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1 | // reduced_debug_output.cc -- output reduced debugging information to save space |
2 | ||
2ea97941 | 3 | // Copyright 2008 Free Software Foundation, Inc. |
62b01cb5 ILT |
4 | // Written by Caleb Howe <cshowe@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 | #include "gold.h" | |
24 | ||
25 | #include "parameters.h" | |
26 | #include "options.h" | |
27 | #include "dwarf.h" | |
28 | #include "dwarf_reader.h" | |
29 | #include "reduced_debug_output.h" | |
4f787271 | 30 | #include "int_encoding.h" |
62b01cb5 ILT |
31 | |
32 | #include <vector> | |
33 | ||
34 | namespace gold | |
35 | { | |
36 | ||
62b01cb5 ILT |
37 | // Given a pointer to the beginning of a die and the beginning of the associated |
38 | // abbreviation fills in die_end with the end of the information entry. If | |
39 | // successful returns true. Get_die_end also takes a pointer to the end of the | |
40 | // buffer containing the die. If die_end would be beyond the end of the | |
41 | // buffer, or if an unsupported dwarf form is encountered returns false. | |
42 | bool | |
43 | Output_reduced_debug_info_section::get_die_end( | |
44 | unsigned char* die, unsigned char* abbrev, unsigned char** die_end, | |
45 | unsigned char* buffer_end, int address_size, bool is64) | |
46 | { | |
47 | size_t LEB_size; | |
48 | uint64_t LEB_decoded; | |
49 | for(;;) | |
50 | { | |
51 | uint64_t attribute = read_unsigned_LEB_128(abbrev, &LEB_size); | |
52 | abbrev += LEB_size; | |
53 | elfcpp::DW_FORM form = | |
54 | static_cast<elfcpp::DW_FORM>(read_unsigned_LEB_128(abbrev, | |
55 | &LEB_size)); | |
56 | abbrev += LEB_size; | |
57 | if (!(attribute || form)) | |
58 | break; | |
59 | if (die >= buffer_end) | |
60 | return false; | |
61 | switch(form) | |
62 | { | |
63 | case elfcpp::DW_FORM_null: | |
64 | break; | |
65 | case elfcpp::DW_FORM_strp: | |
66 | die += is64 ? 8 : 4; | |
67 | break; | |
68 | case elfcpp::DW_FORM_addr: | |
69 | case elfcpp::DW_FORM_ref_addr: | |
70 | die += address_size; | |
71 | break; | |
72 | case elfcpp::DW_FORM_block1: | |
73 | die += *die; | |
74 | die += 1; | |
75 | break; | |
76 | case elfcpp::DW_FORM_block2: | |
77 | { | |
78 | uint16_t block_size; | |
79 | block_size = read_from_pointer<16>(&die); | |
80 | die += block_size; | |
81 | break; | |
82 | } | |
83 | case elfcpp::DW_FORM_block4: | |
84 | { | |
85 | uint32_t block_size; | |
86 | block_size = read_from_pointer<32>(&die); | |
87 | die += block_size; | |
88 | break; | |
89 | } | |
90 | case elfcpp::DW_FORM_block: | |
91 | LEB_decoded = read_unsigned_LEB_128(die, &LEB_size); | |
92 | die += (LEB_decoded + LEB_size); | |
93 | break; | |
94 | case elfcpp::DW_FORM_data1: | |
95 | case elfcpp::DW_FORM_ref1: | |
96 | case elfcpp::DW_FORM_flag: | |
97 | die += 1; | |
98 | break; | |
99 | case elfcpp::DW_FORM_data2: | |
100 | case elfcpp::DW_FORM_ref2: | |
101 | die += 2; | |
102 | break; | |
103 | case elfcpp::DW_FORM_data4: | |
104 | case elfcpp::DW_FORM_ref4: | |
105 | die += 4; | |
106 | break; | |
107 | case elfcpp::DW_FORM_data8: | |
108 | case elfcpp::DW_FORM_ref8: | |
109 | die += 8; | |
110 | break; | |
111 | case elfcpp::DW_FORM_ref_udata: | |
112 | case elfcpp::DW_FORM_udata: | |
113 | read_unsigned_LEB_128(die, &LEB_size); | |
114 | die += LEB_size; | |
115 | break; | |
116 | case elfcpp::DW_FORM_string: | |
117 | { | |
118 | size_t length = strlen(reinterpret_cast<char*>(die)); | |
119 | die += length + 1; | |
120 | break; | |
121 | } | |
122 | case elfcpp::DW_FORM_sdata: | |
123 | case elfcpp::DW_FORM_indirect: | |
124 | return false; | |
125 | } | |
126 | } | |
127 | *die_end = die; | |
128 | return true; | |
129 | } | |
130 | ||
131 | void | |
132 | Output_reduced_debug_abbrev_section::set_final_data_size() | |
133 | { | |
134 | if (this->sized_ || this->failed_) | |
135 | return; | |
136 | ||
137 | uint64_t abbrev_number; | |
138 | size_t LEB_size; | |
139 | unsigned char* abbrev_data = this->postprocessing_buffer(); | |
140 | unsigned char* abbrev_end = this->postprocessing_buffer() + | |
141 | this->postprocessing_buffer_size(); | |
142 | this->write_to_postprocessing_buffer(); | |
143 | while(abbrev_data < abbrev_end) | |
144 | { | |
145 | uint64_t abbrev_offset = abbrev_data - this->postprocessing_buffer(); | |
146 | while((abbrev_number = read_unsigned_LEB_128(abbrev_data, &LEB_size))) | |
147 | { | |
148 | if (abbrev_data >= abbrev_end) | |
149 | { | |
150 | failed("Debug abbreviations extend beyond .debug_abbrev " | |
151 | "section; failed to reduce debug abbreviations"); | |
152 | return; | |
153 | } | |
154 | abbrev_data += LEB_size; | |
155 | ||
156 | // Together with the abbreviation number these fields make up | |
157 | // the header for each abbreviation | |
158 | uint64_t abbrev_type = read_unsigned_LEB_128(abbrev_data, &LEB_size); | |
159 | abbrev_data += LEB_size; | |
160 | ||
161 | // This would ordinarily be the has_children field of the | |
162 | // abbreviation. But it's going to be false after reducting the | |
163 | // information, so there's no point in storing it | |
164 | abbrev_data++; | |
165 | ||
166 | // Read to the end of the current abbreviation | |
167 | // This is indicated by two zero unsigned LEBs in a row. We don't | |
168 | // need to parse the data yet, so we just scan through the data | |
169 | // looking for two consecutive 0 bytes indicating the end of the | |
170 | // abbreviation | |
171 | unsigned char* current_abbrev; | |
172 | for (current_abbrev = abbrev_data; | |
173 | current_abbrev[0] || current_abbrev[1]; | |
174 | current_abbrev++) | |
175 | { | |
176 | if (current_abbrev >= abbrev_end) | |
177 | { | |
178 | this->failed(_("Debug abbreviations extend beyond " | |
179 | ".debug_abbrev section; failed to reduce " | |
180 | "debug abbreviations")); | |
181 | return; | |
182 | } | |
183 | } | |
184 | // Account for the two nulls and advance to the start of the | |
185 | // next abbreviation. | |
186 | current_abbrev += 2; | |
187 | ||
188 | // We're eliminating every entry except for compile units, so we | |
189 | // only need to store abbreviations that describe them | |
190 | if (abbrev_type == elfcpp::DW_TAG_compile_unit) | |
191 | { | |
192 | write_unsigned_LEB_128(&this->data_, ++this->abbrev_count_); | |
193 | write_unsigned_LEB_128(&this->data_, abbrev_type); | |
194 | // has_children is false for all entries | |
195 | this->data_.push_back(0); | |
196 | this->abbrev_mapping_[std::make_pair(abbrev_offset, | |
197 | abbrev_number)] = | |
198 | std::make_pair(abbrev_count_, this->data_.size()); | |
199 | this->data_.insert(this->data_.end(), abbrev_data, | |
200 | current_abbrev); | |
201 | } | |
202 | abbrev_data = current_abbrev; | |
203 | } | |
204 | gold_assert(LEB_size == 1); | |
205 | abbrev_data += LEB_size; | |
206 | } | |
207 | // Null terminate the list of abbreviations | |
208 | this->data_.push_back(0); | |
209 | this->set_data_size(data_.size()); | |
210 | this->sized_ = true; | |
211 | } | |
212 | ||
213 | void | |
214 | Output_reduced_debug_abbrev_section::do_write(Output_file* of) | |
215 | { | |
2ea97941 ILT |
216 | off_t offset = this->offset(); |
217 | off_t data_size = this->data_size(); | |
218 | unsigned char* view = of->get_output_view(offset, data_size); | |
62b01cb5 ILT |
219 | if (this->failed_) |
220 | memcpy(view, this->postprocessing_buffer(), | |
221 | this->postprocessing_buffer_size()); | |
222 | else | |
2ea97941 ILT |
223 | memcpy(view, &this->data_.front(), data_size); |
224 | of->write_output_view(offset, data_size, view); | |
62b01cb5 ILT |
225 | } |
226 | ||
227 | // Locates the abbreviation with abbreviation_number abbrev_number in the | |
228 | // abbreviation table at offset abbrev_offset. abbrev_number is updated with | |
229 | // its new abbreviation number and a pointer to the beginning of the | |
230 | // abbreviation is returned. | |
231 | unsigned char* | |
232 | Output_reduced_debug_abbrev_section::get_new_abbrev( | |
233 | uint64_t* abbrev_number, uint64_t abbrev_offset) | |
234 | { | |
235 | set_final_data_size(); | |
236 | std::pair<uint64_t, uint64_t> abbrev_info = | |
237 | this->abbrev_mapping_[std::make_pair(abbrev_offset, *abbrev_number)]; | |
238 | *abbrev_number = abbrev_info.first; | |
239 | return &this->data_[abbrev_info.second]; | |
240 | } | |
241 | ||
242 | void Output_reduced_debug_info_section::set_final_data_size() | |
243 | { | |
244 | if (this->failed_) | |
245 | return; | |
246 | unsigned char* debug_info = this->postprocessing_buffer(); | |
247 | unsigned char* debug_info_end = (this->postprocessing_buffer() | |
248 | + this->postprocessing_buffer_size()); | |
249 | unsigned char* next_compile_unit; | |
250 | this->write_to_postprocessing_buffer(); | |
251 | ||
252 | while (debug_info < debug_info_end) | |
253 | { | |
254 | uint32_t compile_unit_start = read_from_pointer<32>(&debug_info); | |
255 | // The first 4 bytes of each compile unit determine whether or | |
256 | // not we're using dwarf32 or dwarf64. This is not necessarily | |
257 | // related to whether the binary is 32 or 64 bits. | |
258 | if (compile_unit_start == 0xFFFFFFFF) | |
259 | { | |
260 | // Technically the size can be up to 96 bits. Rather than handle | |
261 | // 96/128 bit integers we just truncate the size at 64 bits. | |
262 | if (0 != read_from_pointer<32>(&debug_info)) | |
263 | { | |
264 | this->failed(_("Extremely large compile unit in debug info; " | |
265 | "failed to reduce debug info")); | |
266 | return; | |
267 | } | |
268 | const int dwarf64_header_size = sizeof(uint64_t) + sizeof(uint16_t) + | |
269 | sizeof(uint64_t) + sizeof(uint8_t); | |
270 | if (debug_info + dwarf64_header_size >= debug_info_end) | |
271 | { | |
272 | this->failed(_("Debug info extends beyond .debug_info section;" | |
273 | "failed to reduce debug info")); | |
274 | return; | |
275 | } | |
276 | ||
277 | uint64_t compile_unit_size = read_from_pointer<64>(&debug_info); | |
278 | next_compile_unit = debug_info + compile_unit_size; | |
279 | uint16_t version = read_from_pointer<16>(&debug_info); | |
280 | uint64_t abbrev_offset = read_from_pointer<64>(&debug_info); | |
281 | uint8_t address_size = read_from_pointer<8>(&debug_info); | |
282 | size_t LEB_size; | |
283 | uint64_t abbreviation_number = read_unsigned_LEB_128(debug_info, | |
284 | &LEB_size); | |
285 | debug_info += LEB_size; | |
286 | unsigned char* die_abbrev = this->associated_abbrev_->get_new_abbrev( | |
287 | &abbreviation_number, abbrev_offset); | |
288 | unsigned char* die_end; | |
289 | if (!this->get_die_end(debug_info, die_abbrev, &die_end, | |
290 | debug_info_end, address_size, true)) | |
291 | { | |
292 | this->failed(_("Invalid DIE in debug info; " | |
293 | "failed to reduce debug info")); | |
294 | return; | |
295 | } | |
296 | ||
e0ebcf42 ILT |
297 | insert_into_vector<32>(&this->data_, 0xFFFFFFFF); |
298 | insert_into_vector<32>(&this->data_, 0); | |
299 | insert_into_vector<64>( | |
62b01cb5 ILT |
300 | &this->data_, |
301 | (11 + get_length_as_unsigned_LEB_128(abbreviation_number) | |
302 | + die_end - debug_info)); | |
e0ebcf42 ILT |
303 | insert_into_vector<16>(&this->data_, version); |
304 | insert_into_vector<64>(&this->data_, 0); | |
305 | insert_into_vector<8>(&this->data_, address_size); | |
62b01cb5 ILT |
306 | write_unsigned_LEB_128(&this->data_, abbreviation_number); |
307 | this->data_.insert(this->data_.end(), debug_info, die_end); | |
308 | } | |
309 | else | |
310 | { | |
311 | const int dwarf32_header_size = | |
312 | sizeof(uint16_t) + sizeof(uint32_t) + sizeof(uint8_t); | |
313 | if (debug_info + dwarf32_header_size >= debug_info_end) | |
314 | { | |
315 | this->failed(_("Debug info extends beyond .debug_info section; " | |
316 | "failed to reduce debug info")); | |
317 | return; | |
318 | } | |
319 | uint32_t compile_unit_size = compile_unit_start; | |
320 | next_compile_unit = debug_info + compile_unit_size; | |
321 | uint16_t version = read_from_pointer<16>(&debug_info); | |
322 | uint32_t abbrev_offset = read_from_pointer<32>(&debug_info); | |
323 | uint8_t address_size = read_from_pointer<8>(&debug_info); | |
324 | size_t LEB_size; | |
325 | uint64_t abbreviation_number = read_unsigned_LEB_128(debug_info, | |
326 | &LEB_size); | |
327 | debug_info += LEB_size; | |
328 | unsigned char* die_abbrev = this->associated_abbrev_->get_new_abbrev( | |
329 | &abbreviation_number, abbrev_offset); | |
330 | unsigned char* die_end; | |
331 | if (!this->get_die_end(debug_info, die_abbrev, &die_end, | |
332 | debug_info_end, address_size, false)) | |
333 | { | |
334 | this->failed(_("Invalid DIE in debug info; " | |
335 | "failed to reduce debug info")); | |
336 | return; | |
337 | } | |
338 | ||
e0ebcf42 | 339 | insert_into_vector<32>( |
62b01cb5 ILT |
340 | &this->data_, |
341 | (7 + get_length_as_unsigned_LEB_128(abbreviation_number) | |
342 | + die_end - debug_info)); | |
e0ebcf42 ILT |
343 | insert_into_vector<16>(&this->data_, version); |
344 | insert_into_vector<32>(&this->data_, 0); | |
345 | insert_into_vector<8>(&this->data_, address_size); | |
62b01cb5 ILT |
346 | write_unsigned_LEB_128(&this->data_, abbreviation_number); |
347 | this->data_.insert(this->data_.end(), debug_info, die_end); | |
348 | } | |
349 | debug_info = next_compile_unit; | |
350 | } | |
351 | this->set_data_size(data_.size()); | |
352 | } | |
353 | ||
354 | void Output_reduced_debug_info_section::do_write(Output_file* of) | |
355 | { | |
2ea97941 ILT |
356 | off_t offset = this->offset(); |
357 | off_t data_size = this->data_size(); | |
358 | unsigned char* view = of->get_output_view(offset, data_size); | |
62b01cb5 ILT |
359 | if (this->failed_) |
360 | memcpy(view, this->postprocessing_buffer(), | |
361 | this->postprocessing_buffer_size()); | |
362 | else | |
2ea97941 ILT |
363 | memcpy(view, &this->data_.front(), data_size); |
364 | of->write_output_view(offset, data_size, view); | |
62b01cb5 ILT |
365 | } |
366 | ||
367 | } // End namespace gold. |