On Thu, Aug 10, 2023 at 2:04 PM Uros Bizjak via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> On Thu, Aug 10, 2023 at 3:13 AM liuhongt <hongtao....@intel.com> wrote:
> >
> > Currently we have 3 different independent tunes for gather
> > "use_gather,use_gather_2parts,use_gather_4parts",
> > similar for scatter, there're
> > "use_scatter,use_scatter_2parts,use_scatter_4parts"
> >
> > The patch support 2 standardizing options to enable/disable
> > vectorization for all gather/scatter instructions. The options is
> > interpreted by driver to 3 tunes.
> >
> > bootstrapped and regtested on x86_64-pc-linux-gnu.
> > Ok for trunk?
> >
> > gcc/ChangeLog:
> >
> > * config/i386/i386.h (DRIVER_SELF_SPECS): Add
> > GATHER_SCATTER_DRIVER_SELF_SPECS.
> > (GATHER_SCATTER_DRIVER_SELF_SPECS): New macro.
> > * config/i386/i386.opt (mgather): New option.
> > (mscatter): Ditto.
> > ---
> > gcc/config/i386/i386.h | 12 +++++++++++-
> > gcc/config/i386/i386.opt | 8 ++++++++
> > 2 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
> > index ef342fcee9b..d9ac2c29bde 100644
> > --- a/gcc/config/i386/i386.h
> > +++ b/gcc/config/i386/i386.h
> > @@ -565,7 +565,17 @@ extern GTY(()) tree x86_mfence;
> > # define SUBTARGET_DRIVER_SELF_SPECS ""
> > #endif
> >
> > -#define DRIVER_SELF_SPECS SUBTARGET_DRIVER_SELF_SPECS
> > +#ifndef GATHER_SCATTER_DRIVER_SELF_SPECS
> > +# define GATHER_SCATTER_DRIVER_SELF_SPECS \
> > +
> > "%{mno-gather:-mtune-ctrl=^use_gather_2parts,^use_gather_4parts,^use_gather}
> > \
> > + %{mgather:-mtune-ctrl=use_gather_2parts,use_gather_4parts,use_gather} \
> > +
> > %{mno-scatter:-mtune-ctrl=^use_scatter_2parts,^use_scatter_4parts,^use_scatter}
> > \
> > +
> > %{mscatter:-mtune-ctrl=use_scatter_2parts,use_scatter_4parts,use_scatter}"
> > +#endif
> > +
> > +#define DRIVER_SELF_SPECS \
> > + SUBTARGET_DRIVER_SELF_SPECS " " \
> > + GATHER_SCATTER_DRIVER_SELF_SPECS
> >
> > /* -march=native handling only makes sense with compiler running on
> > an x86 or x86_64 chip. If changing this condition, also change
> > diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt
> > index ddb7f110aa2..99948644a8d 100644
> > --- a/gcc/config/i386/i386.opt
> > +++ b/gcc/config/i386/i386.opt
> > @@ -424,6 +424,14 @@ mdaz-ftz
> > Target
> > Set the FTZ and DAZ Flags.
> >
> > +mgather
> > +Target
> > +Enable vectorization for gather instruction.
> > +
> > +mscatter
> > +Target
> > +Enable vectorization for scatter instruction.
>
> Are gather and scatter instructions affected in a separate way, or
> should we use one -mgather-scatter option to cover all gather/scatter
> tunings?
A separate way.
Gather Data Sampling is only for gather.
https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/advisory-guidance/gather-data-sampling.html
>
> Uros.
>
> > +
> > mpreferred-stack-boundary=
> > Target RejectNegative Joined UInteger
> > Var(ix86_preferred_stack_boundary_arg)
> > Attempt to keep stack aligned to this power of 2.
> > --
> > 2.31.1
> >
--
BR,
Hongtao
