RFR: 8240772: x86_64: Pre-generate Assembler::popa, pusha and vzeroupper

[Claes Redestad]

On 2020-03-11 19:29, Vladimir Kozlov wrote:
> 
> That leads to question. Claes, what was the reason you used loop instead 
> of memcpy for vzeroupper?

For UseAXV <= 2 then vzeroupper is 3 bytes, so the loop simply used
fewer instructions. It doesn't seem to matter much in the end, so let's
favor simplicity.

Final(?) version: http://cr.openjdk.java.net/~redestad/8240772/open.02/

/Claes