To help debug floating point issues for JDK-6902692 the issue JDK-6898948 was used to add some instrumentation.
The instrumentation is guarded by a flag, which is false by default. So, unless the flag is enabled the instrumentation has no effect.
The patch to add the instrumentation is very small. I'll attach the patch to JDK-6902692 and remove the instrumentation from the code base. That way we have the instrumentation available if we ever start working on JDK-6902692 but we don't have to have the debugging code in our code base.