RFR: 8259430: C2: assert(in_vt->length() == out_vt->length()) failed: mismatch on number of elements

[Vladimir Ivanov]

On Thu, 11 Feb 2021 07:51:54 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Another problem caused by pathological cases (in effectively dead code): `VectorUnboxNode::Ideal()/Value()` ignore cast nodes (even the ones carrying control dependency) to reveal `VectorBox` and sometimes it exposes type mismatches between box/unbox operations which are impossible in practice. 
>> 
>> Proposed fix turns the assert into a runtime check to ignore problematic IR shape.
>
> Looks reasonable to me.

Thanks for the reviews, Vladimir and Tobias.

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PR: https://git.openjdk.java.net/jdk/pull/2353