libjava/resolve.cc

// resolve.cc - Code for linking and resolving classes and pool entries.

/* Copyright (C) 1999, 2000, 2001 , 2002, 2003 Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

/* Author: Kresten Krab Thorup <krab@gnu.org>  */

#include <config.h>

#include <java-interp.h>

#include <jvm.h>
#include <gcj/cni.h>
#include <string.h>
#include <java-cpool.h>
#include <java/lang/Class.h>
#include <java/lang/String.h>
#include <java/lang/StringBuffer.h>
#include <java/lang/Thread.h>
#include <java/lang/InternalError.h>
#include <java/lang/VirtualMachineError.h>
#include <java/lang/NoSuchFieldError.h>
#include <java/lang/NoSuchMethodError.h>
#include <java/lang/ClassFormatError.h>
#include <java/lang/IllegalAccessError.h>
#include <java/lang/AbstractMethodError.h>
#include <java/lang/NoClassDefFoundError.h>
#include <java/lang/IncompatibleClassChangeError.h>
#include <java/lang/reflect/Modifier.h>

using namespace gcj;

void
_Jv_ResolveField (_Jv_Field *field, java::lang::ClassLoader *loader)
{
  if (! field->isResolved ())
    {
      _Jv_Utf8Const *sig = (_Jv_Utf8Const*)field->type;
      field->type = _Jv_FindClassFromSignature (sig->data, loader);
      field->flags &= ~_Jv_FIELD_UNRESOLVED_FLAG;
    }
}

#ifdef INTERPRETER

static void throw_internal_error (char *msg)
	__attribute__ ((__noreturn__));
static void throw_class_format_error (jstring msg)
	__attribute__ ((__noreturn__));
static void throw_class_format_error (char *msg)
	__attribute__ ((__noreturn__));

static int get_alignment_from_class (jclass);

static _Jv_ResolvedMethod* 
_Jv_BuildResolvedMethod (_Jv_Method*,
			 jclass,
			 jboolean,
			 jint);


static void throw_incompatible_class_change_error (jstring msg)
{
  throw new java::lang::IncompatibleClassChangeError (msg);
}

_Jv_word
_Jv_ResolvePoolEntry (jclass klass, int index)
{
  using namespace java::lang::reflect;

  _Jv_Constants *pool = &klass->constants;

  if ((pool->tags[index] & JV_CONSTANT_ResolvedFlag) != 0)
    return pool->data[index];

  switch (pool->tags[index]) {
  case JV_CONSTANT_Class:
    {
      _Jv_Utf8Const *name = pool->data[index].utf8;

      jclass found;
      if (name->data[0] == '[')
	found = _Jv_FindClassFromSignature (&name->data[0],
					    klass->loader);
      else
	found = _Jv_FindClass (name, klass->loader);

      if (! found)
	{
	  jstring str = _Jv_NewStringUTF (name->data);
	  // This exception is specified in JLS 2nd Ed, section 5.1.
	  throw new java::lang::NoClassDefFoundError (str);
	}

      if ((found->accflags & Modifier::PUBLIC) == Modifier::PUBLIC
	  || (_Jv_ClassNameSamePackage (found->name,
					klass->name)))
	{
	  pool->data[index].clazz = found;
	  pool->tags[index] |= JV_CONSTANT_ResolvedFlag;
	}
      else
	{
	  throw new java::lang::IllegalAccessError (found->getName());
	}
    }
    break;

  case JV_CONSTANT_String:
    {
      jstring str;
      str = _Jv_NewStringUtf8Const (pool->data[index].utf8);
      pool->data[index].o = str;
      pool->tags[index] |= JV_CONSTANT_ResolvedFlag;
    }
    break;


  case JV_CONSTANT_Fieldref:
    {
      _Jv_ushort class_index, name_and_type_index;
      _Jv_loadIndexes (&pool->data[index],
		       class_index,
		       name_and_type_index);
      jclass owner = (_Jv_ResolvePoolEntry (klass, class_index)).clazz;

      if (owner != klass)
	_Jv_InitClass (owner);

      _Jv_ushort name_index, type_index;
      _Jv_loadIndexes (&pool->data[name_and_type_index],
		       name_index,
		       type_index);

      _Jv_Utf8Const *field_name = pool->data[name_index].utf8;
      _Jv_Utf8Const *field_type_name = pool->data[type_index].utf8;

      // FIXME: The implementation of this function
      // (_Jv_FindClassFromSignature) will generate an instance of
      // _Jv_Utf8Const for each call if the field type is a class name
      // (Lxx.yy.Z;).  This may be too expensive to do for each and
      // every fieldref being resolved.  For now, we fix the problem by
      // only doing it when we have a loader different from the class
      // declaring the field.

      jclass field_type = 0;

      if (owner->loader != klass->loader)
	field_type = _Jv_FindClassFromSignature (field_type_name->data,
						 klass->loader);
      
      _Jv_Field* the_field = 0;

      for (jclass cls = owner; cls != 0; cls = cls->getSuperclass ())
	{
	  for (int i = 0;  i < cls->field_count;  i++)
	    {
	      _Jv_Field *field = &cls->fields[i];
	      if (! _Jv_equalUtf8Consts (field->name, field_name))
		continue;

	      // now, check field access. 

	      if (   (cls == klass)
		  || ((field->flags & Modifier::PUBLIC) != 0)
		  || (((field->flags & Modifier::PROTECTED) != 0)
		      && cls->isAssignableFrom (klass))
		  || (((field->flags & Modifier::PRIVATE) == 0)
		      && _Jv_ClassNameSamePackage (cls->name,
						   klass->name)))
		{
		  /* resove the field using the class' own loader
		     if necessary */

		  if (!field->isResolved ())
		    _Jv_ResolveField (field, cls->loader);

		  if (field_type != 0 && field->type != field_type)
		    throw new java::lang::LinkageError
		      (JvNewStringLatin1 
		       ("field type mismatch with different loaders"));

		  the_field = field;
		  goto end_of_field_search;
		}
	      else
		{
		  throw new java::lang::IllegalAccessError;
		}
	    }
	}

    end_of_field_search:
      if (the_field == 0)
	{
	  java::lang::StringBuffer *sb = new java::lang::StringBuffer();
	  sb->append(JvNewStringLatin1("field "));
	  sb->append(owner->getName());
	  sb->append(JvNewStringLatin1("."));
	  sb->append(_Jv_NewStringUTF(field_name->data));
	  sb->append(JvNewStringLatin1(" was not found."));
	  throw_incompatible_class_change_error(sb->toString());
	}

      pool->data[index].field = the_field;
      pool->tags[index] |= JV_CONSTANT_ResolvedFlag;
    }
    break;

  case JV_CONSTANT_Methodref:
  case JV_CONSTANT_InterfaceMethodref:
    {
      _Jv_ushort class_index, name_and_type_index;
      _Jv_loadIndexes (&pool->data[index],
		       class_index,
		       name_and_type_index);
      jclass owner = (_Jv_ResolvePoolEntry (klass, class_index)).clazz;

      if (owner != klass)
	_Jv_InitClass (owner);

      _Jv_ushort name_index, type_index;
      _Jv_loadIndexes (&pool->data[name_and_type_index],
		       name_index,
		       type_index);

      _Jv_Utf8Const *method_name = pool->data[name_index].utf8;
      _Jv_Utf8Const *method_signature = pool->data[type_index].utf8;

      _Jv_Method *the_method = 0;
      jclass found_class = 0;

      // First search the class itself.
      the_method = _Jv_SearchMethodInClass (owner, klass, 
					    method_name, method_signature);

      if (the_method != 0)
        {
	  found_class = owner;
          goto end_of_method_search;
	}

      // If we are resolving an interface method, search the
      // interface's superinterfaces (A superinterface is not an
      // interface's superclass - a superinterface is implemented by
      // the interface).
      if (pool->tags[index] == JV_CONSTANT_InterfaceMethodref)
        {
	  _Jv_ifaces ifaces;
	  ifaces.count = 0;
	  ifaces.len = 4;
	  ifaces.list = (jclass *) _Jv_Malloc (ifaces.len * sizeof (jclass *));

	  _Jv_GetInterfaces (owner, &ifaces);	  

	  for (int i = 0; i < ifaces.count; i++)
	    {
	      jclass cls = ifaces.list[i];
	      the_method = _Jv_SearchMethodInClass (cls, klass, method_name, 
	                                            method_signature);
	      if (the_method != 0)
	        {
		  found_class = cls;
                  break;
		}
	    }

	  _Jv_Free (ifaces.list);

	  if (the_method != 0)
	    goto end_of_method_search;
	}

      // Finally, search superclasses. 
      for (jclass cls = owner->getSuperclass (); cls != 0; 
           cls = cls->getSuperclass ())
	{
	  the_method = _Jv_SearchMethodInClass (cls, klass, 
						method_name, method_signature);
          if (the_method != 0)
	    {
	      found_class = cls;
	      break;
	    }
	}

    end_of_method_search:
    
      // FIXME: if (cls->loader != klass->loader), then we
      // must actually check that the types of arguments
      // correspond.  That is, for each argument type, and
      // the return type, doing _Jv_FindClassFromSignature
      // with either loader should produce the same result,
      // i.e., exactly the same jclass object. JVMS 5.4.3.3    
    
      if (the_method == 0)
	{
	  java::lang::StringBuffer *sb = new java::lang::StringBuffer();
	  sb->append(JvNewStringLatin1("method "));
	  sb->append(owner->getName());
	  sb->append(JvNewStringLatin1("."));
	  sb->append(_Jv_NewStringUTF(method_name->data));
	  sb->append(JvNewStringLatin1(" was not found."));
	  throw new java::lang::NoSuchMethodError (sb->toString());
	}
      
      int vtable_index = -1;
      if (pool->tags[index] != JV_CONSTANT_InterfaceMethodref)
	vtable_index = (jshort)the_method->index;

      pool->data[index].rmethod = 
	_Jv_BuildResolvedMethod(the_method,
				found_class,
				(the_method->accflags & Modifier::STATIC) != 0,
				vtable_index);
      pool->tags[index] |= JV_CONSTANT_ResolvedFlag;
    }
    break;

  }

  return pool->data[index];
}

// Find a method declared in the cls that is referenced from klass and
// perform access checks.
_Jv_Method *
_Jv_SearchMethodInClass (jclass cls, jclass klass, 
                         _Jv_Utf8Const *method_name, 
			 _Jv_Utf8Const *method_signature)
{
  using namespace java::lang::reflect;

  for (int i = 0;  i < cls->method_count;  i++)
    {
      _Jv_Method *method = &cls->methods[i];
      if (   (!_Jv_equalUtf8Consts (method->name,
				    method_name))
	  || (!_Jv_equalUtf8Consts (method->signature,
				    method_signature)))
	continue;

      if (cls == klass 
	  || ((method->accflags & Modifier::PUBLIC) != 0)
	  || (((method->accflags & Modifier::PROTECTED) != 0)
	      && cls->isAssignableFrom (klass))
	  || (((method->accflags & Modifier::PRIVATE) == 0)
	      && _Jv_ClassNameSamePackage (cls->name,
					   klass->name)))
	{
	  return method;
	}
      else
	{
	  throw new java::lang::IllegalAccessError;
	}
    }
  return 0;
}

// A helper for _Jv_PrepareClass.  This adds missing `Miranda methods'
// to a class.
void
_Jv_PrepareMissingMethods (jclass base2, jclass iface_class)
{
  _Jv_InterpClass *base = reinterpret_cast<_Jv_InterpClass *> (base2);
  for (int i = 0; i < iface_class->interface_count; ++i)
    {
      for (int j = 0; j < iface_class->interfaces[i]->method_count; ++j)
	{
	  _Jv_Method *meth = &iface_class->interfaces[i]->methods[j];
	  // Don't bother with <clinit>.
	  if (meth->name->data[0] == '<')
	    continue;
	  _Jv_Method *new_meth = _Jv_LookupDeclaredMethod (base, meth->name,
							   meth->signature);
	  if (! new_meth)
	    {
	      // We assume that such methods are very unlikely, so we
	      // just reallocate the method array each time one is
	      // found.  This greatly simplifies the searching --
	      // otherwise we have to make sure that each such method
	      // found is really unique among all superinterfaces.
	      int new_count = base->method_count + 1;
	      _Jv_Method *new_m
		= (_Jv_Method *) _Jv_AllocBytes (sizeof (_Jv_Method)
						 * new_count);
	      memcpy (new_m, base->methods,
		      sizeof (_Jv_Method) * base->method_count);

	      // Add new method.
	      new_m[base->method_count] = *meth;
	      new_m[base->method_count].index = (_Jv_ushort) -1;
	      new_m[base->method_count].accflags
		|= java::lang::reflect::Modifier::INVISIBLE;

	      _Jv_MethodBase **new_im
		= (_Jv_MethodBase **) _Jv_AllocBytes (sizeof (_Jv_MethodBase *)
						      * new_count);
	      memcpy (new_im, base->interpreted_methods,
		      sizeof (_Jv_MethodBase *) * base->method_count);

	      base->methods = new_m;
	      base->interpreted_methods = new_im;
	      base->method_count = new_count;
	    }
	}

      _Jv_PrepareMissingMethods (base, iface_class->interfaces[i]);
    }
}

void 
_Jv_PrepareClass(jclass klass)
{
  using namespace java::lang::reflect;

 /*
  * The job of this function is to: 1) assign storage to fields, and 2)
  * build the vtable.  static fields are assigned real memory, instance
  * fields are assigned offsets.
  *
  * NOTE: we have a contract with the garbage collector here.  Static
  * reference fields must not be resolved, until after they have storage
  * assigned which is the check used by the collector to see if it
  * should indirect the static field reference and mark the object
  * pointed to. 
  *
  * Most fields are resolved lazily (i.e. have their class-type
  * assigned) when they are accessed the first time by calling as part
  * of _Jv_ResolveField, which is allways called after _Jv_PrepareClass.
  * Static fields with initializers are resolved as part of this
  * function, as are fields with primitive types.
  */

  if (! _Jv_IsInterpretedClass (klass))
    return;

  if (klass->state >= JV_STATE_PREPARED)
    return;

  // Make sure super-class is linked.  This involves taking a lock on
  // the super class, so we use the Java method resolveClass, which
  // will unlock it properly, should an exception happen.  If there's
  // no superclass, do nothing -- Object will already have been
  // resolved.

  if (klass->superclass)
    java::lang::ClassLoader::resolveClass0 (klass->superclass);

  _Jv_InterpClass *clz = (_Jv_InterpClass*)klass;

  /************ PART ONE: OBJECT LAYOUT ***************/

  int instance_size;
  int static_size;

  // Although java.lang.Object is never interpreted, an interface can
  // have a null superclass.
  if (clz->superclass)
    instance_size = clz->superclass->size();
  else
    instance_size = java::lang::Object::class$.size();
  static_size   = 0;

  for (int i = 0; i < clz->field_count; i++)
    {
      int field_size;
      int field_align;

      _Jv_Field *field = &clz->fields[i];

      if (! field->isRef ())
	{
	  // it's safe to resolve the field here, since it's 
	  // a primitive class, which does not cause loading to happen.
	  _Jv_ResolveField (field, clz->loader);

	  field_size = field->type->size ();
	  field_align = get_alignment_from_class (field->type);
	}
      else 
	{
	  field_size = sizeof (jobject);
	  field_align = __alignof__ (jobject);
	}

#ifndef COMPACT_FIELDS
      field->bsize = field_size;
#endif

      if (field->flags & Modifier::STATIC)
	{
	  /* this computes an offset into a region we'll allocate 
	     shortly, and then add this offset to the start address */

	  static_size        = ROUND (static_size, field_align);
	  field->u.boffset   = static_size;
	  static_size       += field_size;
	}
      else
	{
	  instance_size      = ROUND (instance_size, field_align);
	  field->u.boffset   = instance_size;
	  instance_size     += field_size;
	}
    }

  // set the instance size for the class
  clz->size_in_bytes = instance_size;

  // allocate static memory
  if (static_size != 0)
    {
      char *static_data = (char*)_Jv_AllocBytes (static_size);

      memset (static_data, 0, static_size);

      for (int i = 0; i < clz->field_count; i++)
	{
	  _Jv_Field *field = &clz->fields[i];

	  if ((field->flags & Modifier::STATIC) != 0)
	    {
	      field->u.addr  = static_data + field->u.boffset;
			    
	      if (clz->field_initializers[i] != 0)
		{
		  _Jv_ResolveField (field, clz->loader);
		  _Jv_InitField (0, clz, i);
		}
	    }
	}

      // now we don't need the field_initializers anymore, so let the
      // collector get rid of it!

      clz->field_initializers = 0;
    }

  /************ PART TWO: VTABLE LAYOUT ***************/

  /* preparation: build the vtable stubs (even interfaces can)
     have code -- for static constructors. */
  for (int i = 0; i < clz->method_count; i++)
    {
      _Jv_MethodBase *imeth = clz->interpreted_methods[i];

      if ((clz->methods[i].accflags & Modifier::NATIVE) != 0)
	{
	  // You might think we could use a virtual `ncode' method in
	  // the _Jv_MethodBase and unify the native and non-native
	  // cases.  Well, we can't, because we don't allocate these
	  // objects using `new', and thus they don't get a vtable.
	  _Jv_JNIMethod *jnim = reinterpret_cast<_Jv_JNIMethod *> (imeth);
	  clz->methods[i].ncode = jnim->ncode ();
	}
      else if (imeth != 0)		// it could be abstract
	{
	  _Jv_InterpMethod *im = reinterpret_cast<_Jv_InterpMethod *> (imeth);
	  _Jv_VerifyMethod (im);
	  clz->methods[i].ncode = im->ncode ();
	}
    }

  if ((clz->accflags & Modifier::INTERFACE))
    {
      clz->state = JV_STATE_PREPARED;
      clz->notifyAll ();
      return;
    }

  // A class might have so-called "Miranda methods".  This is a method
  // that is declared in an interface and not re-declared in an
  // abstract class.  Some compilers don't emit declarations for such
  // methods in the class; this will give us problems since we expect
  // a declaration for any method requiring a vtable entry.  We handle
  // this here by searching for such methods and constructing new
  // internal declarations for them.  We only need to do this for
  // abstract classes.
  if ((clz->accflags & Modifier::ABSTRACT))
    _Jv_PrepareMissingMethods (clz, clz);

  clz->vtable_method_count = -1;
  _Jv_MakeVTable (clz);

  /* wooha! we're done. */
  clz->state = JV_STATE_PREPARED;
  clz->notifyAll ();
}

/** Do static initialization for fields with a constant initializer */
void
_Jv_InitField (jobject obj, jclass klass, int index)
{
  using namespace java::lang::reflect;

  if (obj != 0 && klass == 0)
    klass = obj->getClass ();

  if (!_Jv_IsInterpretedClass (klass))
    return;

  _Jv_InterpClass *clz = (_Jv_InterpClass*)klass;

  _Jv_Field * field = (&clz->fields[0]) + index;

  if (index > clz->field_count)
    throw_internal_error ("field out of range");

  int init = clz->field_initializers[index];
  if (init == 0)
    return;

  _Jv_Constants *pool = &clz->constants;
  int tag = pool->tags[init];

  if (! field->isResolved ())
    throw_internal_error ("initializing unresolved field");

  if (obj==0 && ((field->flags & Modifier::STATIC) == 0))
    throw_internal_error ("initializing non-static field with no object");

  void *addr = 0;

  if ((field->flags & Modifier::STATIC) != 0)
    addr = (void*) field->u.addr;
  else
    addr = (void*) (((char*)obj) + field->u.boffset);

  switch (tag)
    {
    case JV_CONSTANT_String:
      {
	_Jv_MonitorEnter (clz);
	jstring str;
	str = _Jv_NewStringUtf8Const (pool->data[init].utf8);
	pool->data[init].string = str;
	pool->tags[init] = JV_CONSTANT_ResolvedString;
	_Jv_MonitorExit (clz);
      }
      /* fall through */

    case JV_CONSTANT_ResolvedString:
      if (! (field->type == &StringClass
 	     || field->type == &java::lang::Class::class$))
	throw_class_format_error ("string initialiser to non-string field");

      *(jstring*)addr = pool->data[init].string;
      break;

    case JV_CONSTANT_Integer:
      {
	int value = pool->data[init].i;

	if (field->type == JvPrimClass (boolean))
	  *(jboolean*)addr = (jboolean)value;
	
	else if (field->type == JvPrimClass (byte))
	  *(jbyte*)addr = (jbyte)value;
	
	else if (field->type == JvPrimClass (char))
	  *(jchar*)addr = (jchar)value;

	else if (field->type == JvPrimClass (short))
	  *(jshort*)addr = (jshort)value;
	
	else if (field->type == JvPrimClass (int))
	  *(jint*)addr = (jint)value;

	else
	  throw_class_format_error ("erroneous field initializer");
      }  
      break;

    case JV_CONSTANT_Long:
      if (field->type != JvPrimClass (long))
	throw_class_format_error ("erroneous field initializer");

      *(jlong*)addr = _Jv_loadLong (&pool->data[init]);
      break;

    case JV_CONSTANT_Float:
      if (field->type != JvPrimClass (float))
	throw_class_format_error ("erroneous field initializer");

      *(jfloat*)addr = pool->data[init].f;
      break;

    case JV_CONSTANT_Double:
      if (field->type != JvPrimClass (double))
	throw_class_format_error ("erroneous field initializer");

      *(jdouble*)addr = _Jv_loadDouble (&pool->data[init]);
      break;

    default:
      throw_class_format_error ("erroneous field initializer");
    }
}

static int
get_alignment_from_class (jclass klass)
{
  if (klass == JvPrimClass (byte))
    return  __alignof__ (jbyte);
  else if (klass == JvPrimClass (short))
    return  __alignof__ (jshort);
  else if (klass == JvPrimClass (int)) 
    return  __alignof__ (jint);
  else if (klass == JvPrimClass (long))
    return  __alignof__ (jlong);
  else if (klass == JvPrimClass (boolean))
    return  __alignof__ (jboolean);
  else if (klass == JvPrimClass (char))
    return  __alignof__ (jchar);
  else if (klass == JvPrimClass (float))
    return  __alignof__ (jfloat);
  else if (klass == JvPrimClass (double))
    return  __alignof__ (jdouble);
  else
    return __alignof__ (jobject);
}


inline static unsigned char*
skip_one_type (unsigned char* ptr)
{
  int ch = *ptr++;

  while (ch == '[')
    { 
      ch = *ptr++;
    }
  
  if (ch == 'L')
    {
      do { ch = *ptr++; } while (ch != ';');
    }

  return ptr;
}

static ffi_type*
get_ffi_type_from_signature (unsigned char* ptr)
{
  switch (*ptr) 
    {
    case 'L':
    case '[':
      return &ffi_type_pointer;
      break;

    case 'Z':
      // On some platforms a bool is a byte, on others an int.
      if (sizeof (jboolean) == sizeof (jbyte))
	return &ffi_type_sint8;
      else
	{
	  JvAssert (sizeof (jbyte) == sizeof (jint));
	  return &ffi_type_sint32;
	}
      break;

    case 'B':
      return &ffi_type_sint8;
      break;
      
    case 'C':
      return &ffi_type_uint16;
      break;
	  
    case 'S': 
      return &ffi_type_sint16;
      break;
	  
    case 'I':
      return &ffi_type_sint32;
      break;
	  
    case 'J':
      return &ffi_type_sint64;
      break;
	  
    case 'F':
      return &ffi_type_float;
      break;
	  
    case 'D':
      return &ffi_type_double;
      break;

    case 'V':
      return &ffi_type_void;
      break;
    }

  throw_internal_error ("unknown type in signature");
}

/* this function yields the number of actual arguments, that is, if the
 * function is non-static, then one is added to the number of elements
 * found in the signature */

int 
_Jv_count_arguments (_Jv_Utf8Const *signature,
		     jboolean staticp)
{
  unsigned char *ptr = (unsigned char*) signature->data;
  int arg_count = staticp ? 0 : 1;

  /* first, count number of arguments */

  // skip '('
  ptr++;

  // count args
  while (*ptr != ')')
    {
      ptr = skip_one_type (ptr);
      arg_count += 1;
    }

  return arg_count;
}

/* This beast will build a cif, given the signature.  Memory for
 * the cif itself and for the argument types must be allocated by the
 * caller.
 */

static int 
init_cif (_Jv_Utf8Const* signature,
	  int arg_count,
	  jboolean staticp,
	  ffi_cif *cif,
	  ffi_type **arg_types,
	  ffi_type **rtype_p)
{
  unsigned char *ptr = (unsigned char*) signature->data;

  int arg_index = 0;		// arg number
  int item_count = 0;		// stack-item count

  // setup receiver
  if (!staticp)
    {
      arg_types[arg_index++] = &ffi_type_pointer;
      item_count += 1;
    }

  // skip '('
  ptr++;

  // assign arg types
  while (*ptr != ')')
    {
      arg_types[arg_index++] = get_ffi_type_from_signature (ptr);

      if (*ptr == 'J' || *ptr == 'D')
	item_count += 2;
      else
	item_count += 1;

      ptr = skip_one_type (ptr);
    }

  // skip ')'
  ptr++;
  ffi_type *rtype = get_ffi_type_from_signature (ptr);

  ptr = skip_one_type (ptr);
  if (ptr != (unsigned char*)signature->data + signature->length)
    throw_internal_error ("did not find end of signature");

  if (ffi_prep_cif (cif, FFI_DEFAULT_ABI,
		    arg_count, rtype, arg_types) != FFI_OK)
    throw_internal_error ("ffi_prep_cif failed");

  if (rtype_p != NULL)
    *rtype_p = rtype;

  return item_count;
}

#if FFI_NATIVE_RAW_API
#   define FFI_PREP_RAW_CLOSURE ffi_prep_raw_closure
#   define FFI_RAW_SIZE ffi_raw_size
#else
#   define FFI_PREP_RAW_CLOSURE ffi_prep_java_raw_closure
#   define FFI_RAW_SIZE ffi_java_raw_size
#endif

/* we put this one here, and not in interpret.cc because it
 * calls the utility routines _Jv_count_arguments 
 * which are static to this module.  The following struct defines the
 * layout we use for the stubs, it's only used in the ncode method. */

typedef struct {
  ffi_raw_closure  closure;
  ffi_cif   cif;
  ffi_type *arg_types[0];
} ncode_closure;

typedef void (*ffi_closure_fun) (ffi_cif*,void*,ffi_raw*,void*);

void *
_Jv_InterpMethod::ncode ()
{
  using namespace java::lang::reflect;

  if (self->ncode != 0)
    return self->ncode;

  jboolean staticp = (self->accflags & Modifier::STATIC) != 0;
  int arg_count = _Jv_count_arguments (self->signature, staticp);

  ncode_closure *closure =
    (ncode_closure*)_Jv_AllocBytes (sizeof (ncode_closure)
					+ arg_count * sizeof (ffi_type*));

  init_cif (self->signature,
	    arg_count,
	    staticp,
	    &closure->cif,
	    &closure->arg_types[0],
	    NULL);

  ffi_closure_fun fun;

  args_raw_size = FFI_RAW_SIZE (&closure->cif);

  JvAssert ((self->accflags & Modifier::NATIVE) == 0);

  if ((self->accflags & Modifier::SYNCHRONIZED) != 0)
    {
      if (staticp)
	fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_class;
      else
	fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_object; 
    }
  else
    {
      fun = (ffi_closure_fun)&_Jv_InterpMethod::run_normal;
    }

  FFI_PREP_RAW_CLOSURE (&closure->closure,
		        &closure->cif, 
		        fun,
		        (void*)this);

  self->ncode = (void*)closure;
  return self->ncode;
}


void *
_Jv_JNIMethod::ncode ()
{
  using namespace java::lang::reflect;

  if (self->ncode != 0)
    return self->ncode;

  jboolean staticp = (self->accflags & Modifier::STATIC) != 0;
  int arg_count = _Jv_count_arguments (self->signature, staticp);

  ncode_closure *closure =
    (ncode_closure*)_Jv_AllocBytes (sizeof (ncode_closure)
				    + arg_count * sizeof (ffi_type*));

  ffi_type *rtype;
  init_cif (self->signature,
	    arg_count,
	    staticp,
	    &closure->cif,
	    &closure->arg_types[0],
	    &rtype);

  ffi_closure_fun fun;

  args_raw_size = FFI_RAW_SIZE (&closure->cif);

  // Initialize the argument types and CIF that represent the actual
  // underlying JNI function.
  int extra_args = 1;
  if ((self->accflags & Modifier::STATIC))
    ++extra_args;
  jni_arg_types = (ffi_type **) _Jv_Malloc ((extra_args + arg_count)
					    * sizeof (ffi_type *));
  int offset = 0;
  jni_arg_types[offset++] = &ffi_type_pointer;
  if ((self->accflags & Modifier::STATIC))
    jni_arg_types[offset++] = &ffi_type_pointer;
  memcpy (&jni_arg_types[offset], &closure->arg_types[0],
	  arg_count * sizeof (ffi_type *));

  // NOTE: This must agree with the JNICALL definition in jni.h
#ifdef WIN32
#define FFI_JNI_ABI FFI_STDCALL
#else
#define FFI_JNI_ABI FFI_DEFAULT_ABI
#endif

  if (ffi_prep_cif (&jni_cif, FFI_JNI_ABI,
		    extra_args + arg_count, rtype,
		    jni_arg_types) != FFI_OK)
    throw_internal_error ("ffi_prep_cif failed for JNI function");

  JvAssert ((self->accflags & Modifier::NATIVE) != 0);

  // FIXME: for now we assume that all native methods for
  // interpreted code use JNI.
  fun = (ffi_closure_fun) &_Jv_JNIMethod::call;

  FFI_PREP_RAW_CLOSURE (&closure->closure,
			&closure->cif, 
			fun,
			(void*) this);

  self->ncode = (void *) closure;
  return self->ncode;
}


/* A _Jv_ResolvedMethod is what is put in the constant pool for a
 * MethodRef or InterfacemethodRef.  */
static _Jv_ResolvedMethod*
_Jv_BuildResolvedMethod (_Jv_Method* method,
			 jclass      klass,
			 jboolean staticp,
			 jint vtable_index)
{
  int arg_count = _Jv_count_arguments (method->signature, staticp);

  _Jv_ResolvedMethod* result = (_Jv_ResolvedMethod*)
    _Jv_AllocBytes (sizeof (_Jv_ResolvedMethod)
		    + arg_count*sizeof (ffi_type*));

  result->stack_item_count
    = init_cif (method->signature,
		arg_count,
		staticp,
		&result->cif,
		&result->arg_types[0],
		NULL);

  result->vtable_index        = vtable_index;
  result->method              = method;
  result->klass               = klass;

  return result;
}


static void
throw_class_format_error (jstring msg)
{
  throw (msg
	 ? new java::lang::ClassFormatError (msg)
	 : new java::lang::ClassFormatError);
}

static void
throw_class_format_error (char *msg)
{
  throw_class_format_error (JvNewStringLatin1 (msg));
}

static void
throw_internal_error (char *msg)
{
  throw new java::lang::InternalError (JvNewStringLatin1 (msg));
}


#endif /* INTERPRETER */