[11] RFR(XS) 8209735: Disable avx512 by default

[Vladimir Kozlov]

Thank you, Dean

Unfortunately I pushed it already and can't list you as reviewer.

Vladimir

On 8/20/18 3:06 PM, dean.long at oracle.com wrote:
> Looks good.
> 
> dl
> 
> On 8/20/18 10:50 AM, Vladimir Kozlov wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8209735
>>
>> I found several issues with avx512 code. Some are listed in bug report.
>> At this later time I suggest to switch off avx512 in JDK 11:
>>
>> diff -r 7339b9e38182 src/hotspot/cpu/x86/globals_x86.hpp
>> --- a/src/hotspot/cpu/x86/globals_x86.hpp
>> +++ b/src/hotspot/cpu/x86/globals_x86.hpp
>> @@ -119,7 +119,7 @@
>>    product(bool, UseStoreImmI16, true,                                       \
>>            "Use store immediate 16-bits value instruction on x86")           \
>> \
>> -  product(intx, UseAVX, 3,                                                  \
>> +  product(intx, UseAVX, 2,                                                  \
>>            "Highest supported AVX instructions set on x86/x64")              \
>>            range(0, 99)                                                      \
>>
>> Tested tier1,hs-tier2.
>>
>