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 85D313858C33; Wed, 28 Jun 2023 10:21:15 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 85D313858C33
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1687947675;
	bh=aFTO9wgK+YVKSjU+/FXx5hZ58BOs+z6RJ6I342m+dFM=;
	h=From:To:Subject:Date:From;
	b=I6BA44LKQVjF38ZnUeEI80IxL6kwdzvRWfhwPO0F9tBhS3yIPaCEv7Qh8sXGZcHMO
	 drIWiyeOg27iu9eCckeMTInBPePD9A/XhTUQ0Rcs23AI7kf96bS78BcOreZRzlxMoW
	 vLgdlMVHYAE+cNV3VnrWxs/3izOIkQ62duKGERUY=
From: "theodort at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110450] New: [14 Regression] Dead Code
 Elimination Regression at -O2 since r14-261-g0ef3756adf0
Date: Wed, 28 Jun 2023 10:21:15 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: theodort at inf dot ethz.ch
X-Bugzilla-Status: UNCONFIRMED
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: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-110450-4@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=3D110450

            Bug ID: 110450
           Summary: [14 Regression] Dead Code Elimination Regression at
                    -O2 since r14-261-g0ef3756adf0
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: theodort at inf dot ethz.ch
  Target Milestone: ---

https://godbolt.org/z/KqcYxfevj

Given the following code:

void foo(void);
static int a =3D 1;
static int *b =3D &a, *c =3D &a;
static short d, e;
static char f =3D 11;
static char(g)(char h, int i) { return h << i; }
int main() {
    if (f) *c =3D g(0 >=3D a, 3);
    e =3D *c;
    d =3D e % f;
    if (d) {
        __builtin_unreachable();
    } else if (*b)
        foo();
    ;
}

gcc-trunk -O2 does not eliminate the call to foo:

main:
        movl    a(%rip), %eax
        xorl    %edx, %edx
        testl   %eax, %eax
        setle   %dl
        leal    0(,%rdx,8), %edx
        movl    %edx, a(%rip)
        jle     .L8
        xorl    %eax, %eax
        ret
.L8:
        pushq   %rax
        call    foo
        xorl    %eax, %eax
        popq    %rdx
        ret

gcc-13.1.0 -O2 eliminates the call to foo:

main:
        movl    a(%rip), %edx
        xorl    %eax, %eax
        testl   %edx, %edx
        setle   %al
        leal    0(,%rax,8), %eax
        movl    %eax, a(%rip)
        xorl    %eax, %eax
        ret

Bisects to r14-261-g0ef3756adf0=