| /* |
| * Copyright (c) 2011, 2015, 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.HotSpotConstantReflectionProvider.Options.*; |
| |
| import java.lang.reflect.*; |
| |
| import jdk.vm.ci.meta.*; |
| import jdk.vm.ci.options.*; |
| |
| /** |
| * HotSpot implementation of {@link ConstantReflectionProvider}. |
| */ |
| public class HotSpotConstantReflectionProvider implements ConstantReflectionProvider, HotSpotProxified { |
| |
| static class Options { |
| //@formatter:off |
| @Option(help = "Constant fold final fields with default values.", type = OptionType.Debug) |
| public static final OptionValue<Boolean> TrustFinalDefaultFields = new OptionValue<>(true); |
| //@formatter:on |
| } |
| |
| protected final HotSpotJVMCIRuntimeProvider runtime; |
| protected final HotSpotMethodHandleAccessProvider methodHandleAccess; |
| protected final HotSpotMemoryAccessProviderImpl memoryAccess; |
| |
| public HotSpotConstantReflectionProvider(HotSpotJVMCIRuntimeProvider runtime) { |
| this.runtime = runtime; |
| this.methodHandleAccess = new HotSpotMethodHandleAccessProvider(this); |
| this.memoryAccess = new HotSpotMemoryAccessProviderImpl(runtime); |
| } |
| |
| public MethodHandleAccessProvider getMethodHandleAccess() { |
| return methodHandleAccess; |
| } |
| |
| @Override |
| public MemoryAccessProvider getMemoryAccessProvider() { |
| return memoryAccess; |
| } |
| |
| @Override |
| public boolean isEmbeddable(Constant constant) { |
| return true; |
| } |
| |
| @Override |
| public Boolean constantEquals(Constant x, Constant y) { |
| if (x == y) { |
| return true; |
| } else if (x instanceof HotSpotObjectConstantImpl) { |
| return y instanceof HotSpotObjectConstantImpl && ((HotSpotObjectConstantImpl) x).object() == ((HotSpotObjectConstantImpl) y).object(); |
| } else { |
| return x.equals(y); |
| } |
| } |
| |
| @Override |
| public Integer readArrayLength(JavaConstant array) { |
| if (array.getJavaKind() != JavaKind.Object || array.isNull()) { |
| return null; |
| } |
| |
| Object arrayObject = ((HotSpotObjectConstantImpl) array).object(); |
| if (!arrayObject.getClass().isArray()) { |
| return null; |
| } |
| return Array.getLength(arrayObject); |
| } |
| |
| public JavaConstant readConstantArrayElement(JavaConstant array, int index) { |
| if (array instanceof HotSpotObjectConstantImpl && ((HotSpotObjectConstantImpl) array).getStableDimension() > 0) { |
| JavaConstant element = readArrayElement(array, index); |
| if (element != null && (((HotSpotObjectConstantImpl) array).isDefaultStable() || !element.isDefaultForKind())) { |
| return element; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Try to convert {@code offset} into an an index into {@code array}. |
| * |
| * @return the computed index or -1 if the offset isn't within the array |
| */ |
| private int indexForOffset(JavaConstant array, long offset) { |
| if (array.getJavaKind() != JavaKind.Object || array.isNull()) { |
| return -1; |
| } |
| Class<?> componentType = ((HotSpotObjectConstantImpl) array).object().getClass().getComponentType(); |
| JavaKind kind = runtime.getHostJVMCIBackend().getMetaAccess().lookupJavaType(componentType).getJavaKind(); |
| int arraybase = runtime.getArrayBaseOffset(kind); |
| int scale = runtime.getArrayIndexScale(kind); |
| if (offset < arraybase) { |
| return -1; |
| } |
| long index = offset - arraybase; |
| if (index % scale != 0) { |
| return -1; |
| } |
| long result = index / scale; |
| if (result >= Integer.MAX_VALUE) { |
| return -1; |
| } |
| return (int) result; |
| } |
| |
| public JavaConstant readConstantArrayElementForOffset(JavaConstant array, long offset) { |
| if (array instanceof HotSpotObjectConstantImpl && ((HotSpotObjectConstantImpl) array).getStableDimension() > 0) { |
| return readConstantArrayElement(array, indexForOffset(array, offset)); |
| } |
| return null; |
| } |
| |
| @Override |
| public JavaConstant readArrayElement(JavaConstant array, int index) { |
| if (array.getJavaKind() != JavaKind.Object || array.isNull()) { |
| return null; |
| } |
| Object a = ((HotSpotObjectConstantImpl) array).object(); |
| |
| if (index < 0 || index >= Array.getLength(a)) { |
| return null; |
| } |
| |
| if (a instanceof Object[]) { |
| Object element = ((Object[]) a)[index]; |
| if (((HotSpotObjectConstantImpl) array).getStableDimension() > 1) { |
| return HotSpotObjectConstantImpl.forStableArray(element, ((HotSpotObjectConstantImpl) array).getStableDimension() - 1, ((HotSpotObjectConstantImpl) array).isDefaultStable()); |
| } else { |
| return HotSpotObjectConstantImpl.forObject(element); |
| } |
| } else { |
| return JavaConstant.forBoxedPrimitive(Array.get(a, index)); |
| } |
| } |
| |
| /** |
| * Check if the constant is a boxed value that is guaranteed to be cached by the platform. |
| * Otherwise the generated code might be the only reference to the boxed value and since object |
| * references from nmethods are weak this can cause GC problems. |
| * |
| * @param source |
| * @return true if the box is cached |
| */ |
| private static boolean isBoxCached(JavaConstant source) { |
| switch (source.getJavaKind()) { |
| case Boolean: |
| return true; |
| case Char: |
| return source.asInt() <= 127; |
| case Byte: |
| case Short: |
| case Int: |
| return source.asInt() >= -128 && source.asInt() <= 127; |
| case Long: |
| return source.asLong() >= -128 && source.asLong() <= 127; |
| case Float: |
| case Double: |
| return false; |
| default: |
| throw new IllegalArgumentException("unexpected kind " + source.getJavaKind()); |
| } |
| } |
| |
| @Override |
| public JavaConstant boxPrimitive(JavaConstant source) { |
| if (!source.getJavaKind().isPrimitive() || !isBoxCached(source)) { |
| return null; |
| } |
| return HotSpotObjectConstantImpl.forObject(source.asBoxedPrimitive()); |
| } |
| |
| @Override |
| public JavaConstant unboxPrimitive(JavaConstant source) { |
| if (!source.getJavaKind().isObject()) { |
| return null; |
| } |
| if (source.isNull()) { |
| return null; |
| } |
| return JavaConstant.forBoxedPrimitive(((HotSpotObjectConstantImpl) source).object()); |
| } |
| |
| public JavaConstant forString(String value) { |
| return HotSpotObjectConstantImpl.forObject(value); |
| } |
| |
| @Override |
| public ResolvedJavaType asJavaType(Constant constant) { |
| if (constant instanceof HotSpotObjectConstant) { |
| Object obj = ((HotSpotObjectConstantImpl) constant).object(); |
| if (obj instanceof Class) { |
| return runtime.getHostJVMCIBackend().getMetaAccess().lookupJavaType((Class<?>) obj); |
| } |
| } |
| if (constant instanceof HotSpotMetaspaceConstant) { |
| Object obj = HotSpotMetaspaceConstantImpl.getMetaspaceObject(constant); |
| if (obj instanceof HotSpotResolvedObjectTypeImpl) { |
| return (ResolvedJavaType) obj; |
| } |
| } |
| return null; |
| } |
| |
| private static final String SystemClassName = "Ljava/lang/System;"; |
| |
| /** |
| * Determines if a static field is constant for the purpose of |
| * {@link #readConstantFieldValue(JavaField, JavaConstant)}. |
| */ |
| protected boolean isStaticFieldConstant(HotSpotResolvedJavaField staticField) { |
| if (staticField.isFinal() || staticField.isStable()) { |
| ResolvedJavaType holder = staticField.getDeclaringClass(); |
| if (holder.isInitialized() && !holder.getName().equals(SystemClassName)) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /** |
| * Determines if a value read from a {@code final} instance field is considered constant. The |
| * implementation in {@link HotSpotConstantReflectionProvider} returns true if {@code value} is |
| * not the {@link JavaConstant#isDefaultForKind default value} for its kind or if |
| * {@link Options#TrustFinalDefaultFields} is true. |
| * |
| * @param value a value read from a {@code final} instance field |
| * @param receiverClass the {@link Object#getClass() class} of object from which the |
| * {@code value} was read |
| */ |
| protected boolean isFinalInstanceFieldValueConstant(JavaConstant value, Class<?> receiverClass) { |
| return !value.isDefaultForKind() || TrustFinalDefaultFields.getValue(); |
| } |
| |
| /** |
| * Determines if a value read from a {@link Stable} instance field is considered constant. The |
| * implementation in {@link HotSpotConstantReflectionProvider} returns true if {@code value} is |
| * not the {@link JavaConstant#isDefaultForKind default value} for its kind. |
| * |
| * @param value a value read from a {@link Stable} field |
| * @param receiverClass the {@link Object#getClass() class} of object from which the |
| * {@code value} was read |
| */ |
| protected boolean isStableInstanceFieldValueConstant(JavaConstant value, Class<?> receiverClass) { |
| return !value.isDefaultForKind(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * <p> |
| * The {@code value} field in {@link OptionValue} is considered constant if the type of |
| * {@code receiver} is (assignable to) {@link StableOptionValue}. |
| */ |
| public JavaConstant readConstantFieldValue(JavaField field, JavaConstant receiver) { |
| HotSpotResolvedJavaField hotspotField = (HotSpotResolvedJavaField) field; |
| |
| if (hotspotField.isStatic()) { |
| if (isStaticFieldConstant(hotspotField)) { |
| JavaConstant value = readFieldValue(field, receiver); |
| if (hotspotField.isFinal() || !value.isDefaultForKind()) { |
| return value; |
| } |
| } |
| } else { |
| /* |
| * for non-static final fields, we must assume that they are only initialized if they |
| * have a non-default value. |
| */ |
| Object object = receiver.isNull() ? null : ((HotSpotObjectConstantImpl) receiver).object(); |
| |
| // Canonicalization may attempt to process an unsafe read before |
| // processing a guard (e.g. a null check or a type check) for this read |
| // so we need to check the object being read |
| if (object != null) { |
| if (hotspotField.isFinal()) { |
| if (hotspotField.isInObject(object)) { |
| JavaConstant value = readFieldValue(field, receiver); |
| if (isFinalInstanceFieldValueConstant(value, object.getClass())) { |
| return value; |
| } |
| } |
| } else if (hotspotField.isStable()) { |
| if (hotspotField.isInObject(object)) { |
| JavaConstant value = readFieldValue(field, receiver); |
| if (isStableInstanceFieldValueConstant(value, object.getClass())) { |
| return value; |
| } |
| } |
| } else { |
| Class<?> clazz = object.getClass(); |
| if (StableOptionValue.class.isAssignableFrom(clazz)) { |
| if (hotspotField.isInObject(object) && hotspotField.getName().equals("value")) { |
| StableOptionValue<?> option = (StableOptionValue<?>) object; |
| return HotSpotObjectConstantImpl.forObject(option.getValue()); |
| } |
| } |
| } |
| } |
| } |
| return null; |
| } |
| |
| public JavaConstant readFieldValue(JavaField field, JavaConstant receiver) { |
| HotSpotResolvedJavaField hotspotField = (HotSpotResolvedJavaField) field; |
| if (!hotspotField.isStable()) { |
| return readNonStableFieldValue(field, receiver); |
| } else { |
| return readStableFieldValue(field, receiver, false); |
| } |
| } |
| |
| private JavaConstant readNonStableFieldValue(JavaField field, JavaConstant receiver) { |
| HotSpotResolvedJavaField hotspotField = (HotSpotResolvedJavaField) field; |
| if (hotspotField.isStatic()) { |
| HotSpotResolvedJavaType holder = (HotSpotResolvedJavaType) hotspotField.getDeclaringClass(); |
| if (holder.isInitialized()) { |
| return memoryAccess.readUnsafeConstant(hotspotField.getJavaKind(), HotSpotObjectConstantImpl.forObject(holder.mirror()), hotspotField.offset()); |
| } |
| } else { |
| if (receiver.isNonNull() && hotspotField.isInObject(((HotSpotObjectConstantImpl) receiver).object())) { |
| return memoryAccess.readUnsafeConstant(hotspotField.getJavaKind(), receiver, hotspotField.offset()); |
| } |
| } |
| return null; |
| } |
| |
| public JavaConstant readStableFieldValue(JavaField field, JavaConstant receiver, boolean isDefaultStable) { |
| JavaConstant fieldValue = readNonStableFieldValue(field, receiver); |
| if (fieldValue.isNonNull()) { |
| JavaType declaredType = field.getType(); |
| if (declaredType.getComponentType() != null) { |
| int stableDimension = getArrayDimension(declaredType); |
| return HotSpotObjectConstantImpl.forStableArray(((HotSpotObjectConstantImpl) fieldValue).object(), stableDimension, isDefaultStable); |
| } |
| } |
| return fieldValue; |
| } |
| |
| private static int getArrayDimension(JavaType type) { |
| int dimensions = 0; |
| JavaType componentType = type; |
| while ((componentType = componentType.getComponentType()) != null) { |
| dimensions++; |
| } |
| return dimensions; |
| } |
| } |
