graphics: bind unbound textures as native null descriptors

src/graphics/host_gpu/renderer/cache/textureCache.cpp

@@ -199,9 +199,7 @@ TextureCache::BindingType TextureCache::UploadBinding(const Image& image) {
 
 ImageId TextureCache::InsertImage(const ImageInfo& info) {
 	const auto id = m_slot_images.insert(m_graphics, m_scheduler, info);
-	if (!info.data.Empty()) {
-		RegisterImage(id);
-	}
+	RegisterImage(id);
 	return id;
 }
 
@@ -408,7 +406,7 @@ void TextureCache::UntrackImageTail(ImageId id) {
 }
 
 void TextureCache::TrackImageDownload(ImageId id, Image& image) {
-	if (m_readback_linear_images && !image.info.IsTiled() && !image.info.data.Empty()) {
+	if (m_readback_linear_images && !image.info.IsTiled()) {
 		if (!image.IsGpuModified()) {
 			EXIT("TextureCache: cannot enroll a non-GPU-owned image for download\n");
 		}
@@ -452,27 +450,6 @@ TextureCache::ImageIds TextureCache::FindImagesInRegion(uint64_t address, uint64
 	return result;
 }
 
-ImageId TextureCache::GetNullImage(const ImageDesc& desc) {
-	const auto format = desc.info.pixel_format;
-	if (const auto found = m_null_images.find(format); found != m_null_images.end()) {
-		return found->second;
-	}
-	ImageInfo info {};
-	info.pixel_format    = desc.info.pixel_format;
-	info.guest_format    = desc.info.guest_format;
-	info.type            = Prospero::ImageType::kColor2D;
-	info.extent          = {1, 1, 1};
-	info.resources       = {1, 1};
-	info.pitch           = 1;
-	info.bytes_per_block = std::max(desc.info.bytes_per_block, 1u);
-	info.samples         = 1;
-	info.tile_mode       = Prospero::TileMode::kLinear;
-	info.mip_layout[0]   = {0, info.bytes_per_block, 1, 1};
-	const auto id        = InsertImage(info);
-	m_null_images.emplace(format, id);
-	return id;
-}
-
 void TextureCache::ValidateImageDesc(const ImageDesc& desc) const {
 	ImageOps::Validate(desc.info);
 	if (desc.view_info.format == vk::Format::eUndefined || desc.view_info.level_count == 0 ||
@@ -1026,9 +1003,6 @@ void TextureCache::UploadImage(Image& image, Buffer& source, uint64_t source_off
 
 void TextureCache::InitializeImage(ImageId id) {
 	auto& image = m_slot_images[id];
-	if (image.info.data.Empty()) {
-		return;
-	}
 	TrackImage(id);
 	if (image.info.metadata.compression != VideoOutCompression::Uncompressed) {
 		if (image.IsCpuDirty()) {
@@ -1215,10 +1189,7 @@ ImageId TextureCache::FindImage(ImageDesc& desc, bool exact_format) {
 		EXIT("TextureCache: image lookup requires a valid command buffer\n");
 	}
 	ValidateImageDesc(desc);
-	if (desc.info.data.Empty()) {
-		std::scoped_lock lock {m_lock};
-		return GetNullImage(desc);
-	}
+	EXIT_IF(desc.info.data.Empty());
 	const auto metadata_base_layer = desc.view_info.base_layer;
 
 	ImageId result {};
@@ -1370,36 +1341,30 @@ vk::ImageView TextureCache::FindTexture(ImageId id, const ImageDesc& desc) {
 	std::scoped_lock lock {m_lock};
 	auto&            image = m_slot_images[id];
 	TouchImage(image);
-	if (!image.info.data.Empty()) {
-		if (!image.registered || image.depth_id || image.binding.needs_rebind) {
-			EXIT("TextureCache: texture requires rediscovery before final acquisition\n");
-		}
+	if (!image.registered || image.depth_id || image.binding.needs_rebind) {
+		EXIT("TextureCache: texture requires rediscovery before final acquisition\n");
 	}
 	if (desc.type == BindingType::Storage) {
 		image.MarkGpuModified();
 	}
-	if (!image.info.data.Empty()) {
-		RefreshImage(id);
-		if (image.info.HasStencil() &&
-		    desc.info.data.address >= image.info.stencil.address &&
-		    desc.info.data.End() <= image.info.stencil.End()) {
-			for (const auto stencil_id:
-			     FindImagesInRegion(image.info.stencil.address, image.info.stencil.size, false)) {
-				const auto* stencil = m_slot_images.try_get(stencil_id);
-				if (stencil != nullptr && stencil->depth_id == id &&
-				    stencil->info.data == image.info.stencil) {
-					RefreshImage(stencil_id);
-					break;
-				}
+	RefreshImage(id);
+	if (image.info.HasStencil() &&
+	    desc.info.data.address >= image.info.stencil.address &&
+	    desc.info.data.End() <= image.info.stencil.End()) {
+		for (const auto stencil_id:
+		     FindImagesInRegion(image.info.stencil.address, image.info.stencil.size, false)) {
+			const auto* stencil = m_slot_images.try_get(stencil_id);
+			if (stencil != nullptr && stencil->depth_id == id &&
+			    stencil->info.data == image.info.stencil) {
+				RefreshImage(stencil_id);
+				break;
 			}
 		}
 	}
 	switch (desc.type) {
 		case BindingType::Texture: break;
 		case BindingType::Storage:
-			if (!image.info.data.Empty()) {
-				CommitGpuWrite(image);
-			}
+			CommitGpuWrite(image);
 			TrackImageDownload(id, image);
 			break;
 		default: EXIT("TextureCache: invalid texture binding\n");

src/graphics/host_gpu/renderer/cache/textureCache.h

@@ -14,7 +14,6 @@
 
 #include <map>
 #include <type_traits>
-#include <unordered_map>
 #include <unordered_set>
 #include <vector>
 
@@ -114,7 +113,6 @@ private:
 	}
 
 	[[nodiscard]] ImageId     InsertImage(const ImageInfo& info);
-	[[nodiscard]] ImageId     GetNullImage(const ImageDesc& desc);
 	void                      RegisterImage(ImageId id);
 	void                      UnregisterImage(ImageId id);
 	void                      DeleteImage(ImageId id);
@@ -173,7 +171,6 @@ private:
 	BufferCache&                                      m_buffer_cache;
 	Common::SlotVector<Image>                         m_slot_images;
 	ImagePageTable                                    m_image_page_table;
-	std::unordered_map<vk::Format, ImageId>           m_null_images;
 	Common::LeastRecentlyUsedCache<ImageId, uint64_t> m_lru_cache;
 	std::unordered_set<ImageId>                       m_download_images;
 	std::map<uint64_t, MetaDataInfo>                  m_surface_metas;

src/graphics/host_gpu/renderer/pipeline/descriptors.cpp

@@ -76,6 +76,10 @@ vk::DescriptorType NativeDescriptorType(BindingKind kind) {
 }
 
 vk::DescriptorImageInfo MakeImageInfo(const TextureBinding& texture, uint32_t element) {
+	if (!texture.image_id) {
+		EXIT_IF(texture.image_view != nullptr || !texture.mip_views.empty());
+		return {nullptr, nullptr, vk::ImageLayout::eGeneral};
+	}
 	vk::ImageView view = nullptr;
 	if (texture.mip_views.empty()) {
 		if (element == 0u) {
@@ -84,7 +88,7 @@ vk::DescriptorImageInfo MakeImageInfo(const TextureBinding& texture, uint32_t el
 	} else if (element < texture.mip_views.size()) {
 		view = texture.mip_views[element];
 	}
-	EXIT_IF(!texture.image_id || view == nullptr || texture.layout == vk::ImageLayout::eUndefined);
+	EXIT_IF(view == nullptr || texture.layout == vk::ImageLayout::eUndefined);
 	return {nullptr, view, texture.layout};
 }
 
@@ -348,39 +352,6 @@ void ValidateStorageTexture(const ShaderRecompiler::IR::ImageResource& resource,
 	     descriptor.fields[5], descriptor.fields[6], descriptor.fields[7]);
 }
 
-static TextureCache::ImageDesc NullTextureDesc(const ShaderRecompiler::IR::ImageResource& resource,
-                                               TextureCache::BindingType                  binding) {
-	TextureCache::ImageDesc desc {};
-	switch (resource.numeric_class) {
-		case Prospero::TextureNumericClass::Float:
-			desc.info.guest_format = Prospero::BufferFormat::k32Float;
-			break;
-		case Prospero::TextureNumericClass::Uint:
-			desc.info.guest_format = resource.atomic64 ? Prospero::BufferFormat::k32_32UInt
-			                                         : Prospero::BufferFormat::k32UInt;
-			break;
-		case Prospero::TextureNumericClass::Sint:
-			desc.info.guest_format = Prospero::BufferFormat::k32SInt;
-			break;
-		default: EXIT("null image has unsupported numeric class\n");
-	}
-	desc.info.pixel_format    = VulkanFormat(desc.info.guest_format);
-	desc.info.type            = Prospero::ImageType::kColor2D;
-	desc.info.extent          = {1, 1, 1};
-	desc.info.resources       = {1, 1};
-	desc.info.bytes_per_block = Prospero::NumBytesPerElement(desc.info.guest_format);
-	desc.info.samples         = 1;
-	desc.info.mip_layout[0]   = {0, 0, 1, 1};
-	desc.view_info.format     = resource.atomic64 ? vk::Format::eR64Uint : desc.info.pixel_format;
-	desc.view_info.type       = vk::ImageViewType::e2D;
-	desc.view_info.aspect     = vk::ImageAspectFlagBits::eColor;
-	desc.view_info.usage      = binding == TextureCache::BindingType::Storage
-	                                ? vk::ImageUsageFlagBits::eStorage
-	                                : vk::ImageUsageFlagBits::eSampled;
-	desc.type                 = binding;
-	return desc;
-}
-
 static ImageViewInfo TextureViewInfo(const ShaderRecompiler::IR::ImageResource& resource,
                                      const ShaderTextureResource& descriptor, vk::Format format,
                                      const SurfaceFormatInfo& surface_format, bool storage,
@@ -516,10 +487,7 @@ TextureBinding RenderExecutor::ResolveTexture(const ShaderRecompiler::IR::ImageR
 
 	auto& texture_cache = m_context.GetTextureCache();
 	if (descriptor.IsNull()) {
-		auto       desc = NullTextureDesc(resource, storage ? TextureCache::BindingType::Storage
-		                                                    : TextureCache::BindingType::Texture);
-		const auto id   = texture_cache.FindImage(desc);
-		return {id, nullptr, std::move(desc)};
+		return {.layout = vk::ImageLayout::eGeneral};
 	}
 
 	const auto address         = descriptor.Base40();
@@ -689,10 +657,10 @@ static vk::DescriptorBufferInfo NativeUpload(RenderContext&            context,
 }
 
 void RenderExecutor::BindImage(ImageId id, bool storage) {
-	auto& image = m_context.GetTextureCache().GetImage(id);
-	if (image.info.data.Empty()) {
+	if (!id) {
 		return;
 	}
+	auto& image = m_context.GetTextureCache().GetImage(id);
 	if (image.binding.is_bound) {
 		image.binding.force_general |= image.binding.shader_write != storage;
 	}
@@ -845,8 +813,9 @@ void RenderExecutor::RebindImages(PreparedBindings& prepared) {
 	auto& texture_cache = m_context.GetTextureCache();
 	// Acquire each view before a later overlapping descriptor can replace its image.
 	for (uint32_t i = 0; i < program.info.images.size(); i++) {
+		if (!images[i].image_id) continue;
 		const auto old_image = texture_cache.m_slot_images.try_get(images[i].image_id);
-		if (old_image == nullptr || (!old_image->registered && !old_image->info.data.Empty()) ||
+		if (old_image == nullptr || !old_image->registered ||
 		    old_image->binding.needs_rebind) {
 			if (old_image != nullptr) {
 				old_image->binding = {};
@@ -897,7 +866,7 @@ void RenderExecutor::PrepareGraphicsBindings(std::span<PreparedBindings* const>
 	for (auto& target: colors) {
 		EXIT_IF(!target.image_id);
 		const auto old_image = cache.m_slot_images.try_get(target.image_id);
-		if (old_image == nullptr || (!old_image->registered && !old_image->info.data.Empty()) ||
+		if (old_image == nullptr || !old_image->registered ||
 		    old_image->binding.needs_rebind) {
 			if (old_image != nullptr) {
 				old_image->binding = {};
@@ -1007,19 +976,14 @@ void RenderExecutor::CommitBindings(CommandBuffer&                     buffer,
 		}
 
 		for (uint32_t i = 0; i < program.info.images.size(); i++) {
-			auto& image   = m_context.GetTextureCache().GetImage(descriptors.images[i].image_id);
 			auto& binding = descriptors.images[i];
+			if (!binding.image_id) continue;
+			auto& image = m_context.GetTextureCache().GetImage(binding.image_id);
 			const auto&                 view = binding.desc.view_info;
 			const ImageSubresourceRange range {view.base_level, view.level_count, view.base_layer,
 			                                   view.layer_count};
 			const bool storage = binding.desc.type == TextureCache::BindingType::Storage;
-			if (image.info.data.Empty()) {
-				image.Transit(vk::ImageLayout::eGeneral,
-				              storage ? vk::AccessFlagBits2::eShaderRead |
-				                            vk::AccessFlagBits2::eShaderWrite
-				                      : vk::AccessFlagBits2::eShaderRead,
-				              range, vk_buffer);
-			} else if (image.binding.is_target) {
+			if (image.binding.is_target) {
 				const auto layout = image.binding.attachment_layout;
 				EXIT_IF(layout == vk::ImageLayout::eUndefined);
 				if (image.info.IsDepth()) {
@@ -1120,7 +1084,8 @@ void RenderExecutor::CommitBindings(CommandBuffer&                     buffer,
 		for (uint32_t i = 0; i < program.info.images.size(); ++i) {
 			const auto& resource = program.info.images[i];
 			const auto& texture = descriptors.images[i];
-			EXIT_IF(resource.mip_count != (texture.mip_views.empty() ? 1u : texture.mip_views.size()));
+			EXIT_IF(texture.image_id &&
+			        resource.mip_count != (texture.mip_views.empty() ? 1u : texture.mip_views.size()));
 			const auto kind = *ShaderRecompiler::IR::DescriptorBindingForImage(resource);
 			const auto start = image_starts[ShaderRecompiler::IR::ImageBindingIndex(kind)] +
 			                   resource.descriptor_index;

src/graphics/presentation/window/vulkanWindow.cpp

@@ -216,6 +216,7 @@ static void VulkanFindPhysicalDevice(vk::Instance instance, vk::SurfaceKHR surfa
 
 		vk::PhysicalDeviceVulkan12Features features12 {};
 		vk::PhysicalDeviceVulkan11Features features11 {};
+		vk::PhysicalDeviceRobustness2FeaturesEXT robustness2 {};
 #if defined(__APPLE__)
 		features12.pNext = &depth_clip_control;
 #else
@@ -223,7 +224,8 @@ static void VulkanFindPhysicalDevice(vk::Instance instance, vk::SurfaceKHR surfa
 		fragment_barycentric.pNext = &depth_clip_control;
 		features12.pNext           = &fragment_barycentric;
 #endif
-		features11.pNext       = features12.pNext;
+		robustness2.pNext      = features12.pNext;
+		features11.pNext       = &robustness2;
 		features12.pNext       = &features11;
 		features13.pNext       = &features12;
 		device_features2.pNext = &features13;
@@ -289,6 +291,7 @@ static void VulkanFindPhysicalDevice(vk::Instance instance, vk::SurfaceKHR surfa
 		              "shaderStorageBufferArrayNonUniformIndexing",
 		              required_features12.shaderStorageBufferArrayNonUniformIndexing);
 		check_feature(features13.robustImageAccess, "robustImageAccess");
+		check_feature(robustness2.nullDescriptor, "nullDescriptor");
 		check_feature(features13.dynamicRendering, "dynamicRendering",
 		              required_features13.dynamicRendering);
 		check_feature(features13.synchronization2, "synchronization2",
@@ -450,14 +453,9 @@ static vk::Device VulkanCreateDevice(GraphicContext& graphics,
 	vk::PhysicalDeviceVulkan13Features supported_features13 {};
 	supported_features13.pNext = &supported_features12;
 
-	const auto robustness2_ext_enabled =
-	    HasExtension(device_extensions, VK_EXT_ROBUSTNESS_2_EXTENSION_NAME);
-
 	vk::PhysicalDeviceRobustness2FeaturesEXT supported_robustness2 {};
-	if (robustness2_ext_enabled) {
-		supported_robustness2.pNext = supported_features13.pNext;
-		supported_features13.pNext = &supported_robustness2;
-	}
+	supported_robustness2.pNext = supported_features13.pNext;
+	supported_features13.pNext = &supported_robustness2;
 
 	const bool mesh_extension = HasExtension(device_extensions, VK_EXT_MESH_SHADER_EXTENSION_NAME);
 	vk::PhysicalDeviceMeshShaderFeaturesEXT supported_mesh {};
@@ -611,27 +609,19 @@ static vk::Device VulkanCreateDevice(GraphicContext& graphics,
 	fragment_barycentric.fragmentShaderBarycentric = VK_TRUE;
 	robustness2.pNext                              = &fragment_barycentric;
 #endif
-	if (robustness2_ext_enabled) {
-		robustness2.robustBufferAccess2 = supported_robustness2.robustBufferAccess2;
-		robustness2.robustImageAccess2  = supported_robustness2.robustImageAccess2;
-		robustness2.nullDescriptor      = supported_robustness2.nullDescriptor;
-	}
+	robustness2.robustBufferAccess2 = supported_robustness2.robustBufferAccess2;
+	robustness2.robustImageAccess2  = supported_robustness2.robustImageAccess2;
+	robustness2.nullDescriptor      = VK_TRUE;
 
 	auto features13 = WindowContext::RequiredVulkan13Features();
-#if defined(__APPLE__)
-	features13.pNext = robustness2_ext_enabled ? static_cast<void*>(&robustness2)
-	                                           : static_cast<void*>(&features12);
-#else
-	features13.pNext = robustness2_ext_enabled ? static_cast<void*>(&robustness2)
-	                                           : static_cast<void*>(&fragment_barycentric);
-#endif
+	features13.pNext = &robustness2;
 	features13.robustImageAccess   = supported_features13.robustImageAccess;
 	features13.subgroupSizeControl =
 	    graphics.compute_subgroup_size_control_enabled ? VK_TRUE : VK_FALSE;
 
 	LOGF("Vulkan robustness: robustImageAccess=%s robustImageAccess2=%s\n",
 	     features13.robustImageAccess == VK_TRUE ? "true" : "false",
-	     robustness2_ext_enabled && robustness2.robustImageAccess2 == VK_TRUE ? "true" : "false");
+	     robustness2.robustImageAccess2 == VK_TRUE ? "true" : "false");
 
 	vk::DeviceCreateInfo create_info {};
 	vk::PhysicalDeviceMeshShaderFeaturesEXT mesh_features {};
@@ -961,7 +951,7 @@ void WindowContext::CreateVulkan() {
 	std::vector<const char*> device_extensions = {
 	    VK_KHR_SWAPCHAIN_EXTENSION_NAME, VK_EXT_DEPTH_CLIP_CONTROL_EXTENSION_NAME,
 	    VK_EXT_IMAGE_VIEW_MIN_LOD_EXTENSION_NAME, VK_KHR_PUSH_DESCRIPTOR_EXTENSION_NAME,
-	    "VK_KHR_maintenance1"};
+	    VK_EXT_ROBUSTNESS_2_EXTENSION_NAME, "VK_KHR_maintenance1"};
 
 #if defined(__APPLE__)
 	// MoltenVK lacks VK_EXT_depth_clip_enable and VK_EXT_color_write_enable; the renderer
@@ -1024,8 +1014,7 @@ void WindowContext::CreateVulkan() {
 			device_extensions.push_back(VK_EXT_MEMORY_BUDGET_EXTENSION_NAME);
 			graphic_ctx.memory_budget_ext_enabled = true;
 		}
-		for (const auto* extension: {VK_EXT_ROBUSTNESS_2_EXTENSION_NAME,
-		                             VK_KHR_MAINTENANCE_8_EXTENSION_NAME,
+		for (const auto* extension: {VK_KHR_MAINTENANCE_8_EXTENSION_NAME,
 		                             VK_EXT_SHADER_IMAGE_ATOMIC_INT64_EXTENSION_NAME,
 		                             VK_EXT_PROVOKING_VERTEX_EXTENSION_NAME,
 		                             VK_EXT_MESH_SHADER_EXTENSION_NAME,

tests/ShaderRecompilerComputeTests.cpp

@@ -356,10 +356,6 @@ struct TextureCacheTestAccess {
     return cache.m_download_images.contains(id);
   }
 
-  static size_t NullImageCount(const TextureCache &cache) {
-    return cache.m_null_images.size();
-  }
-
   static void TrackDownload(TextureCache &cache, ImageId id) {
     std::lock_guard lock(cache.m_lock);
     cache.TrackImageDownload(id, cache.m_slot_images[id]);
@@ -10376,6 +10372,110 @@ public:
     return result;
   }
 
+  void CheckNullTextureDescriptors() {
+    constexpr const char *name = "NullTextureDescriptors";
+    constexpr uintptr_t base = 0x0000000204900000ull;
+    constexpr uint64_t size = 0x10000;
+    std::vector<u32> reader{
+        EncodeVop2(0x1a, 20, InlineU32(5), 0),
+        EncodeVop1(0x01, 21, InlineU32(0)),
+        EncodeVop1(0x01, 22, InlineU32(0)),
+        EncodeMimg0(0x00, 0xf), EncodeMimg1(1, 21)};
+    AppendVMovLiteral(&reader, 23, std::bit_cast<u32>(0.5f));
+    AppendVMovLiteral(&reader, 24, std::bit_cast<u32>(0.5f));
+    reader.insert(reader.end(), {
+        EncodeMimg0(0x27, 0xf), EncodeMimg1(5, 23, 0, 2),
+        0xbf8c3f70u,
+        EncodeMubuf0(0x1e), EncodeMubuf1(1, 3, 20),
+        EncodeMubuf0(0x1e, 16), EncodeMubuf1(5, 3, 20)});
+    AppendEnd(&reader);
+    std::vector<u32> writer{
+        EncodeVopc(0xd2, InlineU32(0), 0),
+        EncodeVop1(0x01, 21, InlineU32(0)),
+        EncodeVop1(0x01, 22, InlineU32(0))};
+    for (u32 i = 1; i <= 4; ++i)
+      AppendVMovLiteral(&writer, i, std::bit_cast<u32>(-1000000.0f));
+    writer.insert(writer.end(), {EncodeMimg0(0x08, 0xf), EncodeMimg1(1, 21)});
+    AppendEnd(&writer);
+    for (const auto *code : {&reader, &writer})
+      ShaderMapUserData(reinterpret_cast<uint64_t>(code->data()),
+          {.type = Prospero::ShaderBinaryType::kCs,
+           .code_size_bytes = static_cast<u32>(code->size() * sizeof(u32))});
+
+    EnsureRuntimeContext();
+    int64_t physical = -1;
+    Require(name, "allocate", LibKernel::Memory::KernelAllocateDirectMemory(
+        0, LibKernel::Memory::KernelGetDirectMemorySize(), size, size, 0, &physical) == 0,
+        "null texture output allocation failed");
+    void *mapped = reinterpret_cast<void *>(base);
+    Require(name, "map", LibKernel::Memory::KernelMapDirectMemory(
+        &mapped, size, 0x3, 0x10, physical, size) == 0 && mapped == reinterpret_cast<void *>(base),
+        "null texture output mapping failed");
+    std::memset(mapped, 0xa5, size);
+    RenderContext context(m_runtime_context);
+    context.InitializeGpu(nullptr);
+    LibKernel::Memory::InstallGpuResources(&context);
+    context.GetGpu().SendCommandSync([&] {
+      CommandProcessor processor(context, 0);
+      processor.BufferInit();
+      context.MapMemory(base, size);
+      auto &shaders = processor.GetShCtx();
+      auto &executor = context.GetRenderExecutor();
+      for (u32 wave_size : {32u, 64u}) {
+        const auto output_address = [&](u32 phase) {
+          return base + (wave_size == 64 ? 0x8000u : 0u) + 0x100u + phase * 0x2000u;
+        };
+        for (u32 sgpr = 0; sgpr < 16; ++sgpr)
+          shaders.SetCsUserSgpr(sgpr, 0, HW::UserSgprType::Unknown);
+        shaders.SetCsUserSgpr(8, 0x92u, HW::UserSgprType::Unknown);
+        for (u32 phase = 0; phase < 3; ++phase) {
+          const auto &code = phase == 1 ? writer : reader;
+          shaders.SetCsShader({.data_addr = reinterpret_cast<uint64_t>(code.data()),
+                               .num_thread_x = wave_size, .num_thread_y = 1, .num_thread_z = 1,
+                               .wave_size = static_cast<uint8_t>(wave_size), .user_sgpr = 16});
+          ShaderBufferResource output{};
+          output.UpdateAddress48(output_address(phase));
+          output.fields[2] = wave_size * 8u * sizeof(u32);
+          output.fields[3] = DstSel(4, 5, 6, 7) |
+              (static_cast<u32>(Prospero::BufferFormat::k32UInt) << 12u);
+          for (u32 i = 0; i < 4; ++i)
+            shaders.SetCsUserSgpr(12 + i, output.fields[i], HW::UserSgprType::Unknown);
+          ShaderComputeInputInfo input{};
+          (void)context.GetPipelineCache().GetComputeProgram(
+              shaders.GetCs(), processor.GetCtx().GetShaderRegisters(), input);
+          PreparedBindings bindings;
+          executor.PrepareBindings(input.stage, bindings);
+          executor.RebindImages(bindings);
+          Require(name, "native null image bindings", !bindings.images.empty() &&
+              std::ranges::all_of(bindings.images, [](const auto &binding) {
+                return !binding.image_id && binding.image_view == nullptr &&
+                    binding.mip_views.empty() &&
+                    MakeImageInfo(binding).imageView == nullptr &&
+                    binding.layout == vk::ImageLayout::eGeneral;
+              }), "an all-zero guest descriptor allocated or bound a backing image");
+          processor.DispatchDirect(1, 1, 1, 0x41u);
+        }
+        for (u32 phase : {0u, 2u}) {
+          const auto address = output_address(phase);
+          std::vector<u32> actual(wave_size * 8u);
+          context.GetBufferCache().ReadMemory(address, actual.size() * sizeof(u32));
+          Require(name, "null RGBA before and after storage write",
+              LibKernel::Memory::TryReadBacking(address, actual.data(), actual.size() * sizeof(u32)) &&
+                  std::ranges::all_of(actual, [](u32 value) { return value == 0; }),
+              "wave" + std::to_string(wave_size) + " phase" + std::to_string(phase) +
+                  " returned nonzero load/sample components from an unbound texture");
+        }
+      }
+      context.UnmapMemory(base, size);
+      context.GetCommandScheduler().Finish();
+    });
+    LibKernel::Memory::InstallGpuResources(nullptr);
+    context.ShutdownGpu();
+    Require(name, "release", LibKernel::Memory::KernelCheckedReleaseDirectMemory(physical, size) == 0,
+            "null texture output release failed");
+    std::printf("[gpu]     %-32s ok\n", name);
+  }
+
   void CheckScalarLeafCall() {
     constexpr const char* name = "ScalarLeafCall";
     constexpr uintptr_t base = 0x0000000204800000ull;
@@ -13007,6 +13107,8 @@ public:
       }
       ShaderRecompiler::IR::ApplyResourceSpecialization(
           null_program, null_specialization);
+      null_program.info.images.back().mip_mode = ShaderRecompiler::IR::ImageMipMode::Dynamic;
+      null_program.info.images.back().mip_count = 3;
       set_image_bindings(null_program);
       ShaderRecompiler::IR::CompiledShaderInfo null_info{};
       null_info.stage = null_program.stage;
@@ -13019,38 +13121,27 @@ public:
       Require(name, "null descriptor count",
               null_bindings.images.size() == 3,
               "null descriptor preparation lost an image binding");
-      const auto null_image_id = null_bindings.images[0].image_id;
-      const auto &null_image = texture_cache.GetImage(null_image_id);
-      Require(name, "one null image per format",
-              null_bindings.images[1].image_id == null_image_id &&
-                  null_bindings.images[2].image_id == null_image_id &&
-                  TextureCacheTestAccess::NullImageCount(texture_cache) == 1,
-              "null view dimension or usage created another image allocation");
-      Require(name, "null descriptors share final cache acquisition",
-              null_image.info.data.Empty() && !null_image.binding.is_bound &&
-                  !null_image.binding.is_target &&
-                  !null_image.binding.needs_rebind &&
-                  null_image.usage.storage &&
-                  null_image.IsGpuModified() &&
-                  !TextureCacheTestAccess::PendingDownload(texture_cache,
-                                                           null_image_id),
-              "the shared null image did not preserve texture/storage "
-              "acquisition without guest readback or RenderExecutor ownership");
       descriptor_pipelines.push_back(RenderExecutorTestAccess::CommitBindings(
           executor, scheduler.Current(), null_bindings));
-      Require(name, "null descriptor general layouts",
+      Require(name, "null descriptors have no cache image or native view",
               std::ranges::all_of(null_bindings.images,
                                   [](const auto &binding) {
                                     const auto info = MakeImageInfo(binding);
-                                    return binding.layout ==
+                                    return !binding.image_id &&
+                                           binding.image_view == nullptr &&
+                                           binding.mip_views.empty() &&
+                                           binding.layout ==
                                                vk::ImageLayout::eGeneral &&
-                                           info.imageView ==
-                                               binding.image_view &&
+                                           info.imageView == nullptr &&
                                            info.imageLayout == binding.layout;
-                                  }) &&
-                  null_image.backing.state.layout == vk::ImageLayout::eGeneral,
-              "shared sampled/storage null descriptors did not retain "
-              "the general layout through descriptor generation");
+                                  }),
+              "sampled/storage null descriptors acquired a backing image or lost their general layout");
+      for (u32 mip = 0; mip < 3; ++mip) {
+        const auto info = MakeImageInfo(null_bindings.images.back(), mip);
+        Require(name, "null storage mip descriptors",
+                info.imageView == nullptr && info.imageLayout == vk::ImageLayout::eGeneral,
+                "a null storage mip acquired a backing image");
+      }
 
       constexpr uint64_t target_mip_size = 0x10000;
       const auto make_target_desc = [&](uint64_t address, uint64_t size,
@@ -19244,10 +19335,14 @@ private:
     available_min_lod.pNext = &available_provoking_vertex;
     vk::PhysicalDeviceMaintenance8FeaturesKHR available_maintenance8{};
     available_maintenance8.pNext = &available_min_lod;
+    vk::PhysicalDeviceRobustness2FeaturesEXT available_robustness2{};
+    available_robustness2.pNext = &available_maintenance8;
     vk::PhysicalDeviceFeatures2 available_features2{};
     available_features2.sType = vk::StructureType::ePhysicalDeviceFeatures2;
-    available_features2.pNext = &available_maintenance8;
+    available_features2.pNext = &available_robustness2;
     m_physical_device.getFeatures2(&available_features2);
+    Require("VulkanHarness", "dispatch", available_robustness2.nullDescriptor == true,
+            "null descriptors are not supported");
     Require("VulkanHarness", "dispatch",
             available_features.shaderStorageImageWriteWithoutFormat == true,
             "shaderStorageImageWriteWithoutFormat is not supported");
@@ -19367,7 +19462,10 @@ private:
     vk::PhysicalDeviceMaintenance8FeaturesKHR maintenance8{};
     maintenance8.maintenance8 = true;
     maintenance8.pNext = &min_lod;
-    device_info.pNext = &maintenance8;
+    vk::PhysicalDeviceRobustness2FeaturesEXT robustness2{};
+    robustness2.nullDescriptor = true;
+    robustness2.pNext = &maintenance8;
+    device_info.pNext = &robustness2;
     vk::PhysicalDeviceFeatures device_features{};
     device_features.shaderStorageImageWriteWithoutFormat = true;
     device_features.shaderImageGatherExtended = true;
@@ -19384,6 +19482,7 @@ private:
         VK_KHR_FRAGMENT_SHADER_BARYCENTRIC_EXTENSION_NAME,
         VK_KHR_WORKGROUP_MEMORY_EXPLICIT_LAYOUT_EXTENSION_NAME,
         VK_EXT_SHADER_IMAGE_ATOMIC_INT64_EXTENSION_NAME,
+        VK_EXT_ROBUSTNESS_2_EXTENSION_NAME,
         VK_KHR_MAINTENANCE_8_EXTENSION_NAME,
         VK_EXT_IMAGE_VIEW_MIN_LOD_EXTENSION_NAME};
     if (m_rasterization_supported) {
@@ -46678,6 +46777,7 @@ int main(int argc, char **argv) {
   if (argc == 2 && std::strcmp(argv[1], "--indirect-image-only") == 0) {
     CheckImageSamplerSpecialization();
     VulkanHarness vulkan;
+    vulkan.CheckNullTextureDescriptors();
     CheckCountedRowImageSelector(vulkan);
     CheckPointerImageTable(vulkan);
     CheckNestedPointerImageTable(vulkan);
@@ -46872,6 +46972,7 @@ int main(int argc, char **argv) {
   vulkan.CheckGpuTilerCpuParity();
   vulkan.CheckNativeIndirectDispatch();
   CheckComputeLdsLimit(vulkan);
+  vulkan.CheckNullTextureDescriptors();
   vulkan.CheckBdaPageTableUploads();
   vulkan.CheckLargeSparseImageUpload();
   vulkan.CheckUnifiedTextureCacheFlow();