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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package com.oracle.svm.core.genscavenge;

import com.oracle.svm.core.config.ConfigurationValues;
import com.oracle.svm.core.image.ImageHeap;
import com.oracle.svm.core.image.ImageHeapLayoutInfo;

public class LinearImageHeapLayouter extends AbstractImageHeapLayouter<LinearImageHeapPartition> {
    private final ImageHeapInfo heapInfo;
    private final long startOffset;
    private final boolean compressedNullPadding;

    public LinearImageHeapLayouter(ImageHeapInfo heapInfo, long startOffset, boolean compressedNullPadding) {
        this.heapInfo = heapInfo;
        this.startOffset = startOffset;
        this.compressedNullPadding = compressedNullPadding;
    }

    @Override
    protected LinearImageHeapPartition[] createPartitionsArray(int count) {
        return new LinearImageHeapPartition[count];
    }

    @Override
    protected LinearImageHeapPartition createPartition(String name, boolean containsReferences, boolean writable, boolean hugeObjects) {
        return new LinearImageHeapPartition(name, writable);
    }

    @Override
    protected ImageHeapLayoutInfo doLayout(ImageHeap imageHeap) {
        long beginOffset = startOffset;
        if (compressedNullPadding) {
            /*
             * Zero designates null, so adding some explicit padding at the beginning of the native
             * image heap is the easiest approach to make object offsets strictly greater than 0.
             */
            beginOffset += ConfigurationValues.getObjectLayout().getAlignment();
        }
        LinearImageHeapAllocator allocator = new LinearImageHeapAllocator(beginOffset);
        for (LinearImageHeapPartition partition : getPartitions()) {
            partition.allocateObjects(allocator);
        }
        initializeHeapInfo(imageHeap.countDynamicHubs());
        return createLayoutInfo(startOffset, getWritablePrimitive().getStartOffset());
    }

    
Store which objects are at the boundaries of the image heap partitions. Here, we also merge
the read-only reference partition with the read-only relocatable partition.
/**
     * Store which objects are at the boundaries of the image heap partitions. Here, we also merge
     * the read-only reference partition with the read-only relocatable partition.
     */
    private void initializeHeapInfo(int dynamicHubCount) {
        heapInfo.initialize(getReadOnlyPrimitive().firstObject, getReadOnlyPrimitive().lastObject, getReadOnlyReference().firstObject, getReadOnlyReference().lastObject,
                        getReadOnlyRelocatable().firstObject, getReadOnlyRelocatable().lastObject, getWritablePrimitive().firstObject, getWritablePrimitive().lastObject,
                        getWritableReference().firstObject, getWritableReference().lastObject, getWritableHuge().firstObject, getWritableHuge().lastObject,
                        getReadOnlyHuge().firstObject, getReadOnlyHuge().lastObject, ImageHeapInfo.NO_CHUNK, ImageHeapInfo.NO_CHUNK, dynamicHubCount);
    }
}