Features

• Implement Shader Model 6.8 min-spec
  • SV_StartInstanceLocation
  • SV_StartVertexLocation
  • WaveSize range
  • Implement Vulkan texturing catch-up features (esoteric comparison sampling functions)
• Implement interop for OpenVR / OpenXR on Proton
• Correctly support NULL index buffers with VK_KHR_maintenance6.
• Implement VK_MESA_image_alignment_control. Reduces memory bloat on AMD cards in particular.

Fixes

• Reimplement VK_NV_low_latency2 to fix some issues with heavy stuttering caused by non-monotonic frame IDs.
  Relies on a more recent dxvk-nvapi which can paper over API design issues in Reflex API.
  Requires a more recent NVIDIA driver which fixes some bugs exposed in this new code.
  On older NVIDIA drivers, it should run, but low-latency will not kick in as expected.
• Explicitly disable variable-rate shading when depth-stencil is written in shader.
  Fixes glitched hair rendering in Hellblade 2.
• Correctly expose MSAA features for depth-stencil. Fixes Arma Reforger.
• Fix bugs in MSAA resolve implementation when dealing with custom resolve formats. Fixes Arma Reforger.
• Fix validation error in internal query resolve shader.
• Fix some bugs in wave-ops where helper lanes participated where they were not supposed to.
  Fixes some WaveMatch / WaveMultiPrefix use-cases in the wild.
• Various dxil-spirv fixes to fix invalid control-flow as always.

Performance

• Tweak how we opt-in to ReBAR for UPLOAD heaps. Now, only > 8 GB cards will get it.
  On 8 GB cards, we were regularly hitting the upper limits of what the GPU could hold in VRAM,
  and using ReBAR would be detrimental to performance since there was risk of more important
  memory being demoted to system memory. Works well together with VK_MESA_image_alignment_control
  to free up significant amounts of VRAM. Performance gains from ReBAR on 8 GB were also found to be minimal
  compared to the larger GPUs since we quickly exhausted the limited 512 MiB budget anyway.
• Sub-allocate small image heaps. Avoids heavy stutter in Ghost of Tsushima on desktop.
  (Steam Deck code path does not seem to use small heaps to begin with).
• Improve performance with ROV when used with more complicated shader code patterns.

Workarounds

• Implement a crude workaround for depth-stencil sparse and MSAA sparse.
  • Just allocates a committed resource instead. Not correct, but good enough band-aid.
  • Allows SottR to run on RADV.
• Disable NV_dgcc on Halo Infinite on NV drivers.
• Workaround a missing barrier in AC: Mirage causing random corrupt geometry.

Misc

• Split vkd3d-proton shader cache up by .exe name when using a unified directory with VKD3D_SHADER_CACHE_PATH.
• Implement VK_EXT_device_address_binding_report.