RFR(S) 8209651: better TLS poll for x64 C2

[dean.long at oracle.com]

Thanks Vladimir.

dl

On 8/21/18 6:11 PM, Vladimir Kozlov wrote:
> Looks good.
>
> Thanks,
> Vladimir
>
> On 8/21/18 1:18 PM, dean.long at oracle.com wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8209651
>> http://cr.openjdk.java.net/~dlong/8209651/webrev/
>>
>> This change allows C2 to use any available register when doing a 
>> thread-local GC poll.
>>
>> dl
>>