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 553643858D34; Thu, 18 Jun 2020 20:10:03 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 553643858D34
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1592511003;
 bh=4d4YFtCnqSTMN6xwNnnws5W67lZr19PWUgqhLJ7ZXyM=;
 h=From:To:Subject:Date:In-Reply-To:References:From;
 b=ddA8vpKzhBp+BJNtghnq2QWPyQa6MowJOhPKoWZmkuzJ/2ZjUfqR9lVbBi9dSgWVa
 IjzQRX8tud/dOUqF4UqbKVEihhKFSKHacda6l1vzowILhAxGuEgZqWeyvyFdhhkt71
 2mivQF83SzIxRCRr5/YwoXgsIfmWVzpkAOgfkjHY=
From: "jason at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/95726] ICE with aarch64 __Float32x4_t as template argument
Date: Thu, 18 Jun 2020 20:10:03 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c++
X-Bugzilla-Version: 10.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jason at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: rsandifo at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-95726-4-LUAC6R6i3a@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-95726-4@http.gcc.gnu.org/bugzilla/>
References: <bug-95726-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Thu, 18 Jun 2020 20:10:03 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95726

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to rsandifo@gcc.gnu.org from comment #4)
> (In reply to Jakub Jelinek from comment #3)
> > But if they mangle differently, then structural_comptypes shouldn't tre=
at
> > them as same types.

Definitely.

> That certainly avoids the ICE, and makes GCC's behaviour consistent
> with Clang for things like:
>=20
>   typedef float vecf __attribute__((vector_size(16)));
>   vecf x;
>   float32x4_t &y =3D x;
>=20
> Previously we accepted this, with the struct_comptypes change
> we reject it (like Clang does).  But that might break existing
> code, so I'm not sure it would be backportable.

If necessary we could add a conversion between the pointer-to-vector types.

> I guess the question then is: what does TYPE_STRUCTURAL_EQUALITY_P
> mean for VECTOR_TYPEs in the context of structural_comptypes?

The same thing it means for any other type: setting TYPE_CANONICAL properly=
 is
too hard, so use structural_comptypes.

> And (if this is a different question) what case is that function's
> VECTOR_TYPE handling for?  I.e. when do we want to return true for
> a pair of VECTOR_TYPEs whose TYPE_MAIN_VARIANTs are different?

We want to return true if they should be considered the same type.

Generally, TYPE_MAIN_VARIANT isn't sufficient for checking type identity, a=
s it
only looks through variants of the outermost type:  If I have

typedef int myint;
typedef myint* myintptr;

taking TYPE_MAIN_VARIANT of myintptr gives myint*, not int*.  That's why
TYPE_CANONICAL was introduced, so we didn't need to do structural comparison
whenever we wanted to compare types.=