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Re: [PATCH/AARCH64] Decimal floating point support for AARCH64
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Andrew Pinski <apinski at cavium dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 28 Jul 2017 18:03:07 +0000
- Subject: Re: [PATCH/AARCH64] Decimal floating point support for AARCH64
- Authentication-results: sourceware.org; auth=none
- References: <CA+=Sn1ktkQiRKcSxO4sYQiFW8cYLfzbNV+4no33gD7xvx++y8A@mail.gmail.com>
On Thu, 13 Jul 2017, Andrew Pinski wrote:
> Hi,
> This patch adds Decimal floating point support to aarch64. It is
> the base support in that since there is no hardware support for DFP,
> it just defines the ABI. The ABI I chose is that _Decimal32 is
> treated like float, _Decimal64 is treated like double and _Decimal128
> is treated like long double. In that they are passed via the floating
> registers (sN, dN, qN).
> Is this ok an ABI?
Shouldn't you also change config/dfp.m4 and regenerate affected configure
scripts?
Are you using DPD or BID encoding? What's the rationale for your choice
between them? (x86 uses BID, software only; POWER and S/390 use DPD, and
have some hardware support.) I'd then expect that choice to be documented
in install.texi (though that seems out-of-date regarding S/390).
Any plans for other software such as libdfp? (FWIW, whereas GCC defaults
to DPD for architectures not otherwise configured in dfp.m4, libdfp
defaults to BID for architectures other than POWER / S/390.)
Are you working with the AAPCS64 document maintainers to get DFP support
added there?
--
Joseph S. Myers
joseph@codesourcery.com