Memory Corruption in JDK-21 on x86_64 with AVX-512

[Vladimir Kozlov]

https://bugs.openjdk.org/browse/JDK-8317121

On 9/27/23 11:19 AM, Vladimir Kozlov wrote:
> Officially jdk21.0.1 is closed for fixes but we are discussing this 
> issue now.
> 
> I verified the suggested by Xiaohong fix:
> retrun nullptr in StoreVectorNode::Ideal() and LoadVectorNode::Ideal().
> 
> I will file a bug and follow the process.
> 
> Regards,
> Vladimir K
> 
> On 9/27/23 9:54 AM, Viswanathan, Sandhya wrote:
>> Copying Tobias.
>>
>>  From what I see JDK21 update schedule has a mid-October release plan 
>> (https://wiki.openjdk.org/display/JDKUpdates/JDK+21u).
>>
>> Tobias, do you know the code freeze date for that. Hopefully, we still 
>> have a couple of days left.
>>
>> At the minimum we should revert to return nullptr in both 
>> LoadVectorMaskedNode::Ideal and StoreVectorMaskedNode::Ideal as a 
>> workaround.
>>
>> Best Regards,
>> Sandhya
>>
>> -----Original Message-----
>> From: hotspot-compiler-dev <hotspot-compiler-dev-retn at openjdk.org> On 
>> Behalf Of Carter Kozak
>> Sent: Wednesday, September 27, 2023 7:26 AM
>> To: Xiaohong Gong <Xiaohong.Gong at arm.com>; 
>> hotspot-compiler-dev at openjdk.org
>> Subject: Re: Memory Corruption in JDK-21 on x86_64 with AVX-512
>>
>> Thank you for such a quick diagnosis, I really appreciate it!
>>
>> While I don't have a good sense of the mapping between bug severity 
>> and backport/release criteria, I suspect this issue may be a strong 
>> candidate for an out-of-band jdk-21 release. I'm certainly biased 
>> because I had invalid bytes silently persisted, and defer to folks 
>> closer to the process.
>>
>> Best,
>> Carter Kozak
>>
>> On Wed, Sep 27, 2023, at 02:57, Xiaohong Gong wrote:
>>> Hi Carter,
>>> Thanks for reporting this issue!
>>> It seems the issue is caused by the calling of the super class’s 
>>> “Ideal()” method in “LoadVectorMaskedNode::Ideal()” (code is: 
>>> 8286941: Add mask IR for partial vector operations for ARM SVE by 
>>> XiaohongGong · Pull Request #9037 · openjdk/jdk (github.com) 
>>> <https://github.com/openjdk/jdk/pull/9037/files#diff-692826251cae892bc4737919579c6afbd317551cd507f99c7bd29d585c1282e2R1028>).
>>> Some optimization applied on “LoadNode” is not suitable for 
>>> “LoadVectorMaskedNode” now. Reverting it back to “return nullptr” can 
>>> make your benchmark pass.
>>> I will look at this issue and try to fix it next. Thanks!