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 863423858C50; Fri, 21 Apr 2023 10:39:21 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 863423858C50
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1682073561;
	bh=I1Iije4XA08PAmxyJ9oi2xPJrmxUpdAKK7QjpcfcDH4=;
	h=From:To:Subject:Date:From;
	b=nmbRHVUkwtFm+OylkyNWRySrnsCJKOHqQO8tkSyYv3kNvOFFO3kaROLC3uHAx+939
	 fFN0g6KlE8vv6DFkyUsTC6Nj0P0p3XqvmbKdnGHLup1R00YJHEJMcosaFYVzTAtUkh
	 eIwROsvtivmyM4QfA2OGr7q4PamxLEJoSNuJeSM0=
From: "hector at marcansoft dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/109585] New: Carla/sord miscompiled with -O2 on ARM64
 (inlining issue)
Date: Fri, 21 Apr 2023 10:39:20 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: 12.1.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: hector at marcansoft dot com
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
 attachments.created
Message-ID: <bug-109585-4@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=3D109585

            Bug ID: 109585
           Summary: Carla/sord miscompiled with -O2 on ARM64 (inlining
                    issue)
           Product: gcc
           Version: 12.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hector at marcansoft dot com
  Target Milestone: ---

Created attachment 54900
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D54900&action=3Dedit
Manually annotated disassembly identifying the problem

GCC 12.1.0 miscompiles sord_free() with -O2 due to bad inlining on ARM64.
Reproducible on Compiler Explorer on 12.2 and also trunk.

https://godbolt.org/z/rvxP1oodh (includes full preprocessed input)

I've attached an annotated disassembly. The problem is that
zix_btree_iter_increment() and zix_btree_iter_is_end() are inlined together
into sord_free(), but the `i->stack[0].node =3D=3D NULL` check in
zix_btree_iter_is_end() somehow got hoisted before the `f->node =3D NULL;` =
in
zix_btree_iter_increment(), so the check fails when it pass (ending the loo=
p),
and then the loop body goes on to deref a NULL pointer.=