RFR: 8343559: Optimize Class.getMethod(String, Class<?>...) for methods with no-arg [v2]

[jengebr]

> This change optimizes the runtime of `Class.getMethod(String, Class<?>[])` in two ways:
> 
> 1. While iterating across each Method to find a match (existing logic) it now compares parameter count before checking method name.  This check is substantially faster.
> 2. While iterating (existing logic) if the requested method has no arguments, the loop terminates early after finding one match.  This works because there can only be one zero-arg method with the matching name in the specific class.
> 
> A benchmark and unit tests are included; benchmark results (below) show an improvement in all cases, and an especially large gain when the immediate class contains the no-arg target.
> 
> Base:
> 
> Benchmark                          Mode  Cnt     Score    Error  Units
> ClassGetMethod.getConcreteFiveArg  avgt    6    90.866 ±  2.698  ns/op
> ClassGetMethod.getConcreteNoArg    avgt    6    72.472 ± 10.225  ns/op
> ClassGetMethod.getIntfFiveArg      avgt    6   198.524 ±  7.089  ns/op
> ClassGetMethod.getIntfNoArg        avgt    6   191.739 ±  4.695  ns/op
> ClassGetMethod.getNoSuchMethod     avgt   10  2254.308 ± 42.829  ns/op
> ClassGetMethod.getSuperFiveArg     avgt    6   165.897 ±  4.370  ns/op
> ClassGetMethod.getSuperNoArg       avgt    6   148.361 ±  4.573  ns/op
> 
> 
> Modified:
> 
> Benchmark                          Mode  Cnt     Score    Error  Units
> ClassGetMethod.getConcreteFiveArg  avgt    6    77.059 ±  2.644  ns/op
> ClassGetMethod.getConcreteNoArg    avgt    6    47.666 ±  6.544  ns/op
> ClassGetMethod.getIntfFiveArg      avgt    6   164.427 ±  4.356  ns/op
> ClassGetMethod.getIntfNoArg        avgt    6   161.256 ±  6.832  ns/op
> ClassGetMethod.getNoSuchMethod     avgt   10  2158.844 ± 43.716  ns/op
> ClassGetMethod.getSuperFiveArg     avgt    6   129.047 ±  4.414  ns/op
> ClassGetMethod.getSuperNoArg       avgt    6   123.728 ±  6.182  ns/op

jengebr has updated the pull request incrementally with three additional commits since the last revision:

 - Optimizing filter logic by internalizing loop
 - Enhancing benchmark + tests with additional 5-arg cases
 - Removing no-arg optimization

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21929/files
  - new: https://git.openjdk.org/jdk/pull/21929/files/4a007cc2..b0b63ecb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21929&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21929&range=00-01

  Stats: 35 lines in 3 files changed: 27 ins; 4 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/21929.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21929/head:pull/21929

PR: https://git.openjdk.org/jdk/pull/21929