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/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2013 Eric Lafortune (eric@graphics.cornell.edu)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program 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 for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package proguard.optimize.info;
import proguard.classfile.*;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.instruction.*;
import proguard.classfile.instruction.visitor.InstructionVisitor;
import proguard.classfile.util.SimplifiedVisitor;
/**
* This InstructionVisitor marks all methods that branch backward in any of the
* instructions that it visits.
*
* @author Eric Lafortune
*/
public class BackwardBranchMarker
extends SimplifiedVisitor
implements InstructionVisitor
{
// Implementations for InstructionVisitor.
public void visitAnyInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, Instruction instruction) {}
public void visitBranchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, BranchInstruction branchInstruction)
{
markBackwardBranch(method, branchInstruction.branchOffset);
}
public void visitAnySwitchInstruction(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset, SwitchInstruction switchInstruction)
{
markBackwardBranch(method, switchInstruction.defaultOffset);
for (int index = 0; index < switchInstruction.jumpOffsets.length; index++)
{
markBackwardBranch(method, switchInstruction.jumpOffsets[index]);
}
}
// Small utility methods.
/**
* Marks the given method if the given branch offset is negative.
*/
private void markBackwardBranch(Method method, int branchOffset)
{
if (branchOffset < 0)
{
setBranchesBackward(method);
}
}
private static void setBranchesBackward(Method method)
{
MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
if (info != null)
{
info.setBranchesBackward();
}
}
public static boolean branchesBackward(Method method)
{
MethodOptimizationInfo info = MethodOptimizationInfo.getMethodOptimizationInfo(method);
return info == null || info.branchesBackward();
}
}
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