  78   // current state of the line state machine.  Place the length of the
  79   // opcode in LEN.
  80   bool
  81   process_one_opcode(const unsigned char* start,
  82                      struct LineStateMachine* lsm, size_t* len);
  83
  84   // A DWARF2/3 line info header.  This is not the same size as in the
  85   // actual file, as the one in the file may have a 32 bit or 64 bit
  86   // lengths.
  87
  88   struct Dwarf_line_infoHeader
  89   {
  90     off_t total_length;
  91     int version;
  92     off_t prologue_length;
  93     int min_insn_length; // insn stands for instructin
  94     bool default_is_stmt; // stmt stands for statement
  95     signed char line_base;
  96     int line_range;
  97     unsigned char opcode_base;
  98     std::vector<unsigned char> std_opcode_lengths;
  99     int offset_size;
 100   } header_;
 101
 102   // buffer is the buffer for our line info, starting at exactly where
 103   // the line info to read is.
 104   const unsigned char* buffer_;
 105   const unsigned char* const buffer_end_;
 106
 107   // Holds the directories and files as we see them.
 108   std::vector<std::string> directories_;
 109   // The first part is an index into directories_, the second the filename.
 110   std::vector< std::pair<int, std::string> > files_;
 111
 112   // We can't do better than to keep the offsets in a sorted vector.
 113   // Here, offset is the key, and file_num/line_num is the value.
 114   struct Offset_to_lineno_entry
 115   {
 116     off_t offset;
 117     int file_num;    // a pointer into files_
 118     int line_num;
 119     // Offsets are unique within a section, so that's a sufficient sort key.
 120     bool operator<(const Offset_to_lineno_entry& that) const
 121     { return this->offset < that.offset; }
 122   };
 123   // We have a vector of offset->lineno entries for every input section.
 124   typedef Unordered_map<unsigned int, std::vector<Offset_to_lineno_entry> >
 125   Lineno_map;
 126
 127   Lineno_map line_number_map_;
 128 };
 129
 130 } // End namespace gold.
 131
 132 #endif // !defined(GOLD_DWARF_READER_H)