Re: [gentoo-dev] Review: desc/cpu_flags_x86.desc

[Matt Turner]

On Sun, Jan 18, 2015 at 3:23 PM, Michał Górny <mgorny@g.o> wrote:
> Dnia 2015-01-18, o godz. 15:15:22
> Matt Turner <mattst88@g.o> napisał(a):
>
>> On Sun, Jan 18, 2015 at 12:44 PM, Michał Górny <mgorny@g.o> wrote:
>> > Hello,
>> >
>> > I would like to commit the following flags as cpu_flags_x86_desc.
>> > The list combines global USE flags with some local USE flags I've been
>> > able to find.
>> >
>> >
>> > 3dnow - Use the 3DNow! instruction set
>> > 3dnowext - Use the Enhanced 3DNow! instruction set
>> > aes-ni - Enable support for Intel's AES instruction set (aes in cpuinfo)
>> > avx - Adds support for Advanced Vector Extensions instructions
>> > avx2 - Adds support for Advanced Vector Extensions 2 instructions
>> > fma - Use the Fused Multiply Add instruction set
>>
>> There are fma3 and fma4 instruction sets. We need to determine which
>> one the packages that have this flag are actually using and name the
>> flag appropriately.
>
> Ok then:
>
> fma3 - Use the Fused Multiply Add v3 instruction set
> fma4 - Use the Fused Multiply Add v4 instruction set

They're not actually versions 3 and 4, like SSE. The number is the
number of arguments the instructions take.

I'd just remove the 'v' from the description and call it good.

See http://en.wikipedia.org/wiki/FMA_instruction_set for more information.