RFR: 8293254: x86_64: Extract arraycopy stub implementations into a separate file

[Dean Long]

On Thu, 1 Sep 2022 20:30:37 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> Move arraycopy stub implementations from `stubGenerator_x86_64.cpp` into `stubGenerator_x86_64_arraycopy.cpp`.
> 
> Testing: hs-tier1 - hs-tier4
> 
> PS: FTR I left `MacroAssembler::generate_fill_avx3()` intact because it is called from `MacroAssembler::generate_fill()` which is shared between x86_64 and x86_32. Otherwise, I would either need to copy `MacroAssembler::generate_fill()` or put it into a separate file (e.g., `stubGenerator_x86.cpp` or `stubGenerator_x86_arraycopy.cpp`). IMO it doesn't add much value compared to keeping it in `macroAssembler_x86.cpp`.

It seems OK, assuming there are no hidden changes, just cut and paste plus renames and adding "__ ".  Considering the number of lines changes, it would be hard for a reviewer to check all the lines without effectively reproducing all the steps.

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Marked as reviewed by dlong (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10128