RFR: 8332602: [s390x] Improve itable_stub [v3]

[Amit Kumar]

On Fri, 14 Jun 2024 02:58:38 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

>> s390x Port similar to [JDK-8305959 (x86)](https://bugs.openjdk.org/browse/JDK-8305959) and [JDK-8307352(aarch64)](https://bugs.openjdk.org/browse/JDK-8307352)
>> 
>> Testing: I ran `tier1` test on fastdebug & release VM; I didn't see any regression there;
>> 
>> Benchmarking: 
>> 
>> Without Patch: 
>> Benchmark                        Mode  Cnt   Score    Error  Units
>> InterfaceCalls.test1stInt2Types  avgt   12   1.924 ±  0.001  ns/op
>> InterfaceCalls.test1stInt3Types  avgt   12  13.925 ±  0.014  ns/op
>> InterfaceCalls.test1stInt5Types  avgt   12  16.591 ±  0.045  ns/op
>> InterfaceCalls.test2ndInt2Types  avgt   12   2.028 ±  0.013  ns/op
>> InterfaceCalls.test2ndInt3Types  avgt   12   7.634 ±  0.049  ns/op
>> InterfaceCalls.test2ndInt5Types  avgt   12  16.231 ±  1.222  ns/op
>> InterfaceCalls.testIfaceCall     avgt   12  16.587 ±  0.058  ns/op
>> InterfaceCalls.testIfaceExtCall  avgt   12  17.532 ±  0.024  ns/op
>> InterfaceCalls.testMonomorphic   avgt   12   0.746 ±  0.001  ns/op
>> Finished running test 'micro:vm.compiler.InterfaceCalls'
>> 
>> 
>> With Patch: 
>> 
>> Benchmark                        Mode  Cnt   Score    Error  Units
>> InterfaceCalls.test1stInt2Types  avgt   12   1.929 ±  0.012  ns/op
>> InterfaceCalls.test1stInt3Types  avgt   12  13.280 ±  0.093  ns/op
>> InterfaceCalls.test1stInt5Types  avgt   12  16.169 ±  0.364  ns/op
>> InterfaceCalls.test2ndInt2Types  avgt   12   6.758 ±  4.473  ns/op
>> InterfaceCalls.test2ndInt3Types  avgt   12  11.772 ±  2.411  ns/op
>> InterfaceCalls.test2ndInt5Types  avgt   12  15.099 ±  0.081  ns/op
>> InterfaceCalls.testIfaceCall     avgt   12  15.972 ±  0.021  ns/op
>> InterfaceCalls.testIfaceExtCall  avgt   12  16.600 ±  0.322  ns/op
>> InterfaceCalls.testMonomorphic   avgt   12   0.746 ±  0.001  ns/op
>> Finished running test 'micro:vm.compiler.InterfaceCalls'
>
> Amit Kumar has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Update src/hotspot/cpu/s390/macroAssembler_s390.cpp
>  - Update src/hotspot/cpu/s390/macroAssembler_s390.cpp
>  - polishing

src/hotspot/cpu/s390/macroAssembler_s390.cpp line 2903:

> 2901:   z_bru(L_loop_search_resolved);
> 2902: 
> 2903:   bind(L_resolved_found);

Suggestion:

  // See if we already have a holder klass. If not, go and scan for it.
  bind(L_resolved_found);

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

PR Review Comment: https://git.openjdk.org/jdk/pull/19698#discussion_r1641002482