Testing: code cache assumption.

Author: peter-hofer

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

@@ -31,7 +31,12 @@
 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.code.UntetheredCodeInfoAccess;
+import com.oracle.svm.core.genscavenge.compacting.ObjectMoveInfo;
 import com.oracle.svm.core.heap.ObjectReferenceVisitor;
+import com.oracle.svm.core.util.VMError;
+
+import jdk.graal.compiler.word.Word;
 
 /**
  * Before compaction, updates the same references that were visited by
@@ -54,6 +59,8 @@ public boolean visitCode(CodeInfo codeInfo) {
 
         int state = CodeInfoAccess.getState(codeInfo);
         if (state == CodeInfo.STATE_UNREACHABLE || state == CodeInfo.STATE_READY_FOR_INVALIDATION) {
+            Object tether = UntetheredCodeInfoAccess.getTetherUnsafe(codeInfo);
+            VMError.guarantee(tether != null && !isReachable(tether));
             /*
              * 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
@@ -68,4 +75,21 @@ public boolean visitCode(CodeInfo codeInfo) {
         RuntimeCodeInfoAccess.walkWeakReferences(codeInfo, visitor);
         return true;
     }
+
+    /**
+     * @return {code true} if the object will survive this collection, otherwise {@code false}.
+     */
+    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);