1 // reduced_debug_output.cc -- output reduced debugging information to save space
3 // Copyright (C) 2008-2019 Free Software Foundation, Inc.
4 // Written by Caleb Howe <cshowe@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.
25 #include "parameters.h"
28 #include "dwarf_reader.h"
29 #include "reduced_debug_output.h"
30 #include "int_encoding.h"
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.
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
)
51 uint64_t attribute
= read_unsigned_LEB_128(abbrev
, &LEB_size
);
53 elfcpp::DW_FORM form
=
54 static_cast<elfcpp::DW_FORM
>(read_unsigned_LEB_128(abbrev
,
57 if (!(attribute
|| form
))
59 if (die
>= buffer_end
)
63 case elfcpp::DW_FORM_flag_present
:
65 case elfcpp::DW_FORM_strp
:
66 case elfcpp::DW_FORM_sec_offset
:
69 case elfcpp::DW_FORM_addr
:
70 case elfcpp::DW_FORM_ref_addr
:
73 case elfcpp::DW_FORM_block1
:
77 case elfcpp::DW_FORM_block2
:
80 block_size
= read_from_pointer
<16>(&die
);
84 case elfcpp::DW_FORM_block4
:
87 block_size
= read_from_pointer
<32>(&die
);
91 case elfcpp::DW_FORM_block
:
92 case elfcpp::DW_FORM_exprloc
:
93 LEB_decoded
= read_unsigned_LEB_128(die
, &LEB_size
);
94 die
+= (LEB_decoded
+ LEB_size
);
96 case elfcpp::DW_FORM_data1
:
97 case elfcpp::DW_FORM_ref1
:
98 case elfcpp::DW_FORM_flag
:
101 case elfcpp::DW_FORM_data2
:
102 case elfcpp::DW_FORM_ref2
:
105 case elfcpp::DW_FORM_data4
:
106 case elfcpp::DW_FORM_ref4
:
109 case elfcpp::DW_FORM_data8
:
110 case elfcpp::DW_FORM_ref8
:
111 case elfcpp::DW_FORM_ref_sig8
:
114 case elfcpp::DW_FORM_ref_udata
:
115 case elfcpp::DW_FORM_udata
:
116 read_unsigned_LEB_128(die
, &LEB_size
);
119 case elfcpp::DW_FORM_sdata
:
120 read_signed_LEB_128(die
, &LEB_size
);
123 case elfcpp::DW_FORM_string
:
125 size_t length
= strlen(reinterpret_cast<char*>(die
));
129 case elfcpp::DW_FORM_indirect
:
130 case elfcpp::DW_FORM_GNU_addr_index
:
131 case elfcpp::DW_FORM_GNU_str_index
:
141 Output_reduced_debug_abbrev_section::set_final_data_size()
143 if (this->sized_
|| this->failed_
)
146 uint64_t abbrev_number
;
148 unsigned char* abbrev_data
= this->postprocessing_buffer();
149 unsigned char* abbrev_end
= this->postprocessing_buffer() +
150 this->postprocessing_buffer_size();
151 this->write_to_postprocessing_buffer();
152 while(abbrev_data
< abbrev_end
)
154 uint64_t abbrev_offset
= abbrev_data
- this->postprocessing_buffer();
155 while((abbrev_number
= read_unsigned_LEB_128(abbrev_data
, &LEB_size
)))
157 if (abbrev_data
>= abbrev_end
)
159 failed("Debug abbreviations extend beyond .debug_abbrev "
160 "section; failed to reduce debug abbreviations");
163 abbrev_data
+= LEB_size
;
165 // Together with the abbreviation number these fields make up
166 // the header for each abbreviation.
167 uint64_t abbrev_type
= read_unsigned_LEB_128(abbrev_data
, &LEB_size
);
168 abbrev_data
+= LEB_size
;
170 // This would ordinarily be the has_children field of the
171 // abbreviation. But it's going to be false after reducing the
172 // information, so there's no point in storing it.
175 // Read to the end of the current abbreviation.
176 // This is indicated by two zero unsigned LEBs in a row. We don't
177 // need to parse the data yet, so we just scan through the data
178 // looking for two consecutive 0 bytes indicating the end of the
180 unsigned char* current_abbrev
;
181 for (current_abbrev
= abbrev_data
;
182 current_abbrev
[0] || current_abbrev
[1];
185 if (current_abbrev
>= abbrev_end
)
187 this->failed(_("Debug abbreviations extend beyond "
188 ".debug_abbrev section; failed to reduce "
189 "debug abbreviations"));
193 // Account for the two nulls and advance to the start of the
194 // next abbreviation.
197 // We're eliminating every entry except for compile units, so we
198 // only need to store abbreviations that describe them
199 if (abbrev_type
== elfcpp::DW_TAG_compile_unit
)
201 write_unsigned_LEB_128(&this->data_
, ++this->abbrev_count_
);
202 write_unsigned_LEB_128(&this->data_
, abbrev_type
);
203 // has_children is false for all entries
204 this->data_
.push_back(0);
205 this->abbrev_mapping_
[std::make_pair(abbrev_offset
,
207 std::make_pair(abbrev_count_
, this->data_
.size());
208 this->data_
.insert(this->data_
.end(), abbrev_data
,
211 abbrev_data
= current_abbrev
;
213 gold_assert(LEB_size
== 1);
214 abbrev_data
+= LEB_size
;
216 // Null terminate the list of abbreviations
217 this->data_
.push_back(0);
218 this->set_data_size(data_
.size());
223 Output_reduced_debug_abbrev_section::do_write(Output_file
* of
)
225 off_t offset
= this->offset();
226 off_t data_size
= this->data_size();
227 unsigned char* view
= of
->get_output_view(offset
, data_size
);
229 memcpy(view
, this->postprocessing_buffer(),
230 this->postprocessing_buffer_size());
232 memcpy(view
, &this->data_
.front(), data_size
);
233 of
->write_output_view(offset
, data_size
, view
);
236 // Locates the abbreviation with abbreviation_number abbrev_number in the
237 // abbreviation table at offset abbrev_offset. abbrev_number is updated with
238 // its new abbreviation number and a pointer to the beginning of the
239 // abbreviation is returned.
241 Output_reduced_debug_abbrev_section::get_new_abbrev(
242 uint64_t* abbrev_number
, uint64_t abbrev_offset
)
244 set_final_data_size();
245 std::pair
<uint64_t, uint64_t> abbrev_info
=
246 this->abbrev_mapping_
[std::make_pair(abbrev_offset
, *abbrev_number
)];
247 *abbrev_number
= abbrev_info
.first
;
248 return &this->data_
[abbrev_info
.second
];
251 void Output_reduced_debug_info_section::set_final_data_size()
255 unsigned char* debug_info
= this->postprocessing_buffer();
256 unsigned char* debug_info_end
= (this->postprocessing_buffer()
257 + this->postprocessing_buffer_size());
258 unsigned char* next_compile_unit
;
259 this->write_to_postprocessing_buffer();
261 while (debug_info
< debug_info_end
)
263 uint32_t compile_unit_start
= read_from_pointer
<32>(&debug_info
);
264 // The first 4 bytes of each compile unit determine whether or
265 // not we're using dwarf32 or dwarf64. This is not necessarily
266 // related to whether the binary is 32 or 64 bits.
267 if (compile_unit_start
== 0xFFFFFFFF)
269 // Technically the size can be up to 96 bits. Rather than handle
270 // 96/128 bit integers we just truncate the size at 64 bits.
271 if (0 != read_from_pointer
<32>(&debug_info
))
273 this->failed(_("Extremely large compile unit in debug info; "
274 "failed to reduce debug info"));
277 const int dwarf64_header_size
= sizeof(uint64_t) + sizeof(uint16_t) +
278 sizeof(uint64_t) + sizeof(uint8_t);
279 if (debug_info
+ dwarf64_header_size
>= debug_info_end
)
281 this->failed(_("Debug info extends beyond .debug_info section;"
282 "failed to reduce debug info"));
286 uint64_t compile_unit_size
= read_from_pointer
<64>(&debug_info
);
287 next_compile_unit
= debug_info
+ compile_unit_size
;
288 uint16_t version
= read_from_pointer
<16>(&debug_info
);
289 uint64_t abbrev_offset
= read_from_pointer
<64>(&debug_info
);
290 uint8_t address_size
= read_from_pointer
<8>(&debug_info
);
292 uint64_t abbreviation_number
= read_unsigned_LEB_128(debug_info
,
294 debug_info
+= LEB_size
;
295 unsigned char* die_abbrev
= this->associated_abbrev_
->get_new_abbrev(
296 &abbreviation_number
, abbrev_offset
);
297 unsigned char* die_end
;
298 if (!this->get_die_end(debug_info
, die_abbrev
, &die_end
,
299 debug_info_end
, address_size
, true))
301 this->failed(_("Invalid DIE in debug info; "
302 "failed to reduce debug info"));
306 insert_into_vector
<32>(&this->data_
, 0xFFFFFFFF);
307 insert_into_vector
<32>(&this->data_
, 0);
308 insert_into_vector
<64>(
310 (11 + get_length_as_unsigned_LEB_128(abbreviation_number
)
311 + die_end
- debug_info
));
312 insert_into_vector
<16>(&this->data_
, version
);
313 insert_into_vector
<64>(&this->data_
, 0);
314 insert_into_vector
<8>(&this->data_
, address_size
);
315 write_unsigned_LEB_128(&this->data_
, abbreviation_number
);
316 this->data_
.insert(this->data_
.end(), debug_info
, die_end
);
320 const int dwarf32_header_size
=
321 sizeof(uint16_t) + sizeof(uint32_t) + sizeof(uint8_t);
322 if (debug_info
+ dwarf32_header_size
>= debug_info_end
)
324 this->failed(_("Debug info extends beyond .debug_info section; "
325 "failed to reduce debug info"));
328 uint32_t compile_unit_size
= compile_unit_start
;
329 next_compile_unit
= debug_info
+ compile_unit_size
;
330 uint16_t version
= read_from_pointer
<16>(&debug_info
);
331 uint32_t abbrev_offset
= read_from_pointer
<32>(&debug_info
);
332 uint8_t address_size
= read_from_pointer
<8>(&debug_info
);
334 uint64_t abbreviation_number
= read_unsigned_LEB_128(debug_info
,
336 debug_info
+= LEB_size
;
337 unsigned char* die_abbrev
= this->associated_abbrev_
->get_new_abbrev(
338 &abbreviation_number
, abbrev_offset
);
339 unsigned char* die_end
;
340 if (!this->get_die_end(debug_info
, die_abbrev
, &die_end
,
341 debug_info_end
, address_size
, false))
343 this->failed(_("Invalid DIE in debug info; "
344 "failed to reduce debug info"));
348 insert_into_vector
<32>(
350 (7 + get_length_as_unsigned_LEB_128(abbreviation_number
)
351 + die_end
- debug_info
));
352 insert_into_vector
<16>(&this->data_
, version
);
353 insert_into_vector
<32>(&this->data_
, 0);
354 insert_into_vector
<8>(&this->data_
, address_size
);
355 write_unsigned_LEB_128(&this->data_
, abbreviation_number
);
356 this->data_
.insert(this->data_
.end(), debug_info
, die_end
);
358 debug_info
= next_compile_unit
;
360 this->set_data_size(data_
.size());
363 void Output_reduced_debug_info_section::do_write(Output_file
* of
)
365 off_t offset
= this->offset();
366 off_t data_size
= this->data_size();
367 unsigned char* view
= of
->get_output_view(offset
, data_size
);
369 memcpy(view
, this->postprocessing_buffer(),
370 this->postprocessing_buffer_size());
372 memcpy(view
, &this->data_
.front(), data_size
);
373 of
->write_output_view(offset
, data_size
, view
);
376 } // End namespace gold.
This page took 0.037841 seconds and 4 git commands to generate.