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Diffstat (limited to 'binutils-2.25/gold/merge.h')
| -rw-r--r-- | binutils-2.25/gold/merge.h | 574 |
1 files changed, 574 insertions, 0 deletions
diff --git a/binutils-2.25/gold/merge.h b/binutils-2.25/gold/merge.h new file mode 100644 index 00000000..92c634a5 --- /dev/null +++ b/binutils-2.25/gold/merge.h @@ -0,0 +1,574 @@ +// merge.h -- handle section merging for gold -*- C++ -*- + +// Copyright 2006, 2007, 2008, 2010 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. + +#ifndef GOLD_MERGE_H +#define GOLD_MERGE_H + +#include <climits> +#include <map> +#include <vector> + +#include "stringpool.h" +#include "output.h" + +namespace gold +{ + +class Merge_map; + +// For each object with merge sections, we store an Object_merge_map. +// This is used to map locations in input sections to a merged output +// section. The output section itself is not recorded here--it can be +// found in the output_sections_ field of the Object. + +class Object_merge_map +{ + public: + Object_merge_map() + : first_shnum_(-1U), first_map_(), + second_shnum_(-1U), second_map_(), + section_merge_maps_() + { } + + ~Object_merge_map(); + + // Add a mapping for MERGE_MAP, for the bytes from OFFSET to OFFSET + // + LENGTH in the input section SHNDX to OUTPUT_OFFSET in the + // output section. An OUTPUT_OFFSET of -1 means that the bytes are + // discarded. OUTPUT_OFFSET is relative to the start of the merged + // data in the output section. + void + add_mapping(const Merge_map*, unsigned int shndx, section_offset_type offset, + section_size_type length, section_offset_type output_offset); + + // Get the output offset for an input address. MERGE_MAP is the map + // we are looking for, or NULL if we don't care. The input address + // is at offset OFFSET in section SHNDX. This sets *OUTPUT_OFFSET + // to the offset in the output section; this will be -1 if the bytes + // are not being copied to the output. This returns true if the + // mapping is known, false otherwise. *OUTPUT_OFFSET is relative to + // the start of the merged data in the output section. + bool + get_output_offset(const Merge_map*, unsigned int shndx, + section_offset_type offset, + section_offset_type* output_offset); + + // Return whether this is the merge map for section SHNDX. + bool + is_merge_section_for(const Merge_map*, unsigned int shndx); + + // Initialize an mapping from input offsets to output addresses for + // section SHNDX. STARTING_ADDRESS is the output address of the + // merged section. + template<int size> + void + 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>*); + + private: + // Map input section offsets to a length and an output section + // offset. An output section offset of -1 means that this part of + // the input section is being discarded. + struct Input_merge_entry + { + // The offset in the input section. + section_offset_type input_offset; + // The length. + section_size_type length; + // The offset in the output section. + section_offset_type output_offset; + }; + + // A less-than comparison routine for Input_merge_entry. + struct Input_merge_compare + { + bool + operator()(const Input_merge_entry& i1, const Input_merge_entry& i2) const + { return i1.input_offset < i2.input_offset; } + }; + + // A list of entries for a particular input section. + struct Input_merge_map + { + typedef std::vector<Input_merge_entry> Entries; + + // We store these with the Relobj, and we look them up by input + // section. It is possible to have two different merge maps + // associated with a single output section. For example, this + // happens routinely with .rodata, when merged string constants + // and merged fixed size constants are both put into .rodata. The + // output offset that we store is not the offset from the start of + // the output section; it is the offset from the start of the + // merged data in the output section. That means that the caller + // is going to add the offset of the merged data within the output + // section, which means that the caller needs to know which set of + // merged data it found the entry in. So it's not enough to find + // this data based on the input section and the output section; we + // also have to find it based on a set of merged data in the + // output section. In order to verify that we are looking at the + // right data, we store a pointer to the Merge_map here, and we + // pass in a pointer when looking at the data. If we are asked to + // look up information for a different Merge_map, we report that + // we don't have it, rather than trying a lookup and returning an + // answer which will receive the wrong offset. + const Merge_map* merge_map; + // The list of mappings. + Entries entries; + // Whether the ENTRIES field is sorted by input_offset. + bool sorted; + + Input_merge_map() + : merge_map(NULL), entries(), sorted(true) + { } + }; + + // Map input section indices to merge maps. + typedef std::map<unsigned int, Input_merge_map*> Section_merge_maps; + + // Return a pointer to the Input_merge_map to use for the input + // section SHNDX, or NULL. + Input_merge_map* + get_input_merge_map(unsigned int shndx); + + // Get or make the Input_merge_map to use for the section SHNDX + // with MERGE_MAP. + Input_merge_map* + get_or_make_input_merge_map(const Merge_map* merge_map, unsigned int shndx); + + // Any given object file will normally only have a couple of input + // sections with mergeable contents. So we keep the first two input + // section numbers inline, and push any further ones into a map. A + // value of -1U in first_shnum_ or second_shnum_ means that we don't + // have a corresponding entry. + unsigned int first_shnum_; + Input_merge_map first_map_; + unsigned int second_shnum_; + Input_merge_map second_map_; + Section_merge_maps section_merge_maps_; +}; + +// This class manages mappings from input sections to offsets in an +// output section. This is used where input sections are merged. The +// actual data is stored in fields in Object. + +class Merge_map +{ + public: + Merge_map() + { } + + // Add a mapping for the bytes from OFFSET to OFFSET + LENGTH in the + // input section SHNDX in object OBJECT to OUTPUT_OFFSET in the + // output section. An OUTPUT_OFFSET of -1 means that the bytes are + // discarded. OUTPUT_OFFSET is not the offset from the start of the + // output section, it is the offset from the start of the merged + // data within the output section. + void + add_mapping(Relobj* object, unsigned int shndx, + section_offset_type offset, section_size_type length, + section_offset_type 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 output section; this will be + // -1 if the bytes are not being copied to the output. This returns + // true if the mapping is known, false otherwise. This returns the + // value stored by add_mapping, namely the offset from the start of + // the merged data within the output section. + bool + get_output_offset(const Relobj* object, unsigned int shndx, + section_offset_type offset, + section_offset_type* output_offset) const; + + // Return whether this is the merge mapping for section SHNDX in + // OBJECT. This should return true when get_output_offset would + // return true for some input offset. + bool + is_merge_section_for(const Relobj* object, unsigned int shndx) const; +}; + +// A general class for SHF_MERGE data, to hold functions shared by +// fixed-size constant data and string data. + +class Output_merge_base : public Output_section_data +{ + public: + Output_merge_base(uint64_t entsize, uint64_t addralign) + : Output_section_data(addralign), merge_map_(), entsize_(entsize), + keeps_input_sections_(false), first_relobj_(NULL), first_shndx_(-1), + input_sections_() + { } + + // Return the entry size. + uint64_t + entsize() const + { return this->entsize_; } + + // Whether this is a merge string section. This is only true of + // Output_merge_string. + bool + is_string() + { return this->do_is_string(); } + + // Whether this keeps input sections. + bool + keeps_input_sections() const + { return this->keeps_input_sections_; } + + // Set the keeps-input-sections flag. This is virtual so that sub-classes + // can perform additional checks. + void + set_keeps_input_sections() + { this->do_set_keeps_input_sections(); } + + // Return the object of the first merged input section. This used + // for script processing. This is NULL if merge section is empty. + Relobj* + first_relobj() const + { return this->first_relobj_; } + + // Return the section index of the first merged input section. This + // is used for script processing. This is valid only if merge section + // is not valid. + unsigned int + first_shndx() const + { + gold_assert(this->first_relobj_ != NULL); + return this->first_shndx_; + } + + // Set of merged input sections. + typedef Unordered_set<Section_id, Section_id_hash> Input_sections; + + // Beginning of merged input sections. + Input_sections::const_iterator + input_sections_begin() const + { + gold_assert(this->keeps_input_sections_); + return this->input_sections_.begin(); + } + + // Beginning of merged input sections. + Input_sections::const_iterator + input_sections_end() const + { + gold_assert(this->keeps_input_sections_); + return this->input_sections_.end(); + } + + protected: + // Return the output offset for an input offset. + bool + do_output_offset(const Relobj* object, unsigned int shndx, + section_offset_type offset, + section_offset_type* poutput) const; + + // Return whether this is the merge section for an input section. + bool + do_is_merge_section_for(const Relobj*, unsigned int shndx) const; + + // Add a mapping from an OFFSET in input section SHNDX in object + // OBJECT to an OUTPUT_OFFSET in the output section. OUTPUT_OFFSET + // is the offset from the start of the merged data in the output + // section. + void + add_mapping(Relobj* object, unsigned int shndx, section_offset_type offset, + section_size_type length, section_offset_type output_offset) + { + this->merge_map_.add_mapping(object, shndx, offset, length, output_offset); + } + + // This may be overridden by the child class. + virtual bool + do_is_string() + { return false; } + + // This may be overridden by the child class. + virtual void + do_set_keeps_input_sections() + { this->keeps_input_sections_ = true; } + + // Record the merged input section for script processing. + void + record_input_section(Relobj* relobj, unsigned int shndx); + + private: + // A mapping from input object/section/offset to offset in output + // section. + Merge_map merge_map_; + // The entry size. For fixed-size constants, this is the size of + // the constants. For strings, this is the size of a character. + uint64_t entsize_; + // Whether we keep input sections. + bool keeps_input_sections_; + // Object of the first merged input section. We use this for script + // processing. + Relobj* first_relobj_; + // Section index of the first merged input section. + unsigned int first_shndx_; + // Input sections. We only keep them is keeps_input_sections_ is true. + Input_sections input_sections_; +}; + +// Handle SHF_MERGE sections with fixed-size constant data. + +class Output_merge_data : public Output_merge_base +{ + public: + Output_merge_data(uint64_t entsize, uint64_t addralign) + : Output_merge_base(entsize, addralign), p_(NULL), len_(0), alc_(0), + input_count_(0), + hashtable_(128, Merge_data_hash(this), Merge_data_eq(this)) + { } + + protected: + // Add an input section. + bool + do_add_input_section(Relobj* object, unsigned int shndx); + + // Set the final data size. + void + set_final_data_size(); + + // Write the data to the file. + void + do_write(Output_file*); + + // Write the data to a buffer. + void + do_write_to_buffer(unsigned char*); + + // Write to a map file. + void + do_print_to_mapfile(Mapfile* mapfile) const + { mapfile->print_output_data(this, _("** merge constants")); } + + // Print merge stats to stderr. + void + do_print_merge_stats(const char* section_name); + + // Set keeps-input-sections flag. + void + do_set_keeps_input_sections() + { + gold_assert(this->input_count_ == 0); + Output_merge_base::do_set_keeps_input_sections(); + } + + private: + // We build a hash table of the fixed-size constants. Each constant + // is stored as a pointer into the section data we are accumulating. + + // A key in the hash table. This is an offset in the section + // contents we are building. + typedef section_offset_type Merge_data_key; + + // Compute the hash code. To do this we need a pointer back to the + // object holding the data. + class Merge_data_hash + { + public: + Merge_data_hash(const Output_merge_data* pomd) + : pomd_(pomd) + { } + + size_t + operator()(Merge_data_key) const; + + private: + const Output_merge_data* pomd_; + }; + + friend class Merge_data_hash; + + // Compare two entries in the hash table for equality. To do this + // we need a pointer back to the object holding the data. Note that + // we now have a pointer to the object stored in two places in the + // hash table. Fixing this would require specializing the hash + // table, which would be hard to do portably. + class Merge_data_eq + { + public: + Merge_data_eq(const Output_merge_data* pomd) + : pomd_(pomd) + { } + + bool + operator()(Merge_data_key k1, Merge_data_key k2) const; + + private: + const Output_merge_data* pomd_; + }; + + friend class Merge_data_eq; + + // The type of the hash table. + typedef Unordered_set<Merge_data_key, Merge_data_hash, Merge_data_eq> + Merge_data_hashtable; + + // Given a hash table key, which is just an offset into the section + // data, return a pointer to the corresponding constant. + const unsigned char* + constant(Merge_data_key k) const + { + gold_assert(k >= 0 && k < static_cast<section_offset_type>(this->len_)); + return this->p_ + k; + } + + // Add a constant to the output. + void + add_constant(const unsigned char*); + + // The accumulated data. + unsigned char* p_; + // The length of the accumulated data. + section_size_type len_; + // The size of the allocated buffer. + section_size_type alc_; + // The number of entries seen in input files. + size_t input_count_; + // The hash table. + Merge_data_hashtable hashtable_; +}; + +// Handle SHF_MERGE sections with string data. This is a template +// based on the type of the characters in the string. + +template<typename Char_type> +class Output_merge_string : public Output_merge_base +{ + public: + Output_merge_string(uint64_t addralign) + : Output_merge_base(sizeof(Char_type), addralign), stringpool_(addralign), + merged_strings_lists_(), input_count_(0), input_size_(0) + { + this->stringpool_.set_no_zero_null(); + } + + protected: + // Add an input section. + bool + do_add_input_section(Relobj* object, unsigned int shndx); + + // Do all the final processing after the input sections are read in. + // Returns the final data size. + section_size_type + finalize_merged_data(); + + // Set the final data size. + void + set_final_data_size(); + + // Write the data to the file. + void + do_write(Output_file*); + + // Write the data to a buffer. + void + do_write_to_buffer(unsigned char*); + + // Write to a map file. + void + do_print_to_mapfile(Mapfile* mapfile) const + { mapfile->print_output_data(this, _("** merge strings")); } + + // Print merge stats to stderr. + void + do_print_merge_stats(const char* section_name); + + // Writes the stringpool to a buffer. + void + stringpool_to_buffer(unsigned char* buffer, section_size_type buffer_size) + { this->stringpool_.write_to_buffer(buffer, buffer_size); } + + // Clears all the data in the stringpool, to save on memory. + void + clear_stringpool() + { this->stringpool_.clear(); } + + // Whether this is a merge string section. + virtual bool + do_is_string() + { return true; } + + // Set keeps-input-sections flag. + void + do_set_keeps_input_sections() + { + gold_assert(this->input_count_ == 0); + Output_merge_base::do_set_keeps_input_sections(); + } + + private: + // The name of the string type, for stats. + const char* + string_name(); + + // As we see input sections, we build a mapping from object, section + // index and offset to strings. + struct Merged_string + { + // The offset in the input section. + section_offset_type offset; + // The key in the Stringpool. + Stringpool::Key stringpool_key; + + Merged_string(section_offset_type offseta, Stringpool::Key stringpool_keya) + : offset(offseta), stringpool_key(stringpool_keya) + { } + }; + + typedef std::vector<Merged_string> Merged_strings; + + struct Merged_strings_list + { + // The input object where the strings were found. + Relobj* object; + // The input section in the input object. + unsigned int shndx; + // The list of merged strings. + Merged_strings merged_strings; + + Merged_strings_list(Relobj* objecta, unsigned int shndxa) + : object(objecta), shndx(shndxa), merged_strings() + { } + }; + + typedef std::vector<Merged_strings_list*> Merged_strings_lists; + + // As we see the strings, we add them to a Stringpool. + Stringpool_template<Char_type> stringpool_; + // Map from a location in an input object to an entry in the + // Stringpool. + Merged_strings_lists merged_strings_lists_; + // The number of entries seen in input files. + size_t input_count_; + // The total size of input sections. + size_t input_size_; +}; + +} // End namespace gold. + +#endif // !defined(GOLD_MERGE_H) |