RFR: 8367325: [s390x] build failure due to JDK-8361376 [v2]

[Amit Kumar]

On Mon, 15 Sep 2025 10:49:20 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> Amit Kumar has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   better fix
>
> src/hotspot/cpu/s390/gc/shared/barrierSetAssembler_s390.hpp line 70:
> 
>> 68: #endif // COMPILER2
>> 69: 
>> 70:   static const int PATCHABLE_INSTRUCTION_OFFSET = 3 * 6 + 2;
> 
> Maybe better call it `PATCHABLE_BARRIER_VALUE_OFFSET`?
> It's no longer the instruction start address.
> Or even better: define 2 constants. The version without the +2 is still needed below.

I have given name as `PATCHABLE_SEQ_START_OFFSET` and `PATCHABLE_BARRIER_VALUE_OFFSET`. Please let me  know if there is better option :)

> src/hotspot/cpu/s390/gc/shared/barrierSetNMethod_s390.cpp line 43:
> 
>> 41:       address inst_addr = get_barrier_start_address() + BarrierSetAssembler::PATCHABLE_INSTRUCTION_OFFSET;
>> 42: 
>> 43:       DEBUG_ONLY(Assembler::is_z_cfi(*((long*)inst_addr)));
> 
> The cfi check needs an adjustment to point to the instruction start, right?

Now It is pointing to `z_cfi`: 


(gdb) x/i inst_addr 
   0x3ffe500017a:	cfi	%r0,0

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PR Review Comment: https://git.openjdk.org/jdk/pull/27213#discussion_r2354402837
PR Review Comment: https://git.openjdk.org/jdk/pull/27213#discussion_r2354399640