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.
Fixes the PIX validation warning about missing resource states on every guest draw. Also potentially prevents drivers from making assumptions about the shared memory buffer based on the bindings, though no such cases are currently known.
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.
Make it have no effect on the texture resource as a resource may be used with samplers with different overrides. Also make sure magnification vs. minification is not undefined with it on Direct3D 12.
Float24-as-float32 depth bias is now in the increments of 8, because conversion of the depth to float24 directly in the pixel shaders may destroy the bias qualitatively otherwise if it's too small.
On Vulkan, when snorm16 in unsupported, these formats may be emulated as float16, which natively can represent a wide range of numbers including -32 to 32 with blending. However, R16G16_SNORM and R16G16B16A16_SNORM are two separate formats, which may have different support on the device.
While the alpha of the texture data is not used at all (replaced with blue using the view swizzle), still make the shader code state the intention more explicitly if the format is decompressed for use as signed. Unsigned 1.0 is 0xFF, while signed 1.0 is 0x7F.
The original multiplication was likely added early during the development of generic resolution scaling. Before generic resolution scaling, invocations were done for unscaled guest blocks, now they're done for scaled blocks, so with 3x1 scaling, an invocation for 8 blocks writes 8 host blocks, not 24.
