// stringpool.cc -- a string pool for gold
+// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
#include "gold.h"
-#include <cassert>
#include <cstring>
#include <algorithm>
#include <vector>
#include "output.h"
+#include "parameters.h"
#include "stringpool.h"
namespace gold
{
-Stringpool::Stringpool()
- : string_set_(), strings_(), strtab_size_(0)
+template<typename Stringpool_char>
+Stringpool_template<Stringpool_char>::Stringpool_template()
+ : string_set_(), strings_(), strtab_size_(0), next_index_(1),
+ zero_null_(true)
{
}
-Stringpool::~Stringpool()
+template<typename Stringpool_char>
+Stringpool_template<Stringpool_char>::~Stringpool_template()
{
- for (std::list<Stringdata*>::iterator p = this->strings_.begin();
+ for (typename std::list<Stringdata*>::iterator p = this->strings_.begin();
p != this->strings_.end();
++p)
delete[] reinterpret_cast<char*>(*p);
}
+// Return the length of a string of arbitrary character type.
+
+template<typename Stringpool_char>
+size_t
+Stringpool_template<Stringpool_char>::string_length(const Stringpool_char* p)
+{
+ size_t len = 0;
+ for (; *p != 0; ++p)
+ ++len;
+ return len;
+}
+
+// Specialize string_length for char. Maybe we could just use
+// std::char_traits<>::length?
+
+template<>
+inline size_t
+Stringpool_template<char>::string_length(const char* p)
+{
+ return strlen(p);
+}
+
+// Equality comparison function.
+
+template<typename Stringpool_char>
+bool
+Stringpool_template<Stringpool_char>::Stringpool_eq::operator()(
+ const Stringpool_char* s1,
+ const Stringpool_char* s2) const
+{
+ while (*s1 != 0)
+ if (*s1++ != *s2++)
+ return false;
+ return *s2 == 0;
+}
+
+// Specialize equality comparison for char.
+
+template<>
+bool
+Stringpool_template<char>::Stringpool_eq::operator()(const char* s1,
+ const char* s2) const
+{
+ return strcmp(s1, s2) == 0;
+}
+
// Hash function.
+template<typename Stringpool_char>
size_t
-Stringpool::Stringpool_hash::operator()(const char* s) const
+Stringpool_template<Stringpool_char>::Stringpool_hash::operator()(
+ const Stringpool_char* s) const
{
// Fowler/Noll/Vo (FNV) hash (type FNV-1a).
if (sizeof(size_t) == 8)
{
size_t result = static_cast<size_t>(14695981039346656037ULL);
- while (*s != '\0')
+ while (*s != 0)
{
- result &= (size_t) *s++;
- result *= 1099511628211ULL;
+ 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;
}
return result;
}
else
{
size_t result = 2166136261UL;
- while (*s != '\0')
+ while (*s != 0)
{
- result ^= (size_t) *s++;
- result *= 16777619UL;
+ 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;
}
return result;
}
}
// Add a string to the list of canonical strings. Return a pointer to
-// the canonical string.
+// the canonical string. If PKEY is not NULL, set *PKEY to the key.
-const char*
-Stringpool::add_string(const char* s)
+template<typename Stringpool_char>
+const Stringpool_char*
+Stringpool_template<Stringpool_char>::add_string(const Stringpool_char* s,
+ Key* pkey)
{
+ // We are in trouble if we've already computed the string offsets.
+ gold_assert(this->strtab_size_ == 0);
+
+ // The size we allocate for a new Stringdata.
const size_t buffer_size = 1000;
- size_t len = strlen(s);
+ // The amount we multiply the Stringdata index when calculating the
+ // key.
+ const size_t key_mult = 1024;
+ gold_assert(key_mult >= buffer_size);
+
+ size_t len = (string_length(s) + 1) * sizeof(Stringpool_char);
size_t alc;
bool front = true;
- if (len >= buffer_size)
+ if (len > buffer_size)
{
alc = sizeof(Stringdata) + len;
front = false;
else
{
Stringdata *psd = this->strings_.front();
- if (len >= psd->alc - psd->len)
+ if (len > psd->alc - psd->len)
alc = sizeof(Stringdata) + buffer_size;
else
{
char* ret = psd->data + psd->len;
- memcpy(ret, s, len + 1);
- psd->len += len + 1;
- return ret;
+ memcpy(ret, s, len);
+
+ if (pkey != NULL)
+ *pkey = psd->index * key_mult + psd->len;
+
+ psd->len += len;
+
+ return reinterpret_cast<const Stringpool_char*>(ret);
}
}
Stringdata *psd = reinterpret_cast<Stringdata*>(new char[alc]);
psd->alc = alc - sizeof(Stringdata);
- memcpy(psd->data, s, len + 1);
- psd->len = len + 1;
+ memcpy(psd->data, s, len);
+ psd->len = len;
+ psd->index = this->next_index_;
+ ++this->next_index_;
+
+ if (pkey != NULL)
+ *pkey = psd->index * key_mult;
+
if (front)
this->strings_.push_front(psd);
else
this->strings_.push_back(psd);
- return psd->data;
+
+ return reinterpret_cast<const Stringpool_char*>(psd->data);
}
// Add a string to a string pool.
-const char*
-Stringpool::add(const char* s)
+template<typename Stringpool_char>
+const Stringpool_char*
+Stringpool_template<Stringpool_char>::add(const Stringpool_char* s, 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
// unordered_map, so this should be replaced with custom code to do
// what we need, which is to return the empty slot.
- String_set_type::const_iterator p = this->string_set_.find(s);
+ typename String_set_type::const_iterator p = this->string_set_.find(s);
if (p != this->string_set_.end())
- return p->first;
+ {
+ if (pkey != NULL)
+ *pkey = p->second.first;
+ return p->first;
+ }
+
+ Key k;
+ const Stringpool_char* ret = this->add_string(s, &k);
+
+ 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);
+
+ if (pkey != NULL)
+ *pkey = k;
- const char* ret = this->add_string(s);
- std::pair<const char*, off_t> val(ret, 0);
- std::pair<String_set_type::iterator, bool> ins =
- this->string_set_.insert(val);
- assert(ins.second);
return ret;
}
// Add a prefix of a string to a string pool.
-const char*
-Stringpool::add(const char* s, size_t len)
+template<typename Stringpool_char>
+const Stringpool_char*
+Stringpool_template<Stringpool_char>::add(const Stringpool_char* s, size_t len,
+ Key* pkey)
{
// FIXME: This implementation should be rewritten when we rewrite
// the hash table to avoid copying.
- std::string st(s, len);
- return this->add(st);
+ std::basic_string<Stringpool_char> st(s, len);
+ return this->add(st, pkey);
}
-const char*
-Stringpool::find(const char* s) const
+template<typename Stringpool_char>
+const Stringpool_char*
+Stringpool_template<Stringpool_char>::find(const Stringpool_char* s,
+ Key* pkey) const
{
- String_set_type::const_iterator p = this->string_set_.find(s);
+ typename String_set_type::const_iterator p = this->string_set_.find(s);
if (p == this->string_set_.end())
return NULL;
+
+ if (pkey != NULL)
+ *pkey = p->second.first;
+
return p->first;
}
// in, but we need to ensure that suffixes wind up next to each other.
// So we do a reversed lexicographic sort on the reversed string.
+template<typename Stringpool_char>
bool
-Stringpool::Stringpool_sort_comparison::operator()(
- String_set_type::iterator it1,
- String_set_type::iterator it2) const
-{
- const char* s1 = it1->first;
- const char* s2 = it2->first;
- int len1 = strlen(s1);
- int len2 = strlen(s2);
- int minlen = len1 < len2 ? len1 : len2;
- const char* p1 = s1 + len1 - 1;
- const char* p2 = s2 + len2 - 1;
- for (int i = minlen - 1; i >= 0; --i, --p1, --p2)
+Stringpool_template<Stringpool_char>::Stringpool_sort_comparison::operator()(
+ 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 size_t minlen = len1 < len2 ? len1 : len2;
+ const Stringpool_char* p1 = s1 + len1 - 1;
+ const Stringpool_char* p2 = s2 + len2 - 1;
+ for (size_t i = minlen; i > 0; --i, --p1, --p2)
{
if (*p1 != *p2)
return *p1 > *p2;
// Return whether s1 is a suffix of s2.
+template<typename Stringpool_char>
bool
-Stringpool::is_suffix(const char* s1, const char* s2)
+Stringpool_template<Stringpool_char>::is_suffix(const Stringpool_char* s1,
+ size_t len1,
+ const Stringpool_char* s2,
+ size_t len2)
{
- size_t len1 = strlen(s1);
- size_t len2 = strlen(s2);
if (len1 > len2)
return false;
- return strcmp(s1, s2 + len2 - len1) == 0;
+ return memcmp(s1, s2 + len2 - len1, len1 * sizeof(Stringpool_char)) == 0;
}
// Turn the stringpool into an ELF strtab: determine the offsets of
// each string in the table.
+template<typename Stringpool_char>
void
-Stringpool::set_string_offsets()
+Stringpool_template<Stringpool_char>::set_string_offsets()
{
- size_t count = this->string_set_.size();
-
- std::vector<String_set_type::iterator> v;
- v.reserve(count);
+ if (this->strtab_size_ != 0)
+ {
+ // We've already computed the offsets.
+ return;
+ }
- for (String_set_type::iterator p = this->string_set_.begin();
- p != this->string_set_.end();
- ++p)
- v.push_back(p);
+ const size_t charsize = sizeof(Stringpool_char);
- std::sort(v.begin(), v.end(), Stringpool_sort_comparison());
+ // Offset 0 may be reserved for the empty string.
+ off_t offset = this->zero_null_ ? charsize : 0;
- // Offset 0 is reserved for the empty string.
- off_t offset = 1;
- for (size_t i = 0; i < count; ++i)
+ // Sorting to find suffixes can take over 25% of the total CPU time
+ // used by the linker. Since it's merely an optimization to reduce
+ // the strtab size, and gives a relatively small benefit (it's
+ // typically rare for a symbol to be a suffix of another), we only
+ // take the time to sort when the user asks for heavy optimization.
+ if (parameters->optimization_level() < 2)
{
- if (v[i]->first[0] == '\0')
- v[i]->second = 0;
- else if (i > 0 && Stringpool::is_suffix(v[i]->first, v[i - 1]->first))
- v[i]->second = (v[i - 1]->second
- + strlen(v[i - 1]->first)
- - strlen(v[i]->first));
- else
- {
- v[i]->second = offset;
- offset += strlen(v[i]->first) + 1;
- }
+ for (typename String_set_type::iterator curr = this->string_set_.begin();
+ curr != this->string_set_.end();
+ curr++)
+ {
+ if (this->zero_null_ && curr->first[0] == 0)
+ curr->second.second = 0;
+ else
+ {
+ curr->second.second = offset;
+ offset += (string_length(curr->first) + 1) * charsize;
+ }
+ }
+ }
+ else
+ {
+ size_t count = this->string_set_.size();
+
+ std::vector<Stringpool_sort_info> v;
+ v.reserve(count);
+
+ 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)));
+
+ std::sort(v.begin(), v.end(), Stringpool_sort_comparison());
+
+ for (typename std::vector<Stringpool_sort_info>::iterator last = v.end(),
+ curr = v.begin();
+ curr != v.end();
+ last = curr++)
+ {
+ if (this->zero_null_ && curr->it->first[0] == 0)
+ curr->it->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));
+ else
+ {
+ curr->it->second.second = offset;
+ offset += (curr->string_length + 1) * charsize;
+ }
+ }
}
this->strtab_size_ = offset;
// Get the offset of a string in the ELF strtab. The string must
// exist.
+template<typename Stringpool_char>
off_t
-Stringpool::get_offset(const char* s) const
+Stringpool_template<Stringpool_char>::get_offset(const Stringpool_char* s)
+ const
{
- String_set_type::const_iterator p = this->string_set_.find(s);
+ gold_assert(this->strtab_size_ != 0);
+ typename String_set_type::const_iterator p = this->string_set_.find(s);
if (p != this->string_set_.end())
- return p->second;
- abort();
+ return p->second.second;
+ gold_unreachable();
}
// Write the ELF strtab into the output file at the specified offset.
+template<typename Stringpool_char>
void
-Stringpool::write(Output_file* of, off_t offset)
+Stringpool_template<Stringpool_char>::write(Output_file* of, off_t offset)
{
+ gold_assert(this->strtab_size_ != 0);
unsigned char* viewu = of->get_output_view(offset, this->strtab_size_);
char* view = reinterpret_cast<char*>(viewu);
- view[0] = '\0';
- for (String_set_type::const_iterator p = this->string_set_.begin();
+ if (this->zero_null_)
+ view[0] = '\0';
+ for (typename String_set_type::const_iterator p = this->string_set_.begin();
p != this->string_set_.end();
++p)
- strcpy(view + p->second, p->first);
+ memcpy(view + p->second.second, p->first,
+ (string_length(p->first) + 1) * sizeof(Stringpool_char));
of->write_output_view(offset, this->strtab_size_, viewu);
}
+// Instantiate the templates we need.
+
+template
+class Stringpool_template<char>;
+
+template
+class Stringpool_template<uint16_t>;
+
+template
+class Stringpool_template<uint32_t>;
+
} // End namespace gold.
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