--- /dev/null
+// 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"
+#include "icf.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_enabled()
+ && 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
projects / msp430-binutils.git / blobdiff