/*
 * Copyright (c) 2012, 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.oracle.graal.hotspot.replacements;

import static com.oracle.graal.api.code.DeoptimizationAction.*;
import static com.oracle.graal.api.meta.DeoptimizationReason.*;
import static com.oracle.graal.hotspot.replacements.HotSpotSnippetUtils.*;
import static com.oracle.graal.hotspot.replacements.TypeCheckSnippetUtils.*;
import static com.oracle.graal.nodes.extended.UnsafeCastNode.*;
import static com.oracle.graal.replacements.SnippetTemplate.*;
import static com.oracle.graal.replacements.SnippetTemplate.Arguments.*;
import static com.oracle.graal.replacements.nodes.BranchProbabilityNode.*;

import com.oracle.graal.api.code.*;
import com.oracle.graal.api.meta.*;
import com.oracle.graal.debug.*;
import com.oracle.graal.graph.Node.NodeIntrinsic;
import com.oracle.graal.hotspot.meta.*;
import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.java.*;
import com.oracle.graal.nodes.spi.*;
import com.oracle.graal.nodes.type.*;
import com.oracle.graal.phases.*;
import com.oracle.graal.replacements.*;
import com.oracle.graal.replacements.Snippet.*;
import com.oracle.graal.replacements.nodes.*;
import com.oracle.graal.word.*;

/**
 * Snippets used for implementing the type test of a checkcast instruction.
 * 
 * The type tests implemented are described in the paper <a
 * href="http://dl.acm.org/citation.cfm?id=583821"> Fast subtype checking in the HotSpot JVM</a> by
 * Cliff Click and John Rose.
 */
public class CheckCastSnippets implements Snippets {

    @NodeIntrinsic(BreakpointNode.class)
    static native void bkpt(Object object, Word hub, Word objectHub);

    // @formatter:off

    /**
     * Type test used when the type being tested against is a final type.
     */
    @Snippet
    public static Object checkcastExact(
                    @Parameter("object") Object object,
                    @Parameter("exactHub") Word exactHub,
                    @ConstantParameter("checkNull") boolean checkNull) {
        if (checkNull && object == null) {
            probability(NOT_FREQUENT_PROBABILITY);
            isNull.inc();
        } else {
            Word objectHub = loadHub(object);
            if (objectHub.notEqual(exactHub)) {
                probability(DEOPT_PATH_PROBABILITY);
                exactMiss.inc();
                //bkpt(object, exactHub, objectHub);
                DeoptimizeNode.deopt(InvalidateReprofile, ClassCastException);
            }
            exactHit.inc();
        }
        /* make sure that the unsafeCast is done *after* the check above,
         * cf. ReadAfterCheckCast */
        BeginNode anchorNode = BeginNode.anchor(StampFactory.forNodeIntrinsic());
        return unsafeCast(verifyOop(object), StampFactory.forNodeIntrinsic(), anchorNode);
    }

    /**
     * Type test used when the type being tested against is a restricted primary type.
     *
     * This test ignores use of hints altogether as the display-based type check only
     * involves one extra load where the second load should hit the same cache line as the
     * first.
     */
    @Snippet
    public static Object checkcastPrimary(
                    @Parameter("hub") Word hub,
                    @Parameter("object") Object object,
                    @ConstantParameter("checkNull") boolean checkNull,
                    @ConstantParameter("superCheckOffset") int superCheckOffset) {
        if (checkNull && object == null) {
            probability(NOT_FREQUENT_PROBABILITY);
            isNull.inc();
        } else {
            Word objectHub = loadHub(object);
            if (objectHub.readWord(superCheckOffset, FINAL_LOCATION).notEqual(hub)) {
                probability(DEOPT_PATH_PROBABILITY);
                displayMiss.inc();
                DeoptimizeNode.deopt(InvalidateReprofile, ClassCastException);
            }
            displayHit.inc();
        }
        BeginNode anchorNode = BeginNode.anchor(StampFactory.forNodeIntrinsic());
        return unsafeCast(verifyOop(object), StampFactory.forNodeIntrinsic(), anchorNode);
    }

    /**
     * Type test used when the type being tested against is a restricted secondary type.
     */
    @Snippet
    public static Object checkcastSecondary(
                    @Parameter("hub") Word hub,
                    @Parameter("object") Object object,
                    @VarargsParameter("hints") Word[] hints,
                    @ConstantParameter("checkNull") boolean checkNull) {
        if (checkNull && object == null) {
            probability(NOT_FREQUENT_PROBABILITY);
            isNull.inc();
        } else {
            Word objectHub = loadHub(object);
            // if we get an exact match: succeed immediately
            ExplodeLoopNode.explodeLoop();
            for (int i = 0; i < hints.length; i++) {
                Word hintHub = hints[i];
                if (hintHub.equal(objectHub)) {
                    hintsHit.inc();
                    BeginNode anchorNode = BeginNode.anchor(StampFactory.forNodeIntrinsic());
                    return unsafeCast(verifyOop(object), StampFactory.forNodeIntrinsic(), anchorNode);
                }
            }
            if (!checkSecondarySubType(hub, objectHub)) {
                DeoptimizeNode.deopt(InvalidateReprofile, ClassCastException);
            }
        }
        BeginNode anchorNode = BeginNode.anchor(StampFactory.forNodeIntrinsic());
        return unsafeCast(verifyOop(object), StampFactory.forNodeIntrinsic(), anchorNode);
    }

    /**
     * Type test used when the type being tested against is not known at compile time (e.g. the type test
     * in an object array store check).
     */
    @Snippet
    public static Object checkcastDynamic(
                    @Parameter("hub") Word hub,
                    @Parameter("object") Object object,
                    @ConstantParameter("checkNull") boolean checkNull) {
        if (checkNull && object == null) {
            probability(NOT_FREQUENT_PROBABILITY);
            isNull.inc();
        } else {
            Word objectHub = loadHub(object);
            if (!checkUnknownSubType(hub, objectHub)) {
                DeoptimizeNode.deopt(InvalidateReprofile, ClassCastException);
            }
        }
        BeginNode anchorNode = BeginNode.anchor(StampFactory.forNodeIntrinsic());
        return unsafeCast(verifyOop(object), StampFactory.forNodeIntrinsic(), anchorNode);
    }

    // @formatter:on

    public static class Templates extends AbstractTemplates<CheckCastSnippets> {

        private final ResolvedJavaMethod exact;
        private final ResolvedJavaMethod primary;
        private final ResolvedJavaMethod secondary;
        private final ResolvedJavaMethod dynamic;

        public Templates(CodeCacheProvider runtime, Replacements replacements, TargetDescription target) {
            super(runtime, replacements, target, CheckCastSnippets.class);
            exact = snippet("checkcastExact", Object.class, Word.class, boolean.class);
            primary = snippet("checkcastPrimary", Word.class, Object.class, boolean.class, int.class);
            secondary = snippet("checkcastSecondary", Word.class, Object.class, Word[].class, boolean.class);
            dynamic = snippet("checkcastDynamic", Word.class, Object.class, boolean.class);
        }

        /**
         * Lowers a checkcast node.
         */
        public void lower(CheckCastNode checkcast, LoweringTool tool) {
            StructuredGraph graph = (StructuredGraph) checkcast.graph();
            ValueNode object = checkcast.object();
            final HotSpotResolvedObjectType type = (HotSpotResolvedObjectType) checkcast.type();
            TypeCheckHints hintInfo = new TypeCheckHints(checkcast.type(), checkcast.profile(), tool.assumptions(), GraalOptions.CheckcastMinHintHitProbability, GraalOptions.CheckcastMaxHints);
            ValueNode hub = ConstantNode.forConstant(type.klass(), runtime, checkcast.graph());
            boolean checkNull = !object.stamp().nonNull();
            Arguments arguments;
            Key key;

            assert type != null;
            if (hintInfo.exact) {
                ConstantNode[] hints = createHints(hintInfo, runtime, true, graph).hubs;
                assert hints.length == 1;
                key = new Key(exact).add("checkNull", checkNull);
                arguments = arguments("object", object).add("exactHub", hints[0]);
            } else if (type.isPrimaryType()) {
                key = new Key(primary).add("checkNull", checkNull).add("superCheckOffset", type.superCheckOffset());
                arguments = arguments("hub", hub).add("object", object);
            } else {
                ConstantNode[] hints = createHints(hintInfo, runtime, true, graph).hubs;
                key = new Key(secondary).add("hints", Varargs.vargargs(new Word[hints.length], StampFactory.forKind(wordKind()))).add("checkNull", checkNull);
                arguments = arguments("hub", hub).add("object", object).add("hints", hints);
            }

            SnippetTemplate template = cache.get(key);
            Debug.log("Lowering checkcast in %s: node=%s, template=%s, arguments=%s", graph, checkcast, template, arguments);
            template.instantiate(runtime, checkcast, DEFAULT_REPLACER, arguments);
        }

        /**
         * Lowers a dynamic checkcast node.
         */
        public void lower(CheckCastDynamicNode checkcast) {
            StructuredGraph graph = (StructuredGraph) checkcast.graph();
            ValueNode hub = checkcast.type();
            ValueNode object = checkcast.object();
            boolean checkNull = !object.stamp().nonNull();

            Key key = new Key(dynamic).add("checkNull", checkNull);
            Arguments arguments = arguments("hub", hub).add("object", object);

            SnippetTemplate template = cache.get(key);
            Debug.log("Lowering dynamic checkcast in %s: node=%s, template=%s, arguments=%s", graph, checkcast, template, arguments);
            template.instantiate(runtime, checkcast, DEFAULT_REPLACER, arguments);
        }
    }
}