RFR: 8349686: [s390x] C1: Improve Class.isInstance intrinsic [v8]

[Andrew Haley]

On Thu, 20 Feb 2025 10:48:45 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

>> src/hotspot/cpu/s390/macroAssembler_s390.cpp line 3674:
>> 
>>> 3672:                                                    Register r_temp2,
>>> 3673:                                                    Register r_temp3) {
>>> 3674:   assert_different_registers(r_sub_klass, r_super_klass, r_result, r_temp1, r_temp2, r_temp3, Z_R0_scratch);
>> 
>> Suggestion:
>> 
>>   assert_different_registers(r_sub_klass, r_super_klass, r_result, r_temp1, r_temp2, r_temp3);
>
> But we are still using Z_R0, to resize the frame, at line 3708 and 3718.

I missed that because you were using different names for the same register in this function. I searched for `Z_R0_scratch`. It would be better if you decided what to call `Z_R0`, and used the same name consistently for all usages, including `assert_different_registers()`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23535#discussion_r1963400828