There's no limit on the number of memory exports in a shader on the real
Xenos, and exports can be done anywhere, including in loops. Now, instead
of deferring the exports to the end of the shader, and assuming that export
allocs are executed only once, Xenia flushes exports when it reaches an
alloc (allocs terminate memory exports on Xenos, as well as individual ALU
instructions with `serialize`, but not handling this case for simplicity,
it's only truly mandatory to flush memory exports before starting a new
one), the end of the shader, or a pixel with outstanding exports is killed.
To know which eM# registers need to be flushed to the memory, traversing
the successors of each exec potentially writing any eM#, and specifying
that certain eM# registers might have potentially been written before each
reached control flow instruction, until a flush point or the end of the
shader is reached.
Also, some games export to sub-32bpp formats. These are now supported via
atomic AND clearing the bits of the dword to replace followed by an atomic
OR inserting the new byte/short.
Also fixes addressing of MSAA samples 2 and 3 for 64bpp color render targets in the ROV RB implementation on Direct3D 12.
Additionally, with FSI/ROV, alpha test and alpha to coverage are done only if the render target 0 was dynamically written to (according to the Direct3D 9 rules for writing to color render targets, though not sure if they actually apply to the alpha tests on Direct3D 9, but for safety).
There is also some code cleanup for things spotted during the development of the feature.
For more optimal usage of exports and the parameter cache on the host regardless of how effective the optimizations in the host GPU driver are. Also reserve space for Vulkan/Metal/D3D11-specific HostVertexShaderTypes to use one more bit for the host vertex shader type in the shader modification bits, so that won't have to be done in the future as that would require invalidating shader storages (which are invalidated by this commit) again.
6fcf9d21fe made per-vertex diameter vs. constant radius consistent, and with that commit the shader works with direct pixel to NDC conversion, however, the NDC conversion factor was outdated in that commit (still included the 0.5 factor for diameter to radius conversion, resulting in all points being 50% narrower along each axis than needed). Now, the diameter to radius conversion factor is used there properly, and also the multiplication of the per-vertex diameter by 0.5 has been removed from the shader since the constant already includes it now (the constant diameter is passed via the system constants instead of the radius also).
The wheel shader in 4D530910 does vfetch_full to r0 with the index from r0.x, and then vfetch_mini.
Thanks @Gliniak for the finding :3
Also small formatting cleanup in commented-out code.
