RFR: 8343559: Optimize Class.getMethod(String, Class<?>...) for methods with no-arg [v3]

[jengebr]

> This change optimizes the runtime of `Class.getMethod(String, Class<?>[])` by reducing the cost of the existing search logic.  Specifically, 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.
> 
> 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    94.586 ±  0.733  ns/op
> ClassGetMethod.getConcreteNoArg    avgt    6    75.587 ± 11.300  ns/op
> ClassGetMethod.getIntfFiveArg      avgt    6   215.794 ±  7.713  ns/op
> ClassGetMethod.getIntfNoArg        avgt    6   200.418 ±  4.352  ns/op
> ClassGetMethod.getNoSuchMethod     avgt   10  2207.928 ± 49.767  ns/op
> ClassGetMethod.getSuperFiveArg     avgt    6   190.142 ±  1.995  ns/op
> ClassGetMethod.getSuperNoArg       avgt    6   153.943 ±  7.491  ns/op
> 
> 
> Modified:
> 
> Benchmark                          Mode  Cnt     Score    Error  Units
> ClassGetMethod.getConcreteFiveArg  avgt    6    94.409 ±  1.642  ns/op
> ClassGetMethod.getConcreteNoArg    avgt    6    77.748 ± 11.618  ns/op
> ClassGetMethod.getIntfFiveArg      avgt    6   193.816 ±  4.250  ns/op
> ClassGetMethod.getIntfNoArg        avgt    6   205.565 ±  9.140  ns/op
> ClassGetMethod.getNoSuchMethod     avgt   10  2231.248 ± 67.711  ns/op
> ClassGetMethod.getSuperFiveArg     avgt    6   169.971 ±  0.883  ns/op
> ClassGetMethod.getSuperNoArg       avgt    6   129.188 ±  8.421  ns/op

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

  Switching back to Array.equals() for parameter type comparison loop

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21929/files
  - new: https://git.openjdk.org/jdk/pull/21929/files/b0b63ecb..55f7e372

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21929&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21929&range=01-02

  Stats: 11 lines in 1 file changed: 0 ins; 5 del; 6 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