#include "jnienv.h"
#include "machine.h"
#include "util.h"
#include "stream.h"
#include "constants.h"
#include "processor.h"

using namespace vm;

namespace {

bool
find(Thread* t, Thread* o)
{
  if (t == o) return true;

  for (Thread* p = t->peer; p; p = p->peer) {
    if (p == o) return true;
  }

  if (t->child) return find(t->child, o);

  return false;
}

void
join(Thread* t, Thread* o)
{
  if (t != o) {
    o->systemThread->join();
    o->state = Thread::JoinedState;
  }
}

unsigned
count(Thread* t, Thread* o)
{
  unsigned c = 0;

  if (t != o) ++ c;

  for (Thread* p = t->peer; p; p = p->peer) {
    c += count(p, o);
  }
  
  if (t->child) c += count(t->child, o);

  return c;
}

Thread**
fill(Thread* t, Thread* o, Thread** array)
{
  if (t != o) *(array++) = t;

  for (Thread* p = t->peer; p; p = p->peer) {
    array = fill(p, o, array);
  }
  
  if (t->child) array = fill(t->child, o, array);

  return array;
}

void
dispose(Thread* t, Thread* o, bool remove)
{
  if (remove) {
    // debug
    expect(t, find(t->m->rootThread, o));

    unsigned c = count(t->m->rootThread, o);
    Thread* threads[c];
    fill(t->m->rootThread, o, threads);
    // end debug

    if (o->parent) {
      Thread* previous = 0;
      for (Thread* p = o->parent->child; p;) {
        if (p == o) {
          if (p == o->parent->child) {
            o->parent->child = p->peer;
          } else {
            previous->peer = p->peer;
          }
          break;
        } else {
          previous = p;
          p = p->peer;
        }
      }      

      for (Thread* p = o->child; p;) {
        Thread* next = p->peer;
        p->peer = o->parent->child;
        o->parent->child = p;
        p->parent = o->parent;
        p = next;
      }
    } else if (o->child) {
      t->m->rootThread = o->child;

      for (Thread* p = o->peer; p;) {
        Thread* next = p->peer;
        p->peer = t->m->rootThread;
        t->m->rootThread = p;
        p = next;
      }
    } else if (o->peer) {
      t->m->rootThread = o->peer;
    } else {
      abort(t);
    }

    // debug
    expect(t, not find(t->m->rootThread, o));

    for (unsigned i = 0; i < c; ++i) {
      expect(t, find(t->m->rootThread, threads[i]));
    }
    // end debug
  }

  o->dispose();
}

void
joinAll(Thread* m, Thread* o)
{
  for (Thread* p = o->child; p;) {
    Thread* child = p;
    p = p->peer;
    joinAll(m, child);
  }

  join(m, o);
}

void
disposeAll(Thread* m, Thread* o)
{
  for (Thread* p = o->child; p;) {
    Thread* child = p;
    p = p->peer;
    disposeAll(m, child);
  }

  dispose(m, o, false);
}

void
killZombies(Thread* t, Thread* o)
{
  for (Thread* p = o->child; p;) {
    Thread* child = p;
    p = p->peer;
    killZombies(t, child);
  }

  switch (o->state) {
  case Thread::ZombieState:
    join(t, o);
    // fall through

  case Thread::JoinedState:
    dispose(t, o, true);

  default: break;
  }
}

unsigned
footprint(Thread* t)
{
  unsigned n = t->heapOffset + t->heapIndex;

  for (Thread* c = t->child; c; c = c->peer) {
    n += footprint(c);
  }

  return n;
}

void
visitRoots(Thread* t, Heap::Visitor* v)
{
  if (t->state != Thread::ZombieState) {
    v->visit(&(t->javaThread));
    v->visit(&(t->exception));

    t->m->processor->visitObjects(t, v);

    for (Thread::Protector* p = t->protector; p; p = p->next) {
      p->visit(v);
    }
  }

  for (Thread* c = t->child; c; c = c->peer) {
    visitRoots(c, v);
  }
}

void
walk(Thread*, Heap::Walker* w, uint32_t* mask, unsigned fixedSize,
     unsigned arrayElementSize, unsigned arrayLength)
{
  unsigned fixedSizeInWords = ceiling(fixedSize, BytesPerWord);
  unsigned arrayElementSizeInWords
    = ceiling(arrayElementSize, BytesPerWord);

  for (unsigned i = 0; i < fixedSizeInWords; ++i) {
    if (mask[i / 32] & (static_cast<uint32_t>(1) << (i % 32))) {
      if (not w->visit(i)) {
        return;
      }
    }
  }

  bool arrayObjectElements = false;
  for (unsigned j = 0; j < arrayElementSizeInWords; ++j) {
    unsigned k = fixedSizeInWords + j;
    if (mask[k / 32] & (static_cast<uint32_t>(1) << (k % 32))) {
      arrayObjectElements = true;
      break;
    }
  }

  if (arrayObjectElements) {
    for (unsigned i = 0; i < arrayLength; ++i) {
      for (unsigned j = 0; j < arrayElementSizeInWords; ++j) {
        unsigned k = fixedSizeInWords + j;
        if (mask[k / 32] & (static_cast<uint32_t>(1) << (k % 32))) {
          if (not w->visit
              (fixedSizeInWords + (i * arrayElementSizeInWords) + j))
          {
            return;
          }
        }
      }
    }
  }
}

void
walk(Thread* t, Heap::Walker* w, object o)
{
  object class_ = static_cast<object>(t->m->heap->follow(objectClass(t, o)));
  object objectMask = static_cast<object>
    (t->m->heap->follow(classObjectMask(t, class_)));

  if (objectMask) {
    unsigned fixedSize = classFixedSize(t, class_);
    unsigned arrayElementSize = classArrayElementSize(t, class_);
    unsigned arrayLength
      = (arrayElementSize ?
         cast<uintptr_t>(o, fixedSize - BytesPerWord) : 0);

    uint32_t mask[intArrayLength(t, objectMask)];
    memcpy(mask, &intArrayBody(t, objectMask, 0),
           intArrayLength(t, objectMask) * 4);

    walk(t, w, mask, fixedSize, arrayElementSize, arrayLength);
  } else if (classVmFlags(t, class_) & SingletonFlag) {
    unsigned length = singletonLength(t, o);
    if (length) {
      walk(t, w, singletonMask(t, o),
           (singletonCount(t, o) + 2) * BytesPerWord, 0, 0);
    } else {
      w->visit(0);
    }
  } else {
    w->visit(0);
  }
}

void
finalizerTargetUnreachable(Thread* t, Heap::Visitor* v, object* p)
{
  v->visit(&finalizerTarget(t, *p));

  object finalizer = *p;
  *p = finalizerNext(t, finalizer);
  finalizerNext(t, finalizer) = t->m->finalizeQueue;
  t->m->finalizeQueue = finalizer;
}

void
referenceTargetUnreachable(Thread* t, Heap::Visitor* v, object* p)
{
  if (DebugReferences) {
    fprintf(stderr, "target %p unreachable for reference %p\n",
            jreferenceTarget(t, *p), *p);
  }

  v->visit(p);
  jreferenceTarget(t, *p) = 0;

  if (jreferenceQueue(t, *p)
      and t->m->heap->status(jreferenceQueue(t, *p)) != Heap::Unreachable)
  {
    // queue is reachable - add the reference

    v->visit(&jreferenceQueue(t, *p));

    object q = jreferenceQueue(t, *p);

    set(t, *p, JreferenceJNext, *p);
    if (referenceQueueFront(t, q)) {
      set(t, referenceQueueRear(t, q), JreferenceJNext, *p);
    } else {
      set(t, q, ReferenceQueueFront, *p);
    }
    set(t, q, ReferenceQueueRear, *p);

    jreferenceQueue(t, *p) = 0;
  }

  *p = jreferenceVmNext(t, *p);
}

void
referenceUnreachable(Thread* t, Heap::Visitor* v, object* p)
{
  if (DebugReferences) {
    fprintf(stderr, "reference %p unreachable (target %p)\n",
            *p, jreferenceTarget(t, *p));
  }

  if (jreferenceQueue(t, *p)
      and t->m->heap->status(jreferenceQueue(t, *p)) != Heap::Unreachable)
  {
    // queue is reachable - add the reference
    referenceTargetUnreachable(t, v, p);    
  } else {
    *p = jreferenceVmNext(t, *p);
  }
}

void
referenceTargetReachable(Thread* t, Heap::Visitor* v, object* p)
{
  if (DebugReferences) {
    fprintf(stderr, "target %p reachable for reference %p\n",
            jreferenceTarget(t, *p), *p);
  }

  v->visit(p);
  v->visit(&jreferenceTarget(t, *p));

  if (t->m->heap->status(jreferenceQueue(t, *p)) == Heap::Unreachable) {
    jreferenceQueue(t, *p) = 0;
  } else {
    v->visit(&jreferenceQueue(t, *p));
  }
}

void
postVisit(Thread* t, Heap::Visitor* v)
{
  Machine* m = t->m;
  bool major = m->heap->collectionType() == Heap::MajorCollection;

  for (object* p = &(m->finalizeQueue); *p; p = &(finalizerNext(t, *p))) {
    v->visit(p);
    v->visit(&finalizerTarget(t, *p));
  }

  for (object* p = &(m->finalizeQueue); *p; p = &(finalizerNext(t, *p))) {
    v->visit(p);
    v->visit(&finalizerTarget(t, *p));
  }

  object firstNewTenuredFinalizer = 0;
  object lastNewTenuredFinalizer = 0;

  for (object* p = &(m->finalizers); *p;) {
    v->visit(p);

    if (m->heap->status(finalizerTarget(t, *p)) == Heap::Unreachable) {
      // target is unreachable - queue it up for finalization
      finalizerTargetUnreachable(t, v, p);
    } else {
      // target is reachable
      v->visit(&finalizerTarget(t, *p));

      if (m->heap->status(*p) == Heap::Tenured) {
        // the finalizer is tenured, so we remove it from
        // m->finalizers and later add it to m->tenuredFinalizers

        if (lastNewTenuredFinalizer == 0) {
          lastNewTenuredFinalizer = *p;
        }

        object finalizer = *p;
        *p = finalizerNext(t, finalizer);
        finalizerNext(t, finalizer) = firstNewTenuredFinalizer;
        firstNewTenuredFinalizer = finalizer;
      } else {
        p = &finalizerNext(t, *p);
      }
    }
  }

  object firstNewTenuredWeakReference = 0;
  object lastNewTenuredWeakReference = 0;

  for (object* p = &(m->weakReferences); *p;) {
    if (m->heap->status(*p) == Heap::Unreachable) {
      // reference is unreachable
      referenceUnreachable(t, v, p);
    } else if (m->heap->status(jreferenceTarget(t, *p))
               == Heap::Unreachable)
    {
      // target is unreachable
      referenceTargetUnreachable(t, v, p);
    } else {
      // both reference and target are reachable
      referenceTargetReachable(t, v, p);

      if (m->heap->status(*p) == Heap::Tenured) {
        // the reference is tenured, so we remove it from
        // m->weakReferences and later add it to
        // m->tenuredWeakReferences

        if (lastNewTenuredWeakReference == 0) {
          lastNewTenuredWeakReference = *p;
        }

        object reference = *p;
        *p = jreferenceVmNext(t, reference);
        jreferenceVmNext(t, reference) = firstNewTenuredWeakReference;
        firstNewTenuredWeakReference = reference;
      } else {
        p = &jreferenceVmNext(t, *p);
      }
    }
  }

  if (major) {
    for (object* p = &(m->tenuredFinalizers); *p;) {
      v->visit(p);

      if (m->heap->status(finalizerTarget(t, *p)) == Heap::Unreachable) {
        // target is unreachable - queue it up for finalization
        finalizerTargetUnreachable(t, v, p);
      } else {
        // target is reachable
        v->visit(&finalizerTarget(t, *p));
        p = &finalizerNext(t, *p);
      }
    }

    for (object* p = &(m->tenuredWeakReferences); *p;) {
      if (m->heap->status(*p) == Heap::Unreachable) {
        // reference is unreachable
        referenceUnreachable(t, v, p);
      } else if (m->heap->status(jreferenceTarget(t, *p))
                 == Heap::Unreachable)
      {
        // target is unreachable
        referenceTargetUnreachable(t, v, p);
      } else {
        // both reference and target are reachable
        referenceTargetReachable(t, v, p);
        p = &jreferenceVmNext(t, *p);
      }
    }
  }

  if (lastNewTenuredFinalizer) {
    finalizerNext(t, lastNewTenuredFinalizer) = m->tenuredFinalizers;
    m->tenuredFinalizers = firstNewTenuredFinalizer;
  }

  if (lastNewTenuredWeakReference) {
    jreferenceVmNext(t, lastNewTenuredWeakReference) = m->tenuredWeakReferences;
    m->tenuredWeakReferences = firstNewTenuredWeakReference;
  }
}

void
postCollect(Thread* t)
{
#ifdef VM_STRESS
  t->allocator.free(t->defaultHeap, Thread::HeapSizeInBytes);
  t->defaultHeap = static_cast<uintptr_t*>
    (t->allocator.allocate(Thread::HeapSizeInBytes));
#endif

  t->heap = t->defaultHeap;
  t->heapOffset = 0;
  t->heapIndex = 0;

  for (Thread* c = t->child; c; c = c->peer) {
    postCollect(c);
  }
}

object
makeByteArray(Thread* t, const char* format, va_list a)
{
  const int Size = 256;
  char buffer[Size];
  
  int r = vsnprintf(buffer, Size - 1, format, a);
  expect(t, r >= 0 and r < Size - 1);

  object s = makeByteArray(t, strlen(buffer) + 1, false);
  memcpy(&byteArrayBody(t, s, 0), buffer, byteArrayLength(t, s));

  return s;
}

unsigned
mangledSize(int8_t c)
{
  switch (c) {
  case '_':
  case ';':
  case '[':
    return 2;

  case '$':
    return 6;

  default:
    return 1;
  }
}

unsigned
mangle(int8_t c, int8_t* dst)
{
  switch (c) {
  case '/':
    dst[0] = '_';
    return 1;

  case '_':
    dst[0] = '_';
    dst[1] = '1';
    return 2;

  case ';':
    dst[0] = '_';
    dst[1] = '2';
    return 2;

  case '[':
    dst[0] = '_';
    dst[1] = '3';
    return 2;

  case '$':
    memcpy(dst, "_00024", 6);
    return 6;

  default:
    dst[0] = c;    
    return 1;
  }
}

object
makeJNIName(Thread* t, object method, bool decorate)
{
  unsigned size = 5;
  object className = ::className(t, methodClass(t, method));
  PROTECT(t, className);
  for (unsigned i = 0; i < byteArrayLength(t, className) - 1; ++i) {
    size += mangledSize(byteArrayBody(t, className, i));
  }

  ++ size;

  object methodName = ::methodName(t, method);
  PROTECT(t, methodName);
  for (unsigned i = 0; i < byteArrayLength(t, methodName) - 1; ++i) {
    size += mangledSize(byteArrayBody(t, methodName, i));
  }

  object methodSpec = ::methodSpec(t, method);
  PROTECT(t, methodSpec);
  if (decorate) {
    size += 2;
    for (unsigned i = 1; i < byteArrayLength(t, methodSpec) - 1
           and byteArrayBody(t, methodSpec, i) != ')'; ++i)
    {
      size += mangledSize(byteArrayBody(t, methodSpec, i));
    }
  }

  object name = makeByteArray(t, size + 1, false);
  unsigned index = 0;

  memcpy(&byteArrayBody(t, name, index), "Java_", 5);
  index += 5;

  for (unsigned i = 0; i < byteArrayLength(t, className) - 1; ++i) {
    index += mangle(byteArrayBody(t, className, i),
                    &byteArrayBody(t, name, index));
  }

  byteArrayBody(t, name, index++) = '_';

  for (unsigned i = 0; i < byteArrayLength(t, methodName) - 1; ++i) {
    index += mangle(byteArrayBody(t, methodName, i),
                    &byteArrayBody(t, name, index));
  }
  
  if (decorate) {
    byteArrayBody(t, name, index++) = '_';
    byteArrayBody(t, name, index++) = '_';
    for (unsigned i = 1; i < byteArrayLength(t, methodSpec) - 1
           and byteArrayBody(t, methodSpec, i) != ')'; ++i)
    {
      index += mangle(byteArrayBody(t, methodSpec, i),
                      &byteArrayBody(t, name, index));
    }
  }

  byteArrayBody(t, name, index++) = 0;

  assert(t, index == size + 1);

  return name;
}

object
parseUtf8(Thread* t, Stream& s, unsigned length)
{
  object value = makeByteArray(t, length + 1, false);
  unsigned vi = 0;
  for (unsigned si = 0; si < length; ++si) {
    unsigned a = s.read1();
    if (a & 0x80) {
      // todo: handle non-ASCII characters properly
      if (a & 0x20) {
	// 3 bytes
	si += 2;
	assert(t, si < length);
	/*unsigned b = */s.read1();
	/*unsigned c = */s.read1();
	byteArrayBody(t, value, vi++) = '_';
      } else {
	// 2 bytes
	++ si;
	assert(t, si < length);
	unsigned b = s.read1();

	if (a == 0xC0 and b == 0x80) {
	  byteArrayBody(t, value, vi++) = 0;
	} else {
	  byteArrayBody(t, value, vi++) = '_';
	}
      }
    } else {
      byteArrayBody(t, value, vi++) = a;
    }
  }

  if (vi < length) {
    PROTECT(t, value);
    
    object v = makeByteArray(t, vi + 1, false);
    memcpy(&byteArrayBody(t, v, 0), &byteArrayBody(t, value, 0), vi);
    value = v;
  }
  
  byteArrayBody(t, value, vi) = 0;
  return value;
}

unsigned
parsePoolEntry(Thread* t, Stream& s, uint32_t* index, object pool, unsigned i)
{
  PROTECT(t, pool);

  s.setPosition(index[i]);

  switch (s.read1()) {
  case CONSTANT_Integer:
  case CONSTANT_Float: {
    singletonValue(t, pool, i) = s.read4();
  } return 1;
    
  case CONSTANT_Long:
  case CONSTANT_Double: {
    uint64_t v = s.read8();
    memcpy(&singletonValue(t, pool, i), &v, 8);
  } return 2;

  case CONSTANT_Utf8: {
    if (singletonObject(t, pool, i) == 0) {
      object value = parseUtf8(t, s, s.read2());
      set(t, pool, SingletonBody + (i * BytesPerWord), value);
    }
  } return 1;

  case CONSTANT_Class: {
    if (singletonObject(t, pool, i) == 0) {
      unsigned si = s.read2() - 1;
      parsePoolEntry(t, s, index, pool, si);
        
      object value = singletonObject(t, pool, si);
      set(t, pool, SingletonBody + (i * BytesPerWord), value);
    }
  } return 1;

  case CONSTANT_String: {
    if (singletonObject(t, pool, i) == 0) {
      unsigned si = s.read2() - 1;
      parsePoolEntry(t, s, index, pool, si);
        
      object value = singletonObject(t, pool, si);
      value = makeString(t, value, 0, byteArrayLength(t, value) - 1, 0);
      value = intern(t, value);
      set(t, pool, SingletonBody + (i * BytesPerWord), value);
    }
  } return 1;

  case CONSTANT_NameAndType: {
    if (singletonObject(t, pool, i) == 0) {
      unsigned ni = s.read2() - 1;
      unsigned ti = s.read2() - 1;

      parsePoolEntry(t, s, index, pool, ni);
      parsePoolEntry(t, s, index, pool, ti);
        
      object name = singletonObject(t, pool, ni);
      object type = singletonObject(t, pool, ti);
      object value = makePair(t, name, type);
      set(t, pool, SingletonBody + (i * BytesPerWord), value);
    }
  } return 1;

  case CONSTANT_Fieldref:
  case CONSTANT_Methodref:
  case CONSTANT_InterfaceMethodref: {
    if (singletonObject(t, pool, i) == 0) {
      unsigned ci = s.read2() - 1;
      unsigned nti = s.read2() - 1;

      parsePoolEntry(t, s, index, pool, ci);
      parsePoolEntry(t, s, index, pool, nti);
        
      object class_ = singletonObject(t, pool, ci);
      object nameAndType = singletonObject(t, pool, nti);
      object value = makeReference
          (t, class_, pairFirst(t, nameAndType), pairSecond(t, nameAndType));
      set(t, pool, SingletonBody + (i * BytesPerWord), value);
    }
  } return 1;

  default: abort(t);
  }
}

object
parsePool(Thread* t, Stream& s)
{
  unsigned count = s.read2() - 1;

  object pool = makeSingleton(t, count);
  PROTECT(t, pool);

  if (count) {
    uint32_t* index = static_cast<uint32_t*>
      (t->m->heap->allocate(count * 4, false));

    for (unsigned i = 0; i < count; ++i) {
      index[i] = s.position();

      switch (s.read1()) {
      case CONSTANT_Class:
      case CONSTANT_String:
        singletonMarkObject(t, pool, i);
        s.skip(2);
        break;

      case CONSTANT_Integer:
      case CONSTANT_Float:
        s.skip(4);
        break;

      case CONSTANT_NameAndType:
      case CONSTANT_Fieldref:
      case CONSTANT_Methodref:
      case CONSTANT_InterfaceMethodref:
        singletonMarkObject(t, pool, i);
        s.skip(4);
        break;

      case CONSTANT_Long:
      case CONSTANT_Double:
        s.skip(8);
        ++ i;
        break;

      case CONSTANT_Utf8:
        singletonMarkObject(t, pool, i);
        s.skip(s.read2());
        break;

      default: abort(t);
      }
    }

    unsigned end = s.position();

    for (unsigned i = 0; i < count;) {
      i += parsePoolEntry(t, s, index, pool, i);
    }

    t->m->heap->free(index, count * 4, false);

    s.setPosition(end);
  }

  return pool;
}

void
addInterfaces(Thread* t, object class_, object map)
{
  object table = classInterfaceTable(t, class_);
  if (table) {
    unsigned increment = 2;
    if (classFlags(t, class_) & ACC_INTERFACE) {
      increment = 1;
    }

    PROTECT(t, map);
    PROTECT(t, table);

    for (unsigned i = 0; i < arrayLength(t, table); i += increment) {
      object interface = arrayBody(t, table, i);
      object name = className(t, interface);
      hashMapInsertMaybe(t, map, name, interface, byteArrayHash,
                         byteArrayEqual);
    }
  }
}

void
parseInterfaceTable(Thread* t, Stream& s, object class_, object pool)
{
  PROTECT(t, class_);
  PROTECT(t, pool);
  
  object map = makeHashMap(t, 0, 0);
  PROTECT(t, map);

  if (classSuper(t, class_)) {
    addInterfaces(t, classSuper(t, class_), map);
  }

  unsigned count = s.read2();
  for (unsigned i = 0; i < count; ++i) {
    object name = singletonObject(t, pool, s.read2() - 1);
    PROTECT(t, name);

    object interface = resolveClass(t, name);
    PROTECT(t, interface);

    hashMapInsertMaybe(t, map, name, interface, byteArrayHash, byteArrayEqual);

    addInterfaces(t, interface, map);
  }

  object interfaceTable = 0;
  if (hashMapSize(t, map)) {
    unsigned length = hashMapSize(t, map) ;
    if ((classFlags(t, class_) & ACC_INTERFACE) == 0) {
      length *= 2;
    }
    interfaceTable = makeArray(t, length, true);
    PROTECT(t, interfaceTable);

    unsigned i = 0;
    object it = hashMapIterator(t, map);
    PROTECT(t, it);

    for (; it; it = hashMapIteratorNext(t, it)) {
      object interface = resolveClass
        (t, tripleFirst(t, hashMapIteratorNode(t, it)));
      if (UNLIKELY(t->exception)) return;

      set(t, interfaceTable, ArrayBody + (i * BytesPerWord), interface);
      ++ i;

      if ((classFlags(t, class_) & ACC_INTERFACE) == 0) {
        if (classVirtualTable(t, interface)) {
          // we'll fill in this table in parseMethodTable():
          object vtable = makeArray
            (t, arrayLength(t, classVirtualTable(t, interface)), true);
          
          set(t, interfaceTable, ArrayBody + (i * BytesPerWord), vtable);
        }

        ++i;
      }
    }
  }

  set(t, class_, ClassInterfaceTable, interfaceTable);
}

void
parseFieldTable(Thread* t, Stream& s, object class_, object pool)
{
  PROTECT(t, class_);
  PROTECT(t, pool);

  unsigned memberOffset = BytesPerWord;
  if (classSuper(t, class_)) {
    memberOffset = classFixedSize(t, classSuper(t, class_));
  }

  unsigned count = s.read2();
  if (count) {
    unsigned staticOffset = BytesPerWord * 2;
    unsigned staticCount = 0;
  
    object fieldTable = makeArray(t, count, true);
    PROTECT(t, fieldTable);

    object staticValueTable = makeIntArray(t, count, false);
    PROTECT(t, staticValueTable);

    uint8_t staticTypes[count];

    for (unsigned i = 0; i < count; ++i) {
      unsigned flags = s.read2();
      unsigned name = s.read2();
      unsigned spec = s.read2();

      unsigned value = 0;

      unsigned code = fieldCode
        (t, byteArrayBody(t, singletonObject(t, pool, spec - 1), 0));

      unsigned attributeCount = s.read2();
      for (unsigned j = 0; j < attributeCount; ++j) {
        object name = singletonObject(t, pool, s.read2() - 1);
        unsigned length = s.read4();

        if (strcmp(reinterpret_cast<const int8_t*>("ConstantValue"),
                   &byteArrayBody(t, name, 0)) == 0)
        {
          value = s.read2();
        } else {
          s.skip(length);
        }
      }

      object field = makeField
        (t,
         0, // vm flags
         code,
         flags,
         0, // offset
         singletonObject(t, pool, name - 1),
         singletonObject(t, pool, spec - 1),
         class_);

      if (flags & ACC_STATIC) {
        unsigned size = fieldSize(t, code);
        unsigned excess = staticOffset % size;
        if (excess) {
          staticOffset += BytesPerWord - excess;
        }

        fieldOffset(t, field) = staticOffset;

        staticOffset += size;

        intArrayBody(t, staticValueTable, staticCount) = value;

        staticTypes[staticCount++] = code;
      } else {
        if (value) {
          abort(t); // todo: handle non-static field initializers
        }

        unsigned excess = memberOffset % fieldSize(t, code);
        if (excess) {
          memberOffset += BytesPerWord - excess;
        }

        fieldOffset(t, field) = memberOffset;
        memberOffset += fieldSize(t, code);
      }

      set(t, fieldTable, ArrayBody + (i * BytesPerWord), field);
    }

    set(t, class_, ClassFieldTable, fieldTable);

    if (staticCount) {
      unsigned footprint = ceiling(staticOffset - (BytesPerWord * 2),
                                   BytesPerWord);
      object staticTable = makeSingleton(t, footprint);

      uint8_t* body = reinterpret_cast<uint8_t*>
        (&singletonBody(t, staticTable, 0));

      for (unsigned i = 0, offset = 0; i < staticCount; ++i) {
        unsigned size = fieldSize(t, staticTypes[i]);
        unsigned excess = offset % size;
        if (excess) {
          offset += BytesPerWord - excess;
        }

        unsigned value = intArrayBody(t, staticValueTable, i);
        if (value) {
          switch (staticTypes[i]) {
          case ByteField:
          case BooleanField:
            body[offset] = singletonValue(t, pool, value - 1);
            break;

          case CharField:
          case ShortField:
            *reinterpret_cast<uint16_t*>(body + offset)
              = singletonValue(t, pool, value - 1);
            break;

          case IntField:
          case FloatField:
            *reinterpret_cast<uint32_t*>(body + offset)
              = singletonValue(t, pool, value - 1);
            break;

          case LongField:
          case DoubleField:
            memcpy(body + offset, &singletonValue(t, pool, value - 1), 8);
            break;

          case ObjectField:
            memcpy(body + offset,
                   &singletonObject(t, pool, value - 1),
                   BytesPerWord);
            break;

          default: abort(t);
          }
        } else {
          memset(body + offset, 0, size);
        }

        if (staticTypes[i] == ObjectField) {
          singletonMarkObject(t, staticTable, offset / BytesPerWord);
        }

        offset += size;
      }

      set(t, class_, ClassStaticTable, staticTable);
    }
  }

  classFixedSize(t, class_) = pad(memberOffset);
  
  if (classSuper(t, class_)
      and memberOffset == classFixedSize(t, classSuper(t, class_)))
  {
    set(t, class_, ClassObjectMask,
        classObjectMask(t, classSuper(t, class_)));
  } else {
    object mask = makeIntArray
      (t, ceiling(classFixedSize(t, class_), 32 * BytesPerWord), true);
    intArrayBody(t, mask, 0) = 1;

    object superMask = 0;
    if (classSuper(t, class_)) {
      superMask = classObjectMask(t, classSuper(t, class_));
      if (superMask) {
        memcpy(&intArrayBody(t, mask, 0),
               &intArrayBody(t, superMask, 0),
               ceiling(classFixedSize(t, classSuper(t, class_)),
                       32 * BytesPerWord)
               * 4);
      }
    }

    bool sawReferenceField = false;
    object fieldTable = classFieldTable(t, class_);
    if (fieldTable) {
      for (int i = arrayLength(t, fieldTable) - 1; i >= 0; --i) {
        object field = arrayBody(t, fieldTable, i);
        if ((fieldFlags(t, field) & ACC_STATIC) == 0
            and fieldCode(t, field) == ObjectField)
        {
          unsigned index = fieldOffset(t, field) / BytesPerWord;
          intArrayBody(t, mask, (index / 32)) |= 1 << (index % 32);
          sawReferenceField = true;
        }
      }
    }

    if (superMask or sawReferenceField) {
      set(t, class_, ClassObjectMask, mask);
    }
  }
}

object
parseCode(Thread* t, Stream& s, object pool)
{
  PROTECT(t, pool);

  unsigned maxStack = s.read2();
  unsigned maxLocals = s.read2();
  unsigned length = s.read4();

  object code = makeCode(t, pool, 0, 0, maxStack, maxLocals, length, false);
  s.read(&codeBody(t, code, 0), length);
  PROTECT(t, code);

  unsigned ehtLength = s.read2();
  if (ehtLength) {
    object eht = makeExceptionHandlerTable(t, ehtLength, false);
    for (unsigned i = 0; i < ehtLength; ++i) {
      ExceptionHandler* eh = exceptionHandlerTableBody(t, eht, i);
      exceptionHandlerStart(eh) = s.read2();
      exceptionHandlerEnd(eh) = s.read2();
      exceptionHandlerIp(eh) = s.read2();
      exceptionHandlerCatchType(eh) = s.read2();
    }

    set(t, code, CodeExceptionHandlerTable, eht);
  }

  unsigned attributeCount = s.read2();
  for (unsigned j = 0; j < attributeCount; ++j) {
    object name = singletonObject(t, pool, s.read2() - 1);
    unsigned length = s.read4();

    if (strcmp(reinterpret_cast<const int8_t*>("LineNumberTable"),
               &byteArrayBody(t, name, 0)) == 0)
    {
      unsigned lntLength = s.read2();
      object lnt = makeLineNumberTable(t, lntLength, false);
      for (unsigned i = 0; i < lntLength; ++i) {
        LineNumber* ln = lineNumberTableBody(t, lnt, i);
        lineNumberIp(ln) = s.read2();
        lineNumberLine(ln) = s.read2();
      }

      set(t, code, CodeLineNumberTable, lnt);
    } else {
      s.skip(length);
    }
  }

  return code;
}

void
scanMethodSpec(Thread* t, const char* s, unsigned* parameterCount,
               unsigned* returnCode)
{
  unsigned count = 0;
  MethodSpecIterator it(t, s);
  for (; it.hasNext(); it.next()) {
    ++ count;
  }

  *parameterCount = count;
  *returnCode = fieldCode(t, *it.returnSpec());
}

void
parseMethodTable(Thread* t, Stream& s, object class_, object pool)
{
  PROTECT(t, class_);
  PROTECT(t, pool);

  object virtualMap = makeHashMap(t, 0, 0);
  PROTECT(t, virtualMap);

  object nativeMap = makeHashMap(t, 0, 0);
  PROTECT(t, nativeMap);

  unsigned virtualCount = 0;
  unsigned declaredVirtualCount = 0;

  object superVirtualTable = 0;
  PROTECT(t, superVirtualTable);

  if (classFlags(t, class_) & ACC_INTERFACE) {
    object itable = classInterfaceTable(t, class_);
    if (itable) {
      PROTECT(t, itable);
      for (unsigned i = 0; i < arrayLength(t, itable); ++i) {
        object vtable = classVirtualTable(t, arrayBody(t, itable, i));
        if (vtable) {
          PROTECT(t, vtable);
          for (unsigned j = 0; j < arrayLength(t, vtable); ++j) {
            object method = arrayBody(t, vtable, j);
            object n = hashMapFindNode
              (t, virtualMap, method, methodHash, methodEqual);
            if (n == 0) {
              method = makeMethod
                (t,
                 methodVmFlags(t, method),
                 methodReturnCode(t, method),
                 methodParameterCount(t, method),
                 methodParameterFootprint(t, method),
                 methodFlags(t, method),
                 virtualCount++,
                 methodName(t, method),
                 methodSpec(t, method),
                 class_,
                 0,
                 0);
              hashMapInsert(t, virtualMap, method, method, methodHash);
            }
          }
        }
      }
    }
  } else {
    if (classSuper(t, class_)) {
      superVirtualTable = classVirtualTable(t, classSuper(t, class_));
    }

    if (superVirtualTable) {
      virtualCount = arrayLength(t, superVirtualTable);
      for (unsigned i = 0; i < virtualCount; ++i) {
        object method = arrayBody(t, superVirtualTable, i);
        hashMapInsert(t, virtualMap, method, method, methodHash);
      }
    }
  }

  object newVirtuals = makeList(t, 0, 0, 0);
  PROTECT(t, newVirtuals);
  
  unsigned count = s.read2();
  if (count) {
    object methodTable = makeArray(t, count, true);
    PROTECT(t, methodTable);

    for (unsigned i = 0; i < count; ++i) {
      unsigned flags = s.read2();
      unsigned name = s.read2();
      unsigned spec = s.read2();

      object code = 0;
      unsigned attributeCount = s.read2();
      for (unsigned j = 0; j < attributeCount; ++j) {
        object name = singletonObject(t, pool, s.read2() - 1);
        unsigned length = s.read4();

        if (strcmp(reinterpret_cast<const int8_t*>("Code"),
                   &byteArrayBody(t, name, 0)) == 0)
        {
          code = parseCode(t, s, pool);
        } else {
          s.skip(length);
        }
      }

      const char* specString = reinterpret_cast<const char*>
        (&byteArrayBody(t, singletonObject(t, pool, spec - 1), 0));

      unsigned parameterCount;
      unsigned returnCode;
      scanMethodSpec(t, specString, &parameterCount, &returnCode);

      object method =  t->m->processor->makeMethod
        (t,
         0, // vm flags
         returnCode,
         parameterCount,
         parameterFootprint(t, specString, flags & ACC_STATIC),
         flags,
         0, // offset
         singletonObject(t, pool, name - 1),
         singletonObject(t, pool, spec - 1),
         class_,
         code);

      PROTECT(t, method);

      if (methodVirtual(t, method)) {
        ++ declaredVirtualCount;

        object p = hashMapFindNode
          (t, virtualMap, method, methodHash, methodEqual);

        if (p) {
          methodOffset(t, method) = methodOffset(t, tripleFirst(t, p));

          set(t, p, TripleSecond, method);
        } else {
          methodOffset(t, method) = virtualCount++;

          listAppend(t, newVirtuals, method);

          hashMapInsert(t, virtualMap, method, method, methodHash);
        }
      } else {
        methodOffset(t, method) = i;

        if (strcmp(reinterpret_cast<const int8_t*>("<clinit>"), 
                   &byteArrayBody(t, methodName(t, method), 0)) == 0)
        {
          methodVmFlags(t, method) |= ClassInitFlag;
          classVmFlags(t, class_) |= NeedInitFlag;
        }
      }

      if (flags & ACC_NATIVE) {
        object p = hashMapFindNode
          (t, nativeMap, methodName(t, method), byteArrayHash, byteArrayEqual);
        
        if (p) {
          set(t, p, TripleSecond, method);          
        } else {
          hashMapInsert(t, nativeMap, methodName(t, method), 0, byteArrayHash);
        }
      }

      set(t, methodTable, ArrayBody + (i * BytesPerWord), method);
    }

    for (unsigned i = 0; i < count; ++i) {
      object method = arrayBody(t, methodTable, i);

      if (methodFlags(t, method) & ACC_NATIVE) {
        PROTECT(t, method);

        object overloaded = hashMapFind
          (t, nativeMap, methodName(t, method), byteArrayHash, byteArrayEqual);

        object jniName = makeJNIName(t, method, overloaded);
        set(t, method, MethodCode, jniName);
      }
    }

    set(t, class_, ClassMethodTable, methodTable);
  }

  if (declaredVirtualCount == 0
      and (classFlags(t, class_) & ACC_INTERFACE) == 0)
  {
    // inherit virtual table from superclass
    set(t, class_, ClassVirtualTable, superVirtualTable);

    if (classInterfaceTable(t, classSuper(t, class_))
        and arrayLength(t, classInterfaceTable(t, class_))
        == arrayLength(t, classInterfaceTable(t, classSuper(t, class_))))
    {
      // inherit interface table from superclass
      set(t, class_, ClassInterfaceTable,
          classInterfaceTable(t, classSuper(t, class_)));
    }
  } else if (virtualCount) {
    // generate class vtable

    object vtable = makeArray(t, virtualCount, true);

    unsigned i = 0;
    if (classFlags(t, class_) & ACC_INTERFACE) {
      PROTECT(t, vtable);

      for (object it = hashMapIterator(t, virtualMap); it;
           it = hashMapIteratorNext(t, it))
      {
        object method = tripleFirst(t, hashMapIteratorNode(t, it));
        assert(t, arrayBody(t, vtable, methodOffset(t, method)) == 0);
        set(t, vtable, ArrayBody + (methodOffset(t, method) * BytesPerWord),
            method);
        ++ i;
      }
    } else {
      if (superVirtualTable) {
        for (; i < arrayLength(t, superVirtualTable); ++i) {
          object method = arrayBody(t, superVirtualTable, i);
          method = hashMapFind(t, virtualMap, method, methodHash, methodEqual);

          set(t, vtable, ArrayBody + (i * BytesPerWord), method);
        }
      }

      for (object p = listFront(t, newVirtuals); p; p = pairSecond(t, p)) {
        set(t, vtable, ArrayBody + (i * BytesPerWord), pairFirst(t, p));
        ++ i;
      }
    }

    assert(t, arrayLength(t, vtable) == i);

    set(t, class_, ClassVirtualTable, vtable);

    if ((classFlags(t, class_) & ACC_INTERFACE) == 0) {
      // generate interface vtables
    
      object itable = classInterfaceTable(t, class_);
      if (itable) {
        PROTECT(t, itable);

        for (unsigned i = 0; i < arrayLength(t, itable); i += 2) {
          object ivtable = classVirtualTable(t, arrayBody(t, itable, i));
          if (ivtable) {
            object vtable = arrayBody(t, itable, i + 1);
        
            for (unsigned j = 0; j < arrayLength(t, ivtable); ++j) {
              object method = arrayBody(t, ivtable, j);
              method = hashMapFind
                (t, virtualMap, method, methodHash, methodEqual);
              assert(t, method);
              
              set(t, vtable, ArrayBody + (j * BytesPerWord), method);        
            }
          }
        }
      }
    }
  }
}

void
updateClassTables(Thread* t, object newClass, object oldClass)
{
  object fieldTable = classFieldTable(t, newClass);
  if (fieldTable) {
    for (unsigned i = 0; i < arrayLength(t, fieldTable); ++i) {
      set(t, arrayBody(t, fieldTable, i), FieldClass, newClass);
    }
  }

  if (classFlags(t, newClass) & ACC_INTERFACE) {
    object virtualTable = classVirtualTable(t, newClass);
    if (virtualTable) {
      for (unsigned i = 0; i < arrayLength(t, virtualTable); ++i) {
        if (methodClass(t, arrayBody(t, virtualTable, i)) == oldClass) {
          set(t, arrayBody(t, virtualTable, i), MethodClass, newClass);
        }
      }
    }
  } else {
    object methodTable = classMethodTable(t, newClass);
    if (methodTable) {
      for (unsigned i = 0; i < arrayLength(t, methodTable); ++i) {
        set(t, arrayBody(t, methodTable, i), MethodClass, newClass);
      }
    }
  }
}

void
updateBootstrapClass(Thread* t, object bootstrapClass, object class_)
{
  expect(t, bootstrapClass != class_);

  // verify that the classes have the same layout
  expect(t, classSuper(t, bootstrapClass) == classSuper(t, class_));

  expect(t, bootstrapClass == arrayBody(t, t->m->types, Machine::ClassType)
         or classFixedSize(t, bootstrapClass) == classFixedSize(t, class_));

  expect(t,
         (classVmFlags(t, bootstrapClass) & ReferenceFlag)
         or (classObjectMask(t, bootstrapClass) == 0
             and classObjectMask(t, class_) == 0)
         or intArrayEqual(t, classObjectMask(t, bootstrapClass),
                          classObjectMask(t, class_)));

  PROTECT(t, bootstrapClass);
  PROTECT(t, class_);

  ENTER(t, Thread::ExclusiveState);

  classVmFlags(t, bootstrapClass) &= ~BootstrapFlag;
  classVmFlags(t, bootstrapClass) |= classVmFlags(t, class_);
  classFlags(t, bootstrapClass) = classFlags(t, class_);

  set(t, bootstrapClass, ClassSuper, classSuper(t, class_));
  set(t, bootstrapClass, ClassInterfaceTable, classInterfaceTable(t, class_));
  set(t, bootstrapClass, ClassVirtualTable, classVirtualTable(t, class_));
  set(t, bootstrapClass, ClassFieldTable, classFieldTable(t, class_));
  set(t, bootstrapClass, ClassMethodTable, classMethodTable(t, class_));
  set(t, bootstrapClass, ClassStaticTable, classStaticTable(t, class_));

  updateClassTables(t, bootstrapClass, class_);
}

object
makeArrayClass(Thread* t, unsigned dimensions, object spec,
               object elementClass)
{
  // todo: arrays should implement Cloneable and Serializable
  object vtable = classVirtualTable
    (t, arrayBody(t, t->m->types, Machine::JobjectType));

  object c = t->m->processor->makeClass
    (t,
     0,
     0,
     dimensions,
     2 * BytesPerWord,
     BytesPerWord,
     classObjectMask(t, arrayBody(t, t->m->types, Machine::ArrayType)),
     spec,
     arrayBody(t, t->m->types, Machine::JobjectType),
     0,
     vtable,
     0,
     0,
     elementClass,
     t->m->loader,
     arrayLength(t, vtable));

  t->m->processor->initVtable(t, c);

  return c;
}

object
makeArrayClass(Thread* t, object spec)
{
  PROTECT(t, spec);

  const char* s = reinterpret_cast<const char*>(&byteArrayBody(t, spec, 0));
  const char* start = s;
  unsigned dimensions = 0;
  for (; *s == '['; ++s) ++ dimensions;

  object elementSpec;
  switch (*s) {
  case 'L': {
    ++ s;
    const char* elementSpecStart = s;
    while (*s and *s != ';') ++ s;
    
    elementSpec = makeByteArray(t, s - elementSpecStart + 1, false);
    memcpy(&byteArrayBody(t, elementSpec, 0),
           &byteArrayBody(t, spec, elementSpecStart - start),
           s - elementSpecStart);
    byteArrayBody(t, elementSpec, s - elementSpecStart) = 0;
  } break;

  default:
    if (dimensions > 1) {
      char c = *s;
      elementSpec = makeByteArray(t, 3, false);
      byteArrayBody(t, elementSpec, 0) = '[';
      byteArrayBody(t, elementSpec, 1) = c;
      byteArrayBody(t, elementSpec, 2) = 0;
      -- dimensions;
    } else {
      abort(t);
    }
  }

  object elementClass = hashMapFind
    (t, t->m->bootstrapClassMap, elementSpec, byteArrayHash, byteArrayEqual);

  if (elementClass == 0) {
    elementClass = resolveClass(t, elementSpec);
    if (UNLIKELY(t->exception)) return 0;
  }

  return makeArrayClass(t, dimensions, spec, elementClass);
}

void
removeMonitor(Thread* t, object o)
{
  object p = hashMapRemove(t, t->m->monitorMap, o, objectHash, objectEqual);

  assert(t, p);

  if (DebugMonitors) {
    fprintf(stderr, "dispose monitor %p for object %x\n",
            static_cast<System::Monitor*>(pointerValue(t, p)),
            objectHash(t, o));
  }

  static_cast<System::Monitor*>(pointerValue(t, p))->dispose();
}

void
removeString(Thread* t, object o)
{
  hashMapRemove(t, t->m->stringMap, o, stringHash, objectEqual);
}

void
invoke(Thread* t, const char* className, int argc, const char** argv)
{
  enter(t, Thread::ActiveState);

  object args = makeObjectArray
    (t, arrayBody(t, t->m->types, Machine::StringType), argc, true);

  PROTECT(t, args);

  for (int i = 0; i < argc; ++i) {
    object arg = makeString(t, "%s", argv[i]);
    set(t, args, ArrayBody + (i * BytesPerWord), arg);
  }

  t->m->processor->invoke
    (t, className, "main", "([Ljava/lang/String;)V", 0, args);
}

void
bootClass(Thread* t, Machine::Type type, int superType, uint32_t objectMask,
          unsigned fixedSize, unsigned arrayElementSize, unsigned vtableLength)
{
  object super = (superType >= 0 ? arrayBody(t, t->m->types, superType) : 0);

  object mask;
  if (objectMask) {
    if (super
        and classObjectMask(t, super)
        and intArrayBody(t, classObjectMask(t, super), 0)
        == static_cast<int32_t>(objectMask))
    {
      mask = classObjectMask(t, arrayBody(t, t->m->types, superType));
    } else {
      mask = makeIntArray(t, 1, false);
      intArrayBody(t, mask, 0) = objectMask;
    }
  } else {
    mask = 0;
  }

  super = (superType >= 0 ? arrayBody(t, t->m->types, superType) : 0);

  object class_ = t->m->processor->makeClass
    (t, 0, BootstrapFlag, 0, fixedSize, arrayElementSize, mask, 0, super, 0, 0,
     0, 0, 0, t->m->loader, vtableLength);

  set(t, t->m->types, ArrayBody + (type * BytesPerWord), class_);
}

void
bootJavaClass(Thread* t, Machine::Type type, int superType, const char* name,
              int vtableLength, object bootMethod)
{
  PROTECT(t, bootMethod);

  object n = makeByteArray(t, name);
  object class_ = arrayBody(t, t->m->types, type);

  set(t, class_, ClassName, n);

  object vtable;
  if (vtableLength >= 0) {
    PROTECT(t, class_);

    vtable = makeArray(t, vtableLength, false);
    for (int i = 0; i < vtableLength; ++ i) {
      arrayBody(t, vtable, i) = bootMethod;
    }
  } else {
    vtable = classVirtualTable(t, arrayBody(t, t->m->types, superType));
  }

  set(t, class_, ClassVirtualTable, vtable);

  t->m->processor->initVtable(t, class_);

  hashMapInsert(t, t->m->bootstrapClassMap, n, class_, byteArrayHash);
}

class HeapClient: public Heap::Client {
 public:
  HeapClient(Machine* m): m(m) { }

  virtual void visitRoots(Heap::Visitor* v) {
    v->visit(&(m->loader));
    v->visit(&(m->bootstrapClassMap));
    v->visit(&(m->monitorMap));
    v->visit(&(m->stringMap));
    v->visit(&(m->types));
    v->visit(&(m->jniInterfaceTable));

    for (Reference* r = m->jniReferences; r; r = r->next) {
      v->visit(&(r->target));
    }

    for (Thread* t = m->rootThread; t; t = t->peer) {
      ::visitRoots(t, v);
    }

    postVisit(m->rootThread, v);
  }

  virtual void collect(void* context, Heap::CollectionType type) {
    Thread* t = static_cast<Thread*>(context);
    ENTER(t, Thread::ExclusiveState);
    collect(t, type);
  }

  virtual bool isFixed(void* p) {
    return objectFixed(m->rootThread, static_cast<object>(p));
  }

  virtual unsigned sizeInWords(void* p) {
    Thread* t = m->rootThread;

    object o = static_cast<object>(m->heap->follow(mask(p)));

    unsigned n = baseSize(t, o, static_cast<object>
                          (m->heap->follow(objectClass(t, o))));

    if (objectExtended(t, o)) {
      ++ n;
    }

    return n;
  }

  virtual unsigned copiedSizeInWords(void* p) {
    Thread* t = m->rootThread;

    object o = static_cast<object>(m->heap->follow(mask(p)));
    assert(t, not objectFixed(t, o));

    unsigned n = baseSize(t, o, static_cast<object>
                          (m->heap->follow(objectClass(t, o))));

    if (objectExtended(t, o) or hashTaken(t, o)) {
      ++ n;
    }

    return n;
  }

  virtual void copy(void* srcp, void* dstp) {
    Thread* t = m->rootThread;

    object src = static_cast<object>(m->heap->follow(mask(srcp)));
    assert(t, not objectFixed(t, src));

    object class_ = static_cast<object>
      (m->heap->follow(objectClass(t, src)));

    unsigned base = baseSize(t, src, class_);
    unsigned n = extendedSize(t, src, base);

    object dst = static_cast<object>(dstp);

    memcpy(dst, src, n * BytesPerWord);

    if (hashTaken(t, src)) {
      cast<uintptr_t>(dst, 0) &= PointerMask;
      cast<uintptr_t>(dst, 0) |= ExtendedMark;
      extendedWord(t, dst, base) = takeHash(t, src);
    }
  }

  virtual void walk(void* p, Heap::Walker* w) {
    object o = static_cast<object>(m->heap->follow(mask(p)));
    ::walk(m->rootThread, w, o);
  }

  void dispose() {
    m->heap->free(this, sizeof(*this), false);
  }
    
 private:
  Machine* m;
};

} // namespace

namespace vm {

Machine::Machine(System* system, Heap* heap, Finder* finder,
                 Processor* processor):
  vtable(&javaVMVTable),
  system(system),
  heapClient(new (heap->allocate(sizeof(HeapClient), false))
             HeapClient(this)),
  heap(heap),
  finder(finder),
  processor(processor),
  rootThread(0),
  exclusive(0),
  jniReferences(0),
  builtins(0),
  activeCount(0),
  liveCount(0),
  fixedFootprint(0),
  localThread(0),
  stateLock(0),
  heapLock(0),
  classLock(0),
  referenceLock(0),
  libraries(0),
  loader(0),
  bootstrapClassMap(0),
  monitorMap(0),
  stringMap(0),
  types(0),
  jniInterfaceTable(0),
  finalizers(0),
  tenuredFinalizers(0),
  finalizeQueue(0),
  weakReferences(0),
  tenuredWeakReferences(0),
  unsafe(false),
  heapPoolIndex(0)
{
  heap->setClient(heapClient);

  populateJNITables(&javaVMVTable, &jniEnvVTable);

  if (not system->success(system->make(&localThread)) or
      not system->success(system->make(&stateLock)) or
      not system->success(system->make(&heapLock)) or
      not system->success(system->make(&classLock)) or
      not system->success(system->make(&referenceLock)) or
      not system->success(system->load(&libraries, 0, false, 0)))
  {
    system->abort();
  }
}

void
Machine::dispose()
{
  localThread->dispose();
  stateLock->dispose();
  heapLock->dispose();
  classLock->dispose();
  referenceLock->dispose();

  if (libraries) {
    libraries->dispose();
  }

  for (Reference* r = jniReferences; r;) {
    Reference* tmp = r;
    r = r->next;
    heap->free(tmp, sizeof(*tmp), false);
  }

  for (unsigned i = 0; i < heapPoolIndex; ++i) {
    heap->free(heapPool[i], Thread::HeapSizeInBytes, false);
  }

  static_cast<HeapClient*>(heapClient)->dispose();

  heap->free(this, sizeof(*this), false);
}

Thread::Thread(Machine* m, object javaThread, Thread* parent):
  vtable(&(m->jniEnvVTable)),
  m(m),
  parent(parent),
  peer((parent ? parent->child : 0)),
  child(0),
  state(NoState),
  criticalLevel(0),
  systemThread(0),
  javaThread(javaThread),
  exception(0),
  heapIndex(0),
  heapOffset(0),
  protector(0),
  runnable(this),
  defaultHeap(static_cast<uintptr_t*>
              (m->heap->allocate(HeapSizeInBytes, false))),
  heap(defaultHeap)
#ifdef VM_STRESS
  , stress(false)
#endif // VM_STRESS
{ }

void
Thread::init()
{
  if (parent == 0) {
    assert(this, m->rootThread == 0);
    assert(this, javaThread == 0);

    m->rootThread = this;
    m->unsafe = true;

    if (not m->system->success(m->system->attach(&runnable))) {
      abort(this);
    }

    Thread* t = this;

    t->m->loader = allocate(t, sizeof(void*) * 3, true);
    memset(t->m->loader, 0, sizeof(void*) * 2);

    t->m->types = allocate(t, pad((TypeCount + 2) * BytesPerWord), true);
    arrayLength(t, t->m->types) = TypeCount;
    memset(&arrayBody(t, t->m->types, 0), 0, TypeCount * BytesPerWord);

#include "type-initializations.cpp"

    object arrayClass = arrayBody(t, t->m->types, Machine::ArrayType);
    set(t, t->m->types, 0, arrayClass);

    object loaderClass = arrayBody
      (t, t->m->types, Machine::SystemClassLoaderType);
    set(t, t->m->loader, 0, loaderClass);

    object objectClass = arrayBody(t, m->types, Machine::JobjectType);

    object classClass = arrayBody(t, m->types, Machine::ClassType);
    set(t, classClass, 0, classClass);
    set(t, classClass, ClassSuper, objectClass);

    object intArrayClass = arrayBody(t, m->types, Machine::IntArrayType);
    set(t, intArrayClass, 0, classClass);
    set(t, intArrayClass, ClassSuper, objectClass);

    m->unsafe = false;

    classVmFlags(t, arrayBody(t, m->types, Machine::SingletonType))
      |= SingletonFlag;

    classVmFlags(t, arrayBody(t, m->types, Machine::JreferenceType))
      |= ReferenceFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::WeakReferenceType))
      |= ReferenceFlag | WeakReferenceFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::PhantomReferenceType))
      |= ReferenceFlag | WeakReferenceFlag;

    classVmFlags(t, arrayBody(t, m->types, Machine::JbooleanType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JbyteType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JcharType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JshortType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JintType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JlongType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JfloatType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JdoubleType))
      |= PrimitiveFlag;
    classVmFlags(t, arrayBody(t, m->types, Machine::JvoidType))
      |= PrimitiveFlag;

    m->bootstrapClassMap = makeHashMap(this, 0, 0);

    { object loaderMap = makeHashMap(this, 0, 0);
      set(t, m->loader, SystemClassLoaderMap, loaderMap);
    }

    m->monitorMap = makeWeakHashMap(this, 0, 0);
    m->stringMap = makeWeakHashMap(this, 0, 0);

    m->jniInterfaceTable = makeVector(this, 0, 0, false);

    m->localThread->set(this);

    { object bootCode = makeCode(t, 0, 0, 0, 0, 0, 1, false);
      codeBody(t, bootCode, 0) = impdep1;
      object bootMethod = makeMethod
        (t, 0, 0, 0, 0, 0, 0, 0, 0, 0, bootCode, 0);
      PROTECT(t, bootMethod);

#include "type-java-initializations.cpp"
    }
  } else {
    peer = parent->child;
    parent->child = this;
  }

  if (javaThread) {
    threadPeer(this, javaThread) = reinterpret_cast<jlong>(this);
  } else {
    this->javaThread = makeThread
      (this, reinterpret_cast<int64_t>(this), 0, 0, 0, 0, m->loader);
  }
}

void
Thread::exit()
{
  if (state != Thread::ExitState and
      state != Thread::ZombieState)
  {
    enter(this, Thread::ExclusiveState);

    if (m->liveCount == 1) {
      vm::exit(this);
    } else {
      enter(this, Thread::ZombieState);
    }
  }
}

void
Thread::dispose()
{
  if (systemThread) {
    systemThread->dispose();
  }

  m->heap->free(defaultHeap, Thread::HeapSizeInBytes, false);

  m->processor->dispose(this);
}

void
exit(Thread* t)
{
  enter(t, Thread::ExitState);

  joinAll(t, t->m->rootThread);

  for (object* p = &(t->m->finalizers); *p;) {
    object f = *p;
    *p = finalizerNext(t, *p);

    void (*function)(Thread*, object);
    memcpy(&function, &finalizerFinalize(t, f), BytesPerWord);
    function(t, finalizerTarget(t, f));
  }

  for (object* p = &(t->m->tenuredFinalizers); *p;) {
    object f = *p;
    *p = finalizerNext(t, *p);

    void (*function)(Thread*, object);
    memcpy(&function, &finalizerFinalize(t, f), BytesPerWord);
    function(t, finalizerTarget(t, f));
  }

  disposeAll(t, t->m->rootThread);
}

void
enter(Thread* t, Thread::State s)
{
  stress(t);

  if (s == t->state) return;

  if (t->state == Thread::ExitState) {
    // once in exit state, we stay that way
    return;
  }

  ACQUIRE_RAW(t, t->m->stateLock);

  switch (s) {
  case Thread::ExclusiveState: {
    assert(t, t->state == Thread::ActiveState);

    while (t->m->exclusive) {
      // another thread got here first.
      ENTER(t, Thread::IdleState);
    }

    t->state = Thread::ExclusiveState;
    t->m->exclusive = t;
      
    while (t->m->activeCount > 1) {
      t->m->stateLock->wait(t->systemThread, 0);
    }
  } break;

  case Thread::IdleState:
  case Thread::ZombieState: {
    switch (t->state) {
    case Thread::ExclusiveState: {
      assert(t, t->m->exclusive == t);
      t->m->exclusive = 0;
    } break;

    case Thread::ActiveState: break;

    default: abort(t);
    }

    assert(t, t->m->activeCount > 0);
    -- t->m->activeCount;

    if (s == Thread::ZombieState) {
      assert(t, t->m->liveCount > 0);
      -- t->m->liveCount;
    }
    t->state = s;

    t->m->stateLock->notifyAll(t->systemThread);
  } break;

  case Thread::ActiveState: {
    switch (t->state) {
    case Thread::ExclusiveState: {
      assert(t, t->m->exclusive == t);

      t->state = s;
      t->m->exclusive = 0;

      t->m->stateLock->notifyAll(t->systemThread);
    } break;

    case Thread::NoState:
    case Thread::IdleState: {
      while (t->m->exclusive) {
        t->m->stateLock->wait(t->systemThread, 0);
      }

      ++ t->m->activeCount;
      if (t->state == Thread::NoState) {
        ++ t->m->liveCount;
      }
      t->state = s;
    } break;

    default: abort(t);
    }
  } break;

  case Thread::ExitState: {
    switch (t->state) {
    case Thread::ExclusiveState: {
      assert(t, t->m->exclusive == t);
      t->m->exclusive = 0;

      t->m->stateLock->notifyAll(t->systemThread);
    } break;

    case Thread::ActiveState: break;

    default: abort(t);
    }

    assert(t, t->m->activeCount > 0);
    -- t->m->activeCount;

    t->state = s;

    while (t->m->liveCount > 1) {
      t->m->stateLock->wait(t->systemThread, 0);
    }
  } break;

  default: abort(t);
  }
}

object
allocate2(Thread* t, unsigned sizeInBytes, bool objectMask)
{
  return allocate3
    (t, t->m->heap,
     ceiling(sizeInBytes, BytesPerWord) > Thread::HeapSizeInWords ?
     Machine::FixedAllocation : Machine::MovableAllocation,
     sizeInBytes, false, objectMask);
}

object
allocate3(Thread* t, Allocator* allocator, Machine::AllocationType type,
          unsigned sizeInBytes, bool executable, bool objectMask)
{
  ACQUIRE_RAW(t, t->m->stateLock);

  while (t->m->exclusive and t->m->exclusive != t) {
    // another thread wants to enter the exclusive state, either for a
    // collection or some other reason.  We give it a chance here.
    ENTER(t, Thread::IdleState);
  }

  if (type == Machine::FixedAllocation) {
    if (t->m->fixedFootprint + sizeInBytes
        > Machine::FixedFootprintThresholdInBytes)
    {
      t->heap = 0;
    }
  } else if (t->heapIndex + ceiling(sizeInBytes, BytesPerWord)
             >= Thread::HeapSizeInWords)
  {
    t->heap = 0;
    if (t->m->heapPoolIndex < Machine::HeapPoolSize) {
      t->heap = static_cast<uintptr_t*>
        (t->m->heap->tryAllocate(Thread::HeapSizeInBytes, false));
      if (t->heap) {
        t->m->heapPool[t->m->heapPoolIndex++] = t->heap;
        t->heapOffset += t->heapIndex;
        t->heapIndex = 0;
      }
    }
  }

  if (t->heap == 0) {
    ENTER(t, Thread::ExclusiveState);
    collect(t, Heap::MinorCollection);
  }
  
  switch (type) {
  case Machine::MovableAllocation: {
    return allocateSmall(t, sizeInBytes);
  }

  case Machine::FixedAllocation: {
    unsigned total;
    object o = static_cast<object>
      (t->m->heap->allocateFixed
       (allocator, ceiling(sizeInBytes, BytesPerWord), objectMask, &total));

    cast<uintptr_t>(o, 0) = FixedMark;

    t->m->fixedFootprint += total;

    return o;
  }

  case Machine::ImmortalAllocation: {
    unsigned total;
    object o = static_cast<object>
      (t->m->heap->allocateImmortal
       (allocator, ceiling(sizeInBytes, BytesPerWord),
        executable, objectMask, &total));

    cast<uintptr_t>(o, 0) = FixedMark;

    return o;
  }

  default: abort(t);
  }
}

object
makeByteArray(Thread* t, const char* format, ...)
{
  va_list a;
  va_start(a, format);
  object s = ::makeByteArray(t, format, a);
  va_end(a);

  return s;
}

object
makeString(Thread* t, const char* format, ...)
{
  va_list a;
  va_start(a, format);
  object s = ::makeByteArray(t, format, a);
  va_end(a);

  return makeString(t, s, 0, byteArrayLength(t, s) - 1, 0);
}

void
stringChars(Thread* t, object string, char* chars)
{
  object data = stringData(t, string);
  if (objectClass(t, data)
      == arrayBody(t, t->m->types, Machine::ByteArrayType))
  {
    memcpy(chars,
           &byteArrayBody(t, data, stringOffset(t, string)),
           stringLength(t, string));
  } else {
    for (unsigned i = 0; i < stringLength(t, string); ++i) {
      chars[i] = charArrayBody(t, data, stringOffset(t, string) + i);
    }
  }
  chars[stringLength(t, string)] = 0;
}

bool
isAssignableFrom(Thread* t, object a, object b)
{
  if (a == b) return true;

  if (classFlags(t, a) & ACC_INTERFACE) {
    if (classVmFlags(t, b) & BootstrapFlag) {
      resolveClass(t, className(t, b));
      if (UNLIKELY(t->exception)) {
        t->exception = 0;
        return false;
      }
    }

    for (; b; b = classSuper(t, b)) {
      object itable = classInterfaceTable(t, b);
      if (itable) {
        for (unsigned i = 0; i < arrayLength(t, itable); i += 2) {
          if (arrayBody(t, itable, i) == a) {
            return true;
          }
        }
      }
    }
  } else if (classArrayDimensions(t, a)) {
    if (classArrayDimensions(t, b)) {
      return isAssignableFrom
        (t, classStaticTable(t, a), classStaticTable(t, b));
    }
  } else {
    for (; b; b = classSuper(t, b)) {
      if (b == a) {
        return true;
      }
    }
  }

  return false;
}

bool
instanceOf(Thread* t, object class_, object o)
{
  if (o == 0) {
    return false;
  } else {
    return isAssignableFrom(t, class_, objectClass(t, o));
  }
}

object
classInitializer(Thread* t, object class_)
{
  for (unsigned i = 0; i < arrayLength(t, classMethodTable(t, class_)); ++i) {
    object o = arrayBody(t, classMethodTable(t, class_), i);

    if (strcmp(reinterpret_cast<const int8_t*>("<clinit>"),
               &byteArrayBody(t, methodName(t, o), 0)) == 0)
    {
      return o;
    }               
  }
  abort(t);
}

unsigned
fieldCode(Thread* t, unsigned javaCode)
{
  switch (javaCode) {
  case 'B':
    return ByteField;
  case 'C':
    return CharField;
  case 'D':
    return DoubleField;
  case 'F':
    return FloatField;
  case 'I':
    return IntField;
  case 'J':
    return LongField;
  case 'S':
    return ShortField;
  case 'V':
    return VoidField;
  case 'Z':
    return BooleanField;
  case 'L':
  case '[':
    return ObjectField;

  default: abort(t);
  }
}

unsigned
fieldType(Thread* t, unsigned code)
{
  switch (code) {
  case VoidField:
    return VOID_TYPE;
  case ByteField:
  case BooleanField:
    return INT8_TYPE;
  case CharField:
  case ShortField:
    return INT16_TYPE;
  case DoubleField:
    return DOUBLE_TYPE;
  case FloatField:
    return FLOAT_TYPE;
  case IntField:
    return INT32_TYPE;
  case LongField:
    return INT64_TYPE;
  case ObjectField:
    return POINTER_TYPE;

  default: abort(t);
  }
}

unsigned
primitiveSize(Thread* t, unsigned code)
{
  switch (code) {
  case VoidField:
    return 0;
  case ByteField:
  case BooleanField:
    return 1;
  case CharField:
  case ShortField:
    return 2;
  case FloatField:
  case IntField:
    return 4;
  case DoubleField:
  case LongField:
    return 8;

  default: abort(t);
  }
}

object
findLoadedClass(Thread* t, object spec)
{
  PROTECT(t, spec);
  ACQUIRE(t, t->m->classLock);

  return hashMapFind(t, systemClassLoaderMap(t, t->m->loader),
                     spec, byteArrayHash, byteArrayEqual);
}

object
parseClass(Thread* t, const uint8_t* data, unsigned size)
{
  class Client : public Stream::Client {
   public:
    Client(Thread* t): t(t) { }

    virtual void NO_RETURN handleError() {
      abort(t);
    }

   private:
    Thread* t;
  } client(t);

  Stream s(&client, data, size);

  uint32_t magic = s.read4();
  expect(t, magic == 0xCAFEBABE);
  s.read2(); // minor version
  s.read2(); // major version

  object pool = parsePool(t, s);
  PROTECT(t, pool);

  unsigned flags = s.read2();
  unsigned name = s.read2();

  object class_ = makeClass(t,
                            flags,
                            0, // VM flags
                            0, // array dimensions
                            0, // fixed size
                            0, // array size
                            0, // object mask
                            singletonObject(t, pool, name - 1),
                            0, // super
                            0, // interfaces
                            0, // vtable
                            0, // fields
                            0, // methods
                            0, // static table
                            t->m->loader,
                            0, // vtable length
                            false);
  PROTECT(t, class_);
  
  unsigned super = s.read2();
  if (super) {
    object sc = resolveClass(t, singletonObject(t, pool, super - 1));
    if (UNLIKELY(t->exception)) return 0;

    set(t, class_, ClassSuper, sc);

    classVmFlags(t, class_)
      |= (classVmFlags(t, sc) & (ReferenceFlag | WeakReferenceFlag));
  }
  
  parseInterfaceTable(t, s, class_, pool);
  if (UNLIKELY(t->exception)) return 0;

  parseFieldTable(t, s, class_, pool);
  if (UNLIKELY(t->exception)) return 0;

  parseMethodTable(t, s, class_, pool);
  if (UNLIKELY(t->exception)) return 0;

  object vtable = classVirtualTable(t, class_);
  unsigned vtableLength = (vtable ? arrayLength(t, vtable) : 0);

  object real = t->m->processor->makeClass
    (t,
     classFlags(t, class_),
     classVmFlags(t, class_),
     classArrayDimensions(t, class_),
     classFixedSize(t, class_),
     classArrayElementSize(t, class_),
     classObjectMask(t, class_),
     className(t, class_),
     classSuper(t, class_),
     classInterfaceTable(t, class_),
     classVirtualTable(t, class_),
     classFieldTable(t, class_),
     classMethodTable(t, class_),
     classStaticTable(t, class_),
     classLoader(t, class_),
     vtableLength);

  t->m->processor->initVtable(t, real);

  updateClassTables(t, real, class_);

  return real;
}

object
resolveClass(Thread* t, object spec)
{
  PROTECT(t, spec);
  ACQUIRE(t, t->m->classLock);

  object class_ = hashMapFind(t, systemClassLoaderMap(t, t->m->loader),
                              spec, byteArrayHash, byteArrayEqual);
  if (class_ == 0) {
    if (byteArrayBody(t, spec, 0) == '[') {
      class_ = hashMapFind
        (t, t->m->bootstrapClassMap, spec, byteArrayHash, byteArrayEqual);

      if (class_) {
        set(t, class_, ClassVirtualTable,
            classVirtualTable
            (t, arrayBody(t, t->m->types, Machine::JobjectType)));
      } else {
        class_ = makeArrayClass(t, spec);
      }
    } else {
      char file[byteArrayLength(t, spec) + 6];
      memcpy(file, &byteArrayBody(t, spec, 0), byteArrayLength(t, spec) - 1);
      memcpy(file + byteArrayLength(t, spec) - 1, ".class", 7);

      System::Region* region = t->m->finder->find(file);

      if (region) {
        if (Verbose) {
          fprintf(stderr, "parsing %s\n", &byteArrayBody(t, spec, 0));
        }

        // parse class file
        class_ = parseClass(t, region->start(), region->length());
        region->dispose();

        if (LIKELY(t->exception == 0)) {
          if (Verbose) {
            fprintf(stderr, "done parsing %s: %p\n",
                    &byteArrayBody(t, spec, 0),
                    class_);
          }

          object bootstrapClass = hashMapFind
            (t, t->m->bootstrapClassMap, spec, byteArrayHash, byteArrayEqual);

          if (bootstrapClass) {
            PROTECT(t, bootstrapClass);

            updateBootstrapClass(t, bootstrapClass, class_);
            class_ = bootstrapClass;
          }
        }
      }
    }

    if (class_) {
      PROTECT(t, class_);

      hashMapInsert(t, systemClassLoaderMap(t, t->m->loader),
                    spec, class_, byteArrayHash);
    } else if (t->exception == 0) {
      object message = makeString(t, "%s", &byteArrayBody(t, spec, 0));
      t->exception = makeClassNotFoundException(t, message);
    }
  }

  return class_;
}

object
resolveMethod(Thread* t, const char* className, const char* methodName,
              const char* methodSpec)
{
  object class_ = resolveClass(t, makeByteArray(t, "%s", className));
  if (LIKELY(t->exception == 0)) {
    PROTECT(t, class_);

    object name = makeByteArray(t, methodName);
    PROTECT(t, name);

    object spec = makeByteArray(t, methodSpec);
    object reference = makeReference(t, class_, name, spec);
    
    return findMethodInClass(t, class_, referenceName(t, reference),
                             referenceSpec(t, reference));
  }

  return 0;
}

object
resolveObjectArrayClass(Thread* t, object elementSpec)
{
  PROTECT(t, elementSpec);

  object spec;
  if (byteArrayBody(t, elementSpec, 0) == '[') {
    spec = makeByteArray(t, byteArrayLength(t, elementSpec) + 1, false);
    byteArrayBody(t, spec, 0) = '[';
    memcpy(&byteArrayBody(t, spec, 1),
           &byteArrayBody(t, elementSpec, 0),
           byteArrayLength(t, elementSpec));
  } else {
    spec = makeByteArray(t, byteArrayLength(t, elementSpec) + 3, false);
    byteArrayBody(t, spec, 0) = '[';
    byteArrayBody(t, spec, 1) = 'L';
    memcpy(&byteArrayBody(t, spec, 2),
           &byteArrayBody(t, elementSpec, 0),
           byteArrayLength(t, elementSpec) - 1);
    byteArrayBody(t, spec, byteArrayLength(t, elementSpec) + 1) = ';';
    byteArrayBody(t, spec, byteArrayLength(t, elementSpec) + 2) = 0;
  }

  return resolveClass(t, spec);
}

object
makeObjectArray(Thread* t, object elementClass, unsigned count, bool clear)
{
  object arrayClass = resolveObjectArrayClass(t, className(t, elementClass));
  PROTECT(t, arrayClass);

  object array = makeArray(t, count, clear);
  setObjectClass(t, array, arrayClass);

  return array;
}

object
findInTable(Thread* t, object table, object name, object spec,
            object& (*getName)(Thread*, object),
            object& (*getSpec)(Thread*, object))
{
  if (table) {
    for (unsigned i = 0; i < arrayLength(t, table); ++i) {
      object o = arrayBody(t, table, i);      
      if (strcmp(&byteArrayBody(t, getName(t, o), 0),
                 &byteArrayBody(t, name, 0)) == 0 and
          strcmp(&byteArrayBody(t, getSpec(t, o), 0),
                 &byteArrayBody(t, spec, 0)) == 0)
      {
        return o;
      }
    }
  }

  return 0;
}

object
findInHierarchy(Thread* t, object class_, object name, object spec,
                object (*find)(Thread*, object, object, object),
                object (*makeError)(Thread*, object))
{
  object originalClass = class_;
  PROTECT(t, class_);

  object o = 0;
  if (classFlags(t, class_) & ACC_INTERFACE) {
    if (classVirtualTable(t, class_)) {
      o = findInTable
        (t, classVirtualTable(t, class_), name, spec, methodName, methodSpec);
    }
  } else {
    for (; o == 0 and class_; class_ = classSuper(t, class_)) {
      o = find(t, class_, name, spec);
    }
  }

  if (o == 0) {
    object message = makeString
      (t, "%s %s not found in %s",
       &byteArrayBody(t, name, 0),
       &byteArrayBody(t, spec, 0),
       &byteArrayBody(t, className(t, originalClass), 0));
    t->exception = makeError(t, message);
  }

  return o;
}

unsigned
parameterFootprint(Thread* t, const char* s, bool static_)
{
  unsigned footprint = 0;
  for (MethodSpecIterator it(t, s); it.hasNext();) {
    switch (*it.next()) {
    case 'J':
    case 'D':
      footprint += 2;
      break;

    default:
      ++ footprint;
      break;        
    }
  }

  if (not static_) {
    ++ footprint;
  }
  return footprint;
}

void
addFinalizer(Thread* t, object target, void (*finalize)(Thread*, object))
{
  PROTECT(t, target);

  ACQUIRE(t, t->m->referenceLock);

  void* function;
  memcpy(&function, &finalize, BytesPerWord);

  object f = makeFinalizer(t, 0, function, 0);
  finalizerTarget(t, f) = target;
  finalizerNext(t, f) = t->m->finalizers;
  t->m->finalizers = f;
}

System::Monitor*
objectMonitor(Thread* t, object o, bool createNew)
{
  object p = hashMapFind(t, t->m->monitorMap, o, objectHash, objectEqual);

  if (p) {
    if (DebugMonitors) {
      fprintf(stderr, "found monitor %p for object %x\n",
              static_cast<System::Monitor*>(pointerValue(t, p)),
              objectHash(t, o));
    }

    return static_cast<System::Monitor*>(pointerValue(t, p));
  } else if (createNew) {
    PROTECT(t, o);

    ENTER(t, Thread::ExclusiveState);

    p = hashMapFind(t, t->m->monitorMap, o, objectHash, objectEqual);
    if (p) {
      if (DebugMonitors) {
        fprintf(stderr, "found monitor %p for object %x\n",
                static_cast<System::Monitor*>(pointerValue(t, p)),
                objectHash(t, o));
      }

      return static_cast<System::Monitor*>(pointerValue(t, p));
    }

    System::Monitor* m;
    System::Status s = t->m->system->make(&m);
    expect(t, t->m->system->success(s));

    if (DebugMonitors) {
      fprintf(stderr, "made monitor %p for object %x\n",
              m,
              objectHash(t, o));
    }

    p = makePointer(t, m);
    hashMapInsert(t, t->m->monitorMap, o, p, objectHash);

    addFinalizer(t, o, removeMonitor);

    return m;
  } else {
    return 0;
  }
}

object
intern(Thread* t, object s)
{
  PROTECT(t, s);

  ACQUIRE(t, t->m->referenceLock);

  object n = hashMapFindNode(t, t->m->stringMap, s, stringHash, stringEqual);
  if (n) {
    return jreferenceTarget(t, tripleFirst(t, n));
  } else {
    hashMapInsert(t, t->m->stringMap, s, 0, stringHash);
    addFinalizer(t, s, removeString);
    return s;
  }
}

void
collect(Thread* t, Heap::CollectionType type)
{
#ifdef VM_STRESS
  bool stress = t->stress;
  if (not stress) t->stress = true;
#endif

  Machine* m = t->m;

  m->unsafe = true;
  m->heap->collect(type, footprint(m->rootThread));
  m->unsafe = false;

  postCollect(m->rootThread);

  for (object f = m->finalizeQueue; f; f = finalizerNext(t, f)) {
    void (*function)(Thread*, object);
    memcpy(&function, &finalizerFinalize(t, f), BytesPerWord);
    function(t, finalizerTarget(t, f));
  }
  m->finalizeQueue = 0;

  killZombies(t, m->rootThread);

  for (unsigned i = 0; i < m->heapPoolIndex; ++i) {
    m->heap->free(m->heapPool[i], Thread::HeapSizeInBytes, false);
  }
  m->heapPoolIndex = 0;

  m->fixedFootprint = 0;

#ifdef VM_STRESS
  if (not stress) t->stress = false;
#endif
}

void
printTrace(Thread* t, object exception)
{
  if (exception == 0) {
    exception = makeNullPointerException(t, 0, makeTrace(t), 0);
  }

  for (object e = exception; e; e = throwableCause(t, e)) {
    if (e != exception) {
      fprintf(stderr, "caused by: ");
    }

    fprintf(stderr, "%s", &byteArrayBody
            (t, className(t, objectClass(t, e)), 0));
  
    if (throwableMessage(t, e)) {
      object m = throwableMessage(t, e);
      char message[stringLength(t, m) + 1];
      stringChars(t, m, message);
      fprintf(stderr, ": %s\n", message);
    } else {
      fprintf(stderr, "\n");
    }

    object trace = throwableTrace(t, e);
    for (unsigned i = 0; i < arrayLength(t, trace); ++i) {
      object e = arrayBody(t, trace, i);
      const int8_t* class_ = &byteArrayBody
        (t, className(t, methodClass(t, traceElementMethod(t, e))), 0);
      const int8_t* method = &byteArrayBody
        (t, methodName(t, traceElementMethod(t, e)), 0);
      int line = t->m->processor->lineNumber
        (t, traceElementMethod(t, e), traceElementIp(t, e));

      fprintf(stderr, "  at %s.%s ", class_, method);

      switch (line) {
      case NativeLine:
        fprintf(stderr, "(native)\n");
        break;
      case UnknownLine:
        fprintf(stderr, "(unknown line)\n");
        break;
      default:
        fprintf(stderr, "(line %d)\n", line);
      }
    }
  }
}

object
makeTrace(Thread* t, Processor::StackWalker* walker)
{
  class Visitor: public Processor::StackVisitor {
   public:
    Visitor(Thread* t): t(t), trace(0), index(0), protector(t, &trace) { }

    virtual bool visit(Processor::StackWalker* walker) {
      if (trace == 0) {
        trace = makeArray(t, walker->count(), true);
      }

      object e = makeTraceElement(t, walker->method(), walker->ip());
      set(t, trace, ArrayBody + (index * BytesPerWord), e);
      ++ index;
      return true;
    }

    Thread* t;
    object trace;
    unsigned index;
    Thread::SingleProtector protector;
  } v(t);

  walker->walk(&v);

  return v.trace ? v.trace : makeArray(t, 0, true);
}

object
makeTrace(Thread* t)
{
  class Visitor: public Processor::StackVisitor {
   public:
    Visitor(Thread* t): t(t), trace(0) { }

    virtual bool visit(Processor::StackWalker* walker) {
      trace = makeTrace(t, walker);
      return false;
    }

    Thread* t;
    object trace;
  } v(t);

  t->m->processor->walkStack(t, &v);

  return v.trace ? v.trace : makeArray(t, 0, true);
}

void
noop()
{ }

#include "type-constructors.cpp"

} // namespace vm

// for debugging
void
vmPrintTrace(Thread* t)
{
  class Visitor: public Processor::StackVisitor {
   public:
    Visitor(Thread* t): t(t) { }

    virtual bool visit(Processor::StackWalker* walker) {
      const int8_t* class_ = &byteArrayBody
        (t, className(t, methodClass(t, walker->method())), 0);
      const int8_t* method = &byteArrayBody
        (t, methodName(t, walker->method()), 0);
      int line = t->m->processor->lineNumber
        (t, walker->method(), walker->ip());

      fprintf(stderr, "  at %s.%s ", class_, method);

      switch (line) {
      case NativeLine:
        fprintf(stderr, "(native)\n");
        break;
      case UnknownLine:
        fprintf(stderr, "(unknown line)\n");
        break;
      default:
        fprintf(stderr, "(line %d)\n", line);
      }

      return true;
    }

    Thread* t;
  } v(t);

  t->m->processor->walkStack(t, &v);
}