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Date: Wed, 10 Aug 2022 15:04:00 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Cc: Michael Meissner via Gcc <gcc@gcc.gnu.org>,
 Michael Meissner <meissner@linux.ibm.com>,
 "Kewen.Lin" <linkw@linux.ibm.com>, David Edelsohn <dje.gcc@gmail.com>,
 Peter Bergner <bergner@linux.ibm.com>,
 Will Schmidt <will_schmidt@vnet.ibm.com>,
 Jason Merrill <jason@redhat.com>, Nathan Sidwell <nathan@acm.org>,
 Mike Stump <mikestump@comcast.net>, Iain Sandoe <iain@sandoe.co.uk>,
 Joseph Myers <joseph@codesourcery.com>, Alan Modra <amodra@gmail.com>,
 Nick Clifton <nickc@redhat.com>, Jeff Law <jlaw@tachyum.com>,
 Jakub Jelinek <jakub@redhat.com>, Richard Biener <rguenther@suse.de>,
 "David S. Miller" <davem@redhat.com>,
 "Carlos O'Donell" <carlos@redhat.com>, libc-alpha@sourceware.org
Subject: Re: Resend: Potential upcoming changes in mangling to PowerPC GCC
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On Wed, Aug 10, 2022 at 04:55:42PM -0300, Tulio Magno Quites Machado Filho wrote:
> Michael Meissner via Gcc <gcc@gcc.gnu.org> writes:
> > Because long double mangles the same as either __float128 or __ibm128, you
> > cannot write programs like:
> >
> > 	double convert (__ibm128    x) { return x; }
> > 	double convert (__float128  x) { return x; }
> > 	double convert (long double x) { return x; }
> >
> > You would have to write on a system with long double being IBM 128-bit:
> >
> > 	double convert (__float128  x) { return x; }
> > 	double convert (long double x) { return x; }
> >
> > or on a system with long double being IEEE 128-bit:
> >
> > 	double convert (__ibm128    x) { return x; }
> > 	double convert (long double x) { return x; }
> 
> Does that mean, when long double is IEEE 128-bit, the compiler won't support
> _Float128/__float128 ?

You can write
	double convert (__ibm128  x) { return x; }
	double convert (__ieee128 x) { return x; }
as well.  "__ieee128" and "long double" are the same type then (and the
same as _Float128 and __float128 as well).


Segher