D3D12: Initial commit for D3D12 backend implementation.

Source/Core/VideoBackends/D3D12/PerfQuery.h

@@ -0,0 +1,46 @@
+// Copyright 2012 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <array>
+
+#include "VideoCommon/PerfQueryBase.h"
+
+namespace DX12
+{
+
+class PerfQuery final : public PerfQueryBase
+{
+public:
+	PerfQuery();
+	~PerfQuery();
+
+	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
+	{
+		ID3D11Query* query;
+		PerfQueryGroup query_type;
+	};
+
+	void WeakFlush();
+
+	// Only use when non-empty
+	void FlushOne();
+
+	// when testing in SMS: 64 was too small, 128 was ok
+	static const int s_perf_query_buffer_size = 512;
+
+	std::array<ActiveQuery, s_perf_query_buffer_size> m_query_buffer;
+	int m_query_read_pos = 0;
+};
+
+} // namespace