RFR: 8339983: [s390x] secondary_super_cache does not scale well: C1 and interpreter [v2]

[Amit Kumar]

On Mon, 25 Nov 2024 15:42:01 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Amit Kumar has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   suggestion from Andrew
>
> src/hotspot/cpu/s390/macroAssembler_s390.cpp line 3432:
> 
>> 3430:     r_array_index = temp3,
>> 3431:     slot          = temp4, // NOTE: "slot" can't be Z_R0 otherwise z_sllg and z_rllg instructions below will mess up!!!!
>> 3432:     r_bitmap      = Z_R1_scratch;
> 
> Why is `r_bitmap` a fixed register?
> Do you push `Z_R1` somewhere?

No Z_R1 is scratch register and is free. It is not being used by `lookup_secondary_supers_table_slow_path` or `repne_scan`.  So can't we use it here ?

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PR Review Comment: https://git.openjdk.org/jdk/pull/22341#discussion_r1856859628