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Re: [x86-64 psABI]: Extend x86-64 psABI to support AVX-512
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, GNU C Library <libc-alpha at sourceware dot org>, GCC Development <gcc at gcc dot gnu dot org>, Binutils <binutils at sourceware dot org>, "Girkar, Milind" <milind dot girkar at intel dot com>, "Kreitzer, David L" <david dot l dot kreitzer at intel dot com>
- Date: Wed, 24 Jul 2013 20:13:55 +0200
- Subject: Re: [x86-64 psABI]: Extend x86-64 psABI to support AVX-512
- References: <CAMe9rOrvMxSLj3LcYBs71tVdw6C0vJFKD2HxvnoHc13UamftwA at mail dot gmail dot com> <ddab98c2-bb3b-4d02-b403-e7d5690cfe00 at email dot android dot com> <CAMe9rOpxErCVtE-PDZ3Yb9mL+4E+XQ-are9Df4YBbEioj+MmZA at mail dot gmail dot com> <b9c5d467-834a-4b57-b48c-ac4bb450c9e5 at email dot android dot com>
On Wed, Jul 24, 2013 at 07:36:31PM +0200, Richard Biener wrote:
> "H.J. Lu" <hjl.tools@gmail.com> wrote:
>
> >On Wed, Jul 24, 2013 at 8:23 AM, Richard Biener
> ><richard.guenther@gmail.com> wrote:
> >> "H.J. Lu" <hjl.tools@gmail.com> wrote:
> >>
> >>>Hi,
> >>>
> >>>Here is a patch to extend x86-64 psABI to support AVX-512:
> >>
> >> Afaik avx 512 doubles the amount of xmm registers. Can we get them
> >callee saved please?
> >>
> >
> >Make them callee saved means we need to change ld.so to
> >preserve them and we need to change unwind library to
> >support them. It is certainly doable.
>
> IMHO it was a mistake to not have any callee saved xmm register in the original abi - we should fix this at this opportunity. Loops with function calls are not that uncommon.
>
I also noticed this problem and best solution that I came upon is analogue to
__attribute__((fastcall))
This would make possible for libraries to add versioned symbols that use
attribute and migrate to saner calling convention.
> Richard.
>
> >--
> >H.J.
>