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 0B1F7385829C; Fri, 15 Mar 2024 05:19:07 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0B1F7385829C
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1710479948;
	bh=wt86do3OzY8fGUjW1MRKvx3FMgegX/AcLH/md1a8zWM=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=oLyZe+Nq+QhBCJn9hJM6LDR4XJhDajvGF2p6+EeQ507epC1bFZFzEsSsN+rsozcmo
	 DuGaeRyAFdL2ZizmkdwmtrrRCrQSmHlv2Mb/ypl3W7C7uGOid4YyHF4Byhx/oib9X/
	 PfKpG0XMHA3KqAHbkVjUzAFOdOJ/v75NSrDj4cHA=
From: "eggert at cs dot ucla.edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/114347] wrong constant folding when casting __bf16
 to int
Date: Fri, 15 Mar 2024 05:19:07 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 13.2.1
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: eggert at cs dot ucla.edu
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: 
Message-ID: <bug-114347-4-tsosn2tyo7@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-114347-4@http.gcc.gnu.org/bugzilla/>
References: <bug-114347-4@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=3D114347

--- Comment #2 from Paul Eggert <eggert at cs dot ucla.edu> ---
(In reply to Andrew Pinski from comment #1)
> I am not so sure that 257.0bf16 gets rounded to 256.

It should get rounded to 256, since 257 has no exact representation in __bf=
16
and 256 is the closest representable value.

And GCC does this correctly in my experiments. If I compile this:

  __bf16 w =3D 256.0bf16;
  __bf16 x =3D 257.0bf16;

with "gcc -O2 -S", the assembly code says ".value 17280" for both constants=
.=