/*******************************************************************************
 * 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 LREORDER_INCL
#define LREORDER_INCL

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

class TR_BitVector;

namespace TR {
class Block;
class TreeTop;
} // namespace TR

/*
 * Class TR_LocalReordering
 * ========================
 *
 * Local reordering is an optimization that aims to reduce the (register) live
 * ranges of RHS values of stores in two ways:
 *
 * 1) By "delaying" a store closer to its use (if that use is in the same block)
 * so that the RHS value will be live across a smaller range of IL trees once
 * local copy propagation happens and the use is replaced by a commoned
 * reference to the RHS value.
 *
 * 2) By "moving earlier" a store whose RHS is anchored (i.e. evaluated)
 * earlier in the block before the store. In this case, by moving the store
 * earlier, the live range of the RHS value may be reduced (if there was
 * no later use of the RHS value).
 *
 * This optimization's thrust is (register) live range reduction and
 * it runs on IL trees in the common code optimizer. A more general
 * "local live range reduction" (that is the name of the pass) optimization
 * was implemented later and it aims to reduce live ranges in even more
 * cases (including some cases independent of stores). However local reordering
 * was not disabled even after local live range reduction was enabled.
 */

class TR_LocalReordering : public TR::Optimization {
public:
    // Performs local reordering within
    // a basic block.
    //
    TR_LocalReordering(TR::OptimizationManager *manager);

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

    virtual int32_t perform();
    virtual int32_t performOnBlock(TR::Block *);
    virtual void prePerformOnBlocks();
    virtual void postPerformOnBlocks();
    virtual const char *optDetailString() const throw();

private:
    bool transformBlock(TR::Block *);
    void delayDefinitions(TR::Block *);
    void collectUses(TR::Block *);
    void setUseTreeForSymbolReferencesIn(TR::TreeTop *, TR::Node *, vcount_t);
    bool containsBarriers(TR::Block *);
    void insertDefinitionBetween(TR::TreeTop *, TR::TreeTop *);
    bool isAnySymInDefinedOrUsedBy(TR::Node *, vcount_t);
    bool isAnySymInDefinedBy(TR::Node *, vcount_t);
    void moveStoresEarlierIfRhsAnchored(TR::Block *, TR::TreeTop *, TR::Node *, TR::Node *, vcount_t);
    void collectSymbolsUsedAndDefinedInNode(TR::Node *, vcount_t);
    bool insertEarlierIfPossible(TR::TreeTop *, TR::TreeTop *, bool);
    bool isSubtreeCommoned(TR::Node *);

    TR_BitVector *_seenSymbols, *_stopNodes, *_temp;
    TR::TreeTop **_treeTopsAsArray;
    TR::TreeTop **_storeTreesAsArray;
    int32_t _numStoreTreeTops;
    bool _seenUnpinnedInternalPointer;
    int32_t _counter;
};

#endif
