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Re: [rfc] Add some more floatformat types ....
- To: Andrew Cagney <ac131313 at cygnus dot com>
- Subject: Re: [rfc] Add some more floatformat types ....
- From: Mark Kettenis <kettenis at science dot uva dot nl>
- Date: 17 Aug 2001 01:53:41 +0200
- Cc: gdb-patches at sources dot redhat dot com, binutils at sources dot redhat dot com
- References: <3B76164B.9060908@cygnus.com> <3B7C1287.9080906@cygnus.com>
Andrew Cagney <ac131313@cygnus.com> writes:
> > The attached adds the floatformats:
> >
> > floatformat_i387_ext80;
> > floatformat_i387_ext96;
> >
> > Explicitly sized x86 float formats.
> >
> > Depending on where/how it is stored,
> > an i386 extended could use 80 (10 bytes)
> > or 96 (12 bytes).
Andrew, I thought I (implicitly) raised some objections to this
change. See
http://sources.redhat.com/ml/gdb/2001-07/msg00401.html
To clarify things a bit: The ISA (that stands for Istruction Set
Architecture doesn't it) defines a single 80-bit extended floating
point format. On top of that floating point format most ABI's build a
a 96-bit extended floating point type (e.g. GCC's `long double'). I'd
like GDB to somehow maintain this concept, by *not* introducing the
floatformat_i387_ext80 and floatformat_i387_ext96 types you propose.
Instead we should make the distinction at the builtin_type_* level.
By making the 80-bit and 96-bit builtin_type_* variants share the same
underlying floatformat_* variable, we can easiliy check whether two
floating point formats on the ABI level share the same encoding on the
ISA level.
Something similar might hold for IA-64.
The other two fixes seem obvious to me.
Mark