The fix for JDK-8247697 removed all usages of 'delayed_forbidden' because it was always false in mainline. In Valhalla, it's still used and removing it causes problems with method handle optimizations.

I've traced it back to this change from [~roland]:
http://hg.openjdk.java.net/valhalla/valhalla10-old/hotspot/rev/4cd1b06ce224
http://cr.openjdk.java.net/~roland/valhalla/returnconvention/webrev.01/

"I also improved handling of AlwaysIncrementalInline by C2 so its behavior is closer to the non incremental inline case. As a consequence I removed some of the special case match rules for AlwaysIncrementalInline."
http://mail.openjdk.java.net/pipermail/valhalla-dev/2017-May/002464.html

We should re-evaluate if these changes are needed.