| // stringpool.cc -- a string pool for gold |
| |
| #include "gold.h" |
| |
| #include <cassert> |
| #include <cstring> |
| #include <algorithm> |
| #include <vector> |
| |
| #include "output.h" |
| #include "stringpool.h" |
| |
| namespace gold |
| { |
| |
| Stringpool::Stringpool() |
| : string_set_(), strings_(), strtab_size_(0), next_index_(1) |
| { |
| } |
| |
| Stringpool::~Stringpool() |
| { |
| for (std::list<Stringdata*>::iterator p = this->strings_.begin(); |
| p != this->strings_.end(); |
| ++p) |
| delete[] reinterpret_cast<char*>(*p); |
| } |
| |
| // Hash function. |
| |
| size_t |
| Stringpool::Stringpool_hash::operator()(const 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') |
| { |
| result &= (size_t) *s++; |
| result *= 1099511628211ULL; |
| } |
| return result; |
| } |
| else |
| { |
| size_t result = 2166136261UL; |
| while (*s != '\0') |
| { |
| result ^= (size_t) *s++; |
| 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. |
| |
| const char* |
| Stringpool::add_string(const char* s, Key* pkey) |
| { |
| // The size we allocate for a new Stringdata. |
| const size_t buffer_size = 1000; |
| // The amount we multiply the Stringdata index when calculating the |
| // key. |
| const size_t key_mult = 1024; |
| assert(key_mult >= buffer_size); |
| |
| size_t len = strlen(s); |
| |
| size_t alc; |
| bool front = true; |
| if (len >= buffer_size) |
| { |
| alc = sizeof(Stringdata) + len; |
| front = false; |
| } |
| else if (this->strings_.empty()) |
| alc = sizeof(Stringdata) + buffer_size; |
| else |
| { |
| Stringdata *psd = this->strings_.front(); |
| if (len >= psd->alc - psd->len) |
| alc = sizeof(Stringdata) + buffer_size; |
| else |
| { |
| char* ret = psd->data + psd->len; |
| memcpy(ret, s, len + 1); |
| |
| if (pkey != NULL) |
| *pkey = psd->index * key_mult + psd->len; |
| |
| psd->len += len + 1; |
| |
| return ret; |
| } |
| } |
| |
| Stringdata *psd = reinterpret_cast<Stringdata*>(new char[alc]); |
| psd->alc = alc - sizeof(Stringdata); |
| memcpy(psd->data, s, len + 1); |
| psd->len = len + 1; |
| 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; |
| } |
| |
| // Add a string to a string pool. |
| |
| const char* |
| Stringpool::add(const 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 |
| // 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. |
| |
| String_set_type::const_iterator p = this->string_set_.find(s); |
| if (p != this->string_set_.end()) |
| { |
| if (pkey != NULL) |
| *pkey = p->second.first; |
| return p->first; |
| } |
| |
| Key k; |
| const char* ret = this->add_string(s, &k); |
| |
| const off_t ozero = 0; |
| std::pair<const char*, Val> element(ret, std::make_pair(k, ozero)); |
| std::pair<String_set_type::iterator, bool> ins = |
| this->string_set_.insert(element); |
| assert(ins.second); |
| |
| if (pkey != NULL) |
| *pkey = k; |
| |
| return ret; |
| } |
| |
| // Add a prefix of a string to a string pool. |
| |
| const char* |
| Stringpool::add(const 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, pkey); |
| } |
| |
| const char* |
| Stringpool::find(const char* s, Key* pkey) const |
| { |
| 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; |
| } |
| |
| // Comparison routine used when sorting into an ELF strtab. We want |
| // to sort this so that when one string is a suffix of another, we |
| // always see the shorter string immediately after the longer string. |
| // For example, we want to see these strings in this order: |
| // abcd |
| // cd |
| // d |
| // When strings are not suffixes, we don't care what order they are |
| // 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. |
| |
| 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) |
| { |
| if (*p1 != *p2) |
| return *p1 > *p2; |
| } |
| return len1 > len2; |
| } |
| |
| // Return whether s1 is a suffix of s2. |
| |
| bool |
| Stringpool::is_suffix(const char* s1, const char* s2) |
| { |
| size_t len1 = strlen(s1); |
| size_t len2 = strlen(s2); |
| if (len1 > len2) |
| return false; |
| return strcmp(s1, s2 + len2 - len1) == 0; |
| } |
| |
| // Turn the stringpool into an ELF strtab: determine the offsets of |
| // each string in the table. |
| |
| void |
| Stringpool::set_string_offsets() |
| { |
| size_t count = this->string_set_.size(); |
| |
| std::vector<String_set_type::iterator> v; |
| v.reserve(count); |
| |
| for (String_set_type::iterator p = this->string_set_.begin(); |
| p != this->string_set_.end(); |
| ++p) |
| v.push_back(p); |
| |
| std::sort(v.begin(), v.end(), Stringpool_sort_comparison()); |
| |
| // Offset 0 is reserved for the empty string. |
| off_t offset = 1; |
| for (size_t i = 0; i < count; ++i) |
| { |
| if (v[i]->first[0] == '\0') |
| v[i]->second.second = 0; |
| else if (i > 0 && Stringpool::is_suffix(v[i]->first, v[i - 1]->first)) |
| v[i]->second.second = (v[i - 1]->second.second |
| + strlen(v[i - 1]->first) |
| - strlen(v[i]->first)); |
| else |
| { |
| v[i]->second.second = offset; |
| offset += strlen(v[i]->first) + 1; |
| } |
| } |
| |
| 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 |
| { |
| String_set_type::const_iterator p = this->string_set_.find(s); |
| if (p != this->string_set_.end()) |
| return p->second.second; |
| abort(); |
| } |
| |
| // Write the ELF strtab into the output file at the specified offset. |
| |
| void |
| Stringpool::write(Output_file* of, off_t offset) |
| { |
| 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(); |
| p != this->string_set_.end(); |
| ++p) |
| strcpy(view + p->second.second, p->first); |
| of->write_output_view(offset, this->strtab_size_, viewu); |
| } |
| |
| } // End namespace gold. |