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

[Tobias Hartmann]

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
>>