[lworld] RFR: 8280524: [lworld] Interpreter incorrectly handles uninitialized static inline type field

[Tobias Hartmann]

On Tue, 25 Jan 2022 10:57:57 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> Code in the interpreter that's supposed to check if the type of a static, null-free inline type field is initialized assumes that `rcx` contains the `InlineKlass*`. However, `rcx` is only initialized for non-static fields:
> https://github.com/openjdk/valhalla/blob/ba87b167f2fe2327508a06ec8652c6ddaa9402c1/src/hotspot/cpu/x86/templateTable_x86.cpp#L2939-L2943
> 
> As a result, the check spuriously fails, leading to an "impossible" NPE because the null value is not replaced by the default value. This patch also fixes an unrelated issue where an `instanceHandle` should be used instead of an `instanceOop`.
> 
> I found this with compiler stress testing and initially assumed that it is a compiler bug. The patch was contributed by @fparain.
> 
> Thanks,
> Tobias

Thanks, Fred!

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PR: https://git.openjdk.java.net/valhalla/pull/617