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

[Eric Caspole]

Hi Vladimir,
Looks good.
Eric


On 08/20/2018 01:50 PM, 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.
>