RFR(XS): https://bugs.openjdk.java.net/browse/JDK-8240840

[Yumin Qi]

Hi,
   I just pushed 8240691: 
https://bugs.openjdk.java.net/browse/JDK-8240691 but wrongly included 
changes in whitbox.cpp which should not change in this bug. Instead it 
is for bug 8240563.

--- a/src/hotspot/share/prims/whitebox.cpp    Tue Mar 10 20:51:09 2020 +0300
+++ b/src/hotspot/share/prims/whitebox.cpp    Tue Mar 10 11:52:53 2020 -0700
@@ -1990,12 +1990,6 @@

  WB_ENTRY(jboolean, WB_IsCDSIncludedInVmBuild(JNIEnv* env))
  #if INCLUDE_CDS
-# ifdef _LP64
-    if (!UseCompressedOops || !UseCompressedClassPointers) {
-      // On 64-bit VMs, CDS is supported only with compressed oops/pointers
-      return false;
-    }
-# endif // _LP64
    return true;
  #else
    return false;

Now I need add it back since it will fail other two test cases:
test/hotspot/jtreg/runtime/cds/appcds/CommandLineFlagComboNegative.java
test/hotspot/jtreg/runtime/cds/appcds/TestZGCWithCDS.java

The diff for roll back is:
  WB_ENTRY(jboolean, WB_IsCDSIncludedInVmBuild(JNIEnv* env))
  #if INCLUDE_CDS
+# ifdef _LP64
+    if (!UseCompressedOops || !UseCompressedClassPointers) {
+      // On 64-bit VMs, CDS is supported only with compressed oops/pointers
+      return false;
+    }
+# endif // _LP64
    return true;
  #else
    return false;

Seek approval for this accidental change.

Thanks
Yumin