Better check if the call can be replaced. Don't clone arguments.

ICSharpCode.Decompiler/IL/Transforms/ProxyCallReplacer.cs

@@ -52,84 +52,65 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 							transform.Run(function, context);
 						}
 					}
-					Call currentCall = new ProxyMethodVisitor().GetCalledMethod(function, context);
-					if (currentCall != null) {
-						Call newInst = (Call)currentCall.Clone();
 
-						// check if original arguments are only correct ldloc calls
-						for (int i = 0; i < currentCall.Arguments.Count; i++) {
-							var originalArg = currentCall.Arguments.ElementAtOrDefault(i);
-							if (originalArg.OpCode != OpCode.LdLoc ||
-								originalArg.Children.Count != 0 ||
-								((LdLoc)originalArg).Variable.Kind != VariableKind.Parameter ||
-								((LdLoc)originalArg).Variable.Index != i - 1) {
-								return;
-							}
-						}
-						newInst.Arguments.Clear();
-
-						ILInstruction thisArg = inst.Arguments.ElementAtOrDefault(0).Clone();
 
-						// special handling for first argument (this) - the underlying issue may be somewhere else
-						// normally
-						// leave IL_0000(await(callvirt<> n__0(ldobj xxHandler(ldloca this), ldobj System.Net.Http.HttpRequestMessage(ldloca request), ldobj System.Threading.CancellationToken(ldloca cancellationToken))))
-						// would be decompiled to
-						// return await((DelegatingHandler)this).SendAsync(request, cancellationToken);
-						// this changes it to
-						// return await base.SendAsync(request, cancellationToken);
-						if (thisArg.OpCode == OpCode.LdObj && thisArg.Children.Count > 0 && thisArg.Children[0].OpCode == OpCode.LdLoca) {
-							thisArg = new LdLoc(((LdLoca)thisArg.Children[0]).Variable);
+					if (function.Children.Count != 1)
+						return;
+					var blockContainer = function.Children[0];
+					if (blockContainer.OpCode != OpCode.BlockContainer)
+						return;
+					if (blockContainer.Children.Count != 1)
+						return;
+					var block = blockContainer.Children[0];
+					if (block.OpCode != OpCode.Block)
+						return;
+					if (block.Children.Count > 2)
+						return;
+					if (block.Children.Count == 2 && block.Children[1].OpCode != OpCode.Nop)
+						return;
+					var leave = block.Children[0];
+					if (leave.OpCode != OpCode.Leave)
+						return;
+					if (leave.Children.Count != 1)
+						return;
+					Call call = leave.Children[0] as Call;
+					if (call == null)
+						return;
+					// check if original arguments are only correct ldloc calls
+					for (int i = 0; i < call.Arguments.Count; i++) {
+						var originalArg = call.Arguments[i];
+						if (originalArg.OpCode != OpCode.LdLoc ||
+							originalArg.Children.Count != 0 ||
+							((LdLoc)originalArg).Variable.Kind != VariableKind.Parameter ||
+							((LdLoc)originalArg).Variable.Index != i - 1) {
+							return;
 						}
+					}
 
-						newInst.Arguments.Add(thisArg);
+					Call newInst = (Call)call.Clone();
 
-						// add everything except first argument
-						for (int i = 1; i < inst.Arguments.Count; i++) {
-							newInst.Arguments.Add(inst.Arguments.ElementAtOrDefault(i).Clone());
-						}
-						inst.ReplaceWith(newInst);
-					}
-				}
-			}
-		}
+					newInst.Arguments.Clear();
 
-		// Checks if the method is a proxy method by checking if it only contains a call instruction and if it has special compiler attributes.
-		private class ProxyMethodVisitor : ILVisitor
-		{
-			ILTransformContext context;
-			int invalidInstructions = 0;
-			Call currentCall;
+					ILInstruction thisArg = inst.Arguments[0];
 
-			public Call GetCalledMethod(ILFunction function, ILTransformContext context)
-			{
-				this.context = context;
-				function.AcceptVisitor(this);
-				if (invalidInstructions == 0) {
-					return currentCall;
-				}
-				return null;
-			}
+					// special handling for first argument (this) - the underlying issue may be somewhere else
+					// normally
+					// leave IL_0000(await(callvirt<> n__0(ldobj xxHandler(ldloca this), ldobj System.Net.Http.HttpRequestMessage(ldloca request), ldobj System.Threading.CancellationToken(ldloca cancellationToken))))
+					// would be decompiled to
+					// return await((DelegatingHandler)this).SendAsync(request, cancellationToken);
+					// this changes it to
+					// return await base.SendAsync(request, cancellationToken);
+					if (thisArg.OpCode == OpCode.LdObj && thisArg.Children.Count > 0 && thisArg.Children[0].OpCode == OpCode.LdLoca) {
+						thisArg = new LdLoc(((LdLoca)thisArg.Children[0]).Variable);
+					}
 
-			protected override void Default(ILInstruction inst)
-			{
-				if (inst.OpCode != OpCode.ILFunction &&
-					inst.OpCode != OpCode.BlockContainer &&
-					inst.OpCode != OpCode.Block &&
-					inst.OpCode != OpCode.Leave &&
-					inst.OpCode != OpCode.Nop) {
-					invalidInstructions++;
-				}
-				foreach (var child in inst.Children) {
-					child.AcceptVisitor(this);
-				}
-			}
+					newInst.Arguments.Add(thisArg);
 
-			protected internal override void VisitCall(Call inst)
-			{
-				if (currentCall == null) {
-					currentCall = inst;
-				} else {
-					invalidInstructions++; // more than one call in the function
+					// add everything except first argument
+					for (int i = 1; i < inst.Arguments.Count; i++) {
+						newInst.Arguments.Add(inst.Arguments[i]);
+					}
+					inst.ReplaceWith(newInst);
 				}
 			}
 		}