fixup! Revisit newly added files.

Author: peter-hofer

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

@@ -31,18 +31,19 @@
 import com.oracle.svm.core.code.CodeInfoAccess;
 import com.oracle.svm.core.code.RuntimeCodeCache.CodeInfoVisitor;
 import com.oracle.svm.core.code.RuntimeCodeInfoAccess;
-import com.oracle.svm.core.heap.ObjectReferenceVisitor;
+import com.oracle.svm.core.code.UntetheredCodeInfoAccess;
+import com.oracle.svm.core.genscavenge.compacting.ObjectMoveInfo;
+import com.oracle.svm.core.genscavenge.compacting.ObjectRefFixupVisitor;
 
-/**
- * Before compaction, updates the same references that were visited by
- * {@link RuntimeCodeCacheWalker} during the mark phase.
- */
+import jdk.graal.compiler.word.Word;
+
+/** Before compaction, updates references from {@link CodeInfo} structures. */
 final class RuntimeCodeCacheFixupWalker implements CodeInfoVisitor {
 
-    private final ObjectReferenceVisitor visitor;
+    private final ObjectRefFixupVisitor visitor;
 
     @Platforms(Platform.HOSTED_ONLY.class)
-    RuntimeCodeCacheFixupWalker(ObjectReferenceVisitor visitor) {
+    RuntimeCodeCacheFixupWalker(ObjectRefFixupVisitor visitor) {
         this.visitor = visitor;
     }
 
@@ -54,18 +55,33 @@ public boolean visitCode(CodeInfo codeInfo) {
 
         int state = CodeInfoAccess.getState(codeInfo);
         if (state == CodeInfo.STATE_UNREACHABLE || state == CodeInfo.STATE_READY_FOR_INVALIDATION) {
-            /*
-             * The code will be freed during this collection, but we need to make sure that all the
-             * objects that are accessed during the invalidation remain accessible. Those objects
-             * can only be collected in a subsequent garbage collection.
-             */
-            RuntimeCodeInfoAccess.walkObjectFields(codeInfo, visitor);
-            return true;
+            Object tether = UntetheredCodeInfoAccess.getTetherUnsafe(codeInfo);
+            if (tether != null && !isReachable(tether)) {
+                /*
+                 * The CodeInfo's state was changed to unreachable or to-be-invalidated during the
+                 * mark phase, so we only need to visit references that will be accessed before the
+                 * unmanaged memory is freed.
+                 */
+                RuntimeCodeInfoAccess.walkObjectFields(codeInfo, visitor);
+                return true;
+            }
         }
 
         /* The CodeInfo remains valid, so we need to fix up all references. */
         RuntimeCodeInfoAccess.walkStrongReferences(codeInfo, visitor);
         RuntimeCodeInfoAccess.walkWeakReferences(codeInfo, visitor);
         return true;
     }
+
+    public static boolean isReachable(Object tether) {
+        if (HeapImpl.getHeapImpl().isInImageHeap(tether)) {
+            return true;
+        }
+        Space space = HeapChunk.getSpace(HeapChunk.getEnclosingHeapChunk(tether));
+        if (space == null || !space.isOldSpace()) {
+            return false;
+        }
+        Word ptr = Word.objectToUntrackedPointer(tether);
+        return ObjectMoveInfo.getNewObjectAddress(ptr).isNonNull();
+    }
 }

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/compacting/ObjectMoveInfo.java

@@ -181,7 +181,7 @@ public static void walkObjects(AlignedHeapChunk.AlignedHeader chunkHeader, Objec
     }
 
     @Uninterruptible(reason = CALLED_FROM_UNINTERRUPTIBLE_CODE, mayBeInlined = true)
-    static Pointer getNewObjectAddress(Pointer objPointer) {
+    public static Pointer getNewObjectAddress(Pointer objPointer) {
         assert ObjectHeaderImpl.isAlignedObject(objPointer.toObject());
 
         AlignedHeapChunk.AlignedHeader chunk = AlignedHeapChunk.getEnclosingChunkFromObjectPointer(objPointer);