#168 unhandled exception filter not called in 64-bit

[Oliver Stöneberg]

The Windows API function SetUnhandledExceptionFilter() lets you set a function, that is being called in case of unhandled exception. But this is only called with the 32-bit version of mingw64. I confirmed it is working in Visual Studio 2010 with a 32-bit and a 64-bit compile. I will provide a sample later if necessary.

The working 32-bit version:
Using built-in specs.
Target: i686-w64-mingw32
Configured with: ../gcc44-svn/configure --target=i686-w64-mingw32 --host=i686-w64-mingw32 --disable-multilib --disable-nls --prefix=/mingw64-w32 --with-sysroot=/mingw64-w32 --with-gmp=/mingw64-w32 --with-mpfr=/mingw64-w32 --enable-languages=c,c++
Thread model: win32
gcc version 4.4.3 20091223 (prerelease) r155431 (GCC)

The 64-bit version in question:
Using built-in specs.
Target: x86_64-w64-mingw32
Configured with: ../gcc44-svn/configure --target=x86_64-w64-mingw32 --host=x86_64-w64-mingw32 --disable-multilib --disable-nls --prefix=/mingw64 --with-sysroot=/mingw64 --with-gmp=/mingw64 --with-mpfr=/mingw64 --enable-languages=c,c++
Thread model: win32
gcc version 4.4.3 20091223 (prerelease) r155431 (GCC)

These are actually the personal compiles from sezero offered by the mingw64 page.

[Kai Tietz]

Hello,

The function SetUnhandledExceptionFilter is getting overriden by newer msvcrt runtimes. There can be found some interesting articles by using a search-engine.
The issue is, that gcc doesn't have the SEH feature for x64 (the x86 is quite different here), which is necessary for having the support of user-mode exception-filters.
So for this you have to wait until gcc is able to generate for x64 SEH unwind-information, then you will see the same behavior as for VC.

Regards,
Kai

[Ivan Maidanski]

Hi!

BoehmGC uses SetUnhandledExceptionFilter() in the incremental mode (e.g., compile GC v7.2a4 test.c using the following command line: gcc -DALL_INTERIOR_POINTERS -DGC_PREFER_MPROTECT_VDB -I.\include -s tests\test.c *.c -luser32).

As a test case, the following could be used:

#include <setjmp.h>
#include <stdio.h>
#include <windows.h>

int *ptr = NULL;
jmp_buf buf;

LONG WINAPI handler(struct _EXCEPTION_POINTERS *exc_info)
{
longjmp(buf,1);
}

int main(void)
{
SetUnhandledExceptionFilter(handler);
if (!setjmp(buf)) {
*ptr = 0;
printf("FAILED\n");
} else {
printf("PASSED\n");
}
return 0;
}

[Ivan Maidanski]

I wonder: is there a macro that indicates whether the compiler is able to generate for x64 SEH unwind-information.

[Kai Tietz]

Yes, for 4.6 (which is actual the first version providing for x64 SEH frame unwind-information) there is __SEH__ defined. For an classical C exception handler example you can take a look into our crtexe.c file.

Kai

[Kai Tietz]

Issue is fixed for gcc 4.6 and newer compiler version together with trunk, 2.x, and even for 1.0 (IIRC). So close that bug as fixed.