Implement lazy flush-on-read for Buffers (SSBO/Copy) (#1790)

* Initial implementation of buffer flush (VERY WIP)

* Host shaders need to be rebuilt for the SSBO write flag.

* New approach with reserved regions and gl sync

* Fix a ton of buffer issues.

* Remove unused buffer unmapped behaviour

* Revert "Remove unused buffer unmapped behaviour"

This reverts commit f1700e52fb8760180ac5e0987a07d409d1e70ece.

* Delete modified ranges on unmap

Fixes potential crashes in Super Smash Bros, where a previously modified range could lie on either side of an unmap.

* Cache some more delegates.

* Dispose Sync on Close

* Also create host sync for GPFifo syncpoint increment.

* Copy buffer optimization, add docs

* Fix race condition with OpenGL Sync

* Enable read tracking on CommandBuffer, insert syncpoint on WaitForIdle

* Performance: Only flush individual pages of SSBO at a time

This avoids flushing large amounts of data when only a small amount is actually used.

* Signal Modified rather than flushing after clear

* Fix some docs and code style.

* Introduce a new test for tracking memory protection.

Sucessfully demonstrates that the bug causing write protection to be cleared by a read action has been fixed. (these tests fail on master)

* Address Comments

* Add host sync for SetReference

This ensures that any indirect draws will correctly flush any related buffer data written before them. Fixes some flashing and misplaced world geometry in MH rise.

* Make PageAlign static

* Re-enable read tracking, for reads.

Ryujinx.Graphics.Gpu/GpuContext.cs

@@ -4,6 +4,7 @@ using Ryujinx.Graphics.Gpu.Engine.GPFifo;
 using Ryujinx.Graphics.Gpu.Memory;
 using Ryujinx.Graphics.Gpu.Synchronization;
 using System;
+using System.Collections.Generic;
 using System.Threading;
 
 namespace Ryujinx.Graphics.Gpu
@@ -59,6 +60,18 @@ namespace Ryujinx.Graphics.Gpu
         /// </summary>
         internal int SequenceNumber { get; private set; }
 
+        /// <summary>
+        /// Internal sync number, used to denote points at which host synchronization can be requested.
+        /// </summary>
+        internal ulong SyncNumber { get; private set; }
+
+        /// <summary>
+        /// Actions to be performed when a CPU waiting sync point is triggered.
+        /// If there are more than 0 items when this happens, a host sync object will be generated for the given <see cref="SyncNumber"/>,
+        /// and the SyncNumber will be incremented.
+        /// </summary>
+        internal List<Action> SyncActions { get; }
+
         private readonly Lazy<Capabilities> _caps;
 
         /// <summary>
@@ -87,6 +100,8 @@ namespace Ryujinx.Graphics.Gpu
             _caps = new Lazy<Capabilities>(Renderer.GetCapabilities);
 
             HostInitalized = new ManualResetEvent(false);
+
+            SyncActions = new List<Action>();
         }
 
         /// <summary>
@@ -118,6 +133,37 @@ namespace Ryujinx.Graphics.Gpu
             PhysicalMemory = new PhysicalMemory(cpuMemory);
         }
 
+        /// <summary>
+        /// Registers an action to be performed the next time a syncpoint is incremented.
+        /// This will also ensure a host sync object is created, and <see cref="SyncNumber"/> is incremented.
+        /// </summary>
+        /// <param name="action">The action to be performed on sync object creation</param>
+        public void RegisterSyncAction(Action action)
+        {
+            SyncActions.Add(action);
+        }
+
+        /// <summary>
+        /// Creates a host sync object if there are any pending sync actions. The actions will then be called.
+        /// If no actions are present, a host sync object is not created.
+        /// </summary>
+        public void CreateHostSyncIfNeeded()
+        {
+            if (SyncActions.Count > 0)
+            {
+                Renderer.CreateSync(SyncNumber);
+
+                SyncNumber++;
+
+                foreach (Action action in SyncActions)
+                {
+                    action();
+                }
+
+                SyncActions.Clear();
+            }
+        }
+
         /// <summary>
         /// Disposes all GPU resources currently cached.
         /// It's an error to push any GPU commands after disposal.