Question

Why do embedded platform developers continuosly attempt to remove usage C++ exceptions from their SDKs?

For example, Bada SDK suggests the following workaround for the exception usage, which looks exceptionally ugly:

 result
 MyApp::InitTimer()
 {
    result r = E_SUCCESS;

    _pTimer = new Timer;

    r = _pTimer->Construct(*this);
    if (IsFailed(r))
    {
        goto CATCH;
    }

    _pTimer->Start(1000);
    if (IsFailed(r))
    {
        goto CATCH;
    }

    return r;
 CATCH:
     return r;
 }

What are the reasons for this behavior?

As far as I know, ARM compilers fully support C++ exceptions and this couldn’t actually be the matter. What else? Is the overhead of the exception usage and unwindings on ARM platforms really that BIG to spend a lot time making such workarounds?

Maybe something else I’m not aware of?

Thank you.

Answer 1

I can think of a couple of possible reasons:

• Older versions of the compiler didn’t support exceptions, so a lot of code has been written (and conventions have been established) where exceptions are not used
• Exceptions do have a cost, and it can be as much as 10-15% of your total execution time (they can also be implemented to take virtually no time, but use quite a bit of memory instead, which probably isn’t very desirable on embedded systems either)
• Embedded programmers tend to be a bit paranoid about code size, performance and, not least, code complexity. They often worry that “advanced” features may not work correctly with their compiler (and they’re often right too)