Integrated: 8326638: Crash in PhaseIdealLoop::remix_address_expressions due to unexpected Region instead of Loop

[Tobias Hartmann]

On Mon, 26 Feb 2024 08:33:26 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> Adds a missing `_head->is_Loop()` check to handle the case when the loop head is not a `LoopNode` but a `RegionNode` because the loop is irreducible:
> 
> 
> (rr) p n_loop->_head->dump(1)
>   412 IfTrue === 411 [[ 345 ]] #1 !jvms: Test$Class1::Class1_method0 @ bci:286 (line 119)
>   339 SafePoint === 336 1 340 1 1 344 290 1 1 1 1 291 1 1 293 294 295 1 320 297 1 298 299 300 301 302 1 303 1 [[ 345 ]] SafePoint !jvms: Test$Class1::Class1_method0 @ bci:307 (line 122)
>   345 Region === 345 339 412 [[ 345 456 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 1861 1863 1865 1867 1882 1888 ]] #irreducible !jvms: Test$Class1::Class1_method0 @ bci:138 (line 101)
> 
> 
> We then crash when invoking `LoopNode::skip_strip_mined` on a RegionNode or assert in debug. Unfortunately, I was not able to simply the test any further.
> 
> This is a regression from [JDK-8303511](https://bugs.openjdk.org/browse/JDK-8303511) in JDK 21 b13
> 
> Thanks,
> Tobias

This pull request has now been integrated.

Changeset: 9f0e7da6
Author:    Tobias Hartmann <thartmann at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/9f0e7da64e21237322e55ca4f0e3639fa5d1c4ed
Stats:     60 lines in 2 files changed: 57 ins; 0 del; 3 mod

8326638: Crash in PhaseIdealLoop::remix_address_expressions due to unexpected Region instead of Loop

Reviewed-by: chagedorn, kvn

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PR: https://git.openjdk.org/jdk/pull/18002