Re: [PATCH 2/4 v2][AArch64] Add support for FCCMP

[Evandro Menezes <e dot menezes at samsung dot com>]

On 01/21/16 16:55, Evandro Menezes wrote:
> On 01/21/16 16:07, James Greenhalgh wrote:
> > On Thu, Jan 21, 2016 at 01:58:31PM -0600, Evandro Menezes wrote:
> > > Hi, James.
> > >
> > > On 01/21/16 03:24, James Greenhalgh wrote:
> > > > On Wed, Jan 06, 2016 at 02:44:47PM -0600, Evandro Menezes wrote:
> > > > > On 01/06/2016 06:04 AM, Wilco Dijkstra wrote:
> > > > > > > Here's what I had in mind when I inquired about distinguishing 
> > > > > > > FCMP from
> > > > > > > FCCMP.  As you can see in the patch, Exynos is the only target that
> > > > > > > cares about it, but I wonder if ThunderX or Xgene would too.
> > > > > > >
> > > > > > > What do you think?
> > > > > > The new attributes look fine (I've got a similar outstanding 
> > > > > > change), however
> > > > > > please don't add them to non-AArch64 cores. We only need it for 
> > > > > > thunderx.md,
> > > > > > cortex-a53.md, cortex-a57.md, xgene1.md and exynos-m1.md.
> > > > >          Add support for the FCCMP insn types
> > > > >
> > > > >          2016-01-04  Evandro Menezes <e.menezes@samsung.com>
> > > > >
> > > > >          gcc/
> > > > >              * config/aarch64/aarch64.md (fccmp): Change insn type.
> > > > >              (fccmpe): Likewise.
> > > > >              * config/aarch64/thunderx.md (thunderx_fcmp): Add
> > > > >     "fccmp{s,d}" types.
> > > > >              * config/arm/cortex-a53.md (cortex_a53_fpalu): Likewise.
> > > > >              * config/arm/cortex-a57.md (cortex_a57_fp_cmp): 
> > > > > Likewise.
> > > > >              * config/arm/xgene1.md (xgene1_fcmp): Likewise.
> > > > >              * config/arm/exynos-m1.md (exynos_m1_fp_ccmp): New insn
> > > > >     reservation.
> > > > >              * config/arm/types.md (fccmps): Add new insn type.
> > > > >              (fccmpd): Likewise.
> > > > >
> > > > > Got it.  Here's an updated patch.  Again, assuming that your
> > > > > original patch is in place.  Perhaps you can build on it.
> > > > If we don't have any targets which care about the fccmps/fccmpd 
> > > > split in
> > > > the code base, do we really need it? Can we just follow the example of
> > > > fcsel?
> > > The Exynos M1 does care about the difference between FCMP and FCCMP,
> > > as can be seen in the patch.
> > > More explicitly:
> > >
> > >     (define_insn_reservation "exynos_m1_fp_cmp" 4
> > >        (and (eq_attr "tune" "exynosm1")
> > >             (eq_attr "type" "fcmps, fcmpd"))
> > >        "em1_nmisc")
> > >
> > >     (define_insn_reservation "exynos_m1_fp_ccmp" 7
> > >        (and (eq_attr "tune" "exynosm1")
> > >             (eq_attr "type" "fccmps, fccmpd"))
> > >        "em1_st, em1_nmisc")
> > I think I was unclear. Your exynos-m1 model cares about splitting 
> > fcmp[s/d]
> > and fccmp, but it doesn't care about splitting fccmp in to 
> > fccmps/fccmpd. It
> > is the split to fccmps/fccmpd that I think is unneccesary at this time.
>
> Indeed.  However, it seems to me that the jury is still out about the 
> {s,d} suffix, isn't it?  Otherwise, whatever others deem better.  I 
> myself am agnostic about it.
>
> > > > > diff --git a/gcc/config/arm/types.md b/gcc/config/arm/types.md
> > > > > index 321ff89..daf7162 100644
> > > > > --- a/gcc/config/arm/types.md
> > > > > +++ b/gcc/config/arm/types.md
> > > > > @@ -70,6 +70,7 @@
> > > > >   ; f_rint[d,s]        double/single floating point rount to 
> > > > > integral.
> > > > >   ; f_store[d,s]       double/single store to memory. Used for VFP 
> > > > > unit.
> > > > >   ; fadd[d,s]          double/single floating-point scalar addition.
> > > > > +; fccmp[d,s]         double/single floating-point conditional 
> > > > > compare.
> > > > Can we follow the convention fcsel uses of calling out "From ARMv8-A:"
> > > > for this type?
> > > I'm not sure I follow.  Though I didn't refer to the ISA spec, I
> > > used the description from it for the *fccmp* type.
> > Something like:
> >
> > ; fccmp    From ARMv8-A: floating point conditional compare.
> >
> > Just to capture that this instruction is only available for cores 
> > implementing
> > ARMv8-A.
>
>
> Got it.
>
> Let me try this again:
>
>    Add support for the FCCMP insn types
>
>    2016-01-21  Evandro Menezes  <e.menezes@samsung.com>
>
>    gcc/
>             * config/aarch64/aarch64.md (fccmp): Change insn type.
>             (fccmpe): Likewise.
>             * config/aarch64/thunderx.md (thunderx_fcmp): Add
>    "fccmp{s,d}" types.
>             * config/arm/cortex-a53.md (cortex_a53_fpalu): Likewise.
>             * config/arm/cortex-a57.md (cortex_a57_fp_cmp): Likewise.
>             * config/arm/xgene1.md (xgene1_fcmp): Likewise.
>             * config/arm/exynos-m1.md (exynos_m1_fp_ccmp): New insn
>    reservation.
>             * config/arm/types.md (fccmps): Add new insn type.
>             (fccmpd): Likewise.

*Ping*

--
Evandro Menezes