RFR: 8342540: InterfaceCalls micro-benchmark gives misleading results [v2]

[Andrew Haley]

> `InterfaceCalls.java` makes highly predictable memory accesses, which leads to a gross time underestimate of the case where a megamorphic access is unpredictable.
> 
> Here's one example, with and without randomization. The unpredictable megamorphic call takes more than 4* as long as the benchmark.
> 
> 
> Benchmark                            (randomized)  Mode  Cnt   Score   Error  Units
> InterfaceCalls.test2ndInt3Types             false  avgt    4   5.013 ± 0.081  ns/op
> InterfaceCalls.test2ndInt3Types              true  avgt    4  23.421 ± 0.102  ns/op
> ``` 
> 
> This patch adds the "randomized" parameter, which allows the measurement of predictable and unpredictable megamorphic calls.

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

  Update test/micro/org/openjdk/bench/vm/compiler/InterfaceCalls.java
  
  Co-authored-by: Aleksey Shipilëv <shipilev at amazon.de>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21581/files
  - new: https://git.openjdk.org/jdk/pull/21581/files/c3fa63c5..52f80b28

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21581&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21581&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/21581.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21581/head:pull/21581

PR: https://git.openjdk.org/jdk/pull/21581