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 0863E39C000D; Thu, 22 Apr 2021 08:28:15 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0863E39C000D
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/100182] [8/9/10/11/12 Regression] Miscompilation of
 atomic_float/1.cc on i686
Date: Thu, 22 Apr 2021 08:28:14 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub 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: 8.5
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: cc
Message-ID: <bug-100182-4-dbkSN5BGVj@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-100182-4@http.gcc.gnu.org/bugzilla/>
References: <bug-100182-4@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: Thu, 22 Apr 2021 08:28:15 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100182

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at gcc dot gnu.org

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The 29_atomics/atomic_float/wait_notify.cc hangs that unfortunately cause
regtest hangs (the timeout stuff doesn't seem to work here) seems to be cau=
sed
by this too, at least if 0 && out those 8 peephole2s in sync.md the hang is
gone.

Vlad, can spill slots (MEMs with MEM_EXPR equal to get_spill_slot_decl (fal=
se))
be read in multiple instructions (one store multiple reads)?

Unfortunately the patterns do use peep2_reg_dead_p and so it isn't something
that can be done in the split2 pass (reload_completed && !epilogue_complete=
d).

Maybe emit the stores always and if those peephole2s ever trigger, schedule=
 an
extra RTL DSE pass after peephole2?
I'm not sure it is safe to emit the stores as normal DFmode stores though (=
at
least not in all the cases), because while one atomic read (the one seen in=
 the
peephole2) can be DFmode-ish, further atomic reads (the ones the peephole2
doesn't see) could be DImode-ish.

Uros, can you please have a look?  Thanks.=