[master] RFR: JDK-8307737: [Lilliput] Reduce number of loads used for Klass decoding in static code [v2]

[Thomas Stuefe]

On Wed, 10 May 2023 10:30:47 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix SA tests
>
> src/hotspot/share/oops/compressedKlass.cpp line 101:
> 
>> 99:   assert((((uintptr_t)thebase) & ~baseAddressMask) == 0, "Base address " PTR_FORMAT " unaligned", p2i(thebase));
>> 100: 
>> 101:   _value = (UseCompactObjectHeaders ? ((uintptr_t)1 << useCompactObjectHeadersShift) : 0) |
> 
> I am not sure that _value is a good name. Maybe _config or so?

Okay, _config it is.

> src/hotspot/share/oops/compressedKlass.hpp line 89:
> 
>> 87:   static void set_use_compressed_class_pointers(bool b);
>> 88: 
>> 89:   // These members hold copies of encoding base and shift and only exist for SA (see vmStructs.cpp and
> 
> I guess, SA could be changed to decode the config bits? Maybe not in this PR, though.

Yes, we should fix that.

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PR Review Comment: https://git.openjdk.org/lilliput/pull/92#discussion_r1189766737
PR Review Comment: https://git.openjdk.org/lilliput/pull/92#discussion_r1189766556