--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.jvmci.hotspot/src/com/oracle/jvmci/hotspot/HotSpotConstantReflectionProvider.java	Tue May 26 17:13:37 2015 +0200
@@ -0,0 +1,364 @@
+/*
+ * 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 com.oracle.jvmci.hotspot;
+
+import static com.oracle.jvmci.hotspot.HotSpotConstantReflectionProvider.Options.*;
+
+import java.lang.reflect.*;
+
+import com.oracle.graal.api.meta.*;
+import com.oracle.graal.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 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.getKind() != Kind.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 -1 if the offset isn't within the array or the computed index
+     */
+    private int indexForOffset(JavaConstant array, long offset) {
+        if (array.getKind() != Kind.Object || array.isNull()) {
+            return -1;
+        }
+        Class<?> componentType = ((HotSpotObjectConstantImpl) array).object().getClass().getComponentType();
+        Kind kind = runtime.getHostJVMCIBackend().getMetaAccess().lookupJavaType(componentType).getKind();
+        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.getKind() != Kind.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.getKind()) {
+            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.getKind());
+        }
+    }
+
+    @Override
+    public JavaConstant boxPrimitive(JavaConstant source) {
+        if (!source.getKind().isPrimitive() || !isBoxCached(source)) {
+            return null;
+        }
+        return HotSpotObjectConstantImpl.forObject(source.asBoxedPrimitive());
+    }
+
+    @Override
+    public JavaConstant unboxPrimitive(JavaConstant source) {
+        if (!source.getKind().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.getKind(), HotSpotObjectConstantImpl.forObject(holder.mirror()), hotspotField.offset());
+            }
+        } else {
+            if (receiver.isNonNull() && hotspotField.isInObject(((HotSpotObjectConstantImpl) receiver).object())) {
+                return memoryAccess.readUnsafeConstant(hotspotField.getKind(), 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;
+    }
+}