fixup! CoreTiming: Keep Cores synced by having each core it's own downcount and let the main core run an intermediate run if it's slice_length was cropped

src/core/core_cpu.cpp

@@ -25,7 +25,7 @@ void CpuBarrier::NotifyEnd() {
     condition.notify_all();
 }
 
-bool CpuBarrier::Rendezvous() {
+bool CpuBarrier::Rendezvous(bool main_core) {
     if (!Settings::values.use_multi_core) {
         // Meaningless when running in single-core mode
         return true;
@@ -36,7 +36,7 @@ bool CpuBarrier::Rendezvous() {
 
         --cores_waiting;
         if (!cores_waiting) {
-            if (CoreTiming::MainSliceWasCropped() && IsMainCore()) {
+            if (CoreTiming::MainSliceWasCropped() && main_core) {
                 // This is the main thread but we were cropped, so just continue;
                 ++cores_waiting;
                 return true;
@@ -46,7 +46,7 @@ bool CpuBarrier::Rendezvous() {
             return true;
         }
 
-        if (CoreTiming::MainSliceWasCropped() && IsMainCore()) {
+        if (CoreTiming::MainSliceWasCropped() && main_core) {
             // This is the main thread but we were cropped, so just continue;
             ++cores_waiting;
             return true;
@@ -90,7 +90,7 @@ std::shared_ptr<ExclusiveMonitor> Cpu::MakeExclusiveMonitor(size_t num_cores) {
 
 void Cpu::RunLoop(bool tight_loop) {
     // Wait for all other CPU cores to complete the previous slice, such that they run in lock-step
-    if (!cpu_barrier->Rendezvous()) {
+    if (!cpu_barrier->Rendezvous(IsMainCore())) {
         // If rendezvous failed, session has been killed
         return;
     }

src/core/core_cpu.h

@@ -30,7 +30,7 @@ public:
 
     void NotifyEnd();
 
-    bool Rendezvous();
+    bool Rendezvous(bool main_core);
 
 private:
     unsigned cores_waiting{NUM_CPU_CORES};

src/core/core_timing.cpp

@@ -93,7 +93,7 @@ void UnregisterAllEvents() {
 
 void Init() {
     std::unique_lock<std::mutex> lock(mutex);
-    std::fill(downcount.begin(), downcount.end(), MAX_SLICE_LENGTH);
+    downcount.fill(MAX_SLICE_LENGTH);
     slice_length = MAX_SLICE_LENGTH;
     next_slice_length = MAX_SLICE_LENGTH;
     global_timer = 0;
@@ -183,8 +183,7 @@ void ForceExceptionCheck(s64 cycles) {
     if (downcount[0] > cycles) {
         // downcount is always (much) smaller than MAX_INT so we can safely cast cycles to an int
         // here. Account for cycles already executed by adjusting the g.slice_length
-        s64 crop_time = downcount[0] - static_cast<int>(cycles);
-        slice_length -= crop_time;
+        slice_length -= downcount[0] - static_cast<int>(cycles);
         downcount[0] = static_cast<int>(cycles);
         if (next_slice_length <= 0)
             next_slice_length = MAX_SLICE_LENGTH;
@@ -201,7 +200,7 @@ void MoveEvents() {
 
 void Advance() {
     std::unique_lock<std::mutex> lock(mutex);
-    size_t current_core = Core::System::GetInstance().CurrentCoreIndex();
+    const size_t current_core = Core::System::GetInstance().CurrentCoreIndex();
     if (current_core != 0) {
         downcount[current_core] = MAX_SLICE_LENGTH;
         return;

src/core/core_timing.h

@@ -81,6 +81,7 @@ void MoveEvents();
 /// Pretend that the main CPU has executed enough cycles to reach the next event.
 void Idle();
 
+/// Checks if the Main Core executed less then MAX_SLICE_LENGTH
 bool MainSliceWasCropped();
 
 /// Clear all pending events. This should ONLY be done on exit.