RFR: 8303511: C2: assert(get_ctrl(n) == cle_out) during unrolling

[Vladimir Kozlov]

On Thu, 2 Mar 2023 09:24:17 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> In the same round of loop optimizations:
> 
> - `PhaseIdealLoop::remix_address_expressions()` creates a new `AddP`
>   out of loop. It sets it control to
>   `n_loop->_head->in(LoopNode::EntryControl)` which, because the loop is
>   strip mined, is an `OuterStripMinedLoop`.
>   
> - The `LoadI` for that `AddP` is found to only have uses outside the
>   loop and is cloned out of the loop. It's referenced by the outer
>   loop's safepoint.
>   
> - The loop is unrolled. Unrolling follows the safepoint's inputs and
>   find the new `AddP` with control set to the `OuterStripMinedLoop`
>   and the assert fires.
>   
> No control should be set to an `OuterStripMinedLoop`. The fix is
> straightforward and sets the control to the `OuterStripMinedLoop`
> entry control.

Yes, this looks good.

-------------

Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12824