[GR-75897] Reset aligned chunk pin count on initialization

PullRequest: graal/24191

Author: thomaswue

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/AlignedHeapChunk.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -86,6 +86,9 @@ public interface AlignedHeader extends HeapChunk.Header<AlignedHeader> {
         @RawField
         int getObjectPinCount();
 
+        @RawField
+        void setObjectPinCount(int value);
+
         @RawFieldAddress
         Pointer addressOfObjectPinCount();
 
@@ -101,6 +104,7 @@ public static void initialize(AlignedHeader chunk, UnsignedWord chunkSize) {
         assert chunk.isNonNull();
         assert chunkSize.equal(HeapParameters.getAlignedHeapChunkSize()) : "expecting all aligned chunks to be the same size";
         HeapChunk.initialize(chunk, AlignedHeapChunk.getObjectsStart(chunk), chunkSize);
+        chunk.setObjectPinCount(0);
         chunk.setSweep(false);
     }