From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 94531396ECB1; Thu,  3 Dec 2020 11:24:27 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 94531396ECB1
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/97770] [ICELAKE]Missing vectorization for
 vpopcnt
Date: Thu, 03 Dec 2020 11:24:27 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: component
Message-ID: <bug-97770-4-rJ7xsUCAJE@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-97770-4@http.gcc.gnu.org/bugzilla/>
References: <bug-97770-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Thu, 03 Dec 2020 11:24:27 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97770

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|target                      |tree-optimization

--- Comment #14 from Richard Biener <rguenth at gcc dot gnu.org> ---
So we vectorize to

  _18 =3D .POPCOUNT (vect__5.7_22);
  _17 =3D .POPCOUNT (vect__5.7_21);
  vect__6.8_16 =3D VEC_PACK_TRUNC_EXPR <_18, _17>;
  _6 =3D 0;
  _7 =3D dest_13(D) + _2;
  vect__8.9_10 =3D [vec_unpack_lo_expr] vect__6.8_16;
  vect__8.9_9 =3D [vec_unpack_hi_expr] vect__6.8_16;
  _8 =3D (long long int) _6;

which is exactly the issue that in the scalar code we have a 'int' producing
popcount with long long argument but the vector IFN produces a result of the
same width as the argument.  So the vectorizer compensates for that
(VEC_PACK_TRUNC_EXPR) and then vectorizes the widening that's in the scalar
code (vec_unpack_{lo,hi}_expr).  The fix for this and for the missing
byte and word variants is to add a pattern to tree-vect-patterns.c for this
case matching it to the .POPCOUNT internal function.  That possibly applies
to other bitops, too, like parity, ctz, ffs, etc.  There's quite some
_widen helpers in the pattern recog code so I'm not sure how complicated
it is to match

 (long)popcountl(long)

and

 (short)popcount((int)short)

Richard may have a good idea since he did the last "big" surgery there.=