RFR: 8333566: Remove unused methods

[Lutz Schmidt]

On Tue, 4 Jun 2024 20:51:52 GMT, Cesar Soares Lucas <cslucas at openjdk.org> wrote:

> Please, consider this patch to remove unused methods from the code base. To the best of my knowledge, these methods are only defined but never used.
> 
> Here is a list with names of delete methods: https://gist.github.com/JohnTortugo/fccc29781a1b584c03162aa4e160e874
> 
> Tested with Linux x86_64 tier1-4, GHA, and only cross building to other platforms.

I feel very uncomfortable with this PR, at least as far as s390 is concerned. Many of the methods now set to be removed have been implemented with "implementation completeness" in mind. Not being used currently does not allow the implication of being obsolete. The approach on s390 has always been to provide support for potentially useful new instructions once they become available. Later exploitation can then focus on the use, without bloating the PR with low-level assembler* declarations. 

There are a few exceptions, though. One is the code around `_atomic_memory_operation_lock`. That seems to be a leftover which simply was forgotten. Same seems true for `pd_relocate_CodeBlob`

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Changes requested by lucy (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19550#pullrequestreview-2104286082