从硬件异常处理程序中抛出C异常.为什么-fnon-call-exceptions的

所以我整个上午一直在黑客攻击,最后让它上班.好吧,差不多.编译器仍然没有意识到算术运算现在可以抛出C异常,并且会静默地丢弃它周围的try / catch块.它在函数中发生异常时起作用.

void throw_exception()
{ 
    throw std::runtime_error("Division by zero!");
}

__attribute__((noinline))
void try_div0()
{
    cout << 1 / 0 << endl;
}

int main()
{
    // this class traps a hardware exception (division by zero,in this case) and calls the supplied lambda function.
    // uh,no,you probably don't want to see the assembly code behind this...
    exception_wrapper div0_exc { 0,[] (exception_frame* frame,bool)
    { 
        if (frame->address.segment != get_cs()) return false;           // only handle exceptions that occured in our own code
        frame->stack.offset -= 4;                                       // sub <fault esp>,4;
        auto* stack = reinterpret_cast<std::uintptr_t *>(frame->stack.offset); // get <fault esp>
        *stack = frame->address.offset;                                 // mov [<fault esp>],<fault address>;
        frame->address.offset = reinterpret_cast<std::uintptr_t>(throw_exception);  // set return address to throw_exception()
        return true;    // exception handled!
    } };

    try
    {
        // cout << 1 / 0 << endl;   // this throws,as expected,but calls std::terminate().
        try_div0();                 // this exception is caught.
    }
    catch (std::exception& e)
    {
        cout << "oops: " << e.what() << endl;
    }
}

我意识到这是一个不寻常的问题……但是我有什么方法可以让这项工作成功吗？告诉gcc可以在任何地方发生异常的方法吗？

我正在使用djgpp编译(我相信)它使用DWARF异常处理.

编辑：我刚刚找到了gcc标志-fnon-call-exceptions和-fasynchronous-unwind-tables,这似乎是我正在寻找的.但它仍然无效……

编辑：现在使用前面提到的gcc标志,当两个函数调用之间发生异常时,它会捕获：

inline void nop() { asm(""); } 
    // or { cout << flush; } or something. empty function does not work.

int main()
{
    /* ... */
    try
    {
        nop();
        cout << 1 / 0 << endl;
        nop();
    }
    /* ... */
}

编辑：嵌套的try / catch块具有相同的效果,除非捕获的指令前面有函数调用,否则不会捕获异常.

inline void nop() { asm(""); }

void try_div(int i)
{
    try
    {
        // this works,catches exception in try_div(0).
        nop();
        cout << 1 / i << endl;
        try_div(i - 1);

        // without the first nop(),calls std::terminate()
        //cout << 1 / i << endl;
        //try_div(i - 1);

        // reverse order,also terminates.
        //if (i != 0) try_div(i - 1);
        //cout << 1 / i << endl;
        //nop();
    }
    catch (std::exception& e)
    {
        cout << "caught in try_div(" << i << "): " << e.what() << endl;
    }
}

int main()
{
    /* ... */

    try
    {
        try_div(4);
    }
    catch (std::exception& e)
    {
        cout << "caught in main(): " << e.what() << endl;
    }
}

编辑：我已将此作为可能的bug in gcc提交,并将我的代码缩减为简单的test case.