From 567976e822fb26e2ad75ae299962632546b54399 Mon Sep 17 00:00:00 2001
From: Gregory Hainaut <gregory.hainaut@gmail.com>
Date: Sun, 3 Jul 2016 11:12:35 +0200
Subject: [PATCH] MTVU: port vuCycles to std::atomic

V2: use relaxed order as the variable doesn't carry load/store dependency
It is only used as a counter for the speed hack
---
 pcsx2/MTVU.cpp | 16 +++++++++++-----
 pcsx2/MTVU.h   |  2 +-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/pcsx2/MTVU.cpp b/pcsx2/MTVU.cpp
index 875e38a672..ee85811ea8 100644
--- a/pcsx2/MTVU.cpp
+++ b/pcsx2/MTVU.cpp
@@ -52,7 +52,10 @@ void SaveStateBase::mtvuFreeze()
 	FreezeTag("MTVU");
 	pxAssert(vu1Thread.IsDone());
 	if (!IsSaving()) vu1Thread.Reset();
-	Freeze(vu1Thread.vuCycles);
+	for (size_t i = 0; i < 4; ++i) {
+		unsigned int v = vu1Thread.vuCycles[i].load();
+		Freeze(v);
+	}
 	Freeze(vu1Thread.vuCycleIdx);
 }
 
@@ -82,7 +85,8 @@ void VU_Thread::Reset()
 	write_pos    = 0;
 	memzero(vif);
 	memzero(vifRegs);
-	memzero(vuCycles);
+	for (size_t i = 0; i < 4; ++i)
+		vu1Thread.vuCycles[i] = 0;
 }
 
 void VU_Thread::ExecuteTaskInThread()
@@ -109,7 +113,7 @@ void VU_Thread::ExecuteRingBuffer()
 					vuCPU->Execute(vu1RunCycles);
 					gifUnit.gifPath[GIF_PATH_1].FinishGSPacketMTVU();
 					semaXGkick.Post(); // Tell MTGS a path1 packet is complete
-					AtomicExchange(vuCycles[vuCycleIdx], vuRegs.cycle);
+					vuCycles[vuCycleIdx].store(vuRegs.cycle, std::memory_order_relaxed);
 					vuCycleIdx  = (vuCycleIdx + 1) & 3;
 					break;
 				}
@@ -265,8 +269,10 @@ __fi void VU_Thread::WriteRegs(VIFregisters* src)
 // Used for vu cycle stealing hack
 u32 VU_Thread::Get_vuCycles()
 {
-	return (AtomicRead(vuCycles[0]) + AtomicRead(vuCycles[1])
-		  + AtomicRead(vuCycles[2]) + AtomicRead(vuCycles[3])) >> 2;
+	return (vuCycles[0].load(std::memory_order_relaxed) +
+			vuCycles[1].load(std::memory_order_relaxed) +
+			vuCycles[2].load(std::memory_order_relaxed) +
+			vuCycles[3].load(std::memory_order_relaxed)) >> 2;
 }
 
 void VU_Thread::KickStart(bool forceKick)
diff --git a/pcsx2/MTVU.h b/pcsx2/MTVU.h
index e6e045c04b..71d16c5ce9 100644
--- a/pcsx2/MTVU.h
+++ b/pcsx2/MTVU.h
@@ -43,7 +43,7 @@ public:
 	__aligned16  vifStruct        vif;
 	__aligned16  VIFregisters     vifRegs;
 	__aligned(4) Semaphore semaXGkick;
-	__aligned(4) u32 vuCycles[4]; // Used for VU cycle stealing hack
+	__aligned(4) std::atomic<unsigned int> vuCycles[4]; // Used for VU cycle stealing hack
 	__aligned(4) u32 vuCycleIdx;  // Used for VU cycle stealing hack
 
 	VU_Thread(BaseVUmicroCPU*& _vuCPU, VURegs& _vuRegs);