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b8e6aad9 ILT |
1 | // merge.h -- handle section merging for gold -*- C++ -*- |
2 | ||
6cb15b7f ILT |
3 | // Copyright 2006, 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 | ||
b8e6aad9 ILT |
23 | #ifndef GOLD_MERGE_H |
24 | #define GOLD_MERGE_H | |
25 | ||
26 | #include <climits> | |
27 | ||
28 | #include "stringpool.h" | |
29 | #include "output.h" | |
30 | ||
31 | namespace gold | |
32 | { | |
33 | ||
730cdc88 | 34 | // This class manages mappings from input sections to offsets in an |
4625f782 ILT |
35 | // output section. This is used where input sections are merged. The |
36 | // actual data is stored in fields in Object. | |
730cdc88 ILT |
37 | |
38 | class Merge_map | |
39 | { | |
40 | public: | |
41 | Merge_map() | |
730cdc88 ILT |
42 | { } |
43 | ||
44 | // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in the | |
45 | // input section SHNDX in object OBJECT to OUTPUT_OFFSET in the | |
46 | // output section. An OUTPUT_OFFSET of -1 means that the bytes are | |
47 | // discarded. | |
48 | void | |
49 | add_mapping(Relobj* object, unsigned int shndx, off_t offset, off_t length, | |
50 | off_t output_offset); | |
51 | ||
52 | // Return the output offset for an input address. The input address | |
53 | // is at offset OFFSET in section SHNDX in OBJECT. This sets | |
54 | // *OUTPUT_OFFSET to the offset in the output section; this will be | |
55 | // -1 if the bytes are not being copied to the output. This returns | |
56 | // true if the mapping is known, false otherwise. | |
57 | bool | |
58 | get_output_offset(const Relobj* object, unsigned int shndx, off_t offset, | |
59 | off_t *output_offset) const; | |
730cdc88 ILT |
60 | }; |
61 | ||
b8e6aad9 ILT |
62 | // A general class for SHF_MERGE data, to hold functions shared by |
63 | // fixed-size constant data and string data. | |
64 | ||
65 | class Output_merge_base : public Output_section_data | |
66 | { | |
67 | public: | |
87f95776 ILT |
68 | Output_merge_base(uint64_t entsize, uint64_t addralign) |
69 | : Output_section_data(addralign), merge_map_(), entsize_(entsize) | |
b8e6aad9 ILT |
70 | { } |
71 | ||
730cdc88 | 72 | // Return the output offset for an input offset. |
b8e6aad9 | 73 | bool |
730cdc88 ILT |
74 | do_output_offset(const Relobj* object, unsigned int shndx, off_t offset, |
75 | off_t* poutput) const; | |
b8e6aad9 ILT |
76 | |
77 | protected: | |
78 | // Return the entry size. | |
79 | uint64_t | |
80 | entsize() const | |
81 | { return this->entsize_; } | |
82 | ||
83 | // Add a mapping from an OFFSET in input section SHNDX in object | |
84 | // OBJECT to an OUTPUT_OFFSET in the output section. | |
85 | void | |
86 | add_mapping(Relobj* object, unsigned int shndx, off_t offset, | |
730cdc88 | 87 | off_t length, off_t output_offset) |
b8e6aad9 | 88 | { |
730cdc88 ILT |
89 | this->merge_map_.add_mapping(object, shndx, offset, length, output_offset); |
90 | } | |
b8e6aad9 | 91 | |
730cdc88 | 92 | private: |
b8e6aad9 ILT |
93 | // A mapping from input object/section/offset to offset in output |
94 | // section. | |
95 | Merge_map merge_map_; | |
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96 | // The entry size. For fixed-size constants, this is the size of |
97 | // the constants. For strings, this is the size of a character. | |
98 | uint64_t entsize_; | |
99 | }; | |
100 | ||
101 | // Handle SHF_MERGE sections with fixed-size constant data. | |
102 | ||
103 | class Output_merge_data : public Output_merge_base | |
104 | { | |
105 | public: | |
87f95776 ILT |
106 | Output_merge_data(uint64_t entsize, uint64_t addralign) |
107 | : Output_merge_base(entsize, addralign), p_(NULL), len_(0), alc_(0), | |
b8e6aad9 ILT |
108 | hashtable_(128, Merge_data_hash(this), Merge_data_eq(this)) |
109 | { } | |
110 | ||
111 | // Add an input section. | |
112 | bool | |
113 | do_add_input_section(Relobj* object, unsigned int shndx); | |
114 | ||
115 | // Set the final data size. | |
116 | void | |
117 | do_set_address(uint64_t, off_t); | |
118 | ||
119 | // Write the data to the file. | |
120 | void | |
121 | do_write(Output_file*); | |
122 | ||
123 | private: | |
124 | // We build a hash table of the fixed-size constants. Each constant | |
125 | // is stored as a pointer into the section data we are accumulating. | |
126 | ||
127 | // A key in the hash table. This is an offset in the section | |
128 | // contents we are building. | |
129 | typedef off_t Merge_data_key; | |
130 | ||
131 | // Compute the hash code. To do this we need a pointer back to the | |
132 | // object holding the data. | |
133 | class Merge_data_hash | |
134 | { | |
135 | public: | |
136 | Merge_data_hash(const Output_merge_data* pomd) | |
137 | : pomd_(pomd) | |
138 | { } | |
139 | ||
140 | size_t | |
141 | operator()(Merge_data_key) const; | |
142 | ||
143 | private: | |
144 | const Output_merge_data* pomd_; | |
145 | }; | |
146 | ||
147 | friend class Merge_data_hash; | |
148 | ||
149 | // Compare two entries in the hash table for equality. To do this | |
150 | // we need a pointer back to the object holding the data. Note that | |
151 | // we now have a pointer to the object stored in two places in the | |
152 | // hash table. Fixing this would require specializing the hash | |
153 | // table, which would be hard to do portably. | |
154 | class Merge_data_eq | |
155 | { | |
156 | public: | |
157 | Merge_data_eq(const Output_merge_data* pomd) | |
158 | : pomd_(pomd) | |
159 | { } | |
160 | ||
161 | bool | |
162 | operator()(Merge_data_key k1, Merge_data_key k2) const; | |
163 | ||
164 | private: | |
165 | const Output_merge_data* pomd_; | |
166 | }; | |
167 | ||
168 | friend class Merge_data_eq; | |
169 | ||
170 | // The type of the hash table. | |
171 | typedef Unordered_set<Merge_data_key, Merge_data_hash, Merge_data_eq> | |
172 | Merge_data_hashtable; | |
173 | ||
174 | // Given a hash table key, which is just an offset into the section | |
175 | // data, return a pointer to the corresponding constant. | |
176 | const unsigned char* | |
177 | constant(Merge_data_key k) const | |
178 | { | |
179 | gold_assert(k >= 0 && k < this->len_); | |
180 | return this->p_ + k; | |
181 | } | |
182 | ||
183 | // Add a constant to the output. | |
184 | void | |
185 | add_constant(const unsigned char*); | |
186 | ||
187 | // The accumulated data. | |
188 | unsigned char* p_; | |
189 | // The length of the accumulated data. | |
190 | off_t len_; | |
191 | // The size of the allocated buffer. | |
192 | size_t alc_; | |
193 | // The hash table. | |
194 | Merge_data_hashtable hashtable_; | |
195 | }; | |
196 | ||
197 | // Handle SHF_MERGE sections with string data. This is a template | |
198 | // based on the type of the characters in the string. | |
199 | ||
200 | template<typename Char_type> | |
201 | class Output_merge_string : public Output_merge_base | |
202 | { | |
203 | public: | |
87f95776 ILT |
204 | Output_merge_string(uint64_t addralign) |
205 | : Output_merge_base(sizeof(Char_type), addralign), stringpool_(), | |
206 | merged_strings_() | |
207 | { | |
208 | gold_assert(addralign <= sizeof(Char_type)); | |
209 | this->stringpool_.set_no_zero_null(); | |
210 | } | |
b8e6aad9 ILT |
211 | |
212 | // Add an input section. | |
213 | bool | |
214 | do_add_input_section(Relobj* object, unsigned int shndx); | |
215 | ||
216 | // Set the final data size. | |
217 | void | |
218 | do_set_address(uint64_t, off_t); | |
219 | ||
220 | // Write the data to the file. | |
221 | void | |
222 | do_write(Output_file*); | |
223 | ||
224 | private: | |
225 | // As we see input sections, we build a mapping from object, section | |
226 | // index and offset to strings. | |
42e3fe0d | 227 | struct Merged_string |
b8e6aad9 | 228 | { |
42e3fe0d | 229 | // The input object where the string was found. |
b8e6aad9 | 230 | Relobj* object; |
42e3fe0d | 231 | // The input section in the input object. |
b8e6aad9 | 232 | unsigned int shndx; |
42e3fe0d | 233 | // The offset in the input section. |
b8e6aad9 | 234 | off_t offset; |
42e3fe0d ILT |
235 | // The string itself, a pointer into a Stringpool. |
236 | const Char_type* string; | |
730cdc88 ILT |
237 | // The length of the string in bytes, including the null terminator. |
238 | size_t length; | |
b8e6aad9 | 239 | |
42e3fe0d | 240 | Merged_string(Relobj *objecta, unsigned int shndxa, off_t offseta, |
730cdc88 ILT |
241 | const Char_type* stringa, size_t lengtha) |
242 | : object(objecta), shndx(shndxa), offset(offseta), string(stringa), | |
243 | length(lengtha) | |
b8e6aad9 ILT |
244 | { } |
245 | }; | |
246 | ||
42e3fe0d | 247 | typedef std::vector<Merged_string> Merged_strings; |
b8e6aad9 ILT |
248 | |
249 | // As we see the strings, we add them to a Stringpool. | |
250 | Stringpool_template<Char_type> stringpool_; | |
251 | // Map from a location in an input object to an entry in the | |
252 | // Stringpool. | |
42e3fe0d | 253 | Merged_strings merged_strings_; |
b8e6aad9 ILT |
254 | }; |
255 | ||
256 | } // End namespace gold. | |
257 | ||
258 | #endif // !defined(GOLD_MERGE_H) |