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Message-ID:	<41A44B97.1060007@aaronwl.com>
Date:	Wed, 24 Nov 2004 02:51:35 -0600
From:	"Aaron W. LaFramboise" <aaronavay62 AT aaronwl DOT com>
User-Agent:	Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.3) Gecko/20040910
MIME-Version:	1.0
To:	Richard Henderson <rth AT redhat DOT com>
CC:	Danny Smith <dannysmith AT users DOT sourceforge DOT net>, gcc AT gcc DOT gnu DOT org,
	Cygwin <cygwin AT cygwin DOT com>, mingw-dvlpr <mingw-dvlpr AT lists DOT sourceforge DOT net>
Subject:	Re: stdcall lib functions with exception throwing callbacks vs Dwarf2 EH
References:	<001701c4d1ab$949322e0$0a6d65da AT DANNY> <20041124003240 DOT GA6028 AT redhat DOT com> <000c01c4d1fa$3f297fd0$e56d65da AT DANNY> <20041124080708 DOT GA3578 AT redhat DOT com>
In-Reply-To:	<20041124080708.GA3578@redhat.com>

Richard Henderson wrote:

> On Wed, Nov 24, 2004 at 08:50:17PM +1300, Danny Smith wrote:
> 
>>So is it a general requirements of DW2 EH that functions that are passed
>>callbacks as args  be compiled with -fexceptions,  if the callbacks may
>>throw?
> 
> Yes.  Thus glibc compiles e.g. qsort and bsearch with -fexceptions.

Is there a way to have the DW2 unwinder call some particular function,
for eg, if the previous frame was not compiled with -fexceptions, rather
than just crashing?  Is this what MD_FALLBACK_FRAME_STATE_FOR is for?

Other Windows compilers are able to handle this condition.  I don't know
anything at all about MSVC's non-SEH exception handling, and I have not
done any analysis at all, but it seems likely that these compilers are
unwinding SEH information in foreign frames.  If this is the case,
compatibility with this is highly desirable, and perhaps essential for
throwing through system routines that use SEH, which is something other
compilers on the system support.

Aaron W. LaFramboise

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