RFR: 8279508: Auto-vectorize Math.round API [v2]

[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)
> 
>   |   | BASELINE AVX2 | WithOpt AVX2 | Gain (opt/baseline) | Baseline AVX3 | Withopt AVX3 | Gain (opt/baseline)
> -- | -- | -- | -- | -- | -- | -- | --
> Benchmark | ARRAYLEN | Score (ops/ms) | Score (ops/ms) |   | Score (ops/ms) | Score (ops/ms) |  
> FpRoundingBenchmark.test_round_double | 1024 | 518.532 | 1364.066 | 2.630630318 | 512.908 | 4292.11 | 8.368186887
> FpRoundingBenchmark.test_round_double | 2048 | 270.137 | 830.986 | 3.076165057 | 273.159 | 2459.116 | 9.002507697
> FpRoundingBenchmark.test_round_float | 1024 | 752.436 | 7780.905 | 10.34095259 | 752.49 | 9506.694 | 12.63364829
> FpRoundingBenchmark.test_round_float | 2048 | 389.499 | 4113.046 | 10.55983712 | 389.63 | 4863.673 | 12.48279907
> 
> 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: Adding a test for scalar intrinsification.

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7094/files
  - new: https://git.openjdk.java.net/jdk/pull/7094/files/0fe01504..575d2935

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7094&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7094&range=00-01

  Stats: 2 lines in 2 files changed: 2 ins; 0 del; 0 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