RFR: 8254693: Add Panama feature to pass heap segments to native code [v12]

[Jorn Vernee]

On Wed, 8 Nov 2023 19:52:00 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - a -> an
>>  - add note to downcallHandle about passing heap segments by-reference
>
> src/hotspot/cpu/aarch64/downcallLinker_aarch64.cpp line 182:
> 
>> 180:   ArgumentShuffle arg_shuffle(filtered_java_regs, out_regs, shuffle_reg);
>> 181: 
>> 182: #ifndef PRODUCT
> 
> Any particular reason to exclude the logging in product builds? `ArgumentShuffle::print_on()` is unconditionally available there.

This is partly historical. The log output is only intended for debugging, not for end-user eyes. So, I think I originally excluded it as a way of trimming fat from the product build.

Either way, `ArgumentShuffle::print_on` should probably be excluded/included on the same basis.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16201#discussion_r1388189136