RFR: 8316361: C2: assert(!failure) failed: Missed optimization opportunity in PhaseIterGVN with -XX:VerifyIterativeGVN=10

[Emanuel Peter]

On Fri, 22 Sep 2023 18:03:14 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> This seems to be related to [JDK-8298176](https://bugs.openjdk.org/browse/JDK-8298176) / https://github.com/openjdk/jdk20/pull/65
>> This change allows `OpaqueZeroTripGuard -> CmpI` to fold in some cases. We have also added code to notify the `CmpI` during IGVN, so it can potentially change its type/constant fold:
>> https://github.com/openjdk/jdk/blob/a0a09d56ba4fc6133b423ad29d86fc99dd6dc19b/src/hotspot/share/opto/phaseX.cpp#L1681-L1687
>> 
>> However, when we hack the input to the `opaq` node, we must call `_igvn.add_users_to_worklist` to trigger this notification. I added this missing part.
>> 
>> Running Tier1-6 and stress testing...
>
> Good.

Thanks for the reviews @vnkozlov @chhagedorn !

-------------

PR Comment: https://git.openjdk.org/jdk/pull/15886#issuecomment-1742557797