RFR: 8309717: C2: Remove Arena::move_contents usage [v2]

[Tobias Hartmann]

On Wed, 14 Jun 2023 12:34:51 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Hi,
>> 
>> Instead of using `Arena::move_contents` we can just see the arena swap as a form of double buffering, reducing this to a pointer swap and a clear. This allows us to remove `Arena::move_contents`, cleaning up the arena code.
>> 
>> Since this requires allocating another pointer for `Compile`, I took the time to move some members around in order to reduce the padding. This means that this patch does *not* introduce a size change for `Compile`.
>> 
>> I'm currently running tier1-3 tests.
>> 
>> Thanks for considering this,
>> Johan
>
> Johan Sjölen has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Update src/hotspot/share/opto/matcher.cpp
>    
>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>  - Update src/hotspot/share/opto/compile.hpp
>    
>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>

Marked as reviewed by thartmann (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/14391#pullrequestreview-1480680863