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

Daniel Jacobowitz
2003-04-26T04:32:02Z

On Fri, Apr 25, 2003 at 11:32:47PM -0400, Andrew Cagney wrote:
>
> >I'm afraid I don't understand, and I still don't see your reasoning
> >against this approach.
>
> It isn't necessary, just like register convertible and register
> raw/virtual size; .... that go before it, also were not necessary. And
> now all these years later, GDB is still yet to expunge.
>
> Until someone does the right think - add support for values scattered
> across registers and memory - hacks should be confined to architecture
> specific code.

I think the hack of introducing unnamed pseudo registers for this
purpose would do a lot more harm and cause a lot more problems; I guess
I just have to disagree with your reaction here.

Think about the day when we have proper support for DW_OP_piece. For
compatibility with current debug info we're going to have to have a way
for the debug reader to ask the architecture "if I have a value of this
size listed as living in this register, where (probably) is it really
stored?". That is _exactly_ the same question. Asking it would move
from read_var_value to stabsread/dwarf2read, but the interface would
have to be just the same.

That's why I see Mark's patch as a monotonic step forwards. And it
fixes a real problem. We have to fix problems eventually, you know -
and no one has taken the initiative to implement scattered values. I
tried. It was a major pain; after a day working on it, I went back to
other projects.

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer