> -----Original Message----- > From: Jakub Jelinek <ja...@redhat.com> > Sent: Wednesday, November 16, 2022 3:38 PM > To: Richard Biener <richard.guent...@gmail.com> > Cc: Tamar Christina <tamar.christ...@arm.com>; Hongyu Wang > <wwwhhhyyy...@gmail.com>; Prathamesh Kulkarni > <prathamesh.kulka...@linaro.org>; Richard Sandiford > <richard.sandif...@arm.com>; Hongyu Wang <hongyu.w...@intel.com>; > hongtao....@intel.com; gcc-patches@gcc.gnu.org > Subject: Re: [PATCH] Optimize VEC_PERM_EXPR with same permutation > index and operation [PR98167] > > On Wed, Nov 16, 2022 at 04:30:06PM +0100, Richard Biener via Gcc-patches > wrote: > > On Wed, Nov 16, 2022 at 4:29 PM Richard Biener > > <richard.guent...@gmail.com> wrote: > > > > > > On Wed, Nov 16, 2022 at 4:25 PM Tamar Christina > <tamar.christ...@arm.com> wrote: > > > > > > > > Hi, > > > > > > > > This patch is causing several ICEs because it changes the permutes > > > > from a single register permute to a multi register due to the lowering > > > > of > the expressions to different SSA names. > > > > > > > > See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107717 > > > > > > > > I have a prototype fix which adds a new rule to CSE this back to a > > > > single register permute, but would this be the right solution? It > > > > seems hard to later on during expand realize that the two operands are > the same. > > > > > > > > It's probably also ok to just block this from happening after > > > > vec_lower, however I'm worried that If it wasn't CSE'd before > vec_lower it'll lower it so something much less efficient. > > > > > > You can use > > > > > > (vec_perm (op@7 @0 @1) @3) > > > > Err, (vec_perm (op@7 @0 @1) @7) obviously. > > Even: > > --- gcc/match.pd.jj 2022-11-15 07:56:05.240348804 +0100 > +++ gcc/match.pd 2022-11-16 16:35:34.854080956 +0100 > @@ -8259,7 +8259,7 @@ and, > (simplify > (op (vec_perm @0 @0 @2) (vec_perm @1 @1 @2)) > (if (VECTOR_INTEGER_TYPE_P (type)) > - (vec_perm (op @0 @1) (op @0 @1) @2)))) > + (vec_perm (op@3 @0 @1) @3 @2)))) > > /* Similar for float arithmetic when permutation constant covers > all vector elements. */ > @@ -8298,4 +8298,4 @@ and, > } > } > (if (full_perm_p) > - (vec_perm (op @0 @1) (op @0 @1) @2)))))) > + (vec_perm (op@3 @0 @1) @3 @2)))))) > > From quick look at the dumps, it seems to work fine. > > Jakub
Yes that's the patch I'm currently reg-testing 😊 Cheers, Tamar
