On Fri, 8 Jul 2022, Tamar Christina wrote:
> > -----Original Message-----
> > From: Richard Biener <rguent...@suse.de>
> > Sent: Thursday, July 7, 2022 8:47 AM
> > To: Tamar Christina <tamar.christ...@arm.com>
> > Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>
> > Subject: RE: [PATCH]middle-end: don't lower past veclower [PR106063]
> >
> > On Thu, 7 Jul 2022, Tamar Christina wrote:
> >
> > > > -----Original Message-----
> > > > From: Richard Biener <rguent...@suse.de>
> > > > Sent: Thursday, July 7, 2022 8:19 AM
> > > > To: Tamar Christina <tamar.christ...@arm.com>
> > > > Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>
> > > > Subject: Re: [PATCH]middle-end: don't lower past veclower [PR106063]
> > > >
> > > > On Tue, 5 Jul 2022, Tamar Christina wrote:
> > > >
> > > > > Hi All,
> > > > >
> > > > > My previous patch can cause a problem if the pattern matches after
> > > > > veclower as it may replace the construct with a vector sequence
> > > > > which the target may not directly support.
> > > > >
> > > > > As such don't perform the rewriting if after veclower.
> > > >
> > > > Note that when doing the rewriting before veclower to a variant not
> > > > supported by the target can cause veclower to generate absymal code.
> > > > In some cases we are very careful and try to at least preserve code
> > > > supported by the target over transforming that into a variant not
> > supported.
> > > >
> > > > That said, a better fix would be to check whether the target can
> > > > perform the new comparison. Before veclower it would be OK to do
> > > > the transform nevertheless in case it cannot do the original transform.
> > >
> > > This last statement is somewhat confusing. Did you want me to change
> > > it such that before veclower the rewrite is always done and after
> > > veclowering only if the target supports it?
> > >
> > > Or did you want me to never do the rewrite if the target doesn't support
> > > it?
> >
> > I meant before veclower you can do the rewrite if either the rewriting
> > result
> > is supported by the target OR if the original expression is _not_ supported
> > by
> > the target. The latter case might be not too important to worry doing (it
> > would still canonicalize for those targets then). After veclower you can
> > only
> > rewrite under the former condition.
> >
>
> Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
> and no issues.
>
> Ok for master? and backport to GCC 12?
OK for master, backport to GCC 12 after a few days of soaking.
Thanks,
Richard.
> Thanks,
> Tamar
>
>
> gcc/ChangeLog:
>
> PR tree-optimization/106063
> * match.pd: Only rewrite if target support it.
>
> gcc/testsuite/ChangeLog:
>
> PR tree-optimization/106063
> * gcc.dg/pr106063.c: New test.
>
> --- inline copy of patch ---
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index
> 40c09bedadb89dabb6622559a8f69df5384e61fd..5800a105c3cdada9d5e1d8019176ebbe5969ccb0
> 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -6041,10 +6041,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (cmp (bit_and:c@2 @0 cst@1) integer_zerop)
> (with { tree csts = bitmask_inv_cst_vector_p (@1); }
> (if (csts && (VECTOR_TYPE_P (TREE_TYPE (@1)) || single_use (@2)))
> - (if (TYPE_UNSIGNED (TREE_TYPE (@1)))
> - (icmp @0 { csts; })
> - (with { tree utype = unsigned_type_for (TREE_TYPE (@1)); }
> - (icmp (view_convert:utype @0) { csts; }))))))))
> + (with { auto optab = VECTOR_TYPE_P (TREE_TYPE (@1))
> + ? optab_vector : optab_default;
> + tree utype = unsigned_type_for (TREE_TYPE (@1)); }
> + (if (target_supports_op_p (utype, icmp, optab)
> + || (optimize_vectors_before_lowering_p ()
> + && (!target_supports_op_p (type, cmp, optab)
> + || !target_supports_op_p (type, BIT_AND_EXPR, optab))))
> + (if (TYPE_UNSIGNED (TREE_TYPE (@1)))
> + (icmp @0 { csts; })
> + (icmp (view_convert:utype @0) { csts; })))))))))
>
> /* When one argument is a constant, overflow detection can be simplified.
> Currently restricted to single use so as not to interfere too much with
> diff --git a/gcc/testsuite/gcc.dg/pr106063.c b/gcc/testsuite/gcc.dg/pr106063.c
> new file mode 100644
> index
> 0000000000000000000000000000000000000000..b23596724f6bb98c53af2dce77d31509bab10378
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr106063.c
> @@ -0,0 +1,9 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fno-tree-forwprop --disable-tree-evrp" } */
> +typedef __int128 __attribute__((__vector_size__ (16))) V;
> +
> +V
> +foo (V v)
> +{
> + return (v & (V){15}) == v;
> +}
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstra
