RFR: 8261308: C2: assert(inner->is_valid_counted_loop(T_INT) && inner->is_strip_mined()) failed: OuterStripMinedLoop should have been removed

[Roland Westrelin]

On Wed, 24 Feb 2021 19:43:14 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> Add comment here explaining this case (one trip when init >= limit).

Ok. Do you still think we need extra tests?

> BTW, this optimization seems only works for INT iv loops and not LONG. Do you plan to implement for LONG?

I thought about it but it's not straightforward because the current code uses long to avoid overflow. I would also like to rework the parallel iv code so it works with LONG loops. I don't have time right now, thought.

Note also, that because of the iv phi Value(), I would expect some of the single iteration loops to be optimized even without a working IdealLoopTree::compute_trip_count(). That would be true for in and long loops.

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PR: https://git.openjdk.java.net/jdk/pull/2529