[Bug rtl-optimization/31485] C complex numbers, amd64 SSE, missed optimization opportunity

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31485

--- Comment #22 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 21 Apr 2020, jakub at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31485
> 
> Jakub Jelinek <jakub at gcc dot gnu.org> changed:
> 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>                  CC|                            |hjl.tools at gmail dot com,
>                    |                            |hubicka at gcc dot gnu.org,
>                    |                            |matz at gcc dot gnu.org
> 
> --- Comment #19 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
> CCing Micha and Honza on the ABI question.

The arguments are class SSE (__m64), but I fail to find clarification
as to whether "unused" parts of argument registers (the SSEUP part
of the %xmmN register) is supposed to be zeroed or has unspecified
contents.