RFR: 8303852: current_stack_region() gets called twice unnecessarily [v3]

[Thomas Stuefe]

On Mon, 21 Aug 2023 03:46:10 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> We combine:
>> 
>> address os::current_stack_base();
>> size_t os::current_stack_size();
>> 
>> into
>> 
>> void os::current_stack_base_and_size(address* stack_base, size_t* stack_size)
>> 
>> and so avoid making two underlying system calls. The os/platform specific specializations are handled by the `current_stack_region` calls. It made sense to modify that to export the `base` directly rather than the `bottom`. In doing that change it made sense to standardise on the the style of the code used (variable names etc) to make it easier to see where the 5 different versions were the same and where they differ. Having 5 versions is unfortunate ( 3 BSD: one per arch - zero, x64, aarch64; and 2 linux: zero and everything else), but trying to combine them with ifdefs would be even worse in my opinion.
>> 
>> In theory there should be zero functional changes here.
>> 
>> Testing:
>>  - Tiers 1-3
>>  - All our internal builds in tiers 1-5
>>  - GHA
>> 
>> Thanks.
>
> David Holmes has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Promote os::<os>::current_stack_region to os::current_stack_base_and_size

Still good. Thanks for fixing this.

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PR Comment: https://git.openjdk.org/jdk/pull/15321#issuecomment-1685972097