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An auxiliary findbugs.sourceforge.net plugin for java bug detectors that fall outside the narrow scope of detectors to be packaged with the product itself.
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/*
* fb-contrib - Auxiliary detectors for Java programs
* Copyright (C) 2005-2019 Dave Brosius
*
* 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 com.mebigfatguy.fbcontrib.detect;
import org.apache.bcel.Const;
import org.apache.bcel.classfile.Code;
import com.mebigfatguy.fbcontrib.collect.MethodInfo;
import com.mebigfatguy.fbcontrib.collect.Statistics;
import com.mebigfatguy.fbcontrib.utils.BugType;
import com.mebigfatguy.fbcontrib.utils.SignatureUtils;
import com.mebigfatguy.fbcontrib.utils.Values;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.BytecodeScanningDetector;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.OpcodeStack.CustomUserValue;
import edu.umd.cs.findbugs.ba.ClassContext;
/**
* looks for conditional expressions where both simple local variable
* (in)equalities are used along with method calls, where the method calls are
* done first. By placing the simple local checks first, you eliminate
* potentially costly calls in some cases. This assumes that the methods called
* won't have side-effects that are desired. At present it only looks for simple
* sequences of 'and' based conditions.
*/
@CustomUserValue
public class SuboptimalExpressionOrder extends BytecodeScanningDetector {
private static final int NORMAL_WEIGHT_LIMIT = 50;
private BugReporter bugReporter;
private OpcodeStack stack;
private int conditionalTarget;
private int sawMethodWeight;
/**
* constructs a SEO detector given the reporter to report bugs on
*
* @param bugReporter the sync of bug reports
*/
public SuboptimalExpressionOrder(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
/**
* overrides the visitor to setup the opcode stack
*
* @param clsContext the context object of the currently parse class
*/
@Override
public void visitClassContext(ClassContext clsContext) {
try {
stack = new OpcodeStack();
super.visitClassContext(clsContext);
} finally {
stack = null;
}
}
/**
* overrides the visitor to reset the opcode stack, and initialize vars
*
* @param obj the code object of the currently parsed method
*/
@Override
public void visitCode(Code obj) {
stack.resetForMethodEntry(this);
conditionalTarget = -1;
sawMethodWeight = 0;
super.visitCode(obj);
}
/**
* overrides the visitor to look for chains of expressions joined by 'and' that
* have method calls before simple local variable conditions
*
* @param seen the currently parse opcode
*/
@Override
public void sawOpcode(int seen) {
Integer userValue = null;
if ((conditionalTarget != -1) && (getPC() >= conditionalTarget)) {
conditionalTarget = -1;
sawMethodWeight = 0;
}
try {
switch (seen) {
case Const.INVOKESPECIAL:
case Const.INVOKESTATIC:
case Const.INVOKEINTERFACE:
case Const.INVOKEVIRTUAL:
String signature = getSigConstantOperand();
if (Values.SIG_VOID.equals(SignatureUtils.getReturnSignature(signature))) {
sawMethodWeight = 0;
return;
}
for (String parmSig : SignatureUtils.getParameterSignatures(signature)) {
if (parmSig.charAt(0) == '[') {
sawMethodWeight = 0;
return;
}
}
String clsName = getClassConstantOperand();
MethodInfo mi = Statistics.getStatistics().getMethodStatistics(clsName, getNameConstantOperand(),
signature);
if ((mi == null) || (mi.getNumBytes() == 0)) {
userValue = Values.ONE;
} else {
userValue = Integer.valueOf(mi.getNumBytes());
}
break;
case Const.LCMP:
case Const.FCMPL:
case Const.FCMPG:
case Const.DCMPL:
case Const.DCMPG:
case Const.IAND:
case Const.IOR:
case Const.IXOR:
if (stack.getStackDepth() >= 2) {
for (int i = 0; i <= 1; i++) {
OpcodeStack.Item itm = stack.getStackItem(i);
userValue = (Integer) itm.getUserValue();
if (userValue != null) {
break;
}
}
} else {
sawMethodWeight = 0;
}
break;
case Const.IF_ICMPEQ:
case Const.IF_ICMPNE:
case Const.IF_ICMPLT:
case Const.IF_ICMPGE:
case Const.IF_ICMPGT:
case Const.IF_ICMPLE:
case Const.IF_ACMPEQ:
case Const.IF_ACMPNE:
if (conditionalTarget < 0) {
conditionalTarget = getBranchTarget();
} else if (conditionalTarget != getBranchTarget()) {
conditionalTarget = -1;
sawMethodWeight = 0;
return;
}
if (stack.getStackDepth() >= 2) {
int expWeight = 0;
for (int i = 0; i <= 1; i++) {
OpcodeStack.Item itm = stack.getStackItem(i);
Integer uv = (Integer) itm.getUserValue();
if (uv != null) {
expWeight = Math.max(uv.intValue(), expWeight);
}
}
if ((expWeight == 0) && (sawMethodWeight > 0)) {
bugReporter.reportBug(new BugInstance(this, BugType.SEO_SUBOPTIMAL_EXPRESSION_ORDER.name(),
sawMethodWeight >= NORMAL_WEIGHT_LIMIT ? NORMAL_PRIORITY : LOW_PRIORITY).addClass(this)
.addMethod(this).addSourceLine(this));
sawMethodWeight = 0;
conditionalTarget = Integer.MAX_VALUE;
} else {
sawMethodWeight = Math.max(sawMethodWeight, expWeight);
}
}
break;
case Const.IFEQ:
case Const.IFNE:
case Const.IFLT:
case Const.IFGE:
case Const.IFGT:
case Const.IFLE:
case Const.IFNULL:
case Const.IFNONNULL:
if (conditionalTarget < 0) {
conditionalTarget = getBranchTarget();
} else if (conditionalTarget != getBranchTarget()) {
conditionalTarget = -1;
sawMethodWeight = 0;
return;
}
if (stack.getStackDepth() >= 1) {
OpcodeStack.Item itm = stack.getStackItem(0);
Integer uv = (Integer) itm.getUserValue();
if (uv == null) {
if (sawMethodWeight > 0) {
bugReporter.reportBug(new BugInstance(this, BugType.SEO_SUBOPTIMAL_EXPRESSION_ORDER.name(),
sawMethodWeight >= NORMAL_WEIGHT_LIMIT ? NORMAL_PRIORITY : LOW_PRIORITY)
.addClass(this).addMethod(this).addSourceLine(this));
sawMethodWeight = 0;
conditionalTarget = Integer.MAX_VALUE;
}
} else {
sawMethodWeight = Math.max(sawMethodWeight, uv.intValue());
}
}
break;
case Const.ISTORE:
case Const.LSTORE:
case Const.FSTORE:
case Const.DSTORE:
case Const.ASTORE:
case Const.ISTORE_0:
case Const.ISTORE_1:
case Const.ISTORE_2:
case Const.ISTORE_3:
case Const.LSTORE_0:
case Const.LSTORE_1:
case Const.LSTORE_2:
case Const.LSTORE_3:
case Const.FSTORE_0:
case Const.FSTORE_1:
case Const.FSTORE_2:
case Const.FSTORE_3:
case Const.DSTORE_0:
case Const.DSTORE_1:
case Const.DSTORE_2:
case Const.DSTORE_3:
case Const.ASTORE_0:
case Const.ASTORE_1:
case Const.ASTORE_2:
case Const.ASTORE_3:
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
itm.setUserValue(null);
}
sawMethodWeight = 0;
conditionalTarget = -1;
break;
case Const.ATHROW:
case Const.POP:
case Const.POP2:
case Const.GOTO:
case Const.GOTO_W:
case Const.PUTFIELD:
case Const.PUTSTATIC:
case Const.IINC:
case Const.INSTANCEOF:
case Const.RETURN:
case Const.ARETURN:
case Const.IRETURN:
case Const.LRETURN:
case Const.FRETURN:
case Const.DRETURN:
sawMethodWeight = 0;
conditionalTarget = -1;
break;
case Const.ARRAYLENGTH:
case Const.CHECKCAST:
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
userValue = (Integer) itm.getUserValue();
}
break;
case Const.GETFIELD:
if (stack.getStackDepth() > 0) {
OpcodeStack.Item itm = stack.getStackItem(0);
if (itm.getReturnValueOf() != null) {
sawMethodWeight = 0;
conditionalTarget = -1;
}
}
break;
}
} finally {
stack.sawOpcode(this, seen);
if ((userValue != null) && (stack.getStackDepth() > 0)) {
OpcodeStack.Item itm = stack.getStackItem(0);
itm.setUserValue(userValue);
}
}
}
}
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