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

[Andrew Haley]

On Tue, 16 Aug 2022 11:44:59 GMT, Evgeny Astigeevich <duke at openjdk.org> wrote:

>> 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.

Please take it out, then.

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