Only use persistent buffers to flush on NVIDIA and Windows+AMD (#2489)

It seems like this method of flushing data is much slower on Mesa drivers, and slightly slower on Intel Windows. Have not tested Intel Mesa, but I'm assuming it is the same as AMD.

This also adds vendor detection for AMD on Unix, which counted as "Unknown" before.

Ryujinx.Graphics.OpenGL/HwCapabilities.cs

@@ -20,7 +20,8 @@ namespace Ryujinx.Graphics.OpenGL
         public enum GpuVendor
         {
             Unknown,
-            Amd,
+            AmdWindows,
+            AmdUnix,
             IntelWindows,
             IntelUnix,
             Nvidia
@@ -28,10 +29,15 @@ namespace Ryujinx.Graphics.OpenGL
 
         private static readonly Lazy<GpuVendor> _gpuVendor = new Lazy<GpuVendor>(GetGpuVendor);
 
+        private static bool _isAMD   => _gpuVendor.Value == GpuVendor.AmdWindows || _gpuVendor.Value == GpuVendor.AmdUnix;
+        private static bool _isIntel => _gpuVendor.Value == GpuVendor.IntelWindows || _gpuVendor.Value == GpuVendor.IntelUnix;
+
         public static GpuVendor Vendor => _gpuVendor.Value;
 
         private static Lazy<float> _maxSupportedAnisotropy = new Lazy<float>(GL.GetFloat((GetPName)All.MaxTextureMaxAnisotropy));
 
+        public static bool UsePersistentBufferForFlush       => _gpuVendor.Value == GpuVendor.AmdWindows || _gpuVendor.Value == GpuVendor.Nvidia;
+
         public static bool SupportsAstcCompression           => _supportsAstcCompression.Value;
         public static bool SupportsImageLoadFormatted        => _supportsImageLoadFormatted.Value;
         public static bool SupportsParallelShaderCompile     => _supportsParallelShaderCompile.Value;
@@ -41,9 +47,9 @@ namespace Ryujinx.Graphics.OpenGL
         public static bool SupportsTextureShadowLod          => _supportsTextureShadowLod.Value;
         public static bool SupportsViewportSwizzle           => _supportsViewportSwizzle.Value;
 
-        public static bool SupportsMismatchingViewFormat    => _gpuVendor.Value != GpuVendor.Amd && _gpuVendor.Value != GpuVendor.IntelWindows;
+        public static bool SupportsMismatchingViewFormat    => _gpuVendor.Value != GpuVendor.AmdWindows && _gpuVendor.Value != GpuVendor.IntelWindows;
         public static bool SupportsNonConstantTextureOffset => _gpuVendor.Value == GpuVendor.Nvidia;
-        public static bool RequiresSyncFlush                => _gpuVendor.Value == GpuVendor.Amd || _gpuVendor.Value == GpuVendor.IntelWindows || _gpuVendor.Value == GpuVendor.IntelUnix;
+        public static bool RequiresSyncFlush                => _gpuVendor.Value == GpuVendor.AmdWindows || _isIntel;
 
         public static int MaximumComputeSharedMemorySize => _maximumComputeSharedMemorySize.Value;
         public static int StorageBufferOffsetAlignment   => _storageBufferOffsetAlignment.Value;
@@ -86,7 +92,11 @@ namespace Ryujinx.Graphics.OpenGL
             }
             else if (vendor == "ati technologies inc." || vendor == "advanced micro devices, inc.")
             {
-                return GpuVendor.Amd;
+                return GpuVendor.AmdWindows;
+            }
+            else if (vendor == "amd" || vendor == "x.org")
+            {
+                return GpuVendor.AmdUnix;
             }
             else
             {

Ryujinx.Graphics.OpenGL/Image/TextureView.cs

@@ -121,7 +121,31 @@ namespace Ryujinx.Graphics.OpenGL.Image
 
         public byte[] GetData()
         {
-            return _renderer.PersistentBuffers.Default.GetTextureData(this);
+            int size = 0;
+
+            for (int level = 0; level < Info.Levels; level++)
+            {
+                size += Info.GetMipSize(level);
+            }
+
+            if (HwCapabilities.UsePersistentBufferForFlush)
+            {
+                return _renderer.PersistentBuffers.Default.GetTextureData(this, size);
+            }
+            else
+            {
+                byte[] data = new byte[size];
+
+                unsafe
+                {
+                    fixed (byte* ptr = data)
+                    {
+                        WriteTo((IntPtr)ptr);
+                    }
+                }
+
+                return data;
+            }
         }
 
         public void WriteToPbo(int offset, bool forceBgra)

Ryujinx.Graphics.OpenGL/PersistentBuffers.cs

@@ -63,15 +63,8 @@ namespace Ryujinx.Graphics.OpenGL
             GL.DeleteSync(sync);
         }
 
-        public byte[] GetTextureData(TextureView view)
+        public byte[] GetTextureData(TextureView view, int size)
         {
-            int size = 0;
-
-            for (int level = 0; level < view.Info.Levels; level++)
-            {
-                size += view.Info.GetMipSize(level);
-            }
-
             EnsureBuffer(size);
 
             GL.BindBuffer(BufferTarget.PixelPackBuffer, _copyBufferHandle);

Ryujinx.Graphics.OpenGL/Renderer.cs

@@ -93,7 +93,14 @@ namespace Ryujinx.Graphics.OpenGL
 
         public byte[] GetBufferData(BufferHandle buffer, int offset, int size)
         {
-            return PersistentBuffers.Default.GetBufferData(buffer, offset, size);
+            if (HwCapabilities.UsePersistentBufferForFlush)
+            {
+                return PersistentBuffers.Default.GetBufferData(buffer, offset, size);
+            }
+            else
+            {
+                return Buffer.GetData(buffer, offset, size);
+            }
         }
 
         public Capabilities GetCapabilities()