RFR: 8287227: Shenandoah: A couple of virtual thread tests failed with iu mode even without Loom enabled. [v2]

[Aleksey Shipilev]

On Fri, 3 Jun 2022 11:59:14 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> With JDK-8277654, the load barrier slow path call doesn't produce raw
>> memory anymore but the IU barrier call still does. I propose removing
>> raw memory for that call too which also causes the assert that fails
>> to be removed.
>
> Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:
> 
>  - new fix
>  - Merge branch 'master' into JDK-8287227
>  - Revert "fix"
>    
>    This reverts commit aa6f80a7883ee7032f81dbffac5d0257491d7118.
>  - fix

Looks good.

I tested `jdk_loom hotspot_loom` with Linux x86_64 fastdebug Shenandoah, including IU mode, and they pass. Apart from the known `Skynet` failure that is tracked separately.

Also ran Linux x86_64 fastdebug `tier1` with Shenandoah, with some unrelated failures.

src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp line 2678:

> 2676: void MemoryGraphFixer::record_new_ctrl(Node* ctrl, Node* new_ctrl, Node* mem, Node* mem_for_ctrl) {
> 2677:   if (mem_for_ctrl != mem) {
> 2678:     if (new_ctrl != ctrl) {

This two branches look collapsible.

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.org/jdk/pull/8958