RFR: 8332602: [s390x] Improve itable_stub [v2]

[Amit Kumar]

On Fri, 14 Jun 2024 02:49:44 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;
>
> Amit Kumar has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Update src/hotspot/cpu/s390/macroAssembler_s390.hpp
>  - Update src/hotspot/cpu/s390/macroAssembler_s390.hpp

src/hotspot/cpu/s390/macroAssembler_s390.cpp line 2855:

> 2853:   //     }
> 2854:   //     scan_temp += itable_offset_entry_size
> 2855:   //   } while (temp_itbl_klass != 0);

Suggestion:

  //   do {
  //     scan_temp += itable_offset_entry_size
  //     temp_itbl_klass = *(scan_temp);
  //     if (temp_itbl_klass == holder_klass) {
  //       goto holder_found; // Found!
  //     }
  //   } while (temp_itbl_klass != 0);

src/hotspot/cpu/s390/macroAssembler_s390.cpp line 2871:

> 2869:   //   while (true) {
> 2870:   //     temp_itbl_klass = *(scan_temp);
> 2871:   //     scan_temp += itable_offset_entry_size

Suggestion:

  //   while (true) {
  //     scan_temp += itable_offset_entry_size
  //     temp_itbl_klass = *(scan_temp);

src/hotspot/cpu/s390/macroAssembler_s390.hpp line 678:

> 676:                                     Register r_method_result,
> 677:                                     Register r_temp,
> 678:                                     Register r_temp2,

Suggestion:

  void lookup_interface_method_stub(Register recv_klass,
                                    Register holder_klass,
                                    Register resolved_klass,
                                    Register method_result,
                                    Register temp,
                                    Register temp2,

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

PR Review Comment: https://git.openjdk.org/jdk/pull/19698#discussion_r1639152975
PR Review Comment: https://git.openjdk.org/jdk/pull/19698#discussion_r1639154532
PR Review Comment: https://git.openjdk.org/jdk/pull/19698#discussion_r1639156209