Re: [RFC PATCH v1 1/1] PPC64: Implement POWER Architecture Vector Function ABI.

[GT <tnggil@protonmail.com>]

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Thursday, August 13, 2020 5:00 PM, Jakub Jelinek <jakub@redhat.com> wrote:

> On Thu, Aug 13, 2020 at 08:40:22PM +0000, GT wrote:
>
> > I'm looking at ix86_simd_clone_adjust and also aarch64_simd_clone_adjust. The latter is
> > much simpler and I see how I would add PPC attribute "vsx" similarly. If I was to follow
> > the ix86_simd_clone_adjust organization, then ix86_valid_target_attribute_p called near
> > the end of the function is a problem. Because it in turn calls
> > ix86_valid_target_attribute_tree and this last function doesn't have a similarly named
> > function in PPC code.
> > Also, once the attribute "vsx" is added, where is it used? I mean that in the sense of
> > where is execution conditioned on the definition of say, the "sse2" string in x86_64?
>
> You need to trigger what will the middle-end and backend do if you use
> explicit attribute((target ("vsx"))) on the function, so in the end it
> needs to do some parsing, create a TARGET_OPTION_NODE with the right option
> changes and put it to the function.
>
> Jakub

I'm still trying to understand why we need attribute((target("vsx"))).

https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes

The documentation for target(string) states that the purpose is to allow a function to be
compiled with different target options than were specified on the command line. Why would we
want the vector version of say sinf to be compiled for a different target than the scalar sinf?

Bert.