RFR: 8279508: Auto-vectorize Math.round API [v7]

[Jatin Bhateja]

On Thu, 24 Feb 2022 01:43:27 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8279508: Review comments resolved.
>
> src/hotspot/cpu/x86/macroAssembler_x86.cpp line 8984:
> 
>> 8982: }
>> 8983: 
>> 8984: void MacroAssembler::round_double(Register dst, XMMRegister src, Register rtmp, Register rcx) {
> 
> Is it possible to implement this using the similar mxcsr change? In any case comments will help to review round_double and round_float code.

LDMXCSR has multi-cycle latency and it will degrade the performance of scalar operation's fast path.

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PR: https://git.openjdk.java.net/jdk/pull/7094