Following 3a839517ce, SparseGrid::Reset() replaces the value of m_Data
(a C-style dynamically sized array) with a new value-initialised array,
by using the new operator. Previous code simply did a memset.
This means that when m_Data was not null, it leaked memory as the
previous array was not deleted.
SparseGrid::Reset is called when destroying the sparse grid, and a
SparseGrid is used by the long pathfinder when computing JPS paths. As
that is called rather often, it resulted in a relatively serious memory
leak that could make very long games use several GB of memory.
This fixes the leak by using placement new, which re-uses the memory,
effectively doing the same as the previously existing memset.
Profiling by historic_bruno and elexis showed that performance from
value-initialising with placement new was at worst similar to memset,
and testing shows this was compiled in a memset call in several cases
anyways.
Reviewed By: elexis
Fixes#5522
Differential Revision: https://code.wildfiregames.com/D2121
This was SVN commit r22545.
2cc071f306