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

[dean.long at oracle.com]

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.
>