[rfc] trad-frame change

[Andrew Cagney]

>>> So there are really two variants - o32sigreturn and rt_sigreturn (with 
>>> constants computed from the architecture vector)?
> 
> 
> I don't see much point in distinguishing them that way, honestly.  The
> difference between o32 sigreturn and o32 rt_sigreturn is about the same
> as the difference between n32 and n64.  Sure, you could put the
> constants in the architecture tdep vector... but why bother?
> 
> And it may be silly, but there's nothing stopping a theoretical
> hand-written program from using a different ABI's sigreturn syscall.

Like you said, theoretical - program for what is, not what might be, but 
what ever.

>>>> >What would _really_ be nice would be a way to pass the kind from the
>>>> >sniffer (which really just calls PC_IN_SIGTRAMP) to the frame creation
>>>> >code... not have to read inferior memory to figure out which it is,
>>>> >twice.
>>
>>> 
>>> I'll think about that, I may need to change the unwinder object anyway.
>>> 
>>> Just remember that it is the number of unique addresses accessed (0 vs 1 
>>> vs 2 ...) and not the number of times each address is accessed that is 
>>> going to be important - multiple accesses to a single address can be 
>>> handled with a cache.
> 
> 
> We really should turn on that cache someday.

Not that cache, a new one, yes, someday.

Andrew