/*

 * Copyright (c) 2011, 2018, 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 jdk.vm.ci.hotspot;

import static jdk.vm.ci.hotspot.CompilerToVM.compilerToVM;

import static jdk.vm.ci.hotspot.HotSpotJVMCIRuntime.runtime;

import static jdk.vm.ci.hotspot.HotSpotVMConfig.config;

import static jdk.vm.ci.hotspot.UnsafeAccess.UNSAFE;

import java.lang.invoke.MethodHandle;

import jdk.vm.ci.common.JVMCIError;

import jdk.vm.ci.meta.ConstantPool;

import jdk.vm.ci.meta.JavaConstant;

import jdk.vm.ci.meta.JavaField;

import jdk.vm.ci.meta.JavaMethod;

import jdk.vm.ci.meta.JavaType;

import jdk.vm.ci.meta.ResolvedJavaMethod;

import jdk.vm.ci.meta.ResolvedJavaType;

import jdk.vm.ci.meta.Signature;

import jdk.vm.ci.meta.UnresolvedJavaField;

import jdk.vm.ci.meta.UnresolvedJavaMethod;

import jdk.vm.ci.meta.UnresolvedJavaType;

/**

 * Implementation of {@link ConstantPool} for HotSpot.

 */

public final class HotSpotConstantPool implements ConstantPool, MetaspaceWrapperObject {

    /**

     * Subset of JVM bytecode opcodes used by {@link HotSpotConstantPool}.

     */

    public static class Bytecodes {

        public static final int LDC = 18; // 0x12

        public static final int LDC_W = 19; // 0x13

        public static final int LDC2_W = 20; // 0x14

        public static final int GETSTATIC = 178; // 0xB2

        public static final int PUTSTATIC = 179; // 0xB3

        public static final int GETFIELD = 180; // 0xB4

        public static final int PUTFIELD = 181; // 0xB5

        public static final int INVOKEVIRTUAL = 182; // 0xB6

        public static final int INVOKESPECIAL = 183; // 0xB7

        public static final int INVOKESTATIC = 184; // 0xB8

        public static final int INVOKEINTERFACE = 185; // 0xB9

        public static final int INVOKEDYNAMIC = 186; // 0xBA

        public static final int NEW = 187; // 0xBB

        public static final int NEWARRAY = 188; // 0xBC

        public static final int ANEWARRAY = 189; // 0xBD

        public static final int CHECKCAST = 192; // 0xC0

        public static final int INSTANCEOF = 193; // 0xC1

        public static final int MULTIANEWARRAY = 197; // 0xC5

        static boolean isInvoke(int opcode) {

            switch (opcode) {

                case INVOKEVIRTUAL:

                case INVOKESPECIAL:

                case INVOKESTATIC:

                case INVOKEINTERFACE:

                case INVOKEDYNAMIC:

                    return true;

                default:

                    return false;

            }

        }

        /**

         * See: {@code Rewriter::maybe_rewrite_invokehandle}.

         */

        static boolean isInvokeHandleAlias(int opcode) {

            switch (opcode) {

                case INVOKEVIRTUAL:

                case INVOKESPECIAL:

                    return true;

                default:

                    return false;

            }

        }

    }

    /**

     * Enum of all {@code JVM_CONSTANT} constants used in the VM. This includes the public and

     * internal ones.

     */

    private enum JVM_CONSTANT {

        // @formatter:off

        Utf8(config().jvmConstantUtf8),

        Integer(config().jvmConstantInteger),

        Long(config().jvmConstantLong),

        Float(config().jvmConstantFloat),

        Double(config().jvmConstantDouble),

        Class(config().jvmConstantClass),

        UnresolvedClass(config().jvmConstantUnresolvedClass),

        UnresolvedClassInError(config().jvmConstantUnresolvedClassInError),

        String(config().jvmConstantString),

        Fieldref(config().jvmConstantFieldref),

        MethodRef(config().jvmConstantMethodref),

        InterfaceMethodref(config().jvmConstantInterfaceMethodref),

        NameAndType(config().jvmConstantNameAndType),

        MethodHandle(config().jvmConstantMethodHandle),

        MethodHandleInError(config().jvmConstantMethodHandleInError),

        MethodType(config().jvmConstantMethodType),

        MethodTypeInError(config().jvmConstantMethodTypeInError),

        InvokeDynamic(config().jvmConstantInvokeDynamic);

        // @formatter:on

        private final int tag;

        private static final int ExternalMax = config().jvmConstantExternalMax;

        private static final int InternalMin = config().jvmConstantInternalMin;

        private static final int InternalMax = config().jvmConstantInternalMax;

        JVM_CONSTANT(int tag) {

            this.tag = tag;

        }

        /**

         * Maps JVM_CONSTANT tags to {@link JVM_CONSTANT} values. Using a separate class for lazy

         * initialization.

         */

        static class TagValueMap {

            private static final JVM_CONSTANT[] table = new JVM_CONSTANT[ExternalMax + 1 + (InternalMax - InternalMin) + 1];

            static {

                assert InternalMin > ExternalMax;

                for (JVM_CONSTANT e : values()) {

                    table[indexOf(e.tag)] = e;

                }

            }

            private static int indexOf(int tag) {

                if (tag >= InternalMin) {

                    return tag - InternalMin + ExternalMax + 1;

                } else {

                    assert tag <= ExternalMax;

                }

                return tag;

            }

            static JVM_CONSTANT get(int tag) {

                JVM_CONSTANT res = table[indexOf(tag)];

                if (res != null) {

                    return res;

                }

                throw new JVMCIError("Unknown JVM_CONSTANT tag %s", tag);

            }

        }

        public static JVM_CONSTANT getEnum(int tag) {

            return TagValueMap.get(tag);

        }

    }

    private static class LookupTypeCacheElement {

        int lastCpi = Integer.MIN_VALUE;

        JavaType javaType;

        LookupTypeCacheElement(int lastCpi, JavaType javaType) {

            super();

            this.lastCpi = lastCpi;

            this.javaType = javaType;

        }

    }

    /**

     * Reference to the C++ ConstantPool object.

     */

    private final long metaspaceConstantPool;

    private volatile LookupTypeCacheElement lastLookupType;

    /**

     * Gets the JVMCI mirror from a HotSpot constant pool.The VM is responsible for ensuring that

     * the ConstantPool is kept alive for the duration of this call and the

     * {@link HotSpotJVMCIMetaAccessContext} keeps it alive after that.

     *

     * Called from the VM.

     *

     * @param metaspaceConstantPool a metaspace ConstantPool object

     * @return the {@link HotSpotConstantPool} corresponding to {@code metaspaceConstantPool}

     */

    @SuppressWarnings("unused")

    private static HotSpotConstantPool fromMetaspace(long metaspaceConstantPool) {

        HotSpotConstantPool cp = new HotSpotConstantPool(metaspaceConstantPool);

        runtime().metaAccessContext.add(cp);

        return cp;

    }

    private HotSpotConstantPool(long metaspaceConstantPool) {

        this.metaspaceConstantPool = metaspaceConstantPool;

    }

    /**

     * Gets the holder for this constant pool as {@link HotSpotResolvedObjectTypeImpl}.

     *

     * @return holder for this constant pool

     */

    private HotSpotResolvedObjectType getHolder() {

        return compilerToVM().getResolvedJavaType(this, config().constantPoolHolderOffset, false);

    }

    /**

     * Converts a raw index from the bytecodes to a constant pool cache index by adding a

     * {@link HotSpotVMConfig#constantPoolCpCacheIndexTag constant}.

     *

     * @param rawIndex index from the bytecode

     * @param opcode bytecode to convert the index for

     * @return constant pool cache index

     */

    private static int rawIndexToConstantPoolCacheIndex(int rawIndex, int opcode) {

        int index;

        if (opcode == Bytecodes.INVOKEDYNAMIC) {

            index = rawIndex;

            // See: ConstantPool::is_invokedynamic_index

            assert index < 0 : "not an invokedynamic constant pool index " + index;

        } else {

            assert opcode == Bytecodes.GETFIELD || opcode == Bytecodes.PUTFIELD || opcode == Bytecodes.GETSTATIC || opcode == Bytecodes.PUTSTATIC || opcode == Bytecodes.INVOKEINTERFACE ||

                            opcode == Bytecodes.INVOKEVIRTUAL || opcode == Bytecodes.INVOKESPECIAL || opcode == Bytecodes.INVOKESTATIC : "unexpected invoke opcode " + opcode;

            index = rawIndex + config().constantPoolCpCacheIndexTag;

        }

        return index;

    }

    /**

     * Decode a constant pool cache index to a constant pool index.

     *

     * See {@code ConstantPool::decode_cpcache_index}.

     *

     * @param index constant pool cache index

     * @return decoded index

     */

    private static int decodeConstantPoolCacheIndex(int index) {

        if (isInvokedynamicIndex(index)) {

            return decodeInvokedynamicIndex(index);

        } else {

            return index - config().constantPoolCpCacheIndexTag;

        }

    }

    /**

     * See {@code ConstantPool::is_invokedynamic_index}.

     */

    private static boolean isInvokedynamicIndex(int index) {

        return index < 0;

    }

    /**

     * See {@code ConstantPool::decode_invokedynamic_index}.

     */

    private static int decodeInvokedynamicIndex(int i) {

        assert isInvokedynamicIndex(i) : i;

        return ~i;

    }

    long getMetaspaceConstantPool() {

        return metaspaceConstantPool;

    }

    @Override

    public long getMetaspacePointer() {

        return getMetaspaceConstantPool();

    }

    /**

     * Gets the constant pool tag at index {@code index}.

     *

     * @param index constant pool index

     * @return constant pool tag

     */

    private JVM_CONSTANT getTagAt(int index) {

        assert checkBounds(index);

        HotSpotVMConfig config = config();

        final long metaspaceConstantPoolTags = UNSAFE.getAddress(getMetaspaceConstantPool() + config.constantPoolTagsOffset);

        final int tag = UNSAFE.getByteVolatile(null, metaspaceConstantPoolTags + config.arrayU1DataOffset + index);

        if (tag == 0) {

            return null;

        }

        return JVM_CONSTANT.getEnum(tag);

    }

    /**

     * Gets the constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return constant pool entry

     */

    long getEntryAt(int index) {

        assert checkBounds(index);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        return UNSAFE.getAddress(getMetaspaceConstantPool() + config().constantPoolSize + offset);

    }

    /**

     * Gets the integer constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return integer constant pool entry at index

     */

    private int getIntAt(int index) {

        assert checkTag(index, JVM_CONSTANT.Integer);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        return UNSAFE.getInt(getMetaspaceConstantPool() + config().constantPoolSize + offset);

    }

    /**

     * Gets the long constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return long constant pool entry

     */

    private long getLongAt(int index) {

        assert checkTag(index, JVM_CONSTANT.Long);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        return UNSAFE.getLong(getMetaspaceConstantPool() + config().constantPoolSize + offset);

    }

    /**

     * Gets the float constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return float constant pool entry

     */

    private float getFloatAt(int index) {

        assert checkTag(index, JVM_CONSTANT.Float);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        return UNSAFE.getFloat(getMetaspaceConstantPool() + config().constantPoolSize + offset);

    }

    /**

     * Gets the double constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return float constant pool entry

     */

    private double getDoubleAt(int index) {

        assert checkTag(index, JVM_CONSTANT.Double);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        return UNSAFE.getDouble(getMetaspaceConstantPool() + config().constantPoolSize + offset);

    }

    /**

     * Gets the {@code JVM_CONSTANT_NameAndType} constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return {@code JVM_CONSTANT_NameAndType} constant pool entry

     */

    private int getNameAndTypeAt(int index) {

        assert checkTag(index, JVM_CONSTANT.NameAndType);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        return UNSAFE.getInt(getMetaspaceConstantPool() + config().constantPoolSize + offset);

    }

    /**

     * Gets the {@code JVM_CONSTANT_NameAndType} reference index constant pool entry at index

     * {@code index}.

     *

     * @param index constant pool index

     * @return {@code JVM_CONSTANT_NameAndType} reference constant pool entry

     */

    private int getNameAndTypeRefIndexAt(int index) {

        return compilerToVM().lookupNameAndTypeRefIndexInPool(this, index);

    }

    /**

     * Gets the name of a {@code JVM_CONSTANT_NameAndType} constant pool entry referenced by another

     * entry denoted by {@code which}.

     *

     * @param which constant pool index or constant pool cache index

     * @return name as {@link String}

     */

    private String getNameOf(int which) {

        return compilerToVM().lookupNameInPool(this, which);

    }

    /**

     * Gets the name reference index of a {@code JVM_CONSTANT_NameAndType} constant pool entry at

     * index {@code index}.

     *

     * @param index constant pool index

     * @return name reference index

     */

    private int getNameRefIndexAt(int index) {

        final int refIndex = getNameAndTypeAt(index);

        // name ref index is in the low 16-bits.

        return refIndex & 0xFFFF;

    }

    /**

     * Gets the signature of a {@code JVM_CONSTANT_NameAndType} constant pool entry referenced by

     * another entry denoted by {@code which}.

     *

     * @param which constant pool index or constant pool cache index

     * @return signature as {@link String}

     */

    private String getSignatureOf(int which) {

        return compilerToVM().lookupSignatureInPool(this, which);

    }

    /**

     * Gets the signature reference index of a {@code JVM_CONSTANT_NameAndType} constant pool entry

     * at index {@code index}.

     *

     * @param index constant pool index

     * @return signature reference index

     */

    private int getSignatureRefIndexAt(int index) {

        final int refIndex = getNameAndTypeAt(index);

        // signature ref index is in the high 16-bits.

        return refIndex >>> 16;

    }

    /**

     * Gets the klass reference index constant pool entry at index {@code index}.

     *

     * @param index constant pool index

     * @return klass reference index

     */

    private int getKlassRefIndexAt(int index) {

        return compilerToVM().lookupKlassRefIndexInPool(this, index);

    }

    /**

     * Gets the uncached klass reference index constant pool entry at index {@code index}. See:

     * {@code ConstantPool::uncached_klass_ref_index_at}.

     *

     * @param index constant pool index

     * @return klass reference index

     */

    private int getUncachedKlassRefIndexAt(int index) {

        assert checkTagIsFieldOrMethod(index);

        int offset = index * runtime().getHostJVMCIBackend().getTarget().wordSize;

        final int refIndex = UNSAFE.getInt(getMetaspaceConstantPool() + config().constantPoolSize + offset);

        // klass ref index is in the low 16-bits.

        return refIndex & 0xFFFF;

    }

    /**

     * Checks that the constant pool index {@code index} is in the bounds of the constant pool.

     *

     * @param index constant pool index

     * @throws AssertionError if the check fails

     */

    private boolean checkBounds(int index) {

        assert 0 <= index && index < length() : "index " + index + " not between 0 and " + length();

        return true;

    }

    /**

     * Checks that the constant pool tag at index {@code index} is equal to {@code tag}.

     *

     * @param index constant pool index

     * @param tag expected tag

     * @throws AssertionError if the check fails

     */

    private boolean checkTag(int index, JVM_CONSTANT tag) {

        final JVM_CONSTANT tagAt = getTagAt(index);

        assert tagAt == tag : "constant pool tag at index " + index + " is " + tagAt + " but expected " + tag;

        return true;

    }

    /**

     * Asserts that the constant pool tag at index {@code index} is a {@link JVM_CONSTANT#Fieldref},

     * or a {@link JVM_CONSTANT#MethodRef}, or a {@link JVM_CONSTANT#InterfaceMethodref}.

     *

     * @param index constant pool index

     * @throws AssertionError if the check fails

     */

    private boolean checkTagIsFieldOrMethod(int index) {

        final JVM_CONSTANT tagAt = getTagAt(index);

        assert tagAt == JVM_CONSTANT.Fieldref || tagAt == JVM_CONSTANT.MethodRef || tagAt == JVM_CONSTANT.InterfaceMethodref : tagAt;

        return true;

    }

    @Override

    public int length() {

        return UNSAFE.getInt(getMetaspaceConstantPool() + config().constantPoolLengthOffset);

    }

    public boolean hasDynamicConstant() {

        return (flags() & config().constantPoolHasDynamicConstant) != 0;

    }

    private int flags() {

        return UNSAFE.getInt(getMetaspaceConstantPool() + config().constantPoolFlagsOffset);

    }

    @Override

    public Object lookupConstant(int cpi) {

        assert cpi != 0;

        final JVM_CONSTANT tag = getTagAt(cpi);

        switch (tag) {

            case Integer:

                return JavaConstant.forInt(getIntAt(cpi));

            case Long:

                return JavaConstant.forLong(getLongAt(cpi));

            case Float:

                return JavaConstant.forFloat(getFloatAt(cpi));

            case Double:

                return JavaConstant.forDouble(getDoubleAt(cpi));

            case Class:

            case UnresolvedClass:

            case UnresolvedClassInError:

                final int opcode = -1;  // opcode is not used

                return lookupType(cpi, opcode);

            case String:

                /*

                 * "pseudo strings" (arbitrary live objects) patched into a String entry. Such