/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2005-2006 University of Maryland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package edu.umd.cs.findbugs.detect;
import java.util.BitSet;
import org.apache.bcel.classfile.Code;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.LocalVariableAnnotation;
import edu.umd.cs.findbugs.StatelessDetector;
public class FindLocalSelfAssignment2 extends BytecodeScanningDetector implements StatelessDetector {
private BugReporter bugReporter;
private int previousLoadOf = -1;
private int previousGotoTarget;
private int gotoCount;
public FindLocalSelfAssignment2(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
private BitSet previousStores = new BitSet();
@Override
public void visit(Code obj) {
previousLoadOf = -1;
previousGotoTarget = -1;
gotoCount = 0;
previousStores.clear();
super.visit(obj);
}
@Override
public void sawOpcode(int seen) {
if (seen == GOTO) {
previousGotoTarget = getBranchTarget();
gotoCount++;
if (previousGotoTarget < getPC())
previousLoadOf = -1;
} else {
if (isRegisterLoad())
previousLoadOf = getRegisterOperand();
else {
if (isRegisterStore()) {
if (previousLoadOf == getRegisterOperand() && gotoCount < 2 && getPC() != previousGotoTarget) {
int priority = NORMAL_PRIORITY;
String methodName = getMethodName();
if (methodName.equals("<init>") || methodName.startsWith("set") && getCode().getCode().length <= 5 ||
!previousStores.get(getRegisterOperand())) priority = HIGH_PRIORITY;
bugReporter.reportBug(
new BugInstance(this,
"SA_LOCAL_SELF_ASSIGNMENT", priority)
.addClassAndMethod(this)
.add(LocalVariableAnnotation.getLocalVariableAnnotation(getMethod(), getRegisterOperand(), getPC(), getPC()))
.addSourceLine(this));
}
previousStores.set(getRegisterOperand());
}
previousLoadOf = -1;
gotoCount = 0;
}
}
}
}