1 // stringpool.cc -- a string pool for gold
10 #include "stringpool.h"
15 template<typename Stringpool_char>
16 Stringpool_template<Stringpool_char>::Stringpool_template(bool zero_null)
17 : string_set_(), strings_(), strtab_size_(0), next_index_(1),
22 template<typename Stringpool_char>
23 Stringpool_template<Stringpool_char>::~Stringpool_template()
25 for (typename std::list<Stringdata*>::iterator p = this->strings_.begin();
26 p != this->strings_.end();
28 delete[] reinterpret_cast<char*>(*p);
31 // Return the length of a string of arbitrary character type.
33 template<typename Stringpool_char>
35 Stringpool_template<Stringpool_char>::string_length(const Stringpool_char* p)
43 // Specialize string_length for char. Maybe we could just use
44 // std::char_traits<>::length?
48 Stringpool_template<char>::string_length(const char* p)
53 // Equality comparison function.
55 template<typename Stringpool_char>
57 Stringpool_template<Stringpool_char>::Stringpool_eq::operator()(
58 const Stringpool_char* s1,
59 const Stringpool_char* s2) const
67 // Specialize equality comparison for char.
71 Stringpool_template<char>::Stringpool_eq::operator()(const char* s1,
74 return strcmp(s1, s2) == 0;
79 template<typename Stringpool_char>
81 Stringpool_template<Stringpool_char>::Stringpool_hash::operator()(
82 const Stringpool_char* s) const
84 // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
85 if (sizeof(size_t) == 8)
87 size_t result = static_cast<size_t>(14695981039346656037ULL);
90 const char* p = reinterpret_cast<const char*>(s);
91 for (size_t i = 0; i < sizeof(Stringpool_char); ++i)
93 result &= (size_t) *p++;
94 result *= 1099511628211ULL;
102 size_t result = 2166136261UL;
105 const char* p = reinterpret_cast<const char*>(s);
106 for (size_t i = 0; i < sizeof(Stringpool_char); ++i)
108 result ^= (size_t) *p++;
109 result *= 16777619UL;
117 // Add a string to the list of canonical strings. Return a pointer to
118 // the canonical string. If PKEY is not NULL, set *PKEY to the key.
120 template<typename Stringpool_char>
121 const Stringpool_char*
122 Stringpool_template<Stringpool_char>::add_string(const Stringpool_char* s,
125 // We are in trouble if we've already computed the string offsets.
126 gold_assert(this->strtab_size_ == 0);
128 // The size we allocate for a new Stringdata.
129 const size_t buffer_size = 1000;
130 // The amount we multiply the Stringdata index when calculating the
132 const size_t key_mult = 1024;
133 gold_assert(key_mult >= buffer_size);
135 size_t len = (string_length(s) + 1) * sizeof(Stringpool_char);
139 if (len > buffer_size)
141 alc = sizeof(Stringdata) + len;
144 else if (this->strings_.empty())
145 alc = sizeof(Stringdata) + buffer_size;
148 Stringdata *psd = this->strings_.front();
149 if (len > psd->alc - psd->len)
150 alc = sizeof(Stringdata) + buffer_size;
153 char* ret = psd->data + psd->len;
157 *pkey = psd->index * key_mult + psd->len;
161 return reinterpret_cast<const Stringpool_char*>(ret);
165 Stringdata *psd = reinterpret_cast<Stringdata*>(new char[alc]);
166 psd->alc = alc - sizeof(Stringdata);
167 memcpy(psd->data, s, len);
169 psd->index = this->next_index_;
173 *pkey = psd->index * key_mult;
176 this->strings_.push_front(psd);
178 this->strings_.push_back(psd);
180 return reinterpret_cast<const Stringpool_char*>(psd->data);
183 // Add a string to a string pool.
185 template<typename Stringpool_char>
186 const Stringpool_char*
187 Stringpool_template<Stringpool_char>::add(const Stringpool_char* s, Key* pkey)
189 // FIXME: This will look up the entry twice in the hash table. The
190 // problem is that we can't insert S before we canonicalize it. I
191 // don't think there is a way to handle this correctly with
192 // unordered_map, so this should be replaced with custom code to do
193 // what we need, which is to return the empty slot.
195 typename String_set_type::const_iterator p = this->string_set_.find(s);
196 if (p != this->string_set_.end())
199 *pkey = p->second.first;
204 const Stringpool_char* ret = this->add_string(s, &k);
206 const off_t ozero = 0;
207 std::pair<const Stringpool_char*, Val> element(ret,
208 std::make_pair(k, ozero));
209 std::pair<typename String_set_type::iterator, bool> ins =
210 this->string_set_.insert(element);
211 gold_assert(ins.second);
219 // Add a prefix of a string to a string pool.
221 template<typename Stringpool_char>
222 const Stringpool_char*
223 Stringpool_template<Stringpool_char>::add(const Stringpool_char* s, size_t len,
226 // FIXME: This implementation should be rewritten when we rewrite
227 // the hash table to avoid copying.
228 std::basic_string<Stringpool_char> st(s, len);
229 return this->add(st, pkey);
232 template<typename Stringpool_char>
233 const Stringpool_char*
234 Stringpool_template<Stringpool_char>::find(const Stringpool_char* s,
237 typename String_set_type::const_iterator p = this->string_set_.find(s);
238 if (p == this->string_set_.end())
242 *pkey = p->second.first;
247 // Comparison routine used when sorting into an ELF strtab. We want
248 // to sort this so that when one string is a suffix of another, we
249 // always see the shorter string immediately after the longer string.
250 // For example, we want to see these strings in this order:
254 // When strings are not suffixes, we don't care what order they are
255 // in, but we need to ensure that suffixes wind up next to each other.
256 // So we do a reversed lexicographic sort on the reversed string.
258 template<typename Stringpool_char>
260 Stringpool_template<Stringpool_char>::Stringpool_sort_comparison::operator()(
261 typename String_set_type::iterator it1,
262 typename String_set_type::iterator it2) const
264 const Stringpool_char* s1 = it1->first;
265 const Stringpool_char* s2 = it2->first;
266 size_t len1 = string_length(s1);
267 size_t len2 = string_length(s2);
268 size_t minlen = len1 < len2 ? len1 : len2;
269 const Stringpool_char* p1 = s1 + len1 - 1;
270 const Stringpool_char* p2 = s2 + len2 - 1;
271 for (size_t i = minlen; i > 0; --i, --p1, --p2)
279 // Return whether s1 is a suffix of s2.
281 template<typename Stringpool_char>
283 Stringpool_template<Stringpool_char>::is_suffix(const Stringpool_char* s1,
284 const Stringpool_char* s2)
286 size_t len1 = string_length(s1);
287 size_t len2 = string_length(s2);
290 return memcmp(s1, s2 + len2 - len1, len1 * sizeof(Stringpool_char)) == 0;
293 // Turn the stringpool into an ELF strtab: determine the offsets of
294 // each string in the table.
296 template<typename Stringpool_char>
298 Stringpool_template<Stringpool_char>::set_string_offsets()
300 if (this->strtab_size_ != 0)
302 // We've already computed the offsets.
306 size_t count = this->string_set_.size();
308 std::vector<typename String_set_type::iterator> v;
311 for (typename String_set_type::iterator p = this->string_set_.begin();
312 p != this->string_set_.end();
316 std::sort(v.begin(), v.end(), Stringpool_sort_comparison());
318 const size_t charsize = sizeof(Stringpool_char);
320 // Offset 0 may be reserved for the empty string.
321 off_t offset = this->zero_null_ ? charsize : 0;
322 for (size_t i = 0; i < count; ++i)
324 if (this->zero_null_ && v[i]->first[0] == 0)
325 v[i]->second.second = 0;
326 else if (i > 0 && is_suffix(v[i]->first, v[i - 1]->first))
327 v[i]->second.second = (v[i - 1]->second.second
328 + ((string_length(v[i - 1]->first)
329 - string_length(v[i]->first))
333 v[i]->second.second = offset;
334 offset += (string_length(v[i]->first) + 1) * charsize;
338 this->strtab_size_ = offset;
341 // Get the offset of a string in the ELF strtab. The string must
344 template<typename Stringpool_char>
346 Stringpool_template<Stringpool_char>::get_offset(const Stringpool_char* s)
349 gold_assert(this->strtab_size_ != 0);
350 typename String_set_type::const_iterator p = this->string_set_.find(s);
351 if (p != this->string_set_.end())
352 return p->second.second;
356 // Write the ELF strtab into the output file at the specified offset.
358 template<typename Stringpool_char>
360 Stringpool_template<Stringpool_char>::write(Output_file* of, off_t offset)
362 gold_assert(this->strtab_size_ != 0);
363 unsigned char* viewu = of->get_output_view(offset, this->strtab_size_);
364 char* view = reinterpret_cast<char*>(viewu);
365 if (this->zero_null_)
367 for (typename String_set_type::const_iterator p = this->string_set_.begin();
368 p != this->string_set_.end();
370 memcpy(view + p->second.second, p->first,
371 (string_length(p->first) + 1) * sizeof(Stringpool_char));
372 of->write_output_view(offset, this->strtab_size_, viewu);
375 // Instantiate the templates we need.
378 class Stringpool_template<char>;
381 class Stringpool_template<uint16_t>;
384 class Stringpool_template<uint32_t>;
386 } // End namespace gold.