RFR(S):8211251:Default mask register for avx512 instructions

[Viswanathan, Sandhya]

Hi Vladimir,

Please find the updated webrev with this change at:
http://cr.openjdk.java.net/~vdeshpande/k_register/webrev.01/

Best Regards,
Sandhya


-----Original Message-----
From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
Sent: Thursday, September 27, 2018 4:50 PM
To: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; hotspot compiler <hotspot-compiler-dev at openjdk.java.net>
Subject: Re: RFR(S):8211251:Default mask register for avx512 instructions

Use guarantee() instead of assert so if someone to try to use it with product JDK it will fail.

Thanks,
Vladimir

On 9/27/18 4:40 PM, Viswanathan, Sandhya wrote:
> Hi Vladimir,
> 
> As you know the PostLoopMultiversioning needs to be fully redesigned and is currently disabled.
> That particular code should only be exercised when PostLoopMultiversioning is on.
> I could change it with an assert statement if that looks ok to you.
> 
> Please let me know.
> 
> Best Regards,
> Sandhya
> 
> 
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com]
> Sent: Thursday, September 27, 2018 3:24 PM
> To: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; hotspot 
> compiler <hotspot-compiler-dev at openjdk.java.net>
> Subject: Re: RFR(S):8211251:Default mask register for avx512 
> instructions
> 
> Looks good except PostLoopMultiversioning flag guarded changes in 
> macroAssembler_x86.cpp which should be explained too.
> 
> Thanks,
> Vladimir
> 
> On 9/27/18 2:37 PM, Viswanathan, Sandhya wrote:
>> Please find below a patch which cleans up K1 mask register handling for AVX 512 instructions.
>>
>> Currently unmasked instructions are encoded using k1 register which 
>> requires k1 register to be initialized properly and also reinitialized across JNI and Runtime calls.
>>
>> This patch encodes AVX 512 instructions as unmasked instruction with 
>> K0 encoding where the explicit mask register is not specified.
>>
>> RFE: https://bugs.openjdk.java.net/browse/JDK-8211251
>>
>> Webrev: http://cr.openjdk.java.net/~vdeshpande/k_register/webrev.00/
>> <http://cr.openjdk.java.net/%7Evdeshpande/k_register/webrev.00/>
>>
>> Best Regards,
>>
>> Sandhya
>>