binutils-gdb/gold/merge.h

307 lines
8.7 KiB
C++

// 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,
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.
bool
get_output_offset(const Relobj* object, unsigned int shndx,
section_offset_type offset,
section_offset_type *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,
section_offset_type offset,
section_offset_type* 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, section_offset_type offset,
section_size_type length, section_offset_type 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),
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*);
// Print merge stats to stderr.
void
do_print_merge_stats(const char* section_name);
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_(),
merged_strings_(), input_count_(0)
{
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.
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*);
// 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(); }
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 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.
section_offset_type 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;
// The key in the Stringpool.
Stringpool::Key stringpool_key;
Merged_string(Relobj *objecta, unsigned int shndxa,
section_offset_type offseta, const Char_type* stringa,
size_t lengtha, Stringpool::Key stringpool_keya)
: object(objecta), shndx(shndxa), offset(offseta), string(stringa),
length(lengtha), stringpool_key(stringpool_keya)
{ }
};
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_;
// The number of entries seen in input files.
size_t input_count_;
};
} // End namespace gold.
#endif // !defined(GOLD_MERGE_H)