Unwind API for EH

[Jason Merrill]

>>>>> Eli Boling <eboling at inprise.com> writes:

 >> > Date: Thu, 24 Aug 2000 17:30:18 -0500
 >> > From: "Eli Boling" <eboling at inprise.com>
 >> >
 >> > I actually prefer the SetGR interface.  The reason is this:  The
 >> > current unwind ABI can be changed with relative ease to support IA32,
 >> > as well as IA-64.  This is helped by the current form of SetGR.
 >> 
 >> Why isn't that just as true of Cary's suggestion?  Or even more so,
 >> since his doesn't imply specific registers in the interface for landing
 >> pad parameters?

 > It can be done either way, but I don't think that making the interface more
 > specific (to landing pad regs) helps very much.  The idea that Cary had (I
 > think) was that a more restricted interface be used to narrow the registers
 > that would be considered available to suit a need specific to the IA64 -
 > not stomping on regs that you're not supposed to tromp on because the Intel
 > ABI says not to.

I think the idea was more to generalize the interface: there are N values
that you want to communicate to the landing pad.  It doesn't matter which
registers you use to pass these.  For a register-poor architecture like the
ia32, you might even combine the values into a struct and use only a single
register.  Cary's suggestion allows us to leave this decision up to the
unwinder library, so the personality routine can be more general.

Jason