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Re: [RFC] frame_id_inner check and -fsplit-stack
On Wed, Dec 30, 2009 at 12:06:09AM -0800, Ian Lance Taylor wrote:
> Looking at DWARF, I see that there is a calling_convention enum which
> can be added to the DW_TAG_subprogram for a function. I don't know all
> that much about DWARF; does that seem like the right sort of thing to
> do?
No. The split-stack-ness doesn't affect how the function is called;
the attribute's for cases like regparm.
> That wouldn't help with the unwind info, though. There I think we could
> add a new augmentation code for a split-stack function. The presence of
> the augmentation would mean that the stack might be out of order when
> unwinding through this function. I think that would work because
> unwinders which didn't recognize it would simply ignore it. But again I
> am far from being an expert in this area.
An augmentation ought to work for this. Similarly, GDB could check
for the prologue sequence if there is no unwind info.
Didn't we have another report that the inner-than check was causing
trouble, just a few months ago? I think it had to do with the Linux
kernel, but I can't find the details. This check causes a lot of
trouble.
--
Daniel Jacobowitz
CodeSourcery