RFR: 8331126: [s390x] secondary_super_cache does not scale well [v6]

[Amit Kumar]

On Thu, 27 Jun 2024 02:52:18 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

>> src/hotspot/cpu/s390/macroAssembler_s390.cpp line 3452:
>> 
>>> 3450:   z_lgr(Z_ARG4, r_result);
>>> 3451:   const char* msg = "mismatch";
>>> 3452:   load_const_optimized(Z_ARG5, (address)msg);
>> 
>> Did you test this? It breaks when you have a register collision (see my assert_different_registers on PPC64). You can test it by removing the `z_bre` above and checking if the arguments are correct.
>
> I found one log, from when I was implementing this: 
> 
> fatal error: mismatch: java.lang.Integer implements java.util.concurrent.Callable: is_subtype_of: 0; linear_search: 0; table_lookup: 1
> 
> Context: repne_scan wasn't working properly, table_lookup came up to "1" and repne_scan returned "0" so check failed.
> 
>  For surety let me just add the asserts as well and see what happens.

>You can test it by removing the z_bre above and checking if the arguments are correct.

I have tested with your suggestion, in tier1 there were more then 500 failures, all of them were failing with mismatch error only. I didn't see any register clobbering.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19544#discussion_r1658397411