vk: Transient attachment support (#8021)

filament/backend/include/backend/DriverEnums.h

@@ -765,7 +765,8 @@ enum class TextureUsage : uint16_t {
     BLIT_SRC            = 0x0040,            //!< Texture can be used the source of a blit()
     BLIT_DST            = 0x0080,            //!< Texture can be used the destination of a blit()
     PROTECTED           = 0x0100,            //!< Texture can be used for protected content
-    DEFAULT             = UPLOADABLE | SAMPLEABLE   //!< Default texture usage
+    DEFAULT             = UPLOADABLE | SAMPLEABLE,   //!< Default texture usage
+    ALL_ATTACHMENTS     = COLOR_ATTACHMENT | DEPTH_ATTACHMENT | STENCIL_ATTACHMENT | SUBPASS_INPUT,   //!< Mask of all attachments
 };
 
 inline const char* stringify(TextureUsage usage) {

filament/backend/src/vulkan/VulkanContext.h

@@ -144,13 +144,18 @@ struct VulkanContext {
         return mPhysicalDeviceFeatures.shaderClipDistance == VK_TRUE;
     }
 
+    inline bool isLazilyAllocatedMemorySupported() const noexcept {
+        return mLazilyAllocatedMemorySupported;
+    }
+
 private:
     VkPhysicalDeviceMemoryProperties mMemoryProperties = {};
     VkPhysicalDeviceProperties mPhysicalDeviceProperties = {};
     VkPhysicalDeviceFeatures mPhysicalDeviceFeatures = {};
     bool mDebugMarkersSupported = false;
     bool mDebugUtilsSupported = false;
     bool mMultiviewEnabled = false;
+    bool mLazilyAllocatedMemorySupported = false;
 
     VkFormatList mDepthStencilFormats;
     VkFormatList mBlittableDepthStencilFormats;

filament/backend/src/vulkan/VulkanDriver.cpp

@@ -1283,12 +1283,14 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
 
     // Create the VkRenderPass or fetch it from cache.
     VulkanFboCache::RenderPassKey rpkey = {
-        .initialDepthLayout = currentDepthLayout,
         .depthFormat = depth.getFormat(),
         .clear = clearVal,
         .discardStart = discardStart,
         .discardEnd = discardEndVal,
+        .initialDepthLayout = currentDepthLayout,
         .samples = rt->getSamples(),
+        .needsResolveMask = 0,
+        .usesLazilyAllocatedMemory = 0,
         .subpassMask = uint8_t(params.subpassMask),
         .viewCount = renderTargetLayerCount,
     };
@@ -1297,8 +1299,16 @@ void VulkanDriver::beginRenderPass(Handle<HwRenderTarget> rth, const RenderPassP
         if (info.texture) {
             assert_invariant(info.layerCount == renderTargetLayerCount);
             rpkey.colorFormat[i] = info.getFormat();
-            if (rpkey.samples > 1 && info.texture->samples == 1) {
-                rpkey.needsResolveMask |= (1 << i);
+            if (rpkey.samples > 1) {
+                const VulkanTexture* sidecar = info.texture->getSidecar();
+                assert_invariant(sidecar);
+				assert_invariant(sidecar->samples > 1);
+                if (sidecar && sidecar->isTransientAttachment()) {
+                    rpkey.usesLazilyAllocatedMemory |= (1 << i);
+                }
+                if (info.texture->samples == 1) {
+                    rpkey.needsResolveMask |= (1 << i);
+                }
             }
         } else {
             rpkey.colorFormat[i] = VK_FORMAT_UNDEFINED;

filament/backend/src/vulkan/VulkanFboCache.cpp

@@ -41,6 +41,7 @@ bool VulkanFboCache::RenderPassEq::operator()(const RenderPassKey& k1,
     if (k1.discardEnd != k2.discardEnd) return false;
     if (k1.samples != k2.samples) return false;
     if (k1.needsResolveMask != k2.needsResolveMask) return false;
+    if (k1.usesLazilyAllocatedMemory != k2.usesLazilyAllocatedMemory) return false;
     if (k1.subpassMask != k2.subpassMask) return false;
     if (k1.viewCount != k2.viewCount) return false;
     return true;
@@ -254,7 +255,7 @@ VkRenderPass VulkanFboCache::getRenderPass(RenderPassKey config) noexcept {
             .format = config.colorFormat[i],
             .samples = (VkSampleCountFlagBits) config.samples,
             .loadOp = clear ? kClear : (discard ? kDontCare : kKeep),
-            .storeOp = kEnableStore,
+            .storeOp = (config.usesLazilyAllocatedMemory & (1 << i)) ? kDisableStore : kEnableStore,
             .stencilLoadOp = kDontCare,
             .stencilStoreOp = kDisableStore,
             .initialLayout = imgutil::getVkLayout(VulkanLayout::COLOR_ATTACHMENT),

filament/backend/src/vulkan/VulkanFboCache.h

@@ -42,18 +42,19 @@ class VulkanFboCache {
     // RenderPassKey is a small POD representing the immutable state that is used to construct
     // a VkRenderPass. It is hashed and used as a lookup key.
     struct alignas(8) RenderPassKey {
-        VulkanLayout initialDepthLayout;
-        uint8_t padding[3] = {};
-
         VkFormat colorFormat[MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT]; // 32 bytes
         VkFormat depthFormat; // 4 bytes
         TargetBufferFlags clear; // 4 bytes
         TargetBufferFlags discardStart; // 4 bytes
         TargetBufferFlags discardEnd; // 4 bytes
+
+        VulkanLayout initialDepthLayout; // 1 byte
         uint8_t samples; // 1 byte
         uint8_t needsResolveMask; // 1 byte
+        uint8_t usesLazilyAllocatedMemory; // 1 byte
         uint8_t subpassMask; // 1 byte
         uint8_t viewCount; // 1 byte
+		uint8_t padding[2];
     };
     struct RenderPassVal {
         VkRenderPass handle;

filament/backend/src/vulkan/VulkanHandles.cpp

@@ -282,11 +282,16 @@ VulkanRenderTarget::VulkanRenderTarget(VkDevice device, VkPhysicalDevice physica
         if (texture && texture->samples == 1) {
             auto msTexture = texture->getSidecar();
             if (UTILS_UNLIKELY(!msTexture)) {
+                // Clear all usage flags that are not related to attachments, so that we can
+                // use the transient usage flag.
+                const TextureUsage usage = texture->usage & TextureUsage::ALL_ATTACHMENTS;
+                assert_invariant(static_cast<uint16_t>(usage) != 0U);
+
                 // TODO: This should be allocated with the ResourceAllocator.
                 msTexture = new VulkanTexture(device, physicalDevice, context, allocator, commands,
                         handleAllocator,
                         texture->target, ((VulkanTexture const*) texture)->levels, texture->format,
-                        samples, texture->width, texture->height, texture->depth, texture->usage,
+                        samples, texture->width, texture->height, texture->depth, usage,
                         stagePool, true /* heap allocated */);
                 texture->setSidecar(msTexture);
             }

filament/backend/src/vulkan/VulkanTexture.cpp

@@ -128,7 +128,8 @@ VulkanTextureState::VulkanTextureState(
           mStagePool(stagePool),
           mDevice(device),
           mAllocator(allocator),
-          mCommands(commands) {
+          mCommands(commands),
+          mIsTransientAttachment(false) {
 }
 
 VulkanTextureState* VulkanTexture::getSharedState() {
@@ -209,6 +210,19 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
         imageInfo.usage |= VK_IMAGE_USAGE_TRANSFER_DST_BIT;
     }
 
+    // Determine if we can use the transient usage flag combined with lazily allocated memory.
+    const bool useTransientAttachment =
+        // Lazily allocated memory is available.
+        context.isLazilyAllocatedMemorySupported() &&
+        // Usage consists of attachment flags only.
+        none(tusage & ~TextureUsage::ALL_ATTACHMENTS) &&
+        // Usage contains at least one attachment flag.
+        any(tusage & TextureUsage::ALL_ATTACHMENTS);
+    state->mIsTransientAttachment = useTransientAttachment;
+
+    const VkImageUsageFlags transientFlag =
+       useTransientAttachment ? VK_IMAGE_USAGE_TRANSIENT_ATTACHMENT_BIT : 0U;
+
     if (any(usage & TextureUsage::SAMPLEABLE)) {
 
 #if FVK_ENABLED(FVK_DEBUG_TEXTURE)
@@ -224,19 +238,19 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
         imageInfo.usage |= VK_IMAGE_USAGE_SAMPLED_BIT;
     }
     if (any(usage & TextureUsage::COLOR_ATTACHMENT)) {
-        imageInfo.usage |= VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
+        imageInfo.usage |= VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | transientFlag;
         if (any(usage & TextureUsage::SUBPASS_INPUT)) {
             imageInfo.usage |= VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT;
         }
     }
     if (any(usage & TextureUsage::STENCIL_ATTACHMENT)) {
-        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT;
+        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT | transientFlag;
     }
     if (any(usage & TextureUsage::UPLOADABLE)) {
         imageInfo.usage |= VK_IMAGE_USAGE_TRANSFER_DST_BIT;
     }
     if (any(usage & TextureUsage::DEPTH_ATTACHMENT)) {
-        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT;
+        imageInfo.usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT | transientFlag;
 
         // Depth resolves uses a custom shader and therefore needs to be sampleable.
         if (samples > 1) {
@@ -285,8 +299,11 @@ VulkanTexture::VulkanTexture(VkDevice device, VkPhysicalDevice physicalDevice,
     VkMemoryRequirements memReqs = {};
     vkGetImageMemoryRequirements(state->mDevice, state->mTextureImage, &memReqs);
 
+    const VkFlags requiredMemoryFlags =
+        VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT |
+        (useTransientAttachment ? VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT : 0U);
     uint32_t memoryTypeIndex
-            = context.selectMemoryType(memReqs.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+            = context.selectMemoryType(memReqs.memoryTypeBits, requiredMemoryFlags);
 
     FILAMENT_CHECK_POSTCONDITION(memoryTypeIndex < VK_MAX_MEMORY_TYPES)
             << "VulkanTexture: unable to find a memory type that meets requirements.";

filament/backend/src/vulkan/VulkanTexture.h

@@ -79,6 +79,7 @@ struct VulkanTextureState : public VulkanResource {
     VmaAllocator mAllocator;
     VulkanCommands* mCommands;
     std::shared_ptr<VulkanCmdFence> mTransitionFence;
+    bool mIsTransientAttachment;
 };
 
 
@@ -170,6 +171,11 @@ struct VulkanTexture : public HwTexture, VulkanResource {
         return state->mSidecarMSAA.get();
     }
 
+    bool isTransientAttachment() const {
+        VulkanTextureState const* state = getSharedState();
+        return state->mIsTransientAttachment;
+    }
+
     bool transitionLayout(VulkanCommandBuffer* commands, const VkImageSubresourceRange& range,
             VulkanLayout newLayout);
 

filament/backend/src/vulkan/platform/VulkanPlatform.cpp

@@ -740,6 +740,20 @@ Driver* VulkanPlatform::createDriver(void* sharedContext,
     context.mDebugMarkersSupported = setContains(deviceExts, VK_EXT_DEBUG_MARKER_EXTENSION_NAME);
     context.mMultiviewEnabled = setContains(deviceExts, VK_KHR_MULTIVIEW_EXTENSION_NAME);
 
+    // Check the availability of lazily allocated memory
+    {
+        context.mLazilyAllocatedMemorySupported = false;
+        const uint32_t typeCount = context.mMemoryProperties.memoryTypeCount;
+        for(uint32_t i = 0; i < typeCount; ++i) {
+            const VkMemoryType type = context.mMemoryProperties.memoryTypes[i];
+            if (type.propertyFlags & VK_MEMORY_PROPERTY_LAZILY_ALLOCATED_BIT) {
+                context.mLazilyAllocatedMemorySupported = true;
+                assert_invariant(type.propertyFlags & VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+                break;
+            }
+        }
+    }
+
 #ifdef NDEBUG
     // If we are in release build, we should not have turned on debug extensions
     FILAMENT_CHECK_POSTCONDITION(!context.mDebugUtilsSupported && !context.mDebugMarkersSupported)