[aarch64] assert(is_power_of_2(x)) failed: x must be a power of 2: 0xffffffff80000000

[Doerr, Martin]

Hi arm64 folks,

I've created an issue:
https://bugs.openjdk.java.net/browse/JDK-8239861

Failues were observed in e.g. jck tests api/java_awt/Font/LineBreakMeasurer.

Best regards,
Martin