mingw compile issues

Lucas Fisher lucas.fisher at gmail.com
Wed Nov 9 20:42:54 EST 2011

Yeah, I'm using mingw-gcc 4.6.1.  Looking around online it looks like
others are having this issue with -O2 which is used by Pidgin's win32
build. I modified CFLAGS in libpurple/win32/global.mak to use -O0
instead and no more crashes.

Also, when compiling with mingw-gcc -O2 exchndl.dll causes a crash on
startup. If I get remove exchndl.dll it doesn't crash on startup. That
crash also goes away with -O0.


On Wed, Nov 9, 2011 at 7:15 PM, Daniel Atallah <daniel.atallah at gmail.com> wrote:
> On Mon, Nov 7, 2011 at 21:28, Lucas Fisher <lucas.fisher at gmail.com> wrote:
>> I'm compiling im.pidgin head on Windows roughly following
>> http://developer.pidgin.im/ticket/14678.  I was able to get this
>> compiling and sort out all the dependencies.  However, I found that
>> Pidgin would crash when you quit.  I traced this to WinMain in
>> pidgin/win32/winpidgin.c. It crashes because when WinMain returns the
>> stack pointer is not pointing to the return address, but other data on
>> the stack. It almost looks like the compiler is messing up and
>> generating the wrong instructions. When I turn off optimizations this
>> problem goes away.
>> Has anyone else seen this behavior?
>> Lucas
>> Relevant code:
>> loc_40213A:
>> mov     [esp+0CACh+var_CAC], edi
>> call    LocalFree
>> push    ecx
>> mov     [esp+0CACh+var_CA4], ebp
>> mov     [esp+0CACh+var_CA8], esi
>> mov     eax, [esp+0CACh+hInstance]
>> mov     [esp+0CACh+var_CAC], eax
>> call    ds:dword_408024   # is the calling convention correct here?
>> sub     esp, 0Ch            # this instruction misaligns the stack pointer
>> add     esp, 0CACh
>> pop     ebx
>> pop     esi
>> pop     edi
>> pop     ebp
>> retn    10h
> Which version of gcc are you using to build?
> I've seen some weirdness with optimizations in mingw gcc 4.6.
> -D

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