[jdk21u-dev] RFR: 8318049: C2: assert(!failure) failed: Missed optimization opportunity in PhaseIterGVN

[Goetz Lindenmaier]

On Thu, 6 Mar 2025 07:19:19 GMT, Yude Lin <linade at openjdk.org> wrote:

> Hi,
> 
> I'd like to backport 8318049 as part of a fix for a test. Thanks.

Hi,
registering new nodes to an optimization offers new graph patterns to the optimization. It is completely unknown whether the optimization will handle this correctly. It might generate new patterns a later optimization fails to handle. 
It might cause code size changes that have weird effects to well running applications. I would rate the risk at least medium.  
What are your experiences with compiler optimizations?
If you only saw the problem in a test, I don't think it's worth while to take the risk.

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PR Comment: https://git.openjdk.org/jdk21u-dev/pull/1454#issuecomment-2716985823