RFR: 8281429: PhiNode::Value() is too conservative for tripcount of CountedLoop [v7]

[Roland Westrelin]

On Fri, 29 Apr 2022 23:55:06 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> I am concern about unsigned arithmetic to calculate new limit for long indexing case. The test could simple fill up an array and you then check that values in it are correct (and no out of bounds references). You can choose big `stride` to run test fast.

The problem is this code:
https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/loopnode.cpp#L1762

It makes it impossible to construct a counted loop with limit Integer.MAX_VALUE with a big stride.

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PR: https://git.openjdk.java.net/jdk/pull/7823