Re: [PATCH] middle-end/114189 - drop uses of vcond{,u,eq}_optab

[Richard Biener <rguenther@suse.de>]

On Fri, 14 Jun 2024, Richard Sandiford wrote:

> Richard Biener <rguenther@suse.de> writes:
> > The following retires vcond{,u,eq} optabs by stopping to use them
> > from the middle-end.  Targets instead (should) implement vcond_mask
> > and vec_cmp{,u,eq} optabs.  The PR this change refers to lists
> > possibly affected targets - those implementing these patterns,
> > and in particular it lists mips, sparc and ia64 as targets that
> > most definitely will regress while others might simply remove
> > their vcond{,u,eq} patterns.
> >
> > I'd appreciate testing, I do not expect fallout for x86 or arm/aarch64.
> > I know riscv doesn't implement any of the legacy optabs.  But less
> > maintained vector targets might need adjustments.
> >
> > I want to get rid of those optabs for GCC 15.  If I don't hear from
> > you I will assume your target is fine.
> 
> Great!  Thanks for doing this.
> 
> Is there a plan for how we should handle vector comparisons that
> have to be done as the inverse of the negated condition?  Should
> targets simply not provide vec_cmp for such conditions and leave
> the target-independent code to deal with the fallout?  (For a
> standalone comparison, it would invert the result.  For a VEC_COND_EXPR
> it would swap the true and false values.)

I would expect that the ISEL pass which currently deals with finding
valid combos of .VCMP{,U,EQ} and .VCOND_MASK deals with this.
So how do we deal with this right now?  I expect RTL expansion will
do the inverse trick, no?

Thanks,
Richard.

> Richard
> 
> >
> > Thanks,
> > Richard.
> >
> > 	PR middle-end/114189
> > 	* optabs-query.h (get_vcond_icode): Always return CODE_FOR_nothing.
> > 	(get_vcond_eq_icode): Likewise.
> > ---
> >  gcc/optabs-query.h | 13 ++++---------
> >  1 file changed, 4 insertions(+), 9 deletions(-)
> >
> > diff --git a/gcc/optabs-query.h b/gcc/optabs-query.h
> > index 0cb2c21ba85..31fbce80175 100644
> > --- a/gcc/optabs-query.h
> > +++ b/gcc/optabs-query.h
> > @@ -112,14 +112,9 @@ get_vec_cmp_eq_icode (machine_mode vmode, machine_mode mask_mode)
> >     mode CMODE, unsigned if UNS is true, resulting in a value of mode VMODE.  */
> >  
> >  inline enum insn_code
> > -get_vcond_icode (machine_mode vmode, machine_mode cmode, bool uns)
> > +get_vcond_icode (machine_mode, machine_mode, bool)
> >  {
> > -  enum insn_code icode = CODE_FOR_nothing;
> > -  if (uns)
> > -    icode = convert_optab_handler (vcondu_optab, vmode, cmode);
> > -  else
> > -    icode = convert_optab_handler (vcond_optab, vmode, cmode);
> > -  return icode;
> > +  return CODE_FOR_nothing;
> >  }
> >  
> >  /* Return insn code for a conditional operator with a mask mode
> > @@ -135,9 +130,9 @@ get_vcond_mask_icode (machine_mode vmode, machine_mode mmode)
> >     mode CMODE (only EQ/NE), resulting in a value of mode VMODE.  */
> >  
> >  inline enum insn_code
> > -get_vcond_eq_icode (machine_mode vmode, machine_mode cmode)
> > +get_vcond_eq_icode (machine_mode, machine_mode)
> >  {
> > -  return convert_optab_handler (vcondeq_optab, vmode, cmode);
> > +  return CODE_FOR_nothing;
> >  }
> >  
> >  /* Enumerates the possible extraction_insn operations.  */
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)