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package soot.jimple.toolkits.scalar;
/*-
* #%L
* Soot - a J*va Optimization Framework
* %%
* Copyright (C) 1999 Phong Co
* %%
* This program 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 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 Lesser Public License for more details.
*
* You should have received a copy of the GNU General Lesser Public
* License along with this program. If not, see
* .
* #L%
*/
import soot.Value;
import soot.jimple.AddExpr;
import soot.jimple.AndExpr;
import soot.jimple.ArithmeticConstant;
import soot.jimple.BinopExpr;
import soot.jimple.ClassConstant;
import soot.jimple.CmpExpr;
import soot.jimple.CmpgExpr;
import soot.jimple.CmplExpr;
import soot.jimple.Constant;
import soot.jimple.DivExpr;
import soot.jimple.EqExpr;
import soot.jimple.GeExpr;
import soot.jimple.GtExpr;
import soot.jimple.IntConstant;
import soot.jimple.LeExpr;
import soot.jimple.LongConstant;
import soot.jimple.LtExpr;
import soot.jimple.MulExpr;
import soot.jimple.NeExpr;
import soot.jimple.NegExpr;
import soot.jimple.NullConstant;
import soot.jimple.NumericConstant;
import soot.jimple.OrExpr;
import soot.jimple.RealConstant;
import soot.jimple.RemExpr;
import soot.jimple.ShlExpr;
import soot.jimple.ShrExpr;
import soot.jimple.StringConstant;
import soot.jimple.SubExpr;
import soot.jimple.UnopExpr;
import soot.jimple.UshrExpr;
import soot.jimple.XorExpr;
public class Evaluator {
public static boolean isValueConstantValued(Value op) {
if (op instanceof Constant) {
return true;
} else if (op instanceof UnopExpr) {
Value innerOp = ((UnopExpr) op).getOp();
if (innerOp == NullConstant.v()) {
// operations on null will throw an exception and the operation
// is therefore not considered constant-valued; see posting on Soot list
// on 18 September 2007 14:36
return false;
}
if (isValueConstantValued(innerOp)) {
return true;
}
} else if (op instanceof BinopExpr) {
final BinopExpr binExpr = (BinopExpr) op;
final Value op1 = binExpr.getOp1();
final Value op2 = binExpr.getOp2();
// Only evaluate these checks once, and use the result multiple times
final boolean isOp1Constant = isValueConstantValued(op1);
final boolean isOp2Constant = isValueConstantValued(op2);
/* Handle weird cases. */
if (op instanceof DivExpr || op instanceof RemExpr) {
if (!isOp1Constant || !isOp2Constant) {
return false;
}
/* check for a 0 value. If so, punt. */
Value c2 = getConstantValueOf(op2);
if ((c2 instanceof IntConstant && ((IntConstant) c2).value == 0)
|| (c2 instanceof LongConstant && ((LongConstant) c2).value == 0)) {
return false;
}
}
if (isOp1Constant && isOp2Constant) {
return true;
}
}
return false;
} // isValueConstantValued
/**
* Returns the constant value of op if it is easy to find the constant value; else returns null.
*/
public static Value getConstantValueOf(Value op) {
if (!isValueConstantValued(op)) {
return null;
}
if (op instanceof Constant) {
return op;
} else if (op instanceof UnopExpr) {
Value c = getConstantValueOf(((UnopExpr) op).getOp());
if (op instanceof NegExpr) {
return ((NumericConstant) c).negate();
}
} else if (op instanceof BinopExpr) {
final BinopExpr binExpr = (BinopExpr) op;
final Value c1 = getConstantValueOf(binExpr.getOp1());
final Value c2 = getConstantValueOf(binExpr.getOp2());
if (op instanceof AddExpr) {
return ((NumericConstant) c1).add((NumericConstant) c2);
} else if (op instanceof SubExpr) {
return ((NumericConstant) c1).subtract((NumericConstant) c2);
} else if (op instanceof MulExpr) {
return ((NumericConstant) c1).multiply((NumericConstant) c2);
} else if (op instanceof DivExpr) {
return ((NumericConstant) c1).divide((NumericConstant) c2);
} else if (op instanceof RemExpr) {
return ((NumericConstant) c1).remainder((NumericConstant) c2);
} else if (op instanceof EqExpr || op instanceof NeExpr) {
if (c1 instanceof NumericConstant) {
if (!(c2 instanceof NumericConstant)) {
return IntConstant.v(0);
} else if (op instanceof EqExpr) {
return ((NumericConstant) c1).equalEqual((NumericConstant) c2);
} else if (op instanceof NeExpr) {
return ((NumericConstant) c1).notEqual((NumericConstant) c2);
}
} else if (c1 instanceof StringConstant || c1 instanceof NullConstant || c1 instanceof ClassConstant) {
boolean equality = c1.equals(c2);
boolean truth = (op instanceof EqExpr) ? equality : !equality;
return IntConstant.v(truth ? 1 : 0);
}
throw new RuntimeException("constant neither numeric nor string");
} else if (op instanceof GtExpr) {
return ((NumericConstant) c1).greaterThan((NumericConstant) c2);
} else if (op instanceof GeExpr) {
return ((NumericConstant) c1).greaterThanOrEqual((NumericConstant) c2);
} else if (op instanceof LtExpr) {
return ((NumericConstant) c1).lessThan((NumericConstant) c2);
} else if (op instanceof LeExpr) {
return ((NumericConstant) c1).lessThanOrEqual((NumericConstant) c2);
} else if (op instanceof AndExpr) {
return ((ArithmeticConstant) c1).and((ArithmeticConstant) c2);
} else if (op instanceof OrExpr) {
return ((ArithmeticConstant) c1).or((ArithmeticConstant) c2);
} else if (op instanceof XorExpr) {
return ((ArithmeticConstant) c1).xor((ArithmeticConstant) c2);
} else if (op instanceof ShlExpr) {
return ((ArithmeticConstant) c1).shiftLeft((ArithmeticConstant) c2);
} else if (op instanceof ShrExpr) {
return ((ArithmeticConstant) c1).shiftRight((ArithmeticConstant) c2);
} else if (op instanceof UshrExpr) {
return ((ArithmeticConstant) c1).unsignedShiftRight((ArithmeticConstant) c2);
} else if (op instanceof CmpExpr) {
if ((c1 instanceof LongConstant) && (c2 instanceof LongConstant)) {
return ((LongConstant) c1).cmp((LongConstant) c2);
} else {
throw new IllegalArgumentException("CmpExpr: LongConstant(s) expected");
}
} else if ((op instanceof CmpgExpr) || (op instanceof CmplExpr)) {
if ((c1 instanceof RealConstant) && (c2 instanceof RealConstant)) {
if (op instanceof CmpgExpr) {
return ((RealConstant) c1).cmpg((RealConstant) c2);
} else if (op instanceof CmplExpr) {
return ((RealConstant) c1).cmpl((RealConstant) c2);
}
} else {
throw new IllegalArgumentException("CmpExpr: RealConstant(s) expected");
}
} else {
throw new RuntimeException("unknown binop: " + op);
}
}
throw new RuntimeException("couldn't getConstantValueOf of: " + op);
} // getConstantValueOf
} // Evaluator