Clear unused elements during transition from zero-based to contiguous array.

Author: woess

graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/runtime/array/dyn/AbstractWritableArray.java

@@ -838,6 +838,20 @@ public ScriptArray shiftRangeImpl(JSDynamicObject object, long from) {
         return removeRangeImpl(object, 0, from);
     }
 
+    protected static boolean unusedElementsAreHoles(Object[] array, int usedStart, int usedLength) {
+        for (int i = 0; i < usedStart; i++) {
+            if (array[i] != null) {
+                return false;
+            }
+        }
+        for (int i = usedStart + usedLength; i < array.length; i++) {
+            if (array[i] != null) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     protected interface SetSupportedProfileAccess extends ProfileAccess {
         default boolean ensureCapacityGrow(ProfileHolder profile, boolean condition) {
             return profile.profile(this, 0, condition);

graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/runtime/array/dyn/ContiguousJSObjectArray.java

@@ -52,6 +52,7 @@ public static ContiguousJSObjectArray makeContiguousJSObjectArray(JSDynamicObjec
                     int integrityLevel) {
         ContiguousJSObjectArray arrayType = createContiguousJSObjectArray().setIntegrityLevel(integrityLevel);
         setArrayProperties(object, array, length, usedLength, indexOffset, arrayOffset);
+        assert unusedElementsAreHoles(array, arrayOffset, usedLength);
         return arrayType;
     }
 

graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/runtime/array/dyn/ContiguousObjectArray.java

@@ -51,6 +51,7 @@ public final class ContiguousObjectArray extends AbstractContiguousObjectArray {
     public static ContiguousObjectArray makeContiguousObjectArray(JSDynamicObject object, long length, Object[] array, long indexOffset, int arrayOffset, int usedLength, int integrityLevel) {
         ContiguousObjectArray arrayType = createContiguousObjectArray().setIntegrityLevel(integrityLevel);
         setArrayProperties(object, array, length, usedLength, indexOffset, arrayOffset);
+        assert unusedElementsAreHoles(array, arrayOffset, usedLength);
         return arrayType;
     }
 

graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/runtime/array/dyn/ZeroBasedJSObjectArray.java

@@ -177,7 +177,9 @@ public ScriptArray removeRangeImpl(JSDynamicObject object, long start, long end)
     public ScriptArray shiftRangeImpl(JSDynamicObject object, long from) {
         int usedLength = getUsedLength(object);
         if (from < usedLength) {
-            return ContiguousJSObjectArray.makeContiguousJSObjectArray(object, lengthInt(object) - from, getArray(object), -from, (int) from, (int) (usedLength - from), integrityLevel);
+            JSDynamicObject[] array = getArray(object);
+            Arrays.fill(array, 0, (int) from, null);
+            return ContiguousJSObjectArray.makeContiguousJSObjectArray(object, lengthInt(object) - from, array, -from, (int) from, (int) (usedLength - from), integrityLevel);
         } else {
             return removeRangeImpl(object, 0, from);
         }

graal-js/src/com.oracle.truffle.js/src/com/oracle/truffle/js/runtime/array/dyn/ZeroBasedObjectArray.java

@@ -166,7 +166,9 @@ public ScriptArray removeRangeImpl(JSDynamicObject object, long start, long end)
     public ScriptArray shiftRangeImpl(JSDynamicObject object, long from) {
         int usedLength = getUsedLength(object);
         if (from < usedLength) {
-            return ContiguousObjectArray.makeContiguousObjectArray(object, lengthInt(object) - from, getArray(object), -from, (int) from, (int) (usedLength - from), integrityLevel);
+            Object[] array = getArray(object);
+            Arrays.fill(array, 0, (int) from, null);
+            return ContiguousObjectArray.makeContiguousObjectArray(object, lengthInt(object) - from, array, -from, (int) from, (int) (usedLength - from), integrityLevel);
         } else {
             return removeRangeImpl(object, 0, from);
         }