[Mesa-dev] [PATCH] ac/nir: use llvm fma intrinsic if nir instruction is exact.

[Marek Olšák]

On Fri, Oct 6, 2017 at 4:10 AM, Connor Abbott <cwabbott0 at gmail.com> wrote:
> On Thu, Oct 5, 2017 at 10:08 PM, Marek Olšák <maraeo at gmail.com> wrote:
>> On Fri, Oct 6, 2017 at 3:50 AM, Connor Abbott <cwabbott0 at gmail.com> wrote:
>>> Why? While it might technically be legal, always generating an unfused
>>> mul+add when the user explicitly requested fma() seems harsh...
>>
>> It's slow on some chips. It doesn't need any other reason.
>>
>> Marek
>
> Presumably, if the developer asked for fma, then they don't care how
> fast or slow it is...

Feral asked for fma. They care. This debate is pointless. We just
won't use fma by default. Period.

Marek