RE: [RFC, vectorizer] Allow single element vector types for vector reduction operations

[Tamar Christina <Tamar dot Christina at arm dot com>]

> -----Original Message-----
> From: Richard Biener [mailto:rguenther@suse.de]
> Sent: 05 September 2017 14:13
> To: Tamar Christina
> Cc: Andrew Pinski; Andreas Schwab; Jon Beniston; gcc-patches@gcc.gnu.org;
> nd
> Subject: RE: [RFC, vectorizer] Allow single element vector types for vector
> reduction operations
> 
> On Tue, 5 Sep 2017, Tamar Christina wrote:
> 
> >
> >
> > > -----Original Message-----
> > > From: Richard Biener [mailto:rguenther@suse.de]
> > > Sent: 05 September 2017 13:51
> > > To: Tamar Christina
> > > Cc: Andrew Pinski; Andreas Schwab; Jon Beniston;
> > > gcc-patches@gcc.gnu.org; nd
> > > Subject: RE: [RFC, vectorizer] Allow single element vector types for
> > > vector reduction operations
> > >
> > > On Tue, 5 Sep 2017, Richard Biener wrote:
> > >
> > > > On Tue, 5 Sep 2017, Tamar Christina wrote:
> > > >
> > > > > Hi Richard,
> > > > >
> > > > > That was an really interesting analysis, thanks for the details!
> > > > >
> > > > > Would you be submitting the patch you proposed at the end as a fix?
> > > >
> > > > I'm testing it currently.
> > >
> > > Unfortunately it breaks some required lowering.  I'll have to more
> > > closely look at this.
> >
> > Ah, ok. In the meantime, can this patch be reverted? It's currently
> > breaking spec for us so we're Not able to get any benchmarking numbers.
> 
> Testing the following instead:

That does seem to build spec again, haven't tested the testsuite yet. 

> Index: gcc/tree-vect-generic.c
> ==========================================================
> =========
> --- gcc/tree-vect-generic.c     (revision 251642)
> +++ gcc/tree-vect-generic.c     (working copy)
> @@ -1640,7 +1640,7 @@ expand_vector_operations_1 (gimple_stmt_
>        || code == VEC_UNPACK_FLOAT_LO_EXPR)
>      type = TREE_TYPE (rhs1);
> 
> -  /* For widening/narrowing vector operations, the relevant type is of the
> +  /* For widening vector operations, the relevant type is of the
>       arguments, not the widened result.  VEC_UNPACK_FLOAT_*_EXPR is
>       calculated in the same way above.  */
>    if (code == WIDEN_SUM_EXPR
> @@ -1650,9 +1650,6 @@ expand_vector_operations_1 (gimple_stmt_
>        || code == VEC_WIDEN_MULT_ODD_EXPR
>        || code == VEC_UNPACK_HI_EXPR
>        || code == VEC_UNPACK_LO_EXPR
> -      || code == VEC_PACK_TRUNC_EXPR
> -      || code == VEC_PACK_SAT_EXPR
> -      || code == VEC_PACK_FIX_TRUNC_EXPR
>        || code == VEC_WIDEN_LSHIFT_HI_EXPR
>        || code == VEC_WIDEN_LSHIFT_LO_EXPR)
>      type = TREE_TYPE (rhs1);
> 
> 
> also fix for a bug uncovered by the previous one:
> 
> Index: gcc/gimple-ssa-strength-reduction.c
> ==========================================================
> =========
> --- gcc/gimple-ssa-strength-reduction.c (revision 251710)
> +++ gcc/gimple-ssa-strength-reduction.c (working copy)
> @@ -1742,8 +1742,7 @@ find_candidates_dom_walker::before_dom_c
>         slsr_process_ref (gs);
> 
>        else if (is_gimple_assign (gs)
> -              && SCALAR_INT_MODE_P
> -                   (TYPE_MODE (TREE_TYPE (gimple_assign_lhs (gs)))))
> +              && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (gs))))
>         {
>           tree rhs1 = NULL_TREE, rhs2 = NULL_TREE;
>