Re: C++ exceptions

On Tue, Jul 03, 2007 at 09:55:15PM +0100, Pedro Alves wrote:
> Perhaps.  Did you look closely?  I've registered the .pdata stuff and
> the data just before the function directly in the source file that
> uses it.  That means we can probably hide it in
> more-or-less-easy-to-use macros in any function we want.

I think future versions of gcc wont guarantee function placement
relative to top-level asm statements.

> It shouldn't.  It should not be on by default.  C++ exceptions are
> one thing.  SEH is another.  Unless they are properly integrated at
> the compiler level, they should only be mapped by the user.  Let's
> make it easy for the user to choose to use it instead.

Heh, I never thought of it that way.  I was working under the
assumption that mingw32ce was trying to be fully compatible with the
native CE compiler.  However, now that you mention it, raising a C++
exception due to an access violation seems like a pretty silly thing
to do.  (It helps in haret, because the only thing I use exceptions
for are access violations, but in a general application...)  I can
understand if you don't want this behavior.

> Think of it as func() being the __try {} block, and handler() being
> the __except block.  The user can use this to wrap seh into gcc's C++
> exceptions.  I certainly wouldn't want this in most of my c++ code.
> I hate when try {} catch (...) { } catches access violations.
> We can provide examples, and perhaps a lib for that to serve as example.
> 
> Kevin's case is special, since he is writing a tool that
> bypasses WinCE and accesses the physical memory and ARM registers
> directly.  How many here are doing that?

Yes, it is special.  I was reluctant to handle this locally in haret
because I viewed it as a general problem.  However, I'm starting to
think that raising a c++ exception isn't a particularly good solution
(despite what the msdn docs say).

I guess what I really want is to call setjmp before the offending code
and have a handler that will longjmp back to it if an access violation
comes up.  Doing this in a thread-safe manor is going to be a pain
though.

I'll try to take some of the sample code and integrate it into haret.

Thanks again,
-Kevin

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