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// layout.h -- lay out output file sections for gold -*- C++ -*-
#ifndef GOLD_LAYOUT_H
#define GOLD_LAYOUT_H
#include <list>
#include <string>
#include <utility>
#include <vector>
#include "options.h"
#include "workqueue.h"
#include "object.h"
#include "stringpool.h"
namespace gold
{
class Output_section;
class Output_segment;
// This Task handles mapping the input sections to output sections and
// laying them out in memory.
class Layout_task : public Task
{
public:
// OPTIONS is the command line options, INPUT_OBJECTS is the list of
// input objects, THIS_BLOCKER is a token which blocks this task
// from executing until all the input symbols have been read.
Layout_task(const General_options& options, const Object_list* input_objects,
Task_token* this_blocker)
: options_(options), input_objects_(input_objects),
this_blocker_(this_blocker)
{ }
~Layout_task();
// The standard Task methods.
Is_runnable_type
is_runnable(Workqueue*);
Task_locker*
locks(Workqueue*);
void
run(Workqueue*);
private:
Layout_task(const Layout_task&);
Layout_task& operator=(const Layout_task&);
const General_options& options_;
const Object_list* input_objects_;
Task_token* this_blocker_;
};
// This class handles the details of laying out input sections.
class Layout
{
public:
Layout(const General_options& options)
: options_(options), namepool_(), signatures_(),
section_name_map_(), segment_list_()
{ }
// Given an input section named NAME with data in SHDR from the
// object file OBJECT, return the output section where this input
// section should go. Set *OFFSET to the offset within the output
// section.
template<int size, bool big_endian>
Output_section*
layout(Object *object, const char* name,
const elfcpp::Shdr<size, big_endian>& shdr, off_t* offset);
// Return whether a section is a .gnu.linkonce section, given the
// section name.
static inline bool
is_linkonce(const char* name)
{ return strncmp(name, ".gnu.linkonce", sizeof(".gnu.linkonce") - 1) == 0; }
// Record the signature of a comdat section, and return whether to
// include it in the link. The GROUP parameter is true for a
// section group signature, false for a signature derived from a
// .gnu.linkonce section.
bool
add_comdat(const char*, bool group);
private:
Layout(const Layout&);
Layout& operator=(const Layout&);
// Mapping from .gnu.linkonce section names to output section names.
struct Linkonce_mapping
{
const char* from;
int fromlen;
const char* to;
};
static const Linkonce_mapping linkonce_mapping[];
static const int linkonce_mapping_count;
// Return whether to include this section in the link.
template<int size, bool big_endian>
bool
include_section(Object* object, const char* name,
const elfcpp::Shdr<size, big_endian>&);
// Return the output section name to use for a linkonce section
// name.
static const char*
linkonce_output_name(const char* name);
// Create a new Output_section.
Output_section*
make_output_section(const char* name, elfcpp::Elf_Word type,
elfcpp::Elf_Xword flags);
// Return whether SEG1 comes before SEG2 in the output file.
static bool
Layout::segment_precedes(const Output_segment* seg1,
const Output_segment* seg2);
// Map from section flags to segment flags.
static elfcpp::Elf_Word
section_flags_to_segment(elfcpp::Elf_Xword flags);
// A mapping used for group signatures.
typedef Unordered_map<std::string, bool> Signatures;
// Mapping from input section name/type/flags to output section. We
// use canonicalized strings here.
typedef std::pair<const char*,
std::pair<elfcpp::Elf_Word, elfcpp::Elf_Xword> > Key;
struct Hash_key
{
size_t
operator()(const Key& k) const;
};
typedef Unordered_map<Key, Output_section*, Hash_key> Section_name_map;
// A comparison class for segments.
struct Compare_segments
{
bool
operator()(const Output_segment* seg1, const Output_segment* seg2)
{ return Layout::segment_precedes(seg1, seg2); }
};
// The list of segments.
typedef std::list<Output_segment*> Segment_list;
// The list of sections not attached to a segment.
typedef std::list<Output_section*> Section_list;
// A reference to the options on the command line.
const General_options& options_;
// The output section names.
Stringpool namepool_;
// The list of group sections and linkonce sections which we have seen.
Signatures signatures_;
// The mapping from input section name/type/flags to output sections.
Section_name_map section_name_map_;
// The list of output segments.
Segment_list segment_list_;
// The list of output sections which are not attached to any output
// segment.
Section_list section_list_;
};
} // End namespace gold.
#endif // !defined(GOLD_LAYOUT_H)
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