So far we were saving all the descriptor info on the host memory. With
this commit we do the equivalent that other mesa vulkan drivers (Anvil
and Turnip) and create a bo on the descriptor pool that would be
suballocated for each descriptor.
This would allow to clean up individual bos from some vulkan objects,
reducing device memory fragmentation, and allowing to avoid to alloc
bos for that info. After all, pre-allocating needed memory is one of
the purposes of the descriptor pool.
This commit introduces all the infrastructure, but doesn't use it for
any descriptor yet, as if no descriptor needed data uploaded to a bo.
The idea to decide which info goes to the descriptor pool bo is info
that we would need to upload to a bo in any case, as it is referenced
as an address by any packet.
We could be more aggressive with that general rule, but that would be
enough for now. If in the future we support
VK_EXT_descriptor_indexing, we probably would need to store more info,
as under that extension, descriptors can be updated after being bound.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>
Alejandro Piñeiro
18553b50f9