* configure.ac (AC_CHECK_FUNCS): Sort into alphabetical order.
[binutils.git] / gold / stringpool.cc
blobd9f40506eb07be90ae218b198cc0fc69bfbedb8b
1 // stringpool.cc -- a string pool for gold
3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@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.
23 #include "gold.h"
25 #include <cstring>
26 #include <algorithm>
27 #include <vector>
29 #include "output.h"
30 #include "parameters.h"
31 #include "stringpool.h"
33 namespace gold
36 template<typename Stringpool_char>
37 Stringpool_template<Stringpool_char>::Stringpool_template()
38 : string_set_(), key_to_offset_(), strings_(), strtab_size_(0),
39 zero_null_(true), optimize_(false)
41 if (parameters->options_valid() && parameters->options().optimize() >= 2)
42 this->optimize_ = true;
45 template<typename Stringpool_char>
46 void
47 Stringpool_template<Stringpool_char>::clear()
49 for (typename std::list<Stringdata*>::iterator p = this->strings_.begin();
50 p != this->strings_.end();
51 ++p)
52 delete[] reinterpret_cast<char*>(*p);
53 this->strings_.clear();
54 this->key_to_offset_.clear();
55 this->string_set_.clear();
58 template<typename Stringpool_char>
59 Stringpool_template<Stringpool_char>::~Stringpool_template()
61 this->clear();
64 // Resize the internal hashtable with the expectation we'll get n new
65 // elements. Note that the hashtable constructor takes a "number of
66 // buckets you'd like," rather than "number of elements you'd like,"
67 // but that's the best we can do.
69 template<typename Stringpool_char>
70 void
71 Stringpool_template<Stringpool_char>::reserve(unsigned int n)
73 this->key_to_offset_.reserve(n);
75 #if defined(HAVE_TR1_UNORDERED_MAP)
76 // rehash() implementation is broken in gcc 4.0.3's stl
77 //this->string_set_.rehash(this->string_set_.size() + n);
78 //return;
79 #elif defined(HAVE_EXT_HASH_MAP)
80 this->string_set_.resize(this->string_set_.size() + n);
81 return;
82 #endif
84 // This is the generic "reserve" code, if no #ifdef above triggers.
85 String_set_type new_string_set(this->string_set_.size() + n);
86 new_string_set.insert(this->string_set_.begin(), this->string_set_.end());
87 this->string_set_.swap(new_string_set);
90 // Return the length of a string of arbitrary character type.
92 template<typename Stringpool_char>
93 size_t
94 Stringpool_template<Stringpool_char>::string_length(const Stringpool_char* p)
96 size_t len = 0;
97 for (; *p != 0; ++p)
98 ++len;
99 return len;
102 // Specialize string_length for char. Maybe we could just use
103 // std::char_traits<>::length?
105 template<>
106 inline size_t
107 Stringpool_template<char>::string_length(const char* p)
109 return strlen(p);
112 // Compare two strings of arbitrary character type for equality.
114 template<typename Stringpool_char>
115 bool
116 Stringpool_template<Stringpool_char>::string_equal(const Stringpool_char* s1,
117 const Stringpool_char* s2)
119 while (*s1 != 0)
120 if (*s1++ != *s2++)
121 return false;
122 return *s2 == 0;
125 // Specialize string_equal for char.
127 template<>
128 inline bool
129 Stringpool_template<char>::string_equal(const char* s1, const char* s2)
131 return strcmp(s1, s2) == 0;
134 // Equality comparison function for the hash table.
136 template<typename Stringpool_char>
137 inline bool
138 Stringpool_template<Stringpool_char>::Stringpool_eq::operator()(
139 const Hashkey& h1,
140 const Hashkey& h2) const
142 return (h1.hash_code == h2.hash_code
143 && h1.length == h2.length
144 && (h1.string == h2.string
145 || memcmp(h1.string, h2.string,
146 h1.length * sizeof(Stringpool_char)) == 0));
149 // Hash function. The length is in characters, not bytes.
151 template<typename Stringpool_char>
152 size_t
153 Stringpool_template<Stringpool_char>::string_hash(const Stringpool_char* s,
154 size_t length)
156 return gold::string_hash<Stringpool_char>(s, length);
159 // Add the string S to the list of canonical strings. Return a
160 // pointer to the canonical string. If PKEY is not NULL, set *PKEY to
161 // the key. LENGTH is the length of S in characters. Note that S may
162 // not be NUL terminated.
164 template<typename Stringpool_char>
165 const Stringpool_char*
166 Stringpool_template<Stringpool_char>::add_string(const Stringpool_char* s,
167 size_t len)
169 // We are in trouble if we've already computed the string offsets.
170 gold_assert(this->strtab_size_ == 0);
172 // The size we allocate for a new Stringdata.
173 const size_t buffer_size = 1000;
174 // The amount we multiply the Stringdata index when calculating the
175 // key.
176 const size_t key_mult = 1024;
177 gold_assert(key_mult >= buffer_size);
179 // Convert len to the number of bytes we need to allocate, including
180 // the null character.
181 len = (len + 1) * sizeof(Stringpool_char);
183 size_t alc;
184 bool front = true;
185 if (len > buffer_size)
187 alc = sizeof(Stringdata) + len;
188 front = false;
190 else if (this->strings_.empty())
191 alc = sizeof(Stringdata) + buffer_size;
192 else
194 Stringdata *psd = this->strings_.front();
195 if (len > psd->alc - psd->len)
196 alc = sizeof(Stringdata) + buffer_size;
197 else
199 char* ret = psd->data + psd->len;
200 memcpy(ret, s, len - sizeof(Stringpool_char));
201 memset(ret + len - sizeof(Stringpool_char), 0,
202 sizeof(Stringpool_char));
204 psd->len += len;
206 return reinterpret_cast<const Stringpool_char*>(ret);
210 Stringdata *psd = reinterpret_cast<Stringdata*>(new char[alc]);
211 psd->alc = alc - sizeof(Stringdata);
212 memcpy(psd->data, s, len - sizeof(Stringpool_char));
213 memset(psd->data + len - sizeof(Stringpool_char), 0,
214 sizeof(Stringpool_char));
215 psd->len = len;
217 if (front)
218 this->strings_.push_front(psd);
219 else
220 this->strings_.push_back(psd);
222 return reinterpret_cast<const Stringpool_char*>(psd->data);
225 // Add a string to a string pool.
227 template<typename Stringpool_char>
228 const Stringpool_char*
229 Stringpool_template<Stringpool_char>::add(const Stringpool_char* s, bool copy,
230 Key* pkey)
232 return this->add_with_length(s, string_length(s), copy, pkey);
235 template<typename Stringpool_char>
236 const Stringpool_char*
237 Stringpool_template<Stringpool_char>::add_with_length(const Stringpool_char* s,
238 size_t length,
239 bool copy,
240 Key* pkey)
242 typedef std::pair<typename String_set_type::iterator, bool> Insert_type;
244 // We add 1 so that 0 is always invalid.
245 const Key k = this->key_to_offset_.size() + 1;
247 if (!copy)
249 // When we don't need to copy the string, we can call insert
250 // directly.
252 std::pair<Hashkey, Hashval> element(Hashkey(s, length), k);
254 Insert_type ins = this->string_set_.insert(element);
256 typename String_set_type::const_iterator p = ins.first;
258 if (ins.second)
260 // We just added the string. The key value has now been
261 // used.
262 this->key_to_offset_.push_back(0);
264 else
266 gold_assert(k != p->second);
269 if (pkey != NULL)
270 *pkey = p->second;
271 return p->first.string;
274 // When we have to copy the string, we look it up twice in the hash
275 // table. The problem is that we can't insert S before we
276 // canonicalize it by copying it into the canonical list. The hash
277 // code will only be computed once.
279 Hashkey hk(s, length);
280 typename String_set_type::const_iterator p = this->string_set_.find(hk);
281 if (p != this->string_set_.end())
283 if (pkey != NULL)
284 *pkey = p->second;
285 return p->first.string;
288 this->key_to_offset_.push_back(0);
290 hk.string = this->add_string(s, length);
291 // The contents of the string stay the same, so we don't need to
292 // adjust hk.hash_code or hk.length.
294 std::pair<Hashkey, Hashval> element(hk, k);
296 Insert_type ins = this->string_set_.insert(element);
297 gold_assert(ins.second);
299 if (pkey != NULL)
300 *pkey = k;
301 return hk.string;
304 template<typename Stringpool_char>
305 const Stringpool_char*
306 Stringpool_template<Stringpool_char>::find(const Stringpool_char* s,
307 Key* pkey) const
309 Hashkey hk(s);
310 typename String_set_type::const_iterator p = this->string_set_.find(hk);
311 if (p == this->string_set_.end())
312 return NULL;
314 if (pkey != NULL)
315 *pkey = p->second;
317 return p->first.string;
320 // Comparison routine used when sorting into an ELF strtab. We want
321 // to sort this so that when one string is a suffix of another, we
322 // always see the shorter string immediately after the longer string.
323 // For example, we want to see these strings in this order:
324 // abcd
325 // cd
326 // d
327 // When strings are not suffixes, we don't care what order they are
328 // in, but we need to ensure that suffixes wind up next to each other.
329 // So we do a reversed lexicographic sort on the reversed string.
331 template<typename Stringpool_char>
332 bool
333 Stringpool_template<Stringpool_char>::Stringpool_sort_comparison::operator()(
334 const Stringpool_sort_info& sort_info1,
335 const Stringpool_sort_info& sort_info2) const
337 const Hashkey& h1(sort_info1->first);
338 const Hashkey& h2(sort_info2->first);
339 const Stringpool_char* s1 = h1.string;
340 const Stringpool_char* s2 = h2.string;
341 const size_t len1 = h1.length;
342 const size_t len2 = h2.length;
343 const size_t minlen = len1 < len2 ? len1 : len2;
344 const Stringpool_char* p1 = s1 + len1 - 1;
345 const Stringpool_char* p2 = s2 + len2 - 1;
346 for (size_t i = minlen; i > 0; --i, --p1, --p2)
348 if (*p1 != *p2)
349 return *p1 > *p2;
351 return len1 > len2;
354 // Return whether s1 is a suffix of s2.
356 template<typename Stringpool_char>
357 bool
358 Stringpool_template<Stringpool_char>::is_suffix(const Stringpool_char* s1,
359 size_t len1,
360 const Stringpool_char* s2,
361 size_t len2)
363 if (len1 > len2)
364 return false;
365 return memcmp(s1, s2 + len2 - len1, len1 * sizeof(Stringpool_char)) == 0;
368 // Turn the stringpool into an ELF strtab: determine the offsets of
369 // each string in the table.
371 template<typename Stringpool_char>
372 void
373 Stringpool_template<Stringpool_char>::set_string_offsets()
375 if (this->strtab_size_ != 0)
377 // We've already computed the offsets.
378 return;
381 const size_t charsize = sizeof(Stringpool_char);
383 // Offset 0 may be reserved for the empty string.
384 section_offset_type offset = this->zero_null_ ? charsize : 0;
386 // Sorting to find suffixes can take over 25% of the total CPU time
387 // used by the linker. Since it's merely an optimization to reduce
388 // the strtab size, and gives a relatively small benefit (it's
389 // typically rare for a symbol to be a suffix of another), we only
390 // take the time to sort when the user asks for heavy optimization.
391 if (!this->optimize_)
393 for (typename String_set_type::iterator curr = this->string_set_.begin();
394 curr != this->string_set_.end();
395 curr++)
397 section_offset_type* poff = &this->key_to_offset_[curr->second - 1];
398 if (this->zero_null_ && curr->first.string[0] == 0)
399 *poff = 0;
400 else
402 *poff = offset;
403 offset += (curr->first.length + 1) * charsize;
407 else
409 size_t count = this->string_set_.size();
411 std::vector<Stringpool_sort_info> v;
412 v.reserve(count);
414 for (typename String_set_type::iterator p = this->string_set_.begin();
415 p != this->string_set_.end();
416 ++p)
417 v.push_back(Stringpool_sort_info(p));
419 std::sort(v.begin(), v.end(), Stringpool_sort_comparison());
421 section_offset_type last_offset = -1;
422 for (typename std::vector<Stringpool_sort_info>::iterator last = v.end(),
423 curr = v.begin();
424 curr != v.end();
425 last = curr++)
427 section_offset_type this_offset;
428 if (this->zero_null_ && (*curr)->first.string[0] == 0)
429 this_offset = 0;
430 else if (last != v.end()
431 && is_suffix((*curr)->first.string,
432 (*curr)->first.length,
433 (*last)->first.string,
434 (*last)->first.length))
435 this_offset = (last_offset
436 + (((*last)->first.length - (*curr)->first.length)
437 * charsize));
438 else
440 this_offset = offset;
441 offset += ((*curr)->first.length + 1) * charsize;
443 this->key_to_offset_[(*curr)->second - 1] = this_offset;
444 last_offset = this_offset;
448 this->strtab_size_ = offset;
451 // Get the offset of a string in the ELF strtab. The string must
452 // exist.
454 template<typename Stringpool_char>
455 section_offset_type
456 Stringpool_template<Stringpool_char>::get_offset(const Stringpool_char* s)
457 const
459 return this->get_offset_with_length(s, string_length(s));
462 template<typename Stringpool_char>
463 section_offset_type
464 Stringpool_template<Stringpool_char>::get_offset_with_length(
465 const Stringpool_char* s,
466 size_t length) const
468 gold_assert(this->strtab_size_ != 0);
469 Hashkey hk(s, length);
470 typename String_set_type::const_iterator p = this->string_set_.find(hk);
471 if (p != this->string_set_.end())
472 return this->key_to_offset_[p->second - 1];
473 gold_unreachable();
476 // Write the ELF strtab into the buffer.
478 template<typename Stringpool_char>
479 void
480 Stringpool_template<Stringpool_char>::write_to_buffer(
481 unsigned char* buffer,
482 section_size_type bufsize)
484 gold_assert(this->strtab_size_ != 0);
485 gold_assert(bufsize >= this->strtab_size_);
486 if (this->zero_null_)
487 buffer[0] = '\0';
488 for (typename String_set_type::const_iterator p = this->string_set_.begin();
489 p != this->string_set_.end();
490 ++p)
492 const int len = (p->first.length + 1) * sizeof(Stringpool_char);
493 const section_offset_type offset = this->key_to_offset_[p->second - 1];
494 gold_assert(static_cast<section_size_type>(offset) + len
495 <= this->strtab_size_);
496 memcpy(buffer + offset, p->first.string, len);
500 // Write the ELF strtab into the output file at the specified offset.
502 template<typename Stringpool_char>
503 void
504 Stringpool_template<Stringpool_char>::write(Output_file* of, off_t offset)
506 gold_assert(this->strtab_size_ != 0);
507 unsigned char* view = of->get_output_view(offset, this->strtab_size_);
508 this->write_to_buffer(view, this->strtab_size_);
509 of->write_output_view(offset, this->strtab_size_, view);
512 // Print statistical information to stderr. This is used for --stats.
514 template<typename Stringpool_char>
515 void
516 Stringpool_template<Stringpool_char>::print_stats(const char* name) const
518 #if defined(HAVE_TR1_UNORDERED_MAP) || defined(HAVE_EXT_HASH_MAP)
519 fprintf(stderr, _("%s: %s entries: %zu; buckets: %zu\n"),
520 program_name, name, this->string_set_.size(),
521 this->string_set_.bucket_count());
522 #else
523 fprintf(stderr, _("%s: %s entries: %zu\n"),
524 program_name, name, this->table_.size());
525 #endif
526 fprintf(stderr, _("%s: %s Stringdata structures: %zu\n"),
527 program_name, name, this->strings_.size());
530 // Instantiate the templates we need.
532 template
533 class Stringpool_template<char>;
535 template
536 class Stringpool_template<uint16_t>;
538 template
539 class Stringpool_template<uint32_t>;
541 } // End namespace gold.