D3D12: Keep a reference to pipelines until unused

Previously we would remove the reference to pipelines in the destructor
of the d3d12::*Pipeline objects which could cause the D3D12 pipeline
state to be destroyed while still used by in-flight commands. Add a
global queue of ComPtrs to keep alive in the d3d12::Device to fix this.

src/backend/d3d12/ComputePipelineD3D12.cpp

@@ -24,7 +24,7 @@
 namespace backend { namespace d3d12 {
 
     ComputePipeline::ComputePipeline(ComputePipelineBuilder* builder)
-        : ComputePipelineBase(builder) {
+        : ComputePipelineBase(builder), mDevice(ToBackend(builder->GetDevice())) {
         uint32_t compileFlags = 0;
 #if defined(_DEBUG)
         // Enable better shader debugging with the graphics debugging tools.
@@ -57,6 +57,10 @@ namespace backend { namespace d3d12 {
                                                              IID_PPV_ARGS(&mPipelineState));
     }
 
+    ComputePipeline::~ComputePipeline() {
+        mDevice->ReferenceUntilUnused(mPipelineState);
+    }
+
     ComPtr<ID3D12PipelineState> ComputePipeline::GetPipelineState() {
         return mPipelineState;
     }

src/backend/d3d12/ComputePipelineD3D12.h

@@ -21,14 +21,18 @@
 
 namespace backend { namespace d3d12 {
 
+    class Device;
+
     class ComputePipeline : public ComputePipelineBase {
       public:
         ComputePipeline(ComputePipelineBuilder* builder);
+        ~ComputePipeline();
 
         ComPtr<ID3D12PipelineState> GetPipelineState();
 
       private:
         ComPtr<ID3D12PipelineState> mPipelineState;
+        Device* mDevice = nullptr;
     };
 
 }}  // namespace backend::d3d12

src/backend/d3d12/D3D12Backend.cpp

@@ -149,6 +149,8 @@ namespace backend { namespace d3d12 {
         NextSerial();
         WaitForSerial(currentSerial);  // Wait for all in-flight commands to finish executing
         TickImpl();                    // Call tick one last time so resources are cleaned up
+        ASSERT(mUsedComObjectRefs.Empty());
+
         delete mCommandAllocatorManager;
         delete mDescriptorHeapAllocator;
         delete mMapReadRequestTracker;
@@ -214,6 +216,7 @@ namespace backend { namespace d3d12 {
         mCommandAllocatorManager->Tick(lastCompletedSerial);
         mDescriptorHeapAllocator->Tick(lastCompletedSerial);
         mMapReadRequestTracker->Tick(lastCompletedSerial);
+        mUsedComObjectRefs.ClearUpTo(lastCompletedSerial);
         ExecuteCommandLists({});
         NextSerial();
     }
@@ -234,6 +237,10 @@ namespace backend { namespace d3d12 {
         }
     }
 
+    void Device::ReferenceUntilUnused(ComPtr<IUnknown> object) {
+        mUsedComObjectRefs.Enqueue(object, mSerial);
+    }
+
     void Device::ExecuteCommandLists(std::initializer_list<ID3D12CommandList*> commandLists) {
         // If there are pending commands, prepend them to ExecuteCommandLists
         if (mPendingCommands.open) {

src/backend/d3d12/D3D12Backend.h

@@ -21,8 +21,8 @@
 #include "backend/Device.h"
 #include "backend/RenderPass.h"
 #include "backend/ToBackend.h"
-
 #include "backend/d3d12/d3d12_platform.h"
+#include "common/SerialQueue.h"
 
 namespace backend { namespace d3d12 {
 
@@ -127,6 +127,8 @@ namespace backend { namespace d3d12 {
         void NextSerial();
         void WaitForSerial(uint64_t serial);
 
+        void ReferenceUntilUnused(ComPtr<IUnknown> object);
+
         void ExecuteCommandLists(std::initializer_list<ID3D12CommandList*> commandLists);
 
       private:
@@ -149,6 +151,8 @@ namespace backend { namespace d3d12 {
             ComPtr<ID3D12GraphicsCommandList> commandList;
             bool open = false;
         } mPendingCommands;
+
+        SerialQueue<ComPtr<IUnknown>> mUsedComObjectRefs;
     };
 
     class RenderPass : public RenderPassBase {

src/backend/d3d12/RenderPipelineD3D12.cpp

@@ -64,7 +64,8 @@ namespace backend { namespace d3d12 {
 
     RenderPipeline::RenderPipeline(RenderPipelineBuilder* builder)
         : RenderPipelineBase(builder),
-          mD3d12PrimitiveTopology(D3D12PrimitiveTopology(GetPrimitiveTopology())) {
+          mD3d12PrimitiveTopology(D3D12PrimitiveTopology(GetPrimitiveTopology())),
+          mDevice(ToBackend(builder->GetDevice())) {
         uint32_t compileFlags = 0;
 #if defined(_DEBUG)
         // Enable better shader debugging with the graphics debugging tools.
@@ -171,6 +172,10 @@ namespace backend { namespace d3d12 {
             &descriptor, IID_PPV_ARGS(&mPipelineState)));
     }
 
+    RenderPipeline::~RenderPipeline() {
+        mDevice->ReferenceUntilUnused(mPipelineState);
+    }
+
     D3D12_PRIMITIVE_TOPOLOGY RenderPipeline::GetD3D12PrimitiveTopology() const {
         return mD3d12PrimitiveTopology;
     }

src/backend/d3d12/RenderPipelineD3D12.h

@@ -21,9 +21,12 @@
 
 namespace backend { namespace d3d12 {
 
+    class Device;
+
     class RenderPipeline : public RenderPipelineBase {
       public:
         RenderPipeline(RenderPipelineBuilder* builder);
+        ~RenderPipeline();
 
         D3D12_PRIMITIVE_TOPOLOGY GetD3D12PrimitiveTopology() const;
         ComPtr<ID3D12PipelineState> GetPipelineState();
@@ -31,6 +34,8 @@ namespace backend { namespace d3d12 {
       private:
         D3D12_PRIMITIVE_TOPOLOGY mD3d12PrimitiveTopology;
         ComPtr<ID3D12PipelineState> mPipelineState;
+
+        Device* mDevice = nullptr;
     };
 
 }}  // namespace backend::d3d12