From: Joseph Myers <joseph@codesourcery.com>
To: Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
Cc: Jonathan Wakely <jwakely@redhat.com>, <gcc-patches@gcc.gnu.org>
Subject: Re: Prevent all uses of DFP when unsupported (PR c/91985)
Date: Wed, 27 Nov 2019 17:49:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.21.1911271745260.3858@digraph.polyomino.org.uk> (raw)
In-Reply-To: <ydd36e9h85b.fsf@CeBiTec.Uni-Bielefeld.DE>
On Wed, 27 Nov 2019, Rainer Orth wrote:
> Hi Jonathan,
>
> > On 26/11/19 00:57 +0000, Joseph Myers wrote:
> >>On Mon, 25 Nov 2019, Rainer Orth wrote:
> >>
> >>> and a few more, all DFP related. They used to be emitted by g++ for
> >>> __fundamental_type_info in libsupc++/fundamental_type_info.cc and lived
> >>> in the CXXABI_1.3.4 version. However, since Solaris *does* lack DFP
> >>> support, that's no longer the case. I'm uncertain how best to deal with
> >>> this, however.
> >>
> >>As I understand it, _GLIBCXX_USE_DECIMAL_FLOAT should already have been
> >>undefined for this target, and so std::decimal::decimal32 etc. should not
> >>have been usable (both the header not working without that define, and the
> >>mode attributes in the header being rejected by the front end when DFP is
> >>unsupported). I.e. such defines in libsupc++ would never have been usable
> >>on this target, so I think they are something it should be safe to remove
> >>from the ABI baseline.
> >
> > If it's actually impossible that any real program could have depended
> > on those symbols, then I agree.
>
> this is exactly what I've got no way of telling, that's why I was asking
> for guidance. Just removing the DFP symbols from the baselines works,
> of course.
I don't think any real program could have used those symbols; it would
have required using __typeof (__builtin_fabsd32 (0)) or similar to access
types that weren't normally available for those targets (and by accessing
the types using builtins like that, you're getting a completely undefined
function-calling ABI for them anyway).
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2019-11-27 17:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-22 16:47 Joseph Myers
2019-11-23 16:56 ` Jeff Law
2019-11-25 20:36 ` Rainer Orth
2019-11-26 1:05 ` Joseph Myers
2019-11-26 12:21 ` Jonathan Wakely
2019-11-27 12:18 ` Rainer Orth
2019-11-27 17:49 ` Joseph Myers [this message]
2019-11-27 18:01 ` Jakub Jelinek
2020-01-16 14:49 ` Szabolcs Nagy
2020-01-16 14:50 ` Jakub Jelinek
2019-11-26 14:02 ` Andreas Schwab
2019-11-27 21:55 ` Thomas Schwinge
2019-11-27 22:39 ` Joseph Myers
2019-11-28 14:22 ` Thomas Schwinge
2019-11-28 14:44 ` [PATCH] Fix decimal floating-point LTO streaming for offloading compilation Julian Brown
2019-11-28 15:15 ` Joseph Myers
2019-11-28 15:45 ` Segher Boessenkool
2019-11-28 18:25 ` Julian Brown
2019-11-28 19:22 ` Joseph Myers
2019-11-28 19:45 ` Richard Biener
2019-11-28 15:23 ` Thomas Schwinge
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