DeadCodeEliminationPass.hpp

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/* src/vm/jit/compiler2/DeadCodeEliminationPass.hpp - DeadCodeEliminationPass

   Copyright (C) 2013
   CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO

   This file is part of CACAO.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   This program is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.

*/

#ifndef _JIT_COMPILER2_DEADCODEELIMINATIONPASS
#define _JIT_COMPILER2_DEADCODEELIMINATIONPASS

#include "vm/jit/compiler2/Pass.hpp"
#include "vm/jit/compiler2/alloc/unordered_map.hpp"
#include "toolbox/Option.hpp"

namespace cacao {
namespace jit {
namespace compiler2 {

// forward declaration 
class Instruction;

/**
 * DeadCodeEliminationPass
 * 
 * This optimization pass removes dead (a.k.a unused) code from the program,
 * based on an algorithm in @cite ReisingerBScThesis. It uses a 'weak'
 * definition of 'dead' which does not take control-flow into account.
 */
class DeadCodeEliminationPass : public Pass {
private:
    typedef alloc::unordered_map<Instruction*,bool>::type InstBoolMapTy;
    typedef alloc::unordered_map<Instruction*,std::size_t>::type InstIntMapTy;
public:
    static Option<bool> enabled;
    DeadCodeEliminationPass() : Pass() {}
    virtual bool run(JITData &JD);
    virtual PassUsage& get_PassUsage(PassUsage &PA) const;

    virtual bool is_enabled() const {
        return DeadCodeEliminationPass::enabled;
    }
};

} // end namespace compiler2
} // end namespace jit
} // end namespace cacao

#endif /* _JIT_COMPILER2_DEADCODEELIMINATIONPASS */


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