/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Eclipse Public License (EPL);
* 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/eclipse-1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.compilers.opt.ir.operand;
/**
*
* @see Operand
*/
public final class BranchProfileOperand extends 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 BranchProfileOperand(float takenProbability) {
this.takenProbability = takenProbability;
}
public BranchProfileOperand() {
this.takenProbability = 0.5f;
}
public static BranchProfileOperand always() {
return new BranchProfileOperand(ALWAYS);
}
public static BranchProfileOperand likely() {
return new BranchProfileOperand(LIKELY);
}
public static BranchProfileOperand unlikely() {
return new BranchProfileOperand(UNLIKELY);
}
public static BranchProfileOperand never() {
return new BranchProfileOperand(NEVER);
}
/**
* Returns a copy of this branch operand.
*
* @return a copy of this operand
*/
@Override
public Operand copy() {
return new BranchProfileOperand(takenProbability);
}
/**
* Flip the probability (p = 1 - p)
*
* @return this
*/
public BranchProfileOperand flip() {
takenProbability = 1f - takenProbability;
return this;
}
@Override
public boolean similar(Operand op) {
return (op instanceof BranchProfileOperand) &&
(takenProbability == ((BranchProfileOperand) op).takenProbability);
}
/**
* Returns the string representation of this operand.
*
* @return a string representation of this operand.
*/
@Override
public String toString() {
return "Probability: " + takenProbability;
}
}