/*******************************************************************************
 * Copyright IBM Corp. and others 2000
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#ifndef COMPACTLOCALS_INCL
#define COMPACTLOCALS_INCL

#include <stdint.h>
#include "il/Node.hpp"
#include "infra/IGNode.hpp"
#include "infra/vector.hpp"
#include "optimizer/Optimization.hpp"
#include "optimizer/OptimizationManager.hpp"

class TR_BitVector;
class TR_HashTabInt;
class TR_InterferenceGraph;
class TR_Liveness;

namespace TR {
class AutomaticSymbol;
class Block;
class ResolvedMethodSymbol;
} // namespace TR
template<class T> class TR_Array;

/*
 * Class TR_CompactLocals
 * ======================
 *
 * Compact locals tries to minimize the stack size required by the
 * compiled method. This is done by computing interferences between the
 * live ranges of the locals/temps in the method before code generation
 * is done; based on these interferences, locals that are never live
 * simultaneously can be mapped on to the same stack slot.
 * Liveness information is used by this analysis.
 */

class TR_CompactLocals : public TR::Optimization {
    TR_BitVector *_liveVars;
    TR_BitVector *_prevLiveVars;
    TR_BitVector *_temp;
    TR::vector<TR_IGNode *, TR::Region &> *_localIndexToIGNode;
    TR_InterferenceGraph *_localsIG;
    TR_HashTabInt *_visit;
    TR_Array<TR::AutomaticSymbol *> *_callerLiveSyms;

    void processNodeInPreorder(TR::Node *root, vcount_t visitCount, TR_Liveness *liveLocals, TR::Block *block,
        bool directChildOfTreeTop);
    void createInterferenceBetween(TR_BitVector *bv);
    void createInterferenceBetween(TR_BitVector *bv1, TR_BitVector *bv2);
    void createInterferenceBetweenLocals(int32_t localIndex);
    void doCompactLocals();

public:
    TR_CompactLocals(TR::OptimizationManager *manager);

    static TR::Optimization *create(TR::OptimizationManager *manager)
    {
        return new (manager->allocator()) TR_CompactLocals(manager);
    }

    bool eligibleLocal(TR::AutomaticSymbol *localSym);
    void assignColorsToSymbols(TR_BitVector *bv);

    virtual int32_t perform();
    virtual const char *optDetailString() const throw();
};

#endif
