/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2004-2006 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.HashMap;
import java.util.LinkedList;
import java.util.Map;
import org.apache.bcel.classfile.Code;
import org.objectweb.asm.Opcodes;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.SourceLineAnnotation;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;
public class RepeatedConditionals extends OpcodeStackDetector {
BugReporter bugReporter;
public RepeatedConditionals(BugReporter bugReporter) {
this.bugReporter = bugReporter;
reset();
}
@Override
public void visit(Code code) {
boolean interesting = true;
if (interesting) {
// initialize any variables we want to initialize for the method
super.visit(code); // make callbacks to sawOpcode for all opcodes
reset();
}
}
/*
* (non-Javadoc)
*
* @see edu.umd.cs.findbugs.bcel.OpcodeStackDetector#sawOpcode(int)
*/
int oldPC;
LinkedList<Integer> emptyStackLocations = new LinkedList<Integer>();
LinkedList<Integer> prevOpcodeLocations = new LinkedList<Integer>();
Map<Integer, Integer> branchTargets = new HashMap<Integer, Integer>();
@Override
public void sawBranchTo(int pc) {
branchTargets.put(getPC(), pc);
}
@Override
public void sawOpcode(int seen) {
if (isRegisterStore() || isReturn(seen) || isSwitch(seen) || seen == INVOKEINTERFACE || seen == INVOKESPECIAL
|| seen == INVOKESTATIC || seen == INVOKEVIRTUAL || seen == PUTFIELD || seen == PUTSTATIC) {
reset();
} else if (stack.getStackDepth() == 0) {
check: if (emptyStackLocations.size() > 1) {
int first = emptyStackLocations.get(emptyStackLocations.size() - 2);
int second = emptyStackLocations.get(emptyStackLocations.size() - 1);
int third = getPC();
if (third - second == second - first) {
int endOfFirstSegment = prevOpcodeLocations.get(emptyStackLocations.size() - 1);
int endOfSecondSegment = oldPC;
int opcodeAtEndOfFirst = getCodeByte(endOfFirstSegment);
int opcodeAtEndOfSecond = getCodeByte(endOfSecondSegment);
if (!isBranch(opcodeAtEndOfFirst) || !isBranch(opcodeAtEndOfSecond)) {
break check;
}
if (opcodeAtEndOfFirst == Opcodes.GOTO || opcodeAtEndOfSecond == Opcodes.GOTO) {
break check;
}
if (opcodeAtEndOfFirst != opcodeAtEndOfSecond
&& !areOppositeBranches(opcodeAtEndOfFirst, opcodeAtEndOfSecond)) {
break check;
}
byte[] code = getCode().getCode();
if (first == endOfFirstSegment) {
break check;
}
for (int i = first; i < endOfFirstSegment; i++) {
if (code[i] != code[i - first + second]) {
break check;
}
}
if (false) {
System.out.println(getFullyQualifiedMethodName());
System.out.println(first + " ... " + endOfFirstSegment + " : " + OPCODE_NAMES[opcodeAtEndOfFirst]);
System.out.println(second + " ... " + endOfSecondSegment + " : " + OPCODE_NAMES[opcodeAtEndOfSecond]);
}
SourceLineAnnotation firstSourceLine = SourceLineAnnotation.fromVisitedInstructionRange(getClassContext(),
this, first, endOfFirstSegment - 1);
SourceLineAnnotation secondSourceLine = SourceLineAnnotation.fromVisitedInstructionRange(getClassContext(),
this, second, endOfSecondSegment - 1);
int priority = HIGH_PRIORITY;
if (firstSourceLine.getStartLine() == -1 || firstSourceLine.getStartLine() != secondSourceLine.getEndLine()) {
priority++;
}
if (stack.isJumpTarget(second)) {
priority++;
}
Integer firstTarget = branchTargets.get(endOfFirstSegment);
Integer secondTarget = branchTargets.get(endOfSecondSegment);
if (firstTarget == null || secondTarget == null) {
break check;
}
if (firstTarget.equals(secondTarget) && opcodeAtEndOfFirst == opcodeAtEndOfSecond
|| firstTarget.intValue() == getPC()) {
// identical checks;
} else {
// opposite checks
priority += 2;
}
BugInstance bug = new BugInstance(this, "RpC_REPEATED_CONDITIONAL_TEST", priority).addClassAndMethod(this)
.add(firstSourceLine).add(secondSourceLine);
bugReporter.reportBug(bug);
}
}
emptyStackLocations.add(getPC());
prevOpcodeLocations.add(oldPC);
}
oldPC = getPC();
}
private void reset() {
emptyStackLocations.clear();
prevOpcodeLocations.clear();
branchTargets.clear();
oldPC = -1;
}
}