1 // gc.cc -- garbage collection of unused sections 2 3 // Copyright (C) 2009-2016 Free Software Foundation, Inc. 4 // Written by Sriraman Tallam <tmsriram@google.com>. 5 6 // This file is part of gold. 7 8 // This program is free software; you can redistribute it and/or modify 9 // it under the terms of the GNU General Public License as published by 10 // the Free Software Foundation; either version 3 of the License, or 11 // (at your option) any later version. 12 13 // This program is distributed in the hope that it will be useful, 14 // but WITHOUT ANY WARRANTY; without even the implied warranty of 15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 // GNU General Public License for more details. 17 18 // You should have received a copy of the GNU General Public License 19 // along with this program; if not, write to the Free Software 20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, 21 // MA 02110-1301, USA. 22 23 24 #include "gold.h" 25 #include "object.h" 26 #include "gc.h" 27 #include "symtab.h" 28 29 namespace gold 30 { 31 32 // Garbage collection uses a worklist style algorithm to determine the 33 // transitive closure of all referenced sections. 34 void 35 Garbage_collection::do_transitive_closure() 36 { 37 while (!this->worklist().empty()) 38 { 39 // Add elements from the work list to the referenced list 40 // one by one. 41 Section_id entry = this->worklist().back(); 42 this->worklist().pop_back(); 43 if (!this->referenced_list().insert(entry).second) 44 continue; 45 Garbage_collection::Section_ref::iterator find_it = 46 this->section_reloc_map().find(entry); 47 if (find_it == this->section_reloc_map().end()) 48 continue; 49 const Garbage_collection::Sections_reachable &v = find_it->second; 50 // Scan the vector of references for each work_list entry. 51 for (Garbage_collection::Sections_reachable::const_iterator it_v = 52 v.begin(); 53 it_v != v.end(); 54 ++it_v) 55 { 56 // Do not add already processed sections to the work_list. 57 if (this->referenced_list().find(*it_v) 58 == this->referenced_list().end()) 59 { 60 this->worklist().push_back(*it_v); 61 } 62 } 63 } 64 this->worklist_ready(); 65 } 66 67 } // End namespace gold. 68 69