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

[Christian Hagedorn]

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).

Looks good to me.

About the IR test, I think it's a good idea to add such a test. There is currently an ongoing discussion where to put IR tests in the future:
https://github.com/openjdk/jdk/pull/5135#discussion_r690530417

Maybe you can hold off integrating this change until a decision is made and then change the location of your IR test accordingly.

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Marked as reviewed by chagedorn (Reviewer).

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