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Re: fminnm/fmaxnm generation in aarch64
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Indu Bhagat <indu dot bhagat at oracle dot com>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Tue, 8 May 2018 21:22:26 +0000
- Subject: Re: fminnm/fmaxnm generation in aarch64
- References: <4067c389-edc1-3858-e52c-8b9f167316a7@oracle.com> <7b6269f0-2daa-4335-e854-2685313da9c7@oracle.com>
On Mon, 7 May 2018, Indu Bhagat wrote:
> Q2. If one wants the compiler to generate fminnm/fmaxnm instructions, while
> conforming with IEEE standard, the way to do that will be to use math
> builtins fmin()/fmax(). Is this correct understanding?
For IEEE 754-2008 minNum / maxNum operations, which those instructions
correspond to and fmin and fmax bind to, yes. For IEEE 754-2018 (in
progress), there are different minimum / maximum operations, which don't
match those AArch64 instructions (but some do match RISC-V instructions),
and there are new proposed corresponding C functions such as fmaximum and
fminimum_num (I don't know of implementations of those functions).
--
Joseph S. Myers
joseph@codesourcery.com