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 5C2463939C0D; Wed, 28 Apr 2021 12:51:30 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5C2463939C0D
From: "vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/100232] [OpenMP][nvptx] Reduction fails with
 optimization and 'loop'/'for simd' but not with 'for'
Date: Wed, 28 Apr 2021 12:51:30 +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: openmp, wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: vries at gcc dot gnu.org
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: cc
Message-ID: <bug-100232-4-FmA8tKXk4D@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-100232-4@http.gcc.gnu.org/bugzilla/>
References: <bug-100232-4@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: Wed, 28 Apr 2021 12:51:30 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100232

Tom de Vries <vries at gcc dot gnu.org> changed:

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

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
In expand_GOMP_SIMT_XCHG_BFLY, we have a subreg target:
...
(gdb) call debug_rtx ( target )
(subreg/s/u:QI (reg:SI 40 [ _61 ]) 0)
...

During expand_insn, the operands are legitimized, and this changes the stat=
e of
the output operand to:
...
(gdb) call debug_rtx ( ops[0].value )
(reg:QI 57)
...

So the value is written to reg 57, but never actually copied back to reg 40.

Tentative fix:
...
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index dd7173126fb..28ae3ed167a 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -361,6 +361,8 @@ expand_GOMP_SIMT_XCHG_BFLY (internal_fn, gcall *stmt)
   create_input_operand (&ops[2], idx, SImode);
   gcc_assert (targetm.have_omp_simt_xchg_bfly ());
   expand_insn (targetm.code_for_omp_simt_xchg_bfly, 3, ops);
+  if (ops[0].value !=3D target)
+    emit_move_insn (target, ops[0].value);
 }

 /* Exchange between SIMT lanes according to given source lane index.  */
...=