RFR: 8326378: [PPC64] CodeEntryAlignment too large

[Lutz Schmidt]

On Thu, 22 Feb 2024 04:49:03 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> src/hotspot/cpu/ppc/globals_ppc.hpp line 62:
>> 
>>> 60: 
>>> 61: // Use large code-entry alignment.
>>> 62: define_pd_global(uintx, CodeCacheSegmentSize,  128);
>> 
>> Shouldn't also changing CodeCacheSegmentSize to match CodeEntryAlignment save a little more in the code cache?
>> 
>> If we did all alignment on the actual address rather than an offset that is relative, I think we could get rid of some of the constraints that require CodeCacheSegmentSize to be at least as large as CodeEntryAlignment and OptoLoopAlignment.
>
> This may make sense. However, almost all platforms use a CodeCacheSegmentSize of 128 Bytes. So, I think this should better get addressed separately for all platforms.

Interesting suggestion. I created JDK-8326571 as follow-up to work on the topic.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17939#discussion_r1500503855