[Docs] (docs/Performance): add a skill for reading Mali GPU counters

- A whole-window clear with a window pass open ends that pass and folds
  into the next one, instead of running a load-clear-store pass of its own
- A present drops the depth/stencil half of a pending window clear

MobileGL/MG_Backend/DirectVulkan/Renderer/VkTextureManager.h

@@ -132,6 +132,9 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         private:
             VkTextureManager& m_manager;
         };
+        // True inside a PendingClearHold: the image being resolved is an attachment of the pass
+        // being prepared, which takes pending clears as its load op.
+        Bool PendingClearsHeld() const { return m_pendingClearHold != 0; }
         // A whole-subresource clear that was recorded but has not run yet (VulkanRenderer::DeferWireClear).
         struct WirePendingClear {
             Uint32 level = 0, layer = 0, layers = 1;

MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRenderer.h

@@ -620,7 +620,30 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             Uint32 level = 0, layer = 0, layers = 1;
         };
         Vector<WireFoldClear> m_wireFoldClears;
+        // Attachments of the pass being prepared whose content is undefined: a default-framebuffer
+        // image first used since its present. Their load op becomes DONT_CARE (WireClearVariant).
+        Vector<Uint32> m_wireDiscardLoads;
         static Bool WireImageCanDeferClear(const WireImage& image);
+        // A whole-image clear of the default framebuffer, held for the next pass that draws into
+        // the window (its load op) the way WirePendingClear holds a texture's. Any other use of the
+        // window images, and the present, run it first (MaterializeDefaultWirePendingClear).
+        struct DefaultWirePendingClear {
+            VkSwapchainKHR swapchain = VK_NULL_HANDLE;
+            Uint32 swapchainImageIndex = 0;
+            Bool color = false;
+            VkImageAspectFlags depthStencil = 0;
+            ClearAttachmentPayload colorPayload{};
+            ClearAttachmentPayload depthStencilPayload{};
+            Bool Pending() const { return color || depthStencil != 0; }
+        };
+        DefaultWirePendingClear m_defaultWirePendingClear;
+        GLbitfield DeferDefaultWireClear(const MG_Pipe::MGPFramebufferState& fbo, const ClearAttachmentPayload& payload,
+                                         GLint drawbuffer);
+        void MaterializeDefaultWirePendingClear();
+        void FoldDefaultWirePendingClear(RenderPassEntry& begun, Uint64& variantKey, VkClearValue* merged);
+        // Records a clear of `area` of one wire image in a single-attachment pass of its own.
+        void RecordWireImageClear(WireImage& image, VkImageAspectFlags aspect, const ClearAttachmentPayload& payload,
+                                  const VkRect2D& area, Bool textureSurface);
         static void NoteWirePendingClear(const WireImage& image, VkImageAspectFlags aspects, const VkClearValue& value);
         VkRenderPass WireClearVariant(RenderPassEntry& begun, Uint64 variantKey);
         Bool BeginWireDrawPassFolding(FrameContext::FrameData& frame, RenderPassEntry& begun, Uint64 variantKey,

MobileGL/MG_Backend/DirectVulkan/Renderer/VulkanRendererPresent.cpp

@@ -16,6 +16,15 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         // Present has its own submit path. Tag its last wire pass before that
         // submission, rather than retaining it until a draw in the next frame.
         RetireWireDrawPass();
+        // A window color clear no pass drew after still has to reach the presented image. Its
+        // depth/stencil half is dropped: a swap leaves those undefined (see the content flags
+        // reset below). A frame that cannot be presented drops the whole clear.
+        if (m_swapchainObject.GetHandle() == VK_NULL_HANDLE || m_presentSuspended) {
+            m_defaultWirePendingClear = {};
+        } else {
+            m_defaultWirePendingClear.depthStencil = 0;
+            MaterializeDefaultWirePendingClear();
+        }
 #endif
         if (m_swapchainObject.GetHandle() == VK_NULL_HANDLE || m_presentSuspended) {
             // No usable swapchain: the window was zero-area at initialization, or

MobileGL/MG_Backend/DirectVulkan/Renderer/WireDraw.cpp

@@ -9,6 +9,14 @@
 #include "VulkanRendererInternal.h"
 
 namespace MobileGL::MG_Backend::DirectVulkan {
+    namespace {
+        // A wire pass variant key holds two clear bits per attachment from bit 0 and, from this
+        // bit on, one bit per attachment whose content is undefined (WireClearVariant).
+        constexpr Uint32 kWireDiscardBit = 32;
+        static_assert(2 * (MG_Pipe::kMGPipeMaxColorAttachments + 1) <= kWireDiscardBit,
+                      "the clear bits of a wire pass variant key overlap its discard bits");
+    } // namespace
+
     // GL_EXT_fragment_shading_rate's pipeline rate and combiner ops for the draw about to be
     // recorded. The packed rate is log2(width) << 2 | log2(height), which is exactly the extent
     // VK_KHR_fragment_shading_rate takes, and the combiner op indices follow
@@ -445,6 +453,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                                              WireDrawScratch& scratch, Bool passContinues, Bool& continuing) {
         continuing = true;
         m_wireFoldClears.clear();
+        m_wireDiscardLoads.clear();
         if (passContinues) {
             auto& store = MG_Record::ServerStagedTexture();
             if (!m_wirePassMarksValid || m_wirePassMarksClearGeneration != store.GpuDirtyClearGeneration()) {
@@ -536,6 +545,13 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                 if (!image.isDefault && surface.Kind == MG_Pipe::kMGPipeSurfaceKindTexture)
                     scratch.gpuWriteMarks.push_back({image.storage, image.level, image.layer, image.layers});
                 if (image.isDefault) {
+                    // A present leaves the default framebuffer undefined (VulkanRenderer::Present):
+                    // the first pass after it has nothing to load.
+                    const Bool defined =
+                        aspect == VK_IMAGE_ASPECT_COLOR_BIT
+                            ? m_swapchainObject.IsImageContentDefined(image.swapchainImageIndex)
+                            : m_swapchainObject.IsDepthStencilContentDefined(image.swapchainImageIndex);
+                    if (!defined) m_wireDiscardLoads.push_back(static_cast<Uint32>(attachments.size() - 1));
                     if (aspect == VK_IMAGE_ASPECT_COLOR_BIT)
                         m_swapchainObject.SetImageContentDefined(image.swapchainImageIndex, true);
                     else
@@ -1361,9 +1377,18 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             if (entry.first == variantKey) return entry.second;
         const Uint32 attachmentCount = static_cast<Uint32>(begun.wireAttachments.size());
         auto descriptions = begun.wireAttachments;
+        // Bits 2a and 2a+1 clear attachment a (color or depth, and stencil); bit kWireDiscardBit + a
+        // marks its content undefined, so whatever is not cleared is not loaded either.
         for (Uint32 a = 0; a < attachmentCount; ++a) {
-            if (variantKey >> (2 * a) & 1) descriptions[a].loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
-            if (variantKey >> (2 * a + 1) & 1) descriptions[a].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+            const Bool discard = variantKey >> (kWireDiscardBit + a) & 1;
+            if (variantKey >> (2 * a) & 1)
+                descriptions[a].loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+            else if (discard)
+                descriptions[a].loadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+            if (variantKey >> (2 * a + 1) & 1)
+                descriptions[a].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+            else if (discard)
+                descriptions[a].stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
         }
         VkSubpassDescription subpass{};
         subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
@@ -1382,6 +1407,139 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         return variant;
     }
 
+    // The default framebuffer's half of the deferred clears: a whole-window glClear waits for the
+    // next pass that draws into the window, which loads it with LOAD_OP_CLEAR
+    // (BeginWireDrawPassFolding) instead of storing a cleared window and loading it back. A pass
+    // open on the window ends first, since the in-pass clear does not take the window
+    // (MagmaInPassClearDefault); a present drops the depth/stencil half (Present). Returns the
+    // buffers it did not take.
+    GLbitfield VulkanRenderer::DeferDefaultWireClear(const MG_Pipe::MGPFramebufferState& fbo,
+                                                     const ClearAttachmentPayload& payload, GLint drawbuffer) {
+        GLbitfield remaining = payload.mask & (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+        if (!remaining || !fbo.IsDefault || drawbuffer >= 0 || m_wirePreparationDepth != 0) return remaining;
+        if (GLScissorTestClips()) return remaining;
+        GLbitfield handled = 0;
+        Bool color = false;
+        VkImageAspectFlags depthStencil = 0;
+        if (remaining & GL_COLOR_BUFFER_BIT) {
+            const Int32 slot = fbo.DrawBuffers[0];
+            const auto mask = MG_Pipe::gPipeInputs->GetColorMaskIndexed(0);
+            const Bool none = slot < 0 || (!mask.r() && !mask.g() && !mask.b() && !mask.a());
+            if (none)
+                handled |= GL_COLOR_BUFFER_BIT;
+            else if (mask.r() && mask.g() && mask.b() && mask.a() &&
+                     payload.colorEncoding == ClearColorEncoding::Float) {
+                handled |= GL_COLOR_BUFFER_BIT;
+                color = true;
+            }
+        }
+        // A window without a depth/stencil buffer clears nothing there.
+        const VkFormat depthStencilFormat = m_swapchainObject.GetDepthStencilFormat();
+        const Bool hasDepth = depthStencilFormat != VK_FORMAT_UNDEFINED;
+        const Bool packed = vkuFormatIsDepthAndStencil(depthStencilFormat);
+        if (remaining & GL_DEPTH_BUFFER_BIT) {
+            handled |= GL_DEPTH_BUFFER_BIT;
+            if (hasDepth && MG_Pipe::gPipeInputs->GetDepthMask()) depthStencil |= VK_IMAGE_ASPECT_DEPTH_BIT;
+        }
+        if (remaining & GL_STENCIL_BUFFER_BIT) {
+            const Uint32 mask = MG_Pipe::gPipeInputs->GetStencilState(StencilFace::Front).WriteMask & 255u;
+            if (mask == 0 || !packed)
+                handled |= GL_STENCIL_BUFFER_BIT;
+            else if (mask == 255u) {
+                handled |= GL_STENCIL_BUFFER_BIT;
+                depthStencil |= VK_IMAGE_ASPECT_STENCIL_BIT;
+            }
+        }
+        if (!color && depthStencil == 0) return remaining & ~handled;
+        if (VkRenderPassManager::GetActiveRenderPass() != nullptr && m_wireDrawPass && m_wireDrawPassKey.isDefault)
+            RetireWireDrawPass();
+        // The index the next drawing pass on the window will address (WireDraw.cpp's pass key).
+        const Uint32 index = DefaultFramebufferWriteIndex(true);
+        auto& pending = m_defaultWirePendingClear;
+        if (pending.Pending() &&
+            (pending.swapchain != m_swapchainObject.GetHandle() || pending.swapchainImageIndex != index))
+            MaterializeDefaultWirePendingClear();
+        pending.swapchain = m_swapchainObject.GetHandle();
+        pending.swapchainImageIndex = index;
+        if (color) {
+            pending.color = true;
+            pending.colorPayload = payload;
+            m_swapchainObject.SetImageContentDefined(index, true);
+        }
+        if (depthStencil & VK_IMAGE_ASPECT_DEPTH_BIT) pending.depthStencilPayload.depth = payload.depth;
+        if (depthStencil & VK_IMAGE_ASPECT_STENCIL_BIT) pending.depthStencilPayload.stencil = payload.stencil;
+        if (depthStencil) {
+            pending.depthStencil |= depthStencil;
+            m_swapchainObject.SetDepthStencilContentDefined(index, true);
+        }
+        return remaining & ~handled;
+    }
+
+    void VulkanRenderer::MaterializeDefaultWirePendingClear() {
+        if (!m_defaultWirePendingClear.Pending()) return;
+        const DefaultWirePendingClear pending = m_defaultWirePendingClear;
+        m_defaultWirePendingClear = {};
+        // A recreated swapchain took the images the clear was for.
+        if (pending.swapchain != m_swapchainObject.GetHandle() ||
+            pending.swapchainImageIndex >= m_swapchainObject.GetImageCount())
+            return;
+        const VkExtent2D extent = m_swapchainObject.GetExtent();
+        const VkRect2D area{{0, 0}, extent};
+        WireImage image{};
+        image.isDefault = true;
+        image.extent = extent;
+        image.swapchainImageIndex = pending.swapchainImageIndex;
+        if (pending.color) {
+            image.aspect = VK_IMAGE_ASPECT_COLOR_BIT;
+            image.image = m_swapchainObject.GetImage(pending.swapchainImageIndex);
+            image.format = m_swapchainObject.GetSurfaceFormat().format;
+            image.layout = m_swapchainObject.GetImageLayout(pending.swapchainImageIndex);
+            RecordWireImageClear(image, VK_IMAGE_ASPECT_COLOR_BIT, pending.colorPayload, area, false);
+        }
+        if (pending.depthStencil && m_swapchainObject.GetDepthStencilImage(pending.swapchainImageIndex)) {
+            image.aspect = pending.depthStencil;
+            image.image = m_swapchainObject.GetDepthStencilImage(pending.swapchainImageIndex);
+            image.format = m_swapchainObject.GetDepthStencilFormat();
+            image.layout = m_swapchainObject.GetDepthStencilImageLayout(pending.swapchainImageIndex);
+            RecordWireImageClear(image, pending.depthStencil, pending.depthStencilPayload, area, false);
+        }
+    }
+
+    // A pending window clear (DeferDefaultWireClear) becomes the load op of the window pass that
+    // begins: its attachments are matched by image, since a continued pass key is not walked again.
+    // A clear the caller already put in `variantKey` is newer and wins.
+    void VulkanRenderer::FoldDefaultWirePendingClear(RenderPassEntry& begun, Uint64& variantKey, VkClearValue* merged) {
+        auto& pending = m_defaultWirePendingClear;
+        if (!pending.Pending() || !m_wireDrawPassKey.isDefault || m_wireDrawPassKey.swapchain != pending.swapchain ||
+            m_wireDrawPassKey.swapchainImageIndex != pending.swapchainImageIndex)
+            return;
+        const Uint32 attachmentCount =
+            static_cast<Uint32>(std::min<SizeT>(begun.wireAttachments.size(), m_wireDrawPassKey.attachments.size()));
+        const VkImage colorImage = m_swapchainObject.GetImage(pending.swapchainImageIndex);
+        const VkImage depthStencilImage = m_swapchainObject.GetDepthStencilImage(pending.swapchainImageIndex);
+        for (Uint32 a = 0; a < attachmentCount && a < MG_Pipe::kMGPipeMaxColorAttachments + 1; ++a) {
+            const auto& attachment = m_wireDrawPassKey.attachments[a];
+            if (pending.color && attachment.image == colorImage) {
+                if (!(variantKey >> (2 * a) & 1)) {
+                    variantKey |= 1ull << (2 * a);
+                    merged[a].color = MakeVkClearColorValue(pending.colorPayload, false);
+                }
+                pending.color = false;
+            } else if (pending.depthStencil && attachment.image == depthStencilImage) {
+                if ((pending.depthStencil & VK_IMAGE_ASPECT_DEPTH_BIT) && !(variantKey >> (2 * a) & 1)) {
+                    variantKey |= 1ull << (2 * a);
+                    merged[a].depthStencil.depth = pending.depthStencilPayload.depth;
+                }
+                if ((pending.depthStencil & VK_IMAGE_ASPECT_STENCIL_BIT) && !(variantKey >> (2 * a + 1) & 1)) {
+                    variantKey |= 1ull << (2 * a + 1);
+                    merged[a].depthStencil.stencil = pending.depthStencilPayload.stencil;
+                }
+                pending.depthStencil = 0;
+            }
+        }
+        // An aspect the pass does not attach stays pending: none of its draws write it.
+    }
+
     // P15: EVERY DRAW PASS BEGINS HERE. The pending clears of its attachments
     // (m_wireFoldClears, gathered by PrepareWireDrawPass) become their load op and leave the
     // images; a clear the caller already put in `variantKey` (its own glClear, newer than any
@@ -1426,6 +1584,10 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             }
         }
         m_wireFoldClears.clear();
+        FoldDefaultWirePendingClear(begun, variantKey, merged);
+        for (const Uint32 a : m_wireDiscardLoads)
+            if (a < attachmentCount) variantKey |= 1ull << (kWireDiscardBit + a);
+        m_wireDiscardLoads.clear();
         if (variantKey == 0) return VkRenderPassManager::BeginRenderPass(frame.commandBuffer, begun);
         return VkRenderPassManager::BeginRenderPass(frame.commandBuffer, begun, WireClearVariant(begun, variantKey),
                                                     merged, attachmentCount);

MobileGL/MG_Backend/DirectVulkan/Renderer/WireFramebuffer.cpp

@@ -658,6 +658,10 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         WireImage out{};
         out.aspect = aspect;
         if (fbo.IsDefault) {
+            // Only an attachment of the pass being prepared takes a pending window clear as its
+            // load op; every other use runs it first.
+            if (m_defaultWirePendingClear.Pending() && !m_textureManager->PendingClearsHeld())
+                MaterializeDefaultWirePendingClear();
             out.isDefault = true;
             out.extent = m_swapchainObject.GetExtent();
             out.swapchainImageIndex =
@@ -1109,6 +1113,87 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         return remaining & ~handled;
     }
 
+    void VulkanRenderer::RecordWireImageClear(WireImage& image, VkImageAspectFlags aspect,
+                                              const ClearAttachmentPayload& payload, const VkRect2D& area,
+                                              Bool textureSurface) {
+        const Bool color = aspect == VK_IMAGE_ASPECT_COLOR_BIT;
+        const auto layout =
+            color ? VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL : VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
+        TransitionWireImage(image, layout);
+        VkImageViewCreateInfo viewInfo{VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO};
+        viewInfo.image = image.image;
+        viewInfo.viewType = image.viewType;
+        viewInfo.format = image.format;
+        viewInfo.subresourceRange = {
+            color ? VK_IMAGE_ASPECT_COLOR_BIT
+                  : (image.format == VK_FORMAT_D24_UNORM_S8_UINT || image.format == VK_FORMAT_D32_SFLOAT_S8_UINT
+                         ? VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT
+                         : image.aspect),
+            image.level, 1, image.layer, image.layers};
+        VkImageView view = VK_NULL_HANDLE;
+        VK_VERIFY(vkCreateImageView(m_device, &viewInfo, nullptr, &view));
+        VkAttachmentDescription attachment{};
+        attachment.format = image.format;
+        attachment.samples = image.samples;
+        attachment.loadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
+        attachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+        attachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
+        attachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_STORE;
+        attachment.initialLayout = layout;
+        attachment.finalLayout = layout;
+        VkAttachmentReference ref{0, layout};
+        VkSubpassDescription subpass{};
+        subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+        subpass.colorAttachmentCount = color ? 1 : 0;
+        subpass.pColorAttachments = color ? &ref : nullptr;
+        subpass.pDepthStencilAttachment = color ? nullptr : &ref;
+        VkRenderPassCreateInfo passInfo{VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO};
+        passInfo.attachmentCount = 1;
+        passInfo.pAttachments = &attachment;
+        passInfo.subpassCount = 1;
+        passInfo.pSubpasses = &subpass;
+        VkRenderPass pass = VK_NULL_HANDLE;
+        VK_VERIFY(vkCreateRenderPass(m_device, &passInfo, nullptr, &pass));
+        VkFramebufferCreateInfo fbInfo{VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO};
+        fbInfo.renderPass = pass;
+        fbInfo.attachmentCount = 1;
+        fbInfo.pAttachments = &view;
+        fbInfo.width = image.extent.width;
+        fbInfo.height = image.extent.height;
+        fbInfo.layers = image.layers;
+        VkFramebuffer fb = VK_NULL_HANDLE;
+        VK_VERIFY(vkCreateFramebuffer(m_device, &fbInfo, nullptr, &fb));
+        VkRenderPassBeginInfo begin{VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO};
+        begin.renderPass = pass;
+        begin.framebuffer = fb;
+        begin.renderArea = area;
+        auto clearPayload = payload;
+        if (color) PreCompensateSrgbClearColor(clearPayload, image.format);
+        VkClearAttachment clear{};
+        clear.aspectMask = aspect;
+        clear.clearValue.color = MakeVkClearColorValue(clearPayload, false);
+        if (!color) clear.clearValue.depthStencil = {payload.depth, payload.stencil};
+        VkClearRect rect{area, 0, image.layers};
+        auto& frame = m_frameContext.GetCurrent();
+        EndActiveRenderPassOn(frame.commandBuffer);
+        vkCmdBeginRenderPass(frame.commandBuffer, &begin, VK_SUBPASS_CONTENTS_INLINE);
+        vkCmdClearAttachments(frame.commandBuffer, 1, &clear, 1, &rect);
+        vkCmdEndRenderPass(frame.commandBuffer);
+        WireRetiredObjects retired{};
+        retired.framebuffers.push_back(fb);
+        retired.renderPasses.push_back(pass);
+        retired.imageViews.push_back(view);
+        RetireWireObjects(Move(retired));
+        if (!image.isDefault && textureSurface)
+            m_textureManager->MarkWireTextureGpuWritten(image.storage, image.level, image.layer, image.layers);
+        if (image.isDefault) {
+            if (color)
+                m_swapchainObject.SetImageContentDefined(image.swapchainImageIndex, true);
+            else
+                m_swapchainObject.SetDepthStencilContentDefined(image.swapchainImageIndex, true);
+        }
+    }
+
     void VulkanRenderer::ClearWireFramebuffer(const MG_Pipe::MGPFramebufferState& fbo,
                                               const ClearAttachmentPayload& clearRequest, GLint drawbuffer) {
         if (MG_Pipe::gPipeInputs->IsCapabilityEnabled(CapabilityInput::RasterizerDiscard)) return;
@@ -1126,6 +1211,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             payload.mask = ClearWireFramebufferInPass(fbo, payload, drawbuffer);
         if (payload.mask) payload.mask = ClearWireAttachmentsOfOpenPass(fbo, payload, drawbuffer);
         if (payload.mask) payload.mask = DeferWireClear(fbo, payload, drawbuffer);
+        if (payload.mask) payload.mask = DeferDefaultWireClear(fbo, payload, drawbuffer);
         if (payload.mask) payload.mask = ClearWireFramebufferInPass(fbo, payload, drawbuffer);
         if (!payload.mask) return;
         RetireWireDrawPass();
@@ -1177,82 +1263,7 @@ namespace MobileGL::MG_Backend::DirectVulkan {
                                                        m_swapchainObject.GetPreTransform(), &area.offset, &area.extent))
                     MagmaWireFatal("clear-surface-transform");
             }
-            const Bool color = aspect == VK_IMAGE_ASPECT_COLOR_BIT;
-            const auto layout =
-                color ? VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL : VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL;
-            TransitionWireImage(image, layout);
-            VkImageViewCreateInfo viewInfo{VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO};
-            viewInfo.image = image.image;
-            viewInfo.viewType = image.viewType;
-            viewInfo.format = image.format;
-            viewInfo.subresourceRange = {
-                color ? VK_IMAGE_ASPECT_COLOR_BIT
-                      : (image.format == VK_FORMAT_D24_UNORM_S8_UINT || image.format == VK_FORMAT_D32_SFLOAT_S8_UINT
-                             ? VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT
-                             : image.aspect),
-                image.level, 1, image.layer, image.layers};
-            VkImageView view = VK_NULL_HANDLE;
-            VK_VERIFY(vkCreateImageView(m_device, &viewInfo, nullptr, &view));
-            VkAttachmentDescription attachment{};
-            attachment.format = image.format;
-            attachment.samples = image.samples;
-            attachment.loadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
-            attachment.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
-            attachment.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_LOAD;
-            attachment.stencilStoreOp = VK_ATTACHMENT_STORE_OP_STORE;
-            attachment.initialLayout = layout;
-            attachment.finalLayout = layout;
-            VkAttachmentReference ref{0, layout};
-            VkSubpassDescription subpass{};
-            subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
-            subpass.colorAttachmentCount = color ? 1 : 0;
-            subpass.pColorAttachments = color ? &ref : nullptr;
-            subpass.pDepthStencilAttachment = color ? nullptr : &ref;
-            VkRenderPassCreateInfo passInfo{VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO};
-            passInfo.attachmentCount = 1;
-            passInfo.pAttachments = &attachment;
-            passInfo.subpassCount = 1;
-            passInfo.pSubpasses = &subpass;
-            VkRenderPass pass = VK_NULL_HANDLE;
-            VK_VERIFY(vkCreateRenderPass(m_device, &passInfo, nullptr, &pass));
-            VkFramebufferCreateInfo fbInfo{VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO};
-            fbInfo.renderPass = pass;
-            fbInfo.attachmentCount = 1;
-            fbInfo.pAttachments = &view;
-            fbInfo.width = image.extent.width;
-            fbInfo.height = image.extent.height;
-            fbInfo.layers = image.layers;
-            VkFramebuffer fb = VK_NULL_HANDLE;
-            VK_VERIFY(vkCreateFramebuffer(m_device, &fbInfo, nullptr, &fb));
-            VkRenderPassBeginInfo begin{VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO};
-            begin.renderPass = pass;
-            begin.framebuffer = fb;
-            begin.renderArea = area;
-            auto clearPayload = payload;
-            if (color) PreCompensateSrgbClearColor(clearPayload, image.format);
-            VkClearAttachment clear{};
-            clear.aspectMask = aspect;
-            clear.clearValue.color = MakeVkClearColorValue(clearPayload, false);
-            if (!color) clear.clearValue.depthStencil = {payload.depth, payload.stencil};
-            VkClearRect rect{area, 0, image.layers};
-            auto& frame = m_frameContext.GetCurrent();
-            EndActiveRenderPassOn(frame.commandBuffer);
-            vkCmdBeginRenderPass(frame.commandBuffer, &begin, VK_SUBPASS_CONTENTS_INLINE);
-            vkCmdClearAttachments(frame.commandBuffer, 1, &clear, 1, &rect);
-            vkCmdEndRenderPass(frame.commandBuffer);
-            WireRetiredObjects retired{};
-            retired.framebuffers.push_back(fb);
-            retired.renderPasses.push_back(pass);
-            retired.imageViews.push_back(view);
-            RetireWireObjects(Move(retired));
-            if (!image.isDefault && surface.Kind == MG_Pipe::kMGPipeSurfaceKindTexture)
-                m_textureManager->MarkWireTextureGpuWritten(image.storage, image.level, image.layer, image.layers);
-            if (image.isDefault) {
-                if (color)
-                    m_swapchainObject.SetImageContentDefined(image.swapchainImageIndex, true);
-                else
-                    m_swapchainObject.SetDepthStencilContentDefined(image.swapchainImageIndex, true);
-            }
+            RecordWireImageClear(image, aspect, payload, area, surface.Kind == MG_Pipe::kMGPipeSurfaceKindTexture);
         };
         if (payload.mask & GL_COLOR_BUFFER_BIT) {
             for (Uint32 i = 0; i < MG_Pipe::kMGPipeMaxColorAttachments; ++i) {

MobileGL/MG_IntegrationTest/Scenarios/InPassClearScenario.cpp

@@ -357,4 +357,35 @@ void main() { o0 = texture(uPalette, vec2(0.5, 0.5)); }
         glDeleteProgram(paletteProgram);
     }
 
+    // A depth clear of the DEFAULT framebuffer while a pass is open on it (a game clearing depth
+    // before its hand or GUI): the in-pass clear does not take the window, so the clear ends the
+    // pass and becomes the load op of the next one, which the farther draw must see.
+    TEST_F(InPassClearScenario, ADefaultFramebufferDepthClearBetweenTestedDrawsDecidesTheSecondDraw) {
+        if (!Ready()) return;
+        HeadlessGL& gl = Gl();
+        const int width = gl.Width(), height = gl.Height();
+        Build();
+        for (int frame = 0; frame < 2; ++frame) {
+            BindDefaultFramebuffer();
+            glViewport(0, 0, width, height);
+            glDisable(GL_SCISSOR_TEST);
+            glDisable(GL_BLEND);
+            glDepthMask(GL_TRUE);
+            glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+            glClearDepth(1.0);
+            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+            glEnable(GL_DEPTH_TEST);
+            glDepthFunc(GL_LESS);
+            Quad(1.0f, 0.0f, 0.0f, 1.0f, -0.5f);
+            glClear(GL_DEPTH_BUFFER_BIT);
+            Quad(0.0f, 1.0f, 0.0f, 1.0f, 0.0f);
+            glDisable(GL_DEPTH_TEST);
+            EXPECT_EQ(FirstGLError(), 0u);
+            const Image image = ReadPixels(width, height);
+            EXPECT_TRUE(Near(image.At(width / 2, height / 2), 0, 255, 0, 255))
+                << "frame " << frame << ": the depth clear between the draws let the farther draw pass";
+            gl.EndFrame();
+        }
+    }
+
 } // namespace MGITest

docs/Performance/mali-gpu-counters/SKILL.md

@@ -0,0 +1,158 @@
+---
+name: mali-gpu-counters
+description: Capture and compare Mali GPU hardware counters (fragment/vertex cycles, tiles, ZS, bandwidth, tile write elimination) on a rooted Android phone through perfetto and the vendor's libgpudataproducer, to find where one renderer spends more GPU time than another. Use when a GPU-bound workload is slower on Magma (DirectVulkan) than on the device's GLES driver, or slower after a change, and you need to know which part of the GPU pipeline the gap is in.
+---
+
+# Mali GPU performance counters
+
+Use this to answer "where does Magma spend the GPU time that the system GLES driver (or the previous build) doesn't?" on a Mali phone. Two captures, each normalized per frame, show which pipeline stage is responsible: vertex/tiling, fragment shading, depth testing, or memory bandwidth. Do this before guessing at shader or pass-structure fixes.
+
+The workflow was built and verified on a MediaTek MT6893 (Mali-G77 MC9, r32 driver, TrebleDroid). The vendor library path and counter IDs can differ on other devices; step 2 shows how to list them.
+
+## Prerequisites
+
+- A rooted phone (`adb root` or `su`). Check that `/vendor/lib64/libgpudataproducer.so` exists. This is the vendor library behind Android GPU Inspector's counters.
+- The workload must be **GPU-bound**. Check `/sys/kernel/ged/hal/gpu_utilization` on MediaTek (first field ≥ 90%). Otherwise counter differences say nothing about FPS.
+- Fixed clocks, so cycles are comparable across runs. On MT6893:
+  - GPU: `echo 836000 > /proc/gpufreq/gpufreq_opp_freq`.
+  - CPU: `echo 7 1 > /proc/ppm/policy_status`, then `echo <cluster> <kHz>` into `/proc/ppm/policy/userlimit_{min,max}_cpu_freq`.
+  - The sysfs `scaling_*_freq` files are read-only there.
+  - Restore everything afterwards.
+- Host: the NDK, `protoc`, and a venv with `pip install perfetto` (TraceProcessor downloads its shell binary on first use).
+
+## 1. Start the counter producer
+
+`gpuprod.c` dlopens the vendor library and calls its exported `start()`, which registers the perfetto data source `gpu.counters`.
+
+```sh
+$NDK/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android30-clang -O2 -o gpuprod gpuprod.c
+adb push gpuprod /data/local/tmp/ && adb shell chmod 755 /data/local/tmp/gpuprod
+adb shell 'su -c "getenforce"'          # note the mode to restore later
+adb shell 'su -c "setenforce 0; nohup /data/local/tmp/gpuprod > /data/local/tmp/gpuprod.log 2>&1 &"'
+adb shell perfetto --query | grep gpu.counters   # must list /data/local/tmp/gpuprod
+```
+
+It needs SELinux permissive. **Afterwards**, kill the producer (`su -c "kill $(pidof gpuprod)"`) and restore the mode (`setenforce 1` if it was Enforcing).
+
+## 2. List the counters this GPU offers
+
+A capture without `counter_ids` records nothing, and the IDs are device-specific. Read them from the producer's descriptor:
+
+```sh
+adb exec-out perfetto --query-raw > qraw.bin
+protoc --decode_raw < qraw.bin > qraw.txt
+python3 - <<'P'
+import re
+s = open('qraw.txt').read()
+for i, n in re.findall(r'\n\s*1: (\d+)\n\s*2: "([^"\n]{2,90})"\n\s*3: "', s):
+    print(i, n)
+P
+```
+
+IDs below 65535 are raw hardware counters. IDs 65535 and up are derived expressions (percentages, rates). Prefer raw counters: they add up over time, while ratios don't.
+
+On the Mali-G77 these raw IDs were the useful set:
+
+| ID | Counter | Use |
+|---|---|---|
+| 6 | GPU active cycles | total GPU cost |
+| 196 / 214 | Fragment / non-fragment active cycles | which side the gap is on |
+| 68 | Tiler active cycles | vertex + binning cost |
+| 160 / 175 | Output external read / write beats | DRAM bandwidth |
+| 210 | Tiles | how many tile passes the frame runs (≈ passes × screen tiles) |
+| 211 | Constant tiles killed | tile write-backs eliminated because the tile was unchanged |
+| 254 | Tile buffer write beats to L2 | tile write-back traffic |
+| 203 / 202 | Rasterized / partial rasterized quads | fragment workload size |
+| 204 / 206 | Early ZS tested / killed quads | early depth test working |
+| 207 / 208 | Late ZS tested / killed quads | shaders forced to late ZS (discard, depth writes, clears via shader) |
+| 212 | FPK occluder quads | forward pixel kill |
+| 234 | Texture quads | quads that sample textures |
+| 219 / 220 / 221 / 222 | FMA / CVT / SFU / message instructions | shader instruction mix |
+| 242 / 243 | 32-bit / 16-bit interpolation active | fp32 vs fp16 varyings |
+| 209 | Warps using more than 32 registers | register pressure |
+| 70 / 75 | Triangle / visible primitives | geometry identity check |
+| 85 / 101 | IDVS position / varying shading requests | vertex shading |
+
+`counters.cfg` captures this set: 5 s at a 20 ms sampling period.
+
+## 3. Capture each renderer
+
+Get each renderer into the same steady scene: same camera, frozen world time, same resolution. Then capture while it runs:
+
+```sh
+adb push counters.cfg /data/local/tmp/
+adb shell 'cat /data/local/tmp/counters.cfg | perfetto --txt -c - -o /data/misc/perfetto-traces/cnt.pftrace'
+adb pull /data/misc/perfetto-traces/cnt.pftrace A.pftrace
+```
+
+- Record each run's FPS during the capture (for example, the on-screen FPS counter in a screenshot taken right after).
+- Change only the renderer between captures.
+- Cool the phone between runs and keep the clocks locked.
+
+## 4. Compare per frame
+
+```sh
+python compare.py A.pftrace <fpsA> B.pftrace <fpsB>
+```
+
+It sums each counter over the capture, converts to per second, divides by FPS, and prints A/frame, B/frame and B/A, sorted by A's per-frame cost. Many values come out fractional, because the producer averages per-core counters across shader cores. Only the ratios matter.
+
+## 5. Read the result
+
+Work top-down:
+
+1. **GPU active cycles B/A**: the size of the gap. It should roughly match the FPS ratio when GPU-bound.
+2. **Fragment vs non-fragment active cycles.** Whichever ratio is above 1 holds the gap. Equal vertex counters (non-fragment, tiler, primitives, IDVS) mean the geometry and vertex shading are identical, so look only at fragment work.
+3. **Tiles.** B/A ≈ 1 + k means B renders about k extra full-screen passes per frame. Typical causes:
+   - a standalone clear pass;
+   - a pass split by a mid-frame upload or barrier;
+   - a blit, copy or clear outside a render pass (Mali runs those as fragment jobs too).
+
+   Find them with a per-frame Vulkan command census (see [Census of Magma's Vulkan commands](#census-of-magmas-vulkan-commands)).
+4. **Rasterized quads, late ZS, texture quads.**
+   - With equal tiles: more rasterized quads mean extra full-screen draws inside a pass. For example, `vkCmdClearAttachments` mid-pass costs about one screen of quads each time.
+   - High late-ZS counts mean fragments lost the early depth test: shaders with `discard`, `gl_FragDepth` or `gl_SampleMask` writes, or clears implemented as shader draws.
+   - More early-ZS kills with equal visible primitives often mean the same thing seen from the other side.
+5. **External write beats vs tile buffer write beats.**
+   - If B's extra external writes ≈ extra tile write beats × shader-core count, the difference is tile write-back.
+   - Check `Constant tiles killed`: the GLES driver eliminates write-back of unchanged tiles. A Vulkan path with a much lower count is losing that elimination.
+   - In a static benchmark scene this is a big effect. With a moving camera it is a small one.
+6. **Instruction mix and interpolation.** More FMA or CVT instructions with equal quads point at shader code quality. Much more 32-bit than 16-bit interpolation points at precision: for example, ESSL `mediump` lost when a backend recompiles the shader as desktop GLSL.
+
+## Census of Magma's Vulkan commands
+
+When the tile count says Magma runs extra passes, find out which ones. Use a temporary, never-committed build:
+
+- **Wrappers:** write a header that declares counting wrappers and maps each `vkCmd*` entry point to its wrapper with a function-like macro (`#define vkCmdBeginRenderPass(...) Census_BeginRenderPass(__VA_ARGS__)`). Function-like macros leave function-pointer assignments such as `fns.vkCmdBeginRenderPass = vkCmdBeginRenderPass;` alone.
+  - Include `VK_USE_PLATFORM_ANDROID_KHR` before `<vulkan/vulkan.h>` in that header.
+  - Map at least render pass begin, render pass creation (to record each pass's load/store ops), blit, copy, clear (including `vkCmdClearAttachments`), resolve, dispatch, barrier, submit and present.
+- **Force-include:** apply it only to the DirectVulkan sources:
+
+  ```cmake
+  file(GLOB _census ${CMAKE_CURRENT_SOURCE_DIR}/MobileGL/MG_Backend/DirectVulkan/*.cpp
+                    ${CMAKE_CURRENT_SOURCE_DIR}/MobileGL/MG_Backend/DirectVulkan/Renderer/*.cpp)
+  list(FILTER _census EXCLUDE REGEX "Census")   # the wrapper definitions must call the real entry points
+  set_source_files_properties(${_census} PROPERTIES COMPILE_OPTIONS "-include;<path>/Census.h")
+  ```
+
+- **Recording:** in each wrapper, key the count by kind, the caller's offset in the library (`__builtin_return_address(0)` minus `dladdr`'s `dli_fbase`) and details: render area plus load/store ops for passes, area for clears and blits. In the present wrapper, every few seconds, log the counts divided by the number of frames to logcat.
+- **Symbolize** the offsets against the unstripped library: `llvm-addr2line -f -C -i -e build/intermediates/cxx/RelWithDebInfo/*/obj/arm64-v8a/libMobileGL.so 0x<offset>`. The library under `stripped_native_libs` has no symbols. If a wrapper's caller is a shared helper, log `__builtin_return_address(1..5)` inside that helper; arm64 Android keeps frame pointers.
+
+## Example: Magma vs the system driver
+
+Minecraft 1.12.2 with OptiFine at 2400×1080 on a Mali-G77, clocks locked, SFPEW over each backend:
+
+| Finding | Counters | Cause | Fix |
+|---|---|---|---|
+| Fragment active cycles 1.33×, tiles 1.46× | rasterized quads, late ZS and tiles all up; vertex counters equal | one extra full-screen depth-only pass per frame (census: `vkCmdBeginRenderPass` with only `D24S8` LOAD/STORE, plus a full-screen `vkCmdClearAttachments`) | a window clear with a window pass open now ends the pass and folds into the next one (`VulkanRenderer::DeferDefaultWireClear`) |
+| Extra external writes 1.7× | tile buffer write beats ≈ 23×, constant tiles killed 0.07× | the GLES driver eliminates the write-back of unchanged tiles in a static scene; Magma's attachments get none | still open |
+| Fragment cycles still 1.18× with equal tiles | rasterized quads 1.26×, late ZS 1.44× | the game's two in-pass depth clears per frame, recorded as full-screen `vkCmdClearAttachments` | under investigation |
+
+Separately, SFPEW hands MobileGL ESSL with `precision mediump float;` inside `#ifdef GL_ES`. The source processor rewrites ESSL to desktop GLSL with `GL_ES` undefined, so that guard silently turned the shaders fp32. 16-bit interpolation counters and the RelaxedPrecision decorations in the SPIR-V show this kind of loss.
+
+## Pitfalls
+
+- **Unlocked clocks.** Cycle counts are only comparable at the same GPU frequency, and FPS also depends on the CPU clock when the workload is not fully GPU-bound.
+- **Not checking the build.** Before comparing builds, verify that each run actually ran the build you think it did. `adb install -r` of an APK with a lower versionCode fails with `INSTALL_FAILED_VERSION_DOWNGRADE`, and the run silently uses whatever was installed.
+- **Different scenes.** Counters from different scenes or camera angles are not comparable at all. Freeze world time and camera position between runs.
+- **Leaving the phone modified.** The producer and permissive SELinux stay in place until you undo them. Restore both, and the clock locks, when you are done.

docs/Performance/mali-gpu-counters/compare.py

@@ -0,0 +1,34 @@
+"""Per-frame comparison of two Mali counter captures.
+
+usage: python compare.py A.pftrace FPS_A B.pftrace FPS_B
+Needs `pip install perfetto`.
+"""
+import sys
+
+from perfetto.trace_processor import TraceProcessor
+
+
+def per_second(path):
+    tp = TraceProcessor(trace=path)
+    rows = tp.query(
+        "select t.name, sum(c.value) s, (max(c.ts) - min(c.ts)) / 1e9 dur "
+        "from gpu_counter_track t join counter c on c.track_id = t.id group by t.id")
+    out = {r.name: r.s / r.dur for r in rows if r.dur > 0}
+    tp.close()
+    return out
+
+
+def main():
+    if len(sys.argv) != 5:
+        sys.exit(__doc__)
+    a, fps_a, b, fps_b = sys.argv[1], float(sys.argv[2]), sys.argv[3], float(sys.argv[4])
+    A, B = per_second(a), per_second(b)
+    print(f"{'counter':52s} {'A/frame':>14s} {'B/frame':>14s} {'B/A':>6s}")
+    for name in sorted(A, key=lambda k: -A[k] / fps_a):
+        pa, pb = A[name] / fps_a, B.get(name, 0.0) / fps_b
+        ratio = f"{pb / pa:6.2f}" if pa else "   n/a"
+        print(f"{name:52s} {pa:14.0f} {pb:14.0f} {ratio}")
+
+
+if __name__ == "__main__":
+    main()

docs/Performance/mali-gpu-counters/counters.cfg

@@ -0,0 +1,50 @@
+# Mali-G77 raw counters (IDs from step 2 of SKILL.md); 5 s at a 20 ms period.
+buffers { size_kb: 131072 fill_policy: DISCARD }
+data_sources { config { name: "gpu.counters" gpu_counter_config { counter_period_ns: 20000000
+  counter_ids: 6
+  counter_ids: 10
+  counter_ids: 18
+  counter_ids: 196
+  counter_ids: 214
+  counter_ids: 68
+  counter_ids: 160
+  counter_ids: 175
+  counter_ids: 218
+  counter_ids: 219
+  counter_ids: 220
+  counter_ids: 221
+  counter_ids: 222
+  counter_ids: 245
+  counter_ids: 201
+  counter_ids: 216
+  counter_ids: 203
+  counter_ids: 202
+  counter_ids: 204
+  counter_ids: 206
+  counter_ids: 207
+  counter_ids: 208
+  counter_ids: 212
+  counter_ids: 210
+  counter_ids: 211
+  counter_ids: 254
+  counter_ids: 250
+  counter_ids: 251
+  counter_ids: 231
+  counter_ids: 234
+  counter_ids: 241
+  counter_ids: 242
+  counter_ids: 243
+  counter_ids: 247
+  counter_ids: 248
+  counter_ids: 249
+  counter_ids: 70
+  counter_ids: 75
+  counter_ids: 85
+  counter_ids: 101
+  counter_ids: 209
+  counter_ids: 8
+  counter_ids: 16
+  counter_ids: 226
+  counter_ids: 223
+} } }
+duration_ms: 5000

docs/Performance/mali-gpu-counters/gpuprod.c

@@ -0,0 +1,26 @@
+/*
+ * Starts the vendor Mali counter producer so perfetto can record the
+ * "gpu.counters" data source. Run as root, with SELinux permissive.
+ *
+ * Build: aarch64-linux-android30-clang -O2 -o gpuprod gpuprod.c
+ */
+#include <dlfcn.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main(void) {
+    void* lib = dlopen("/vendor/lib64/libgpudataproducer.so", RTLD_NOW);
+    if (!lib) {
+        fprintf(stderr, "dlopen: %s\n", dlerror());
+        return 1;
+    }
+    void (*start)(void) = (void (*)(void))dlsym(lib, "start");
+    if (!start) {
+        fprintf(stderr, "libgpudataproducer.so exports no start()\n");
+        return 1;
+    }
+    fprintf(stderr, "starting producer\n");
+    start();
+    for (;;)
+        pause();
+}