// stringpool.cc -- a string pool for gold
+// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+
+// 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_(), key_to_offset_(), strings_(), strtab_size_(0),
+ zero_null_(true)
{
}
-Stringpool::~Stringpool()
+template<typename Stringpool_char>
+void
+Stringpool_template<Stringpool_char>::clear()
{
- 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);
+ this->strings_.clear();
+ this->key_to_offset_.clear();
+ this->string_set_.clear();
+}
+
+template<typename Stringpool_char>
+Stringpool_template<Stringpool_char>::~Stringpool_template()
+{
+ this->clear();
+}
+
+// Resize the internal hashtable with the expectation we'll get n new
+// elements. Note that the hashtable constructor takes a "number of
+// buckets you'd like," rather than "number of elements you'd like,"
+// but that's the best we can do.
+
+template<typename Stringpool_char>
+void
+Stringpool_template<Stringpool_char>::reserve(unsigned int n)
+{
+ this->key_to_offset_.reserve(n);
+
+#if defined(HAVE_TR1_UNORDERED_MAP)
+ // rehash() implementation is broken in gcc 4.0.3's stl
+ //this->string_set_.rehash(this->string_set_.size() + n);
+ //return;
+#elif defined(HAVE_EXT_HASH_MAP)
+ this->string_set_.resize(this->string_set_.size() + n);
+ return;
+#endif
+
+ // This is the generic "reserve" code, if no #ifdef above triggers.
+ String_set_type new_string_set(this->string_set_.size() + n);
+ new_string_set.insert(this->string_set_.begin(), this->string_set_.end());
+ this->string_set_.swap(new_string_set);
}
-// Hash function.
+// Return the length of a string of arbitrary character type.
+template<typename Stringpool_char>
size_t
-Stringpool::Stringpool_hash::operator()(const char* s) const
+Stringpool_template<Stringpool_char>::string_length(const Stringpool_char* p)
{
- // Fowler/Noll/Vo (FNV) hash (type FNV-1a).
- if (sizeof(size_t) == 8)
- {
- size_t result = static_cast<size_t>(14695981039346656037ULL);
- while (*s != '\0')
- {
- result &= (size_t) *s++;
- result *= 1099511628211ULL;
- }
- return result;
- }
- else
- {
- size_t result = 2166136261UL;
- while (*s != '\0')
- {
- result ^= (size_t) *s++;
- result *= 16777619UL;
- }
- return result;
- }
+ size_t len = 0;
+ for (; *p != 0; ++p)
+ ++len;
+ return len;
}
-// Add a string to the list of canonical strings. Return a pointer to
-// the canonical string.
+// Specialize string_length for char. Maybe we could just use
+// std::char_traits<>::length?
-const char*
-Stringpool::add_string(const char* s)
+template<>
+inline size_t
+Stringpool_template<char>::string_length(const char* p)
+{
+ return strlen(p);
+}
+
+// Compare two strings of arbitrary character type for equality.
+
+template<typename Stringpool_char>
+bool
+Stringpool_template<Stringpool_char>::string_equal(const Stringpool_char* s1,
+ const Stringpool_char* s2)
{
+ while (*s1 != 0)
+ if (*s1++ != *s2++)
+ return false;
+ return *s2 == 0;
+}
+
+// Specialize string_equal for char.
+
+template<>
+inline bool
+Stringpool_template<char>::string_equal(const char* s1, const char* s2)
+{
+ return strcmp(s1, s2) == 0;
+}
+
+// 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
+ && (h1.string == h2.string
+ || 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>::string_hash(const Stringpool_char* s,
+ size_t length)
+{
+ // This is the hash function used by the dynamic linker for
+ // DT_GNU_HASH entries. I compared this to a Fowler/Noll/Vo hash
+ // for a C++ program with 385,775 global symbols. This hash
+ // function was very slightly worse. However, it is much faster to
+ // compute. Overall wall clock time was a win.
+ const unsigned char* p = reinterpret_cast<const unsigned char*>(s);
+ size_t h = 5381;
+ for (size_t i = 0; i < length * sizeof(Stringpool_char); ++i)
+ h = h * 33 + *p++;
+ return h;
+}
+
+// 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)
+{
+ // 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);
+
+ // 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;
- 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 - sizeof(Stringpool_char));
+ memset(ret + len - sizeof(Stringpool_char), 0,
+ sizeof(Stringpool_char));
+
+ 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 - sizeof(Stringpool_char));
+ memset(psd->data + len - sizeof(Stringpool_char), 0,
+ sizeof(Stringpool_char));
+ psd->len = len;
+
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, bool copy,
+ Key* pkey)
+{
+ return this->add_with_length(s, string_length(s), copy, pkey);
+}
+
+template<typename Stringpool_char>
+const Stringpool_char*
+Stringpool_template<Stringpool_char>::add_with_length(const Stringpool_char* s,
+ size_t length,
+ 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;
+
+ const Key k = this->key_to_offset_.size();
- String_set_type::const_iterator p = this->string_set_.find(s);
+ if (!copy)
+ {
+ // When we don't need to copy the string, we can call insert
+ // directly.
+
+ std::pair<Hashkey, Hashval> element(Hashkey(s, length), k);
+
+ Insert_type ins = this->string_set_.insert(element);
+
+ 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->key_to_offset_.push_back(0);
+ }
+ else
+ {
+ gold_assert(k != p->second);
+ }
+
+ if (pkey != NULL)
+ *pkey = p->second;
+ return p->first.string;
+ }
+
+ // When we have to copy the string, we 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.
+
+ Hashkey hk(s, length);
+ typename String_set_type::const_iterator p = this->string_set_.find(hk);
if (p != this->string_set_.end())
- return p->first;
+ {
+ if (pkey != NULL)
+ *pkey = p->second;
+ return p->first.string;
+ }
- 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;
-}
+ this->key_to_offset_.push_back(0);
-// Add a prefix of a string to a string pool.
+ hk.string = this->add_string(s, length);
+ // The contents of the string stay the same, so we don't need to
+ // adjust hk.hash_code or hk.length.
-const char*
-Stringpool::add(const char* s, size_t len)
-{
- // 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::pair<Hashkey, Hashval> element(hk, k);
+
+ Insert_type ins = this->string_set_.insert(element);
+ gold_assert(ins.second);
+
+ if (pkey != NULL)
+ *pkey = k;
+ return hk.string;
}
-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);
+ Hashkey hk(s);
+ typename String_set_type::const_iterator p = this->string_set_.find(hk);
if (p == this->string_set_.end())
return NULL;
- return p->first;
+
+ if (pkey != NULL)
+ *pkey = p->second;
+
+ return p->first.string;
}
// Comparison routine used when sorting into an ELF strtab. We want
// 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 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;
+ 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.
+ section_offset_type 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->options().optimize() < 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++)
+ {
+ section_offset_type* poff = &this->key_to_offset_[curr->second];
+ if (this->zero_null_ && curr->first.string[0] == 0)
+ *poff = 0;
+ else
+ {
+ *poff = offset;
+ offset += (curr->first.length + 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));
+
+ std::sort(v.begin(), v.end(), Stringpool_sort_comparison());
+
+ section_offset_type last_offset = -1;
+ for (typename std::vector<Stringpool_sort_info>::iterator last = v.end(),
+ curr = v.begin();
+ curr != v.end();
+ last = curr++)
+ {
+ section_offset_type this_offset;
+ if (this->zero_null_ && (*curr)->first.string[0] == 0)
+ this_offset = 0;
+ else if (last != v.end()
+ && is_suffix((*curr)->first.string,
+ (*curr)->first.length,
+ (*last)->first.string,
+ (*last)->first.length))
+ this_offset = (last_offset
+ + (((*last)->first.length - (*curr)->first.length)
+ * charsize));
+ else
+ {
+ this_offset = offset;
+ offset += ((*curr)->first.length + 1) * charsize;
+ }
+ this->key_to_offset_[(*curr)->second] = this_offset;
+ last_offset = this_offset;
+ }
}
this->strtab_size_ = offset;
// Get the offset of a string in the ELF strtab. The string must
// exist.
-off_t
-Stringpool::get_offset(const char* s) const
+template<typename Stringpool_char>
+section_offset_type
+Stringpool_template<Stringpool_char>::get_offset(const Stringpool_char* s)
+ const
+{
+ return this->get_offset_with_length(s, string_length(s));
+}
+
+template<typename Stringpool_char>
+section_offset_type
+Stringpool_template<Stringpool_char>::get_offset_with_length(
+ const Stringpool_char* s,
+ size_t length) const
{
- String_set_type::const_iterator p = this->string_set_.find(s);
+ gold_assert(this->strtab_size_ != 0);
+ Hashkey hk(s, length);
+ typename String_set_type::const_iterator p = this->string_set_.find(hk);
if (p != this->string_set_.end())
- return p->second;
- abort();
+ return this->key_to_offset_[p->second];
+ gold_unreachable();
}
-// Write the ELF strtab into the output file at the specified offset.
+// Write the ELF strtab into the buffer.
+template<typename Stringpool_char>
void
-Stringpool::write(Output_file* of, off_t offset)
+Stringpool_template<Stringpool_char>::write_to_buffer(
+ unsigned char* buffer,
+ section_size_type bufsize)
{
- 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();
+ gold_assert(this->strtab_size_ != 0);
+ gold_assert(bufsize >= this->strtab_size_);
+ if (this->zero_null_)
+ buffer[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);
- of->write_output_view(offset, this->strtab_size_, viewu);
+ {
+ const int len = (p->first.length + 1) * sizeof(Stringpool_char);
+ const section_offset_type offset = this->key_to_offset_[p->second];
+ gold_assert(static_cast<section_size_type>(offset) + len
+ <= this->strtab_size_);
+ memcpy(buffer + offset, p->first.string, len);
+ }
}
+// Write the ELF strtab into the output file at the specified offset.
+
+template<typename Stringpool_char>
+void
+Stringpool_template<Stringpool_char>::write(Output_file* of, off_t offset)
+{
+ gold_assert(this->strtab_size_ != 0);
+ unsigned char* view = of->get_output_view(offset, this->strtab_size_);
+ this->write_to_buffer(view, this->strtab_size_);
+ of->write_output_view(offset, this->strtab_size_, view);
+}
+
+// Print statistical information to stderr. This is used for --stats.
+
+template<typename Stringpool_char>
+void
+Stringpool_template<Stringpool_char>::print_stats(const char* name) const
+{
+#if defined(HAVE_TR1_UNORDERED_MAP) || defined(HAVE_EXT_HASH_MAP)
+ fprintf(stderr, _("%s: %s entries: %zu; buckets: %zu\n"),
+ program_name, name, this->string_set_.size(),
+ this->string_set_.bucket_count());
+#else
+ fprintf(stderr, _("%s: %s entries: %zu\n"),
+ program_name, name, this->table_.size());
+#endif
+ fprintf(stderr, _("%s: %s Stringdata structures: %zu\n"),
+ program_name, name, this->strings_.size());
+}
+
+// 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.
projects / binutils.git / blobdiff