diff -r a350c2cc736a -r 75e385f68b7e jitcraft/Opcodes.cpp
--- a/jitcraft/Opcodes.cpp	Fri Jun 29 19:35:17 2012 -0700
+++ b/jitcraft/Opcodes.cpp	Sat Jun 30 19:38:53 2012 -0700
@@ -18,6 +18,9 @@
 #include "Opcodes.h"
 #include "Utility.h"
 #include "Code.h"
+#include "Zone.h"
+#include "Array.h"
+#include "Heap-inl.h"
 
 using namespace jc;
 
@@ -29,6 +32,31 @@
 #undef OPDEF
 };
 
+void
+Code::init(ByteArray *bytecode, FixedArray *locals, FixedArray *args,
+           FixedArray *maps, unsigned maxStackDepth, Module *module)
+{
+    WRITE_FIELD_OBJ_NO_BARRIER(bytecode, bytecode);
+    WRITE_FIELD_OBJ_NO_BARRIER(locals, locals);
+    WRITE_FIELD_OBJ_NO_BARRIER(args, args);
+    WRITE_FIELD_OBJ_NO_BARRIER(maps, maps);
+    WRITE_FIELD(maxStackDepth, maxStackDepth);
+    WRITE_FIELD(module, VoidPtr(module));
+}
+
+Code *
+Code::New(Zone *zone, ByteArray *bytecode, FixedArray *locals, FixedArray *args,
+          FixedArray *maps, unsigned maxStackDepth, Module *module)
+{
+    Object *obj = zone->allocate(MapKind_Code, sizeof(Code), Heap::Tenure_Old);
+    if (!obj)
+        return NULL;
+
+    Code *code = Code::cast(obj);
+    code->init(bytecode, locals, args, maps, maxStackDepth, module);
+    return code;
+}
+
 // All jumps must be the same length.
 STATIC_ASSERT(OP_JL_LENGTH == OP_JUMP_LENGTH);
 STATIC_ASSERT(OP_JLE_LENGTH == OP_JUMP_LENGTH);
@@ -99,26 +127,26 @@
             fprintf(fp, "%u (%+d)", unsigned((pc + READ_INT32(pc)) - code->start()), READ_INT32(pc));
             break;
 
-          case OP_STACKARRAY:
+          case OP_LIFOARRAY:
           {
-            unsigned width = pc[1];
-            unsigned dims = pc[2];
-
-            for (unsigned i = 0; i < dims; i++)
-                fprintf(fp, "[%u]", READ_UINT32(pc + 2 + (i * sizeof(unsigned))));
-            fprintf(fp, " ; (width = %s)\n", (width == 1 ? "char" : "cell"));
-            pc += 3 + dims * sizeof(unsigned);
-            continue;
+            // :TODO: use Local
+            ArrayMap *map = ArrayMap::cast(code->map(READ_UINT32(pc)));
+            fprintf(fp, "%s:", map->type()->innermost()->tag()
+                               ? map->type()->innermost()->tag()
+                               : "_");
+            for (; map; map = map->contained()) {
+                Type *type = map->type();
+                fprintf(fp, "[%d]", type->elements());
+            }
+            break;
           }
 
           case OP_GETLOCAL:
           case OP_SETLOCAL:
           case OP_GETARG:
           case OP_SETARG:
-          case OP_UNWIND:
-            fprintf(fp, "%u", READ_UINT32(pc));
-            break;
-
+          case OP_SAVELIFO:
+          case OP_UNWINDLIFO:
           case OP_CALLGLOBAL:
             fprintf(fp, "%u", READ_UINT32(pc));
             break;
@@ -131,5 +159,6 @@
 
         fprintf(fp, "\n");
         pc += OpcodeInfo[op].length;
+        assert(pc < code->start() + code->length());
     }
 }