--- a/graal/com.oracle.graal.hotspot.test/src/com/oracle/graal/hotspot/test/ClassSubstitutionsTests.java	Mon Nov 24 11:40:00 2014 -0800
+++ b/graal/com.oracle.graal.hotspot.test/src/com/oracle/graal/hotspot/test/ClassSubstitutionsTests.java	Mon Nov 24 11:48:24 2014 -0800
@@ -108,11 +108,10 @@
     }
 
     @Test
-    public void testFoldComponenetType() {
+    public void testFoldComponentType() {
         testConstantReturn("foldComponentType", 1);
     }
 
-    @Ignore("Can't constant fold LoadHubNode == 0 yet")
     @Test
     public void testFieldIsArray() {
         testConstantReturn("fieldIsArray", 1);

--- a/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/nodes/type/KlassPointerStamp.java	Mon Nov 24 11:40:00 2014 -0800
+++ b/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/nodes/type/KlassPointerStamp.java	Mon Nov 24 11:48:24 2014 -0800
@@ -32,14 +32,20 @@
 
 public final class KlassPointerStamp extends MetaspacePointerStamp {
 
+    private static final KlassPointerStamp KLASS = new KlassPointerStamp(false, false);
+
+    private static final KlassPointerStamp KLASS_NON_NULL = new KlassPointerStamp(true, false);
+
+    private static final KlassPointerStamp KLASS_ALWAYS_NULL = new KlassPointerStamp(false, true);
+
     private final CompressEncoding encoding;
 
     public static KlassPointerStamp klass() {
-        return new KlassPointerStamp(false, false, null);
+        return KLASS;
     }
 
     public static KlassPointerStamp klassNonNull() {
-        return new KlassPointerStamp(true, false, null);
+        return KLASS_NON_NULL;
     }
 
     private KlassPointerStamp(boolean nonNull, boolean alwaysNull) {
@@ -71,12 +77,19 @@
             }
         } else {
             if (JavaConstant.NULL_POINTER.equals(c)) {
-                return new KlassPointerStamp(false, true);
+                return KLASS_ALWAYS_NULL;
             }
         }
 
         assert c instanceof HotSpotMetaspaceConstant;
-        return this;
+        if (nonNull()) {
+            return this;
+        }
+        if (isCompressed()) {
+            return new KlassPointerStamp(true, false, encoding);
+        } else {
+            return KLASS_NON_NULL;
+        }
     }
 
     @Override

--- a/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/replacements/KlassLayoutHelperNode.java	Mon Nov 24 11:40:00 2014 -0800
+++ b/graal/com.oracle.graal.hotspot/src/com/oracle/graal/hotspot/replacements/KlassLayoutHelperNode.java	Mon Nov 24 11:48:24 2014 -0800
@@ -93,8 +93,7 @@
             return null;
         } else {
             if (klass.isConstant()) {
-                long base = klass.asJavaConstant().asLong();
-                if (base != 0L) {
+                if (!klass.asConstant().isDefaultForKind()) {
                     Constant constant = stamp().readConstant(tool.getConstantReflection().getMemoryAccessProvider(), klass.asJavaConstant(), runtime().getConfig().klassLayoutHelperOffset);
                     return ConstantNode.forConstant(stamp(), constant, tool.getMetaAccess());
                 }