Fix net472 float bit conversion compatibility

Agent-Logs-Url: https://github.com/dadhi/FastExpressionCompiler/sessions/72f15b2a-4d12-499c-a213-bcad43d6e4be

Co-authored-by: dadhi <39516+dadhi@users.noreply.github.com>

Author: Copilot

src/FastExpressionCompiler.LightExpression/FlatExpression.cs

@@ -1312,7 +1312,7 @@ private static bool TryGetInlineConstantValue32(object value, Type type, out int
                 value32 = unchecked((int)(uint)value);
                 return true;
             case TypeCode.Single:
-                value32 = BitConverter.SingleToInt32Bits((float)value);
+                value32 = ConvertSingleToInt32Bits((float)value);
                 return true;
             default:
                 value32 = default;
@@ -1342,11 +1342,29 @@ private static object ReadInlineConstantValue32(Type type, int value32)
             TypeCode.UInt16 => (ushort)value32,
             TypeCode.Int32 => value32,
             TypeCode.UInt32 => unchecked((uint)value32),
-            TypeCode.Single => BitConverter.Int32BitsToSingle(value32),
+            TypeCode.Single => ConvertInt32BitsToSingle(value32),
             _ => Throw.UnsupportedInlineConstantType<object>(type)
         };
     }
 
+    [StructLayout(LayoutKind.Explicit)]
+    private struct SingleInt32Union
+    {
+        [FieldOffset(0)]
+        public float Single;
+
+        [FieldOffset(0)]
+        public int Int32;
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static int ConvertSingleToInt32Bits(float value) =>
+        new SingleInt32Union { Single = value }.Int32;
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static float ConvertInt32BitsToSingle(int value) =>
+        new SingleInt32Union { Int32 = value }.Single;
+
     private ChildList GetChildren(int index)
     {
         ref var node = ref Nodes.GetSurePresentRef(index);