Merge pull request #24 from nedavni/Fix_NullRef_LdElem

Fixed NullReferenceException in scenario with branches & Ldelem
skbkontur · Dec 25, 2020 · d6bdb9d · d6bdb9d
2 parents f666e8f + ba23b76
commit d6bdb9d
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Showing 2 changed files with 72 additions and 1 deletion.
diff --git a/GrEmit.Tests/Test.cs b/GrEmit.Tests/Test.cs
@@ -3,6 +3,7 @@
 using System.Reflection;
 using System.Reflection.Emit;
 using System.Runtime.InteropServices;
+using System.Text;
 
 using GrEmit.Utils;
 
@@ -18,6 +19,76 @@ namespace GrEmit.Tests
     [TestFixture]
     public class Test
     {
+        [Test]
+        public void Test_LdElem_OnClass_ShouldEmitType()
+        {
+            // private static string ClearAll(StringBuilder[] input)
+            // {
+            //     string result = string.Empty;
+            //     
+            //     for (int i = 0; i < input.Length; ++i)
+            //     {
+            //         result = string.Concat(result, input[i]);
+            //     }
+            //     return result;
+            // }
+
+            var method = new DynamicMethod(nameof(Test_LdElem_OnClass_ShouldEmitType), typeof(string), new[] {typeof(StringBuilder[])}, typeof(Test));
+            using (var il = new GroboIL(method))
+            {
+                var index = il.DeclareLocal(typeof(int));
+                var result = il.DeclareLocal(typeof(string));
+
+                il.Ldc_I4(0);
+                il.Stloc(index);
+
+                il.Ldstr(string.Empty);
+                il.Stloc(result);
+
+                var start = il.DefineLabel("start");
+                var compare = il.DefineLabel("compare");
+
+                il.Br(compare);
+                il.MarkLabel(start);
+
+                il.Ldloc(result);
+
+                il.Ldarg(0);
+                il.Ldloc(index);
+                il.Ldelem(typeof(StringBuilder));
+                il.Call(typeof(object).GetMethod(nameof(ToString)));
+
+                il.Call(typeof(string).GetMethod(nameof(string.Concat), new[] {typeof(string), typeof(string)}));
+                il.Stloc(result);
+
+                il.Ldloc(index);
+                il.Ldc_I4(1);
+                il.Add();
+                il.Stloc(index);
+
+                il.MarkLabel(compare);
+                il.Ldloc(index);
+                il.Ldarg(0);
+                il.Ldlen();
+                il.Conv<int>();
+                il.Blt(start, false);
+
+                il.Ldloc(result);
+                il.Ret();
+            }
+
+            var check = "12345";
+
+            var inputs = new StringBuilder[check.Length];
+            for (var i = 0; i < check.Length; i++)
+            {
+                inputs[i] = new StringBuilder(check[i].ToString());
+            }
+
+            var func = (Func<StringBuilder[], string>)method.CreateDelegate(typeof(Func<StringBuilder[], string>));
+            Assert.That(func(inputs), Is.EqualTo(check));
+        }
+
         [Test]
         public void TestLocalloc()
         {

diff --git a/GrEmit/GroboIL.cs b/GrEmit/GroboIL.cs
@@ -2131,7 +2131,7 @@ private ILInstructionComment GetComment()
 
         private void Emit(OpCode opCode, TypeILInstructionParameter parameter)
         {
-            var lineNumber = ilCode.Append(opCode, new EmptyILInstructionComment());
+            var lineNumber = ilCode.Append(opCode, parameter, new EmptyILInstructionComment());
             if (analyzeStack && stack != null)
                 MutateStack(opCode, parameter);
             ilCode.SetComment(lineNumber, GetComment());