> -----Original Message-----
> From: Richard Sandiford <richard.sandiford@arm.com>
> Sent: Tuesday, November 15, 2022 11:59 AM
> To: Tamar Christina via Gcc-patches <gcc-patches@gcc.gnu.org>
> Cc: Tamar Christina <Tamar.Christina@arm.com>; nd <nd@arm.com>;
> rguenther@suse.de; jlaw@ventanamicro.com
> Subject: Re: [PATCH]middle-end: replace GET_MODE_WIDER_MODE with
> GET_MODE_NEXT_MODE
> 
> Tamar Christina via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
> > Hi All,
> >
> > After the fix to the addsub patch yesterday for bootstrap I had only
> regtested on x86.
> > While looking today it seemed the new tests were failing, this was
> > caused by a change in the behavior of the GET_MODE_WIDER_MODE
> macro on trunk.
> >
> > This patch fixes that issue. Sorry for the mess, have rebased all branches
> now.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
> >
> > Ok for master?
> >
> > Thanks,
> > Tamar
> >
> > gcc/ChangeLog:
> >
> > 	* match.pd: Replace GET_MODE_WIDER_MODE with
> > 	GET_MODE_NEXT_MODE.
> >
> > --- inline copy of patch --
> > diff --git a/gcc/match.pd b/gcc/match.pd index
> >
> 1b0ab7cf60fa4772fbe8304c622b0b8fab1bdefa..28191a992039c6f3a1dab5f7c0
> e3
> > 5dd58dc47092 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -7997,7 +7997,7 @@ and,
> >         machine_mode wide_mode;
> >       }
> >       (if (sel.series_p (0, 2, 0, 2)
> > -          && GET_MODE_WIDER_MODE (vec_mode).exists (&wide_mode)
> > +          && GET_MODE_NEXT_MODE (vec_mode).exists (&wide_mode)
> >  	  && VECTOR_MODE_P (wide_mode)
> >  	  && (GET_MODE_UNIT_BITSIZE (vec_mode) * 2
> >  	      == GET_MODE_UNIT_BITSIZE (wide_mode)))
> 
> Does anything guarantee that the next mode will be the right one?
> It think it would be safer to replace the last three && conditions with:
> 
>    && GET_MODE_2XWIDER_MODE (GET_MODE_INNER (vec_mode)).exists
> (&wide_elt_mode)
>    && multiple_p (GET_MODE_NUNITS (vec_mode), 2, &wide_nunits)
>    && related_vector_mode (vec_mode, wide_elt_mode,
> 			   wide_nunits).exists (&wide_mode)

I see, respun patch accordingly.

Ok for master?

--- inline copy of patch ---

diff --git a/gcc/match.pd b/gcc/match.pd
index 1b0ab7cf60fa4772fbe8304c622b0b8fab1bdefa..82f05bbc912e4f80f3984d930c4a8dcb010136e1 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7995,12 +7995,15 @@ and,
        vec_perm_indices sel (builder, 2, nelts);
        machine_mode vec_mode = TYPE_MODE (type);
        machine_mode wide_mode;
+       scalar_mode wide_elt_mode;
+       poly_uint64 wide_nunits;
+       scalar_mode inner_mode = GET_MODE_INNER (vec_mode);
      }
      (if (sel.series_p (0, 2, 0, 2)
-          && GET_MODE_WIDER_MODE (vec_mode).exists (&wide_mode)
-	  && VECTOR_MODE_P (wide_mode)
-	  && (GET_MODE_UNIT_BITSIZE (vec_mode) * 2
-	      == GET_MODE_UNIT_BITSIZE (wide_mode)))
+	  && GET_MODE_2XWIDER_MODE (inner_mode).exists (&wide_elt_mode)
+	  && multiple_p (GET_MODE_NUNITS (vec_mode), 2, &wide_nunits)
+	  && related_vector_mode (vec_mode, wide_elt_mode,
+				  wide_nunits).exists (&wide_mode))
 	(with
 	 {
 	   tree stype