Re: [AArch64] Enable generation of FRINTNZ instructions

[Richard Biener <rguenther@suse.de>]

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On Tue, 15 Nov 2022, Richard Sandiford wrote:

> "Andre Vieira (lists)" <andre.simoesdiasvieira@arm.com> writes:
> > On 07/11/2022 11:05, Richard Biener wrote:
> >> On Fri, 4 Nov 2022, Andre Vieira (lists) wrote:
> >>
> >>> Sorry for the delay, just been reminded I still had this patch outstanding
> >>> from last stage 1. Hopefully since it has been mostly reviewed it could go in
> >>> for this stage 1?
> >>>
> >>> I addressed the comments and gave the slp-part of vectorizable_call some TLC
> >>> to make it work.
> >>>
> >>> I also changed vect_get_slp_defs as I noticed that the call from
> >>> vectorizable_call was creating an auto_vec with 'nargs' that might be less
> >>> than the number of children in the slp_node
> >> how so?  Please fix that in the caller.  It looks like it probably
> >> shoud use vect_nargs instead?
> > Well that was my first intuition, but when I looked at it further the 
> > variant it's calling:
> > void vect_get_slp_defs (vec_info *, slp_tree slp_node, vec<vec<tree> > 
> > *vec_oprnds, unsigned n)
> >
> > Is actually creating a vector of vectors of slp defs. So for each child 
> > of slp_node it calls:
> > void vect_get_slp_defs (slp_tree slp_node, vec<tree> *vec_defs)
> >
> > Which returns a vector of vectorized defs. So vect_nargs would be the 
> > right size for the inner vec<tree> of vec_defs, but the outer should 
> > have the same number of elements as the original slp_node has children.
> >
> > However, at the call site (vectorizable_call), the operand we pass to 
> > vect_get_slp_defs 'vec_defs', is initialized before the code-path is 
> > specialized for slp_node. I'll go see if I can change the call site to 
> > not have to do that, given the continue at the end of the if (slp_node) 
> > BB I don't think it needs to use vec_defs after it, but it may require 
> > some massaging to be able to define it separately for each code-path.
> >
> >>
> >>> , so that quick_push might not be
> >>> safe as is, so I added the reserve (n) to ensure it's safe to push. I didn't
> >>> actually come across any failure because of it though. Happy to split this
> >>> into a separate patch if needed.
> >>>
> >>> Bootstrapped and regression tested on aarch64-none-linux-gnu and
> >>> x86_64-pc-linux-gnu.
> >>>
> >>> OK for trunk?
> >> I'll leave final approval to Richard but
> >>
> >> -     This only needs 1 bit, but occupies the full 16 to ensure a nice
> >> +     This only needs 1 bit, but occupies the full 15 to ensure a nice
> >>        layout.  */
> >>     unsigned int vectorizable : 16;
> >>
> >> you don't actually change the width of the bitfield.  I would find
> >> it more natural to have
> >>
> >>    signed int type0 : 7;
> >>    signed int type0_vtrans : 1;
> >>    signed int type1 : 7;
> >>    signed int type1_vtrans : 1;
> >>
> >> with typeN_vtrans specifying how the types transform when vectorized.
> >> I would imagine another variant we could need is narrow/widen
> >> according to either result or other argument type?  That said,
> >> just your flag would then be
> >>
> >>    signed int type0 : 7;
> >>    signed int pad   : 1;
> >>    signed int type1 : 7;
> >>    signed int type1_vect_as_scalar : 1;
> >>
> >> ?
> > That's a cool idea! I'll leave it as a single bit for now like that, if 
> > we want to re-use it for multiple transformations we will obviously need 
> > to rename & give it more bits.
> 
> I think we should steal bits from vectorizable rather than shrink
> type0 and type1 though.  Then add a 14-bit padding field to show
> how many bits are left.
> 
> > @@ -3340,9 +3364,20 @@ vectorizable_call (vec_info *vinfo,
> >        rhs_type = unsigned_type_node;
> >      }
> > 
> > +  /* The argument that is not of the same type as the others.  */
> >    int mask_opno = -1;
> > +  int scalar_opno = -1;
> >    if (internal_fn_p (cfn))
> > -    mask_opno = internal_fn_mask_index (as_internal_fn (cfn));
> > +    {
> > +      internal_fn ifn = as_internal_fn (cfn);
> > +      if (direct_internal_fn_p (ifn)
> > +	  && direct_internal_fn (ifn).type1_is_scalar_p)
> > +	scalar_opno = direct_internal_fn (ifn).type1;
> > +      else
> > +	/* For masked operations this represents the argument that carries the
> > +	   mask.  */
> > +	mask_opno = internal_fn_mask_index (as_internal_fn (cfn));
> 
> This doesn't seem logically like an else.  We should do both.
> 
> LGTM otherwise for the bits outside match.pd.  If Richard's happy with
> the match.pd bits then I think the patch is OK with those changes and
> without the vect_get_slp_defs thing (as you mentioned downthread).

Yes, the match.pd part looked OK.

> Thanks,
> Richard
> 
> 
> >>
> >>> gcc/ChangeLog:
> >>>
> >>>          * config/aarch64/aarch64.md (ftrunc<mode><frintnz_mode>2): New
> >>> pattern.
> >>>          * config/aarch64/iterators.md (FRINTNZ): New iterator.
> >>>          (frintnz_mode): New int attribute.
> >>>          (VSFDF): Make iterator conditional.
> >>>          * internal-fn.def (FTRUNC_INT): New IFN.
> >>>          * internal-fn.cc (ftrunc_int_direct): New define.
> >>>          (expand_ftrunc_int_optab_fn): New custom expander.
> >>>          (direct_ftrunc_int_optab_supported_p): New supported_p.
> >>>          * internal-fn.h (direct_internal_fn_info): Add new member
> >>>          type1_is_scalar_p.
> >>>          * match.pd: Add to the existing TRUNC pattern match.
> >>>          * optabs.def (ftrunc_int): New entry.
> >>>          * stor-layout.h (element_precision): Moved from here...
> >>>          * tree.h (element_precision): ... to here.
> >>>          (element_type): New declaration.
> >>>          * tree.cc (element_type): New function.
> >>>          (element_precision): Changed to use element_type.
> >>>          * tree-vect-stmts.cc (vectorizable_internal_function): Add
> >>> support for
> >>>          IFNs with different input types.
> >>>          (vect_get_scalar_oprnds): New function.
> >>>          (vectorizable_call): Teach to handle IFN_FTRUNC_INT.
> >>>          * tree-vect-slp.cc (check_scalar_arg_ok): New function.
> >>>          (vect_slp_analyze_node_operations): Use check_scalar_arg_ok.
> >>>          (vect_get_slp_defs): Ensure vec_oprnds has enough slots to push.
> >>>          * doc/md.texi: New entry for ftrunc pattern name.
> >>>          * doc/sourcebuild.texi (aarch64_frintzx_ok): New target.
> >>>
> >>> gcc/testsuite/ChangeLog:
> >>>
> >>>          * gcc.target/aarch64/merge_trunc1.c: Adapted to skip if frintnz
> >>> instructions available.
> >>>          * lib/target-supports.exp: Added aarch64_frintnzx_ok target and
> >>> aarch64_frintz options.
> >>>          * gcc.target/aarch64/frintnz.c: New test.
> >>>          * gcc.target/aarch64/frintnz_vec.c: New test.
> >>>          * gcc.target/aarch64/frintnz_slp.c: New test.
> >>>
> 

-- 
Richard Biener <rguenther@suse.de>
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