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Re: stdcall lib functions with exception throwing callbacks vs Dwarf2 EH
- From: Danny Smith <dannysmith at clear dot net dot nz>
- To: Richard Henderson <rth at redhat dot com>
- Cc: gcc at gcc dot gnu dot org, Cygwin <cygwin at cygwin dot com>, mingw-dvlpr <mingw-dvlpr at lists dot sourceforge dot net>
- Date: Wed, 24 Nov 2004 21:09:52 +1300
- Subject: Re: stdcall lib functions with exception throwing callbacks vs Dwarf2 EH
- References: <001701c4d1ab$949322e0$0a6d65da@DANNY> <20041124003240.GA6028@redhat.com>
- Reply-to: Danny Smith <dannysmith at users dot sourceforge dot net>
Richard Henderson wrote:
> On Wed, Nov 24, 2004 at 11:27:11AM +1300, Danny Smith wrote:
>> Before I pull any more hair out trying, does any one have any hints
>> on how to use an MD_FALLBACK_FRAME_STATE_FOR to workaround ...
>
> That would be wrong.
>
> I think the most likely explanation is that there's a bug in the
> dwarf2 generator for stdcall functions with -fomit-frame-pointer,
> and the problem should be attacked there.
>
There does seem to be a problem in the frame-pointer handling see:
http://gcc.gnu.org/ml/gcc/2002-11/msg00149.html
With this testcase:
void __attribute__((stdcall)) test( int a) { a; }
void snafu( void) {
test( 666);
throw 999;
}
int main( void) {
try {
snafu( );
return 0;
} catch( ...) {
return 1;
}
}
I get (today):
g++ -fno-omit-frame-pointer PASS (at all optimisation levels).
g++ -O{0|1|2} -fomit-frame-pointer -maccumulate-outgoing-args PASS.
g++ -O0 -mtune=i686 -mno-accumulate-outgoing-args -fomit-frame-pointer
FAIL
g++ -O{1,2} -mtune=i686 -mno-accumulate-outgoing-args -fomit-frame-poi
nter PASS
The optimisation flags that cause failure has changed since the original
gcc report.
Danny
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