Initial conditional rendering support (#1012)

* Initial conditional rendering support

* Properly reset state

* Support conditional modes and skeleton a counter cache for future host conditional rendering

* Address PR feedback

Ryujinx.Graphics.Gpu/Engine/MethodClear.cs

@@ -13,6 +13,11 @@ namespace Ryujinx.Graphics.Gpu.Engine
         /// <param name="argument">Method call argument</param>
         private void Clear(GpuState state, int argument)
         {
+            if (!GetRenderEnable(state))
+            {
+                return;
+            }
+
             // Scissor affects clears aswell.
             if (state.QueryModified(MethodOffset.ScissorState))
             {

Ryujinx.Graphics.Gpu/Engine/MethodConditionalRendering.cs

@@ -0,0 +1,82 @@
+using Ryujinx.Common.Logging;
+using Ryujinx.Graphics.Gpu.State;
+
+namespace Ryujinx.Graphics.Gpu.Engine
+{
+    partial class Methods
+    {
+        /// <summary>
+        /// Checks if draws and clears should be performed, according
+        /// to currently set conditional rendering conditions.
+        /// </summary>
+        /// <param name="state">GPU state</param>
+        /// <returns>True if rendering is enabled, false otherwise</returns>
+        private bool GetRenderEnable(GpuState state)
+        {
+            ConditionState condState = state.Get<ConditionState>(MethodOffset.ConditionState);
+
+            switch (condState.Condition)
+            {
+                case Condition.Always:
+                    return true;
+                case Condition.Never:
+                    return false;
+                case Condition.ResultNonZero:
+                    return CounterNonZero(condState.Address.Pack());
+                case Condition.Equal:
+                    return CounterCompare(condState.Address.Pack(), true);
+                case Condition.NotEqual:
+                    return CounterCompare(condState.Address.Pack(), false);
+            }
+
+            Logger.PrintWarning(LogClass.Gpu, $"Invalid conditional render condition \"{condState.Condition}\".");
+
+            return true;
+        }
+
+        /// <summary>
+        /// Checks if the counter value at a given GPU memory address is non-zero.
+        /// </summary>
+        /// <param name="gpuVa">GPU virtual address of the counter value</param>
+        /// <returns>True if the value is not zero, false otherwise</returns>
+        private bool CounterNonZero(ulong gpuVa)
+        {
+            if (!FindAndFlush(gpuVa))
+            {
+                return false;
+            }
+
+            return _context.MemoryAccessor.ReadUInt64(gpuVa) != 0;
+        }
+
+        /// <summary>
+        /// Checks if the counter at a given GPU memory address passes a specified equality comparison.
+        /// </summary>
+        /// <param name="gpuVa">GPU virtual address</param>
+        /// <param name="isEqual">True to check if the values are equal, false to check if they are not equal</param>
+        /// <returns>True if the condition is met, false otherwise</returns>
+        private bool CounterCompare(ulong gpuVa, bool isEqual)
+        {
+            if (!FindAndFlush(gpuVa) && !FindAndFlush(gpuVa + 16))
+            {
+                return false;
+            }
+
+            ulong x = _context.MemoryAccessor.ReadUInt64(gpuVa);
+            ulong y = _context.MemoryAccessor.ReadUInt64(gpuVa + 16);
+
+            return isEqual ? x == y : x != y;
+        }
+
+        /// <summary>
+        /// Tries to find a counter that is supposed to be written at the specified address,
+        /// flushing if necessary.
+        /// </summary>
+        /// <param name="gpuVa">GPU virtual address where the counter is supposed to be written</param>
+        /// <returns>True if a counter value is found at the specified address, false otherwise</returns>
+        private bool FindAndFlush(ulong gpuVa)
+        {
+            return _counterCache.Contains(gpuVa);
+        }
+    }
+}

Ryujinx.Graphics.Gpu/Engine/MethodDraw.cs

@@ -35,8 +35,15 @@ namespace Ryujinx.Graphics.Gpu.Engine
         /// <param name="argument">Method call argument</param>
         private void DrawEnd(GpuState state, int argument)
         {
-            if (_instancedDrawPending)
+            bool renderEnable = GetRenderEnable(state);
+
+            if (!renderEnable || _instancedDrawPending)
             {
+                if (!renderEnable)
+                {
+                    PerformDeferredDraws();
+                }
+
                 _drawIndexed = false;
 
                 return;

Ryujinx.Graphics.Gpu/Engine/MethodReport.cs

@@ -1,5 +1,6 @@
 using Ryujinx.Common;
 using Ryujinx.Graphics.GAL;
+using Ryujinx.Graphics.Gpu.Memory;
 using Ryujinx.Graphics.Gpu.State;
 using System;
 using System.Runtime.InteropServices;
@@ -11,6 +12,10 @@ namespace Ryujinx.Graphics.Gpu.Engine
         private const int NsToTicksFractionNumerator   = 384;
         private const int NsToTicksFractionDenominator = 625;
 
+        private ulong _runningCounter;
+
+        private readonly CounterCache _counterCache = new CounterCache();
+
         /// <summary>
         /// Writes a GPU counter to guest memory.
         /// </summary>
@@ -98,6 +103,8 @@ namespace Ryujinx.Graphics.Gpu.Engine
             var rs = state.Get<ReportState>(MethodOffset.ReportState);
 
             _context.MemoryAccessor.Write(rs.Address.Pack(), data);
+
+            _counterCache.AddOrUpdate(rs.Address.Pack());
         }
 
         /// <summary>

Ryujinx.Graphics.Gpu/Engine/Methods.cs

@@ -52,6 +52,8 @@ namespace Ryujinx.Graphics.Gpu.Engine
 
             BufferManager  = new BufferManager(context);
             TextureManager = new TextureManager(context);
+
+            context.MemoryManager.MemoryUnmapped += _counterCache.MemoryUnmappedHandler;
         }
 
         /// <summary>