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 CEB3D3858C2C; Wed, 22 Dec 2021 07:24:32 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CEB3D3858C2C
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/103798] memchr with a (small) constant string
 should be expanded inline.
Date: Wed, 22 Dec 2021 07:24:32 +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: 11.2.1
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: pinskia 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 everconfirmed bug_status bug_severity
 short_desc cf_reconfirmed_on
Message-ID: <bug-103798-4-SiL855cfcx@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-103798-4@http.gcc.gnu.org/bugzilla/>
References: <bug-103798-4@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: Wed, 22 Dec 2021 07:24:32 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103798

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|libstdc++                   |tree-optimization
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
           Severity|normal                      |enhancement
            Summary|Missed optimization:        |memchr with a (small)
                   |char_traits<char>::find     |constant string should be
                   |(and thus                   |expanded inline.
                   |string_view::find_first_of) |
                   |is slow when invoked with   |
                   |short strings               |
   Last reconfirmed|                            |2021-12-22

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Really the issue is:
  _8 =3D __builtin_memchr ("eE", _7, 2);
  if (_8 !=3D 0B)


Should just be expanded to _7 =3D=3D 'e' || _7 =3D=3D 'E' .

That is:
int f(char a)
{
   return  __builtin_memchr ("e", a, 1) !=3D 0;
}
int f1(char a)
{
   return a =3D=3D 'e';
}
int g(char a)
{
   return  __builtin_memchr ("eE", a, 2) !=3D 0;
}
int g1(char a)
{
   return a =3D=3D 'e' || a =3D=3D 'E';
}

f and f1 should produce the same assembly
and g and g1 should produce the same (similar) assembly.=