RFR(XS): JDK-8207746: C2: Lucene crashes on AVX512 instruction: Fix

[Vladimir Kozlov]

Thank you very much, Vivek, for your hard work to find the issue and fixing it.

The fix totally makes sense. I will run all our test with it.

Meanwhile can you check other places (intrinsics) where we operate on stack pointer to make sure 
that they don't have the same issue? It is not urgent and separate issue but I am now concern about 
how we use it in code.

Thanks,
Vladimir

On 8/14/18 10:37 AM, Deshpande, Vivek R wrote:
> Hi All
> 
> I have a patch for the fix for Lucene crash using AVX512.
> 
> You can find the webrev at this location:
> 
> http://cr.openjdk.java.net/~vdeshpande/Lucene_avx512/webrev.00/
> 
> Could you please review the change.
> 
> The EFLAGS register was getting clobbered, causing the result of vptest instruction getting 
> clobbered, leading to crash.
> 
> This fix avoids the clobbering of the result of the vptest instruction.
> 
> I tested the fix with elastic-search docker container on skylake server. The container is running 
> for more than 18 hours now.
> 
> Regards,
> 
> Vivek
>