Fix invalid IL code in Util.ElemOffset

disruptor-net · Mar 21, 2019 · e58c9f4 · e58c9f4
1 parent 64c8948
commit e58c9f4
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Showing 2 changed files with 40 additions and 8 deletions.
diff --git a/src/Disruptor.Tests/Utils/UtilTests.cs b/src/Disruptor.Tests/Utils/UtilTests.cs
@@ -1,3 +1,6 @@
+using System;
+using System.Linq;
+using Disruptor.Tests.Support;
 using NUnit.Framework;
 
 namespace Disruptor.Tests.Utils
@@ -36,5 +39,18 @@ public void ShouldReturnLongMaxWhenNoEventProcessors()
 
             Assert.AreEqual(long.MaxValue, Util.GetMinimumSequence(sequences));
         }
+
+        [Test]
+        public void ShouldReadArrayElement()
+        {
+            var array = Enumerable.Range(0, 100)
+                                  .Select(x => new LongEvent())
+                                  .ToArray();
+
+            for (var index = 0; index < array.Length; index++)
+            {
+                Assert.AreEqual(array[index], Util.Read<LongEvent>(array, index));
+            }
+        }
     }
-}
+}
diff --git a/src/Disruptor/Util/Util.cs b/src/Disruptor/Util/Util.cs
@@ -10,7 +10,7 @@ namespace Disruptor
     /// </summary>
     internal static class Util
     {
-        private static readonly int _offsetToArrayData = ElemOffset(new object[1]);
+        private static readonly int _offsetToArrayData = OffsetToArrayData();
 
         /// <summary>
         /// Calculate the next power of 2, greater than or equal to x.
@@ -42,6 +42,7 @@ public static int Log2(int i)
             {
                 ++r;
             }
+
             return r;
         }
 
@@ -68,6 +69,7 @@ public static long GetMinimumSequence(ISequence[] sequences, long minimum = long
                 var sequence = sequences[i].Value;
                 minimum = Math.Min(minimum, sequence);
             }
+
             return minimum;
         }
 
@@ -113,15 +115,29 @@ public static T Read<T>(object array, int index)
             return IL.Return<T>();
         }
 
-        private static int ElemOffset(object[] arr)
+        private static int OffsetToArrayData()
+        {
+            var array = new object[1];
+
+            return (int)ElemOffset(array, ref array[0]);
+        }
+
+        private static IntPtr ElemOffset(object origin, ref object target)
         {
-            Ldarg(nameof(arr));
-            Ldc_I4_0();
-            Ldelema(typeof(object));
-            Ldarg(nameof(arr));
+            IL.DeclareLocals(
+                false,
+                typeof(byte).MakeByRefType()
+            );
+
+            Ldarg(nameof(target));
+
+            Ldarg(nameof(origin)); // load the object
+            Stloc_0(); // convert the object pointer to a byref
+            Ldloc_0(); // load the object pointer as a byref
+
             Sub();
 
-            return IL.Return<int>();
+            return IL.Return<IntPtr>();
         }
     }
 }