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 4DFB4385E037; Wed, 27 Mar 2024 17:51:00 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 4DFB4385E037
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1711561860;
	bh=VQJ8pn6gkJNxHXGJJwQxCrLFUJbUMnJxiD7DoM2sQZo=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=YdHvl56fdSL+5uuMuKOZz135k8+jrqvUliZAtHvlfZOmSsnfyq2Ue4CRYdJa7TXWj
	 9U6OXheleNBGOKcCNKT+nwoRNWbEjPypPpkWd++bEq9+9BsYt4WBScpSTf2xLm/oGz
	 zUvnIlk6DkcrG9Cf8+kJFgb8Lp6hkakIAgqEDl0k=
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/93565] [11/12/13/14 regression] Combine
 duplicates instructions
Date: Wed, 27 Mar 2024 17:50:58 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 10.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 11.5
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-93565-4-FwjiGHtYDN@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-93565-4@http.gcc.gnu.org/bugzilla/>
References: <bug-93565-4@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
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D93565

--- Comment #29 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Looking back at this one, I (In reply to Wilco from comment #8)
> Here is a much simpler example:
>=20
> void f (int *p, int y)
> {
>   int a =3D y & 14;
>   *p =3D a | p[a];
> }
After r14-9692-g839bc42772ba7af66af3bd16efed4a69511312ae, we now get:
f:
.LFB0:
        .cfi_startproc
        and     w2, w1, 14
        mov     x1, x2
        ldr     w2, [x0, x2, lsl 2]
        orr     w1, w2, w1
        str     w1, [x0]
        ret
        .cfi_endproc

There is an extra move still but the duplicated and is gone. (with
-frename-registers added, the move is gone as REE is able to remove the zero
extend but then there is a life range conflict so can't remove the move too=
).

So maybe this should be closed as fixed for GCC 14 and the cost changes for=
 clz
reverted.

```
Trying 7 -> 9:
    7: r105:SI=3Dr115:SI&0xe
      REG_DEAD r115:SI
    9: r110:DI=3Dzero_extend(r105:SI)
Failed to match this instruction:
(parallel [
        (set (reg:DI 110 [ _1 ])
            (and:DI (subreg:DI (reg:SI 115) 0)
                (const_int 14 [0xe])))
        (set (reg/v:SI 105 [ a ])
            (and:SI (reg:SI 115)
                (const_int 14 [0xe])))
    ])
Failed to match this instruction:
(parallel [
        (set (reg:DI 110 [ _1 ])
            (and:DI (subreg:DI (reg:SI 115) 0)
                (const_int 14 [0xe])))
        (set (reg/v:SI 105 [ a ])
            (and:SI (reg:SI 115)
                (const_int 14 [0xe])))
    ])
Successfully matched this instruction:
(set (reg/v:SI 105 [ a ])
    (and:SI (reg:SI 115)
        (const_int 14 [0xe])))
Successfully matched this instruction:
(set (reg:DI 110 [ _1 ])
    (and:DI (subreg:DI (reg:SI 115) 0)
        (const_int 14 [0xe])))
allowing combination of insns 7 and 9
original costs 4 + 4 =3D 8
replacement costs 4 + 4 =3D 8
i2 didn't change, not doing this
```=