std::sort() may cause cross-platform performance mismatch

[hanhuang]

The std::sort() may produce different results in different platforms (linux and windows for examples) if some of the elements have equal comparison values. Therefore, could cause different encoding results using the same VTM.
There are two std::sort function calls that are identified to have potential issue. One in IntraSearch::xSortISPCandList and the other in EncAdaptiveLoopFilter::determineControlIdcValues.

It's suggested to replace std::sort with std::stable_sort to avoid potential cross-platform performance mismatch.

[fbossen]

Yes, it would make sense to use stable_sort in these cases for consistency. Presumably the arrays are small enough such that no impact on runtime is expected.
What about GeoComboCostList::sortByCost ?

[hanhuang]

Replying to fbossen:

Yes, it would make sense to use stable_sort in these cases for consistency. Presumably the arrays are small enough such that no impact on runtime is expected.
What about GeoComboCostList::sortByCost ?

Yes, the sortByCost one also need to replace sort() by stable_sort().

[fbossen]

Replying to hanhuang:

Replying to fbossen:

Yes, it would make sense to use stable_sort in these cases for consistency. Presumably the arrays are small enough such that no impact on runtime is expected.
What about GeoComboCostList::sortByCost ?

Yes, the sortByCost one also need to replace sort() by stable_sort().

Can you submit a merge request?

[hanhuang]

Sure. A merge request !2022 was just submitted.
Replying to fbossen:

Can you submit a merge request?

[fbossen]

Fixed in ​https://vcgit.hhi.fraunhofer.de/jvet/VVCSoftware_VTM/-/merge_requests/2022