Switch to using a struct instead of an ArrayPool

Author: arontsang

src/Peachpie.CodeAnalysis/Peachpie.CodeAnalysis.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <TargetFrameworks>net6.0</TargetFrameworks>
     <OutputType>exe</OutputType>
-    <NoWarn>$(NoWarn);1591</NoWarn>
+    <NoWarn>$(NoWarn);1591;RS1009</NoWarn>
     <AssemblyName>Peachpie.CodeAnalysis</AssemblyName>
     <PackageId>Peachpie.CodeAnalysis</PackageId>
     <PackageTags>php;peachpie;dotnet;compiler</PackageTags>

src/Peachpie.Runtime/PhpCallable.ArrayPool.tt

@@ -1,9 +1,10 @@
 <#@ output extension=".tt.cs" #>
+<#@ import namespace="System.Linq" #>
 using System;
-using System.Buffers;
-namespace Pchp.Core;
-using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+namespace Pchp.Core;
+
+
 
 partial interface IPhpCallable
 {
@@ -22,6 +23,8 @@ partial interface IPhpCallable
     for(int arity = 2; arity <= 16; arity++)
     {
 #>
+    
+
     /// <summary>
     /// Invokes the callback with given arguments.
     /// Uses ArrayPool to avoid allocation.
@@ -33,21 +36,26 @@ partial interface IPhpCallable
 <# } #>
         PhpValue p<#= arity - 1 #>)
     {
-        var phpArgs = ArrayPool<PhpValue>.Shared.Rent(<#= arity #>);
-        try
-        {
-<# for(int p = 0; p < arity; p++) { #>
-            phpArgs[<#= p #>] = p<#= p #>;
-<# } #>
-            return Invoke(ctx, new ReadOnlySpan<PhpValue>(phpArgs, 0, <#= arity #>));
-        }
-        finally
-        {
-            ArrayPool<PhpValue>.Shared.Return(phpArgs, true);
-        }
+        
+        var tuple = new PhpArgTuple<#= arity #>(<#= string.Join(", ", Enumerable.Range(0, arity).Select(index => $"p{index}")) #>);
+        var span = MemoryMarshal.CreateReadOnlySpan(ref tuple, 1);
+        var phpArgs = MemoryMarshal.Cast<PhpArgTuple<#= arity #>, PhpValue>(span);
+        return Invoke(ctx, phpArgs);
     }
 
 <#
     }
+
+for (int arity = 2; arity <= 16; arity++)
+{#>
+    [StructLayout(LayoutKind.Sequential)]
+    private record struct PhpArgTuple<#= arity #>(  
+<# for(int p = 0; p < arity - 1; p++) { #>
+        PhpValue Argument<#= p #>,
+<# } #>
+        PhpValue Argument<#= arity - 1 #>);
+
+<#        
+}
 #>
 }