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
)
76 unsigned char buffer
[valsize
/ 8];
79 if (parameters
->target().is_big_endian())
80 elfcpp::Swap
<valsize
, true>::writeval(u
.buffer
, value
);
82 elfcpp::Swap
<valsize
, false>::writeval(u
.buffer
, value
);
83 destination
->insert(destination
->end(), u
.buffer
, u
.buffer
+ valsize
/ 8);
86 template <int valsize
>
87 typename
elfcpp::Valtype_base
<valsize
>::Valtype
88 read_from_pointer(unsigned char** source
)
90 typename
elfcpp::Valtype_base
<valsize
>::Valtype return_value
;
91 if (parameters
->target().is_big_endian())
92 return_value
= elfcpp::Swap_unaligned
<valsize
, true>::readval(*source
);
94 return_value
= elfcpp::Swap_unaligned
<valsize
, false>::readval(*source
);
95 *source
+= valsize
/ 8;
99 // Given a pointer to the beginning of a die and the beginning of the associated
100 // abbreviation fills in die_end with the end of the information entry. If
101 // successful returns true. Get_die_end also takes a pointer to the end of the
102 // buffer containing the die. If die_end would be beyond the end of the
103 // buffer, or if an unsupported dwarf form is encountered returns false.
105 Output_reduced_debug_info_section::get_die_end(
106 unsigned char* die
, unsigned char* abbrev
, unsigned char** die_end
,
107 unsigned char* buffer_end
, int address_size
, bool is64
)
110 uint64_t LEB_decoded
;
113 uint64_t attribute
= read_unsigned_LEB_128(abbrev
, &LEB_size
);
115 elfcpp::DW_FORM form
=
116 static_cast<elfcpp::DW_FORM
>(read_unsigned_LEB_128(abbrev
,
119 if (!(attribute
|| form
))
121 if (die
>= buffer_end
)
125 case elfcpp::DW_FORM_null
:
127 case elfcpp::DW_FORM_strp
:
130 case elfcpp::DW_FORM_addr
:
131 case elfcpp::DW_FORM_ref_addr
:
134 case elfcpp::DW_FORM_block1
:
138 case elfcpp::DW_FORM_block2
:
141 block_size
= read_from_pointer
<16>(&die
);
145 case elfcpp::DW_FORM_block4
:
148 block_size
= read_from_pointer
<32>(&die
);
152 case elfcpp::DW_FORM_block
:
153 LEB_decoded
= read_unsigned_LEB_128(die
, &LEB_size
);
154 die
+= (LEB_decoded
+ LEB_size
);
156 case elfcpp::DW_FORM_data1
:
157 case elfcpp::DW_FORM_ref1
:
158 case elfcpp::DW_FORM_flag
:
161 case elfcpp::DW_FORM_data2
:
162 case elfcpp::DW_FORM_ref2
:
165 case elfcpp::DW_FORM_data4
:
166 case elfcpp::DW_FORM_ref4
:
169 case elfcpp::DW_FORM_data8
:
170 case elfcpp::DW_FORM_ref8
:
173 case elfcpp::DW_FORM_ref_udata
:
174 case elfcpp::DW_FORM_udata
:
175 read_unsigned_LEB_128(die
, &LEB_size
);
178 case elfcpp::DW_FORM_string
:
180 size_t length
= strlen(reinterpret_cast<char*>(die
));
184 case elfcpp::DW_FORM_sdata
:
185 case elfcpp::DW_FORM_indirect
:
194 Output_reduced_debug_abbrev_section::set_final_data_size()
196 if (this->sized_
|| this->failed_
)
199 uint64_t abbrev_number
;
201 unsigned char* abbrev_data
= this->postprocessing_buffer();
202 unsigned char* abbrev_end
= this->postprocessing_buffer() +
203 this->postprocessing_buffer_size();
204 this->write_to_postprocessing_buffer();
205 while(abbrev_data
< abbrev_end
)
207 uint64_t abbrev_offset
= abbrev_data
- this->postprocessing_buffer();
208 while((abbrev_number
= read_unsigned_LEB_128(abbrev_data
, &LEB_size
)))
210 if (abbrev_data
>= abbrev_end
)
212 failed("Debug abbreviations extend beyond .debug_abbrev "
213 "section; failed to reduce debug abbreviations");
216 abbrev_data
+= LEB_size
;
218 // Together with the abbreviation number these fields make up
219 // the header for each abbreviation
220 uint64_t abbrev_type
= read_unsigned_LEB_128(abbrev_data
, &LEB_size
);
221 abbrev_data
+= LEB_size
;
223 // This would ordinarily be the has_children field of the
224 // abbreviation. But it's going to be false after reducting the
225 // information, so there's no point in storing it
228 // Read to the end of the current abbreviation
229 // This is indicated by two zero unsigned LEBs in a row. We don't
230 // need to parse the data yet, so we just scan through the data
231 // looking for two consecutive 0 bytes indicating the end of the
233 unsigned char* current_abbrev
;
234 for (current_abbrev
= abbrev_data
;
235 current_abbrev
[0] || current_abbrev
[1];
238 if (current_abbrev
>= abbrev_end
)
240 this->failed(_("Debug abbreviations extend beyond "
241 ".debug_abbrev section; failed to reduce "
242 "debug abbreviations"));
246 // Account for the two nulls and advance to the start of the
247 // next abbreviation.
250 // We're eliminating every entry except for compile units, so we
251 // only need to store abbreviations that describe them
252 if (abbrev_type
== elfcpp::DW_TAG_compile_unit
)
254 write_unsigned_LEB_128(&this->data_
, ++this->abbrev_count_
);
255 write_unsigned_LEB_128(&this->data_
, abbrev_type
);
256 // has_children is false for all entries
257 this->data_
.push_back(0);
258 this->abbrev_mapping_
[std::make_pair(abbrev_offset
,
260 std::make_pair(abbrev_count_
, this->data_
.size());
261 this->data_
.insert(this->data_
.end(), abbrev_data
,
264 abbrev_data
= current_abbrev
;
266 gold_assert(LEB_size
== 1);
267 abbrev_data
+= LEB_size
;
269 // Null terminate the list of abbreviations
270 this->data_
.push_back(0);
271 this->set_data_size(data_
.size());
276 Output_reduced_debug_abbrev_section::do_write(Output_file
* of
)
278 off_t offset
= this->offset();
279 off_t data_size
= this->data_size();
280 unsigned char* view
= of
->get_output_view(offset
, data_size
);
282 memcpy(view
, this->postprocessing_buffer(),
283 this->postprocessing_buffer_size());
285 memcpy(view
, &this->data_
.front(), data_size
);
286 of
->write_output_view(offset
, data_size
, view
);
289 // Locates the abbreviation with abbreviation_number abbrev_number in the
290 // abbreviation table at offset abbrev_offset. abbrev_number is updated with
291 // its new abbreviation number and a pointer to the beginning of the
292 // abbreviation is returned.
294 Output_reduced_debug_abbrev_section::get_new_abbrev(
295 uint64_t* abbrev_number
, uint64_t abbrev_offset
)
297 set_final_data_size();
298 std::pair
<uint64_t, uint64_t> abbrev_info
=
299 this->abbrev_mapping_
[std::make_pair(abbrev_offset
, *abbrev_number
)];
300 *abbrev_number
= abbrev_info
.first
;
301 return &this->data_
[abbrev_info
.second
];
304 void Output_reduced_debug_info_section::set_final_data_size()
308 unsigned char* debug_info
= this->postprocessing_buffer();
309 unsigned char* debug_info_end
= (this->postprocessing_buffer()
310 + this->postprocessing_buffer_size());
311 unsigned char* next_compile_unit
;
312 this->write_to_postprocessing_buffer();
314 while (debug_info
< debug_info_end
)
316 uint32_t compile_unit_start
= read_from_pointer
<32>(&debug_info
);
317 // The first 4 bytes of each compile unit determine whether or
318 // not we're using dwarf32 or dwarf64. This is not necessarily
319 // related to whether the binary is 32 or 64 bits.
320 if (compile_unit_start
== 0xFFFFFFFF)
322 // Technically the size can be up to 96 bits. Rather than handle
323 // 96/128 bit integers we just truncate the size at 64 bits.
324 if (0 != read_from_pointer
<32>(&debug_info
))
326 this->failed(_("Extremely large compile unit in debug info; "
327 "failed to reduce debug info"));
330 const int dwarf64_header_size
= sizeof(uint64_t) + sizeof(uint16_t) +
331 sizeof(uint64_t) + sizeof(uint8_t);
332 if (debug_info
+ dwarf64_header_size
>= debug_info_end
)
334 this->failed(_("Debug info extends beyond .debug_info section;"
335 "failed to reduce debug info"));
339 uint64_t compile_unit_size
= read_from_pointer
<64>(&debug_info
);
340 next_compile_unit
= debug_info
+ compile_unit_size
;
341 uint16_t version
= read_from_pointer
<16>(&debug_info
);
342 uint64_t abbrev_offset
= read_from_pointer
<64>(&debug_info
);
343 uint8_t address_size
= read_from_pointer
<8>(&debug_info
);
345 uint64_t abbreviation_number
= read_unsigned_LEB_128(debug_info
,
347 debug_info
+= LEB_size
;
348 unsigned char* die_abbrev
= this->associated_abbrev_
->get_new_abbrev(
349 &abbreviation_number
, abbrev_offset
);
350 unsigned char* die_end
;
351 if (!this->get_die_end(debug_info
, die_abbrev
, &die_end
,
352 debug_info_end
, address_size
, true))
354 this->failed(_("Invalid DIE in debug info; "
355 "failed to reduce debug info"));
359 Insert_into_vector
<32>(&this->data_
, 0xFFFFFFFF);
360 Insert_into_vector
<32>(&this->data_
, 0);
361 Insert_into_vector
<64>(
363 (11 + get_length_as_unsigned_LEB_128(abbreviation_number
)
364 + die_end
- debug_info
));
365 Insert_into_vector
<16>(&this->data_
, version
);
366 Insert_into_vector
<64>(&this->data_
, 0);
367 Insert_into_vector
<8>(&this->data_
, address_size
);
368 write_unsigned_LEB_128(&this->data_
, abbreviation_number
);
369 this->data_
.insert(this->data_
.end(), debug_info
, die_end
);
373 const int dwarf32_header_size
=
374 sizeof(uint16_t) + sizeof(uint32_t) + sizeof(uint8_t);
375 if (debug_info
+ dwarf32_header_size
>= debug_info_end
)
377 this->failed(_("Debug info extends beyond .debug_info section; "
378 "failed to reduce debug info"));
381 uint32_t compile_unit_size
= compile_unit_start
;
382 next_compile_unit
= debug_info
+ compile_unit_size
;
383 uint16_t version
= read_from_pointer
<16>(&debug_info
);
384 uint32_t abbrev_offset
= read_from_pointer
<32>(&debug_info
);
385 uint8_t address_size
= read_from_pointer
<8>(&debug_info
);
387 uint64_t abbreviation_number
= read_unsigned_LEB_128(debug_info
,
389 debug_info
+= LEB_size
;
390 unsigned char* die_abbrev
= this->associated_abbrev_
->get_new_abbrev(
391 &abbreviation_number
, abbrev_offset
);
392 unsigned char* die_end
;
393 if (!this->get_die_end(debug_info
, die_abbrev
, &die_end
,
394 debug_info_end
, address_size
, false))
396 this->failed(_("Invalid DIE in debug info; "
397 "failed to reduce debug info"));
401 Insert_into_vector
<32>(
403 (7 + get_length_as_unsigned_LEB_128(abbreviation_number
)
404 + die_end
- debug_info
));
405 Insert_into_vector
<16>(&this->data_
, version
);
406 Insert_into_vector
<32>(&this->data_
, 0);
407 Insert_into_vector
<8>(&this->data_
, address_size
);
408 write_unsigned_LEB_128(&this->data_
, abbreviation_number
);
409 this->data_
.insert(this->data_
.end(), debug_info
, die_end
);
411 debug_info
= next_compile_unit
;
413 this->set_data_size(data_
.size());
416 void Output_reduced_debug_info_section::do_write(Output_file
* of
)
418 off_t offset
= this->offset();
419 off_t data_size
= this->data_size();
420 unsigned char* view
= of
->get_output_view(offset
, data_size
);
422 memcpy(view
, this->postprocessing_buffer(),
423 this->postprocessing_buffer_size());
425 memcpy(view
, &this->data_
.front(), data_size
);
426 of
->write_output_view(offset
, data_size
, view
);
429 } // End namespace gold.
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