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Diffstat (limited to 'gold/merge.h')
| -rw-r--r-- | gold/merge.h | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/gold/merge.h b/gold/merge.h new file mode 100644 index 0000000..dd97bf2 --- /dev/null +++ b/gold/merge.h @@ -0,0 +1,226 @@ +// merge.h -- handle section merging for gold -*- C++ -*- + +#ifndef GOLD_MERGE_H +#define GOLD_MERGE_H + +#include <climits> + +#include "stringpool.h" +#include "output.h" + +namespace gold +{ + +// 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) + : Output_section_data(1), merge_map_(), entsize_(entsize) + { } + + // Return the output address for an input address. + bool + do_output_address(const Relobj* object, unsigned int shndx, off_t offset, + uint64_t output_section_address, uint64_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 output_offset); + + private: + // We build a mapping from OBJECT/SHNDX/OFFSET to an offset in the + // output section. + struct Merge_key + { + const Relobj* object; + unsigned int shndx; + off_t offset; + }; + + struct Merge_key_less + { + bool + operator()(const Merge_key&, const Merge_key&) const; + }; + + typedef std::map<Merge_key, off_t, Merge_key_less> Merge_map; + + // 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) + : Output_merge_base(entsize), 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 + do_set_address(uint64_t, off_t); + + // 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() + : Output_merge_base(sizeof(Char_type)), stringpool_(false), hashtable_() + { } + + // Add an input section. + bool + do_add_input_section(Relobj* object, unsigned int shndx); + + // Set the final data size. + void + do_set_address(uint64_t, off_t); + + // Write the data to the file. + void + do_write(Output_file*); + + private: + // As we see input sections, we build a mapping from object, section + // index and offset to strings. + struct Merge_string_key + { + Relobj* object; + unsigned int shndx; + off_t offset; + + Merge_string_key(Relobj *objecta, unsigned int shndxa, off_t offseta) + : object(objecta), shndx(shndxa), offset(offseta) + { } + }; + + struct Merge_string_key_hash + { + size_t + operator()(const Merge_string_key&) const; + }; + + struct Merge_string_key_eq + { + bool + operator()(const Merge_string_key&, const Merge_string_key&) const; + }; + + typedef Unordered_map<Merge_string_key, const Char_type*, + Merge_string_key_hash, Merge_string_key_eq> + Merge_string_hashtable; + + // 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. + Merge_string_hashtable hashtable_; +}; + +} // End namespace gold. + +#endif // !defined(GOLD_MERGE_H) |