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 52C8F3858CDA; Fri,  6 Jan 2023 22:14:27 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 52C8F3858CDA
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1673043267;
	bh=bWrddnmgOawsQb+9/7Vjg94uOWW/FsoHsYDBDE7d63Q=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=RxHl8h5zCOouedsAnzT1DXHAXf97/R1C/AIMS2ZY2hNTGWnGRWV2401NDIjCWpw7x
	 kjmz1ZnmFCsfmzfhHvTIODzDMgnFP1RNqk3cz+awwRH1lAjqPTcV1UUSf6vGINzWPU
	 rNM9rleAlgMQi2oWhlGtaaoKPl9VPxcHtgTnCyhk=
From: "tkoenig at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/34678] Optimization generates incorrect code with
 -frounding-math option (#pragma STDC FENV_ACCESS not implemented)
Date: Fri, 06 Jan 2023 22:14:26 +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: 4.3.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: tkoenig at gcc dot gnu.org
X-Bugzilla-Status: NEW
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: blocked
Message-ID: <bug-34678-4-77gpguoZmu@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-34678-4@http.gcc.gnu.org/bugzilla/>
References: <bug-34678-4@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=3D34678

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|                            |105105

--- Comment #47 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Thomas Koenig from comment #46)
> Fortran gets this right:

... but only by accident. This test case shows that it doesn't:

$ cat y.f90
module y
  implicit none
  integer, parameter :: wp =3D selected_real_kind(15)
contains
  subroutine foo(a,b,c)
    use ieee_arithmetic
    real(kind=3Dwp), dimension(4), intent(out) :: a
    real(kind=3Dwp), intent(in) :: b, c
    type (ieee_round_type), dimension(4), parameter :: mode =3D &
         [ieee_nearest, ieee_to_zero, ieee_up, ieee_down]
    call ieee_set_rounding_mode (mode(1))
    a(1) =3D b + c
    call ieee_set_rounding_mode (mode(2))
    a(2) =3D b + c
    call ieee_set_rounding_mode (mode(3))
    a(3) =3D b + c
    call ieee_set_rounding_mode (mode(4))
    a(4) =3D b + c
  end subroutine foo
end module y

program main
  use y
  real(kind=3Dwp), dimension(4) :: a
  call foo(a, 0.1_wp, 0.2_wp)
  print *,a
end program main
$ gfortran -O  y.f90 && ./a.out
  0.30000000000000004       0.30000000000000004       0.30000000000000004=
=20=20=20=20=20=20
0.30000000000000004=20=20=20=20=20
$ gfortran y.f90 && ./a.out
  0.30000000000000004       0.29999999999999999       0.30000000000000004=
=20=20=20=20=20=20
0.29999999999999999


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105105
[Bug 105105] [Meta] Fortran IEEE support=