[lilliput-jdk17u:lilliput] RFR: 8300566: [Lilliput/JDK17] Properly set ZF on anon-check path

[Aleksey Shipilev]

On Wed, 18 Jan 2023 16:07:01 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> In AArch64's fast_unlock(), we need to check if the monitor owner is ANONYMOUS (only with Lilliput/fast-locking), and if so, call the runtime to fix this before exiting the monitor. I tried to be smart and used tbnz there, but it turns out that tbnz does *not* set the zero flag, but we do need the ZF set correctly on exit of fast_unlock, so that C2 generated code would actually call the slow path. Therefore we need to use the longer tst/br instructions instead.

Marked as reviewed by shade (Reviewer).

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PR: https://git.openjdk.org/lilliput-jdk17u/pull/4