side effects

git-svn-id: https://svn.code.sf.net/p/jode/code/trunk@199 379699f6-c40d-0410-875b-85095c16579e

jode/jode/expr/ComplexExpression.java

@@ -24,6 +24,7 @@ import jode.Type;
 public class ComplexExpression extends Expression {
     Operator     operator;
     Expression[] subExpressions;
+    int operandcount = 0;
 
     public ComplexExpression(Operator op, Expression[] sub) {
         super(Type.tUnknown);
@@ -34,19 +35,15 @@ public class ComplexExpression extends Expression {
         operator = op;
         operator.parent = this;
         subExpressions = sub;
-        for (int i=0; i< subExpressions.length; i++)
+        for (int i=0; i< subExpressions.length; i++) {
             subExpressions[i].parent = this;
+	    operandcount += subExpressions[i].getOperandCount();
+	}
         updateType();
     }
 
     public int getOperandCount() {
-        if (subExpressions.length == 0)
-            return 0;
-        else
-            /* The only sub expression that may have non resolved
-             * operands may be the first.
-             */
-            return subExpressions[0].getOperandCount();
+	return operandcount;
     }
 
     public Expression negate() {
@@ -71,6 +68,22 @@ public class ComplexExpression extends Expression {
         return new ComplexExpression(negop, new Expression[] { this });
     }
 
+    /**
+     * Checks if the value of the given expression can change, due to
+     * side effects in this expression.  If this returns false, the 
+     * expression can safely be moved behind the current expresion.
+     * @param expr the expression that should not change.
+     */
+    public boolean hasSideEffects(Expression expr) {
+	if (operator.hasSideEffects(expr))
+	    return true;
+	for (int i=0; i < subExpressions.length; i++) {
+	    if (subExpressions[i].hasSideEffects(expr))
+		return true;
+	}
+	return false;
+    }
+
     /**
      * Checks if the given Expression (which must be a CombineableOperator)
      * can be combined into this expression.
@@ -103,7 +116,23 @@ public class ComplexExpression extends Expression {
     }
 
     /**
-     * Checks if this expression contains a load, that matches the
+     * Checks if this expression contains a conflicting load, that
+     * matches the given CombineableOperator.  The sub expressions are
+     * not checked.
+     * @param op The combineable operator.
+     * @return if this expression contains a matching load.  */
+    public boolean containsConflictingLoad(CombineableOperator op) {
+	if (op.matches(operator))
+	    return true;
+	for (int i=0; i < subExpressions.length; i++) {
+	    if (subExpressions[i].containsConflictingLoad(op))
+		return true;
+	}
+	return false;
+    }
+
+    /**
+     * Checks if this expression contains a conflicting load, that matches the
      * given Expression (which must be a
      * StoreInstruction/IIncOperator).
      * @param e The store expression.
@@ -169,9 +198,15 @@ public class ComplexExpression extends Expression {
     }
 
     public void setSubExpressions(int i, Expression expr) {
+	int diff = expr.getOperandCount()
+	    - subExpressions[i].getOperandCount();
         subExpressions[i] = expr;
+	for (ComplexExpression ce = this; ce != null; 
+	     ce = (ComplexExpression) ce.parent)
+	    ce.operandcount += diff;
         updateType();
     }
+
     void updateSubTypes() {
         boolean changed = false;
         for (int i=0; i < subExpressions.length; i++) {
@@ -456,5 +491,4 @@ public class ComplexExpression extends Expression {
                 return false;
         return true;
     }
-
 }

jode/jode/expr/ConstructorOperator.java

@@ -21,7 +21,8 @@ package jode.decompiler;
 import jode.Type;
 import jode.MethodType;
 
-public class ConstructorOperator extends Operator {
+public class ConstructorOperator extends Operator 
+    implements CombineableOperator {
     MethodType methodType;
     Type classType;
 
@@ -32,6 +33,32 @@ public class ConstructorOperator extends Operator {
         this.methodType = methodType;
     }
 
+    /**
+     * Checks if the value of the given expression can change, due to
+     * side effects in this expression.  If this returns false, the 
+     * expression can safely be moved behind the current expresion.
+     * @param expr the expression that should not change.
+     */
+    public boolean hasSideEffects(Expression expr) {
+	return expr.containsConflictingLoad(this);
+    }
+
+    /**
+     * Makes a non void expression out of this invoke instruction.
+     */
+    public void makeNonVoid() {
+	throw new jode.AssertError("already non void");
+    }
+
+    /**
+     * Checks if the value of the operator can be changed by this expression.
+     */
+    public boolean matches(Operator loadop) {
+        return (loadop instanceof InvokeOperator
+		|| loadop instanceof ConstructorOperator
+		|| loadop instanceof GetFieldOperator);
+    }
+
     public int getPriority() {
         return 950;
     }

jode/jode/expr/Expression.java

@@ -58,6 +58,17 @@ public abstract class Expression {
         return new ComplexExpression(negop, new Expression[] { this });
     }
 
+    /**
+     * Checks if the value of the given expression can change, due to
+     * side effects in this expression.  If this returns false, the 
+     * expression can safely be moved behind the current expresion.
+     * @param expr the expression that should not change.
+     */
+    public boolean hasSideEffects(Expression expr) {
+	// Most expression don't have side effects.
+	return false;
+    }
+
     /**
      * Checks if the given Expression (which should be a CombineableOperator)
      * can be combined into this expression.
@@ -82,6 +93,16 @@ public abstract class Expression {
         return ((CombineableOperator)e.getOperator()).matches(getOperator());
     }
 
+    /**
+     * Checks if this expression contains a conflicting load, that
+     * matches the given CombineableOperator.  The sub expressions are
+     * not checked.
+     * @param op The combineable operator.
+     * @return if this expression contains a matching load.  */
+    public boolean containsConflictingLoad(CombineableOperator op) {
+        return op.matches(getOperator());
+    }
+
     /**
      * Combines the given Expression (which should be a StoreInstruction)
      * into this expression.  You must only call this if
@@ -110,7 +131,8 @@ public abstract class Expression {
         return this;
     }
 
-    static Expression EMPTYSTRING = new ConstOperator(Type.tString, "\"\"");
+    public static Expression EMPTYSTRING
+	= new ConstOperator(Type.tString, "\"\"");
 
     public Expression simplifyStringBuffer() {
         return null;

jode/jode/expr/IIncOperator.java

@@ -59,6 +59,17 @@ implements LocalVarOperator, CombineableOperator {
         return 100;
     }
 
+
+    /**
+     * Checks if the value of the given expression can change, due to
+     * side effects in this expression.  If this returns false, the 
+     * expression can safely be moved behind the current expresion.
+     * @param expr the expression that should not change.
+     */
+    public boolean hasSideEffects(Expression expr) {
+	return expr.containsConflictingLoad(this);
+    }
+
     /**
      * Makes a non void expression out of this store instruction.
      */

jode/jode/expr/InvokeOperator.java

@@ -23,7 +23,8 @@ import jode.MethodType;
 import jode.Type;
 import jode.bytecode.ClassInfo;
 
-public final class InvokeOperator extends Operator {
+public final class InvokeOperator extends Operator 
+    implements CombineableOperator {
     CodeAnalyzer codeAnalyzer;
     boolean specialFlag;
     MethodType methodType;
@@ -44,6 +45,32 @@ public final class InvokeOperator extends Operator {
             classType.useType();
     }
 
+    /**
+     * Checks if the value of the given expression can change, due to
+     * side effects in this expression.  If this returns false, the 
+     * expression can safely be moved behind the current expresion.
+     * @param expr the expression that should not change.
+     */
+    public boolean hasSideEffects(Expression expr) {
+	return expr.containsConflictingLoad(this);
+    }
+
+    /**
+     * Makes a non void expression out of this invoke instruction.
+     */
+    public void makeNonVoid() {
+	throw new jode.AssertError("already non void");
+    }
+
+    /**
+     * Checks if the value of the operator can be changed by this expression.
+     */
+    public boolean matches(Operator loadop) {
+        return (loadop instanceof InvokeOperator
+		|| loadop instanceof ConstructorOperator
+		|| loadop instanceof GetFieldOperator);
+    }
+
     public boolean isStatic() {
         return methodType.isStatic();
     }
@@ -135,11 +162,7 @@ public final class InvokeOperator extends Operator {
         return method+"("+params+")";
     }
 
-    public boolean equals(Object o) {
-	return o instanceof InvokeOperator &&
-	    ((InvokeOperator)o).classType.equals(classType) &&
-	    ((InvokeOperator)o).methodName.equals(methodName) &&
-	    ((InvokeOperator)o).methodType.equals(methodType) &&
-	    ((InvokeOperator)o).specialFlag == specialFlag;
-    }
+    /* Invokes never equals: they may return different values even if
+     * they have the same parameters.
+     */
 }

jode/jode/expr/StoreInstruction.java

@@ -40,6 +40,16 @@ public abstract class StoreInstruction extends Operator
         return lvalueType;
     }
 
+    /**
+     * Checks if the value of the given expression can change, due to
+     * side effects in this expression.  If this returns false, the 
+     * expression can safely be moved behind the current expresion.
+     * @param expr the expression that should not change.
+     */
+    public boolean hasSideEffects(Expression expr) {
+	return expr.containsConflictingLoad(this);
+    }
+
     /**
      * Makes a non void expression out of this store instruction.
      */