RFR: 8318159: RISC-V: Improve itable_stub [v2]

[Fei Yang]

On Mon, 20 Nov 2023 16:20:52 GMT, Yuri Gaevsky <duke at openjdk.org> wrote:

>> Please review the change for RISC-V similar to #13792(AARCH64) and #13460(X86).
>> 
>> From #13792:
>> The change replaces two separate iterations over the itable with new algorithm
>> consisting of two loops. First, we look for a match with resolved_klass,
>> checking for a match with holder_klass along the way. Then we continue iterating
>> (not starting over) the itable using the second loop, checking only for a match
>> with holder_klass.
>> 
>> ### Correctness checks
>> 
>> Testing: tier1 tests successfully passed on HiFive Unmatched board.
>> 
>> #### Performance results on RISC-V StarFive JH7110 board:
>> 
>> 
>> InterfaceCalls:                  before fix        after fix
>> -------------------------------------------------------------------
>> Benchmark         Mode  Cnt   Score   Error    Score   Error  Units
>> -------------------------------------------------------------------
>> test1stInt2Types  avgt  100  14.380 ? 0.017 | 14.370 ? 0.014  ns/op
>> test1stInt3Types  avgt  100  72.724 ? 0.552 | 66.290 ? 0.080  ns/op
>> test1stInt5Types  avgt  100  73.948 ? 0.524 | 68.781 ? 0.377  ns/op
>> test2ndInt2Types  avgt  100  15.705 ? 0.016 | 15.707 ? 0.018  ns/op
>> test2ndInt3Types  avgt  100  82.370 ? 0.453 | 75.363 ? 0.156  ns/op
>> test2ndInt5Types  avgt  100  85.266 ? 0.466 | 80.969 ? 0.752  ns/op
>> testIfaceCall     avgt  100  75.684 ? 0.648 | 72.603 ? 0.460  ns/op
>> testIfaceExtCall  avgt  100  86.293 ? 0.567 | 77.939 ? 0.340  ns/op
>> testMonomorphic   avgt  100  11.357 ? 0.007 | 11.359 ? 0.009  ns/op
>> -------------------------------------------------------------------
>> 
>> 
>> #### Performance results on RISC-V HiFive Unmatched board:
>> 
>> 
>> InterfaceCalls:                   before fix         after fix
>> ---------------------------------------------------------------------
>> Benchmark         Mode  Cnt    Score   Error     Score   Error  Units
>> ---------------------------------------------------------------------
>> test1stInt2Types  avgt  100   24.432 ? 1.811 |  23.205 ? 1.512  ns/op
>> test1stInt3Types  avgt  100  135.800 ? 3.991 | 127.112 ? 2.299  ns/op
>> test1stInt5Types  avgt  100  141.746 ? 4.272 | 136.069 ? 4.919  ns/op
>> test2ndInt2Types  avgt  100   31.474 ? 2.468 |  26.978 ? 1.951  ns/op
>> test2ndInt3Types  avgt  100  146.410 ? 3.575 | 139.443 ? 3.677  ns/op
>> test2ndInt5Types  avgt  100  156.083 ? 3.617 | 150.583 ? 2.909  ns/op
>> testIfaceCall     avgt  100  136.392 ? 2.546 | 129.632 ? 1.662  ns/op
>> testIfaceExtCall  avgt  100  155.602 ? 3.836 | 138.058 ...
>
> Yuri Gaevsky has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Addressed review comments from @RealFYang and @robehn.

Updated change looks good. Thanks.

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

Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/16657#pullrequestreview-1740910077