[aarch64-port-dev ] RFR: Backport 8219006: AArch64: Register corruption in slow subtype check

[Andrew Haley]

http://cr.openjdk.java.net/~aph/8219006-jdk8u/

Almost unchanged: the files have moved, and one hunk had to be fixed
by hand, but it's the same patch. We need this because Amazon detected
a crash in testing. Smoke tested, bootstrapped.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
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