Add diagnostic flag to tests.

Author: Arraying

test/hotspot/jtreg/runtime/valhalla/inlinetypes/UnsafeTest.java

@@ -36,7 +36,9 @@
  * @enablePreview
  * @requires vm.flagless
  * @compile Point.java UnsafeTest.java
- * @run main/othervm -Xint -XX:+UseNullableValueFlattening -XX:+UseArrayFlattening -XX:+UseFieldFlattening -XX:+PrintInlineLayout runtime.valhalla.inlinetypes.UnsafeTest
+ * @run main/othervm -Xint -XX:+UnlockDiagnosticVMOptions
+                     -XX:+UseNullableValueFlattening -XX:+UseArrayFlattening -XX:+UseFieldFlattening
+                     -XX:+PrintInlineLayout runtime.valhalla.inlinetypes.UnsafeTest
  */
 
 // TODO 8350865 Implement unsafe intrinsics for nullable flat fields/arrays in C2

test/hotspot/jtreg/serviceability/jvmti/valhalla/HeapDump/HeapDump.java

@@ -150,7 +150,8 @@ public static void main(String[] args) throws Throwable {
             theApp = new HeapDumpTarg();
 
             // -XX:+PrintInlineLayout is debug-only arg
-            LingeredApp.startApp(theApp, "--enable-preview", "-XX:+PrintInlineLayout", "-XX:+PrintFlatArrayLayout",
+            LingeredApp.startApp(theApp, "--enable-preview", "-XX:+UnlockDiagnosticVMOptions",
+                                "-XX:+PrintInlineLayout", "-XX:+PrintFlatArrayLayout",
                                  "--add-modules=java.base",
                                  "--add-exports=java.base/jdk.internal.value=ALL-UNNAMED");