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[Fix] (DirectVulkan): rewrite implicit-LOD fragment samples to explicit LOD 0 when every bound sampler is pinned to a single mip level - Adreno 650 (driver 512.502) reads outside a full-screen colour render target's allocation on its implicit-LOD sampling path and faults the GPU, which killed MC 26.2 on its own blit shader (texture(InSampler, texCoord)) between frames 344-421 on every run; this is the same driver defect the default-framebuffer blit shader already works around with textureLod, but an application's shader cannot be edited, so ForceExplicitLod0SamplePass converts OpImageSample*ImplicitLod to the explicit form at the SPIR-V level under a new CompileOptionBit that is only requested when the rewrite provably cannot move a texel (every sampler binding on a single-level view, no anisotropy, and either a LOD clamp that already pins lambda at 0 or min and mag filters that agree - an explicit LOD 0 always takes the magnification side of the min/mag decision); a single-level view now also clamps its sampler to mipmapMode NEAREST with maxLod min(maxLod, 0.25) rather than 0, since collapsing the clamp would make every fragment magnify and quietly retire the min filter; and the program's backend hash memo grows from one slot to four so a program resolved under two compile-flag sets in the same frame stops re-hashing every stage's SPIR-V once per draw

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swung0x48
2026-07-29 03:26:57 -04:00
parent 0ea9e6de5f
commit 992d16267c
8 changed files with 356 additions and 25 deletions
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MobileGL/MG_Backend/DirectVulkan/Renderer/VkSamplerManager.cpp
+31 -7
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@@ -51,6 +51,18 @@ namespace MobileGL::MG_Backend::DirectVulkan {
Float ResolveEffectiveMinLod(const MG_State::GLState::SamplerObject& sampler, Float effectiveMaxLod) {
return std::min(sampler.GetMinLod(), effectiveMaxLod);
}
// A single-level view can only ever deliver the base level, but the LOD clamp must not be
// collapsed to exactly 0: both GL and Vulkan pick magFilter over minFilter from the
// *clamped* lambda, so maxLod = 0 would make every fragment magnify and quietly retire the
// min filter. 0.25 is the value VkSamplerCreateInfo's own note prescribes for emulating
// GL's non-mipmapped minification - large enough for lambda to stay positive, small enough
// that a NEAREST mip mode still rounds down to level 0. Clamped rather than assigned, so a
// texture whose GL_TEXTURE_MAX_LOD really is 0 keeps magnifying as GL says it must.
Float ResolveSingleLevelMaxLod(const MG_State::GLState::SamplerObject& sampler, Bool singleLevelView) {
const Float maxLod = ResolveEffectiveMaxLod(sampler);
return singleLevelView ? std::min(maxLod, 0.25f) : maxLod;
}
} // namespace
Bool VkSamplerManager::Initialize(const InitInfo& initInfo) {
@@ -120,11 +132,12 @@ namespace MobileGL::MG_Backend::DirectVulkan {
Uint64 VkSamplerManager::BuildSamplerKey(const MG_State::GLState::SamplerObject& sampler,
const MG_State::GLState::ITextureObject& texture,
Bool forceNearestFiltering) const {
Bool forceNearestFiltering, Bool singleLevelView) const {
MOBILEGL_ASSERT(m_config != nullptr, "VkSamplerManager::BuildSamplerKey: m_config is null");
XXHASH_VERIFY(XXH64_reset(m_hashState, m_config->CacheVersion));
XXHASH_VERIFY(XXH64_update(m_hashState, &forceNearestFiltering, sizeof(forceNearestFiltering)));
XXHASH_VERIFY(XXH64_update(m_hashState, &singleLevelView, sizeof(singleLevelView)));
const auto minFilter = sampler.GetMinFilter();
XXHASH_VERIFY(XXH64_update(m_hashState, &minFilter, sizeof(minFilter)));
@@ -138,7 +151,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
XXHASH_VERIFY(XXH64_update(m_hashState, &wrapT, sizeof(wrapT)));
const auto wrapR = sampler.GetWrapR();
XXHASH_VERIFY(XXH64_update(m_hashState, &wrapR, sizeof(wrapR)));
const auto maxLod = ResolveEffectiveMaxLod(sampler);
const auto maxLod = ResolveSingleLevelMaxLod(sampler, singleLevelView);
const auto minLod = ResolveEffectiveMinLod(sampler, maxLod);
XXHASH_VERIFY(XXH64_update(m_hashState, &minLod, sizeof(minLod)));
XXHASH_VERIFY(XXH64_update(m_hashState, &maxLod, sizeof(maxLod)));
@@ -160,8 +173,17 @@ namespace MobileGL::MG_Backend::DirectVulkan {
VkSampler VkSamplerManager::GetOrCreateSampler(const MG_State::GLState::SamplerObject& sampler,
const MG_State::GLState::ITextureObject& texture,
Bool forceNearestFiltering) {
const Uint64 key = BuildSamplerKey(sampler, texture, forceNearestFiltering);
Bool forceNearestFiltering, Uint32 viewLevelCount) {
// A view that exposes a single mip level has no second level to blend with, so GL's
// *_MIPMAP_* minification filters degenerate to plain filtering on the base level -
// sampling is unchanged by pinning the Vulkan sampler to NEAREST mip mode at LOD 0.
// It is not cosmetic: MobileGL backs such a view with a fully allocated mip chain whose
// tail is never written, and a LINEAR mip mode lets the texture unit issue the level+1
// fetch anyway. On Adreno that fetch lands in uninitialized UBWC pages (or past the
// allocation for a genuinely single-level image) and faults the GPU - the same failure
// the default-framebuffer blit shader had to work around with an explicit-LOD sample.
const Bool singleLevelView = viewLevelCount == 1;
const Uint64 key = BuildSamplerKey(sampler, texture, forceNearestFiltering, singleLevelView);
auto it = m_samplers.find(key);
if (it != m_samplers.end()) {
it->second.lastUsedFrameBoundary = m_frameBoundaryCounter;
@@ -172,8 +194,9 @@ namespace MobileGL::MG_Backend::DirectVulkan {
samplerInfo.sType = VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO;
samplerInfo.magFilter = forceNearestFiltering ? VK_FILTER_NEAREST : ToVkFilter(sampler.GetMagFilter());
samplerInfo.minFilter = forceNearestFiltering ? VK_FILTER_NEAREST : ToVkFilter(sampler.GetMinFilter());
samplerInfo.mipmapMode = forceNearestFiltering ? VK_SAMPLER_MIPMAP_MODE_NEAREST
: ToVkMipmapMode(sampler.GetMipmapMode());
samplerInfo.mipmapMode = (forceNearestFiltering || singleLevelView)
? VK_SAMPLER_MIPMAP_MODE_NEAREST
: ToVkMipmapMode(sampler.GetMipmapMode());
samplerInfo.addressModeU = ToVkAddressMode(sampler.GetWrapS());
samplerInfo.addressModeV = ToVkAddressMode(sampler.GetWrapT());
samplerInfo.addressModeW = ToVkAddressMode(sampler.GetWrapR());
@@ -185,7 +208,8 @@ namespace MobileGL::MG_Backend::DirectVulkan {
samplerInfo.maxAnisotropy = maxAnisotropy;
samplerInfo.compareEnable = sampler.GetCompareMode() == SamplerCompareMode::CompareToTexture ? VK_TRUE : VK_FALSE;
samplerInfo.compareOp = ToVkCompareOp(ResolveCompareFunc(sampler, texture));
samplerInfo.maxLod = ResolveEffectiveMaxLod(sampler);
// Must match BuildSamplerKey's resolution exactly.
samplerInfo.maxLod = ResolveSingleLevelMaxLod(sampler, singleLevelView);
samplerInfo.minLod = ResolveEffectiveMinLod(sampler, samplerInfo.maxLod);
samplerInfo.borderColor = ResolveVkBorderColor(sampler, texture);
samplerInfo.unnormalizedCoordinates = VK_FALSE;