/*

 * Copyright (c) 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

 * questions.

 */

package org.graalvm.compiler.hotspot.lir.test;

import java.util.ArrayList;

import java.util.List;

import org.graalvm.compiler.core.common.LIRKind;

import org.graalvm.compiler.hotspot.HotSpotBackend;

import org.graalvm.compiler.lir.VirtualStackSlot;

import org.graalvm.compiler.lir.framemap.FrameMapBuilder;

import org.graalvm.compiler.lir.gen.LIRGeneratorTool;

import org.graalvm.compiler.lir.jtt.LIRTest;

import org.graalvm.compiler.lir.jtt.LIRTestSpecification;

import org.graalvm.compiler.lir.stackslotalloc.LSStackSlotAllocator;

import org.graalvm.compiler.nodes.SafepointNode;

import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderConfiguration;

import org.graalvm.compiler.nodes.graphbuilderconf.GraphBuilderContext;

import org.graalvm.compiler.nodes.graphbuilderconf.InvocationPlugin;

import org.junit.Assume;

import org.junit.Test;

import jdk.vm.ci.meta.AllocatableValue;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.ResolvedJavaMethod;

/**

 * Tests the mitigation against overflowing the max size limit for a HotSpot OopMap. The mitigation

 * works by {@link LSStackSlotAllocator} placing reference typed stack slots at lower offsets.

 */

public class MitigateExceedingMaxOopMapStackOffsetTest extends LIRTest {

    /**

     * Allocate stacks slots and initializes those at an odd index with a reference constant and

     * those at an even index with a primitive constant.

     */

    private static class WriteStackValues extends LIRTestSpecification {

        private final JavaConstant objectConstant;

        private final JavaConstant primitiveConstant;

        WriteStackValues(JavaConstant objectConstant, JavaConstant primitiveConstant) {

            this.objectConstant = objectConstant;

            this.primitiveConstant = primitiveConstant;

        }

        @Override

        public void generate(LIRGeneratorTool gen) {

            FrameMapBuilder frameMapBuilder = gen.getResult().getFrameMapBuilder();

            LIRKind objectLirKind = LIRKind.reference(gen.target().arch.getPlatformKind(objectConstant.getJavaKind()));

            LIRKind primitiveLirKind = LIRKind.value(gen.target().arch.getPlatformKind(primitiveConstant.getJavaKind()));

            int numSlots = numPrimitiveSlots + numReferenceSlots;

            List<AllocatableValue> slotList = new ArrayList<>(numSlots);

            // Place reference slots at top and bottom of virtual frame

            // with primitive slots in the middle. This tests that slot

            // partitioning works.

            AllocatableValue srcObject = gen.emitLoadConstant(objectLirKind, objectConstant);

            for (int i = 0; i < numReferenceSlots / 2; i++) {

                VirtualStackSlot slot = frameMapBuilder.allocateSpillSlot(objectLirKind);

                slotList.add(slot);

                gen.emitMove(slot, srcObject);

            }

            AllocatableValue srcPrimitive = gen.emitLoadConstant(objectLirKind, primitiveConstant);

            for (int i = 0; i < numPrimitiveSlots; i++) {

                VirtualStackSlot slot = frameMapBuilder.allocateSpillSlot(primitiveLirKind);

                slotList.add(slot);

                gen.emitMove(slot, srcPrimitive);

            }

            for (int i = numReferenceSlots / 2; i < numReferenceSlots; i++) {

                VirtualStackSlot slot = frameMapBuilder.allocateSpillSlot(objectLirKind);

                slotList.add(slot);

                gen.emitMove(slot, srcObject);

            }

            slots = slotList.toArray(new AllocatableValue[slotList.size()]);

        }

    }

    /**

     * Read stacks slots and move their content into a blackhole.

     */

    private static class ReadStackValues extends LIRTestSpecification {

        ReadStackValues() {

        }

        @Override

        public void generate(LIRGeneratorTool gen) {

            for (int i = 0; i < slots.length; i++) {

                gen.emitBlackhole(gen.emitMove(slots[i]));

            }

        }

    }

    @Override

    protected GraphBuilderConfiguration editGraphBuilderConfiguration(GraphBuilderConfiguration conf) {

        InvocationPlugin safepointPlugin = new InvocationPlugin() {

            @Override

            public boolean apply(GraphBuilderContext b, ResolvedJavaMethod targetMethod, Receiver receiver) {

                b.add(new SafepointNode());

                return true;

            }

        };

        conf.getPlugins().getInvocationPlugins().register(safepointPlugin, getClass(), "safepoint");

        return super.editGraphBuilderConfiguration(conf);

    }

    /*

     * Safepoint Snippet

     */

    private static void safepoint() {

    }

    private static int numPrimitiveSlots;

    private static int numReferenceSlots;

    private static AllocatableValue[] slots;

    private static final LIRTestSpecification readStackValues = new ReadStackValues();

    @SuppressWarnings("unused")

    @LIRIntrinsic

    public static void instrinsic(LIRTestSpecification spec) {

    }

    private static final LIRTestSpecification writeStackValues = new WriteStackValues(JavaConstant.NULL_POINTER, JavaConstant.LONG_0);

    public void testStackObjects() {

        instrinsic(writeStackValues);

        safepoint();

        instrinsic(readStackValues);

    }

    @Test

    public void runStackObjects() {

        int max = ((HotSpotBackend) getBackend()).getRuntime().getVMConfig().maxOopMapStackOffset;

        Assume.assumeFalse("no limit on oop map size", max == Integer.MAX_VALUE);

        numPrimitiveSlots = (max / 8) * 2;

        numReferenceSlots = (max / 8) - 100; // Should be enough margin for all platforms

        runTest("testStackObjects");

    }

}