RFR: 8332032: C2: Remove ExpandSubTypeCheckAtParseTime flag

[Christian Hagedorn]

On Mon, 13 May 2024 00:59:18 GMT, xiaotaonan <duke at openjdk.org> wrote:

>> C2: Remove ExpandSubTypeCheckAtParseTime flag
>
> @lgxbslgx

Hi @xiaotaonan, please first ask in JBS if you can take over RFEs/bugs that are already assigned like this one, especially if it has just been filed. This PR misses the entire context why this flag should be removed and what the pros/cons and trade-offs are. I planned to do some more offline discussions first before proposing the actual PR to remove this flag since it is now related to an otherwise hard-to-fix bug in Valhalla.

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PR Comment: https://git.openjdk.org/jdk/pull/19205#issuecomment-2106694300