Merge pull request #203 from nike4613/dont-chage-opcodes

Relink variable definitions when cloning DMD bodies
MonoMod · Dec 12, 2024 · c52e274 · c52e274
2 parents 80b16bf + ac6c21c
commit c52e274
Showing 2 changed files with 35 additions and 12 deletions.
diff --git a/src/MonoMod.UnitTest/DynamicMethodDefinitionTest.cs b/src/MonoMod.UnitTest/DynamicMethodDefinitionTest.cs
@@ -266,5 +266,24 @@ public void DMDGenerateDoesNotModifyDMD()
             Assert.Equal(OpCodes.Br_S, genClone.Definition.Body.Instructions[0].OpCode);
         }
 
+        [Fact]
+        public void ClonedDMDRelinksVariableDefinitions()
+        {
+            using var origDmd = new DynamicMethodDefinition("Test DMD", null, []);
+            var il = origDmd.GetILProcessor();
+            var varDef = new VariableDefinition(il.Import(typeof(string)));
+            il.Body.Variables.Add(varDef);
+            il.Emit(OpCodes.Ldstr, "hello");
+            il.Emit(OpCodes.Stloc, varDef);
+            il.Emit(OpCodes.Ldloc, varDef);
+            il.Emit(OpCodes.Ret);
+
+            using var genClone = new DynamicMethodDefinition(origDmd);
+
+            Assert.NotEqual(varDef, genClone.Definition.Body.Variables[0]);
+            var newVarDef = genClone.Definition.Body.Variables[0];
+            Assert.Equal(newVarDef, genClone.Definition.Body.Instructions[1].Operand);
+            Assert.Equal(newVarDef, genClone.Definition.Body.Instructions[2].Operand);
+        }
     }
 }
diff --git a/src/MonoMod.Utils/Extensions.Relinker.cs b/src/MonoMod.Utils/Extensions.Relinker.cs
@@ -102,18 +102,6 @@ public static partial class Extensions
                 return c;
             }));
 
-            foreach (var c in bc.Instructions)
-            {
-                if (c.Operand is Instruction target)
-                {
-                    c.Operand = bc.Instructions[bo.Instructions.IndexOf(target)];
-                }
-                else if (c.Operand is Instruction[] targets)
-                {
-                    c.Operand = targets.Select(i => bc.Instructions[bo.Instructions.IndexOf(i)]).ToArray();
-                }
-            }
-
             bc.ExceptionHandlers.AddRange(bo.ExceptionHandlers.Select(o =>
             {
                 var c = new ExceptionHandler(o.HandlerType);
@@ -173,6 +161,22 @@ Instruction ResolveInstrOff(int off)
                 return c;
             }));
 
+            foreach (var c in bc.Instructions)
+            {
+                if (c.Operand is Instruction target)
+                {
+                    c.Operand = bc.Instructions[bo.Instructions.IndexOf(target)];
+                }
+                else if (c.Operand is Instruction[] targets)
+                {
+                    c.Operand = targets.Select(i => bc.Instructions[bo.Instructions.IndexOf(i)]).ToArray();
+                }
+                else if (c.Operand is VariableDefinition vardef)
+                {
+                    c.Operand = bc.Variables[vardef.Index];
+                }
+            }
+
             return bc;
         }