Optimize Texture Binding and Shader Specialization Checks (#3399)

* Changes 1

* Changes 2

* Better ModifiedSequence handling

This should handle PreciseEvents properly, and simplifies a few things.

* Minor changes, remove debug log

* Handle stage.Info being null

Hopefully fixes Catherine crash

* Fix shader specialization fast texture lookup

* Fix some things.

* Address Feedback Part 1

* Make method static.

Ryujinx.Graphics.Shader/TextureHandle.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Runtime.CompilerServices;
 
 namespace Ryujinx.Graphics.Shader
@@ -50,5 +51,63 @@ namespace Ryujinx.Graphics.Shader
         {
             return (handle & 0x3fff, (handle >> 14) & 0x3fff, (TextureHandleType)((uint)handle >> 28));
         }
+
+        /// <summary>
+        /// Unpacks the texture ID from the real texture handle.
+        /// </summary>
+        /// <param name="packedId">The real texture handle</param>
+        /// <returns>The texture ID</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int UnpackTextureId(int packedId)
+        {
+            return (packedId >> 0) & 0xfffff;
+        }
+
+        /// <summary>
+        /// Unpacks the sampler ID from the real texture handle.
+        /// </summary>
+        /// <param name="packedId">The real texture handle</param>
+        /// <returns>The sampler ID</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int UnpackSamplerId(int packedId)
+        {
+            return (packedId >> 20) & 0xfff;
+        }
+
+        /// <summary>
+        /// Reads a packed texture and sampler ID (basically, the real texture handle)
+        /// from a given texture/sampler constant buffer.
+        /// </summary>
+        /// <param name="wordOffset">A word offset of the handle on the buffer (the "fake" shader handle)</param>
+        /// <param name="cachedTextureBuffer">The constant buffer to fetch texture IDs from</param>
+        /// <param name="cachedSamplerBuffer">The constant buffer to fetch sampler IDs from</param>
+        /// <returns>The packed texture and sampler ID (the real texture handle)</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static int ReadPackedId(int wordOffset, ReadOnlySpan<int> cachedTextureBuffer, ReadOnlySpan<int> cachedSamplerBuffer)
+        {
+            (int textureWordOffset, int samplerWordOffset, TextureHandleType handleType) = UnpackOffsets(wordOffset);
+
+            int handle = cachedTextureBuffer[textureWordOffset];
+
+            // The "wordOffset" (which is really the immediate value used on texture instructions on the shader)
+            // is a 13-bit value. However, in order to also support separate samplers and textures (which uses
+            // bindless textures on the shader), we extend it with another value on the higher 16 bits with
+            // another offset for the sampler.
+            // The shader translator has code to detect separate texture and sampler uses with a bindless texture,
+            // turn that into a regular texture access and produce those special handles with values on the higher 16 bits.
+            if (handleType != TextureHandleType.CombinedSampler)
+            {
+                int samplerHandle = cachedSamplerBuffer[samplerWordOffset];
+
+                if (handleType == TextureHandleType.SeparateSamplerId)
+                {
+                    samplerHandle <<= 20;
+                }
+
+                handle |= samplerHandle;
+            }
+
+            return handle;
+        }
     }
 }