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 1DA973833034; Wed,  2 Jun 2021 12:42:42 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1DA973833034
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/99122] [10 Regression] ICE in force_constant_size, at
 gimplify.c:733
Date: Wed, 02 Jun 2021 12:42:41 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: ipa
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: jamborm at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 10.4
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-99122-4-P4S9GSSDgR@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-99122-4@http.gcc.gnu.org/bugzilla/>
References: <bug-99122-4@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, 02 Jun 2021 12:42:42 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99122

--- Comment #34 from Richard Biener <rguenth at gcc dot gnu.org> ---
interestingly I see

  a.9_70 =3D .builtin_alloca_with_align (iftmp.8_1, 8);
  (*a.9_70) =3D inline22.get_zero (); [static-chain: &FRAME.20] [return slot
optimization]

so there's no WITH_SIZE_EXPR, but the return value ends up done by referenc=
e:

        leaq    -80(%rbp), %rdx
        movq    %rdx, %r10
        movq    %rax, %rdi
        call    inline22__get_zero.0
        movq    %rbx, %rsp
        movq    -8(%rbp), %rbx
        leave

so I wonder if omitting DECL_BY_REFERENCE is simply a bug?  I mean the
ABI of the callee must be aware and it seems CALL_EXPR_RETURN_SLOT_OPT
is set by gimplification.  IIRC CALL_EXPR_RETURN_SLOT_OPT also only means
we _may_ return by reference not that we must.

/* In a CALL_EXPR, means that it's safe to use the target of the call
   expansion as the return slot for a call that returns in memory.  */
#define CALL_EXPR_RETURN_SLOT_OPT(NODE) \
  (CALL_EXPR_CHECK (NODE)->base.private_flag)

But of course if we do not exercise the return slot opt then there definite=
ly
is a WITH_SIZE_EXPR missing.  Unless I'm missing somehting ...

The gimplifier code checks

              else if (TREE_CODE (*to_p) !=3D SSA_NAME
                      && (!is_gimple_variable (*to_p)
                          || needs_to_live_in_memory (*to_p)))
                /* Don't use the original target if it's already addressabl=
e;
                   if its address escapes, and the called function uses the
                   NRV optimization, a conforming program could see *to_p
                   change before the called function returns; see c++/19317.
                   When optimizing, the return_slot pass marks more functio=
ns
                   as safe after we have escape info.  */
                use_target =3D false;

so I wonder if you can modify the Ada testcase so that
CALL_EXPR_RETURN_SLOT_OPT is not set?=