* When multiple buffers are aliased over the same heap memory, they'll have the
same GPU base address. Our mapping needs to ensure it removes the right entry
when a resource is released.
* On GL/D3D11 we delay the start of the 'first frame' until a swapchain has been
created for D3D11, or an attribs-created context has been created for GL. This
makes it more useful and doesn't fire when creating devices/contexts for
enumeration or trampolining.
* On Vulkan/D3D12 the first device that's created is useful, so we can start
capturing immediately once it's available.
* When a descriptor table is unbounded in the root signature we don't want to
pass potentially multiple 100k descriptors through just because they're
technically available.
* Instead use the declared array size of the last register in the space (since a
descriptor table in the RS might correspond to multiple HLSL variables) to
limit which registers are actually available, which is possibly orders of
magnitude less.
* Even if a struct isn't trivial (e.g. it contains a constructor) it can still
be trivially copyable (just POD with memcpy), or trivially destructable (with
no destructor). Make sure we don't fall back to slower copies/destroys for
this case as it's relatively common.
* When we have a cached buffer that already has the map contents, reserialising
the byte buffer is pointless as we don't use it for anything.
* The serialise involves allocating a buffer, memcpy'ing it, then freeing it
which can add up for large map writes.
* We now take a more vulkan-like approach, by forcing READ_BIT on for
buffers/maps that are coherent, and leaving it alone while idle. During
capture we do the same memcmp & save updates as before.
* This is signifcantly faster while idle, though still slow to capture due to
the number of sync points in GL (per draw). Roughly scales with O(m*n) where m
= number of bytes of memory coherently mapped and n = number of draws in a
frame.
baldurk