Bug#826749: RE: clang: enable FPXX for o32 by default

[Pablo Oliveira]

Dear all,

Thanks for clarifying the issue. Having support for a configure-time
option would be great. In the meantime I have applied YunQiang Su's
patch on 3.7/3.8 and snapshot in the package svn,

  [ YunQiang Su ]
  * Enable FPXX by default on mips/mipsel (Closes: #826749)

Thanks !

Pablo


On Mon, 13 Jun 2016 16:34:42 +0000 Daniel Sanders
<Daniel.Sanders at imgtec.com> wrote:
> > -----Original Message-----
> > From: Matthew Fortune
> > Sent: 13 June 2016 16:55
> > To: YunQiang Su; Pablo Oliveira
> > Cc: 826749 at bugs.debian.org; Sylvestre Ledru; Daniel Sanders
> > Subject: RE: clang: enable FPXX for o32 by default
> > 
> > YunQiang Su <wzssyqa at gmail.com> writes:
> > > On Fri, Jun 10, 2016 at 12:10 AM, Pablo Oliveira <pablo at sifflez.org>
> > > wrote:
> > > > Dear YunQiang Su,
> > > >
> > > > On Wed, 8 Jun 2016 23:49:17 +0800 YunQiang Su <wzssyqa at gmail.com>
> > > wrote:
> > > >> Package: src:llvm-toolchain-snapshot
> > > >>
> > > >> We are working on moving all packages mips/mipsel built with
> > > >> fpxx-enabled by default.
> > > >>
> > > >> While, now fpxx is not enabled by default in clang.
> > > >> So please apply the attached patch to 3.5/3.6/3.7/3.8/snapshot.
> > > >>
> > > >> About FPXX and the transaction, please see:
> > > >>
> > > >> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=825342
> > > >
> > > > Are you sure it is ok to modify the default behavior of FPXXDefault
> > > > only for Debian clang packages (this could lead to surprise and hard
> > > > to track bugs for users) ?
> > >
> > > The clang guy in IMG told me that this the only way currently.
> > >
> > > >
> > > > To me it makes more sense to:
> > > >
> > > > 1) either submit this patch upstream, so that every clang distribution
> > > > has the same common behavior regarding FPXX
> > >
> > > I also prefer this way.
> > 
> > We cannot do this as the topic we are discussing here is inherently a
> > decision for distributions and not upstream. Please note the setting for
> > this in GCC is a build time setting so upstream GCC does not set FPXX
> > by default. Fedora or other distros can choose different compatibility
> > levels that suit their user base and hence may not use FPXX.
> > 
> > There is a longer term plan to get a build time configuration option into
> > CLANG/LLVM but this will take time to plan and implement. When ready
> > you can switch to it but there is no ETA.
> 
> My plan on this is a bit of a compromise between these two positions so I think I
> should elaborate a little. I aim to collect all the distribution specific behaviours
> upstream and have each distribution use a configure-time option to pick between
> them. This allows people to cross compile to specific distributions and should
> help limit any confusion caused by the configure-time option.
> 
> One possible way of going about this is to have a mips-debian-linux-gnu triple in
> upstream clang that has all the Debian-specific behaviours and have Debian use a
> configure-time option to map mips-linux-gnu to mips-debian-linux-gnu.
>