X-Git-Url: http://git.megacz.com/?p=org.ibex.classgen.git;a=blobdiff_plain;f=src%2Forg%2Fibex%2Fclassgen%2FJSSA.java;h=2fc521ace03c227e2eec2ee45040f42d2af51988;hp=5161a4187c062e853831a6e63ca8122ad6a79e75;hb=7b7d64efd6761d48aabe652945e907e9309bccd0;hpb=0af18e327981bdae42ca0753ca05b4030bbdc848

diff --git a/src/org/ibex/classgen/JSSA.java b/src/org/ibex/classgen/JSSA.java
index 5161a41..2fc521a 100644
--- a/src/org/ibex/classgen/JSSA.java
+++ b/src/org/ibex/classgen/JSSA.java
@@ -13,58 +13,50 @@ public class JSSA extends MethodGen implements CGConst {
     
     public JSSA(Type.Class c, DataInput in, ConstantPool cp) throws IOException {
         super(c, in, cp);
-        local = new Expr[maxLocals];
-        stack = new Expr[maxStack];
-        int n=0;
-        if (!isStatic())
-            local[n++] = new Argument("this",method.getDeclaringClass());
-        for(int i=0;i<this.method.getNumArgs(); i++)
-            local[n++] = new Argument("arg"+i, this.method.getArgType(i));
+        sp = 0;
+        stacks = new Phi[size()][];
+        locals = new Phi[size()][];
         for(int i=0; i<size(); i++) {
-            int    op  = get(i);
-            Object arg = getArg(i);
+            int n = 0;
+            locals[i] = new Phi[maxLocals];
+            for(int j=0; j<locals[i].length; j++) locals[i][j] = new Phi();
+            if (i==0) {
+                if (!isStatic()) locals[i][n++].merge(new Argument("this",method.getDeclaringClass()));
+                for(int j=0;j<this.method.getNumArgs(); j++) locals[i][n++].merge(new Argument("arg"+j,this.method.getArgType(j)));
+            }
+        }
+
+        stack = new Phi[maxStack];
+        branchTo(0);
+        for(pc=0; pc<size(); pc++) {
+            int    op  = get(pc);
+            Object arg = getArg(pc);
             try {
                 Object o = addOp(op, arg);
                 if (o != null) {
                     ops[numOps] = o;
-                    ofs[numOps++] = i;
+                    ofs[numOps++] = pc;
                 }
+                if (o!=null && o instanceof Branch) ((Branch)o).branchTo();
+                if (o==null || (!(o instanceof Branch))) branchTo(pc+1);
             } catch(RuntimeException e) {
-                System.err.println("Had a problem at PC: " + i + " of " + method);
+                System.err.println("Had a problem at PC: " + pc + " of " + method);
                 e.printStackTrace();
                 throw new IOException("invalid class file");
             }
         }
     }
 
-    public void debugBodyToString(StringBuffer sb) {
-        StringBuffer sb0 = new StringBuffer();
-        super.debugBodyToString(sb0);
-        StringTokenizer st = new StringTokenizer(sb0.toString(), "\n");
-        String[] lines = new String[st.countTokens()];
-        for(int i=0; i<lines.length; i++) lines[i] = st.nextToken();
-        for(int j=0; j<ofs[0]; j++) {
-            String s = "    /* " + lines[j].trim();
-            while(s.length() < 50) s += " ";
-            s += " */";
-            sb.append(s);
-            sb.append("\n");
-        }
-        for(int i=0; i<numOps; i++) {
-            String s = "    /* " + lines[ofs[i]].trim();
-            while(s.length() < 50) s += " ";
-            s += " */  ";
-            s += ops[i].toString();
-            sb.append(s);
-            sb.append(";\n");
-            for(int j=ofs[i]+1; j<(i==numOps-1?size():ofs[i+1]); j++) {
-                s = "    /* " + lines[j].trim();
-                while(s.length() < 50) s += " ";
-                s += " */";
-                sb.append(s);
-                sb.append("\n");
-            }
+    public void branchTo(int newPC) {
+        System.out.println("!!!branchTo("+newPC+")!!!");
+        if (stacks[newPC] == null) {
+            stacks[newPC] = new Phi[sp];
+            for(int i=0; i<sp; i++) stacks[newPC][i] = new Phi();
         }
+        if (stacks[newPC].length != sp)
+            throw new IllegalArgumentException("stack depth disagreement: " + sp + " " + stacks[newPC].length);
+        for(int i=0; i<stacks[newPC].length; i++) stacks[newPC][i].merge(stack[i]);
+        for(int i=0; i<maxLocals; i++) locals[newPC][i].merge(locals[pc][i]);
     }
     
     private Object[] ops = new Object[65535];
@@ -74,25 +66,31 @@ public class JSSA extends MethodGen implements CGConst {
     // 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 final Expr[] local;
+    private final Phi[][] locals;
     
     /** this models the JVM stack; it is only used for unwinding stack-ops into an SSA-tree, then thrown away */
-    private final Expr[] stack;
+    private final Phi[][] stacks;
+    private final Phi[] stack;
 
     /** JVM stack pointer */
+    private int pc = 0;
     private int sp = 0;
-    
-    private Expr push(Expr e) {
-        if(sp == stack.length) {
-            for(int i=0;i<stack.length;i++) System.err.println("Stack " + i + ": " + stack[i]);
-            throw new IllegalStateException("stack overflow (" + stack.length + ")");
-        }
-        if(e.getType() == Type.VOID) throw new IllegalArgumentException("can't push a void");
-        return stack[sp++] = e;
+
+    private void push(Expr e) {
+        if (e.getType() == Type.VOID) throw new IllegalArgumentException("can't push a void");
+        if (stack[sp] == null) stack[sp] = new Phi();
+        stack[sp++].merge(e);
     }
     private Expr pop() {
-        if(sp == 0) throw new IllegalStateException("stack underflow");
-        return stack[--sp];
+        Expr ret = stack[sp-1];
+        stack[sp-1] = null;
+        sp--;
+        return ret;
+    }
+    
+    private Op seqPush(Expr e) {
+        push(e);
+        return new Seq(e);
     }
 
 
@@ -114,7 +112,16 @@ public class JSSA extends MethodGen implements CGConst {
             return name;
         }
     }
-
+    
+    /** A sequence point. expr is evaluated for side effects at this point, this does not generate data 
+        Expressions that haven't been evaluated with Seq are evaluated when they are first encountered
+      */
+    public class Seq extends Op {
+        private final Expr expr;
+        public String toString() { return expr.toString(); }
+        public Seq(Expr expr) { this.expr = expr; }
+    }
+    
     /** an operation which generates data */
     public abstract class Expr extends Op {
         //public abstract Expr[] contributors();  // not implemented yet
@@ -123,59 +130,120 @@ public class JSSA extends MethodGen implements CGConst {
         /** every JSSA.Expr either remembers its type _OR_ knows how to figure it out (the latter is preferred to eliminate
          *  redundant information that could possibly "disagree" with itself -- this happened a LOT in Soot) */
         public abstract Type getType();
+        public String _toString() { return super.toString(); }
+        public String toString() { return _toString(); } /*
+            String s = (String)bindingMap.get(this);
+            if (s != null) return s;
+            String prefix;
+            if (getType() == Type.VOID) return _toString();
+            else if (getType() == Type.DOUBLE || getType() == Type.FLOAT) prefix = "f";
+            else if (getType().isPrimitive()) prefix = "i";
+            else if (getType().isArray()) prefix = "a";
+            else prefix = "o";
+            s = prefix + (nextVar++);
+            bindingMap.put(this,s);
+            return "(" + s + " = " + _toString() + ")";
+            }*/
     }
 
     /**
-     *  A "nondeterministic merge" -- for example when the first instruction in a loop reads from a local which could have been
-     *  written to either by some instruction at the end of the previous iteration of the loop or by some instruction before
+     *  A "nondeterministic merge" -- for example when the first
+     *  instruction in a loop reads from a local which could have been
+     *  written to either by some instruction at the end of the
+     *  previous iteration of the loop or by some instruction before
      *  the loop (on the first iteration).
+     *
+     *  Note that Phi's are *mutable*.  This means that when one Phi
+     *  holds a reference to another, updates to the referenced Phi
+     *  are "seen" by the other Phi.  This prevents us from having to
+     *  repeat loops to propagate the Phis.
      */
     public class Phi extends Expr {
-        private final Expr[] inputs;
-        public Phi(Expr[] inputs) {
-            this.inputs = new Expr[inputs.length];
-            System.arraycopy(inputs, 0, this.inputs, 0, inputs.length);
+        Expr[] inputs;
+        public Phi(Expr[] inputs) { this.inputs = inputs; }
+        public Phi() { this.inputs = new Expr[0]; }
+        public Phi(Expr e1) {
+            this.inputs = new Expr[1];
+            inputs[0] = e1;
+        }
+        public Phi(Expr e1, Expr e2) {
+            this.inputs = new Expr[2];
+            inputs[0] = e1;
+            inputs[1] = e2;
+        }
+        public void merge(Expr e) {
+            if (e==this) return;
+            for(int i=0; i<inputs.length; i++) if (inputs[i]==e) return;
+            Expr[] newinputs = new Expr[inputs.length + 1];
+            System.arraycopy(inputs, 0, newinputs, 0, inputs.length);
+            newinputs[newinputs.length-1] = e;
+            inputs = newinputs;
+        }
+        public String toString() {
+            if (inputs.length == 1) return inputs[0].toString();
+            StringBuffer ret = new StringBuffer();
+            int count = 0;
+            for(int i=0; i<inputs.length; i++) {
+                String s = inputs[i].toString().trim();
+                if (s.length() == 0) continue;
+                count++;
+                ret.append(s);
+                ret.append(" ");
+            }
+            if (count == 0) return "";
+            if (count == 1) return ret.toString().trim();
+            return "{{ " + ret.toString() + "}}";
+            //return "{"+ret+"}";
         }
         public Type getType() {
+            if (inputs.length == 0) return null;
             // sanity check
             Type t = inputs[0].getType();
 
             // FIXME: actually this should check type-unifiability... fe, the "type of null" unifies with any Type.Ref
-            for(int i=1; i<inputs.length; i++)
+            for(int i=1; i<inputs.length; i++) {
+                if (t==null) { t = inputs[i].getType(); continue; }
+                if (inputs[i].getType() == null) continue;
                 if (inputs[i].getType() != t)
-                    throw new Error("Phi node with disagreeing types!  Crisis!");
+                    throw new Error("Phi node with disagreeing types: " + t + " " + inputs[i].getType() +"\n  Crisis!");
+            }
             return t;
         }
     }
 
+    public Phi phi(Expr e) { return e instanceof Phi ? ((Phi)e) : new Phi(e); }
+
     public class Argument extends Expr {
         public final String name;
         public final Type t;
         public Argument(String name, Type t) { this.name = name; this.t = t; }
-        public String toString() { return name; }
+        public String _toString() { return name; }
         public Type getType() { return t; }
     }
     
-    // Unary Operations
+
+    // Unary Operations //////////////////////////////////////////////////////////////////////////////
+    
     public class Not extends Expr {
         public final Expr e;
         public Not(Expr e) {
-            if(e.getType() != Type.BOOLEAN) throw new IllegalArgumentException("not needs a boolean expression");
+            if (e.getType() != Type.BOOLEAN) throw new IllegalArgumentException("not needs a boolean expression");
             this.e = e;
         }
         public Type getType() { return Type.BOOLEAN; }
-        public String toString() { return "!(" + e + ")"; }
+        public String _toString() { return "!(" + e + ")"; }
     }
     
     public class Neg extends Expr {
         public final Expr e;
         public Neg(Expr e) {
-            if(!e.getType().isPrimitive()) throw new IllegalArgumentException("can only negate a primitive");
+            if (!e.getType().isPrimitive()) throw new IllegalArgumentException("can only negate a primitive");
             this.e = e;
         }
         public Type getType() { return e.getType(); }
-        public String toString() { return "- (" + e + ")"; }
+        public String _toString() { return "- (" + e + ")"; }
     }
+
     
     // Binary Operations //////////////////////////////////////////////////////////////////////////////
 
@@ -184,8 +252,8 @@ public class JSSA extends MethodGen implements CGConst {
         public final Expr e2;
         private final String show;
         public BinExpr(Expr e1, Expr e2, String show) { this.e1 = e1; this.e2 = e2; this.show = show; }
-        public String toString() {
-            // FEATURE: should we be doing some precedence stuff here? probably no worth it for debugging output
+        public String _toString() {
+            // FEATURE: should we be doing some precedence stuff here? probably not worth it for debugging output
             return "(" + e1 + show + e2 + ")";
         }
     }
@@ -198,10 +266,10 @@ public class JSSA extends MethodGen implements CGConst {
     public class Eq extends Comparison {
         public Eq(Expr e1, Expr e2) {
             super(e1, e2, "=="); 
-            if(e1.getType().isPrimitive() != e2.getType().isPrimitive())
-                throw new IllegalArgumentException("type mismatch");
-            if(e1.getType().isPrimitive() && e1.getType() != e2.getType())
-                throw new IllegalArgumentException("type mismatch");            
+            if (e1.getType().isPrimitive() != e2.getType().isPrimitive())
+                throw new IllegalArgumentException("type mismatch: " + e1.getType() + " and " + e2.getType());
+            if (e1.getType().isPrimitive() && e1.getType() != e2.getType())
+                throw new IllegalArgumentException("type mismatch: " + e1.getType() + " and " + e2.getType());
             // FEATURE: Check if we can compare these classes
         }
     }
@@ -210,7 +278,7 @@ public class JSSA extends MethodGen implements CGConst {
     public class PrimitiveComparison extends Comparison {
         public PrimitiveComparison(Expr e1, Expr e2, String show) {
             super(e1, e2, show);
-            if(!e1.getType().isPrimitive() || e1.getType() != e2.getType()) throw new IllegalArgumentException("type mismatch");
+            if (!e1.getType().isPrimitive() || e1.getType() != e2.getType()) throw new IllegalArgumentException("type mismatch");
         }
     }
     
@@ -218,13 +286,16 @@ public class JSSA extends MethodGen implements CGConst {
     public class Lt extends PrimitiveComparison { public Lt(Expr e1, Expr e2) { super(e1, e2, "<"); } }
     public class Ge extends PrimitiveComparison { public Ge(Expr e1, Expr e2) { super(e1, e2, ">="); } }
     public class Le extends PrimitiveComparison { public Le(Expr e1, Expr e2) { super(e1, e2, "<="); } }
+
     
+
     // Math Operations //////////////////////////////////////////////////////////////////////////////
 
     public class BinMath extends BinExpr {
         public BinMath(Expr e1, Expr e2, String show) {
             super(e2, e1, show); 
-            if(e1.getType() != e2.getType()) throw new IllegalArgumentException("types disagree");
+            if (e1.getType() != null && e2.getType() != null && e1.getType() != e2.getType())
+                throw new IllegalArgumentException("types disagree");
         }
         public Type getType() { return e1.getType(); }
     }
@@ -242,8 +313,8 @@ public class JSSA extends MethodGen implements CGConst {
         public BitShiftExpr(Expr e1, Expr e2, String show) {
             super(e1,e2,show);
             Type t = e1.getType();
-            if(t != Type.INT && t != Type.LONG) throw new IllegalArgumentException("type mismatch");
-            if(e2.getType() != Type.INT) throw new IllegalArgumentException("type mismatch");
+            if (t != Type.INT && t != Type.LONG) throw new IllegalArgumentException("type mismatch");
+            if (e2.getType() != Type.INT) throw new IllegalArgumentException("type mismatch");
         }
         public Type getType() { return e1.getType(); }
     }
@@ -251,13 +322,14 @@ public class JSSA extends MethodGen implements CGConst {
     public class Shr  extends BitShiftExpr { public  Shr(Expr e, Expr e2) { super(e, e2, ">>"); } }
     public class Ushr extends BitShiftExpr { public Ushr(Expr e, Expr e2) { super(e, e2, ">>>"); } }
 
+
     // Other operations //////////////////////////////////////////////////////////////////////////////
 
     public class Cast extends Expr {
         final Expr e;
         final Type t;
         public Cast(Expr e, Type t) {
-            if(e.getType().isRef() != t.isRef()) throw new IllegalArgumentException("invalid cast");
+            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; 
@@ -269,46 +341,83 @@ public class JSSA extends MethodGen implements CGConst {
         final Expr e;
         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");
+            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 class Branch extends Op {
+        Expr destination = null;
+        public Branch(Expr destination) { this.destination = destination; }
+        public Branch(MethodGen.Switch s) { /* FIXME */ }
+        public Branch() { }
+        public void branchTo() { if (destination != null) branchTo(destination); }
+        private void branchTo(Expr e) {
+            if (e instanceof Phi) {
+                Phi phi = (Phi)e;
+                for(int i=0; i<phi.inputs.length; i++) branchTo(phi.inputs[i]);
+            } else if (e instanceof Label) {
+                JSSA.this.branchTo(((Label)e).pc);
+            } else {
+                throw new IllegalArgumentException("can't branch to a " + e.getClass());
+            }
+        }
+    }
+    public class Throw extends Branch {
         public final Expr e;
         public Throw(Expr e) {
-            if(!e.getType().isRef()) throw new IllegalArgumentException("can't throw a non ref");
+            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 Branch(Expr condition, Object destination) { }
-        public Branch(Label destination) { }
-        public Branch(MethodGen.Switch s) { }
-        public Branch() { }
+    public class Return extends Branch {
+        final Expr e;
+        public Return() { this(VOID_EXPR); }
+        public Return(Expr e) {
+            this.e = e; 
+            if (Type.unify(method.getReturnType(),e.getType()) != method.getReturnType())
+               throw new IllegalArgumentException("type mismatch");
+        }
+        public String toString() { return e.getType() == Type.VOID ? "return" : ("return "+e.toString()); }
+    }
+    public class Goto extends Branch {
+        public Goto(Expr destination) { super(destination); }
+        public String toString() { return "goto " + destination; }
+    }
+    public class RET extends Branch {
+        public RET(Expr destination) { super(destination); }
+        public String toString() { return "retsub [" + destination + "]"; }
+    }
+    public class JSR extends Branch {
+        public JSR(Expr destination) { super(destination); }
+        public String toString() { return "callsub " + destination; }
+    }
+    public class If extends Branch {
+        Expr condition = null;
+        public If(Expr condition, Expr destination) { super(destination); this.condition = condition; }
+        public String toString() { return "if (" + condition + ") goto " + destination; }
+        public void branchTo() {
+            if (condition != null) JSSA.this.branchTo(pc+1);
+            super.branchTo();
+        }
     }
-    public class Goto extends Branch { }
-    public class RET extends Branch { }
-    public class JSR extends Branch { public JSR(Label l) { super(l); } }
-    public class If extends Branch { }
 
     /** represents a "returnaddr" pushed onto the stack */
     public class Label extends Expr {
-        public final Op op;
+        public int pc;
+        public Label(int i) { this.pc = i; }
         public Type getType() { throw new Error("attempted to call getType() on a Label"); }
-        public Label(Op op) { this.op = op; }
-        public Label(int i) { this.op = null; /* FIXME */ }
+        public String toString() { return "<<label " + pc + ">>"; }
     }
 
     public class New extends Expr {
         public final Type.Class t;
         public Type getType() { return t; }
         public New(Type.Class t) { this.t = t; }
-        public String toString() { return "new " + t + "(...)"; }
+        public String _toString() { return "new " + t + "()"; }
     }
     
     public class NewArray extends Expr {
@@ -317,15 +426,20 @@ public class JSSA extends MethodGen implements CGConst {
         public NewArray(Type.Array t, Expr[] dims) { this.t = t; this.dims = dims; }
         public NewArray(Type.Array t, Expr dim) { this(t,new Expr[]{dim}); }
         public Type getType() { return t; }
+        public String _toString() {
+            Type base = t;
+            int totalDims = 0;
+            while(base.isArray()) {
+                totalDims++;
+                base = base.asArray().getElementType(); 
+            }
+            StringBuffer sb = new StringBuffer("new " + base);
+            for(int i=0;i<totalDims;i++)
+                sb.append("[" + (i < dims.length ? dims[i].toString() : "") + "]");
+            return sb.toString();
+        }
     }
     
-    public class Return extends Op {
-        final Expr e;
-        public Return() { this(VOID_EXPR); }
-        public Return(Expr e) { this.e = e; }
-        public String toString() { return e.getType() == Type.VOID ? "return" : ("return "+e.toString()); }
-    }
-
     /** GETFIELD and GETSTATIC */
     public class Get extends Expr {
         final Type.Class.Field f;
@@ -333,7 +447,7 @@ public class JSSA extends MethodGen implements CGConst {
         public Type getType() { return f.getType(); }
         public Get(Type.Class.Field f) { this(f, null); }
         public Get(Type.Class.Field f, Expr e) { this.f = f; this.e = e; }
-        public String toString() {
+        public String _toString() {
             return
                 (e!=null
                  ? e+"."+f.name
@@ -362,13 +476,15 @@ public class JSSA extends MethodGen implements CGConst {
 
     public class ArrayPut extends Op {
         final Expr e, i, v;
-        public ArrayPut(Expr e, Expr i, Expr v) { this.e = e; this.i = i; this.v = v; }
+        public ArrayPut(Expr v, Expr i, Expr e) { this.e = e; this.i = i; this.v = v; }
+        public String toString() { return e + "[" + i + "] := " + v; }
     }
 
     public class ArrayGet extends Expr {
         final Expr e, i;
-        public ArrayGet(Expr e, Expr i) { this.e = e; this.i = i; }
+        public ArrayGet(Expr i, Expr e) { this.e = e; this.i = i; }
         public Type getType() { return e.getType().asArray().getElementType(); }
+        public String _toString() { return e + "[" + i + "]"; }
     }
 
     public class ArrayLength extends Expr {
@@ -392,7 +508,7 @@ public class JSSA extends MethodGen implements CGConst {
             sb.append(")");
         }
 
-        public String toString() {
+        public String _toString() {
             StringBuffer sb = new StringBuffer();
             sb.append(method.getDeclaringClass() == JSSA.this.method.getDeclaringClass()
                       ? method.name
@@ -404,14 +520,17 @@ public class JSSA extends MethodGen implements CGConst {
     public class InvokeStatic    extends Invoke  { public InvokeStatic(Type.Class.Method m, Expr[] a) { super(m,a); } }
     public class InvokeSpecial   extends InvokeVirtual {
         public InvokeSpecial(Type.Class.Method m, Expr[] a, Expr e) { super(m,a,e); }
-        public String toString() { return toString(method.name.equals("<init>") ? method.getDeclaringClass().getName() : method.name); }
+        public String _toString() { return _toString(method.name.equals("<init>")
+                                                     ? method.getDeclaringClass().getName()
+                                                     : method.name); }
     }
-    public class InvokeInterface extends InvokeVirtual{public InvokeInterface(Type.Class.Method m, Expr[] a, Expr e){super(m,a,e);}}
+    public class InvokeInterface extends InvokeVirtual{
+        public InvokeInterface(Type.Class.Method m, Expr[] a, Expr e) { super(m,a,e); } }
     public class InvokeVirtual   extends Invoke  {
         public final Expr instance;
         public InvokeVirtual(Type.Class.Method m, Expr[] a, Expr e) { super(m, a); instance = e; }
-        public String toString() { return toString(method.name); }
-        protected String toString(String name) {
+        public String _toString() { return _toString(method.name); }
+        protected String _toString(String name) {
             StringBuffer sb = new StringBuffer();
             sb.append(instance+".");
             sb.append(name);
@@ -424,8 +543,9 @@ public class JSSA extends MethodGen implements CGConst {
         private final Object o;
         public Constant(int i) { this(new Integer(i)); }
         public Constant(Object o) { this.o = o; }
-        public String toString() { return o instanceof String ? "\"" + o + "\"" : o.toString(); }
+        public String toString() { return o == null ? "null" : o instanceof String ? "\"" + o + "\"" : o.toString(); }
         public Type getType() {
+            if (o == null) return Type.NULL;
             if (o instanceof Byte) return Type.BYTE;
             if (o instanceof Short) return Type.SHORT;
             if (o instanceof Character) return Type.CHAR;
@@ -458,34 +578,41 @@ public class JSSA extends MethodGen implements CGConst {
             i1 = p.i1;
             i2 = p.i2;
         }
+        if (arg instanceof Number) i1 = ((Integer)arg).intValue();
+        Label label = (arg instanceof Label) ? (Label)arg : null;
         switch(op) {
 
             case NOP: return null;
 
                 // Stack manipulations //////////////////////////////////////////////////////////////////////////////
 
-            case ACONST_NULL:                                                      return stack[sp++] = new Constant(null);
-            case ICONST_M1:                                                        return stack[sp++] = new Constant(-1);
-            case ICONST_0: case LCONST_0: case FCONST_0: case DCONST_0:            push(new Constant(0)); return null;
-            case ICONST_1: case LCONST_1: case FCONST_1: case DCONST_1:            push(new Constant(1)); return null;
-            case ICONST_2: case FCONST_2:                                          push(new Constant(2)); return null;
-            case ICONST_3:                                                         push(new Constant(3)); return null;
-            case ICONST_4:                                                         push(new Constant(4)); return null;
-            case ICONST_5:                                                         push(new Constant(5)); return null;
-            case ILOAD:    case LLOAD:    case FLOAD:    case DLOAD:    case ALOAD:    return push(local[i1]);
-            case ILOAD_0:  case LLOAD_0:  case FLOAD_0:  case DLOAD_0:  case ALOAD_0:  return push(local[0]);
-            case ILOAD_1:  case LLOAD_1:  case FLOAD_1:  case DLOAD_1:  case ALOAD_1:  return push(local[1]);
-            case ALOAD_2:  case DLOAD_2:  case FLOAD_2:  case LLOAD_2:  case ILOAD_2:  return push(local[2]);
-            case ILOAD_3:  case LLOAD_3:  case FLOAD_3:  case DLOAD_3:  case ALOAD_3:  return push(local[3]);
-            case ISTORE:   case LSTORE:   case FSTORE:   case DSTORE:   case ASTORE:   local[i1] = pop(); return null;
-            case ISTORE_0: case LSTORE_0: case FSTORE_0: case DSTORE_0: case ASTORE_0: local[0]  = pop(); return null;
-            case ISTORE_1: case LSTORE_1: case FSTORE_1: case DSTORE_1: case ASTORE_1: local[1]  = pop(); return null;
-            case ASTORE_2: case DSTORE_2: case FSTORE_2: case LSTORE_2: case ISTORE_2: local[2]  = pop(); return null;
-            case ISTORE_3: case LSTORE_3: case FSTORE_3: case DSTORE_3: case ASTORE_3: local[3]  = pop(); return null;
-            case POP:      pop(); return null;
-            case POP2:     pop(); pop(); return null;
-            case DUP:      push(stack[sp-1]); return null;
-            case DUP2:     push(stack[sp-2]); push(stack[sp-2]); return null;
+            case ACONST_NULL:                                                          push(new Constant(null)); return null;
+            case ICONST_M1:                                                            push(new Constant(-1));   return null;
+            case ICONST_0: case LCONST_0: case FCONST_0: case DCONST_0:                push(new Constant(0));    return null;
+            case ICONST_1: case LCONST_1: case FCONST_1: case DCONST_1:                push(new Constant(1));    return null;
+            case ICONST_2: case FCONST_2:                                              push(new Constant(2));    return null;
+            case ICONST_3:                                                             push(new Constant(3));    return null;
+            case ICONST_4:                                                             push(new Constant(4));    return null;
+            case ICONST_5:                                                             push(new Constant(5));    return null;
+            case ILOAD:    case LLOAD:    case FLOAD:    case DLOAD:    case ALOAD:    push(locals[pc][i1]);     return null;
+            case ILOAD_0:  case LLOAD_0:  case FLOAD_0:  case DLOAD_0:  case ALOAD_0:  push(locals[pc][0]);      return null;
+            case ILOAD_1:  case LLOAD_1:  case FLOAD_1:  case DLOAD_1:  case ALOAD_1:  push(locals[pc][1]);      return null;
+            case ALOAD_2:  case DLOAD_2:  case FLOAD_2:  case LLOAD_2:  case ILOAD_2:  push(locals[pc][2]);      return null;
+            case ILOAD_3:  case LLOAD_3:  case FLOAD_3:  case DLOAD_3:  case ALOAD_3:  push(locals[pc][3]);      return null;
+            case ISTORE:   case LSTORE:   case FSTORE:   case DSTORE:   case ASTORE:
+                locals[pc+1][i1].merge(pop()); return null;
+            case ISTORE_0: case LSTORE_0: case FSTORE_0: case DSTORE_0: case ASTORE_0:
+                locals[pc+1][0].merge(pop()); return null;
+            case ISTORE_1: case LSTORE_1: case FSTORE_1: case DSTORE_1: case ASTORE_1:
+                locals[pc+1][1].merge(pop()); return null;
+            case ASTORE_2: case DSTORE_2: case FSTORE_2: case LSTORE_2: case ISTORE_2:
+                locals[pc+1][2].merge(pop()); return null;
+            case ISTORE_3: case LSTORE_3: case FSTORE_3: case DSTORE_3: case ASTORE_3:
+                locals[pc+1][3].merge(pop()); return null;
+            case POP:                                                                  pop();                    return null;
+            case POP2:                                                                 pop(); pop();             return null;
+            case DUP:   push(stack[sp-1]);                  return null;
+            case DUP2:  push(stack[sp-2]); push(stack[sp-1]); return null;
 
                 // Conversions //////////////////////////////////////////////////////////////////////////////
 
@@ -503,52 +630,54 @@ public class JSSA extends MethodGen implements CGConst {
 
                 // Math //////////////////////////////////////////////////////////////////////////////
                    
-            case IADD: case LADD: case FADD: case DADD: push(new Add(pop(), pop())); return null;
-            case ISUB: case LSUB: case FSUB: case DSUB: push(new Sub(pop(), pop())); return null;
-            case IMUL: case LMUL: case FMUL: case DMUL: push(new Mul(pop(), pop())); return null;
-            case IREM: case LREM: case FREM: case DREM: push(new Rem(pop(), pop())); return null;
-                //case INEG: case LNEG: case FNEG: case DNEG: push(new Neg(pop())); return null;
-            case IDIV: case LDIV: case FDIV: case DDIV: push(new Div(pop(), pop())); return null;
-            case ISHL: case LSHL:                       push(new Shl(pop(), pop())); return null;
-            case ISHR: case LSHR:                       push(new Shr(pop(), pop())); return null;
+            case IADD: case LADD: case FADD: case DADD: push(new Add(pop(), pop()));  return null;
+            case ISUB: case LSUB: case FSUB: case DSUB: push(new Sub(pop(), pop()));  return null;
+            case IMUL: case LMUL: case FMUL: case DMUL: push(new Mul(pop(), pop()));  return null;
+            case IREM: case LREM: case FREM: case DREM: push(new Rem(pop(), pop()));  return null;
+            case INEG: case LNEG: case FNEG: case DNEG: push(new Neg(pop()));         return null;
+            case IDIV: case LDIV: case FDIV: case DDIV: push(new Div(pop(), pop()));  return null;
+            case ISHL: case LSHL:                       push(new Shl(pop(), pop()));  return null;
+            case ISHR: case LSHR:                       push(new Shr(pop(), pop()));  return null;
             case IUSHR: case LUSHR:                     push(new Ushr(pop(), pop())); return null;
-            case IAND: case LAND:                       push(new And(pop(), pop())); return null;
-            case IOR:  case LOR:                        push(new Or(pop(), pop())); return null;
-            case IXOR: case LXOR:                       push(new Xor(pop(), pop())); return null;
-            case IINC:                                  return local[i1] = new Add(local[i1], new Constant(i2));
+            case IAND: case LAND:                       push(new And(pop(), pop()));  return null;
+            case IOR:  case LOR:                        push(new Or(pop(), pop()));   return null;
+            case IXOR: case LXOR:                       push(new Xor(pop(), pop()));  return null;
+            case IINC:                                  return locals[pc+1][i1] = phi(new Add(locals[pc][i1], new Constant(i2)));
 
                 // Control and branching //////////////////////////////////////////////////////////////////////////////
 
-            case IFNULL:                                return new Branch(new Eq(pop(), new Constant(null)), new Label(i1));
-            case IFNONNULL:                             return new Branch(new Not(new Eq(pop(),new Constant(null))),new Label(i1));
-            case IFEQ:                                  return new Branch(    new Eq(new Constant(0), pop()),  arg);
-            case IFNE:                                  return new Branch(new Not(new Eq(new Constant(0), pop())), arg);
-            case IFLT:                                  return new Branch(    new Lt(new Constant(0), pop()),  arg);
-            case IFGE:                                  return new Branch(new Not(new Lt(new Constant(0), pop())), arg);
-            case IFGT:                                  return new Branch(    new Gt(new Constant(0), pop()),  arg);
-            case IFLE:                                  return new Branch(new Not(new Gt(new Constant(0), pop())), arg);
-            case IF_ICMPEQ:                             return new Branch(    new Eq(pop(), pop()),  arg);
-            case IF_ICMPNE:                             return new Branch(new Not(new Eq(pop(), pop())), arg);
-            case IF_ICMPLT:                             return new Branch(    new Lt(pop(), pop()),  arg);
-            case IF_ICMPGE:                             return new Branch(new Not(new Lt(pop(), pop())), arg);
-            case IF_ICMPGT:                             return new Branch(    new Gt(pop(), pop()),  arg);
-            case IF_ICMPLE:                             return new Branch(new Not(new Gt(pop(), pop())), arg);
-            case IF_ACMPEQ:                             return new Branch(    new Eq(pop(), pop()),  arg);
-            case IF_ACMPNE:                             return new Branch(new Not(new Eq(pop(), pop())), arg);
-            case ATHROW:                                return new Throw(pop());
-            case GOTO:                                  return new Branch(new Label(i1));
-            case JSR:                                   return new JSR(new Label(i1));
-            case RET:                                   return new RET();
-            case RETURN:                                return new Return();
+            case IFNULL:                                return new If(new Eq(pop(), new Constant(null)), new Label(i1));
+            case IFNONNULL:                             return new If(new Not(new Eq(pop(),new Constant(null))),new Label(i1));
+            case IFEQ:                                  return new If(    new Eq(new Constant(0), pop()), new Label(i1));
+            case IFNE:                                  return new If(new Not(new Eq(new Constant(0), pop())), new Label(i1));
+            case IFLT:                                  return new If(    new Lt(new Constant(0), pop()), new Label(i1));
+            case IFGE:                                  return new If(new Not(new Lt(new Constant(0), pop())), new Label(i1));
+            case IFGT:                                  return new If(    new Gt(new Constant(0), pop()), new Label(i1));
+            case IFLE:                                  return new If(new Not(new Gt(new Constant(0), pop())), new Label(i1));
+            case IF_ICMPEQ:                             return new If(    new Eq(pop(), pop()), new Label(i1));
+            case IF_ICMPNE:                             return new If(new Not(new Eq(pop(), pop())), new Label(i1));
+            case IF_ICMPLT:                             return new If(    new Lt(pop(), pop()), new Label(i1));
+            case IF_ICMPGE:                             return new If(new Not(new Lt(pop(), pop())), new Label(i1));
+            case IF_ICMPGT:                             return new If(    new Gt(pop(), pop()), new Label(i1));
+            case IF_ICMPLE:                             return new If(new Not(new Gt(pop(), pop())), new Label(i1));
+            case IF_ACMPEQ:                             return new If(    new Eq(pop(), pop()), new Label(i1));
+            case IF_ACMPNE:                             return new If(new Not(new Eq(pop(), pop())), new Label(i1));
+            case ATHROW:                                                       return new Throw(pop());
+            case GOTO:                                                         return new Goto(locals[pc][i1]);
+            case JSR:                                   push(new Label(pc));   return new JSR(new Label(i1));
+            case RET:                                                          return new RET(pop());
+            case RETURN:                                                       return new Return();
             case IRETURN: case LRETURN: case FRETURN: case DRETURN: case ARETURN:
                 return new Return(pop());
 
                 // Array manipulations //////////////////////////////////////////////////////////////////////////////
 
             case IALOAD:  case LALOAD:  case FALOAD:  case DALOAD:  case AALOAD:
-            case BALOAD:  case CALOAD:  case SALOAD:                                  push(new ArrayGet(pop(), pop())); return null;
+            case BALOAD:  case CALOAD:  case SALOAD:
+                return seqPush(new ArrayGet(pop(), pop()));
             case IASTORE: case LASTORE: case FASTORE: case DASTORE: case AASTORE:
-            case BASTORE: case CASTORE: case SASTORE:                                 return new ArrayPut(pop(), pop(), pop());
+            case BASTORE: case CASTORE: case SASTORE:
+                return new ArrayPut(pop(), pop(), pop());
 
                 // Invocation //////////////////////////////////////////////////////////////////////////////
 
@@ -564,60 +693,44 @@ public class JSSA extends MethodGen implements CGConst {
                     case INVOKESTATIC:    ret = new InvokeStatic(method, args); break;
                     default: throw new Error("should never happen");
                 }
-                if(ret.getType() != Type.VOID) push(ret);
-                return ret;
+                if (ret.getType() != Type.VOID) push(ret);
+                return new Seq(ret);
             }
 
                 // Field Access //////////////////////////////////////////////////////////////////////////////
 
-            case GETSTATIC:         push(new Get((Type.Class.Field)arg, null)); return null;
+            case GETSTATIC:         return seqPush(new Get((Type.Class.Field)arg, null));
             case PUTSTATIC:         return new Put((Type.Class.Field)arg, pop(), null);
-            case GETFIELD:          push(new Get((Type.Class.Field)arg, pop())); return null;
+            case GETFIELD:          return seqPush(new Get((Type.Class.Field)arg, pop()));
             case PUTFIELD:          return new Put((Type.Class.Field)arg, pop(), pop());
 
                 // Allocation //////////////////////////////////////////////////////////////////////////////
 
             case NEW:               push(new New((Type.Class)arg)); return null;
-            case NEWARRAY: {
-                Type base;
-                switch(((Integer)arg).intValue()) {
-                    case 4: base = Type.BOOLEAN; break;
-                    case 5: base = Type.CHAR; break;
-                    case 6: base = Type.FLOAT; break;
-                    case 7: base = Type.DOUBLE; break;
-                    case 8: base = Type.BYTE; break;
-                    case 9: base = Type.SHORT; break;
-                    case 10: base = Type.INT; break;
-                    case 11: base = Type.LONG; break;
-                    default: throw new IllegalStateException("invalid array type");
-                }
-                push(new NewArray(base.makeArray(),pop()));
-                return null;
-            }
+            case NEWARRAY:          return seqPush(new NewArray(Type.fromArraySpec(((Integer)arg).intValue()).makeArray(), pop()));
             case ANEWARRAY:         push(new NewArray(((Type.Ref)arg).makeArray(), pop())); return null;
             case MULTIANEWARRAY: {
                 MethodGen.MultiANewArray mana = (MethodGen.MultiANewArray) arg;
                 Expr[] dims = new Expr[mana.dims];
                 for(int i=0;i<dims.length;i++) dims[i] = pop();
-                push(new NewArray(mana.type, dims));
-                return null;
+                return seqPush(new NewArray(mana.type, dims));
             }
-            case ARRAYLENGTH:       push(new ArrayLength(pop())); return null;
+            case ARRAYLENGTH:       return seqPush(new ArrayLength(pop()));
 
                 // Runtime Type information //////////////////////////////////////////////////////////////////////////////
 
-            case CHECKCAST:         push(new Cast(pop(), (Type.Ref)arg)); return null;
+            case CHECKCAST:         return seqPush(new Cast(pop(), (Type.Ref)arg));
             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;
 
-            case BIPUSH:    push(new Constant(i1));  // FIXME return null;
-            case SIPUSH:    push(new Constant(i1));  // FIXME return null;
+            case BIPUSH:    push(new Constant((Integer)arg)); return null;
+            case SIPUSH:    push(new Constant((Integer)arg)); return null;
 
-            case TABLESWITCH:    new Branch((MethodGen.Switch)arg);
-            case LOOKUPSWITCH:   new Branch((MethodGen.Switch)arg);
+            case TABLESWITCH:    return new Branch((MethodGen.Switch)arg);
+            case LOOKUPSWITCH:   return new Branch((MethodGen.Switch)arg);
 
-                /*
+                /* FIXME
             case MONITORENTER:   Op.monitorEnter(pop());
             case MONITOREXIT:    Op.monitorExit(pop());
                 */
@@ -637,6 +750,44 @@ public class JSSA extends MethodGen implements CGConst {
         }
     }
 
+    
+    public void debugBodyToString(StringBuffer sb) {
+        StringBuffer sb0 = new StringBuffer();
+        super.debugBodyToString(sb0);
+        StringTokenizer st = new StringTokenizer(sb0.toString(), "\n");
+        String[] lines = new String[st.countTokens()];
+        for(int i=0; i<lines.length; i++) lines[i] = st.nextToken();
+        for(int j=0; j<ofs[0]; j++) {
+            String s = "    /* " + lines[j].trim();
+             while(s.length() < 50) s += " ";
+             s += " */";
+             sb.append(s);
+             sb.append("\n");
+        }
+        
+        bindingMap = new IdentityHashMap();
+        nextVar = 0;
+        
+        for(int i=0; i<numOps; i++) {
+            String s = "    /* " + lines[ofs[i]].trim();
+             while(s.length() < 50) s += " ";
+             s += " */  ";
+             s += ops[i].toString();
+             sb.append(s);
+             sb.append(";\n");
+             for(int j=ofs[i]+1; j<(i==numOps-1?size():ofs[i+1]); j++) {
+                 s = "    /* " + lines[j].trim();
+                  while(s.length() < 50) s += " ";
+                  s += " */";
+                  sb.append(s);
+                  sb.append("\n");
+             }
+        }
+    }
+    
+    private Map bindingMap;
+    private int nextVar;
+    
     public static void main(String[] args) throws Exception {
         InputStream is = Class.forName(args[0]).getClassLoader().getResourceAsStream(args[0].replace('.', '/')+".class");
         System.out.println(new ClassFile(new DataInputStream(is), true).toString());