RFR: 8279508: Auto-vectorize Math.round API [v15]

[Quan Anh Mai]

On Sat, 12 Mar 2022 23:22:16 GMT, Quan Anh Mai <duke at openjdk.java.net> wrote:

>> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8279508: Creating separate test for round double under feature check.
>
> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4161:
> 
>> 4159:   movl(scratch, 1056964608);
>> 4160:   movq(xtmp1, scratch);
>> 4161:   vbroadcastss(xtmp1, xtmp1, vec_enc);
> 
> An `evpbroadcastd` would reduce this by one instruction I guess?

Anyway an `evpbroadcastd xmm, r` has around 5 latency on the gpr so I think you could just put the constant in the constant table and use `vbroadcastsd`

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