/*
 * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.sun.c1x.ir;

import java.util.*;

import com.sun.c1x.util.*;
import com.sun.c1x.value.*;
import com.sun.cri.ci.*;

/**
 * The {@code BlockEnd} instruction is a base class for all instructions that end a basic
 * block, including branches, switches, throws, and goto's.
 *
 * @author Ben L. Titzer
 */
public abstract class BlockEnd extends Instruction {

    BlockBegin begin;
    final List<BlockBegin> successors;
    FrameState stateAfter;

    /**
     * Constructs a new block end with the specified value type.
     * @param kind the type of the value produced by this instruction
     * @param stateAfter the frame state at the end of this block
     * @param isSafepoint {@code true} if this instruction is a safepoint instruction
     * @param successors the list of successor blocks. If {@code null}, a new one will be created.
     */
    public BlockEnd(CiKind kind, FrameState stateAfter, boolean isSafepoint, List<BlockBegin> successors) {
        super(kind);
        this.successors = successors == null ? new ArrayList<BlockBegin>(2) : successors;
        setStateAfter(stateAfter);
        if (isSafepoint) {
            setFlag(Value.Flag.IsSafepoint);
        }
    }

    public BlockEnd(CiKind kind, FrameState stateAfter, boolean isSafepoint) {
        this(kind, stateAfter, isSafepoint, null);
    }

    /**
     * Gets the state after the end of this block.
     */
    @Override
    public FrameState stateAfter() {
        return stateAfter;
    }

    public void setStateAfter(FrameState state) {
        stateAfter = state;
    }

    /**
     * Checks whether this instruction is a safepoint.
     * @return {@code true} if this instruction is a safepoint
     */
    public boolean isSafepoint() {
        return checkFlag(Value.Flag.IsSafepoint);
    }

    /**
     * Gets the block begin associated with this block end.
     * @return the beginning of this basic block
     */
    public BlockBegin begin() {
        return begin;
    }

    /**
     * Sets the basic block beginning for this block end. This should only
     * be called from {@link BlockBegin}.
     *
     * @param block the beginning of this basic block
     */
    void setBegin(BlockBegin block) {
        begin = block;
    }

    /**
     * Substitutes a successor block in this block end's successor list. Note that
     * this method updates all occurrences in the list.
     * @param oldSucc the old successor to replace
     * @param newSucc the new successor
     */
    public void substituteSuccessor(BlockBegin oldSucc, BlockBegin newSucc) {
        assert newSucc != null;
        Util.replaceAllInList(oldSucc, newSucc, successors);
    }

    /**
     * Gets the successor corresponding to the default (fall through) case.
     * @return the default successor
     */
    public BlockBegin defaultSuccessor() {
        return successors.get(successors.size() - 1);
    }

    /**
     * Searches for the specified successor and returns its index into the
     * successor list if found.
     * @param b the block to search for in the successor list
     * @return the index of the block in the list if found; <code>-1</code> otherwise
     */
    public int successorIndex(BlockBegin b) {
        final int max = successors.size();
        for (int i = 0; i < max; i++) {
            if (successors.get(i) == b) {
                return i;
            }
        }
        return -1;
    }

    /**
     * Gets this block end's list of successors.
     * @return the successor list
     */
    public List<BlockBegin> successors() {
        return successors;
    }

    /**
     * Gets the successor at a specified index.
     * @param index the index of the successor
     * @return the successor
     */
    public BlockBegin suxAt(int index) {
        return successors.get(index);
    }
}