#899: decode jmp instruction into tail call

ICSharpCode.Decompiler.Tests/CorrectnessTestRunner.cs

@@ -162,6 +162,12 @@ namespace ICSharpCode.Decompiler.Tests
 			RunIL("BitNot.il", CompilerOptions.UseDebug | CompilerOptions.Force32Bit, AssemblerOptions.Force32Bit);
 		}
 
+		[Test]
+		public void Jmp()
+		{
+			RunIL("Jmp.il");
+		}
+
 		[Test]
 		public void UnsafeCode([ValueSource("defaultOptions")] CompilerOptions options)
 		{

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -44,6 +44,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <None Include="TestCases\Correctness\Jmp.il" />
     <None Include="TestCases\Correctness\BitNot.il" />
     <None Include="TestCases\Correctness\Readme.txt" />
   </ItemGroup>

ICSharpCode.Decompiler.Tests/TestCases/Correctness/Jmp.il

@@ -0,0 +1,47 @@
+.assembly extern mscorlib
+{
+	.publickeytoken = ( b7 7a 5c 56 19 34 e0 89 )
+	.ver 4:0:0:0
+}
+
+.assembly 'Jmp'
+{
+	.ver 0:0:0:0
+}
+
+.module Jmp.exe
+.corflags 0x00000001 // ILOnly
+
+.class private auto ansi abstract sealed beforefieldinit Program
+	extends [mscorlib]System.Object
+{
+	.method public hidebysig static void Main (string[] args) cil managed 
+	{
+		.maxstack 8
+		.entrypoint
+
+		ldstr "Method1(100) = {0}"
+		ldc.i4 100
+		call int32 Program::Method1(int32)
+		box int32
+		call void [mscorlib]System.Console::WriteLine(string, object)
+		ret
+	} // end of method Main
+	
+  .method public static int32 Method1(int32 val)
+	{
+    ldarg.0
+    ldc.i4.1
+    add
+    starg.s 0
+    jmp int32 Program::Method2(int32)
+  }
+	
+	.method public static int32 Method2(int32 val)
+	{
+		ldarg.0
+		ldc.i4.5
+		mul
+		ret
+	}
+}

ICSharpCode.Decompiler/IL/ILReader.cs

@@ -537,7 +537,7 @@ namespace ICSharpCode.Decompiler.IL
 				case Cil.Code.Initblk:
 					return new Initblk(size: Pop(StackType.I4), value: Pop(StackType.I4), address: PopPointer());
 				case Cil.Code.Jmp:
-					throw new NotImplementedException();
+					return DecodeJmp();
 				case Cil.Code.Ldarg:
 				case Cil.Code.Ldarg_S:
 					return Push(Ldarg(((ParameterDefinition)cecilInst.Operand).Sequence));
@@ -1251,6 +1251,22 @@ namespace ICSharpCode.Decompiler.IL
 			return Push(new BinaryNumericInstruction(@operator, left, right, checkForOverflow, sign));
 		}
 
+		ILInstruction DecodeJmp()
+		{
+			IMethod method = ReadAndDecodeMethodReference();
+			// Translate jmp into tail call:
+			Call call = new Call(method);
+			call.IsTail = true;
+			call.ILStackWasEmpty = true;
+			if (!method.IsStatic) {
+				call.Arguments.Add(Ldarg(0));
+			}
+			foreach (var p in method.Parameters) {
+				call.Arguments.Add(Ldarg(call.Arguments.Count));
+			}
+			return new Leave(mainContainer, call);
+		}
+
 		ILInstruction LdToken(IMetadataTokenProvider token)
 		{
 			if (token is TypeReference)