RFR: 8340141: C1: rework ciMethod::equals following 8338471

[Dean Long]

On Tue, 24 Sep 2024 00:35:47 GMT, Dean Long <dlong at openjdk.org> wrote:

> This PR changes ciMethod::equals() to a special-purpose debug helper method for the one place in C1 that uses it in an assert.  The reason why making it general purpose is difficult is because JVMTI can add and delete methods.   See the bug report and JDK-8338471 for more details.  I'm open to suggestions for a better name than equals_ignore_version().
> 
> An alternative approach, which I think may actually be better, would be to check for old methods first, and bail out if we see any.  Then we can change the assert back to how it was originally, using ==.

The alternative approach would look something like this:

    if (target->get_Method()->is_old() || cha_monomorphic_target->get_Method()->is_old()) {
        BAILOUT("redefined method");
    }
    assert(!target->can_be_statically_bound() || target == cha_monomorphic_target, "");

@coleenp, @matias9927, please take a look at this PR too.

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PR Comment: https://git.openjdk.org/jdk/pull/21148#issuecomment-2372675815
PR Comment: https://git.openjdk.org/jdk/pull/21148#issuecomment-2372676983