natclass.cc

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  for (; klass; klass = klass->getSuperclass())
    {
      _Jv_Method *meth = _Jv_GetMethodLocal (klass, name, signature);

      if (meth)
        return meth;
    }

  return NULL;
}

// NOTE: MCACHE_SIZE should be a power of 2 minus one.
#define MCACHE_SIZE 1023

struct _Jv_mcache
{
  jclass klass;
  _Jv_Method *method;
};

static _Jv_mcache method_cache[MCACHE_SIZE + 1];

static void *
_Jv_FindMethodInCache (jclass klass,
                       _Jv_Utf8Const *name,
                       _Jv_Utf8Const *signature)
{
  int index = name->hash & MCACHE_SIZE;
  _Jv_mcache *mc = method_cache + index;
  _Jv_Method *m = mc->method;

  if (mc->klass == klass
      && m != NULL             // thread safe check
      && _Jv_equalUtf8Consts (m->name, name)
      && _Jv_equalUtf8Consts (m->signature, signature))
    return mc->method->ncode;
  return NULL;
}

static void
_Jv_AddMethodToCache (jclass klass,
                       _Jv_Method *method)
{
  _Jv_MonitorEnter (&java::lang::Class::class$); 

  int index = method->name->hash & MCACHE_SIZE;

  method_cache[index].method = method;
  method_cache[index].klass = klass;

  _Jv_MonitorExit (&java::lang::Class::class$);
}

void *
_Jv_LookupInterfaceMethod (jclass klass, _Jv_Utf8Const *name,
                           _Jv_Utf8Const *signature)
{
  using namespace java::lang::reflect;

  void *ncode = _Jv_FindMethodInCache (klass, name, signature);
  if (ncode != 0)
    return ncode;

  for (; klass; klass = klass->getSuperclass())
    {
      _Jv_Method *meth = _Jv_GetMethodLocal (klass, name, signature);
      if (! meth)
        continue;

      if (Modifier::isStatic(meth->accflags))
	throw new java::lang::IncompatibleClassChangeError
	  (_Jv_GetMethodString (klass, meth->name));
      if (Modifier::isAbstract(meth->accflags))
	throw new java::lang::AbstractMethodError
	  (_Jv_GetMethodString (klass, meth->name));
      if (! Modifier::isPublic(meth->accflags))
	throw new java::lang::IllegalAccessError
	  (_Jv_GetMethodString (klass, meth->name));

      _Jv_AddMethodToCache (klass, meth);

      return meth->ncode;
    }
  throw new java::lang::IncompatibleClassChangeError;
}

// Fast interface method lookup by index.
void *
_Jv_LookupInterfaceMethodIdx (jclass klass, jclass iface, int method_idx)
{
  _Jv_IDispatchTable *cldt = klass->idt;
  int idx = iface->idt->iface.ioffsets[cldt->cls.iindex] + method_idx;
  return cldt->cls.itable[idx];
}

jboolean
_Jv_IsAssignableFrom (jclass target, jclass source)
{
  if (source == target)
    return true;

  // If target is array, so must source be.  
  while (target->isArray ())
    {
      if (! source->isArray())
	return false;
      target = target->getComponentType();
      source = source->getComponentType();
    }

  if (target->isInterface())
    {
      // Abstract classes have no IDT, and IDTs provide no way to check
      // two interfaces for assignability.
      if (__builtin_expect 
          (source->idt == NULL || source->isInterface(), false))
        return _Jv_InterfaceAssignableFrom (target, source);

      _Jv_IDispatchTable *cl_idt = source->idt;
      _Jv_IDispatchTable *if_idt = target->idt;

      if (__builtin_expect ((if_idt == NULL), false))
	return false; // No class implementing TARGET has been loaded.    
      jshort cl_iindex = cl_idt->cls.iindex;
      if (cl_iindex < if_idt->iface.ioffsets[0])
        {
	  jshort offset = if_idt->iface.ioffsets[cl_iindex];
	  if (offset != -1 && offset < cl_idt->cls.itable_length
	      && cl_idt->cls.itable[offset] == target)
	    return true;
	}
      return false;
    }

  // Primitive TYPE classes are only assignable to themselves.
  if (__builtin_expect (target->isPrimitive() || source->isPrimitive(), false))
    return false;

  if (target == &java::lang::Object::class$)
    return true;
  else if (source->ancestors == NULL || target->ancestors == NULL)
    {
      // We need this case when either SOURCE or TARGET has not has
      // its constant-time tables prepared.

      // At this point we know that TARGET can't be Object, so it is
      // safe to use that as the termination point.
      while (source && source != &java::lang::Object::class$)
	{
	  if (source == target)
	    return true;
	  source = source->getSuperclass();
	}
    }
  else if (source->depth >= target->depth
	   && source->ancestors[source->depth - target->depth] == target)
    return true;

  return false;
}

// Interface type checking, the slow way. Returns TRUE if IFACE is a 
// superinterface of SOURCE. This is used when SOURCE is also an interface,
// or a class with no interface dispatch table.
jboolean
_Jv_InterfaceAssignableFrom (jclass iface, jclass source)
{
  for (int i = 0; i < source->interface_count; i++)
    {
      jclass interface = source->interfaces[i];
      if (iface == interface
          || _Jv_InterfaceAssignableFrom (iface, interface))
        return true;      
    }
    
  if (!source->isInterface()
      && source->superclass 
      && _Jv_InterfaceAssignableFrom (iface, source->superclass))
    return true;
        
  return false;
}

jboolean
_Jv_IsInstanceOf(jobject obj, jclass cl)
{
  if (__builtin_expect (!obj, false))
    return false;
  return (_Jv_IsAssignableFrom (cl, JV_CLASS (obj)));
}

void *
_Jv_CheckCast (jclass c, jobject obj)
{
  if (__builtin_expect 
       (obj != NULL && ! _Jv_IsAssignableFrom(c, JV_CLASS (obj)), false))
    throw new java::lang::ClassCastException
      ((new java::lang::StringBuffer
	(obj->getClass()->getName()))->append
       (JvNewStringUTF(" cannot be cast to "))->append
       (c->getName())->toString());

  return obj;
}

void
_Jv_CheckArrayStore (jobject arr, jobject obj)
{
  if (obj)
    {
      JvAssert (arr != NULL);
      jclass elt_class = (JV_CLASS (arr))->getComponentType();
      if (elt_class == &java::lang::Object::class$)
	return;
      jclass obj_class = JV_CLASS (obj);
      if (__builtin_expect 
          (! _Jv_IsAssignableFrom (elt_class, obj_class), false))
	throw new java::lang::ArrayStoreException
		((new java::lang::StringBuffer
		 (JvNewStringUTF("Cannot store ")))->append
		 (obj_class->getName())->append
		 (JvNewStringUTF(" in array of type "))->append
		 (elt_class->getName())->toString());
    }
}

#define INITIAL_IOFFSETS_LEN 4
#define INITIAL_IFACES_LEN 4

static _Jv_IDispatchTable null_idt = { {SHRT_MAX, 0, NULL} };

// Generate tables for constant-time assignment testing and interface
// method lookup. This implements the technique described by Per Bothner
// <[e-mail]> on the java-discuss mailing list on 1999-09-02:
// http://gcc.gnu.org/ml/java/1999-q3/msg00377.html
void 
_Jv_PrepareConstantTimeTables (jclass klass)
{  
  if (klass->isPrimitive () || klass->isInterface ())
    return;
  
  // Short-circuit in case we've been called already.
  if ((klass->idt != NULL) || klass->depth != 0)
    return;

  // Calculate the class depth and ancestor table. The depth of a class 
  // is how many "extends" it is removed from Object. Thus the depth of 
  // java.lang.Object is 0, but the depth of java.io.FilterOutputStream 
  // is 2. Depth is defined for all regular and array classes, but not 
  // interfaces or primitive types.
   
  jclass klass0 = klass;
  jboolean has_interfaces = 0;
  while (klass0 != &java::lang::Object::class$)
    {
      has_interfaces += klass0->interface_count;
      klass0 = klass0->superclass;
      klass->depth++;
    }

  // We do class member testing in constant time by using a small table 
  // of all the ancestor classes within each class. The first element is 
  // a pointer to the current class, and the rest are pointers to the 
  // classes ancestors, ordered from the current class down by decreasing 
  // depth. We do not include java.lang.Object in the table of ancestors, 
  // since it is redundant.
	
  klass->ancestors = (jclass *) _Jv_Malloc (klass->depth * sizeof (jclass));
  klass0 = klass;
  for (int index = 0; index < klass->depth; index++)
    {
      klass->ancestors[index] = klass0;
      klass0 = klass0->superclass;
    }
    
  if (java::lang::reflect::Modifier::isAbstract (klass->accflags))
    return;
  
  // Optimization: If class implements no interfaces, use a common
  // predefined interface table.
  if (!has_interfaces)
    {
      klass->idt = &null_idt;
      return;
    }

  klass->idt = 
    (_Jv_IDispatchTable *) _Jv_Malloc (sizeof (_Jv_IDispatchTable));
    
  _Jv_ifaces ifaces;

  ifaces.count = 0;
  ifaces.len = INITIAL_IFACES_LEN;
  ifaces.list = (jclass *) _Jv_Malloc (ifaces.len * sizeof (jclass *));

  int itable_size = _Jv_GetInterfaces (klass, &ifaces);

  if (ifaces.count > 0)
    {
      klass->idt->cls.itable = 
	(void **) _Jv_Malloc (itable_size * sizeof (void *));
      klass->idt->cls.itable_length = itable_size;
          
      jshort *itable_offsets = 
	(jshort *) _Jv_Malloc (ifaces.count * sizeof (jshort));

      _Jv_GenerateITable (klass, &ifaces, itable_offsets);

      jshort cls_iindex = 
	_Jv_FindIIndex (ifaces.list, itable_offsets, ifaces.count);

      for (int i=0; i < ifaces.count; i++)
	{
	  ifaces.list[i]->idt->iface.ioffsets[cls_iindex] =
	    itable_offsets[i];
	}

      klass->idt->cls.iindex = cls_iindex;	    

      _Jv_Free (ifaces.list);
      _Jv_Free (itable_offsets);
    }
  else 
    {
      klass->idt->cls.iindex = SHRT_MAX;
    }
}

// Return index of item in list, or -1 if item is not present.
inline jshort
_Jv_IndexOf (void *item, void **list, jshort list_len)
{
  for (int i=0; i < list_len; i++)
    {
      if (list[i] == item)
        return i;
    }
  return -1;
}

// Find all unique interfaces directly or indirectly implemented by klass.
// Returns the size of the interface dispatch table (itable) for klass, which 
// is the number of unique interfaces plus the total number of methods that 
// those interfaces declare. May extend ifaces if required.
jshort
_Jv_GetInterfaces (jclass klass, _Jv_ifaces *ifaces)
{
  jshort result = 0;
  
  for (int i=0; i < klass->interface_count; i++)
    {
      jclass iface = klass->interfaces[i];
      if (_Jv_IndexOf (iface, (void **) ifaces->list, ifaces->count) == -1)
        {
	  if (ifaces->count + 1 >= ifaces->len)
	    {
	      /* Resize ifaces list */
	      ifaces->len = ifaces->len * 2;
	      ifaces->list = (jclass *) _Jv_Realloc (ifaces->list, 
	                     ifaces->len * sizeof(jclass));
	    }
	  ifaces->list[ifaces->count] = iface;
	  ifaces->count++;

	  result += _Jv_GetInterfaces (klass->interfaces[i], ifaces);
	}
    }
    
  if (klass->isInterface())
    {
      result += klass->method_count + 1;
    }
  else
    {
      if (klass->superclass)
        {
	  result += _Jv_GetInterfaces (klass->superclass, ifaces);
	}
    }
  return result;
}

// Fill out itable in klass, resolving method declarations in each ifaces.
// itable_offsets is filled out with the position of each iface in itable,
// such that itable[itable_offsets[n]] == ifaces.list[n].
void
_Jv_GenerateITable (jclass klass, _Jv_ifaces *ifaces, jshort *itable_offsets)
{
  void **itable = klass->idt->cls.itable;
  jshort itable_pos = 0;

  for (int i=0; i < ifaces->count; i++)
    { 
      jclass iface = ifaces->list[i];
      itable_offsets[i] = itable_pos;
      itable_pos = _Jv_AppendPartialITable (klass, iface, itable, itable_pos);
      
      /* Create interface dispatch table for iface */
      if (iface->idt == NULL)
	{
	  iface->idt = 
	    (_Jv_IDispatchTable *) _Jv_Malloc (sizeof (_Jv_IDispatchTable));

	  // The first element of ioffsets is its length (itself included).
	  jshort *ioffsets = 
	    (jshort *) _Jv_Malloc (INITIAL_IOFFSETS_LEN * sizeof (jshort));
	  ioffsets[0] = INITIAL_IOFFSETS_LEN;
	  for (int i=1; i < INITIAL_IOFFSETS_LEN; i++)
	    ioffsets[i] = -1;

	  iface->idt->iface.ioffsets = ioffsets;	    
	}
    }
}

// Format method name for use in error messages.
jstring
_Jv_GetMethodString (jclass klass, _Jv_Utf8Const *name)
{
  jstring r = JvNewStringUTF (klass->name->data);
  r = r->concat (JvNewStringUTF ("."));
  r = r->concat (JvNewStringUTF (name->data));
  return r;
}

void 
_Jv_ThrowNoSuchMethodError ()
{
  throw new java::lang::NoSuchMethodError;
}

// Each superinterface of a class (i.e. each interface that the class
// directly or indirectly implements) has a corresponding "Partial