[jdk16] RFR: 8259227: C2 crashes with SIGFPE due to a division that floats above its zero check

[Christian Hagedorn]

On Wed, 6 Jan 2021 18:11:55 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> This bug is very similar to [JDK-8257822](https://bugs.openjdk.java.net/browse/JDK-8257822). In this testcase, a `Div` node has no longer its zero check as direct control input and is later moved before the zero check by `IfNode::dominated_by()` which updates all data nodes to a dominating `If` (in JDK-8257822 it was done by `PhaseIdealLoop::dominated_by()`) .
>> 
>> I suggest to use the same fix for `IfNode::dominated_by()` as for `PhaseIdealLoop::dominated_by()` in JDK-8257822 to only move data nodes to the dominating `If` if it is not a `Div` or `Mod` node that could have a zero divisor (i.e. a zero check).
>> 
>> Thanks,
>> Christian
>
> Looks good.

Thanks for your review Vladimir!

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PR: https://git.openjdk.java.net/jdk16/pull/89