RFR: 8267928: Loop predicate gets inexact loop limit before PhaseIdealLoop::rc_predicate

[Yi Yang]

On Fri, 28 May 2021 13:29:36 GMT, Yi Yang <yyang at openjdk.org> wrote:

> Loop predicate gets inexact loop limit(LoopLimitNode) from exact_limit(even if the limit is statically known) and does unnecessary overflow checking when generating lower bound test(rc_predicate). The reason is rather straightforward: exact_limit fails to see a HasExactTripCount flag since it would be set after performing loop predicate(iteration_split).

Yes, I'll prepare an IR test for it.

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PR: https://git.openjdk.java.net/jdk/pull/4247