RFR: 8356647: C2: Excessively strict assert in PhaseIdealLoop::do_unroll

[Marc Chevalier]

On Wed, 21 May 2025 14:48:16 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> This assert seems a bit too tight. See the JBS issue to check the math: the bound of `trip_count` should be `<= 2^31`, while the current bound is ` < (julong)max_juint/2` = floor((2^32-1)/2) = (2^32-2) / 2 = 2^31-1.
>
> Drive-by comment: Were you able to extract a regression test that does not require the stress peeling flag?

Rather than the endlessly growing comment, I discussed with @chhagedorn and concluded to put asserts elsewhere to make more obvious and more unbreakable some invariants we rely on.

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PR Comment: https://git.openjdk.org/jdk/pull/25295#issuecomment-2911571432