1 // reduced_debug_output.cc -- output reduced debugging information to save space
3 // Copyright 2008 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"
37 write_unsigned_LEB_128(std::vector
<unsigned char>* buffer
, uint64_t value
)
41 unsigned char current_byte
= value
& 0x7f;
47 buffer
->push_back(current_byte
);
53 get_length_as_unsigned_LEB_128(uint64_t value
)
58 unsigned char current_byte
= value
& 0x7f;
70 template <int valsize
>
71 void insert_into_vector(std::vector
<unsigned char>* destination
,
72 typename
elfcpp::Valtype_base
<valsize
>::Valtype value
)
74 unsigned char buffer
[valsize
/ 8];
75 if (parameters
->target().is_big_endian())
76 elfcpp::Swap_unaligned
<valsize
, true>::writeval(buffer
, value
);
78 elfcpp::Swap_unaligned
<valsize
, false>::writeval(buffer
, value
);
79 destination
->insert(destination
->end(), buffer
, buffer
+ valsize
/ 8);
82 template <int valsize
>
83 typename
elfcpp::Valtype_base
<valsize
>::Valtype
84 read_from_pointer(unsigned char** source
)
86 typename
elfcpp::Valtype_base
<valsize
>::Valtype return_value
;
87 if (parameters
->target().is_big_endian())
88 return_value
= elfcpp::Swap_unaligned
<valsize
, true>::readval(*source
);
90 return_value
= elfcpp::Swap_unaligned
<valsize
, false>::readval(*source
);
91 *source
+= valsize
/ 8;
95 // Given a pointer to the beginning of a die and the beginning of the associated
96 // abbreviation fills in die_end with the end of the information entry. If
97 // successful returns true. Get_die_end also takes a pointer to the end of the
98 // buffer containing the die. If die_end would be beyond the end of the
99 // buffer, or if an unsupported dwarf form is encountered returns false.
101 Output_reduced_debug_info_section::get_die_end(
102 unsigned char* die
, unsigned char* abbrev
, unsigned char** die_end
,
103 unsigned char* buffer_end
, int address_size
, bool is64
)
106 uint64_t LEB_decoded
;
109 uint64_t attribute
= read_unsigned_LEB_128(abbrev
, &LEB_size
);
111 elfcpp::DW_FORM form
=
112 static_cast<elfcpp::DW_FORM
>(read_unsigned_LEB_128(abbrev
,
115 if (!(attribute
|| form
))
117 if (die
>= buffer_end
)
121 case elfcpp::DW_FORM_null
:
123 case elfcpp::DW_FORM_strp
:
126 case elfcpp::DW_FORM_addr
:
127 case elfcpp::DW_FORM_ref_addr
:
130 case elfcpp::DW_FORM_block1
:
134 case elfcpp::DW_FORM_block2
:
137 block_size
= read_from_pointer
<16>(&die
);
141 case elfcpp::DW_FORM_block4
:
144 block_size
= read_from_pointer
<32>(&die
);
148 case elfcpp::DW_FORM_block
:
149 LEB_decoded
= read_unsigned_LEB_128(die
, &LEB_size
);
150 die
+= (LEB_decoded
+ LEB_size
);
152 case elfcpp::DW_FORM_data1
:
153 case elfcpp::DW_FORM_ref1
:
154 case elfcpp::DW_FORM_flag
:
157 case elfcpp::DW_FORM_data2
:
158 case elfcpp::DW_FORM_ref2
:
161 case elfcpp::DW_FORM_data4
:
162 case elfcpp::DW_FORM_ref4
:
165 case elfcpp::DW_FORM_data8
:
166 case elfcpp::DW_FORM_ref8
:
169 case elfcpp::DW_FORM_ref_udata
:
170 case elfcpp::DW_FORM_udata
:
171 read_unsigned_LEB_128(die
, &LEB_size
);
174 case elfcpp::DW_FORM_string
:
176 size_t length
= strlen(reinterpret_cast<char*>(die
));
180 case elfcpp::DW_FORM_sdata
:
181 case elfcpp::DW_FORM_indirect
:
190 Output_reduced_debug_abbrev_section::set_final_data_size()
192 if (this->sized_
|| this->failed_
)
195 uint64_t abbrev_number
;
197 unsigned char* abbrev_data
= this->postprocessing_buffer();
198 unsigned char* abbrev_end
= this->postprocessing_buffer() +
199 this->postprocessing_buffer_size();
200 this->write_to_postprocessing_buffer();
201 while(abbrev_data
< abbrev_end
)
203 uint64_t abbrev_offset
= abbrev_data
- this->postprocessing_buffer();
204 while((abbrev_number
= read_unsigned_LEB_128(abbrev_data
, &LEB_size
)))
206 if (abbrev_data
>= abbrev_end
)
208 failed("Debug abbreviations extend beyond .debug_abbrev "
209 "section; failed to reduce debug abbreviations");
212 abbrev_data
+= LEB_size
;
214 // Together with the abbreviation number these fields make up
215 // the header for each abbreviation
216 uint64_t abbrev_type
= read_unsigned_LEB_128(abbrev_data
, &LEB_size
);
217 abbrev_data
+= LEB_size
;
219 // This would ordinarily be the has_children field of the
220 // abbreviation. But it's going to be false after reducting the
221 // information, so there's no point in storing it
224 // Read to the end of the current abbreviation
225 // This is indicated by two zero unsigned LEBs in a row. We don't
226 // need to parse the data yet, so we just scan through the data
227 // looking for two consecutive 0 bytes indicating the end of the
229 unsigned char* current_abbrev
;
230 for (current_abbrev
= abbrev_data
;
231 current_abbrev
[0] || current_abbrev
[1];
234 if (current_abbrev
>= abbrev_end
)
236 this->failed(_("Debug abbreviations extend beyond "
237 ".debug_abbrev section; failed to reduce "
238 "debug abbreviations"));
242 // Account for the two nulls and advance to the start of the
243 // next abbreviation.
246 // We're eliminating every entry except for compile units, so we
247 // only need to store abbreviations that describe them
248 if (abbrev_type
== elfcpp::DW_TAG_compile_unit
)
250 write_unsigned_LEB_128(&this->data_
, ++this->abbrev_count_
);
251 write_unsigned_LEB_128(&this->data_
, abbrev_type
);
252 // has_children is false for all entries
253 this->data_
.push_back(0);
254 this->abbrev_mapping_
[std::make_pair(abbrev_offset
,
256 std::make_pair(abbrev_count_
, this->data_
.size());
257 this->data_
.insert(this->data_
.end(), abbrev_data
,
260 abbrev_data
= current_abbrev
;
262 gold_assert(LEB_size
== 1);
263 abbrev_data
+= LEB_size
;
265 // Null terminate the list of abbreviations
266 this->data_
.push_back(0);
267 this->set_data_size(data_
.size());
272 Output_reduced_debug_abbrev_section::do_write(Output_file
* of
)
274 off_t offset
= this->offset();
275 off_t data_size
= this->data_size();
276 unsigned char* view
= of
->get_output_view(offset
, data_size
);
278 memcpy(view
, this->postprocessing_buffer(),
279 this->postprocessing_buffer_size());
281 memcpy(view
, &this->data_
.front(), data_size
);
282 of
->write_output_view(offset
, data_size
, view
);
285 // Locates the abbreviation with abbreviation_number abbrev_number in the
286 // abbreviation table at offset abbrev_offset. abbrev_number is updated with
287 // its new abbreviation number and a pointer to the beginning of the
288 // abbreviation is returned.
290 Output_reduced_debug_abbrev_section::get_new_abbrev(
291 uint64_t* abbrev_number
, uint64_t abbrev_offset
)
293 set_final_data_size();
294 std::pair
<uint64_t, uint64_t> abbrev_info
=
295 this->abbrev_mapping_
[std::make_pair(abbrev_offset
, *abbrev_number
)];
296 *abbrev_number
= abbrev_info
.first
;
297 return &this->data_
[abbrev_info
.second
];
300 void Output_reduced_debug_info_section::set_final_data_size()
304 unsigned char* debug_info
= this->postprocessing_buffer();
305 unsigned char* debug_info_end
= (this->postprocessing_buffer()
306 + this->postprocessing_buffer_size());
307 unsigned char* next_compile_unit
;
308 this->write_to_postprocessing_buffer();
310 while (debug_info
< debug_info_end
)
312 uint32_t compile_unit_start
= read_from_pointer
<32>(&debug_info
);
313 // The first 4 bytes of each compile unit determine whether or
314 // not we're using dwarf32 or dwarf64. This is not necessarily
315 // related to whether the binary is 32 or 64 bits.
316 if (compile_unit_start
== 0xFFFFFFFF)
318 // Technically the size can be up to 96 bits. Rather than handle
319 // 96/128 bit integers we just truncate the size at 64 bits.
320 if (0 != read_from_pointer
<32>(&debug_info
))
322 this->failed(_("Extremely large compile unit in debug info; "
323 "failed to reduce debug info"));
326 const int dwarf64_header_size
= sizeof(uint64_t) + sizeof(uint16_t) +
327 sizeof(uint64_t) + sizeof(uint8_t);
328 if (debug_info
+ dwarf64_header_size
>= debug_info_end
)
330 this->failed(_("Debug info extends beyond .debug_info section;"
331 "failed to reduce debug info"));
335 uint64_t compile_unit_size
= read_from_pointer
<64>(&debug_info
);
336 next_compile_unit
= debug_info
+ compile_unit_size
;
337 uint16_t version
= read_from_pointer
<16>(&debug_info
);
338 uint64_t abbrev_offset
= read_from_pointer
<64>(&debug_info
);
339 uint8_t address_size
= read_from_pointer
<8>(&debug_info
);
341 uint64_t abbreviation_number
= read_unsigned_LEB_128(debug_info
,
343 debug_info
+= LEB_size
;
344 unsigned char* die_abbrev
= this->associated_abbrev_
->get_new_abbrev(
345 &abbreviation_number
, abbrev_offset
);
346 unsigned char* die_end
;
347 if (!this->get_die_end(debug_info
, die_abbrev
, &die_end
,
348 debug_info_end
, address_size
, true))
350 this->failed(_("Invalid DIE in debug info; "
351 "failed to reduce debug info"));
355 insert_into_vector
<32>(&this->data_
, 0xFFFFFFFF);
356 insert_into_vector
<32>(&this->data_
, 0);
357 insert_into_vector
<64>(
359 (11 + get_length_as_unsigned_LEB_128(abbreviation_number
)
360 + die_end
- debug_info
));
361 insert_into_vector
<16>(&this->data_
, version
);
362 insert_into_vector
<64>(&this->data_
, 0);
363 insert_into_vector
<8>(&this->data_
, address_size
);
364 write_unsigned_LEB_128(&this->data_
, abbreviation_number
);
365 this->data_
.insert(this->data_
.end(), debug_info
, die_end
);
369 const int dwarf32_header_size
=
370 sizeof(uint16_t) + sizeof(uint32_t) + sizeof(uint8_t);
371 if (debug_info
+ dwarf32_header_size
>= debug_info_end
)
373 this->failed(_("Debug info extends beyond .debug_info section; "
374 "failed to reduce debug info"));
377 uint32_t compile_unit_size
= compile_unit_start
;
378 next_compile_unit
= debug_info
+ compile_unit_size
;
379 uint16_t version
= read_from_pointer
<16>(&debug_info
);
380 uint32_t abbrev_offset
= read_from_pointer
<32>(&debug_info
);
381 uint8_t address_size
= read_from_pointer
<8>(&debug_info
);
383 uint64_t abbreviation_number
= read_unsigned_LEB_128(debug_info
,
385 debug_info
+= LEB_size
;
386 unsigned char* die_abbrev
= this->associated_abbrev_
->get_new_abbrev(
387 &abbreviation_number
, abbrev_offset
);
388 unsigned char* die_end
;
389 if (!this->get_die_end(debug_info
, die_abbrev
, &die_end
,
390 debug_info_end
, address_size
, false))
392 this->failed(_("Invalid DIE in debug info; "
393 "failed to reduce debug info"));
397 insert_into_vector
<32>(
399 (7 + get_length_as_unsigned_LEB_128(abbreviation_number
)
400 + die_end
- debug_info
));
401 insert_into_vector
<16>(&this->data_
, version
);
402 insert_into_vector
<32>(&this->data_
, 0);
403 insert_into_vector
<8>(&this->data_
, address_size
);
404 write_unsigned_LEB_128(&this->data_
, abbreviation_number
);
405 this->data_
.insert(this->data_
.end(), debug_info
, die_end
);
407 debug_info
= next_compile_unit
;
409 this->set_data_size(data_
.size());
412 void Output_reduced_debug_info_section::do_write(Output_file
* of
)
414 off_t offset
= this->offset();
415 off_t data_size
= this->data_size();
416 unsigned char* view
= of
->get_output_view(offset
, data_size
);
418 memcpy(view
, this->postprocessing_buffer(),
419 this->postprocessing_buffer_size());
421 memcpy(view
, &this->data_
.front(), data_size
);
422 of
->write_output_view(offset
, data_size
, view
);
425 } // End namespace gold.
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