[10] RFR(XS): 8194494: SHA-512 stub uses AVX 2 instructions on non-supporting CPUs

[Tobias Hartmann]

Thanks Vladimir!

Best regards,
Tobias

On 04.01.2018 18:11, Vladimir Kozlov wrote:
> Good.
> 
> Thanks,
> Vladimir
> 
> On 1/3/18 11:35 PM, Tobias Hartmann wrote:
>> Hi Vladimir,
>>
>> On 03.01.2018 20:44, Vladimir Kozlov wrote:
>>> Even so sha512 is only implemented for 64-bit I think you should not restrict check with LP64_ONLY(). The only
>>> implementation uses avx2.
>>
>> Okay, that makes sense. Here's the new webrev:
>> http://cr.openjdk.java.net/~thartmann/8194494/webrev.01/
>>
>> Thanks,
>> Tobias
>>
>>
>>> On 1/3/18 8:49 AM, Tobias Hartmann wrote:
>>>> Hi,
>>>>
>>>> please review the following patch:
>>>> https://bugs.openjdk.java.net/browse/JDK-8194494
>>>> http://cr.openjdk.java.net/~thartmann/8194494/webrev.00/
>>>>
>>>> The VM crashes with SIGILL on CPUs that have the SHA extension but no AVX 2 support because since JDK-8165381 the
>>>> SHA-512 stub uses AVX 2 instructions (for example, 'vpblendd'). In addition to UseSHA, we need to check for
>>>> supports_avx2() && supports_bmi2() on x86.
>>>>
>>>> I had no suitable machine available for testing but I was able to trigger the problem by enforcing
>>>> UseSHA512Intrinsics=true on my machine and disabling AVX 2 support (see comments in the bug for details).
>>>>
>>>> This problem was reported by Csaba Mate [1].
>>>>
>>>> Thanks,
>>>> Tobias
>>>>
>>>> [1] http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2018-January/028002.html
>>>>