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RE: Should -mfma/-mavx and -msse5/-msse4a mutually exclusive?
- From: "rajagopal, dwarak" <dwarak dot rajagopal at amd dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>, "Uros Bizjak" <ubizjak at gmail dot com>, "GCC Development" <gcc at gcc dot gnu dot org>, "Ye, Joey" <joey dot ye at intel dot com>, "Guo, Xuepeng" <xuepeng dot guo at intel dot com>
- Date: Tue, 18 Nov 2008 16:13:13 -0600
- Subject: RE: Should -mfma/-mavx and -msse5/-msse4a mutually exclusive?
- References: <6dc9ffc80811161104n7ab08e7ega5e176320090b3b4@mail.gmail.com>
I think, Intel's FMA instructions are different from the FMA
instructions covered in -mfma (inside -msse5). I believe Intel's FMA
should be part of a separate switch.
> Also I am not sure if "-mavx -msse5" or "-mavx -msse4a" make any
senses. I
> think
> -mavx should turn off -msse5/-msse4a and vice versa.
>
Yes. We can have -mavx turn off -msse5/-msse4a.
Thanks,
Dwarak
> -----Original Message-----
> From: H.J. Lu [mailto:hjl.tools@gmail.com]
> Sent: Sunday, November 16, 2008 1:04 PM
> To: Uros Bizjak; GCC Development; Ye, Joey; Guo, Xuepeng; rajagopal,
> dwarak
> Subject: Should -mfma/-mavx and -msse5/-msse4a mutually exclusive?
>
> Hi,
>
> We are looking into Intel FMA support in gcc. For
>
> double
> foo (double x, double y, double z)
> {
> return x * y + z;
> }
>
> What should "-mfma -msse5" generate? Should -msse5 turn off -mfma and
> vice versa?
> Also I am not sure if "-mavx -msse5" or "-mavx -msse4a" make any
senses. I
> think
> -mavx should turn off -msse5/-msse4a and vice versa.
>
> Thanks.
>
> --
> H.J.