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 6BEF43858D28; Tue, 20 Jun 2023 16:34:05 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6BEF43858D28
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1687278845;
	bh=2XUJPjcg8P21NDGf1v5I1IvgPZKoAH/XljdTHyfq3ME=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=ELhMTrEAf6J6F4XcJz5nctmpfPILCWclvc43bQ0VaDUrduTUb8X3HRuuu9A8C5NCk
	 yAKhfYubE1zMytMidS+JhyOGtNpbkOkHli82j0KXKgQr6K1J+THs3ql9+I+enMpPqd
	 BIjimSPFW9gUCRgA756wzXx953xQoFXH4FyxNucI=
From: "theodort at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/109943] [13/14 Regression] Missed Dead Code
 Elimination when using __builtin_unreachable since r13-6834-g41ade3399bd
Date: Tue, 20 Jun 2023 16:34:05 +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: 14.0
X-Bugzilla-Keywords: missed-optimization
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: 13.2
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-109943-4-SaKJ5rOLq2@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109943-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109943-4@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=3D109943

--- Comment #2 from Theodoros Theodoridis <theodort at inf dot ethz.ch> ---
Not sure if it's useful but the following also started with the same commit=
:=20


https://godbolt.org/z/Tqha4K976

Given the following code:

void foo(void);
static int d, e, h;
static int *f =3D &e, *q;
static int **g =3D &f;
static long j, p;
static short k;
void __assert_fail() __attribute__((__noreturn__));
static short(a)(short b, short c) {
    if (!(((b) >=3D -90) && ((b) <=3D 0))) {
        __builtin_unreachable();
    }
    return c =3D=3D 0 || b =3D=3D 1 && c =3D=3D 1 ?: b % c;
}
static int **i();
static int l(int *m, long n) {
    j =3D 0 >=3D d;
    k =3D j - 34834;
    if (a(-n, k)) *g =3D m;
    if (f =3D=3D 0 || f =3D=3D &e)
        ;
    else
        __assert_fail();
    for (; h; ++h)
        ;
    return *m;
}
static int *o() {
    l(f, 90);
    g =3D i();
    if (f =3D=3D 0 || f =3D=3D &e)
        ;
    else
        foo();
    return &d;
}
static int **i() {
    a(p, h);
    return &q;
}
int main() { o(); }

gcc-trunk -O2 generates:

main:
        subq    $8, %rsp
        movq    f(%rip), %rax
        movq    g(%rip), %rdx
        movq    %rax, (%rdx)
        cmpq    $e, %rax
        je      .L7
        testq   %rax, %rax
        jne     .L2
.L7:
        movl    h(%rip), %edx
        testl   %edx, %edx
        je      .L5
        movl    $0, h(%rip)
.L5:
        movq    $q, g(%rip)
        cmpq    $e, %rax
        je      .L6
        call    foo
.L6:
        xorl    %eax, %eax
        addq    $8, %rsp
        ret
.L2:
        xorl    %eax, %eax
        call    __assert_fail

gcc-12.3.0 -O2 generates:

main:
        movq    f(%rip), %rax
        movq    g(%rip), %rdx
        movq    %rax, (%rdx)
        cmpq    $e, %rax
        je      .L6
        testq   %rax, %rax
        jne     .L2
.L6:
        movl    h(%rip), %edx
        testl   %edx, %edx
        je      .L5
        movl    $0, h(%rip)
.L5:
        movq    $q, g(%rip)
        xorl    %eax, %eax
        ret
.L2:
        pushq   %rax
        xorl    %eax, %eax
        call    __assert_fail=