GPU: Track buffer migrations and flush source on incomplete copy (#3952)

* Track buffer migrations and flush source on incomplete copy

Makes sure that the modified range list is always from the latest iteration of the buffer, and flushes earlier iterations of a buffer if the data has not been migrated yet.

* Cleanup 1

* Reduce cost for redundant signal checks on Vulkan

* Only inherit the range list if there are pending ranges.

* Fix OpenGL

* Address Feedback

* Whoops

Ryujinx.Graphics.Gpu/Memory/BufferMigration.cs

@@ -0,0 +1,125 @@
+using System;
+
+namespace Ryujinx.Graphics.Gpu.Memory
+{
+    /// <summary>
+    /// A record of when buffer data was copied from one buffer to another, along with the SyncNumber when the migration will be complete.
+    /// Keeps the source buffer alive for data flushes until the migration is complete.
+    /// </summary>
+    internal class BufferMigration : IDisposable
+    {
+        /// <summary>
+        /// The offset for the migrated region.
+        /// </summary>
+        private readonly ulong _offset;
+
+        /// <summary>
+        /// The size for the migrated region.
+        /// </summary>
+        private readonly ulong _size;
+
+        /// <summary>
+        /// The buffer that was migrated from.
+        /// </summary>
+        private readonly Buffer _buffer;
+
+        /// <summary>
+        /// The source range action, to be called on overlap with an unreached sync number.
+        /// </summary>
+        private readonly Action<ulong, ulong> _sourceRangeAction;
+
+        /// <summary>
+        /// The source range list.
+        /// </summary>
+        private readonly BufferModifiedRangeList _source;
+
+        /// <summary>
+        /// The destination range list. This range list must be updated when flushing the source.
+        /// </summary>
+        public readonly BufferModifiedRangeList Destination;
+
+        /// <summary>
+        /// The sync number that needs to be reached for this migration to be removed. This is set to the pending sync number on creation.
+        /// </summary>
+        public readonly ulong SyncNumber;
+
+        /// <summary>
+        /// Creates a record for a buffer migration.
+        /// </summary>
+        /// <param name="buffer">The source buffer for this migration</param>
+        /// <param name="sourceRangeAction">The flush action for the source buffer</param>
+        /// <param name="source">The modified range list for the source buffer</param>
+        /// <param name="dest">The modified range list for the destination buffer</param>
+        /// <param name="syncNumber">The sync number for when the migration is complete</param>
+        public BufferMigration(
+            Buffer buffer,
+            Action<ulong, ulong> sourceRangeAction,
+            BufferModifiedRangeList source,
+            BufferModifiedRangeList dest,
+            ulong syncNumber)
+        {
+            _offset = buffer.Address;
+            _size = buffer.Size;
+            _buffer = buffer;
+            _sourceRangeAction = sourceRangeAction;
+            _source = source;
+            Destination = dest;
+            SyncNumber = syncNumber;
+        }
+
+        /// <summary>
+        /// Determine if the given range overlaps this migration, and has not been completed yet.
+        /// </summary>
+        /// <param name="offset">Start offset</param>
+        /// <param name="size">Range size</param>
+        /// <param name="syncNumber">The sync number that was waited on</param>
+        /// <returns>True if overlapping and in progress, false otherwise</returns>
+        public bool Overlaps(ulong offset, ulong size, ulong syncNumber)
+        {
+            ulong end = offset + size;
+            ulong destEnd = _offset + _size;
+            long syncDiff = (long)(syncNumber - SyncNumber); // syncNumber is less if the copy has not completed.
+
+            return !(end <= _offset || offset >= destEnd) && syncDiff < 0;
+        }
+
+        /// <summary>
+        /// Determine if the given range matches this migration.
+        /// </summary>
+        /// <param name="offset">Start offset</param>
+        /// <param name="size">Range size</param>
+        /// <returns>True if the range exactly matches, false otherwise</returns>
+        public bool FullyMatches(ulong offset, ulong size)
+        {
+            return _offset == offset && _size == size;
+        }
+
+        /// <summary>
+        /// Perform the migration source's range action on the range provided, clamped to the bounds of the source buffer.
+        /// </summary>
+        /// <param name="offset">Start offset</param>
+        /// <param name="size">Range size</param>
+        /// <param name="syncNumber">Current sync number</param>
+        /// <param name="parent">The modified range list that originally owned this range</param>
+        public void RangeActionWithMigration(ulong offset, ulong size, ulong syncNumber, BufferModifiedRangeList parent)
+        {
+            ulong end = offset + size;
+            end = Math.Min(_offset + _size, end);
+            offset = Math.Max(_offset, offset);
+
+            size = end - offset;
+
+            _source.RangeActionWithMigration(offset, size, syncNumber, parent, _sourceRangeAction);
+        }
+
+        /// <summary>
+        /// Removes this reference to the range list, potentially allowing for the source buffer to be disposed.
+        /// </summary>
+        public void Dispose()
+        {
+            Destination.RemoveMigration(this);
+
+            _buffer.DecrementReferenceCount();
+        }
+    }
+}