/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Common Public License (CPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/cpl1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.compilers.opt.ir;
/**
*
* @see OPT_Operand
*/
public final class OPT_BranchProfileOperand extends OPT_Operand {
public float takenProbability;
public static final float ALWAYS = 1f;
public static final float LIKELY = .99f;
public static final float UNLIKELY = 1f - LIKELY;
public static final float NEVER = 1f - ALWAYS;
public OPT_BranchProfileOperand(float takenProbability) {
this.takenProbability = takenProbability;
}
public OPT_BranchProfileOperand() {
this.takenProbability = 0.5f;
}
public static OPT_BranchProfileOperand always() {
return new OPT_BranchProfileOperand(ALWAYS);
}
public static OPT_BranchProfileOperand likely() {
return new OPT_BranchProfileOperand(LIKELY);
}
public static OPT_BranchProfileOperand unlikely() {
return new OPT_BranchProfileOperand(UNLIKELY);
}
public static OPT_BranchProfileOperand never() {
return new OPT_BranchProfileOperand(NEVER);
}
/**
* Returns a copy of this branch operand.
*
* @return a copy of this operand
*/
public OPT_Operand copy() {
return new OPT_BranchProfileOperand(takenProbability);
}
/**
* Flip the probability (p = 1 - p)
*/
public OPT_BranchProfileOperand flip() {
takenProbability = 1f - takenProbability;
return this;
}
/**
* Are two operands semantically equivalent?
*
* @param op other operand
* @return <code>true</code> if <code>this</code> and <code>op</code>
* are semantically equivalent or <code>false</code>
* if they are not.
*/
public boolean similar(OPT_Operand op) {
return (op instanceof OPT_BranchProfileOperand) &&
(takenProbability == ((OPT_BranchProfileOperand) op).takenProbability);
}
/**
* Returns the string representation of this operand.
*
* @return a string representation of this operand.
*/
public String toString() {
return "Probability: " + takenProbability;
}
}