I got a test failure locally in both TestInstanceKlassSize and TestInstanceKlassSizeForInstance. When investigating the latter I noticed that we're actually not running TestInstanceKlassSizeForInstance due incorrect jtreg @run:

diff -r 1b2adb73f629 test/hotspot/jtreg/serviceability/sa/TestInstanceKlassSizeForInterface.java
--- a/test/hotspot/jtreg/serviceability/sa/TestInstanceKlassSizeForInterface.java Sat Jan 18 00:07:38 2020 +0100
+++ b/test/hotspot/jtreg/serviceability/sa/TestInstanceKlassSizeForInterface.java Sat Jan 18 14:53:10 2020 +0100
@@ -49,7 +49,7 @@
  * jdk.hotspot.agent/sun.jvm.hotspot.debugger
  * @build sun.hotspot.WhiteBox
  * @run driver ClassFileInstaller sun.hotspot.WhiteBox sun.hotspot.WhiteBox$WhiteBoxPermission
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:. TestInstanceKlassSize
+ * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xbootclasspath/a:. TestInstanceKlassSizeForInterface
  */
 
 import sun.hotspot.WhiteBox;