Mercurial > hg > Members > kono > jpf-core
view src/main/gov/nasa/jpf/jvm/bytecode/INVOKECLINIT.java @ 0:61d41facf527
initial v8 import (history reset)
author | Peter Mehlitz <Peter.C.Mehlitz@nasa.gov> |
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date | Fri, 23 Jan 2015 10:14:01 -0800 |
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children | 6774e2e08d37 |
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/* * Copyright (C) 2014, United States Government, as represented by the * Administrator of the National Aeronautics and Space Administration. * All rights reserved. * * The Java Pathfinder core (jpf-core) platform is licensed under the * Apache License, Version 2.0 (the "License"); you may not use this file except * in compliance with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0. * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package gov.nasa.jpf.jvm.bytecode; import gov.nasa.jpf.vm.ClassInfo; import gov.nasa.jpf.vm.ElementInfo; import gov.nasa.jpf.vm.Instruction; import gov.nasa.jpf.vm.MethodInfo; import gov.nasa.jpf.vm.ThreadInfo; /** * this is an artificial bytecode that we use to deal with the particularities of * <clinit> calls, which are never in the loaded bytecode but always directly called by * the VM. The most obvious difference is that <clinit> execution does not trigger * class initialization. * A more subtle difference is that we save a wait() - if a class * is concurrently initialized, both enter INVOKECLINIT (i.e. compete and sync for/on * the class object lock), but once the second thread gets resumed and detects that the * class is now initialized (by the first thread), it skips the method execution and * returns right away (after deregistering as a lock contender). That's kind of hackish, * but we have no method to do the wait in, unless we significantly complicate the * direct call stubs, which would obfuscate observability (debugging dynamically * generated code isn't very appealing). */ public class INVOKECLINIT extends INVOKESTATIC { public INVOKECLINIT (ClassInfo ci){ super(ci.getSignature(), "<clinit>", "()V"); } @Override public Instruction execute (ThreadInfo ti) { MethodInfo callee = getInvokedMethod(ti); ClassInfo ciClsObj = callee.getClassInfo(); ElementInfo ei = ciClsObj.getClassObject(); if (ciClsObj.isInitialized()) { // somebody might have already done it if this is re-executed if (ei.isRegisteredLockContender(ti)){ ei = ei.getModifiableInstance(); ei.unregisterLockContender(ti); } return getNext(); } // not much use to update sharedness, clinits are automatically synchronized if (reschedulesLockAcquisition(ti, ei)){ // this blocks or registers as lock contender return this; } // if we get here we still have to execute the clinit method setupCallee( ti, callee); // this creates, initializes & pushes the callee StackFrame, then acquires the lock return ti.getPC(); // we can't just return the first callee insn if a listener throws an exception } @Override public boolean isExtendedInstruction() { return true; } public static final int OPCODE = 256; @Override public int getByteCode () { return OPCODE; } @Override public void accept(JVMInstructionVisitor insVisitor) { insVisitor.visit(this); } }