| 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 | |