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1 // dwarf_reader.h -- parse dwarf2/3 debug information for gold -*- C++ -*-
3 // Copyright 2007, 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
23 #ifndef GOLD_DWARF_READER_H
24 #define GOLD_DWARF_READER_H
26 #include <vector>
27 #include <map>
29 #include "elfcpp.h"
30 #include "elfcpp_swap.h"
31 #include "dwarf.h"
32 #include "reloc.h"
34 namespace gold
37 template<int size, bool big_endian>
38 class Track_relocs;
39 struct LineStateMachine;
41 // We can't do better than to keep the offsets in a sorted vector.
42 // Here, offset is the key, and file_num/line_num is the value.
43 struct Offset_to_lineno_entry
45 off_t offset;
46 int header_num; // which file-list to use (i.e. which .o file are we in)
47 int file_num; // a pointer into files_
48 int line_num; // the line number in the source file
49 // Offsets are unique within a section, so that's a sufficient sort key.
50 bool operator<(const Offset_to_lineno_entry& that) const
51 { return this->offset < that.offset; }
54 // This class is used to read the line information from the debugging
55 // section of an object file.
57 class Dwarf_line_info
59 public:
60 Dwarf_line_info()
61 { }
63 virtual
64 ~Dwarf_line_info()
65 { }
67 // Given a section number and an offset, returns the associated
68 // file and line-number, as a string: "file:lineno". If unable
69 // to do the mapping, returns the empty string. You must call
70 // read_line_mappings() before calling this function.
71 std::string
72 addr2line(unsigned int shndx, off_t offset)
73 { return do_addr2line(shndx, offset); }
75 // A helper function for a single addr2line lookup. It uses
76 // parameters() to figure out the size and endianness. This is less
77 // efficient than using the templatized size and endianness, so only
78 // call this from an un-templatized context.
79 static std::string
80 one_addr2line(Object* object, unsigned int shndx, off_t offset);
82 private:
83 virtual std::string
84 do_addr2line(unsigned int shndx, off_t offset) = 0;
87 template<int size, bool big_endian>
88 class Sized_dwarf_line_info : public Dwarf_line_info
90 public:
91 // Initializes a .debug_line reader for a given object file.
92 // If SHNDX is specified and non-negative, only read the debug
93 // information that pertains to the specified section.
94 Sized_dwarf_line_info(Object* object, off_t read_shndx = -1U);
96 private:
97 std::string
98 do_addr2line(unsigned int shndx, off_t offset);
100 // Start processing line info, and populates the offset_map_.
101 // If SHNDX is non-negative, only store debug information that
102 // pertains to the specified section.
103 void
104 read_line_mappings(off_t shndx);
106 // Reads the relocation section associated with .debug_line and
107 // stores relocation information in reloc_map_.
108 void
109 read_relocs();
111 // Looks in the symtab to see what section a symbol is in.
112 unsigned int
113 symbol_section(unsigned int sym,
114 typename elfcpp::Elf_types<size>::Elf_Addr* value);
116 // Reads the DWARF2/3 header for this line info. Each takes as input
117 // a starting buffer position, and returns the ending position.
118 const unsigned char*
119 read_header_prolog(const unsigned char* lineptr);
121 const unsigned char*
122 read_header_tables(const unsigned char* lineptr);
124 // Reads the DWARF2/3 line information. If shndx is non-negative,
125 // discard all line information that doesn't pertain to the given
126 // section.
127 const unsigned char*
128 read_lines(const unsigned char* lineptr, off_t shndx);
130 // Process a single line info opcode at START using the state
131 // machine at LSM. Return true if we should define a line using the
132 // current state of the line state machine. Place the length of the
133 // opcode in LEN.
134 bool
135 process_one_opcode(const unsigned char* start,
136 struct LineStateMachine* lsm, size_t* len);
138 // Some parts of processing differ depending on whether the input
139 // was a .o file or not.
140 bool input_is_relobj();
142 // If we saw anything amiss while parsing, we set this to false.
143 // Then addr2line will always fail (rather than return possibly-
144 // corrupt data).
145 bool data_valid_;
147 // A DWARF2/3 line info header. This is not the same size as in the
148 // actual file, as the one in the file may have a 32 bit or 64 bit
149 // lengths.
151 struct Dwarf_line_infoHeader
153 off_t total_length;
154 int version;
155 off_t prologue_length;
156 int min_insn_length; // insn stands for instructin
157 bool default_is_stmt; // stmt stands for statement
158 signed char line_base;
159 int line_range;
160 unsigned char opcode_base;
161 std::vector<unsigned char> std_opcode_lengths;
162 int offset_size;
163 } header_;
165 // buffer is the buffer for our line info, starting at exactly where
166 // the line info to read is.
167 const unsigned char* buffer_;
168 const unsigned char* buffer_end_;
170 // This has relocations that point into buffer.
171 Track_relocs<size, big_endian> track_relocs_;
173 // This is used to figure out what section to apply a relocation to.
174 const unsigned char* symtab_buffer_;
175 section_size_type symtab_buffer_size_;
177 // Holds the directories and files as we see them. We have an array
178 // of directory-lists, one for each .o file we're reading (usually
179 // there will just be one, but there may be more if input is a .so).
180 std::vector<std::vector<std::string> > directories_;
181 // The first part is an index into directories_, the second the filename.
182 std::vector<std::vector< std::pair<int, std::string> > > files_;
184 // An index into the current directories_ and files_ vectors.
185 int current_header_index_;
187 // A sorted map from offset of the relocation target to the shndx
188 // and addend for the relocation.
189 typedef std::map<typename elfcpp::Elf_types<size>::Elf_Addr,
190 std::pair<unsigned int,
191 typename elfcpp::Elf_types<size>::Elf_Swxword> >
192 Reloc_map;
193 Reloc_map reloc_map_;
195 // We have a vector of offset->lineno entries for every input section.
196 typedef Unordered_map<unsigned int, std::vector<Offset_to_lineno_entry> >
197 Lineno_map;
199 Lineno_map line_number_map_;
202 } // End namespace gold.
204 #endif // !defined(GOLD_DWARF_READER_H)