Unify three types of non-FIFO requests to the GPU thread around Common::Event and Common::Flag.

The only possible functionality change is that s_efbAccessRequested and
s_swapRequested are no longer reset at init and shutdown of the OGL
backend (only; this is the only interaction any files other than
MainBase.cpp have with them).  I am fairly certain this was entirely
vestigial.

Possible performance implications: efbAccessReady now uses an Event
rather than spinning, which might be slightly slower, but considering
the slow loop the flags are being checked in from the GPU thread, I
doubt it's noticeable.

Also, this uses sequentially consistent rather than release/acquire
memory order, which might be slightly slower, especially on ARM...
something to improve in Event/Flag, really.

Source/Core/VideoBackends/D3D/main.cpp

@@ -160,11 +160,6 @@ bool VideoBackend::Initialize(void *window_handle)
 
 void VideoBackend::Video_Prepare()
 {
-	// Better be safe...
-	s_efbAccessRequested = FALSE;
-	s_FifoShuttingDown = FALSE;
-	s_swapRequested = FALSE;
-
 	// internal interfaces
 	g_renderer = new Renderer(m_window_handle);
 	g_texture_cache = new TextureCache;
@@ -196,10 +191,6 @@ void VideoBackend::Shutdown()
 	// TODO: should be in Video_Cleanup
 	if (g_renderer)
 	{
-		s_efbAccessRequested = FALSE;
-		s_FifoShuttingDown = FALSE;
-		s_swapRequested = FALSE;
-
 		// VideoCommon
 		Fifo_Shutdown();
 		CommandProcessor::Shutdown();

Source/Core/VideoBackends/OGL/main.cpp

@@ -189,10 +189,6 @@ void VideoBackend::Video_Prepare()
 
 	g_renderer = new Renderer;
 
-	s_efbAccessRequested = false;
-	s_FifoShuttingDown = false;
-	s_swapRequested = false;
-
 	CommandProcessor::Init();
 	PixelEngine::Init();
 
@@ -230,9 +226,6 @@ void VideoBackend::Video_Cleanup()
 {
 	if (g_renderer)
 	{
-		s_efbAccessRequested = false;
-		s_FifoShuttingDown = false;
-		s_swapRequested = false;
 		Fifo_Shutdown();
 
 		// The following calls are NOT Thread Safe

Source/Core/VideoCommon/MainBase.cpp

@@ -1,5 +1,4 @@
-
+#include "Common/Event.h"
-#include "Common/Atomic.h"
 #include "Core/ConfigManager.h"
 
 #include "VideoCommon/BPStructs.h"
@@ -18,13 +17,13 @@
 
 bool s_BackendInitialized = false;
 
-volatile u32 s_swapRequested = false;
+Common::Flag s_swapRequested;
-u32 s_efbAccessRequested = false;
+static Common::Flag s_FifoShuttingDown;
-volatile u32 s_FifoShuttingDown = false;
+static Common::Flag s_efbAccessRequested;
+static Common::Event s_efbAccessReadyEvent;
 
-static std::condition_variable s_perf_query_cond;
+static Common::Flag s_perfQueryRequested;
-static std::mutex s_perf_query_lock;
+static Common::Event s_perfQueryReadyEvent;
-static volatile bool s_perf_query_requested;
 
 static volatile struct
 {
@@ -57,7 +56,9 @@ void VideoBackendHardware::Video_EnterLoop()
 void VideoBackendHardware::Video_ExitLoop()
 {
 	ExitGpuLoop();
-	s_FifoShuttingDown = true;
+	s_FifoShuttingDown.Set();
+	s_efbAccessReadyEvent.Set();
+	s_perfQueryReadyEvent.Set();
 }
 
 void VideoBackendHardware::Video_SetRendering(bool bEnabled)
@@ -70,11 +71,11 @@ static void VideoFifo_CheckSwapRequest()
 {
 	if (g_ActiveConfig.bUseXFB)
 	{
-		if (Common::AtomicLoadAcquire(s_swapRequested))
+		if (s_swapRequested.IsSet())
 		{
 			EFBRectangle rc;
 			Renderer::Swap(s_beginFieldArgs.xfbAddr, s_beginFieldArgs.fbWidth, s_beginFieldArgs.fbHeight,rc);
-			Common::AtomicStoreRelease(s_swapRequested, false);
+			s_swapRequested.Clear();
 		}
 	}
 }
@@ -84,7 +85,7 @@ void VideoFifo_CheckSwapRequestAt(u32 xfbAddr, u32 fbWidth, u32 fbHeight)
 {
 	if (g_ActiveConfig.bUseXFB)
 	{
-		if (Common::AtomicLoadAcquire(s_swapRequested))
+		if (s_swapRequested.IsSet())
 		{
 			u32 aLower = xfbAddr;
 			u32 aUpper = xfbAddr + 2 * fbWidth * fbHeight;
@@ -115,7 +116,7 @@ void VideoBackendHardware::Video_EndField()
 {
 	if (s_BackendInitialized)
 	{
-		Common::AtomicStoreRelease(s_swapRequested, true);
+		s_swapRequested.Set();
 	}
 }
 
@@ -138,11 +139,11 @@ bool VideoBackendHardware::Video_Screenshot(const std::string& filename)
 
 void VideoFifo_CheckEFBAccess()
 {
-	if (Common::AtomicLoadAcquire(s_efbAccessRequested))
+	if (s_efbAccessRequested.IsSet())
 	{
 		s_AccessEFBResult = g_renderer->AccessEFB(s_accessEFBArgs.type, s_accessEFBArgs.x, s_accessEFBArgs.y, s_accessEFBArgs.Data);
-
+		s_efbAccessRequested.Clear();
-		Common::AtomicStoreRelease(s_efbAccessRequested, false);
+		s_efbAccessReadyEvent.Set();
 	}
 }
 
@@ -155,13 +156,15 @@ u32 VideoBackendHardware::Video_AccessEFB(EFBAccessType type, u32 x, u32 y, u32
 		s_accessEFBArgs.y = y;
 		s_accessEFBArgs.Data = InputData;
 
-		Common::AtomicStoreRelease(s_efbAccessRequested, true);
+		s_efbAccessRequested.Set();
 
 		if (SConfig::GetInstance().m_LocalCoreStartupParameter.bCPUThread)
 		{
-			while (Common::AtomicLoadAcquire(s_efbAccessRequested) && !s_FifoShuttingDown)
+			s_efbAccessReadyEvent.Reset();
-				//Common::SleepCurrentThread(1);
+			if (s_FifoShuttingDown.IsSet())
-				Common::YieldCPU();
+				return 0;
+			s_efbAccessRequested.Set();
+			s_efbAccessReadyEvent.Wait();
 		}
 		else
 			VideoFifo_CheckEFBAccess();
@@ -172,23 +175,13 @@ u32 VideoBackendHardware::Video_AccessEFB(EFBAccessType type, u32 x, u32 y, u32
 	return 0;
 }
 
-static bool QueryResultIsReady()
-{
-	return !s_perf_query_requested || s_FifoShuttingDown;
-}
-
 static void VideoFifo_CheckPerfQueryRequest()
 {
-	if (s_perf_query_requested)
+	if (s_perfQueryRequested.IsSet())
 	{
 		g_perf_query->FlushResults();
-
+		s_perfQueryRequested.Clear();
-		{
+		s_perfQueryReadyEvent.Set();
-		std::lock_guard<std::mutex> lk(s_perf_query_lock);
-		s_perf_query_requested = false;
-		}
-
-		s_perf_query_cond.notify_one();
 	}
 }
 
@@ -204,9 +197,11 @@ u32 VideoBackendHardware::Video_GetQueryResult(PerfQueryType type)
 	{
 		if (SConfig::GetInstance().m_LocalCoreStartupParameter.bCPUThread)
 		{
-			s_perf_query_requested = true;
+			s_perfQueryReadyEvent.Reset();
-			std::unique_lock<std::mutex> lk(s_perf_query_lock);
+			if (s_FifoShuttingDown.IsSet())
-			s_perf_query_cond.wait(lk, QueryResultIsReady);
+				return 0;
+			s_perfQueryRequested.Set();
+			s_perfQueryReadyEvent.Wait();
 		}
 		else
 			g_perf_query->FlushResults();
@@ -219,10 +214,10 @@ void VideoBackendHardware::InitializeShared()
 {
 	VideoCommon_Init();
 
-	s_swapRequested = 0;
+	s_swapRequested.Clear();
-	s_efbAccessRequested = 0;
+	s_efbAccessRequested.Clear();
-	s_perf_query_requested = false;
+	s_perfQueryRequested.Clear();
-	s_FifoShuttingDown = 0;
+	s_FifoShuttingDown.Clear();
 	memset((void*)&s_beginFieldArgs, 0, sizeof(s_beginFieldArgs));
 	memset(&s_accessEFBArgs, 0, sizeof(s_accessEFBArgs));
 	s_AccessEFBResult = 0;

Source/Core/VideoCommon/MainBase.h

@@ -1,11 +1,10 @@
 #pragma once
 
 #include "Common/CommonTypes.h"
+#include "Common/Flag.h"
 
 extern bool s_BackendInitialized;
-extern u32 s_efbAccessRequested;
+extern Common::Flag s_swapRequested;
-extern volatile u32 s_FifoShuttingDown;
-extern volatile u32 s_swapRequested;
 
 void VideoFifo_CheckEFBAccess();
 void VideoFifo_CheckSwapRequestAt(u32 xfbAddr, u32 fbWidth, u32 fbHeight);

Source/Core/VideoCommon/RenderBase.cpp

@@ -126,7 +126,7 @@ void Renderer::RenderToXFB(u32 xfbAddr, const EFBRectangle& sourceRc, u32 fbWidt
 	else
 	{
 		Swap(xfbAddr, fbWidth, fbHeight,sourceRc,Gamma);
-		Common::AtomicStoreRelease(s_swapRequested, false);
+		s_swapRequested.Clear();
 	}
 }