/*
 * Copyright (c) 2018, 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 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.UnsafeAccess.UNSAFE;

import java.lang.annotation.Annotation;
import java.lang.reflect.Array;
import java.lang.reflect.Executable;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.HashMap;

import jdk.vm.ci.common.JVMCIError;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.MetaAccessProvider;
import jdk.vm.ci.meta.ResolvedJavaField;
import jdk.vm.ci.meta.ResolvedJavaMethod;
import jdk.vm.ci.meta.ResolvedJavaType;

Implementation of HotSpotJVMCIReflection in terms of standard JDK reflection API. This is only available when running in the HotSpot heap. /**
 * Implementation of {@link HotSpotJVMCIReflection} in terms of standard JDK reflection API. This is
 * only available when running in the HotSpot heap.
 */
final class HotSpotJDKReflection extends HotSpotJVMCIReflection {

    @Override
    Object resolveObject(HotSpotObjectConstantImpl object) {
        if (object == null) {
            return null;
        }
        return ((DirectHotSpotObjectConstantImpl) object).object;
    }

    @Override
    boolean isInstance(HotSpotResolvedObjectTypeImpl holder, HotSpotObjectConstantImpl obj) {
        Class<?> javaMirror = getMirror(holder);
        Object value = resolveObject(obj);
        return javaMirror.isInstance(value);
    }

    @Override
    boolean isAssignableFrom(HotSpotResolvedObjectTypeImpl holder, HotSpotResolvedObjectTypeImpl otherType) {
        Class<?> javaMirror = getMirror(holder);
        return javaMirror.isAssignableFrom(getMirror(otherType));

    }

    @Override
    Annotation[] getAnnotations(HotSpotResolvedObjectTypeImpl holder) {
        Class<?> javaMirror = getMirror(holder);
        return javaMirror.getAnnotations();
    }

    @Override
    Annotation[] getDeclaredAnnotations(HotSpotResolvedObjectTypeImpl holder) {
        Class<?> javaMirror = getMirror(holder);
        return javaMirror.getDeclaredAnnotations();
    }

    @Override
    <T extends Annotation> T getAnnotation(HotSpotResolvedObjectTypeImpl holder, Class<T> annotationClass) {
        Class<?> javaMirror = getMirror(holder);
        return javaMirror.getAnnotation(annotationClass);
    }

    @Override
    boolean isLocalClass(HotSpotResolvedObjectTypeImpl holder) {
        Class<?> javaMirror = getMirror(holder);
        return javaMirror.isLocalClass();
    }

    @Override
    boolean isMemberClass(HotSpotResolvedObjectTypeImpl holder) {
        Class<?> javaMirror = getMirror(holder);
        return javaMirror.isMemberClass();
    }

    @Override
    HotSpotResolvedObjectType getEnclosingClass(HotSpotResolvedObjectTypeImpl holder) {
        Class<?> javaMirror = getMirror(holder);
        return (HotSpotResolvedObjectType) runtime().fromClass(javaMirror.getEnclosingClass());
    }

    @Override
    JavaConstant readFieldValue(HotSpotResolvedObjectTypeImpl holder, HotSpotResolvedJavaField field, boolean isVolatile) {
        Class<?> javaMirror = getMirror(holder);
        return readFieldValue(field, javaMirror, isVolatile);
    }

    @Override
    JavaConstant readFieldValue(HotSpotObjectConstantImpl object, HotSpotResolvedJavaField field, boolean isVolatile) {
        Object value = resolveObject(object);
        return readFieldValue(field, value, isVolatile);
    }

    @Override
    boolean equals(HotSpotObjectConstantImpl a, HotSpotObjectConstantImpl b) {
        return resolveObject(a) == resolveObject(b) && a.isCompressed() == b.isCompressed();
    }

    @Override
    JavaConstant getJavaMirror(HotSpotResolvedPrimitiveType holder) {
        return holder.mirror;
    }

    @Override
    ResolvedJavaMethod.Parameter[] getParameters(HotSpotResolvedJavaMethodImpl javaMethod) {
        java.lang.reflect.Parameter[] javaParameters = getMethod(javaMethod).getParameters();
        ResolvedJavaMethod.Parameter[] res = new ResolvedJavaMethod.Parameter[javaParameters.length];
        for (int i = 0; i < res.length; i++) {
            java.lang.reflect.Parameter src = javaParameters[i];
            String paramName = src.isNamePresent() ? src.getName() : null;
            res[i] = new ResolvedJavaMethod.Parameter(paramName, src.getModifiers(), javaMethod, i);
        }
        return res;
    }

    @Override
    Annotation[][] getParameterAnnotations(HotSpotResolvedJavaMethodImpl javaMethod) {
        return getMethod(javaMethod).getParameterAnnotations();
    }

    @Override
    Type[] getGenericParameterTypes(HotSpotResolvedJavaMethodImpl javaMethod) {
        return getMethod(javaMethod).getGenericParameterTypes();
    }

    @Override
    Annotation[] getFieldAnnotations(HotSpotResolvedJavaFieldImpl javaField) {
        return getField(javaField).getAnnotations();
    }

    @Override
    Annotation[] getMethodAnnotations(HotSpotResolvedJavaMethodImpl javaMethod) {
        return getMethod(javaMethod).getAnnotations();
    }

    @Override
    Annotation[] getMethodDeclaredAnnotations(HotSpotResolvedJavaMethodImpl javaMethod) {
        return getMethod(javaMethod).getDeclaredAnnotations();
    }

    @Override
    Annotation[] getFieldDeclaredAnnotations(HotSpotResolvedJavaFieldImpl javaField) {
        return getField(javaField).getDeclaredAnnotations();
    }

    @Override
    <T extends Annotation> T getMethodAnnotation(HotSpotResolvedJavaMethodImpl javaMethod, Class<T> annotationClass) {
        return getMethod(javaMethod).getAnnotation(annotationClass);
    }

    @Override
    <T extends Annotation> T getFieldAnnotation(HotSpotResolvedJavaFieldImpl javaField, Class<T> annotationClass) {
        return getField(javaField).getAnnotation(annotationClass);
    }

    @Override
    HotSpotResolvedObjectTypeImpl getType(HotSpotObjectConstantImpl object) {
        Object value = resolveObject(object);
        Class<?> theClass = value.getClass();
        return (HotSpotResolvedObjectTypeImpl) runtime().fromClass(theClass);
    }

    @Override
    String asString(HotSpotObjectConstantImpl object) {
        Object value = resolveObject(object);
        if (value instanceof String) {
            return (String) value;
        }
        return null;
    }

    @Override
    ResolvedJavaType asJavaType(HotSpotObjectConstantImpl object) {
        Object value = resolveObject(object);
        if (value instanceof Class) {
            Class<?> javaClass = (Class<?>) value;
            return runtime().fromClass(javaClass);
        }
        if (value instanceof ResolvedJavaType) {
            return (ResolvedJavaType) value;
        }
        return null;
    }

    @SuppressWarnings("unchecked")
    @Override
    <T> T asObject(HotSpotObjectConstantImpl object, Class<T> type) {
        Object value = resolveObject(object);
        if (type.isInstance(value)) {
            return (T) value;
        }
        return null;
    }

    @Override
    Object asObject(HotSpotObjectConstantImpl object, HotSpotResolvedJavaType type) {
        Object value = resolveObject(object);
        if (getMirror(type).isInstance(value)) {
            return value;
        }
        return null;
    }

    @Override
    String formatString(HotSpotObjectConstantImpl object) {
        return JavaKind.Object.format(resolveObject(object));
    }

    @Override
    Integer getLength(HotSpotObjectConstantImpl arrayObject) {
        Object object = resolveObject(arrayObject);
        if (object.getClass().isArray()) {
            return Array.getLength(object);
        }
        return null;
    }

    @Override
    JavaConstant readArrayElement(HotSpotObjectConstantImpl arrayObject, int index) {
        Object a = resolveObject(arrayObject);
        if (!a.getClass().isArray() || index < 0 || index >= Array.getLength(a)) {
            return null;
        }
        if (a instanceof Object[]) {
            Object element = ((Object[]) a)[index];
            return forObject(element);
        } else {
            if (a instanceof int[]) {
                return JavaConstant.forInt(((int[]) a)[index]);
            } else if (a instanceof char[]) {
                return JavaConstant.forChar(((char[]) a)[index]);
            } else if (a instanceof byte[]) {
                return JavaConstant.forByte(((byte[]) a)[index]);
            } else if (a instanceof long[]) {
                return JavaConstant.forLong(((long[]) a)[index]);
            } else if (a instanceof short[]) {
                return JavaConstant.forShort(((short[]) a)[index]);
            } else if (a instanceof float[]) {
                return JavaConstant.forFloat(((float[]) a)[index]);
            } else if (a instanceof double[]) {
                return JavaConstant.forDouble(((double[]) a)[index]);
            } else if (a instanceof boolean[]) {
                return JavaConstant.forBoolean(((boolean[]) a)[index]);
            } else {
                throw new JVMCIError("Should not reach here");
            }
        }
    }

    @Override
    JavaConstant unboxPrimitive(HotSpotObjectConstantImpl source) {
        return JavaConstant.forBoxedPrimitive(resolveObject(source));
    }

    @Override
    JavaConstant forObject(Object value) {
        if (value == null) {
            return JavaConstant.NULL_POINTER;
        }
        return forNonNullObject(value);
    }

    private static HotSpotObjectConstantImpl forNonNullObject(Object value) {
        return DirectHotSpotObjectConstantImpl.forNonNullObject(value, false);
    }

    @Override
    JavaConstant boxPrimitive(JavaConstant source) {
        return forNonNullObject(source.asBoxedPrimitive());
    }

    @Override
    int getInt(HotSpotObjectConstantImpl object, long displacement) {
        return UNSAFE.getInt((resolveObject(object)), displacement);
    }

    @Override
    byte getByte(HotSpotObjectConstantImpl object, long displacement) {
        return UNSAFE.getByte(resolveObject(object), displacement);
    }

    @Override
    short getShort(HotSpotObjectConstantImpl object, long displacement) {
        return UNSAFE.getShort(resolveObject(object), displacement);
    }

    @Override
    long getLong(HotSpotObjectConstantImpl object, long displacement) {
        return UNSAFE.getLong(resolveObject(object), displacement);
    }

    @Override
    void checkRead(HotSpotObjectConstantImpl constant, JavaKind kind, long displacement, HotSpotResolvedObjectType type) {
        checkRead(kind, displacement, type, resolveObject(constant));
    }

    
Offset of injected java.lang.Class::oop_size field. No need to make volatile as initialization is idempotent. /**
     * Offset of injected {@code java.lang.Class::oop_size} field. No need to make {@code volatile}
     * as initialization is idempotent.
     */
    private long oopSizeOffset;

    private static int computeOopSizeOffset(HotSpotJVMCIRuntime runtime) {
        MetaAccessProvider metaAccess = runtime.getHostJVMCIBackend().getMetaAccess();
        ResolvedJavaType staticType = metaAccess.lookupJavaType(Class.class);
        for (ResolvedJavaField f : staticType.getInstanceFields(false)) {
            if (f.getName().equals("oop_size")) {
                int offset = f.getOffset();
                assert offset != 0 : "not expecting offset of java.lang.Class::oop_size to be 0";
                return offset;
            }
        }
        throw new JVMCIError("Could not find injected java.lang.Class::oop_size field");
    }

    long oopSizeOffset() {
        if (oopSizeOffset == 0) {
            oopSizeOffset = computeOopSizeOffset(runtime());
        }
        return oopSizeOffset;
    }

    private boolean checkRead(JavaKind kind, long displacement, HotSpotResolvedObjectType type, Object object) {
        if (type.isArray()) {
            ResolvedJavaType componentType = type.getComponentType();
            JavaKind componentKind = componentType.getJavaKind();
            final int headerSize = runtime().getArrayBaseOffset(componentKind);
            int sizeOfElement = runtime().getArrayIndexScale(componentKind);
            int length = Array.getLength(object);
            long arrayEnd = headerSize + (sizeOfElement * length);
            boolean aligned = ((displacement - headerSize) % sizeOfElement) == 0;
            if (displacement < 0 || displacement > (arrayEnd - sizeOfElement) || (kind == JavaKind.Object && !aligned)) {
                int index = (int) ((displacement - headerSize) / sizeOfElement);
                throw new IllegalArgumentException("Unsafe array access: reading element of kind " + kind +
                                " at offset " + displacement + " (index ~ " + index + ") in " +
                                type.toJavaName() + " object of length " + length);
            }
        } else if (kind != JavaKind.Object) {
            long size;
            if (object instanceof Class) {
                int wordSize = runtime().getHostJVMCIBackend().getCodeCache().getTarget().wordSize;
                size = UNSAFE.getInt(object, oopSizeOffset()) * wordSize;
            } else {
                size = Math.abs(type.instanceSize());
            }
            int bytesToRead = kind.getByteCount();
            if (displacement + bytesToRead > size || displacement < 0) {
                throw new IllegalArgumentException("Unsafe access: reading " + bytesToRead + " bytes at offset " + displacement + " in " +
                                type.toJavaName() + " object of size " + size);
            }
        } else {
            ResolvedJavaField field = null;
            if (object instanceof Class) {
                // Read of a static field
                HotSpotResolvedJavaType hotSpotResolvedJavaType = runtime().fromClass((Class<?>) object);
                if (hotSpotResolvedJavaType instanceof HotSpotResolvedObjectTypeImpl) {
                    HotSpotResolvedObjectTypeImpl staticFieldsHolder = (HotSpotResolvedObjectTypeImpl) hotSpotResolvedJavaType;
                    field = staticFieldsHolder.findStaticFieldWithOffset(displacement, JavaKind.Object);
                }
            }
            if (field == null) {
                field = type.findInstanceFieldWithOffset(displacement, JavaKind.Object);
            }
            if (field == null) {
                throw new IllegalArgumentException("Unsafe object access: field not found for read of kind Object" +
                                " at offset " + displacement + " in " + type.toJavaName() + " object");
            }
            if (field.getJavaKind() != JavaKind.Object) {
                throw new IllegalArgumentException("Unsafe object access: field " + field.format("%H.%n:%T") + " not of expected kind Object" +
                                " at offset " + displacement + " in " + type.toJavaName() + " object");
            }
        }
        return true;
    }

    JavaConstant readFieldValue(HotSpotResolvedJavaField field, Object obj, boolean isVolatile) {
        assert obj != null;
        assert !field.isStatic() || obj instanceof Class;
        long displacement = field.getOffset();

        assert checkRead(field.getJavaKind(), displacement,
                        (HotSpotResolvedObjectType) runtime().getHostJVMCIBackend().getMetaAccess().lookupJavaType(field.isStatic() ? (Class<?>) obj : obj.getClass()),
                        obj);
        JavaKind kind = field.getJavaKind();
        switch (kind) {
            case Boolean:
                return JavaConstant.forBoolean(isVolatile ? UNSAFE.getBooleanVolatile(obj, displacement) : UNSAFE.getBoolean(obj, displacement));
            case Byte:
                return JavaConstant.forByte(isVolatile ? UNSAFE.getByteVolatile(obj, displacement) : UNSAFE.getByte(obj, displacement));
            case Char:
                return JavaConstant.forChar(isVolatile ? UNSAFE.getCharVolatile(obj, displacement) : UNSAFE.getChar(obj, displacement));
            case Short:
                return JavaConstant.forShort(isVolatile ? UNSAFE.getShortVolatile(obj, displacement) : UNSAFE.getShort(obj, displacement));
            case Int:
                return JavaConstant.forInt(isVolatile ? UNSAFE.getIntVolatile(obj, displacement) : UNSAFE.getInt(obj, displacement));
            case Long:
                return JavaConstant.forLong(isVolatile ? UNSAFE.getLongVolatile(obj, displacement) : UNSAFE.getLong(obj, displacement));
            case Float:
                return JavaConstant.forFloat(isVolatile ? UNSAFE.getFloatVolatile(obj, displacement) : UNSAFE.getFloat(obj, displacement));
            case Double:
                return JavaConstant.forDouble(isVolatile ? UNSAFE.getDoubleVolatile(obj, displacement) : UNSAFE.getDouble(obj, displacement));
            case Object:
                return forObject(isVolatile ? UNSAFE.getReferenceVolatile(obj, displacement) : UNSAFE.getReference(obj, displacement));
            default:
                throw new IllegalArgumentException("Unsupported kind: " + kind);

        }
    }

    
Gets a Method object corresponding to method. This method guarantees the same Method object is returned if called twice on the same method value. /**
     * Gets a {@link Method} object corresponding to {@code method}. This method guarantees the same
     * {@link Method} object is returned if called twice on the same {@code method} value.
     */
    private static Executable getMethod(HotSpotResolvedJavaMethodImpl method) {
        assert !method.isClassInitializer() : method;
        if (method.toJavaCache == null) {
            synchronized (method) {
                if (method.toJavaCache == null) {
                    method.toJavaCache = compilerToVM().asReflectionExecutable(method);
                }
            }
        }
        return method.toJavaCache;
    }

    
Gets a Field object corresponding to field. This method guarantees the same Field object is returned if called twice on the same field value. This is required to ensure the results of HotSpotResolvedJavaFieldImpl.getAnnotations() and HotSpotResolvedJavaFieldImpl.getAnnotation(Class<Annotation>) are stable (i.e., for a given field f and annotation class a, the same object is returned for each call to f.getAnnotation(a)). /**
     * Gets a {@link Field} object corresponding to {@code field}. This method guarantees the same
     * {@link Field} object is returned if called twice on the same {@code field} value. This is
     * required to ensure the results of {@link HotSpotResolvedJavaFieldImpl#getAnnotations()} and
     * {@link HotSpotResolvedJavaFieldImpl#getAnnotation(Class)} are stable (i.e., for a given field
     * {@code f} and annotation class {@code a}, the same object is returned for each call to
     * {@code f.getAnnotation(a)}).
     */
    private static Field getField(HotSpotResolvedJavaFieldImpl field) {
        HotSpotResolvedObjectTypeImpl declaringClass = field.getDeclaringClass();
        synchronized (declaringClass) {
            HashMap<HotSpotResolvedJavaFieldImpl, Field> cache = declaringClass.reflectionFieldCache;
            if (cache == null) {
                cache = new HashMap<>();
                declaringClass.reflectionFieldCache = cache;
            }
            Field reflect = cache.get(field);
            if (reflect == null) {
                reflect = compilerToVM().asReflectionField(field.getDeclaringClass(), field.getIndex());
                cache.put(field, reflect);
            }
            return reflect;
        }
    }

    Class<?> getMirror(HotSpotResolvedObjectTypeImpl holder) {
        return (Class<?>) resolveObject((HotSpotObjectConstantImpl) holder.getJavaMirror());
    }

    Class<?> getMirror(HotSpotResolvedJavaType type) {
        assert type != null;
        if (type instanceof HotSpotResolvedPrimitiveType) {
            return (Class<?>) resolveObject(((HotSpotResolvedPrimitiveType) type).mirror);
        } else {
            return getMirror((HotSpotResolvedObjectTypeImpl) type);
        }
    }
}