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.
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