227 lines
5.5 KiB
C++
227 lines
5.5 KiB
C++
// merge.h -- handle section merging for gold -*- C++ -*-
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#ifndef GOLD_MERGE_H
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#define GOLD_MERGE_H
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#include <climits>
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#include "stringpool.h"
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#include "output.h"
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namespace gold
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{
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// A general class for SHF_MERGE data, to hold functions shared by
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// fixed-size constant data and string data.
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class Output_merge_base : public Output_section_data
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{
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public:
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Output_merge_base(uint64_t entsize)
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: Output_section_data(1), merge_map_(), entsize_(entsize)
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{ }
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// Return the output address for an input address.
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bool
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do_output_address(const Relobj* object, unsigned int shndx, off_t offset,
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uint64_t output_section_address, uint64_t* poutput) const;
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protected:
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// Return the entry size.
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uint64_t
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entsize() const
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{ return this->entsize_; }
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// Add a mapping from an OFFSET in input section SHNDX in object
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// OBJECT to an OUTPUT_OFFSET in the output section.
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void
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add_mapping(Relobj* object, unsigned int shndx, off_t offset,
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off_t output_offset);
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private:
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// We build a mapping from OBJECT/SHNDX/OFFSET to an offset in the
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// output section.
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struct Merge_key
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{
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const Relobj* object;
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unsigned int shndx;
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off_t offset;
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};
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struct Merge_key_less
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{
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bool
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operator()(const Merge_key&, const Merge_key&) const;
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};
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typedef std::map<Merge_key, off_t, Merge_key_less> Merge_map;
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// A mapping from input object/section/offset to offset in output
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// section.
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Merge_map merge_map_;
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// The entry size. For fixed-size constants, this is the size of
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// the constants. For strings, this is the size of a character.
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uint64_t entsize_;
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};
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// Handle SHF_MERGE sections with fixed-size constant data.
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class Output_merge_data : public Output_merge_base
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{
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public:
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Output_merge_data(uint64_t entsize)
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: Output_merge_base(entsize), p_(NULL), len_(0), alc_(0),
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hashtable_(128, Merge_data_hash(this), Merge_data_eq(this))
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{ }
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// Add an input section.
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bool
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do_add_input_section(Relobj* object, unsigned int shndx);
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// Set the final data size.
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void
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do_set_address(uint64_t, off_t);
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// Write the data to the file.
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void
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do_write(Output_file*);
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private:
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// We build a hash table of the fixed-size constants. Each constant
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// is stored as a pointer into the section data we are accumulating.
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// A key in the hash table. This is an offset in the section
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// contents we are building.
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typedef off_t Merge_data_key;
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// Compute the hash code. To do this we need a pointer back to the
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// object holding the data.
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class Merge_data_hash
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{
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public:
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Merge_data_hash(const Output_merge_data* pomd)
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: pomd_(pomd)
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{ }
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size_t
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operator()(Merge_data_key) const;
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private:
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const Output_merge_data* pomd_;
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};
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friend class Merge_data_hash;
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// Compare two entries in the hash table for equality. To do this
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// we need a pointer back to the object holding the data. Note that
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// we now have a pointer to the object stored in two places in the
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// hash table. Fixing this would require specializing the hash
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// table, which would be hard to do portably.
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class Merge_data_eq
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{
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public:
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Merge_data_eq(const Output_merge_data* pomd)
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: pomd_(pomd)
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{ }
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bool
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operator()(Merge_data_key k1, Merge_data_key k2) const;
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private:
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const Output_merge_data* pomd_;
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};
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friend class Merge_data_eq;
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// The type of the hash table.
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typedef Unordered_set<Merge_data_key, Merge_data_hash, Merge_data_eq>
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Merge_data_hashtable;
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// Given a hash table key, which is just an offset into the section
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// data, return a pointer to the corresponding constant.
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const unsigned char*
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constant(Merge_data_key k) const
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{
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gold_assert(k >= 0 && k < this->len_);
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return this->p_ + k;
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}
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// Add a constant to the output.
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void
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add_constant(const unsigned char*);
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// The accumulated data.
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unsigned char* p_;
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// The length of the accumulated data.
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off_t len_;
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// The size of the allocated buffer.
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size_t alc_;
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// The hash table.
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Merge_data_hashtable hashtable_;
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};
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// Handle SHF_MERGE sections with string data. This is a template
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// based on the type of the characters in the string.
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template<typename Char_type>
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class Output_merge_string : public Output_merge_base
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{
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public:
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Output_merge_string()
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: Output_merge_base(sizeof(Char_type)), stringpool_(), hashtable_()
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{ this->stringpool_.set_no_zero_null(); }
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// Add an input section.
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bool
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do_add_input_section(Relobj* object, unsigned int shndx);
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// Set the final data size.
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void
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do_set_address(uint64_t, off_t);
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// Write the data to the file.
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void
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do_write(Output_file*);
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private:
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// As we see input sections, we build a mapping from object, section
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// index and offset to strings.
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struct Merge_string_key
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{
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Relobj* object;
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unsigned int shndx;
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off_t offset;
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Merge_string_key(Relobj *objecta, unsigned int shndxa, off_t offseta)
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: object(objecta), shndx(shndxa), offset(offseta)
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{ }
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};
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struct Merge_string_key_hash
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{
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size_t
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operator()(const Merge_string_key&) const;
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};
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struct Merge_string_key_eq
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{
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bool
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operator()(const Merge_string_key&, const Merge_string_key&) const;
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};
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typedef Unordered_map<Merge_string_key, const Char_type*,
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Merge_string_key_hash, Merge_string_key_eq>
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Merge_string_hashtable;
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// As we see the strings, we add them to a Stringpool.
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Stringpool_template<Char_type> stringpool_;
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// Map from a location in an input object to an entry in the
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// Stringpool.
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Merge_string_hashtable hashtable_;
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};
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} // End namespace gold.
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#endif // !defined(GOLD_MERGE_H)
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