RFR: 8285487: AArch64: Do not generate unneeded trampolines for runtime calls [v6]

[Evgeny Astigeevich]

On Tue, 16 Aug 2022 10:05:37 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Evgeny Astigeevich has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Clarify non-compiled method in comments
>
> src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 871:
> 
>> 869:               : CodeCache::low_bound();
>> 870:       return Assembler::reachable_from_branch_at(longest_branch_start, target);
>> 871:     }
> 
> When does it happen that code outside the code cache (presumably in native shared libraries) is reachable? How did you test it?

This is the fix of:
[JDK-8286314](https://bugs.openjdk.org/browse/JDK-8286314): Trampoline not created for far runtime targets outside small CodeCache

At the time of writing the fix I could not find how to test the fix. We don't generate such trampoline calls.

I think if such calls appear, they will always be unreachable.

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PR: https://git.openjdk.org/jdk/pull/8403