natmethod.cc

gcc的组建

  jboolean needs_this = false;
  if (is_constructor
      || ! Modifier::isStatic(meth->accflags))
    needs_this = true;

  int param_count = parameter_types->length;
  if (needs_this)
    ++param_count;

  ffi_type *rtype;
  // A constructor itself always returns void.
  if (is_constructor || return_type == JvPrimClass (void))
    rtype = &ffi_type_void;
  else
    rtype = get_ffi_type (return_type);
  ffi_type **argtypes = (ffi_type **) __builtin_alloca (param_count
							* sizeof (ffi_type *));

  jclass *paramelts = elements (parameter_types);

  // Special case for the `this' argument of a constructor.  Note that
  // the JDK 1.2 docs specify that the new object must be allocated
  // before argument conversions are done.
  if (is_constructor)
    obj = _Jv_AllocObject (return_type);

  const int size_per_arg = sizeof(jvalue);
  ffi_cif cif;

  char *p = (char *) __builtin_alloca (param_count * size_per_arg);
		// Overallocate to get correct alignment.
  void **values = (void **)
			__builtin_alloca (param_count * sizeof (void *));

  int i = 0;
  if (needs_this)
    {
      // The `NULL' type is `Object'.
      argtypes[i] = get_ffi_type (NULL);
      values[i] = p;
      memcpy (p, &obj, sizeof (jobject));
      p += size_per_arg;
      ++i;
    }

  for (int arg = 0; i < param_count; ++i, ++arg)
    {
      int tsize;

      argtypes[i] = get_ffi_type (paramelts[arg]);
      if (paramelts[arg]->isPrimitive())
	tsize = paramelts[arg]->size();
      else
	tsize = sizeof (jobject);

      // Copy appropriate bits from the jvalue into the ffi array.
      // FIXME: we could do this copying all in one loop, above, by
      // over-allocating a bit.
      // How do we do this without breaking big-endian platforms?
      values[i] = p;
      memcpy (p, &args[arg], tsize);
      p += size_per_arg;
    }

  if (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, param_count,
		    rtype, argtypes) != FFI_OK)
    throw new java::lang::VirtualMachineError(JvNewStringLatin1("internal error: ffi_prep_cif failed"));

  using namespace java::lang;
  using namespace java::lang::reflect;

  union
  {
    ffi_arg i;
    jobject o;
    jlong l;
    jfloat f;
    jdouble d;
  } ffi_result;

  switch (rtype->type)
    {
    case FFI_TYPE_VOID:
      break;
    case FFI_TYPE_SINT8:
      result->b = 0;
      break;
    case FFI_TYPE_SINT16:
      result->s = 0;
      break;
    case FFI_TYPE_UINT16:
      result->c = 0;
      break;
    case FFI_TYPE_SINT32:
      result->i = 0;
      break;
    case FFI_TYPE_SINT64:
      result->j = 0;
      break;
    case FFI_TYPE_FLOAT:
      result->f = 0;
      break;
    case FFI_TYPE_DOUBLE:
      result->d = 0;
      break;
    case FFI_TYPE_POINTER:
      result->l = 0;
      break;
    default:
      JvFail ("Unknown ffi_call return type");
      break;
    }

  void *ncode;

  // FIXME: If a vtable index is -1 at this point it is invalid, so we
  // have to use the ncode.  
  //
  // This can happen because methods in final classes don't have
  // vtable entries, but _Jv_isVirtualMethod() doesn't know that.  We
  // could solve this problem by allocating a vtable index for methods
  // in final classes.
  if (is_virtual_call 
      && ! Modifier::isFinal (meth->accflags)
      && (_Jv_ushort)-1 != meth->index)
    {
      _Jv_VTable *vtable = *(_Jv_VTable **) obj;
      if (iface == NULL)
	{
	  if (is_jni_call && Modifier::isAbstract (meth->accflags))
	    {
	      // With JNI we don't know if this is an interface call
	      // or a call to an abstract method.  Look up the method
	      // by name, the slow way.
	      _Jv_Method *concrete_meth
		= _Jv_LookupDeclaredMethod (vtable->clas,
					    meth->name,
					    meth->signature,
					    NULL);
	      if (concrete_meth == NULL
		  || concrete_meth->ncode == NULL
		  || Modifier::isAbstract(concrete_meth->accflags))
		throw new java::lang::IncompatibleClassChangeError
		  (_Jv_GetMethodString (vtable->clas, meth));
	      ncode = concrete_meth->ncode;
	    }
	  else
	    ncode = vtable->get_method (meth->index);
	}
      else
	ncode = _Jv_LookupInterfaceMethodIdx (vtable->clas, iface,
					      meth->index);
    }
  else
    {
      ncode = meth->ncode;
    }

  try
    {
      ffi_call (&cif, (void (*)()) ncode, &ffi_result, values);
    }
  catch (Throwable *ex)
    {
      // For JNI we just throw the real error.  For reflection, we
      // wrap the underlying method's exception in an
      // InvocationTargetException.
      if (! is_jni_call)
	ex = new InvocationTargetException (ex);
      throw ex;
    }

  // Since ffi_call returns integer values promoted to a word, use
  // a narrowing conversion for jbyte, jchar, etc. results.
  // Note that boolean is handled either by the FFI_TYPE_SINT8 or
  // FFI_TYPE_SINT32 case.
  if (is_constructor)
    result->l = obj;
  else
    {
      switch (rtype->type)
	{
	case FFI_TYPE_VOID:
	  break;
	case FFI_TYPE_SINT8:
	  result->b = (jbyte)ffi_result.i;
	  break;
	case FFI_TYPE_SINT16:
	  result->s = (jshort)ffi_result.i;
	  break;
	case FFI_TYPE_UINT16:
	  result->c = (jchar)ffi_result.i;
	  break;
	case FFI_TYPE_SINT32:
	  result->i = (jint)ffi_result.i;
	  break;
	case FFI_TYPE_SINT64:
	  result->j = (jlong)ffi_result.l;
	  break;
	case FFI_TYPE_FLOAT:
	  result->f = (jfloat)ffi_result.f;
	  break;
	case FFI_TYPE_DOUBLE:
	  result->d = (jdouble)ffi_result.d;
	  break;
	case FFI_TYPE_POINTER:
	  result->l = (jobject)ffi_result.o;
	  break;
	default:
	  JvFail ("Unknown ffi_call return type");
	  break;
	}
    }
#else
  throw new java::lang::UnsupportedOperationException(JvNewStringLatin1("reflection not available in this build"));
#endif // USE_LIBFFI
}

// This is another version of _Jv_CallAnyMethodA, but this one does
// more checking and is used by the reflection (and not JNI) code.
jobject
_Jv_CallAnyMethodA (jobject obj,
		    jclass return_type,
		    jmethodID meth,
		    jboolean is_constructor,
		    JArray<jclass> *parameter_types,
		    jobjectArray args,
		    jclass iface)
{
  if (parameter_types->length == 0 && args == NULL)
    {
      // The JDK accepts this, so we do too.
    }
  else if (parameter_types->length != args->length)
    throw new java::lang::IllegalArgumentException;

  int param_count = parameter_types->length;

  jclass *paramelts = elements (parameter_types);
  jobject *argelts = args == NULL ? NULL : elements (args);
  jvalue argvals[param_count];

#define COPY(Where, What, Type) \
  do { \
    Type val = (What); \
    memcpy ((Where), &val, sizeof (Type)); \
  } while (0)

  for (int i = 0; i < param_count; ++i)
    {
      jclass k = argelts[i] ? argelts[i]->getClass() : NULL;
      if (paramelts[i]->isPrimitive())
	{
	  if (! argelts[i]
	      || ! k
	      || ! can_widen (k, paramelts[i]))
	    throw new java::lang::IllegalArgumentException;
	    
	  if (paramelts[i] == JvPrimClass (boolean))
	    COPY (&argvals[i],
		  ((java::lang::Boolean *) argelts[i])->booleanValue(),
		  jboolean);
	  else if (paramelts[i] == JvPrimClass (char))
	    COPY (&argvals[i],
		  ((java::lang::Character *) argelts[i])->charValue(),
		  jchar);
          else
	    {
	      java::lang::Number *num = (java::lang::Number *) argelts[i];
	      if (paramelts[i] == JvPrimClass (byte))
		COPY (&argvals[i], num->byteValue(), jbyte);
	      else if (paramelts[i] == JvPrimClass (short))
		COPY (&argvals[i], num->shortValue(), jshort);
	      else if (paramelts[i] == JvPrimClass (int))
		COPY (&argvals[i], num->intValue(), jint);
	      else if (paramelts[i] == JvPrimClass (long))
		COPY (&argvals[i], num->longValue(), jlong);
	      else if (paramelts[i] == JvPrimClass (float))
		COPY (&argvals[i], num->floatValue(), jfloat);
	      else if (paramelts[i] == JvPrimClass (double))
		COPY (&argvals[i], num->doubleValue(), jdouble);
	    }
	}
      else
	{
	  if (argelts[i] && ! paramelts[i]->isAssignableFrom (k))
	    throw new java::lang::IllegalArgumentException;
	  COPY (&argvals[i], argelts[i], jobject);
	}
    }

  jvalue ret_value;
  _Jv_CallAnyMethodA (obj, return_type, meth, is_constructor,
  		      _Jv_isVirtualMethod (meth),
		      parameter_types, argvals, &ret_value,
		      false, iface);

  jobject r;
#define VAL(Wrapper, Field)  (new Wrapper (ret_value.Field))
  if (is_constructor)
    r = ret_value.l;
  else  if (return_type == JvPrimClass (byte))
    r = VAL (java::lang::Byte, b);
  else if (return_type == JvPrimClass (short))
    r = VAL (java::lang::Short, s);
  else if (return_type == JvPrimClass (int))
    r = VAL (java::lang::Integer, i);
  else if (return_type == JvPrimClass (long))
    r = VAL (java::lang::Long, j);
  else if (return_type == JvPrimClass (float))
    r = VAL (java::lang::Float, f);
  else if (return_type == JvPrimClass (double))
    r = VAL (java::lang::Double, d);
  else if (return_type == JvPrimClass (boolean))
    r = VAL (java::lang::Boolean, z);
  else if (return_type == JvPrimClass (char))
    r = VAL (java::lang::Character, c);
  else if (return_type == JvPrimClass (void))
    r = NULL;
  else
    {
      JvAssert (return_type == NULL || ! return_type->isPrimitive());
      r = ret_value.l;
    }

  return r;
}