public JSSA(Type.Class c, DataInput in, ConstantPool cp) throws IOException {
super(c, in, cp);
+ local = new Expr[maxLocals];
+ stack = new Expr[maxStack];
for(int i=0; i<this.method.getNumArgs(); i++)
local[i] = new Argument("arg"+i, this.method.getArgType(i));
for(int i=0; i<size(); i++) {
// Instance Data; used ONLY during constructor; then thrown away /////////////////////////////////////////////////
/** this models the JVM locals; it is only used for unwinding stack-ops into an SSA-tree, then thrown away */
- private Expr[] local = new Expr[6];
+ private final Expr[] local;
/** this models the JVM stack; it is only used for unwinding stack-ops into an SSA-tree, then thrown away */
- private Expr[] stack = new Expr[65535];
+ private final Expr[] stack;
/** JVM stack pointer */
private int sp = 0;
- private Expr push(Expr e) { return stack[sp++] = e; }
- private Expr pop() { return stack[--sp]; }
+ private Expr push(Expr e) {
+ if(sp == stack.length-1) throw new IllegalStateException("stack overflow");
+ return stack[sp++] = e;
+ }
+ private Expr pop() {
+ if(sp == 0) throw new IllegalStateException("stack underflow");
+ return stack[--sp];
+ }
// SSA-node classes /////////////////////////////////////////////////////////////////////////////////////////
+ public final Expr VOID_EXPR = new Expr() {
+ public Type getType() { return Type.VOID; }
+ };
+
/** an purely imperative operation which does not generate data */
public abstract class Op {
//public abstract Op[] predecessors(); // not implemented yet
public class Cast extends Expr {
final Expr e;
final Type t;
- public Cast(Expr e, Type t) { this.e = e; this.t = t; }
+ public Cast(Expr e, Type t) {
+ if(e.getType().isRef() != t.isRef()) throw new IllegalArgumentException("invalid cast");
+ // FEATURE: Check that one is a subclass of the other if it is a ref
+ this.e = e;
+ this.t = t;
+ }
public Type getType() { return t; }
}
public class InstanceOf extends Expr {
final Expr e;
- final Type t;
- public InstanceOf(Expr e, Type t) { this.e = e; this.t = t; }
+ final Type.Ref t;
+ public InstanceOf(Expr e, Type.Ref t) {
+ if(!e.getType().isRef()) throw new IllegalArgumentException("can't do an instanceof check on a non-ref");
+ this.e = e;
+ this.t = t;
+ }
public Type getType() { return Type.BOOLEAN; }
}
public class Throw extends Op {
public final Expr e;
- public Throw(Expr e) { this.e = e; }
+ public Throw(Expr e) {
+ if(!e.getType().isRef()) throw new IllegalArgumentException("can't throw a non ref");
+ // FEATURE: CHeck that it is a subclass of Throwable
+ this.e = e;
+ }
}
public class Branch extends Op {
public class Return extends Op {
final Expr e;
- public Return() { this(null); }
+ public Return() { this(VOID_EXPR); }
public Return(Expr e) { this.e = e; }
- public String toString() { return e==null?"return":("return "+e.toString()); }
+ public String toString() { return e.getType() == Type.VOID ? "return" : ("return "+e.toString()); }
}
/** GETFIELD and GETSTATIC */
// Runtime Type information //////////////////////////////////////////////////////////////////////////////
- case CHECKCAST: push(new Cast(pop(), (Type)arg)); return null;
- case INSTANCEOF: push(new InstanceOf(pop(), (Type)arg)); return null;
+ case CHECKCAST: push(new Cast(pop(), (Type.Ref)arg)); return null;
+ case INSTANCEOF: push(new InstanceOf(pop(), (Type.Ref)arg)); return null;
case LDC: case LDC_W: case LDC2_W: push(new Constant(arg)); return null;