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Diffstat (limited to 'binutils-2.25/gold/merge.cc')
| -rw-r--r-- | binutils-2.25/gold/merge.cc | 762 |
1 files changed, 762 insertions, 0 deletions
diff --git a/binutils-2.25/gold/merge.cc b/binutils-2.25/gold/merge.cc new file mode 100644 index 00000000..f370c9cb --- /dev/null +++ b/binutils-2.25/gold/merge.cc @@ -0,0 +1,762 @@ +// merge.cc -- handle section merging for gold + +// Copyright 2006, 2007, 2008, 2009, 2010, 2011 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 <cstdlib> +#include <algorithm> + +#include "merge.h" +#include "compressed_output.h" + +namespace gold +{ + +// Class Object_merge_map. + +// Destructor. + +Object_merge_map::~Object_merge_map() +{ + for (Section_merge_maps::iterator p = this->section_merge_maps_.begin(); + p != this->section_merge_maps_.end(); + ++p) + delete p->second; +} + +// Get the Input_merge_map to use for an input section, or NULL. + +Object_merge_map::Input_merge_map* +Object_merge_map::get_input_merge_map(unsigned int shndx) +{ + gold_assert(shndx != -1U); + if (shndx == this->first_shnum_) + return &this->first_map_; + if (shndx == this->second_shnum_) + return &this->second_map_; + Section_merge_maps::const_iterator p = this->section_merge_maps_.find(shndx); + if (p != this->section_merge_maps_.end()) + return p->second; + return NULL; +} + +// Get or create the Input_merge_map to use for an input section. + +Object_merge_map::Input_merge_map* +Object_merge_map::get_or_make_input_merge_map(const Merge_map* merge_map, + unsigned int shndx) +{ + Input_merge_map* map = this->get_input_merge_map(shndx); + if (map != NULL) + { + // For a given input section in a given object, every mapping + // must be done with the same Merge_map. + gold_assert(map->merge_map == merge_map); + return map; + } + + // We need to create a new entry. + if (this->first_shnum_ == -1U) + { + this->first_shnum_ = shndx; + this->first_map_.merge_map = merge_map; + return &this->first_map_; + } + if (this->second_shnum_ == -1U) + { + this->second_shnum_ = shndx; + this->second_map_.merge_map = merge_map; + return &this->second_map_; + } + + Input_merge_map* new_map = new Input_merge_map; + new_map->merge_map = merge_map; + this->section_merge_maps_[shndx] = new_map; + return new_map; +} + +// Add a mapping. + +void +Object_merge_map::add_mapping(const Merge_map* merge_map, unsigned int shndx, + section_offset_type input_offset, + section_size_type length, + section_offset_type output_offset) +{ + Input_merge_map* map = this->get_or_make_input_merge_map(merge_map, shndx); + + // Try to merge the new entry in the last one we saw. + if (!map->entries.empty()) + { + Input_merge_entry& entry(map->entries.back()); + + // Use section_size_type to avoid signed/unsigned warnings. + section_size_type input_offset_u = input_offset; + section_size_type output_offset_u = output_offset; + + // If this entry is not in order, we need to sort the vector + // before looking anything up. + if (input_offset_u < entry.input_offset + entry.length) + { + gold_assert(input_offset < entry.input_offset); + gold_assert(input_offset_u + length + <= static_cast<section_size_type>(entry.input_offset)); + map->sorted = false; + } + else if (entry.input_offset + entry.length == input_offset_u + && (output_offset == -1 + ? entry.output_offset == -1 + : entry.output_offset + entry.length == output_offset_u)) + { + entry.length += length; + return; + } + } + + Input_merge_entry entry; + entry.input_offset = input_offset; + entry.length = length; + entry.output_offset = output_offset; + map->entries.push_back(entry); +} + +// Get the output offset for an input address. + +bool +Object_merge_map::get_output_offset(const Merge_map* merge_map, + unsigned int shndx, + section_offset_type input_offset, + section_offset_type* output_offset) +{ + Input_merge_map* map = this->get_input_merge_map(shndx); + if (map == NULL + || (merge_map != NULL && map->merge_map != merge_map)) + return false; + + if (!map->sorted) + { + std::sort(map->entries.begin(), map->entries.end(), + Input_merge_compare()); + map->sorted = true; + } + + Input_merge_entry entry; + entry.input_offset = input_offset; + std::vector<Input_merge_entry>::const_iterator p = + std::lower_bound(map->entries.begin(), map->entries.end(), + entry, Input_merge_compare()); + if (p == map->entries.end() || p->input_offset > input_offset) + { + if (p == map->entries.begin()) + return false; + --p; + gold_assert(p->input_offset <= input_offset); + } + + if (input_offset - p->input_offset + >= static_cast<section_offset_type>(p->length)) + return false; + + *output_offset = p->output_offset; + if (*output_offset != -1) + *output_offset += (input_offset - p->input_offset); + return true; +} + +// Return whether this is the merge map for section SHNDX. + +inline bool +Object_merge_map::is_merge_section_for(const Merge_map* merge_map, + unsigned int shndx) +{ + Input_merge_map* map = this->get_input_merge_map(shndx); + return map != NULL && map->merge_map == merge_map; +} + +// Initialize a mapping from input offsets to output addresses. + +template<int size> +void +Object_merge_map::initialize_input_to_output_map( + unsigned int shndx, + typename elfcpp::Elf_types<size>::Elf_Addr starting_address, + Unordered_map<section_offset_type, + typename elfcpp::Elf_types<size>::Elf_Addr>* initialize_map) +{ + Input_merge_map* map = this->get_input_merge_map(shndx); + gold_assert(map != NULL); + + gold_assert(initialize_map->empty()); + // We know how many entries we are going to add. + // reserve_unordered_map takes an expected count of buckets, not a + // count of elements, so double it to try to reduce collisions. + reserve_unordered_map(initialize_map, map->entries.size() * 2); + + for (Input_merge_map::Entries::const_iterator p = map->entries.begin(); + p != map->entries.end(); + ++p) + { + section_offset_type output_offset = p->output_offset; + if (output_offset != -1) + output_offset += starting_address; + else + { + // If we see a relocation against an address we have chosen + // to discard, we relocate to zero. FIXME: We could also + // issue a warning in this case; that would require + // reporting this somehow and checking it in the routines in + // reloc.h. + output_offset = 0; + } + initialize_map->insert(std::make_pair(p->input_offset, output_offset)); + } +} + +// Class Merge_map. + +// Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in input +// section SHNDX in object OBJECT to an OUTPUT_OFFSET in merged data +// in an output section. + +void +Merge_map::add_mapping(Relobj* object, unsigned int shndx, + section_offset_type offset, section_size_type length, + section_offset_type output_offset) +{ + gold_assert(object != NULL); + Object_merge_map* object_merge_map = object->merge_map(); + if (object_merge_map == NULL) + { + object_merge_map = new Object_merge_map(); + object->set_merge_map(object_merge_map); + } + + object_merge_map->add_mapping(this, shndx, offset, length, output_offset); +} + +// Return the output offset for an input address. The input address +// is at offset OFFSET in section SHNDX in OBJECT. This sets +// *OUTPUT_OFFSET to the offset in the merged data in the output +// section. This returns true if the mapping is known, false +// otherwise. + +bool +Merge_map::get_output_offset(const Relobj* object, unsigned int shndx, + section_offset_type offset, + section_offset_type* output_offset) const +{ + Object_merge_map* object_merge_map = object->merge_map(); + if (object_merge_map == NULL) + return false; + return object_merge_map->get_output_offset(this, shndx, offset, + output_offset); +} + +// Return whether this is the merge section for SHNDX in OBJECT. + +bool +Merge_map::is_merge_section_for(const Relobj* object, unsigned int shndx) const +{ + Object_merge_map* object_merge_map = object->merge_map(); + if (object_merge_map == NULL) + return false; + return object_merge_map->is_merge_section_for(this, shndx); +} + +// Class Output_merge_base. + +// Return the output offset for an input offset. The input address is +// at offset OFFSET in section SHNDX in OBJECT. If we know the +// offset, set *POUTPUT and return true. Otherwise return false. + +bool +Output_merge_base::do_output_offset(const Relobj* object, + unsigned int shndx, + section_offset_type offset, + section_offset_type* poutput) const +{ + return this->merge_map_.get_output_offset(object, shndx, offset, poutput); +} + +// Return whether this is the merge section for SHNDX in OBJECT. + +bool +Output_merge_base::do_is_merge_section_for(const Relobj* object, + unsigned int shndx) const +{ + return this->merge_map_.is_merge_section_for(object, shndx); +} + +// Record a merged input section for script processing. + +void +Output_merge_base::record_input_section(Relobj* relobj, unsigned int shndx) +{ + gold_assert(this->keeps_input_sections_ && relobj != NULL); + // If this is the first input section, record it. We need do this because + // this->input_sections_ is unordered. + if (this->first_relobj_ == NULL) + { + this->first_relobj_ = relobj; + this->first_shndx_ = shndx; + } + + std::pair<Input_sections::iterator, bool> result = + this->input_sections_.insert(Section_id(relobj, shndx)); + // We should insert a merge section once only. + gold_assert(result.second); +} + +// Class Output_merge_data. + +// Compute the hash code for a fixed-size constant. + +size_t +Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const +{ + const unsigned char* p = this->pomd_->constant(k); + section_size_type entsize = + convert_to_section_size_type(this->pomd_->entsize()); + + // Fowler/Noll/Vo (FNV) hash (type FNV-1a). + if (sizeof(size_t) == 8) + { + size_t result = static_cast<size_t>(14695981039346656037ULL); + for (section_size_type i = 0; i < entsize; ++i) + { + result &= (size_t) *p++; + result *= 1099511628211ULL; + } + return result; + } + else + { + size_t result = 2166136261UL; + for (section_size_type i = 0; i < entsize; ++i) + { + result ^= (size_t) *p++; + result *= 16777619UL; + } + return result; + } +} + +// Return whether one hash table key equals another. + +bool +Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1, + Merge_data_key k2) const +{ + const unsigned char* p1 = this->pomd_->constant(k1); + const unsigned char* p2 = this->pomd_->constant(k2); + return memcmp(p1, p2, this->pomd_->entsize()) == 0; +} + +// Add a constant to the end of the section contents. + +void +Output_merge_data::add_constant(const unsigned char* p) +{ + section_size_type entsize = convert_to_section_size_type(this->entsize()); + section_size_type addralign = + convert_to_section_size_type(this->addralign()); + section_size_type addsize = std::max(entsize, addralign); + if (this->len_ + addsize > this->alc_) + { + if (this->alc_ == 0) + this->alc_ = 128 * addsize; + else + this->alc_ *= 2; + this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_)); + if (this->p_ == NULL) + gold_nomem(); + } + + memcpy(this->p_ + this->len_, p, entsize); + if (addsize > entsize) + memset(this->p_ + this->len_ + entsize, 0, addsize - entsize); + this->len_ += addsize; +} + +// Add the input section SHNDX in OBJECT to a merged output section +// which holds fixed length constants. Return whether we were able to +// handle the section; if not, it will be linked as usual without +// constant merging. + +bool +Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx) +{ + section_size_type len; + bool is_new; + const unsigned char* p = object->decompressed_section_contents(shndx, &len, + &is_new); + + section_size_type entsize = convert_to_section_size_type(this->entsize()); + + if (len % entsize != 0) + { + if (is_new) + delete[] p; + return false; + } + + this->input_count_ += len / entsize; + + for (section_size_type i = 0; i < len; i += entsize, p += entsize) + { + // Add the constant to the section contents. If we find that it + // is already in the hash table, we will remove it again. + Merge_data_key k = this->len_; + this->add_constant(p); + + std::pair<Merge_data_hashtable::iterator, bool> ins = + this->hashtable_.insert(k); + + if (!ins.second) + { + // Key was already present. Remove the copy we just added. + this->len_ -= entsize; + k = *ins.first; + } + + // Record the offset of this constant in the output section. + this->add_mapping(object, shndx, i, entsize, k); + } + + // For script processing, we keep the input sections. + if (this->keeps_input_sections()) + record_input_section(object, shndx); + + if (is_new) + delete[] p; + + return true; +} + +// Set the final data size in a merged output section with fixed size +// constants. + +void +Output_merge_data::set_final_data_size() +{ + // Release the memory we don't need. + this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_)); + // An Output_merge_data object may be empty and realloc is allowed + // to return a NULL pointer in this case. An Output_merge_data is empty + // if all its input sections have sizes that are not multiples of entsize. + gold_assert(this->p_ != NULL || this->len_ == 0); + this->set_data_size(this->len_); +} + +// Write the data of a merged output section with fixed size constants +// to the file. + +void +Output_merge_data::do_write(Output_file* of) +{ + of->write(this->offset(), this->p_, this->len_); +} + +// Write the data to a buffer. + +void +Output_merge_data::do_write_to_buffer(unsigned char* buffer) +{ + memcpy(buffer, this->p_, this->len_); +} + +// Print merge stats to stderr. + +void +Output_merge_data::do_print_merge_stats(const char* section_name) +{ + fprintf(stderr, + _("%s: %s merged constants size: %lu; input: %zu; output: %zu\n"), + program_name, section_name, + static_cast<unsigned long>(this->entsize()), + this->input_count_, this->hashtable_.size()); +} + +// Class Output_merge_string. + +// Add an input section to a merged string section. + +template<typename Char_type> +bool +Output_merge_string<Char_type>::do_add_input_section(Relobj* object, + unsigned int shndx) +{ + section_size_type sec_len; + bool is_new; + const unsigned char* pdata = object->decompressed_section_contents(shndx, + &sec_len, + &is_new); + + const Char_type* p = reinterpret_cast<const Char_type*>(pdata); + const Char_type* pend = p + sec_len / sizeof(Char_type); + const Char_type* pend0 = pend; + + if (sec_len % sizeof(Char_type) != 0) + { + object->error(_("mergeable string section length not multiple of " + "character size")); + if (is_new) + delete[] pdata; + return false; + } + + if (pend[-1] != 0) + { + gold_warning(_("%s: last entry in mergeable string section '%s' " + "not null terminated"), + object->name().c_str(), + object->section_name(shndx).c_str()); + // Find the end of the last NULL-terminated string in the buffer. + while (pend0 > p && pend0[-1] != 0) + --pend0; + } + + Merged_strings_list* merged_strings_list = + new Merged_strings_list(object, shndx); + this->merged_strings_lists_.push_back(merged_strings_list); + Merged_strings& merged_strings = merged_strings_list->merged_strings; + + // Count the number of non-null strings in the section and size the list. + size_t count = 0; + const Char_type* pt = p; + while (pt < pend0) + { + size_t len = string_length(pt); + if (len != 0) + ++count; + pt += len + 1; + } + if (pend0 < pend) + ++count; + merged_strings.reserve(count + 1); + + // The index I is in bytes, not characters. + section_size_type i = 0; + + // We assume here that the beginning of the section is correctly + // aligned, so each string within the section must retain the same + // modulo. + uintptr_t init_align_modulo = (reinterpret_cast<uintptr_t>(pdata) + & (this->addralign() - 1)); + bool has_misaligned_strings = false; + + while (p < pend0) + { + size_t len = string_length(p); + + // Within merge input section each string must be aligned. + if (len != 0 + && ((reinterpret_cast<uintptr_t>(p) & (this->addralign() - 1)) + != init_align_modulo)) + has_misaligned_strings = true; + + Stringpool::Key key; + this->stringpool_.add_with_length(p, len, true, &key); + + merged_strings.push_back(Merged_string(i, key)); + p += len + 1; + i += (len + 1) * sizeof(Char_type); + } + if (p < pend) + { + size_t len = pend - p; + + Stringpool::Key key; + this->stringpool_.add_with_length(p, len, true, &key); + + merged_strings.push_back(Merged_string(i, key)); + + i += (len + 1) * sizeof(Char_type); + } + + // Record the last offset in the input section so that we can + // compute the length of the last string. + merged_strings.push_back(Merged_string(i, 0)); + + this->input_count_ += count; + this->input_size_ += i; + + if (has_misaligned_strings) + gold_warning(_("%s: section %s contains incorrectly aligned strings;" + " the alignment of those strings won't be preserved"), + object->name().c_str(), + object->section_name(shndx).c_str()); + + // For script processing, we keep the input sections. + if (this->keeps_input_sections()) + record_input_section(object, shndx); + + if (is_new) + delete[] pdata; + + return true; +} + +// Finalize the mappings from the input sections to the output +// section, and return the final data size. + +template<typename Char_type> +section_size_type +Output_merge_string<Char_type>::finalize_merged_data() +{ + this->stringpool_.set_string_offsets(); + + for (typename Merged_strings_lists::const_iterator l = + this->merged_strings_lists_.begin(); + l != this->merged_strings_lists_.end(); + ++l) + { + section_offset_type last_input_offset = 0; + section_offset_type last_output_offset = 0; + for (typename Merged_strings::const_iterator p = + (*l)->merged_strings.begin(); + p != (*l)->merged_strings.end(); + ++p) + { + section_size_type length = p->offset - last_input_offset; + if (length > 0) + this->add_mapping((*l)->object, (*l)->shndx, last_input_offset, + length, last_output_offset); + last_input_offset = p->offset; + if (p->stringpool_key != 0) + last_output_offset = + this->stringpool_.get_offset_from_key(p->stringpool_key); + } + delete *l; + } + + // Save some memory. This also ensures that this function will work + // if called twice, as may happen if Layout::set_segment_offsets + // finds a better alignment. + this->merged_strings_lists_.clear(); + + return this->stringpool_.get_strtab_size(); +} + +template<typename Char_type> +void +Output_merge_string<Char_type>::set_final_data_size() +{ + const off_t final_data_size = this->finalize_merged_data(); + this->set_data_size(final_data_size); +} + +// Write out a merged string section. + +template<typename Char_type> +void +Output_merge_string<Char_type>::do_write(Output_file* of) +{ + this->stringpool_.write(of, this->offset()); +} + +// Write a merged string section to a buffer. + +template<typename Char_type> +void +Output_merge_string<Char_type>::do_write_to_buffer(unsigned char* buffer) +{ + this->stringpool_.write_to_buffer(buffer, this->data_size()); +} + +// Return the name of the types of string to use with +// do_print_merge_stats. + +template<typename Char_type> +const char* +Output_merge_string<Char_type>::string_name() +{ + gold_unreachable(); + return NULL; +} + +template<> +const char* +Output_merge_string<char>::string_name() +{ + return "strings"; +} + +template<> +const char* +Output_merge_string<uint16_t>::string_name() +{ + return "16-bit strings"; +} + +template<> +const char* +Output_merge_string<uint32_t>::string_name() +{ + return "32-bit strings"; +} + +// Print merge stats to stderr. + +template<typename Char_type> +void +Output_merge_string<Char_type>::do_print_merge_stats(const char* section_name) +{ + char buf[200]; + snprintf(buf, sizeof buf, "%s merged %s", section_name, this->string_name()); + fprintf(stderr, _("%s: %s input bytes: %zu\n"), + program_name, buf, this->input_size_); + fprintf(stderr, _("%s: %s input strings: %zu\n"), + program_name, buf, this->input_count_); + this->stringpool_.print_stats(buf); +} + +// Instantiate the templates we need. + +template +class Output_merge_string<char>; + +template +class Output_merge_string<uint16_t>; + +template +class Output_merge_string<uint32_t>; + +#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) +template +void +Object_merge_map::initialize_input_to_output_map<32>( + unsigned int shndx, + elfcpp::Elf_types<32>::Elf_Addr starting_address, + Unordered_map<section_offset_type, elfcpp::Elf_types<32>::Elf_Addr>*); +#endif + +#if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) +template +void +Object_merge_map::initialize_input_to_output_map<64>( + unsigned int shndx, + elfcpp::Elf_types<64>::Elf_Addr starting_address, + Unordered_map<section_offset_type, elfcpp::Elf_types<64>::Elf_Addr>*); +#endif + +} // End namespace gold. |