BindProgramUniformBuffers rebuilt a fresh descriptor set and called
vkUpdateDescriptorSets on every draw, even when consecutive draws bound the exact
same textures/samplers/buffers (common in MC: many draws share a program + atlas).
Now, after resolving the bindings (still needed for the UBO dynamic offset),
compute a cheap word-wise signature of the resolved descriptor content + layout;
when it matches the previous draw, reuse that descriptor set and skip
AcquireDescriptorSet + vkUpdateDescriptorSets - only the bind-time dynamic offsets
differ.
Correct by construction: bindings are re-resolved every draw so the signature
always reflects current state and reuse only happens on an exact match; the reused
set is never re-acquired within a frame (the acquire cursor only advances); the
descriptor set layout is in the signature so reuse never crosses programs; the
cache resets each frame in BeginFrame when the frame's sets are recycled; sampler
overrides (blits) bypass and invalidate it. The signature hashes 64-bit words (the
Vk*Info payloads are 8-byte-multiple sized and value-initialized) so its own
per-draw cost stays small.
Device-verified on Adreno 830 (MC 26.3-snapshot3, optimized -O2 Magma): rendering
correct, no validation errors. Render-thread wall-clock profile:
BindProgramUniformBuffers 22.85% -> 19.82% (vkUpdateDescriptorSets ~5% dropped below
noise; word-wise signature adds ~0.6% self), SetupDraw 62% -> 60%.
- Memoize the program content hash on ProgramObject (keyed by the backend
state version + compile flags; relinking and binding changes invalidate
it) and the vertex-input hash on VertexArrayObject (keyed by a new
aggregate config version bumped by every attribute mutation). Full-SPIRV
XXH64 hashing fell from 13.7% to 1.4% of the render thread.
- ProgramObject also gains a link version and a global-UBO content version
(bumped by uniform writes and on relink, wrap-safe around the backends'
"never uploaded" sentinel) for backends to gate uploads and link caches.
- Reuse member scratch vectors in SetupDraw, UploadAndBindVertexBuffers,
GetOrCreatePipeline and BindProgramUniformBuffers instead of allocating
per draw (~12% of render-thread time was in the allocator).
- Replace hot-path dynamic_cast with AsMipmapTexture (storage-type tag +
static_cast); TextureObjectMipmap is the only Mipmap-tagged branch.
- Register/prune texture aliases only when a new (texture, lifetimeId)
identity appears instead of scanning the entire alive map on every
sampled-texture sync.
- Make the fallback VkPresentModeKHR log strings report the actual mode.
Vanilla render-thread share of libMobileGL dropped from 48% to 35% on
DirectVulkan (simpleperf, Adreno 830).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
- Support cube map face uploads with cube-compatible images and per-face array layers
- Add uniform texel buffer descriptor support for samplerBuffer bindings
- Cache transient vertex/index buffer uploads per frame to avoid VMA allocation failures
swung0x48
