This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [PATCH 8/17][ARM] Add VFP FP16 arithmetic instructions.
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Matthew Wahab <matthew dot wahab at foss dot arm dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 18 May 2016 00:56:52 +0000
- Subject: Re: [PATCH 8/17][ARM] Add VFP FP16 arithmetic instructions.
- Authentication-results: sourceware.org; auth=none
- References: <573B28A3 dot 9030603 at foss dot arm dot com> <573B2C4E dot 4090900 at foss dot arm dot com> <alpine dot DEB dot 2 dot 20 dot 1605180033070 dot 6325 at digraph dot polyomino dot org dot uk>
On Wed, 18 May 2016, Joseph Myers wrote:
> But why do you need to force that? If the instructions follow IEEE
> semantics including for exceptions and rounding modes, then X OP Y
> computed directly with binary16 arithmetic has the same value as results
> from promoting to binary32, doing binary32 arithmetic and converting back
> to binary16, for OP in + - * /. (Double-rounding problems can only occur
I should say: this is not the case for fma - (__fp16) fmaf (a, b, c) need
not be the same as fmaf16 (a, b, c) for fp16 values a, b, c - but I think
you should use the standard instruction name there as well - if the
instruction is a fused multiply-add on binary16, it should be described as
such.
--
Joseph S. Myers
joseph@codesourcery.com