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[Perf] (MG_Backend): let DirectVulkan's draw fast path survive a VAO swap

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TrySetupDrawFastPath declined on its VAO pointer check for every draw of
a 512-VAO cycle - the Blaze3D chunk-render shape - so the fast path was
dead exactly where it mattered: full SetupDraw, per-draw
ResolveSamplerDescriptor, SyncTextureAndGetDescriptor and render-pass
re-fetch, for draws whose only change was the VAO.

Three fixes. A moved VAO now re-runs only the vertex-input pre-flight
and re-resolves the pipeline instead of declining to the full path. That
resolution probes the value-keyed pipeline memo directly off a cached
pipeline-state hash and snapshot render-pass hash, skipping
GetOrCreateRenderPass and its GetPendingRenderbufferClear probes per
draw; a stale cached hash can only miss, never false-hit. And when the
sampler-descriptor hint holds and the program's single dynamic UBO
re-resolves to the same VkBuffer and range - only the dynamic offset
moved, the per-draw glUniform case - the descriptor walk collapses to
one offset recompute and a vkCmdBindDescriptorSets of the same recorded
set with new pDynamicOffsets. The rebind memo is invalidated at
BeginFrame, layout destruction and override walks; the program lifetime
id never repeats, and per-frame descriptor sets are never rewritten
within their frame.

mc_vanilla_draw -36.9% (1260 -> 795 ns/op, 4.6x native to 3.4x),
sodium_multidraw -18.0%, state_toggle -14.9%, sampler_churn -7.8%,
use_program -7.7%, ubo_range -7.3%, tex_param -7.3%. All nine cases on
both backends, interleaved A/B; no attributable regression. Unit tests
421/421.
This commit is contained in:
BZLZHH
2026-08-06 12:00:31 -04:00
parent b904658b10
commit d0aae85da2
3 changed files with 275 additions and 102 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/UniformManager.h
+46
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@@ -186,6 +186,21 @@ namespace MobileGL::MG_Backend::DirectVulkan {
Bool ResolveUniformBufferPayload(const MG_State::GLState::ProgramObject& program,
const ProgramFactory::VkProgramObject& programObj, Uint32 binding,
Uint32 arrayElement, UboBindResult& out) const;
// Shared resolution of one dynamic-UBO binding element into the
// (buffer, range, dynamicOffset) triple the descriptor consumes: direct
// bind, global-slice reuse, or transient upload. Used by the full walk
// and by the dynamic-offset-only rebind (see FastRebindMemo).
Bool ResolveDynamicUboDescriptor(const MG_State::GLState::ProgramObject& program,
const ProgramFactory::VkProgramObject& programObj, Uint32 binding,
Uint32 arrayElement, Uint32 frameIndex, VkBuffer& outBuffer,
VkDeviceSize& outRange, Uint32& outDynamicOffset);
// The vkCmdBindDescriptorSets tail shared by the full walk and the
// dynamic-offset-only rebind: skips the driver call when this exact
// binding is already live on the command buffer (see the bind-dedup
// shadow below), otherwise binds and refreshes the shadow.
void BindDescriptorSetDeduped(VkCommandBuffer commandBuffer, VkPipelineBindPoint bindPoint,
VkPipelineLayout pipelineLayout, VkDescriptorSet descriptorSet,
const Vector<Uint32>& dynamicOffsets);
Bool CreateDescriptorPool(Uint32 maxSets, VkDescriptorPool& outPool) const;
Bool GrowFrameDescriptorPool(FrameResources& frame, Uint32 frameIndex);
VkResult AllocateDescriptorSetsFromActivePool(
@@ -233,6 +248,37 @@ namespace MobileGL::MG_Backend::DirectVulkan {
DescriptorReuseEntry m_descriptorReuseMemo[kDescriptorReuseMemoSize];
Uint32 m_descriptorReuseMemoNext = 0;
// Dynamic-offset-only rebind (see BindProgramUniformBuffers): records the
// descriptor set selected by the last cacheable full walk of a program
// whose active bindings are exactly one dynamic UBO (single descriptor)
// plus combined-image samplers. When the next call proves every sampler
// descriptor input unchanged (samplerDescriptorsUnchangedHint) and the
// UBO re-resolves to the SAME VkBuffer+range - only the dynamic offset
// moved, the per-draw glUniform case - the walk collapses to: resolve one
// offset, rebind the recorded set with new pDynamicOffsets (Vulkan allows
// rebinding the same set with different dynamic offsets).
// Invalidation inventory: BeginFrame clears it (the frame's sets are
// recycled) and the frameIndex field guards cross-frame confusion on top;
// OnDescriptorSetLayoutDestroyed clears it (the set may be freed); a
// sampler-override walk clears it (mirrors m_descriptorReuseMemo); a
// program relink bumps the backend state version and thus programObj.hash
// so the key misses; the program lifetime id is never reused, so a
// deleted-and-recreated program misses; a texture/sampler/binding change
// drops the hint upstream; an arena wrap or growth resolves a different
// VkBuffer and misses. AcquireDescriptorSet's per-frame cursor only
// advances, so the recorded set is never re-written within its frame.
struct FastRebindMemo {
Bool valid = false;
Uint32 frameIndex = 0;
Uint64 programLifetimeId = 0;
ProgramFactory::HashType programHash = 0;
Uint32 uboBinding = 0;
VkBuffer uboBuffer = VK_NULL_HANDLE;
VkDeviceSize uboRange = 0;
VkDescriptorSet set = VK_NULL_HANDLE;
};
FastRebindMemo m_fastRebindMemo;
// vkCmdBindDescriptorSets dedup: consecutive draws with a static uniform
// block resolve to the same set AND the same dynamic offsets, so the
// driver call can be skipped outright. Command-buffer-scope state; reset