CODEWITHSUNDEEP
c++windowsexceptionvisual-c++64-bit
Adar Arnon
Adar Arnon

Reputation: 303

C++ Exception "Skips" Try-Catch Clause in MSVC x64

I'm writing a program in C++. The program has been working fine for Win32 (x86), and recently I've tried compiling it natively for x64. Of course, stuff didn't work right away.

After debugging the problem, I've managed to reproduce it with this simple code snippet:

class MyException { };

int main()
{
    try {
        for (;;) {
            try {
                std::cout << "Throwing" << std::endl;

                throw MyException();

                if (1 == 0) {
                    continue;
                }
            } catch (const MyException&) {
                std::cout << "Catch 1" << std::endl;
            }
        }
    } catch (const MyException&) {
        std::cout << "Catch 2" << std::endl;
    }

    std::cout << "Done" << std::endl;

    return 0;
}

(I'll explain the if (1==0) clause soon)

When compiling this code using MSVC for x86 (I've used 2010), the result is as expected:

Throwing
Catch 1
Throwing
Catch 1
Throwing
Catch 1
Throwing
Catch 1
...

And so on, in an infinite loop.

However, compiling this code for x64 results in:

Throwing
Catch 2
Done

The exception completely skips the inner catch clause!

This only happens when the if (1 ==0) clause exists in my code. When I remove it, the exception is caught in "Catch 1" as expected.

I've tried using other compilers:

My question: is this an MSVC bug, or is this some undefined behavior in C++ I'm missing? If this indeed is an MSVC bug, I'd love to hear some insight on the cause.

Thanks.

Upvotes: 17

Views: 2216

Answers (3)

Nini75
Nini75

Reputation: 29

this is an old known issue, after digging it out this is what we found out some time ago.

http://social.msdn.microsoft.com/Forums/en-US/19eb8218-0dc4-4e4f-954f-4c4c3b3cd118/why-am-i-not-being-alerted-of-exceptions-from-methods-that-are-run-when-the-application-loads?forum=csharpide

Upvotes: 0

Spencer
Spencer

Reputation: 2214

This bug may have something to do with compiler optimization -- it's interesting that the linker crashes in your release build (when full optimization would theoretically be turned on).

Does your debug build have optimization completely disabled (/Od)?

Visual Studio Help also contains a statement (under "Optimization Best Practices") discouraging try/catch blocks in 64-bit code.

If you turn off optimization in the release build, the linker doesn't crash. It also won't crash (but will reproduce the bad behavior) if you remove just the "continue" statement. 

if (1==0) {
//continue;
}

Upvotes: 1

user2346536
user2346536

Reputation:

Try the switch /FAs switch:

http://msdn.microsoft.com/en-us/library/367y26c6%28v=vs.80%29.ASPX

somewhere in "additional output file" in your "compiler settings". ( make sure all other settings are the sames )

Then, do a diff between both outputs. post the diff here. I'm sure some people will be able to tell you the why and how, and maybe some compiler settings or code workaround.

Upvotes: 0

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