Throwing C ++ exceptions from a hardware exception handler. Why don't -fonon-call-exceptions behave as expected?

Question

Throwing C ++ exceptions from a hardware exception handler. Why don't -fonon-call-exceptions behave as expected?

I had this fun idea last night to catch the hardware exceptions and throw it away instead C++ exception. Thought it could be useful for things like FPU exceptionsthat usually either crash or silently return NaN, and then cause unexpected behavior. A C++ exceptionwould be much more desirable here.

So, I hacked all morning and finally got it to work. Almost. The compiler still does not understand that arithmetic operations can now be discarded C++ exceptionsand will silently discard a block around it try/catch. It works when an exception occurs in a function.

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;
    }
}

, ... ? gcc, ?

djgpp, ( ) DWARF .

edit: gcc flags -fnon-call-exceptions -fasynchronous-unwind-tables, , , . ...

edit: , gcc, , :

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

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

edit: try/catch , , .

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;
    }
}