4277535cdc
FIFO is harder to implement and has less locality than LIFO. It is also not necessary to implement a transitive closure, a LIFO works just as well.
69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
// gc.cc -- garbage collection of unused sections
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// Copyright (C) 2009-2015 Free Software Foundation, Inc.
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// Written by Sriraman Tallam <tmsriram@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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#include "gold.h"
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#include "object.h"
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#include "gc.h"
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#include "symtab.h"
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namespace gold
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{
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// Garbage collection uses a worklist style algorithm to determine the
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// transitive closure of all referenced sections.
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void
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Garbage_collection::do_transitive_closure()
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{
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while (!this->worklist().empty())
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{
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// Add elements from the work list to the referenced list
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// one by one.
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Section_id entry = this->worklist().back();
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this->worklist().pop_back();
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if (!this->referenced_list().insert(entry).second)
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continue;
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Garbage_collection::Section_ref::iterator find_it =
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this->section_reloc_map().find(entry);
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if (find_it == this->section_reloc_map().end())
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continue;
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const Garbage_collection::Sections_reachable &v = find_it->second;
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// Scan the vector of references for each work_list entry.
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for (Garbage_collection::Sections_reachable::const_iterator it_v =
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v.begin();
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it_v != v.end();
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++it_v)
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{
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// Do not add already processed sections to the work_list.
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if (this->referenced_list().find(*it_v)
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== this->referenced_list().end())
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{
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this->worklist().push_back(*it_v);
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}
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}
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}
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this->worklist_ready();
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}
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} // End namespace gold.
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