diff --git a/jode/jode/flow/VariableStack.java b/jode/jode/flow/VariableStack.java
new file mode 100644
index 0000000..bc63a27
--- /dev/null
+++ b/jode/jode/flow/VariableStack.java
@@ -0,0 +1,155 @@
+package jode.flow;
+import jode.decompiler.LocalInfo;
+import jode.expr.ComplexExpression;
+import jode.expr.Expression;
+import jode.expr.LocalLoadOperator;
+import jode.expr.Operator;
+
+/**
+ * This class represents the state of the stack at various points in
+ * the program.  Each entry is a anonymous local, which is used instead
+ * of the PUSH / stack_i statements. <p>
+ *
+ * This class is immutable, but note, that the local infos can get merged.
+ * @see FlowBlock.mapStackToLocal
+ * @see FlowBlock.removePush
+ */
+public class VariableStack {
+    public final static VariableStack EMPTY = 
+	new VariableStack(new LocalInfo[0]);
+
+    final LocalInfo[] stackMap; 
+
+    private VariableStack(LocalInfo[] stack) {
+	stackMap = stack;
+    }
+
+    public boolean isEmpty() {
+	return stackMap.length == 0;
+    }
+
+    public VariableStack pop(int count) {
+	LocalInfo[] newStack = new LocalInfo[stackMap.length - count];
+	System.arraycopy(stackMap, 0, newStack, 0, stackMap.length - count);
+	return new VariableStack(newStack);
+    }
+    
+    public VariableStack push(LocalInfo li) {
+	return poppush(0, li);
+    }
+    
+    public VariableStack poppush(int count, LocalInfo li) {
+	LocalInfo[] newStack = new LocalInfo[stackMap.length - count + 1];
+	System.arraycopy(stackMap, 0, newStack, 0, stackMap.length - count);
+	newStack[stackMap.length - count] = li;
+	return new VariableStack(newStack);
+    }
+    
+    public VariableStack peek(int count) {
+	LocalInfo[] peeked = new LocalInfo[count];
+	System.arraycopy(stackMap, stackMap.length - count, peeked, 0, count);
+	return new VariableStack(peeked);
+    }
+
+    public void merge(VariableStack other) {
+	if (stackMap.length != other.stackMap.length)
+	    throw new IllegalArgumentException("stack length differs");
+	for (int i=0; i<stackMap.length; i++) {
+	    if (stackMap[i].getType().stackSize()
+		!= other.stackMap[i].getType().stackSize())
+		throw new IllegalArgumentException
+		    ("stack element length differs at "+i);
+	    stackMap[i].combineWith(other.stackMap[i]);
+	}
+    }
+
+    /**
+     * Merge to VariableStacks.  Either one may be null, in which case
+     * the other is returned.
+     */
+    public static VariableStack merge(VariableStack first, 
+				      VariableStack second) {
+	if (first == null)
+	    return second;
+	else if (second == null)
+	    return first;
+	first.merge(second);
+	return first;
+    }
+
+    public Expression mergeIntoExpression(Expression expr, VariableSet used) {
+	/* assert expr.getOperandCount() == stackMap.length */
+
+	ComplexExpression parent = null;
+	Expression inner = expr;
+	while (inner instanceof ComplexExpression) {
+	    parent = (ComplexExpression)inner;
+	    inner = parent.getSubExpressions()[0];
+	}
+	Expression[] loads = new Expression[stackMap.length];
+	for (int i=0; i< stackMap.length; i++) {
+	    used.addElement(stackMap[i]);
+	    loads[i] = new LocalLoadOperator(stackMap[i].getType(),
+					     stackMap[i]);
+	}
+	Expression newExpr = new ComplexExpression((Operator)inner, loads);
+	if (parent != null)
+	    parent.setSubExpressions(0, newExpr);
+	else
+	    expr = newExpr;
+	return expr;
+    }
+
+    public VariableStack executeSpecial(SpecialBlock special) {
+	if (special.type == special.POP) {
+	    int popped = 0;
+	    int newLength = stackMap.length;
+	    while (popped < special.count) {
+		newLength--;
+		popped += stackMap[newLength].getType().stackSize();
+	    }
+	    if (popped != special.count)
+		throw new IllegalArgumentException("wrong POP");
+	    LocalInfo[] newStack = new LocalInfo[newLength];
+	    System.arraycopy(stackMap, 0, newStack, 0, newLength);
+	    return new VariableStack(newStack);
+	} else if (special.type == special.DUP) {
+	    int popped = 0;
+	    int numDup = 0;
+	    int startDup = stackMap.length;
+	    while (popped < special.count) {
+		startDup--;
+		numDup++;
+		popped += stackMap[startDup].getType().stackSize();
+	    }
+	    if (popped != special.count)
+		throw new IllegalArgumentException("wrong DUP");
+	    int destDup = startDup;
+	    int depth = 0;
+	    while (depth < special.depth) {
+		destDup--;
+		depth += stackMap[destDup].getType().stackSize();
+	    }
+	    if (depth != special.depth)
+		throw new IllegalArgumentException("wrong DUP");
+	    LocalInfo[] newStack = new LocalInfo[stackMap.length + numDup];
+	    System.arraycopy(stackMap, 0, newStack, 0, destDup);
+	    System.arraycopy(stackMap, startDup, newStack, destDup, numDup);
+	    System.arraycopy(stackMap, destDup, newStack, destDup + numDup,
+			     startDup - destDup);
+	    System.arraycopy(stackMap, startDup, newStack, startDup + numDup,
+			     numDup);
+	    return new VariableStack(newStack);
+	} else if (special.type == special.SWAP) {
+	    LocalInfo[] newStack = new LocalInfo[stackMap.length];
+	    System.arraycopy(stackMap, 0, newStack, 0, stackMap.length - 2);
+	    if (stackMap[stackMap.length-2].getType().stackSize() != 1
+		|| stackMap[stackMap.length-1].getType().stackSize() != 1)
+		throw new IllegalArgumentException("wrong SWAP");
+	    newStack[stackMap.length-2] = stackMap[stackMap.length-1];
+	    newStack[stackMap.length-1] = stackMap[stackMap.length-2];
+	    return new VariableStack(newStack);
+	} else
+	    throw new jode.AssertError("Unknown SpecialBlock");
+    }
+}
diff --git a/jode/test/ConstantTypes.java b/jode/test/ConstantTypes.java
new file mode 100644
index 0000000..fbd92f1
--- /dev/null
+++ b/jode/test/ConstantTypes.java
@@ -0,0 +1,53 @@
+package jode.test;
+
+public class ConstantTypes {
+    static boolean bool = true;
+    static byte    b  = (byte) 0x80;
+    static char    c  = '\u0080';
+    static short   s  = (short)'\u8234';
+    static int     i  = '\uffff';
+    
+    static void intFunc(int i){}
+    static void shortFunc(short s){}
+    static void charFunc(char c){}
+    static void byteFunc(byte b){}
+
+    static {
+	/* All casts are necessaray */
+	intFunc(25);
+	shortFunc((short) 25);
+	charFunc((char) 25);
+	byteFunc((byte) 25);
+	intFunc('\u0019');
+	shortFunc((short) '\u0019');
+	charFunc('\u0019');
+	byteFunc((byte) '\u0019');
+	intFunc(b);
+	intFunc(c);
+	intFunc(s);
+	intFunc(i);
+	shortFunc(b);
+	shortFunc((short)c);
+	shortFunc(s);
+	shortFunc((short)i);
+	charFunc((char)b);
+	charFunc(c);
+	charFunc((char)s);
+	charFunc((char)i);
+	byteFunc(b);
+	byteFunc((byte)c);
+	byteFunc((byte)s);
+	byteFunc((byte)i);
+	b = 42;
+	c = 42;
+	s = 42;
+	i = 42;
+	i = c;
+	s = b;
+	i = s;
+	c = (char) s;
+	s = (short) c;
+	c = (char) b;
+	b = (byte) c;
+    }
+}