RFR: 8255894: Remove unused StubRoutines::_zero_aligned_words

[Aleksey Shipilev]

On Wed, 4 Nov 2020 12:28:25 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>>> FWIW, we are still building Zero on SPARC in Debian. So, if there is an extra alignment that's needed on SPARC, I'd appreciate if it could stay in in case it's required for SPARC.
>> 
>> This is not about Zero VM. This stub is supposed to be _zeroing the memory_, and it is not used at all, AFAICS. So there is no breakage for Zero VM on SPARC.
>
>> FWIW, we are still building Zero on SPARC in Debian. So, if there is an extra alignment that's needed on SPARC, I'd appreciate if it could stay in in case it's required for SPARC.
> 
> This routine was used as part of an optimization of  [pd_fill_to_aligned_words](https://github.com/openjdk/jdk/commit/644620568827ddd5f5a4dc130d615ed6fd915c2d#diff-fe8c06a22855cd5f58f908f73109212d77cca26ec0c422d90496ebeedefe770d) on SPARC. I'm not sure how this method looks in your source tree now since all the flags that control this has been dropped from the mainline.

After looking at `copy_zero.hpp`, I believe Zero uses its own `pd_fill_to_aligned_words` and `pd_fill_to_words`. AFAIU, Zero tries to avoid the arch-specific code as much as possible, and that also extends to not using the "usual" stubs that require arch-specific generators.

-------------

PR: https://git.openjdk.java.net/jdk/pull/1053