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Re: __float128 typeinfo
- From: Richard Earnshaw <Richard dot Earnshaw at buzzard dot freeserve dot co dot uk>
- To: Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>, Marc Glisse <marc dot glisse at inria dot fr>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>, Jason Merrill <jason at redhat dot com>, "libstdc++ at gcc dot gnu dot org" <libstdc++ at gcc dot gnu dot org>, "meissner at linux dot vnet dot ibm dot com" <meissner at linux dot vnet dot ibm dot com>
- Date: Sat, 07 Jun 2014 02:14:13 +0100
- Subject: Re: __float128 typeinfo
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot DEB dot 2 dot 02 dot 1406061049520 dot 8194 at stedding dot saclay dot inria dot fr> <CAJA7tRYAPyvyR9jp8do+f9UG2BrB5fwBa2Qk=c0has9XuUK58A at mail dot gmail dot com>
On 06/06/14 16:25, Ramana Radhakrishnan wrote:
> On Fri, Jun 6, 2014 at 3:16 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
>> Hello,
>>
>> here is a new try on adding __float128 typeinfo to libsupc++. The front-end
>> part is based on the discussion with Jason yesterday. The libstdc++ part is
>> copied from:
>> https://gcc.gnu.org/ml/libstdc++/2014-04/msg00077.html
>> (which wasn't reviewed), but I changed the testsuite.
>>
>> Michael will likely need to make some adjustments to his __float128 patch,
>> but I believe it will only be a small configure tweak.
>>
>> Ramana, does it look safe for ARM? By the way, do you want to remove the
>> XFmode defined in arm-modes.def and apparently unused?
>
> Thanks for this though I know Tejas is actually trying to fix AArch64
> first and then we'll move on to ARM for cleaning up all these types -
> as you realize it's quite a chunky project.
>
> A patch to remove XFmode is pre-approved. I have no idea why this is
> in here. Archeaology shows this came in
>
> git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@72440
>
> and with a FIXME:
>
> I'll try and have a look at this patch later today or over the weekend
> to see if it doesn't affect ARM / AArch64.
>
XFmode should have been removed on ARM when the FPA code was expunged.
In fact, it was only briefly used on ARM many, many, years ago when I
tried to use the FPA's extended double-precision format for long double.
That change was backed out when it turned out that some machines of
that era would hang hard (BRS time) in the RISC iX kernel due to a bug
in the floating-point emulation code for handling denormals.
R.