RFR: 8329538: Accelerate P256 on x86_64 using Montgomery intrinsic [v6]

[Volodymyr Paprotski]

> Performance. Before:
> 
> Benchmark                        (algorithm)  (dataSize)  (keyLength)  (provider)   Mode  Cnt     Score    Error  Units
> SignatureBench.ECDSA.sign    SHA256withECDSA        1024          256              thrpt    3  6443.934 ±  6.491  ops/s
> SignatureBench.ECDSA.sign    SHA256withECDSA       16384          256              thrpt    3  6152.979 ±  4.954  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA        1024          256              thrpt    3  1895.410 ± 36.979  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA       16384          256              thrpt    3  1878.955 ± 45.487  ops/s
> Benchmark                                            (algorithm)  (keyLength)  (kpgAlgorithm)  (provider)   Mode  Cnt     Score    Error  Units
> o.o.b.j.c.full.KeyAgreementBench.EC.generateSecret          ECDH          256              EC              thrpt    3  1357.810 ± 26.584  ops/s
> o.o.b.j.c.small.KeyAgreementBench.EC.generateSecret         ECDH          256              EC              thrpt    3  1352.119 ± 23.547  ops/s
> Benchmark                          (isMontBench)   Mode  Cnt     Score    Error  Units
> PolynomialP256Bench.benchMultiply          false  thrpt    3  1746.126 ± 10.970  ops/s
> 
> Performance, no intrinsic:
> 
> Benchmark                        (algorithm)  (dataSize)  (keyLength)  (provider)   Mode  Cnt     Score     Error  Units
> SignatureBench.ECDSA.sign    SHA256withECDSA        1024          256              thrpt    3  6529.839 ±  42.420  ops/s
> SignatureBench.ECDSA.sign    SHA256withECDSA       16384          256              thrpt    3  6199.747 ± 133.566  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA        1024          256              thrpt    3  1973.676 ±  54.071  ops/s
> SignatureBench.ECDSA.verify  SHA256withECDSA       16384          256              thrpt    3  1932.127 ±  35.920  ops/s
> Benchmark                                            (algorithm)  (keyLength)  (kpgAlgorithm)  (provider)   Mode  Cnt     Score    Error  Units
> o.o.b.j.c.full.KeyAgreementBench.EC.generateSecret          ECDH          256              EC              thrpt    3  1355.788 ± 29.858  ops/s
> o.o.b.j.c.small.KeyAgreementBench.EC.generateSecret         ECDH          256              EC              thrpt    3  1346.523 ± 28.722  ops/s
> Benchmark                          (isMontBench)   Mode  Cnt     Score    Error  Units
> PolynomialP256Bench.benchMultiply           true  thrpt    3  1919.574 ± 10.591  ops/s
> 
> Performance, **with intrinsics*...

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

  Use AffinePoint to exit Montgomery domain
  
  Style notes:
  Affine.equals()
      - Mismatched fields only appear to be used from testing, perhaps should be moved there instead
  Affine.getX(boolean)|getY(boolean)
      - "Passing flag is bad design" - cleanest/performant alternative to several instanceof checks
      - needed to convert Affine to Projective (need to stay in montgomery domain)
  ECOperations.PointMultiplier
     - changes could probably be restored to original (since ProjectivePoint handling no longer required)
     - consider these changes an improvement? (fewer nested classes)
     - was an inner-class but not using inner-class features (i.e. ecOps variable should be converted)

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/18583/files
  - new: https://git.openjdk.org/jdk/pull/18583/files/a1984501..8ff243a2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=18583&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=18583&range=04-05

  Stats: 268 lines in 7 files changed: 89 ins; 147 del; 32 mod
  Patch: https://git.openjdk.org/jdk/pull/18583.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18583/head:pull/18583

PR: https://git.openjdk.org/jdk/pull/18583