001/*
002 * Copyright (c) 2014, 2015, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package jdk.internal.jvmci.hotspot;
024
025import static jdk.internal.jvmci.common.UnsafeAccess.*;
026import static jdk.internal.jvmci.hotspot.HotSpotJVMCIRuntime.*;
027
028import jdk.internal.jvmci.common.*;
029import sun.misc.*;
030
031/**
032 * Class to access the C++ {@code vmSymbols} table.
033 */
034public final class HotSpotVmSymbols {
035
036    /**
037     * Returns the symbol in the {@code vmSymbols} table at position {@code index} as {@link String}
038     * .
039     *
040     * @param index position in the symbol table
041     * @return the symbol at position id
042     */
043    public static String symbolAt(int index) {
044        HotSpotJVMCIRuntimeProvider runtime = runtime();
045        HotSpotVMConfig config = runtime.getConfig();
046        assert config.vmSymbolsFirstSID <= index && index < config.vmSymbolsSIDLimit : "index " + index + " is out of bounds";
047        assert config.symbolPointerSize == Unsafe.ADDRESS_SIZE : "the following address read is broken";
048        final long metaspaceSymbol = unsafe.getAddress(config.vmSymbolsSymbols + index * config.symbolPointerSize);
049        if (HotSpotConstantPool.Options.UseConstantPoolCacheJavaCode.getValue()) {
050            HotSpotSymbol symbol = new HotSpotSymbol(metaspaceSymbol);
051            String s = symbol.asString();
052            // It shouldn't but just in case something went wrong...
053            if (s == null) {
054                throw JVMCIError.shouldNotReachHere("malformed UTF-8 string in constant pool");
055            }
056            return s;
057        } else {
058            return runtime.getCompilerToVM().getSymbol(metaspaceSymbol);
059        }
060    }
061}