Similar to constant redundant synchronization for textures, there is a lot of redundant synchronization of buffers. Albeit, buffer synchronization is far cheaper than texture synchronization it still has associated costs which have now been reduced by only synchronizing on access.
There was a lot of redundant synchronization of textures to and from host constantly as we were not aware of guest memory access, this has now been averted by tracking any memory accesses to the texture memory using the NCE Memory Trapping API and synchronizing only when required.
An API for trapping accesses to guest memory and performing callbacks based on those accesses alongside managing protection of the memory. This is a fundamental building block for avoiding redundant synchronization of resources from the guest and host.
Note: All accesses are treated as write accesses at the moment, support for picking up read accesses will be implemented later
An interval map is a crucial piece of infrastructure required for memory faulting to track any regions that have an associated callback and their protection. Additionally, efficient page-aligned lookups with semantics optimal for memory faulting are also a requirement and the ability to associate multiple regions with a single callback/protection entry rather than doing so on a per-region basis as we deal with split-mapping resources.
This is a prerequisite to memory trapping as we need to write to the mirror to avoid a race condition with external threads writing to a texture/buffer while we do so ourselves for the sync on a read/write, it also avoids an additional `mprotect` to `-WX`/`RWX` on a read access.
An additional advantage for textures especially is that we now support split-mapping textures due to laying them out in a contiguous mirror and they will not require costly algorithmic changes. Buffers should also benefit from not needing to iterate over every region when they are split into multiple mappings.
`CreateMirror` is limited to creating a mirror of a single contiguous region which does not work when creating a contiguous mirror of multiple non-contiguous regions. To support this functionality, `CreateMirrors` which expects a list of page-aligned regions and maps them into a contiguous mirror.
We want to create arbitrary mirrors in the guest address space and to make this possible, we map the entire address space as a shared memory file. A mirror is mapped by using `mmap` with the offset into the guest address space.
Previously for methods with count > 1 the subchannel and engine would be looked up for each part of the method rather than only doing so at the start. Each call also needed to be looked up to see if it touched a macro or GPFIFO method. Fix this by doing checks outside of the main dispatch loop with templated helper lambdas to avoid needing to repeat lots of code. Maxwell3D is the only subchannel with a fast path for now but more can be added later if needed.
Almost every Maxwell format now directly corresponds to a Vulkan format. This allows formats to be passed through and the swizzle used directly from guest (with some extra swizzle handling for edge cases) thus saving the need to explicitly support each swizzle combination which is adds a lot of code bloat. The format header is additionally reordered with line breaks to separate formats by their bits-per-block.
We always submit pipeline divisor descriptions regardless of binding input rate being vertex rather than instance. This is invalid behavior and has been fixed by only submitting binding descriptors when the input rate is per-instance.
Adreno proprietary drivers suffer from a bug where `VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER` requires 2 descriptor slots rather than one, we add a padding slot to fix this issue. `QuirkManager` was introduced to handle per-vendor/per-device errata and allow enabling this on Adreno proprietary drivers specifically as to not affect the performance of other devices.
Quirk terminology was deemed to be inappropriate for describing the features/extensions of a device. It has been replaced with traits which is far more fitting but quirks will be used as a terminology for errata in devices.
The texture handle offset calculation involved an incorrect shift by descriptor size which was found to be unnecessary and would result in an invalid handle that had the wrong TIC/TSC index and caused broken rendering.
`nodes` and `syncTextures` were cleared after waiting on the `CommandExecutor` fence rather than before, this wasted execution time after the wait for something that could be performed prior to the wait.
We now attempt to enable `VK_KHR_uniform_buffer_standard_layout` when present as lax UBO layout significantly reduces complexity. If a device doesn't support this extension, we still assume that the device supports it implicitly as this has proven to be true across all major mobile GPU vendors regardless of the driver version but enabling this prevents validation layer errors.
We depend on past commands to have completed execution in a renderpass, a subpass dependency on all graphics stages from `VK_SUBPASS_EXTERNAL` to subpass #0 is used to enforce this. Nvidia and Adreno proprietary drivers implicitly do this but Turnip or Mali drivers require this or they execute out of order.
Blocklinear texture decoding was broken for padding blocks and would incorrectly decode them resulting in major texture corruption for any textures with their widths not aligned to 64 bytes. This has now been fixed with neater code which avoids redundant repetition of any code using lambdas and functions where necessary.
Stencil operations are configurable to be the same for both sides or have independent stencil state for both sides. It is controlled via the previously unimplemented `stencilTwoSideEnable`.
Fermi2D supports macros in addition to Maxwell3D, these both share code memory. To support this we rework the macro interpreter to support passing in a target engine and abstract the communications out into an interface that can be implemented by applicable engines.
```
GPFIFO <-> MME <-> Maxwell3D
^ ^---> Fermi2D
X------------> I2M
X------------> MaxwellComputeB
X--Flush-----> MaxwellDMA
```
Shader programs allocate instructions and blocks within an `ObjectPool`, there was a global pool prior that was never reaped aside from on destruction. This led to a leak where the pool would contain resources from shader programs that had been deleted, to avert this the pools are now tied to shader programs.
The size of blocklinear textures did not consider alignment to Block/ROB boundaries before, it is aligned to them now. Incorrect sizes led to textures not being aliased correctly due to different size calculations for GraphicBufferProducer surfaces and Maxwell3D color RTs.
erase invalidated `it` leading to a potential segfault if the GPU was very far behind, bail out early to avoid that since there can only be one occurence at most in the buffer anyway.
Implements the entirety of Maxwell3D Depth/Stencil state for both faces including compare/write masks and reference value. Maxwell3D register `stencilTwoSideEnable` is ignored as its behavior is unknown and could mean the same behavior for both stencils or the back facing stencil being disabled as a result of this it is unimplemented.
We don't respect the host subresource layout in synchronizing linear textures from the guest to the host when mapped to memory directly, this leads to texture corruption and while the real fix would involve respecting the host subresource layout, this has been deferred for later as real world performance advantages/disadvantages associated with this change can be observed more carefully to determine if it's worth it.
