RFR: 8279508: Auto-vectorize Math.round API [v6]

[Sandhya Viswanathan]

On Thu, 17 Feb 2022 17:43:43 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Summary of changes:
>> - Intrinsify Math.round(float) and Math.round(double) APIs.
>> - Extend auto-vectorizer to infer vector operations on encountering scalar IR nodes for above intrinsics.
>> - Test creation using new IR testing framework.
>> 
>> Following are the performance number of a JMH micro included with the patch 
>> 
>> Test System: Intel(R) Xeon(R) Platinum 8380 CPU @ 2.30GHz (Icelake Server)
>> 
>> 
>> TESTSIZE | Baseline AVX3 (ops/ms) | Withopt AVX3 (ops/ms) | Gain ratio | Baseline AVX2 (ops/ms) | Withopt AVX2 (ops/ms) | Gain ratio
>> -- | -- | -- | -- | -- | -- | --
>> 1024.00 | 510.41 | 1811.66 | 3.55 | 510.40 | 502.65 | 0.98
>> 2048.00 | 293.52 | 984.37 | 3.35 | 304.96 | 177.88 | 0.58
>> 1024.00 | 825.94 | 3387.64 | 4.10 | 750.77 | 1925.15 | 2.56
>> 2048.00 | 411.91 | 1942.87 | 4.72 | 412.22 | 1034.13 | 2.51
>> 
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8279508: Fixing for windows failure.

src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4146:

> 4144:   vaddpd(xtmp1, src , xtmp1, vec_enc);
> 4145:   vrndscalepd(dst, xtmp1, 0x4, vec_enc);
> 4146:   evcvtpd2qq(dst, dst, vec_enc);

Why do we need vrndscalepd in between, could we not directly use cvtpd2qq after vaddpd?

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