RFR: 8351661: NMT: VMATree should support separate call-stacks for reserve and commit operations [v10]

[Afshin Zafari]

On Wed, 9 Apr 2025 16:27:45 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fixed format of the missed Pre
>
> src/hotspot/share/nmt/vmatree.cpp line 69:
> 
>> 67:     stA.out.set_reserve_stack(NativeCallStackStorage::invalid);
>> 68:     stB.in.set_reserve_stack(NativeCallStackStorage::invalid);
>> 69:   }
> 
> I'd prefer to see this as:
> 
> 
>   // set default values, then depending on operation later, fill the required states
>   stA.out.set_commit_stack(NativeCallStackStorage::invalid);
>   stA.in.set_commit_stack(NativeCallStackStorage::invalid);
>   stA.out.set_reserve_stack(NativeCallStackStorage::invalid);
>   stB.in.set_reserve_stack(NativeCallStackStorage::invalid);
> 
>    if (is_reserve_operation) {
>     stA.out.set_reserve_stack(metadata.stack_idx);
>     stB.in.set_reserve_stack(metadata.stack_idx);
>   }
> 
>   if (is_commit_operation) {
>     stA.out.set_commit_stack(metadata.stack_idx);
>     stB.in.set_commit_stack(metadata.stack_idx);
>   }
> 
> 
> 
> Than later on we can skip setting these default values altogether and only touch the ones we need to.

Done.

> src/hotspot/share/nmt/vmatree.cpp line 147:
> 
>> 145:         stB.in.set_reserve_stack(leqA_n->val().out.reserved_stack());
>> 146:         stA.out.set_commit_stack(NativeCallStackStorage::invalid);
>> 147:         stB.in.set_commit_stack(NativeCallStackStorage::invalid);
> 
> Wouldn't need to do those if we followed my suggestion above?

Done.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/24028#discussion_r2036980496
PR Review Comment: https://git.openjdk.org/jdk/pull/24028#discussion_r2036981033