bytecode - 为什么这个修改后的程序集不运行？ (JIT 编译器遇到内部限制。)

Question

我修改了程序集的字节码以消除错误，现在当我尝试使用它时，我得到了一个 InvalidProgramException。我所做的就是用 NOPS 替换这段代码:

catch (Exception exception1)
{
    Exception exception = exception1;
    if (exception as InvalidValueException == null)
    {
        throw new InvalidGenerationException(2);
    }
    else
    {
        throw exception;
    }
}

IL 之前:

catch [mscorlib]System.Exception
{
    IL_022f: stloc.s exception
    IL_0231: ldloc.s exception
    IL_0233: isinst Custom.InvalidValueException
    IL_0238: brfalse.s IL_023d

    IL_023a: ldloc.s exception
    IL_023c: throw

    IL_023d: ldc.i4.1
    IL_023e: newobj instance void Custom.InvalidGenerationException ...
    IL_0243: throw
}

IL 之后:

catch [mscorlib]System.Exception
{
    IL_022f: nop
    IL_0230: nop
    IL_0231: nop
    IL_0232: nop
    IL_0233: nop
    IL_0234: nop
    IL_0235: nop
    IL_0236: nop
    IL_0237: nop
    IL_0238: nop
    IL_0239: nop
    IL_023a: nop
    IL_023b: nop
    IL_023c: nop
    IL_023d: nop
    IL_023e: nop
    IL_023f: nop
    IL_0240: nop
    IL_0241: nop
    IL_0242: nop
    IL_0243: nop
}

关于为什么这是错误的任何想法？

谢谢!

Answer 1

你原来的 catch block 总是会抛出。也就是说，没有办法“正常”退出该 block 。

您修改后的 catch block 不会抛出异常，因此您需要正常退出该 block 。您需要使用 leave或 leave.s这样做。

(您可能还需要 pop 将捕获的异常从堆栈中取出以保持整洁。不过我不确定这一点，您必须自己尝试一下。)

catch [mscorlib]System.Exception
{
    IL_022f: pop                // not certain if pop is necessary
    IL_0230: leave.s IL_0244
    IL_0232: nop
    IL_0233: nop
    IL_0234: nop
    IL_0235: nop
    IL_0236: nop
    IL_0237: nop
    IL_0238: nop
    IL_0239: nop
    IL_023a: nop
    IL_023b: nop
    IL_023c: nop
    IL_023d: nop
    IL_023e: nop
    IL_023f: nop
    IL_0240: nop
    IL_0241: nop
    IL_0242: nop
    IL_0243: nop
}
IL_0244: ret    // or whatever