687 lines
19 KiB
C++
687 lines
19 KiB
C++
// merge.cc -- handle section merging for gold
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// Copyright (C) 2006-2015 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include <cstdlib>
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#include <algorithm>
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#include "merge.h"
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#include "compressed_output.h"
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namespace gold
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{
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// Class Object_merge_map.
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// Destructor.
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Object_merge_map::~Object_merge_map()
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{
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for (Section_merge_maps::iterator p = this->section_merge_maps_.begin();
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p != this->section_merge_maps_.end();
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++p)
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delete p->second;
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}
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// Get the Input_merge_map to use for an input section, or NULL.
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Object_merge_map::Input_merge_map*
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Object_merge_map::get_input_merge_map(unsigned int shndx)
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{
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gold_assert(shndx != -1U);
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if (shndx == this->first_shnum_)
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return &this->first_map_;
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if (shndx == this->second_shnum_)
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return &this->second_map_;
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Section_merge_maps::const_iterator p = this->section_merge_maps_.find(shndx);
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if (p != this->section_merge_maps_.end())
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return p->second;
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return NULL;
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}
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// Get or create the Input_merge_map to use for an input section.
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Object_merge_map::Input_merge_map*
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Object_merge_map::get_or_make_input_merge_map(
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const Output_section_data* output_data, unsigned int shndx) {
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Input_merge_map* map = this->get_input_merge_map(shndx);
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if (map != NULL)
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{
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// For a given input section in a given object, every mapping
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// must be done with the same Merge_map.
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gold_assert(map->output_data == output_data);
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return map;
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}
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// We need to create a new entry.
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if (this->first_shnum_ == -1U)
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{
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this->first_shnum_ = shndx;
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this->first_map_.output_data = output_data;
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return &this->first_map_;
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}
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if (this->second_shnum_ == -1U)
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{
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this->second_shnum_ = shndx;
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this->second_map_.output_data = output_data;
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return &this->second_map_;
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}
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Input_merge_map* new_map = new Input_merge_map;
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new_map->output_data = output_data;
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this->section_merge_maps_[shndx] = new_map;
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return new_map;
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}
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// Add a mapping.
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void
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Object_merge_map::add_mapping(const Output_section_data* output_data,
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unsigned int shndx,
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section_offset_type input_offset,
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section_size_type length,
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section_offset_type output_offset)
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{
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Input_merge_map* map = this->get_or_make_input_merge_map(output_data, shndx);
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// Try to merge the new entry in the last one we saw.
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if (!map->entries.empty())
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{
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Input_merge_entry& entry(map->entries.back());
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// Use section_size_type to avoid signed/unsigned warnings.
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section_size_type input_offset_u = input_offset;
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section_size_type output_offset_u = output_offset;
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// If this entry is not in order, we need to sort the vector
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// before looking anything up.
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if (input_offset_u < entry.input_offset + entry.length)
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{
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gold_assert(input_offset < entry.input_offset);
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gold_assert(input_offset_u + length
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<= static_cast<section_size_type>(entry.input_offset));
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map->sorted = false;
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}
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else if (entry.input_offset + entry.length == input_offset_u
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&& (output_offset == -1
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? entry.output_offset == -1
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: entry.output_offset + entry.length == output_offset_u))
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{
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entry.length += length;
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return;
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}
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}
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Input_merge_entry entry;
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entry.input_offset = input_offset;
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entry.length = length;
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entry.output_offset = output_offset;
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map->entries.push_back(entry);
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}
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// Get the output offset for an input address.
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bool
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Object_merge_map::get_output_offset(unsigned int shndx,
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section_offset_type input_offset,
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section_offset_type* output_offset)
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{
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Input_merge_map* map = this->get_input_merge_map(shndx);
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if (map == NULL)
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return false;
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if (!map->sorted)
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{
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std::sort(map->entries.begin(), map->entries.end(),
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Input_merge_compare());
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map->sorted = true;
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}
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Input_merge_entry entry;
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entry.input_offset = input_offset;
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std::vector<Input_merge_entry>::const_iterator p =
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std::upper_bound(map->entries.begin(), map->entries.end(),
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entry, Input_merge_compare());
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if (p == map->entries.begin())
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return false;
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--p;
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gold_assert(p->input_offset <= input_offset);
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if (input_offset - p->input_offset
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>= static_cast<section_offset_type>(p->length))
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return false;
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*output_offset = p->output_offset;
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if (*output_offset != -1)
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*output_offset += (input_offset - p->input_offset);
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return true;
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}
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// Return whether this is the merge map for section SHNDX.
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bool
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Object_merge_map::is_merge_section_for(const Output_section_data* output_data,
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unsigned int shndx)
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{
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Input_merge_map* map = this->get_input_merge_map(shndx);
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return map != NULL && map->output_data == output_data;
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}
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// Initialize a mapping from input offsets to output addresses.
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template<int size>
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void
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Object_merge_map::initialize_input_to_output_map(
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unsigned int shndx,
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typename elfcpp::Elf_types<size>::Elf_Addr starting_address,
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Unordered_map<section_offset_type,
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typename elfcpp::Elf_types<size>::Elf_Addr>* initialize_map)
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{
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Input_merge_map* map = this->get_input_merge_map(shndx);
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gold_assert(map != NULL);
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gold_assert(initialize_map->empty());
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// We know how many entries we are going to add.
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// reserve_unordered_map takes an expected count of buckets, not a
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// count of elements, so double it to try to reduce collisions.
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reserve_unordered_map(initialize_map, map->entries.size() * 2);
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for (Input_merge_map::Entries::const_iterator p = map->entries.begin();
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p != map->entries.end();
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++p)
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{
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section_offset_type output_offset = p->output_offset;
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if (output_offset != -1)
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output_offset += starting_address;
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else
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{
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// If we see a relocation against an address we have chosen
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// to discard, we relocate to zero. FIXME: We could also
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// issue a warning in this case; that would require
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// reporting this somehow and checking it in the routines in
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// reloc.h.
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output_offset = 0;
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}
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initialize_map->insert(std::make_pair(p->input_offset, output_offset));
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}
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}
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// Class Output_merge_base.
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// Return the output offset for an input offset. The input address is
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// at offset OFFSET in section SHNDX in OBJECT. If we know the
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// offset, set *POUTPUT and return true. Otherwise return false.
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bool
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Output_merge_base::do_output_offset(const Relobj* object,
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unsigned int shndx,
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section_offset_type offset,
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section_offset_type* poutput) const
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{
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return object->merge_output_offset(shndx, offset, poutput);
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}
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// Record a merged input section for script processing.
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void
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Output_merge_base::record_input_section(Relobj* relobj, unsigned int shndx)
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{
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gold_assert(this->keeps_input_sections_ && relobj != NULL);
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// If this is the first input section, record it. We need do this because
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// this->input_sections_ is unordered.
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if (this->first_relobj_ == NULL)
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{
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this->first_relobj_ = relobj;
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this->first_shndx_ = shndx;
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}
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std::pair<Input_sections::iterator, bool> result =
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this->input_sections_.insert(Section_id(relobj, shndx));
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// We should insert a merge section once only.
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gold_assert(result.second);
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}
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// Class Output_merge_data.
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// Compute the hash code for a fixed-size constant.
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size_t
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Output_merge_data::Merge_data_hash::operator()(Merge_data_key k) const
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{
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const unsigned char* p = this->pomd_->constant(k);
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section_size_type entsize =
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convert_to_section_size_type(this->pomd_->entsize());
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// Fowler/Noll/Vo (FNV) hash (type FNV-1a).
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if (sizeof(size_t) == 8)
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{
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size_t result = static_cast<size_t>(14695981039346656037ULL);
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for (section_size_type i = 0; i < entsize; ++i)
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{
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result &= (size_t) *p++;
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result *= 1099511628211ULL;
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}
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return result;
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}
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else
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{
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size_t result = 2166136261UL;
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for (section_size_type i = 0; i < entsize; ++i)
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{
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result ^= (size_t) *p++;
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result *= 16777619UL;
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}
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return result;
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}
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}
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// Return whether one hash table key equals another.
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bool
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Output_merge_data::Merge_data_eq::operator()(Merge_data_key k1,
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Merge_data_key k2) const
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{
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const unsigned char* p1 = this->pomd_->constant(k1);
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const unsigned char* p2 = this->pomd_->constant(k2);
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return memcmp(p1, p2, this->pomd_->entsize()) == 0;
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}
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// Add a constant to the end of the section contents.
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void
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Output_merge_data::add_constant(const unsigned char* p)
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{
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section_size_type entsize = convert_to_section_size_type(this->entsize());
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section_size_type addralign =
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convert_to_section_size_type(this->addralign());
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section_size_type addsize = std::max(entsize, addralign);
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if (this->len_ + addsize > this->alc_)
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{
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if (this->alc_ == 0)
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this->alc_ = 128 * addsize;
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else
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this->alc_ *= 2;
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this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->alc_));
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if (this->p_ == NULL)
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gold_nomem();
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}
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memcpy(this->p_ + this->len_, p, entsize);
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if (addsize > entsize)
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memset(this->p_ + this->len_ + entsize, 0, addsize - entsize);
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this->len_ += addsize;
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}
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// Add the input section SHNDX in OBJECT to a merged output section
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// which holds fixed length constants. Return whether we were able to
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// handle the section; if not, it will be linked as usual without
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// constant merging.
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bool
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Output_merge_data::do_add_input_section(Relobj* object, unsigned int shndx)
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{
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section_size_type len;
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bool is_new;
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const unsigned char* p = object->decompressed_section_contents(shndx, &len,
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&is_new);
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section_size_type entsize = convert_to_section_size_type(this->entsize());
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if (len % entsize != 0)
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{
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if (is_new)
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delete[] p;
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return false;
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}
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this->input_count_ += len / entsize;
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for (section_size_type i = 0; i < len; i += entsize, p += entsize)
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{
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// Add the constant to the section contents. If we find that it
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// is already in the hash table, we will remove it again.
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Merge_data_key k = this->len_;
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this->add_constant(p);
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std::pair<Merge_data_hashtable::iterator, bool> ins =
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this->hashtable_.insert(k);
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if (!ins.second)
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{
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// Key was already present. Remove the copy we just added.
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this->len_ -= entsize;
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k = *ins.first;
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}
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// Record the offset of this constant in the output section.
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object->add_merge_mapping(this, shndx, i, entsize, k);
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}
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// For script processing, we keep the input sections.
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if (this->keeps_input_sections())
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record_input_section(object, shndx);
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if (is_new)
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delete[] p;
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return true;
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}
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// Set the final data size in a merged output section with fixed size
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// constants.
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void
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Output_merge_data::set_final_data_size()
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{
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// Release the memory we don't need.
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this->p_ = static_cast<unsigned char*>(realloc(this->p_, this->len_));
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// An Output_merge_data object may be empty and realloc is allowed
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// to return a NULL pointer in this case. An Output_merge_data is empty
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// if all its input sections have sizes that are not multiples of entsize.
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gold_assert(this->p_ != NULL || this->len_ == 0);
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this->set_data_size(this->len_);
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}
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// Write the data of a merged output section with fixed size constants
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// to the file.
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void
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Output_merge_data::do_write(Output_file* of)
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{
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of->write(this->offset(), this->p_, this->len_);
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}
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// Write the data to a buffer.
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void
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Output_merge_data::do_write_to_buffer(unsigned char* buffer)
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{
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memcpy(buffer, this->p_, this->len_);
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}
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// Print merge stats to stderr.
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void
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Output_merge_data::do_print_merge_stats(const char* section_name)
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{
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fprintf(stderr,
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_("%s: %s merged constants size: %lu; input: %zu; output: %zu\n"),
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program_name, section_name,
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static_cast<unsigned long>(this->entsize()),
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this->input_count_, this->hashtable_.size());
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}
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// Class Output_merge_string.
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// Add an input section to a merged string section.
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template<typename Char_type>
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bool
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Output_merge_string<Char_type>::do_add_input_section(Relobj* object,
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unsigned int shndx)
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{
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section_size_type sec_len;
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bool is_new;
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const unsigned char* pdata = object->decompressed_section_contents(shndx,
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&sec_len,
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&is_new);
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const Char_type* p = reinterpret_cast<const Char_type*>(pdata);
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const Char_type* pend = p + sec_len / sizeof(Char_type);
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const Char_type* pend0 = pend;
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if (sec_len % sizeof(Char_type) != 0)
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{
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object->error(_("mergeable string section length not multiple of "
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"character size"));
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if (is_new)
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delete[] pdata;
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return false;
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}
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if (pend[-1] != 0)
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{
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gold_warning(_("%s: last entry in mergeable string section '%s' "
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"not null terminated"),
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object->name().c_str(),
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object->section_name(shndx).c_str());
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// Find the end of the last NULL-terminated string in the buffer.
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while (pend0 > p && pend0[-1] != 0)
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--pend0;
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}
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Merged_strings_list* merged_strings_list =
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new Merged_strings_list(object, shndx);
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this->merged_strings_lists_.push_back(merged_strings_list);
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Merged_strings& merged_strings = merged_strings_list->merged_strings;
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// Count the number of non-null strings in the section and size the list.
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size_t count = 0;
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const Char_type* pt = p;
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while (pt < pend0)
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{
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size_t len = string_length(pt);
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if (len != 0)
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++count;
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pt += len + 1;
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}
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if (pend0 < pend)
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++count;
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merged_strings.reserve(count + 1);
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// The index I is in bytes, not characters.
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section_size_type i = 0;
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// We assume here that the beginning of the section is correctly
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// aligned, so each string within the section must retain the same
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// modulo.
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uintptr_t init_align_modulo = (reinterpret_cast<uintptr_t>(pdata)
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& (this->addralign() - 1));
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bool has_misaligned_strings = false;
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while (p < pend)
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{
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size_t len = p < pend0 ? string_length(p) : pend - p;
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// Within merge input section each string must be aligned.
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if (len != 0
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&& ((reinterpret_cast<uintptr_t>(p) & (this->addralign() - 1))
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!= init_align_modulo))
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has_misaligned_strings = true;
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Stringpool::Key key;
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this->stringpool_.add_with_length(p, len, true, &key);
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merged_strings.push_back(Merged_string(i, key));
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p += len + 1;
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i += (len + 1) * sizeof(Char_type);
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}
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// Record the last offset in the input section so that we can
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// compute the length of the last string.
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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)
|
|
(*l)->object->add_merge_mapping(this, (*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.
|