Re: [CRIS] dwarf2 frame sniffer problem?

[Daniel Jacobowitz <drow@false.org>]

On Tue, Mar 16, 2004 at 05:26:16PM +0100, Orjan Friberg wrote:
> Daniel Jacobowitz wrote:
> >
> >I see that your GCC port uses textual prologues.  As it happens, I just
> >implemented dwarf generation for that mechanism (for Thumb), so I know
> >how it's supposed to work.  Here's your problem.  First you have:
> >
> >      /* FIXME: Slightly redundant calculation, as we do the same in
> >         pieces below.  This offset must be the total adjustment of the
> >         stack-pointer.  We can then def_cfa call at the end of this
> >         function with the current implementation of execute_cfa_insn, but
> >         that wouldn't really be clean.  */
> >
> >      cfa_label = dwarf2out_cfi_label ();
> >      dwarf2out_def_cfa (cfa_label, cfa_reg, cfa_offset);
> >
> >but that label is at the beginning of the function, so this is
> >incorrect.  That's not what the CFA is at the beginning of the
> >function.
> 
> Would emitting that label *after* the prologue be an option (i.e. 
> leaving us without dwarf2 information while still in the prologue)?

Nope.  Then when you step into the prologue (i.e. "step over") unwind
information will be incorrect.

I recommend taking a look at the patch where I implemented this for
Thumb, or at the m68k implementation.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer