RFR: 8356708: C2: loop strip mining expansion doesn't take sunk stores into account [v7]

[Roland Westrelin]

On Thu, 19 Jun 2025 09:59:49 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>>>     * Is this really something we want to put into JDK 25? Feels high-risk and it's and old issue after all. Maybe we can push this to JDK26 first, and backport a little later?
>> 
>> Either way is fine with me. It does feel like a nasty issue that wouldn't be easy to diagnose if someone runs into it in the wild.
>> 
>>>     * Is this really a regression from [JDK-8281322](https://bugs.openjdk.org/browse/JDK-8281322)? If not, the affects version in JBS should be updated such that we'll consider this for backporting.
>> 
>> I don't think it is. It's an issue that exists since loop strip mining exists AFAICT. I haven't tried how far back the test reproduces it though.
>
>> > ```
>> > * Is this really something we want to put into JDK 25? Feels high-risk and it's and old issue after all. Maybe we can push this to JDK26 first, and backport a little later?
>> > ```
>> 
>> Either way is fine with me. It does feel like a nasty issue that wouldn't be easy to diagnose if someone runs into it in the wild.
> 
> In my opinion, the fix is quite local and contained, so the risk of causing regressions does not seem too high. There is also still quite some time left to observe and react to issues before the RC phase. I would vote for JDK 25.

Thanks for the reviews @robcasloz @eme64

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PR Comment: https://git.openjdk.org/jdk/pull/25717#issuecomment-2991084448