/*

 * Copyright (c) 2011, 2019, 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

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 */

package jdk.vm.ci.hotspot;

import jdk.vm.ci.meta.JavaMethodProfile;

import jdk.vm.ci.meta.JavaTypeProfile;

import jdk.vm.ci.meta.ProfilingInfo;

import jdk.vm.ci.meta.TriState;

/**

 * Base class for accessing the different kinds of data in a HotSpot {@code MethodData}. This is

 * similar to {@link ProfilingInfo}, but most methods require a {@link HotSpotMethodData} and the

 * exact position within the method data.

 */

abstract class HotSpotMethodDataAccessor {

    final int tag;

    final int staticSize;

    final HotSpotMethodData.VMState state;

    final HotSpotVMConfig config;

    protected HotSpotMethodDataAccessor(HotSpotMethodData.VMState state, int tag, int staticSize) {

        this.state = state;

        this.config = state.config;

        this.tag = tag;

        this.staticSize = staticSize;

    }

    /**

     * Returns the tag stored in the LayoutData header.

     *

     * @return tag stored in the LayoutData header

     */

    int getTag() {

        return tag;

    }

    static int readTag(HotSpotVMConfig config, HotSpotMethodData data, int position) {

        final int tag = data.readUnsignedByte(position, config.dataLayoutTagOffset);

        assert tag >= config.dataLayoutNoTag && tag <= config.dataLayoutSpeculativeTrapDataTag : "profile data tag out of bounds: " + tag;

        return tag;

    }

    /**

     * Returns the BCI stored in the LayoutData header.

     *

     * @return an integer between 0 and {@link Short#MAX_VALUE} inclusive, or -1 if not supported

     */

    int getBCI(HotSpotMethodData data, int position) {

        return data.readUnsignedShort(position, config.dataLayoutBCIOffset);

    }

    /**

     * Computes the size for the specific data at the given position.

     *

     * @return a value greater than 0

     */

    final int getSize(HotSpotMethodData data, int position) {

        int size = staticSize + getDynamicSize(data, position);

        // Sanity check against VM

        int vmSize = HotSpotJVMCIRuntime.runtime().compilerToVm.methodDataProfileDataSize(data.metaspaceMethodData, position);

        assert size == vmSize : size + " != " + vmSize;

        return size;

    }

    TriState getExceptionSeen(HotSpotMethodData data, int position) {

        final int exceptionsMask = 1 << config.bitDataExceptionSeenFlag;

        return TriState.get((getFlags(data, position) & exceptionsMask) != 0);

    }

    /**

     * @param data

     * @param position

     */

    JavaTypeProfile getTypeProfile(HotSpotMethodData data, int position) {

        return null;

    }

    /**

     * @param data

     * @param position

     */

    JavaMethodProfile getMethodProfile(HotSpotMethodData data, int position) {

        return null;

    }

    /**

     * @param data

     * @param position

     */

    double getBranchTakenProbability(HotSpotMethodData data, int position) {

        return -1;

    }

    /**

     * @param data

     * @param position

     */

    double[] getSwitchProbabilities(HotSpotMethodData data, int position) {

        return null;

    }

    /**

     * @param data

     * @param position

     */

    int getExecutionCount(HotSpotMethodData data, int position) {

        return -1;

    }

    /**

     * @param data

     * @param position

     */

    TriState getNullSeen(HotSpotMethodData data, int position) {

        return TriState.UNKNOWN;

    }

    protected int getFlags(HotSpotMethodData data, int position) {

        return data.readUnsignedByte(position, config.dataLayoutFlagsOffset);

    }

    /**

     * @param data

     * @param position

     */

    protected int getDynamicSize(HotSpotMethodData data, int position) {

        return 0;

    }

    abstract StringBuilder appendTo(StringBuilder sb, HotSpotMethodData data, int pos);

}