1// gc.cc -- garbage collection of unused sections 2 3// Copyright (C) 2009-2020 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 29namespace gold 30{ 31 32// Garbage collection uses a worklist style algorithm to determine the 33// transitive closure of all referenced sections. 34void 35Garbage_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