RFR: 8279508: Auto-vectorize Math.round API [v16]

[Jatin Bhateja]

> 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)
> 
> 
> Benchmark | TESTSIZE | Baseline AVX3 (ops/ms) | Withopt AVX3 (ops/ms) | Gain ratio | Baseline AVX2 (ops/ms) | Withopt AVX2 (ops/ms) | Gain ratio
> -- | -- | -- | -- | -- | -- | -- | --
> FpRoundingBenchmark.test_round_double | 1024.00 | 504.15 | 2209.54 | 4.38 | 510.36 | 548.39 | 1.07
> FpRoundingBenchmark.test_round_double | 2048.00 | 293.64 | 1271.98 | 4.33 | 293.48 | 274.01 | 0.93
> FpRoundingBenchmark.test_round_float | 1024.00 | 825.99 | 4754.66 | 5.76 | 751.83 | 2274.13 | 3.02
> FpRoundingBenchmark.test_round_float | 2048.00 | 412.22 | 2490.09 | 6.04 | 388.52 | 1334.18 | 3.43
> 
> 
> 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: Styling comments resolved.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7094/files
  - new: https://git.openjdk.java.net/jdk/pull/7094/files/e4d4e29b..c881d11c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7094&range=15
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7094&range=14-15

  Stats: 11 lines in 3 files changed: 3 ins; 3 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7094.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7094/head:pull/7094

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