RFR: 8350459: MontgomeryIntegerPolynomialP256 multiply intrinsic with AVX2 on x86_64 [v4]

[Volodymyr Paprotski]

> Add AVX2 montgomery multiplication intrinsic. (About 60-80% gain)
> 
> Also add reduction to existing AVX512 multiplication (this was left-over from https://github.com/openjdk/jdk/pull/19893 where a quick fix was required). This is mostly for cleanup, but there is about 1-2% gain.
> 
> Before (no AVX512)
> 
> Benchmark                        (algorithm)  (dataSize)  (keyLength)  (provider)   Mode  Cnt      Score     Error  Units
> SignatureBench.ECDSA.sign    SHA256withECDSA        1024          256              thrpt   40   3720.589 ±  17.879  ops/s
> SignatureBench.ECDSA.sign    SHA256withECDSA       16384          256              thrpt   40   3605.940 ±  15.807  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA        1024          256              thrpt   40   1076.502 ±   4.190  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA       16384          256              thrpt   40   1069.624 ±   2.484  ops/s
> Benchmark                             (algorithm)  (keyLength)  (kpgAlgorithm)  (provider)   Mode  Cnt     Score   Error  Units
> KeyAgreementBench.EC.generateSecret          ECDH          256              EC              thrpt   40   830.448 ± 2.285  ops/s
> 
> After (with AVX2)
> 
> Benchmark                        (algorithm)  (dataSize)  (keyLength)  (provider)   Mode  Cnt      Score     Error  Units
> SignatureBench.ECDSA.sign    SHA256withECDSA        1024          256              thrpt   40   6000.496 ±  39.923  ops/s
> SignatureBench.ECDSA.sign    SHA256withECDSA       16384          256              thrpt   40   5739.878 ±  34.838  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA        1024          256              thrpt   40   1942.437 ±  12.179  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA       16384          256              thrpt   40   1921.770 ±   8.992  ops/s
> Benchmark                             (algorithm)  (keyLength)  (kpgAlgorithm)  (provider)   Mode  Cnt     Score   Error  Units
> KeyAgreementBench.EC.generateSecret          ECDH          256              EC              thrpt   40  1399.761 ± 6.238  ops/s
> 
> 
> Before (with AVX512):
> 
> Benchmark                        (algorithm)  (dataSize)  (keyLength)  (provider)   Mode  Cnt       Score     Error  Units
> SignatureBench.ECDSA.sign    SHA256withECDSA        1024          256              thrpt   40    9621.950 ±  27.260  ops/s
> SignatureBench.ECDSA.sign    SHA256withECDSA       16384          256              thrpt   40    8975.654 ±  26.707  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA        102...

Volodymyr Paprotski has updated the pull request incrementally with one additional commit since the last revision:

  more comment improvements

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23719/files
  - new: https://git.openjdk.org/jdk/pull/23719/files/bb450137..9d13cefa

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23719&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23719&range=02-03

  Stats: 72 lines in 2 files changed: 45 ins; 5 del; 22 mod
  Patch: https://git.openjdk.org/jdk/pull/23719.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23719/head:pull/23719

PR: https://git.openjdk.org/jdk/pull/23719