diff --git a/include/avian/vm/codegen/registers.h b/include/avian/vm/codegen/registers.h
index 317bb2215a..32b005d61a 100644
--- a/include/avian/vm/codegen/registers.h
+++ b/include/avian/vm/codegen/registers.h
@@ -45,6 +45,28 @@ public:
   { }
 };
 
+class RegisterIterator {
+public:
+  int index;
+  const RegisterMask& mask;
+
+  inline RegisterIterator(const RegisterMask& mask):
+    index(mask.start),
+    mask(mask) {}
+
+  inline bool hasNext() {
+    return index < mask.limit;
+  }
+
+  inline int next() {
+    int r = index;
+    do {
+      index++;
+    } while(index < mask.limit && !(mask.mask & (1 << index)));
+    return r;
+  }
+};
+
 } // namespace codegen
 } // namespace avian
 
diff --git a/src/tools/audit-codegen/main.cpp b/src/tools/audit-codegen/main.cpp
index 77f0b36e8a..d201cd43a4 100644
--- a/src/tools/audit-codegen/main.cpp
+++ b/src/tools/audit-codegen/main.cpp
@@ -8,23 +8,80 @@
    There is NO WARRANTY for this software.  See license.txt for
    details. */
 
-#include "system.h"
+#include <avian/vm/system/system.h>
 
 #include <avian/util/arg-parser.h>
 
-#include "codegen/lir.h"
-#include "codegen/assembler.h"
-#include "codegen/targets.h"
+#include <avian/vm/codegen/lir.h>
+#include <avian/vm/codegen/assembler.h>
+#include <avian/vm/codegen/targets.h>
+#include <avian/vm/codegen/registers.h>
+
+#include <avian/vm/heap/heap.h>
 
 // since we aren't linking against libstdc++, we must implement this
 // ourselves:
 extern "C" void __cxa_pure_virtual(void) { abort(); }
 
+using namespace vm;
 using namespace avian::codegen;
 using namespace avian::util;
 
-void generateCode(Assembler::Architecture* arch) {
-  for()
+class BasicEnv {
+public:
+  System* s;
+  Heap* heap;
+  Assembler::Architecture* arch;
+
+  BasicEnv():
+    s(makeSystem(0)),
+    heap(makeHeap(s, 32 * 1024)),
+    arch(makeArchitectureNative(s, true))
+  {
+    arch->acquire();
+  }
+
+  ~BasicEnv() {
+    arch->release();
+    s->dispose();
+  }
+};
+
+class Asm {
+public:
+  Zone zone;
+  Assembler* a;
+
+  Asm(BasicEnv& env):
+    zone(env.s, env.heap, 8192),
+    a(env.arch->makeAssembler(env.heap, &zone))
+  { }
+
+  ~Asm() {
+    a->dispose();
+  }
+};
+
+void generateCode(BasicEnv& env) {
+  Asm a(env);
+  for(RegisterIterator it(env.arch->registerFile()->generalRegisters); it.hasNext(); ) {
+    int r = it.next();
+    lir::Register reg(r);
+    a.a->apply(lir::Add,
+      OperandInfo(4, lir::RegisterOperand, &reg),
+      OperandInfo(4, lir::RegisterOperand, &reg),
+      OperandInfo(4, lir::RegisterOperand, &reg));
+  }
+  unsigned length = a.a->endBlock(false)->resolve(0, 0);
+  printf("length: %d\n", length);
+  uint8_t* data = static_cast<uint8_t*>(env.s->tryAllocate(length));
+  a.a->setDestination(data);
+  a.a->write();
+  for(unsigned i = 0; i < length; i++) {
+    printf("%02x ", data[i]);
+  }
+  printf("\n");
+  env.s->free(data);
 }
 
 class Arguments {
@@ -51,13 +108,9 @@ public:
 int main(int argc, char** argv) {
   Arguments args(argc, argv);
 
-  vm::System* s = vm::makeSystem(0);
-  Assembler::Architecture* arch = makeArchitectureNative(s, true);
-  arch->acquire();
+  BasicEnv env;
 
-  generateCode(arch);
+  generateCode(env);
 
-  arch->release();
-  s->dispose();
   return 0;
 }
\ No newline at end of file
diff --git a/unittest/codegen/registers-test.cpp b/unittest/codegen/registers-test.cpp
new file mode 100644
index 0000000000..946e45ebab
--- /dev/null
+++ b/unittest/codegen/registers-test.cpp
@@ -0,0 +1,44 @@
+/* Copyright (c) 2008-2011, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+#include <stdio.h>
+
+#include <avian/vm/codegen/registers.h>
+
+#include "test-harness.h"
+
+
+using namespace avian::codegen;
+using namespace vm;
+
+
+class RegisterIteratorTest : public Test {
+public:
+  RegisterIteratorTest():
+    Test("RegisterIterator")
+  {}
+
+  virtual void run() {
+    RegisterMask regs(0x55);
+    assertEqual<unsigned>(0, regs.start);
+    assertEqual<unsigned>(7, regs.limit);
+
+    RegisterIterator it(regs);
+    assertTrue(it.hasNext());
+    assertEqual<unsigned>(0, it.next());
+    assertTrue(it.hasNext());
+    assertEqual<unsigned>(2, it.next());
+    assertTrue(it.hasNext());
+    assertEqual<unsigned>(4, it.next());
+    assertTrue(it.hasNext());
+    assertEqual<unsigned>(6, it.next());
+    assertFalse(it.hasNext());
+  }
+} registerIteratorTest;