/*
 * 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.CompilerToVM.compilerToVM;
import jdk.vm.ci.code.InstalledCode;
import jdk.vm.ci.code.InvalidInstalledCodeException;
import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.JavaType;
import jdk.vm.ci.meta.ResolvedJavaMethod;

Implementation of InstalledCode for code installed as an nmethod. The nmethod stores a weak reference to an instance of this class. This is necessary to keep the nmethod from being unloaded while the associated HotSpotNmethod instance is alive. 
 Note that there is no (current) way for the reference from an nmethod to a HotSpotNmethod instance to be anything but weak. This is due to the fact that HotSpot does not treat nmethods as strong GC roots. /**
 * Implementation of {@link InstalledCode} for code installed as an nmethod. The nmethod stores a
 * weak reference to an instance of this class. This is necessary to keep the nmethod from being
 * unloaded while the associated {@link HotSpotNmethod} instance is alive.
 * <p>
 * Note that there is no (current) way for the reference from an nmethod to a {@link HotSpotNmethod}
 * instance to be anything but weak. This is due to the fact that HotSpot does not treat nmethods as
 * strong GC roots.
 */
public class HotSpotNmethod extends HotSpotInstalledCode {

    
This (indirect) Method* reference is safe since class redefinition preserves all methods
associated with nmethods in the code cache.
/**
     * This (indirect) Method* reference is safe since class redefinition preserves all methods
     * associated with nmethods in the code cache.
     */
    private final HotSpotResolvedJavaMethod method;

    private final boolean isDefault;

    public HotSpotNmethod(HotSpotResolvedJavaMethod method, String name, boolean isDefault) {
        super(name);
        this.method = method;
        this.isDefault = isDefault;
    }

    public boolean isDefault() {
        return isDefault;
    }

    public ResolvedJavaMethod getMethod() {
        return method;
    }

    @Override
    public void invalidate() {
        compilerToVM().invalidateInstalledCode(this);
    }

    @Override
    public String toString() {
        return String.format("InstalledNmethod[method=%s, codeBlob=0x%x, isDefault=%b, name=%s]", method, getAddress(), isDefault, name);
    }

    protected boolean checkThreeObjectArgs() {
        assert method.getSignature().getParameterCount(!method.isStatic()) == 3;
        assert method.getSignature().getParameterKind(0) == JavaKind.Object;
        assert method.getSignature().getParameterKind(1) == JavaKind.Object;
        assert !method.isStatic() || method.getSignature().getParameterKind(2) == JavaKind.Object;
        return true;
    }

    private boolean checkArgs(Object... args) {
        JavaType[] sig = method.toParameterTypes();
        assert args.length == sig.length : method.format("%H.%n(%p): expected ") + sig.length + " args, got " + args.length;
        for (int i = 0; i < sig.length; i++) {
            Object arg = args[i];
            if (arg == null) {
                assert sig[i].getJavaKind() == JavaKind.Object : method.format("%H.%n(%p): expected arg ") + i + " to be Object, not " + sig[i];
            } else if (sig[i].getJavaKind() != JavaKind.Object) {
                assert sig[i].getJavaKind().toBoxedJavaClass() == arg.getClass() : method.format("%H.%n(%p): expected arg ") + i + " to be " + sig[i] + ", not " + arg.getClass();
            }
        }
        return true;
    }

    @Override
    public Object executeVarargs(Object... args) throws InvalidInstalledCodeException {
        assert checkArgs(args);
        return compilerToVM().executeInstalledCode(args, this);
    }

    @Override
    public long getStart() {
        return isValid() ? super.getStart() : 0;
    }
}