Re: debug/1621: Debugging with complex numbers

[Daniel Jacobowitz <drow at mvista dot com>]

On Thu, Dec 12, 2002 at 10:55:17AM -0500, Jim Wilson wrote:
> >I recommend emitting just the generic NF_COMPLEX and NF_FLOATING (?)
> >for any of the unknown types.
> 
> NF_COMPLEX is supposed to be IEEE single complex.  There is no generic
> value for complex types.  However, I do see your point, since we have the
> type size anyways, we don't really need to distinguish between the different
> complex types for IEEE FP targets.
> 
> There is a problem if we want to distinguish between IEEE and non-IEEE FP,
> in which case the type size is not enough.  For instance, most RISC targets
> use a 128-bit IEEE double-extended type.  However, some powerpc targets use
> a 128-bit non-IEEE IBM pair-of-doubles type.  We can distinguish between these
> two only if we have a special NF_* value for the IBM pair-of-doubles type.
> Or alternatively, gdb just has to know that some targets use a non-IEEE long
> double type.  This is different problem from the one we are trying to fix
> though, and can be postponed for now.

Right.  GDB already has a different mechanism to handle this case, so
I'm not terribly worried about the details of using stabs and IEEE long
double on a non-IEEE platform in this circumstance.

> >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.
> 
> My patch continues to use 'r' for floating point types for now.  I didn't
> want to break backwards compatibility for other stabs targets.  'R' will
> presumably only work on the Sun debugger and gdb.  It is OK to use 'R' for
> complex because it is an GNU C extension to ISO C90, so users can't expect
> old debuggers to handle it correctly.

Didn't you generate some 'R' entires for REAL_TYPE in the previous
patch?

> I will modify my patch to use NF_COMPLEX and NF_SINGLE as generic FP type
> descriptors and add appropriate comments about what we are doing in order
> to fix GCC PR debug/1621.

Thank you!

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer