Re: patch for printing 64-bit values in i386 registers; STABS format

Daniel Jacobowitz
2003-04-28T16:14:50Z

On Mon, Apr 28, 2003 at 12:08:17PM -0400, Andrew Cagney wrote:
>
> >>The stabs reader will need to be modified so that it generates a proper
> >>location description. Note that it is STABS centric. dwarf2 doesn't
> >>need that mechanism since (presumably) GCC is generating the correct
> >>info (....).
> >
> >
> >No, that's incorrect. GDB wouldn't even be able to find half the value
> >if GCC was putting out correct information. We can't fix that until
> >GDB is ready to not choke on the result. We will have to handle the
> >incorrect debug info probably forever.
>
> I made two assertions:
>
> - stabs
> - dwarf2 (where I included a ``presumably'')
>
> You're saying that both are incorrect?

I guess that depends where you draw the line between the two assertions
:)

- It's not stabs centric; I imagine that if someone went in to update
mdebug or hp support they'd have the same problem. Well, maybe not hp.
That's a real kitchen sink format from what I recall.

- generated dwarf2 is not correct

but

- stabs would have to be modified (if we did this fixup in each and
every debug reader, instead of in read_var_value and friends; I see
good arguments both ways)

> >This is one of the intended purposes of this mechanism, and as I
> >>indicated, is needed by MIPS. Being able to project an arbitrary [debug
> >>info] view of the registers onto the raw register buffer.
> >>
> >>BTW, what happens when there is an attempt to write a long long value?
> >>GDB again assumes that it can write to contigious registers - the reason
> >>why REGISTER_BYTE can't be killed.
> >
> >
> >That ugliness could go away too with Mark's introduced method. GDB
> >could be fixed to find the next register properly.
>
> GDB also uses it to encode offsets into a register. It also does not
> help the MIPS where the debug register does need to be projected into
> the raw registers. Why have add more mechanisms when the existing one
> is sufficient. Focus the effort on fixing the real problem.
>
> BTW, my comment about no names was wrong. They can be named, that
> restriction should have been removed by the introduction of reggroups.

Well, in that case I guess it would work. Let's do it?

It still feels much more like a hack to me than Mark's approach; I'll
just quietly disagree I suppose.

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer