Re: Fix backtrace for interpreted code

[Andrew Haley <aph at redhat dot com>]

Ranjit Mathew writes:
 > >  > >Surely it's better to fix MD_FALLBACK_FRAME_STATE_FOR to unwind
 > >  > >through SEH frames.  That would bring many benefits.
 > >  >
 > >  > Indeed. If we want proper stack traces on Windows - particularly
 > >  > ones that are good enough for the security model, this must be
 > >  > done.
 > > 
 > > There's example code at
 > > http://www.jorgon.freeserve.co.uk/ExceptFrame.htm.  There are more
 > > examples and some patches on the net.  As I see it, we don't need to
 > > provide full SEH support, only to unwind through an SEH frame.  Is
 > > there some specific problem anyone here knows about?
 > 
 > (Disclaimer: I have not worked on the Win32 port in more than a
 > year now.)
 > 
 > I think there's a mix-up here. If we are wondering why MinGW/Cygwin
 > doesn't use DWARF-2 EH by default, it is not simply because of SEH
 > frames.
 > 
 > The primary issue (as I recall it) is that DWARF-2 based unwinding
 > cannot handle "alien" frames on the call stack

Sure it can -- that's what MD_FALLBACK_FRAME_STATE_FOR is for.  It's
just a matter of writing it.

Andrew.