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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/52252] An opportunity for x86 gcc vectorizer (gain up to 3 times)
Date: Tue, 28 Nov 2023 22:24:56 +0000	[thread overview]
Message-ID: <bug-52252-4-ocXAu3CkkY@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-52252-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52252

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to rguenther@suse.de from comment #11)
> We're lacking a way to say one of the bit_not should be single-used,
> one multi-use would be OK and a fair trade-off - not sure if that
> would be enough here, of course.  That would mena changing to
> a condition with single_use ().

That does not fix it though. Because in this case we have:
  c_19 = ~r_16;
  m_20 = ~g_17;
  y_21 = ~b_18;
  tmp_22 = MIN_EXPR <m_20, y_21>;
  k_23 = MIN_EXPR <c_19, tmp_22>;
  _1 = c_19 - k_23;
  _3 = m_20 - k_23;
  _5 = y_21 - k_23;
  .. = k_23;

So both bit_not are used more than once.

so we have `~a - MIN<MIN<~a, ~b>, ~c>` which is the same as `MAX<MAX<a,b>,c> -
a`.

Let me file this as a seperate bug to continue the discussion there.

      parent reply	other threads:[~2023-11-28 22:24 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-14 22:42 [Bug c/52252] New: " evstupac at gmail dot com
2012-02-15 11:55 ` [Bug tree-optimization/52252] " rguenth at gcc dot gnu.org
2012-02-29 12:34 ` evstupac at gmail dot com
2012-07-13  8:48 ` rguenth at gcc dot gnu.org
2014-02-11 14:27 ` evstupac at gmail dot com
2014-05-07 12:11 ` kyukhin at gcc dot gnu.org
2014-06-11  8:38 ` kyukhin at gcc dot gnu.org
2014-06-18  7:47 ` kyukhin at gcc dot gnu.org
2023-08-31  7:07 ` rguenth at gcc dot gnu.org
2023-11-28  6:06 ` pinskia at gcc dot gnu.org
2023-11-28 10:55 ` rguenther at suse dot de
2023-11-28 22:24 ` pinskia at gcc dot gnu.org [this message]

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