1 // gc.cc -- garbage collection of unused sections
2 
3 // Copyright (C) 2009-2014 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
do_transitive_closure()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().front();
42       this->worklist().pop();
43       if (this->referenced_list().find(entry)
44           == this->referenced_list().end())
45         {
46           this->referenced_list().insert(entry);
47         }
48       else
49         {
50           continue;
51         }
52       Garbage_collection::Section_ref::iterator find_it =
53                 this->section_reloc_map().find(entry);
54       if (find_it == this->section_reloc_map().end())
55           continue;
56       Garbage_collection::Sections_reachable v = find_it->second;
57       // Scan the vector of references for each work_list entry.
58       for (Garbage_collection::Sections_reachable::iterator it_v = v.begin();
59            it_v != v.end();
60            ++it_v)
61         {
62           // Do not add already processed sections to the work_list.
63           if (this->referenced_list().find(*it_v)
64               == this->referenced_list().end())
65             {
66               this->worklist().push(*it_v);
67             }
68         }
69     }
70   this->worklist_ready();
71 }
72 
73 } // End namespace gold.
74 
75