RFR: 8264649: runtime/InternalApi/ThreadCpuTimesDeadlock.java crash in fastdebug C2 with -XX:-UseTLAB

[Tobias Hartmann]

On Sat, 3 Apr 2021 00:53:54 GMT, Hui Shi <hshi at openjdk.org> wrote:

> Please help review this fix. Detailed analysis in https://bugs.openjdk.java.net/browse/JDK-8264649
> 
> Tier1/2 release /fastdebug passed

Changes requested by thartmann (Reviewer).

src/hotspot/share/opto/phaseX.cpp line 1481:

> 1479:   // Smash all inputs to 'old', isolating him completely
> 1480:   Node *temp = new Node(1);
> 1481:   temp->init_req(0,nn);     // Add a use to nn to prevent him from dying

Just wondering, why do we even need this? Without that code, `remove_dead_node(old)` would kill `nn` as well if it becomes dead.

test/hotspot/jtreg/runtime/InternalApi/ThreadCpuTimesDeadlock.java line 36:

> 34:  * @test
> 35:  * @bug 8264649
> 36:  * @summary OSR compiled metthod crash when UseTLAB is off

Typo `metthod`.

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PR: https://git.openjdk.java.net/jdk/pull/3336