Danny Backx wrote: > On Tue, 2007-07-03 at 03:14 +0100, Pedro Alves wrote: >>> Let me see if I can come up with something in the following days. >> OK, here is my take. See/try attached. >> >> - It shows that it is possible to have SEH/ARM with a few >> macros (to hide the __asm__). >> - It shows that is is possible to wrap SEH in c++ exceptions. >> - It shows that is can be pretty much cleaned up. :) >> - It shows that there is no need to change the entry point. > > As I wrote the other day, I have something similar in the works. My > version looks a lot like yours because basically you did now what I did > last week :-) >
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 also have my version properly integrated in src/mingw so my local > version of arm-wince-mingw32ce-gcc picks this up automatically. That > wasn't hard. > If you get macros going on, then we can wrap the default WinMain with the equivalent of __try/__except. I don't like the changing the entry point into asm copied directly from cegcc. Among other problems, it only works in the main thread. Any other thread will still blow up on an exception happening. > Haven't done that for C++ yet because Kevin's message prompted me to > reveal what I was playing with. I am in the process of figuring out > which C++ constructs this should use, and (depending on that) how the > hook from C++ into the mingw startup should work. > 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. Please stuff like this: http://blogs.msdn.com/david_leblanc/archive/2007/04/03/exception-handlers-are-baaad.aspx (Particularly funny that the first post comes from a CE team guy). Another point of view, is that there isn't any standard class to throw in the presence of a SEH exception. We shouldn't force any particular class we invent on the users. We should provide the tools to have them build the class hierarchy they want. There are examples of that all over the web (google: seh c++ exceptions). #define SEH_FUNC_START(...) ... #define SEH_FUNC_END(...) ... #define SEH_FUNC_REGISTER(...) ... handler() { users handler here. } int func (); SEH_FUNC_REGISTER (func, handler); int func () { SEH_FUNC_START (func); < really prologue end. ... SEH_FUNC_END (func); } 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? > Opinions on how to do this in C++ are welcome, my C++ is still rusty :-) > > Pedro appears to have spent more time in the assembler code than I did. > (Thanks, Pedro.) I'll merge this into my version in the coming days. > The __eh_continue.S was directly copied from cegcc... The __asm__ blocks took me a bit to get right, until I realized I was mapping bit fields into shifts completely mirrored. They do more or less what the compiler would emit if it had basic support for SEH. Looking at a few examples on the web, it seems to be safe to throw from a SEH handler, but still not convinced that is safe, especially for CE/ARM/Risc SEH. That being said, the asm/'thread context handling' code I posted could certainly be simplified. Cheers, Pedro Alves ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ Cegcc-devel mailing list Cegcc-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/cegcc-devel
