Graphics: decode oversized ASTC array textures slice-by-slice

Large 2D-array ASTC textures (e.g. from the TOTK 4K texture pack) can
decode to more than 2 GB of RGBA8, which overflows the Int32 size
computation in QueryDecompressedSize and crashes MemoryOwner.Rent.

Add QueryDecompressedSizeLong to detect the overflow and, in that case,
decode and upload the texture one layer/level slice at a time instead of
allocating a single oversized buffer.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Ryujinx.Graphics.Gpu/Image/Texture.cs

@@ -661,6 +661,32 @@ namespace Ryujinx.Graphics.Gpu.Image
                 }
             }
 
+            // Large 4K texture-pack array textures (e.g. a 2048x2048 ASTC 2D array with 121 layers) decode to
+            // more than 2 GiB of RGBA8, which overflows Int32 and cannot fit in a single array. Decode and
+            // upload them one slice at a time instead (each slice is only a few MiB), reusing the same
+            // single-slice path that partial synchronization already uses.
+            if (Info.FormatInfo.Format.IsAstc &&
+                !_context.Capabilities.SupportsAstcCompression &&
+                _depth == 1 &&
+                AstcDecoder.QueryDecompressedSizeLong(Info.Width, Info.Height, 1, Info.Levels, _layers) > int.MaxValue)
+            {
+                for (int layer = 0; layer < _layers; layer++)
+                {
+                    for (int level = 0; level < Info.Levels; level++)
+                    {
+                        int sliceOffset = _sizeInfo.AllOffsets[layer * Info.Levels + level];
+
+                        MemoryOwner<byte> sliceResult = ConvertToHostCompatibleFormat(data[sliceOffset..], level, single: true);
+
+                        HostTexture.SetData(sliceResult, layer, level);
+                    }
+                }
+
+                _hasData = true;
+
+                return;
+            }
+
             MemoryOwner<byte> result = ConvertToHostCompatibleFormat(data);
 
             if (ScaleFactor != 1f && AllowScaledSetData())

src/Ryujinx.Graphics.Texture/Astc/AstcDecoder.cs

@@ -115,6 +115,27 @@ namespace Ryujinx.Graphics.Texture.Astc
             return size * 4;
         }
 
+        /// <summary>
+        /// Computes the fully-decoded (RGBA8) size in bytes using 64-bit arithmetic, so callers can detect
+        /// when the result would overflow <see cref="int"/> (e.g. large 4K texture-pack array textures) and
+        /// decode slice-by-slice instead of allocating a single oversized buffer.
+        /// </summary>
+        public static long QueryDecompressedSizeLong(int sizeX, int sizeY, int sizeZ, int levelCount, int layerCount)
+        {
+            long size = 0;
+
+            for (int i = 0; i < levelCount; i++)
+            {
+                long levelSizeX = Math.Max(1, sizeX >> i);
+                long levelSizeY = Math.Max(1, sizeY >> i);
+                long levelSizeZ = Math.Max(1, sizeZ >> i);
+
+                size += levelSizeX * levelSizeY * levelSizeZ * layerCount;
+            }
+
+            return size * 4;
+        }
+
         public void ProcessBlock(int index)
         {
             Buffer16 inputBlock = MemoryMarshal.Cast<byte, Buffer16>(InputBuffer.Span)[index];