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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/68050] SLP vectorization should negate constants to match up + vs -
Date: Mon, 30 Aug 2021 07:44:05 +0000	[thread overview]
Message-ID: <bug-68050-4-IGWRtLm03n@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-68050-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68050

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
We don't really do it as you show - instead of

  vect__5.7_12 = vect__1.5_14 + { -3.0e+0, -3.0e+0 };
  vect__2.6_13 = vect__1.5_14 + { 3.0e+0, 3.0e+0 };
  _7 = VEC_PERM_EXPR <vect__2.6_13, vect__5.7_12, { 0, 3 }>;

we'd like to see

  _7 = vect__1.5_14 + { 3.0e+0, -3.0e+0 };

which is what we should cost as well.

      parent reply	other threads:[~2021-08-30  7:44 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-22 10:03 [Bug tree-optimization/68050] New: " rguenth at gcc dot gnu.org
2015-10-22 10:03 ` [Bug tree-optimization/68050] " rguenth at gcc dot gnu.org
2021-08-29  4:39 ` pinskia at gcc dot gnu.org
2021-08-30  7:44 ` rguenth at gcc dot gnu.org [this message]

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