256 lines
7.7 KiB
C++
256 lines
7.7 KiB
C++
// gc.h -- garbage collection of unused sections
|
|
|
|
// Copyright 2009 Free Software Foundation, Inc.
|
|
// Written by Sriraman Tallam <tmsriram@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_GC_H
|
|
#define GOLD_GC_H
|
|
|
|
#include <queue>
|
|
#include <vector>
|
|
|
|
#include "elfcpp.h"
|
|
#include "symtab.h"
|
|
|
|
namespace gold
|
|
{
|
|
|
|
class Object;
|
|
|
|
template<int size, bool big_endian>
|
|
class Sized_relobj;
|
|
|
|
template<int sh_type, int size, bool big_endian>
|
|
class Reloc_types;
|
|
|
|
class Output_section;
|
|
class General_options;
|
|
class Layout;
|
|
|
|
typedef std::pair<Object *, unsigned int> Section_id;
|
|
|
|
class Garbage_collection
|
|
{
|
|
struct Section_id_hash
|
|
{
|
|
size_t operator()(const Section_id& loc) const
|
|
{ return reinterpret_cast<uintptr_t>(loc.first) ^ loc.second; }
|
|
};
|
|
|
|
public:
|
|
|
|
typedef Unordered_set<Section_id, Section_id_hash> Sections_reachable;
|
|
typedef std::map<Section_id, Sections_reachable> Section_ref;
|
|
typedef std::queue<Section_id> Worklist_type;
|
|
|
|
Garbage_collection()
|
|
: is_worklist_ready_(false)
|
|
{ }
|
|
|
|
// Accessor methods for the private members.
|
|
|
|
Sections_reachable&
|
|
referenced_list()
|
|
{ return referenced_list_; }
|
|
|
|
Section_ref&
|
|
section_reloc_map()
|
|
{ return this->section_reloc_map_; }
|
|
|
|
Worklist_type&
|
|
worklist()
|
|
{ return this->work_list_; }
|
|
|
|
bool
|
|
is_worklist_ready()
|
|
{ return this->is_worklist_ready_; }
|
|
|
|
void
|
|
worklist_ready()
|
|
{ this->is_worklist_ready_ = true; }
|
|
|
|
void
|
|
do_transitive_closure();
|
|
|
|
bool
|
|
is_section_garbage(Object* obj, unsigned int shndx)
|
|
{ return (this->referenced_list().find(Section_id(obj, shndx))
|
|
== this->referenced_list().end()); }
|
|
private:
|
|
|
|
Worklist_type work_list_;
|
|
bool is_worklist_ready_;
|
|
Section_ref section_reloc_map_;
|
|
Sections_reachable referenced_list_;
|
|
};
|
|
|
|
// Data to pass between successive invocations of do_layout
|
|
// in object.cc while garbage collecting. This data structure
|
|
// is filled by using the data from Read_symbols_data.
|
|
|
|
struct Symbols_data
|
|
{
|
|
// Section headers.
|
|
unsigned char* section_headers_data;
|
|
// Section names.
|
|
unsigned char* section_names_data;
|
|
// Size of section name data in bytes.
|
|
section_size_type section_names_size;
|
|
// Symbol data.
|
|
unsigned char* symbols_data;
|
|
// Size of symbol data in bytes.
|
|
section_size_type symbols_size;
|
|
// Offset of external symbols within symbol data. This structure
|
|
// sometimes contains only external symbols, in which case this will
|
|
// be zero. Sometimes it contains all symbols.
|
|
section_offset_type external_symbols_offset;
|
|
// Symbol names.
|
|
unsigned char* symbol_names_data;
|
|
// Size of symbol name data in bytes.
|
|
section_size_type symbol_names_size;
|
|
};
|
|
|
|
// This function implements the generic part of reloc
|
|
// processing to map a section to all the sections it
|
|
// references through relocs. It is called only during
|
|
// garbage collection (--gc-sections) and identical code
|
|
// folding (--icf).
|
|
|
|
template<int size, bool big_endian, typename Target_type, int sh_type,
|
|
typename Scan>
|
|
inline void
|
|
gc_process_relocs(
|
|
const General_options& ,
|
|
Symbol_table* symtab,
|
|
Layout*,
|
|
Target_type* ,
|
|
Sized_relobj<size, big_endian>* src_obj,
|
|
unsigned int src_indx,
|
|
const unsigned char* prelocs,
|
|
size_t reloc_count,
|
|
Output_section*,
|
|
bool ,
|
|
size_t local_count,
|
|
const unsigned char* plocal_syms)
|
|
{
|
|
Object *dst_obj;
|
|
unsigned int dst_indx;
|
|
|
|
typedef typename Reloc_types<sh_type, size, big_endian>::Reloc Reltype;
|
|
const int reloc_size = Reloc_types<sh_type, size, big_endian>::reloc_size;
|
|
const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
|
|
|
|
std::vector<Section_id>* secvec = NULL;
|
|
std::vector<Symbol*>* symvec = NULL;
|
|
std::vector<std::pair<long long, long long> >* addendvec = NULL;
|
|
bool is_icf_tracked = false;
|
|
|
|
if (parameters->options().icf()
|
|
&& is_prefix_of(".text.", (src_obj)->section_name(src_indx).c_str()))
|
|
{
|
|
is_icf_tracked = true;
|
|
Section_id src_id(src_obj, src_indx);
|
|
secvec = &symtab->icf()->section_reloc_list()[src_id];
|
|
symvec = &symtab->icf()->symbol_reloc_list()[src_id];
|
|
addendvec = &symtab->icf()->addend_reloc_list()[src_id];
|
|
}
|
|
|
|
for (size_t i = 0; i < reloc_count; ++i, prelocs += reloc_size)
|
|
{
|
|
Reltype reloc(prelocs);
|
|
typename elfcpp::Elf_types<size>::Elf_WXword r_info = reloc.get_r_info();
|
|
unsigned int r_sym = elfcpp::elf_r_sym<size>(r_info);
|
|
typename elfcpp::Elf_types<size>::Elf_Swxword addend =
|
|
Reloc_types<sh_type, size, big_endian>::get_reloc_addend_noerror(&reloc);
|
|
|
|
if (r_sym < local_count)
|
|
{
|
|
gold_assert(plocal_syms != NULL);
|
|
typename elfcpp::Sym<size, big_endian> lsym(plocal_syms
|
|
+ r_sym * sym_size);
|
|
unsigned int shndx = lsym.get_st_shndx();
|
|
bool is_ordinary;
|
|
shndx = src_obj->adjust_sym_shndx(r_sym, shndx, &is_ordinary);
|
|
if (!is_ordinary)
|
|
continue;
|
|
dst_obj = src_obj;
|
|
dst_indx = shndx;
|
|
Section_id dst_id(dst_obj, dst_indx);
|
|
if (is_icf_tracked)
|
|
{
|
|
(*secvec).push_back(dst_id);
|
|
(*symvec).push_back(NULL);
|
|
long long symvalue = static_cast<long long>(lsym.get_st_value());
|
|
(*addendvec).push_back(std::make_pair(symvalue,
|
|
static_cast<long long>(addend)));
|
|
}
|
|
if (shndx == src_indx)
|
|
continue;
|
|
}
|
|
else
|
|
{
|
|
Symbol* gsym = src_obj->global_symbol(r_sym);
|
|
gold_assert(gsym != NULL);
|
|
if (gsym->is_forwarder())
|
|
gsym = symtab->resolve_forwards(gsym);
|
|
if (gsym->source() != Symbol::FROM_OBJECT)
|
|
continue;
|
|
bool is_ordinary;
|
|
dst_obj = gsym->object();
|
|
dst_indx = gsym->shndx(&is_ordinary);
|
|
if (!is_ordinary)
|
|
continue;
|
|
Section_id dst_id(dst_obj, dst_indx);
|
|
if (is_icf_tracked)
|
|
{
|
|
(*secvec).push_back(dst_id);
|
|
(*symvec).push_back(gsym);
|
|
Sized_symbol<size>* sized_gsym =
|
|
static_cast<Sized_symbol<size>* >(gsym);
|
|
long long symvalue =
|
|
static_cast<long long>(sized_gsym->value());
|
|
(*addendvec).push_back(std::make_pair(symvalue,
|
|
static_cast<long long>(addend)));
|
|
}
|
|
}
|
|
if (parameters->options().gc_sections())
|
|
{
|
|
Section_id src_id(src_obj, src_indx);
|
|
Section_id dst_id(dst_obj, dst_indx);
|
|
Garbage_collection::Section_ref::iterator map_it;
|
|
map_it = symtab->gc()->section_reloc_map().find(src_id);
|
|
if (map_it == symtab->gc()->section_reloc_map().end())
|
|
{
|
|
symtab->gc()->section_reloc_map()[src_id].insert(dst_id);
|
|
}
|
|
else
|
|
{
|
|
Garbage_collection::Sections_reachable& v(map_it->second);
|
|
v.insert(dst_id);
|
|
}
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
|
|
} // End of namespace gold.
|
|
|
|
#endif
|