| // merge.h -- handle section merging for gold -*- C++ -*- |
| |
| // Copyright 2006, 2007 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 "stringpool.h" |
| #include "output.h" |
| |
| namespace gold |
| { |
| |
| // 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. |
| void |
| add_mapping(Relobj* object, unsigned int shndx, off_t offset, off_t length, |
| off_t 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. |
| bool |
| get_output_offset(const Relobj* object, unsigned int shndx, off_t offset, |
| off_t *output_offset) 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) |
| { } |
| |
| // Return the output offset for an input offset. |
| bool |
| do_output_offset(const Relobj* object, unsigned int shndx, off_t offset, |
| off_t* poutput) const; |
| |
| protected: |
| // Return the entry size. |
| uint64_t |
| entsize() const |
| { return this->entsize_; } |
| |
| // Add a mapping from an OFFSET in input section SHNDX in object |
| // OBJECT to an OUTPUT_OFFSET in the output section. |
| void |
| add_mapping(Relobj* object, unsigned int shndx, off_t offset, |
| off_t length, off_t output_offset) |
| { |
| this->merge_map_.add_mapping(object, shndx, offset, length, output_offset); |
| } |
| |
| 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_; |
| }; |
| |
| // 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), |
| hashtable_(128, Merge_data_hash(this), Merge_data_eq(this)) |
| { } |
| |
| // 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*); |
| |
| 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 off_t 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 < 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. |
| off_t len_; |
| // The size of the allocated buffer. |
| size_t alc_; |
| // 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_(), |
| merged_strings_() |
| { |
| gold_assert(addralign <= sizeof(Char_type)); |
| 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. |
| off_t |
| finalize_merged_data(); |
| |
| // Set the final data size. |
| void |
| set_final_data_size(); |
| |
| // Write the data to the file. |
| void |
| do_write(Output_file*); |
| |
| // Writes the stringpool to a buffer. |
| void |
| stringpool_to_buffer(char* buffer, size_t buffer_size) |
| { this->stringpool_.write_to_buffer(buffer, buffer_size); } |
| |
| // Clears all the data in the stringpool, to save on memory. |
| void |
| clear_stringpool() |
| { stringpool_.clear(); } |
| |
| private: |
| // As we see input sections, we build a mapping from object, section |
| // index and offset to strings. |
| struct Merged_string |
| { |
| // The input object where the string was found. |
| Relobj* object; |
| // The input section in the input object. |
| unsigned int shndx; |
| // The offset in the input section. |
| off_t offset; |
| // The string itself, a pointer into a Stringpool. |
| const Char_type* string; |
| // The length of the string in bytes, including the null terminator. |
| size_t length; |
| |
| Merged_string(Relobj *objecta, unsigned int shndxa, off_t offseta, |
| const Char_type* stringa, size_t lengtha) |
| : object(objecta), shndx(shndxa), offset(offseta), string(stringa), |
| length(lengtha) |
| { } |
| }; |
| |
| typedef std::vector<Merged_string> Merged_strings; |
| |
| // 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 merged_strings_; |
| }; |
| |
| } // End namespace gold. |
| |
| #endif // !defined(GOLD_MERGE_H) |