Implement experimental Vulkan backend

Source/Core/VideoBackends/Vulkan/PerfQuery.h

@@ -0,0 +1,70 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+#include <memory>
+
+#include "VideoBackends/Vulkan/Constants.h"
+#include "VideoCommon/PerfQueryBase.h"
+
+namespace Vulkan
+{
+class StagingBuffer;
+class StateTracker;
+
+class PerfQuery : public PerfQueryBase
+{
+public:
+  PerfQuery();
+  ~PerfQuery();
+
+  bool Initialize(StateTracker* state_tracker);
+
+  void EnableQuery(PerfQueryGroup type) override;
+  void DisableQuery(PerfQueryGroup type) override;
+  void ResetQuery() override;
+  u32 GetQueryResult(PerfQueryType type) override;
+  void FlushResults() override;
+  bool IsFlushed() const override;
+
+private:
+  struct ActiveQuery
+  {
+    PerfQueryType query_type;
+    VkFence pending_fence;
+    bool available;
+    bool active;
+  };
+
+  bool CreateQueryPool();
+  bool CreateReadbackBuffer();
+  void QueueCopyQueryResults(VkCommandBuffer command_buffer, VkFence fence, u32 start_index,
+                             u32 query_count);
+  void ProcessResults(u32 start_index, u32 query_count);
+
+  void OnCommandBufferQueued(VkCommandBuffer command_buffer, VkFence fence);
+  void OnCommandBufferExecuted(VkFence fence);
+
+  void NonBlockingPartialFlush();
+  void BlockingPartialFlush();
+
+  StateTracker* m_state_tracker = nullptr;
+
+  // when testing in SMS: 64 was too small, 128 was ok
+  // TODO: This should be size_t, but the base class uses u32s
+  using PerfQueryDataType = u32;
+  static const u32 PERF_QUERY_BUFFER_SIZE = 512;
+  std::array<ActiveQuery, PERF_QUERY_BUFFER_SIZE> m_query_buffer = {};
+  u32 m_query_read_pos = 0;
+
+  // TODO: Investigate using pipeline statistics to implement other query types
+  VkQueryPool m_query_pool = VK_NULL_HANDLE;
+
+  // Buffer containing query results. Each query is a u32.
+  std::unique_ptr<StagingBuffer> m_readback_buffer;
+};
+
+}  // namespace Vulkan