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Re: RFA: DW_AT_frame_base fix for complicated frames
On Thu, Oct 02, 2003 at 12:54:32PM -0500, Jim Blandy wrote:
>
> Daniel Jacobowitz <drow@mvista.com> writes:
> > Does anyone remember a specific reason why this code was there? I don't,
> > and I rewrote all of this stuff... I am 99.99% sure it's based on the unwind
> > handling for saved registers, where we get either a register number or the
> > address of a stack slot. But for frame bases that's not true:
> >
> > A subroutine or entry point entry may also have a DW_AT_frame_base
> > attribute, whose value is a location description that computes the "frame
> > base" for the subroutine or entry point.
> >
> > i.e. it computes the frame base. Not the address of the frame base. This
> > memory read tends to find (on x86) the return address, and then we think the
> > stack is at <main+34>. Oopsie.
> >
> > OK? With this patch and some code Daniel Berlin and Joseph are working on,
> > location lists actually work. I can see all the arguments in an
> > -fomit-frame-pointer function from the beginning. It's really quite cool.
>
> I think you're right, there's no reason for that memory fetch to be
> there. Please commit.
Thanks. I've committed this to trunk and branch. I also moved this to
the branch:
2003-10-09 Daniel Jacobowitz <drow@mvista.com>
Merge from mainline:
2003-07-31 Daniel Jacobowitz <drow@mvista.com>
* dwarf2read.c (new_symbol): Use var_decode_location for parameters.
Location expressions and lists should work reasonably well on both now.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer