ConstantPoolObjectSlotIterator.cpp

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 * Copyright (c) 1991, 2019 IBM Corp. and others
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution and
 * is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following
 * Secondary Licenses when the conditions for such availability set
 * forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
 * General Public License, version 2 with the GNU Classpath
 * Exception [1] and GNU General Public License, version 2 with the
 * OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
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 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception
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/**
 * @file
 * @ingroup GC_Structs
 */

#include "j9.h"
#include "j9cfg.h"
#include "j9cp.h"
#include "ModronAssertions.h"

#include "ConstantPoolObjectSlotIterator.hpp"


/**
 * @return the next object slot in the constant pool
 * @return NULL if there are no more object references
 */
j9object_t *
GC_ConstantPoolObjectSlotIterator::nextSlot() {
	U_32 slotType;
	j9object_t *slotPtr;
	j9object_t *result = NULL;

	while (_cpEntryCount) {
		if (0 == _cpDescriptionIndex) {
			_cpDescription = *_cpDescriptionSlots;
			_cpDescriptionSlots += 1;
			_cpDescriptionIndex = J9_CP_DESCRIPTIONS_PER_U32;
		}

		slotType = _cpDescription & J9_CP_DESCRIPTION_MASK;
		slotPtr = _cpEntry;

		/* Determine if the slot should be processed */
		switch (slotType) {
		case J9CPTYPE_STRING: /* fall through */
		case J9CPTYPE_ANNOTATION_UTF8:
			result = &(((J9RAMStringRef *) slotPtr)->stringObject);
			break;
		case J9CPTYPE_METHOD_TYPE:
			result = &(((J9RAMMethodTypeRef *) slotPtr)->type);
			break;
		case J9CPTYPE_METHODHANDLE:
			result = &(((J9RAMMethodHandleRef *) slotPtr)->methodHandle);
			break;
		case J9CPTYPE_CONSTANT_DYNAMIC:
			if (NULL != (result = _constantDynamicSlotIterator.nextSlot(slotPtr))) {
				/* Do not progress through the function.
				 * Avoids advancing the slot while a constant dynamic is being iterated */
				return result;
			}
			break;
		default:
			break;
		}

		/* Adjust the CP slot and description information */
		_cpEntry = (j9object_t *) (((U_8 *) _cpEntry)
				+ sizeof(J9RAMConstantPoolItem));
		_cpEntryCount -= 1;

		_cpDescription >>= J9_CP_BITS_PER_DESCRIPTION;
		_cpDescriptionIndex -= 1;

		if (NULL != result) {
			break;
		}

	}
	return result;
}