Merge pull request #719 from Sergio0694/dev/opportunistic-stackalloc

Use stackalloc to marshal constant buffer if possible
Sergio0694 · Dec 15, 2023 · 347ae52 · 347ae52
2 parents 8c1a547 + eab0bfb
commit 347ae52
Show file tree

Hide file tree

Showing 2 changed files with 19 additions and 4 deletions.
diff --git a/src/ComputeSharp.D2D1.WinUI/Extensions/ID2D1EffectExtensions.cs b/src/ComputeSharp.D2D1.WinUI/Extensions/ID2D1EffectExtensions.cs
@@ -35,7 +35,11 @@ public static T GetConstantBuffer<T>(this ref ID2D1Effect d2D1Effect)
             return default;
         }
 
-        byte[] buffer = ArrayPool<byte>.Shared.Rent(constantBufferSize);
+        byte[]? bufferArray = null;
+
+        Span<byte> buffer = constantBufferSize <= 64
+            ? stackalloc byte[64]
+            : bufferArray = ArrayPool<byte>.Shared.Rent(constantBufferSize);
 
         fixed (byte* p = buffer)
         {
@@ -49,7 +53,10 @@ public static T GetConstantBuffer<T>(this ref ID2D1Effect d2D1Effect)
 
         T shader = T.CreateFromConstantBuffer(buffer);
 
-        ArrayPool<byte>.Shared.Return(buffer);
+        if (bufferArray is not null)
+        {
+            ArrayPool<byte>.Shared.Return(bufferArray);
+        }
 
         return shader;
     }

diff --git a/src/ComputeSharp.D2D1/Shaders/Interop/D2D1DrawInfoUpdateContext{T}.cs b/src/ComputeSharp.D2D1/Shaders/Interop/D2D1DrawInfoUpdateContext{T}.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Buffers;
 using ComputeSharp.D2D1.Descriptors;
 using ComputeSharp.D2D1.Extensions;
@@ -37,7 +38,11 @@ public T GetConstantBuffer()
 
         this.d2D1DrawInfoUpdateContext->GetConstantBufferSize(&constantBufferSize).Assert();
 
-        byte[] buffer = ArrayPool<byte>.Shared.Rent((int)constantBufferSize);
+        byte[]? bufferArray = null;
+
+        Span<byte> buffer = constantBufferSize <= 64
+            ? stackalloc byte[64]
+            : bufferArray = ArrayPool<byte>.Shared.Rent((int)constantBufferSize);
 
         fixed (byte* pBuffer = buffer)
         {
@@ -46,7 +51,10 @@ public T GetConstantBuffer()
 
         T shader = T.CreateFromConstantBuffer(buffer);
 
-        ArrayPool<byte>.Shared.Return(buffer);
+        if (bufferArray is not null)
+        {
+            ArrayPool<byte>.Shared.Return(bufferArray);
+        }
 
         return shader;
     }