1 /* DWARF 2 debugging format support for GDB.
3 Copyright (C) 1994-2022 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20 #ifndef DWARF2_LINE_HEADER_H
21 #define DWARF2_LINE_HEADER_H
25 /* dir_index is 1-based in DWARF 4 and before, and is 0-based in DWARF 5 and
27 typedef int dir_index;
29 /* file_name_index is 1-based in DWARF 4 and before, and is 0-based in DWARF 5
31 typedef int file_name_index;
37 file_entry () = default;
39 file_entry (const char *name_, file_name_index index_, dir_index d_index_,
40 unsigned int mod_time_, unsigned int length_)
48 /* Return the include directory at D_INDEX stored in LH. Returns
49 NULL if D_INDEX is out of bounds. */
50 const char *include_dir (const line_header *lh) const;
52 /* The file name. Note this is an observing pointer. The memory is
53 owned by debug_line_buffer. */
56 /* The index of this file in the file table. */
57 file_name_index index {};
59 /* The directory index (1-based). */
62 unsigned int mod_time {};
64 unsigned int length {};
66 /* The associated symbol table, if any. */
67 struct symtab *symtab {};
70 /* The line number information for a compilation unit (found in the
71 .debug_line section) begins with a "statement program header",
72 which contains the following information. */
75 /* COMP_DIR is the value of the DW_AT_comp_dir attribute of the compilation
76 unit in the context of which we are reading this line header, or nullptr
77 if unknown or not applicable. */
78 explicit line_header (const char *comp_dir)
79 : offset_in_dwz {}, m_comp_dir (comp_dir)
82 /* This constructor should only be used to create line_header intances to do
83 hash table lookups. */
84 line_header (sect_offset sect_off, bool offset_in_dwz)
85 : sect_off (sect_off),
86 offset_in_dwz (offset_in_dwz)
89 /* Add an entry to the include directory table. */
90 void add_include_dir (const char *include_dir);
92 /* Add an entry to the file name table. */
93 void add_file_name (const char *name, dir_index d_index,
94 unsigned int mod_time, unsigned int length);
96 /* Return the include dir at INDEX (0-based in DWARF 5 and 1-based before).
97 Returns NULL if INDEX is out of bounds. */
98 const char *include_dir_at (dir_index index) const
104 vec_index = index - 1;
105 if (vec_index < 0 || vec_index >= m_include_dirs.size ())
107 return m_include_dirs[vec_index];
110 bool is_valid_file_index (int file_index) const
113 return 0 <= file_index && file_index < file_names_size ();
114 return 1 <= file_index && file_index <= file_names_size ();
117 /* Return the file name at INDEX (0-based in DWARF 5 and 1-based before).
118 Returns NULL if INDEX is out of bounds. */
119 file_entry *file_name_at (file_name_index index)
125 vec_index = index - 1;
126 if (vec_index < 0 || vec_index >= m_file_names.size ())
128 return &m_file_names[vec_index];
131 /* A const overload of the same. */
132 const file_entry *file_name_at (file_name_index index) const
134 line_header *lh = const_cast<line_header *> (this);
135 return lh->file_name_at (index);
138 /* The indexes are 0-based in DWARF 5 and 1-based in DWARF 4. Therefore,
139 this method should only be used to iterate through all file entries in an
140 index-agnostic manner. */
141 std::vector<file_entry> &file_names ()
142 { return m_file_names; }
143 /* A const overload of the same. */
144 const std::vector<file_entry> &file_names () const
145 { return m_file_names; }
147 /* Offset of line number information in .debug_line section. */
148 sect_offset sect_off {};
150 /* OFFSET is for struct dwz_file associated with dwarf2_per_objfile. */
151 unsigned offset_in_dwz : 1; /* Can't initialize bitfields in-class. */
153 unsigned short version {};
154 unsigned char minimum_instruction_length {};
155 unsigned char maximum_ops_per_instruction {};
156 unsigned char default_is_stmt {};
158 unsigned char line_range {};
159 unsigned char opcode_base {};
161 /* standard_opcode_lengths[i] is the number of operands for the
162 standard opcode whose value is i. This means that
163 standard_opcode_lengths[0] is unused, and the last meaningful
164 element is standard_opcode_lengths[opcode_base - 1]. */
165 std::unique_ptr<unsigned char[]> standard_opcode_lengths;
167 int file_names_size () const
168 { return m_file_names.size(); }
170 /* The start and end of the statement program following this
171 header. These point into dwarf2_per_objfile->line_buffer. */
172 const gdb_byte *statement_program_start {}, *statement_program_end {};
174 /* Return the most "complete" file name for FILE possible.
176 This means prepending the directory and compilation directory, as needed,
177 until we get an absolute path. */
178 std::string file_file_name (const file_entry &fe) const;
180 /* Return the compilation directory of the compilation unit in the context of
181 which this line header is read. Return nullptr if non applicable. */
182 const char *comp_dir () const
183 { return m_comp_dir; }
186 /* The include_directories table. Note these are observing
187 pointers. The memory is owned by debug_line_buffer. */
188 std::vector<const char *> m_include_dirs;
190 /* The file_names table. This is private because the meaning of indexes
191 differs among DWARF versions (The first valid index is 1 in DWARF 4 and
192 before, and is 0 in DWARF 5 and later). So the client should use
193 file_name_at method for access. */
194 std::vector<file_entry> m_file_names;
196 /* Compilation directory of the compilation unit in the context of which this
197 line header is read. nullptr if unknown or not applicable. */
198 const char *m_comp_dir = nullptr;
201 typedef std::unique_ptr<line_header> line_header_up;
204 file_entry::include_dir (const line_header *lh) const
206 return lh->include_dir_at (d_index);
209 /* Read the statement program header starting at SECT_OFF in SECTION.
210 Return line_header. Returns nullptr if there is a problem reading
211 the header, e.g., if it has a version we don't understand.
213 NOTE: the strings in the include directory and file name tables of
214 the returned object point into the dwarf line section buffer,
215 and must not be freed. */
217 extern line_header_up dwarf_decode_line_header
218 (sect_offset sect_off, bool is_dwz, dwarf2_per_objfile *per_objfile,
219 struct dwarf2_section_info *section, const struct comp_unit_head *cu_header,
220 const char *comp_dir);
222 #endif /* DWARF2_LINE_HEADER_H */