return strlen(p);
}
-// Equality comparison function.
+// Compare two strings of arbitrary character type for equality.
template<typename Stringpool_char>
bool
-Stringpool_template<Stringpool_char>::Stringpool_eq::operator()(
- const Stringpool_char* s1,
- const Stringpool_char* s2) const
+Stringpool_template<Stringpool_char>::string_equal(const Stringpool_char* s1,
+ const Stringpool_char* s2)
{
while (*s1 != 0)
if (*s1++ != *s2++)
return *s2 == 0;
}
-// Specialize equality comparison for char.
+// Specialize string_equal for char.
template<>
-bool
-Stringpool_template<char>::Stringpool_eq::operator()(const char* s1,
- const char* s2) const
+inline bool
+Stringpool_template<char>::string_equal(const char* s1, const char* s2)
{
return strcmp(s1, s2) == 0;
}
-// Hash function.
+// Equality comparison function for the hash table.
+
+template<typename Stringpool_char>
+inline bool
+Stringpool_template<Stringpool_char>::Stringpool_eq::operator()(
+ const Hashkey& h1,
+ const Hashkey& h2) const
+{
+ return (h1.hash_code == h2.hash_code
+ && h1.length == h2.length
+ && memcmp(h1.string, h2.string,
+ h1.length * sizeof(Stringpool_char)) == 0);
+}
+
+// Hash function. The length is in characters, not bytes.
template<typename Stringpool_char>
size_t
-Stringpool_template<Stringpool_char>::Stringpool_hash::operator()(
- const Stringpool_char* s) const
+Stringpool_template<Stringpool_char>::string_hash(const Stringpool_char* s,
+ size_t length)
{
// Fowler/Noll/Vo (FNV) hash (type FNV-1a).
+ const unsigned char* p = reinterpret_cast<const unsigned char*>(s);
if (sizeof(size_t) > 4)
{
size_t result = static_cast<size_t>(14695981039346656037ULL);
- while (*s != 0)
+ for (size_t i = 0; i < length * sizeof(Stringpool_char); ++i)
{
- const char* p = reinterpret_cast<const char*>(s);
- for (size_t i = 0; i < sizeof(Stringpool_char); ++i)
- {
- result ^= (size_t) *p++;
- result *= 1099511628211ULL;
- }
- ++s;
+ result ^= static_cast<size_t>(*p++);
+ result *= 1099511628211ULL;
}
return result;
}
else
{
size_t result = 2166136261UL;
- while (*s != 0)
+ for (size_t i = 0; i < length * sizeof(Stringpool_char); ++i)
{
- const char* p = reinterpret_cast<const char*>(s);
- for (size_t i = 0; i < sizeof(Stringpool_char); ++i)
- {
- result ^= (size_t) *p++;
- result *= 16777619UL;
- }
- ++s;
+ result ^= static_cast<size_t>(*p++);
+ result *= 16777619UL;
}
return result;
}
}
-// Add a string to the list of canonical strings. Return a pointer to
-// the canonical string. If PKEY is not NULL, set *PKEY to the key.
+// Add the string S to the list of canonical strings. Return a
+// pointer to the canonical string. If PKEY is not NULL, set *PKEY to
+// the key. LENGTH is the length of S in characters. Note that S may
+// not be NUL terminated.
template<typename Stringpool_char>
const Stringpool_char*
Stringpool_template<Stringpool_char>::add_string(const Stringpool_char* s,
+ size_t len,
Key* pkey)
{
// We are in trouble if we've already computed the string offsets.
const size_t key_mult = 1024;
gold_assert(key_mult >= buffer_size);
- size_t len = (string_length(s) + 1) * sizeof(Stringpool_char);
+ // Convert len to the number of bytes we need to allocate, including
+ // the null character.
+ len = (len + 1) * sizeof(Stringpool_char);
size_t alc;
bool front = true;
else
{
char* ret = psd->data + psd->len;
- memcpy(ret, s, len);
+ memcpy(ret, s, len - sizeof(Stringpool_char));
+ memset(ret + len - sizeof(Stringpool_char), 0,
+ sizeof(Stringpool_char));
if (pkey != NULL)
*pkey = psd->index * key_mult + psd->len;
Stringdata *psd = reinterpret_cast<Stringdata*>(new char[alc]);
psd->alc = alc - sizeof(Stringdata);
- memcpy(psd->data, s, len);
+ memcpy(psd->data, s, len - sizeof(Stringpool_char));
+ memset(psd->data + len - sizeof(Stringpool_char), 0,
+ sizeof(Stringpool_char));
psd->len = len;
psd->index = this->next_index_;
++this->next_index_;
Stringpool_template<Stringpool_char>::add(const Stringpool_char* s, bool copy,
Key* pkey)
{
- // FIXME: This will look up the entry twice in the hash table. The
- // problem is that we can't insert S before we canonicalize it. I
- // don't think there is a way to handle this correctly with
- // unordered_map, so this should be replaced with custom code to do
- // what we need, which is to return the empty slot.
+ typedef std::pair<typename String_set_type::iterator, bool> Insert_type;
- typename String_set_type::const_iterator p = this->string_set_.find(s);
- if (p != this->string_set_.end())
+ if (!copy)
{
- if (pkey != NULL)
- *pkey = p->second.first;
- return p->first;
- }
+ // When we don't need to copy the string, we can call insert
+ // directly.
- Key k;
- const Stringpool_char* ret;
- if (copy)
- ret = this->add_string(s, &k);
- else
- {
- ret = s;
- k = this->next_uncopied_key_;
- --this->next_uncopied_key_;
- }
+ const Key k = this->next_uncopied_key_;
+ const off_t ozero = 0;
+ std::pair<Hashkey, Hashval> element(Hashkey(s),
+ std::make_pair(k, ozero));
- const off_t ozero = 0;
- std::pair<const Stringpool_char*, Val> element(ret,
- std::make_pair(k, ozero));
- std::pair<typename String_set_type::iterator, bool> ins =
- this->string_set_.insert(element);
- gold_assert(ins.second);
+ Insert_type ins = this->string_set_.insert(element);
- if (pkey != NULL)
- *pkey = k;
+ typename String_set_type::const_iterator p = ins.first;
+
+ if (ins.second)
+ {
+ // We just added the string. The key value has now been
+ // used.
+ --this->next_uncopied_key_;
+ }
+ else
+ {
+ gold_assert(k != p->second.first);
+ }
+
+ if (pkey != NULL)
+ *pkey = p->second.first;
+ return p->first.string;
+ }
- return ret;
+ return this->add_prefix(s, string_length(s), pkey);
}
// Add a prefix of a string to a string pool.
size_t len,
Key* pkey)
{
- // FIXME: This implementation should be rewritten when we rewrite
- // the hash table to avoid copying.
- std::basic_string<Stringpool_char> st(s, len);
- return this->add(st.c_str(), true, pkey);
+ // When adding an entry, this will look it up twice in the hash
+ // table. The problem is that we can't insert S before we
+ // canonicalize it by copying it into the canonical list. The hash
+ // code will only be computed once, so this isn't all that
+ // expensive.
+
+ Hashkey hk(s, len);
+ typename String_set_type::const_iterator p = this->string_set_.find(hk);
+ if (p != this->string_set_.end())
+ {
+ if (pkey != NULL)
+ *pkey = p->second.first;
+ return p->first.string;
+ }
+
+ Key k;
+ hk.string = this->add_string(s, len, &k);
+ // The contents of the string stay the same, so we don't need to
+ // adjust hk.hash_code or hk.length.
+
+ const off_t ozero = 0;
+ std::pair<Hashkey, Hashval> element(hk, std::make_pair(k, ozero));
+
+ typedef std::pair<typename String_set_type::iterator, bool> Insert_type;
+ Insert_type ins = this->string_set_.insert(element);
+ gold_assert(ins.second);
+
+ if (pkey != NULL)
+ *pkey = k;
+ return hk.string;
}
template<typename Stringpool_char>
Stringpool_template<Stringpool_char>::find(const Stringpool_char* s,
Key* pkey) const
{
- typename String_set_type::const_iterator p = this->string_set_.find(s);
+ Hashkey hk(s);
+ typename String_set_type::const_iterator p = this->string_set_.find(hk);
if (p == this->string_set_.end())
return NULL;
if (pkey != NULL)
*pkey = p->second.first;
- return p->first;
+ return p->first.string;
}
// Comparison routine used when sorting into an ELF strtab. We want
const Stringpool_sort_info& sort_info1,
const Stringpool_sort_info& sort_info2) const
{
- const Stringpool_char* s1 = sort_info1.it->first;
- const Stringpool_char* s2 = sort_info2.it->first;
- const size_t len1 = sort_info1.string_length;
- const size_t len2 = sort_info2.string_length;
+ const Hashkey& h1(sort_info1->first);
+ const Hashkey& h2(sort_info2->first);
+ const Stringpool_char* s1 = h1.string;
+ const Stringpool_char* s2 = h2.string;
+ const size_t len1 = h1.length;
+ const size_t len2 = h2.length;
const size_t minlen = len1 < len2 ? len1 : len2;
const Stringpool_char* p1 = s1 + len1 - 1;
const Stringpool_char* p2 = s2 + len2 - 1;
curr != this->string_set_.end();
curr++)
{
- if (this->zero_null_ && curr->first[0] == 0)
+ if (this->zero_null_ && curr->first.string[0] == 0)
curr->second.second = 0;
else
{
curr->second.second = offset;
- offset += (string_length(curr->first) + 1) * charsize;
+ offset += (curr->first.length + 1) * charsize;
}
}
}
for (typename String_set_type::iterator p = this->string_set_.begin();
p != this->string_set_.end();
++p)
- v.push_back(Stringpool_sort_info(p, string_length(p->first)));
+ v.push_back(Stringpool_sort_info(p));
std::sort(v.begin(), v.end(), Stringpool_sort_comparison());
curr != v.end();
last = curr++)
{
- if (this->zero_null_ && curr->it->first[0] == 0)
- curr->it->second.second = 0;
+ if (this->zero_null_ && (*curr)->first.string[0] == 0)
+ (*curr)->second.second = 0;
else if (last != v.end()
- && is_suffix(curr->it->first, curr->string_length,
- last->it->first, last->string_length))
- curr->it->second.second = (last->it->second.second
- + ((last->string_length
- - curr->string_length)
- * charsize));
+ && is_suffix((*curr)->first.string,
+ (*curr)->first.length,
+ (*last)->first.string,
+ (*last)->first.length))
+ (*curr)->second.second = ((*last)->second.second
+ + (((*last)->first.length
+ - (*curr)->first.length)
+ * charsize));
else
{
- curr->it->second.second = offset;
- offset += (curr->string_length + 1) * charsize;
+ (*curr)->second.second = offset;
+ offset += ((*curr)->first.length + 1) * charsize;
}
}
}
p != this->string_set_.end();
++p)
{
- const int len = (string_length(p->first) + 1) * sizeof(Stringpool_char);
+ const int len = (p->first.length + 1) * sizeof(Stringpool_char);
gold_assert(p->second.second + len <= this->strtab_size_);
- memcpy(buffer + p->second.second, p->first, len);
+ memcpy(buffer + p->second.second, p->first.string, len);
}
}
static size_t
string_length(const Stringpool_char*);
+ // Return whether two strings are equal.
+ static bool
+ string_equal(const Stringpool_char*, const Stringpool_char*);
+
+ // Compute a hash code for a string. LENGTH is the length of the
+ // string in characters.
+ static size_t
+ string_hash(const Stringpool_char*, size_t length);
+
// We store the actual data in a list of these buffers.
struct Stringdata
{
// Copy a string into the buffers, returning a canonical string.
const Stringpool_char*
- add_string(const Stringpool_char*, Key*);
+ add_string(const Stringpool_char*, size_t, Key*);
+
+ // Return whether s1 is a suffix of s2.
+ static bool
+ is_suffix(const Stringpool_char* s1, size_t len1,
+ const Stringpool_char* s2, size_t len2);
+
+ // The hash table key includes the string, the length of the string,
+ // and the hash code for the string. We put the hash code
+ // explicitly into the key so that we can do a find()/insert()
+ // sequence without having to recompute the hash. Computing the
+ // hash code is a significant user of CPU time in the linker.
+ struct Hashkey
+ {
+ const Stringpool_char* string;
+ // Length is in characters, not bytes.
+ size_t length;
+ size_t hash_code;
+
+ // This goes in an STL container, so we need a default
+ // constructor.
+ Hashkey()
+ : string(NULL), length(0), hash_code(0)
+ { }
+
+ // Note that these constructors are relatively expensive, because
+ // they compute the hash code.
+ Hashkey(const Stringpool_char* s)
+ : string(s), length(string_length(s)), hash_code(string_hash(s, length))
+ { }
+
+ Hashkey(const Stringpool_char* s, size_t len)
+ : string(s), length(len), hash_code(string_hash(s, len))
+ { }
+ };
- // Hash function.
+ // Hash function. This is trivial, since we have already computed
+ // the hash.
struct Stringpool_hash
{
size_t
- operator()(const Stringpool_char*) const;
+ operator()(const Hashkey& hk) const
+ { return hk.hash_code; }
};
// Equality comparison function for hash table.
struct Stringpool_eq
{
bool
- operator()(const Stringpool_char* p1, const Stringpool_char* p2) const;
+ operator()(const Hashkey&, const Hashkey&) const;
};
- // Return whether s1 is a suffix of s2.
- static bool
- is_suffix(const Stringpool_char* s1, size_t len1,
- const Stringpool_char* s2, size_t len2);
-
- // The hash table is a map from string names to a pair of Key and
- // string table offsets. We only use the offsets if we turn this
- // into an string table section.
+ // The hash table is a map from strings to a pair of Key and string
+ // table offsets. We only use the offsets if we turn this into an
+ // string table section.
- typedef std::pair<Key, off_t> Val;
+ typedef std::pair<Key, off_t> Hashval;
-#ifdef HAVE_TR1_UNORDERED_SET
- typedef Unordered_map<const Stringpool_char*, Val, Stringpool_hash,
- Stringpool_eq,
- std::allocator<std::pair<const Stringpool_char* const,
- Val> >,
- true> String_set_type;
-#else
- typedef Unordered_map<const Stringpool_char*, Val, Stringpool_hash,
+ typedef Unordered_map<Hashkey, Hashval, Stringpool_hash,
Stringpool_eq> String_set_type;
-#endif
- // Comparison routine used when sorting into a string table. We
- // store string-sizes in the sort-vector so we don't have to
- // recompute them log(n) times as we sort.
- struct Stringpool_sort_info
- {
- typename String_set_type::iterator it;
- size_t string_length;
- Stringpool_sort_info(typename String_set_type::iterator i, size_t s)
- : it(i), string_length(s)
- { }
- };
+ // Comparison routine used when sorting into a string table.
+
+ typedef typename String_set_type::iterator Stringpool_sort_info;
struct Stringpool_sort_comparison
{
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