diff -r 75e385f68b7e -r 627b6b94e774 jitcraft/Code.h
--- a/jitcraft/Code.h	Sat Jun 30 19:38:53 2012 -0700
+++ b/jitcraft/Code.h	Sat Jun 30 20:20:39 2012 -0700
@@ -29,31 +29,17 @@
 class Module;
 class Type;
 
+// A code object contains the bytecode compiled from a function (or global
+// script), as well as all information needed to interpret or JIT-compile
+// the bytecode.
 class Code : public Object
 {
-    OBJECT_FIELD(ByteArray *, bytecode);
-    OBJECT_FIELD(FixedArray *, locals);
-    OBJECT_FIELD(FixedArray *, args);
-    OBJECT_FIELD(uint32, maxStackDepth);
-    OBJECT_FIELD(VoidPtr, module);
-    OBJECT_FIELD(FixedArray *, maps);
-
-  private:
-    void init(ByteArray *bytecode, FixedArray *locals, FixedArray *args,
-              FixedArray *maps, unsigned maxStackDepth, Module *module);
-
-    ByteArray *code() {
-        return ByteArray::cast(READ_FIELD_OBJ(bytecode));
-    }
-    FixedArray *locals() {
-        return FixedArray::cast(READ_FIELD_OBJ(locals));
-    }
-    FixedArray *args() {
-        return FixedArray::cast(READ_FIELD_OBJ(args));
-    }
-    FixedArray *maps() {
-        return FixedArray::cast(READ_FIELD_OBJ(maps));
-    }
+    Module *module_;
+    Unbarriered<ByteArray> bytecode_;
+    Unbarriered<FixedArray> locals_;
+    Unbarriered<FixedArray> args_;
+    Unbarriered<FixedArray> maps_;
+    unsigned maxStackDepth_;
 
   public:
     // :TODO: use handles
@@ -61,33 +47,31 @@
                      FixedArray *maps, unsigned maxStackDepth, Module *module);
 
     Module *module() {
-        return (Module *)READ_FIELD(module);
+        return module_;
     }
     bytecode *start() {
-        return code()->raw();
+        return bytecode_->raw();
     }
     unsigned length() {
-        return code()->length();
+        return bytecode_->length();
     }
     Type *localType(size_t index) {
-        assert(index < nlocals());
-        return Type::cast(locals()->at(index));
+        return Type::cast(locals_->at(index));
     }
     Type *argType(size_t index) {
-        assert(index < nlocals());
-        return Type::cast(args()->at(index));
+        return Type::cast(args_->at(index));
     }
     unsigned nlocals() {
-        return locals()->length();
+        return locals_->length();
     }
     unsigned nargs() {
-        return args()->length();
+        return args_->length();
     }
     unsigned maxStackDepth() {
-        return READ_FIELD(maxStackDepth);
+        return maxStackDepth_;
     }
     Map *map(size_t index) {
-        return Map::cast(maps()->at(index));
+        return Map::cast(maps_->at(index));
     }
 
     static Code *cast(Object *obj) {