RFR: 8361702: C2: assert(is_dominator(compute_early_ctrl(limit, limit_ctrl), pre_end)) failed: node pinned on loop exit test? [v9]

[Emanuel Peter]

On Mon, 15 Sep 2025 14:25:02 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> A node in a pre loop only has uses out of the loop dominated by the
>> loop exit. `PhaseIdealLoop::try_sink_out_of_loop()` sets its control
>> to the loop exit projection. A range check in the main loop has this
>> node as input (through a chain of some other nodes). Range check
>> elimination needs to update the exit condition of the pre loop with an
>> expression that depends on the node pinned on its exit: that's
>> impossible and the assert fires. This is a variant of 8314024 (this
>> one was for a node with uses out of the pre loop on multiple paths). I
>> propose the same fix: leave the node with control in the pre loop in
>> this case.
>
> Roland Westrelin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   review

Yes, thanks for the updates 😊

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Marked as reviewed by epeter (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26424#pullrequestreview-3225140490