Re: debug/1621: Debugging with complex numbers

[Daniel Jacobowitz <drow at mvista dot com>]

On Wed, Dec 11, 2002 at 07:05:47PM -0500, Jim Wilson wrote:
> About the $imag, $real stuff in the gcc/doc/extend.texi file...
> The part about "None of the supported debug info formats..." is obsolete.
> DWARF2 location descriptions can handle this easily, and this is already
> supported in dwarf2out.c.  Perhaps also DWARF, but I don't care enough to look
> it up.  The stabs hack of emitting two foo$imag and foo$real symbols is ugly
> and should be discouraged.  I don't think it makes any sense to teach gdb
> about this hack.  We should instead encourage use of DWARF2, which we are
> already doing.

I agree.

> I tried writing a patch to make gcc use the Solaris 'R' stab letter extension.
> 
> This brings up a number of questions.  Sun only defined 3 float and 3 complex
> float types.  However, we have 7 float types and 6 complex float types.  (They
> should be the same, but that is a different problem.)  Do we extend the
> Solaris extension to meet our needs?  Or fall back on the problematic 'r'
> letter when we can't use 'R'?  Extending 'R' might make us incompatible with
> Sun if in the future Sun extends it too, so trying to discuss it with Sun is
> a good idea.  Or perhaps invent our own similar extension that won't conflict
> with Sun?

First of all, for floating point types we could just continue to use
'r'.  It's not problematic in that case.  On the other hand consistency
is nice.

I recommend emitting just the generic NF_COMPLEX and NF_FLOATING (?)
for any of the unknown types.  GDB only uses the type to determine if
it is a floating or complex type, so that will suffice.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer