From owner-sc22wg5+sc22wg5-dom9=www.open-std.org@open-std.org Thu Feb 1 20:04:48 2024 Return-Path: X-Original-To: sc22wg5-dom9 Delivered-To: sc22wg5-dom9@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id 483BF356C60; Thu, 1 Feb 2024 20:04:48 +0100 (CET) Delivered-To: sc22wg5@open-std.org X-Greylist: delayed 1736 seconds by postgrey-1.34 at www5.open-std.org; Thu, 01 Feb 2024 20:04:47 CET Received: from troutmask.apl.washington.edu (troutmask.apl.washington.edu [128.95.76.21]) by www.open-std.org (Postfix) with ESMTP id B197C356C48 for ; Thu, 1 Feb 2024 20:04:47 +0100 (CET) Received: from troutmask.apl.washington.edu (localhost [127.0.0.1]) by troutmask.apl.washington.edu (8.17.1/8.17.1) with ESMTP id 411IZjrg004493; Thu, 1 Feb 2024 10:35:45 -0800 (PST) (envelope-from kargl@uw.edu) DKIM-Filter: OpenDKIM Filter v2.10.3 troutmask.apl.washington.edu 411IZjrg004493 Received: (from kargl@localhost) by troutmask.apl.washington.edu (8.17.1/8.17.1/Submit) id 411IZjGo004492; Thu, 1 Feb 2024 10:35:45 -0800 (PST) (envelope-from kargl@uw.edu) Date: Thu, 1 Feb 2024 10:35:45 -0800 From: "Steven G. Kargl" To: General J3 interest list Cc: WG5 , Jeff Hammond Subject: Re: [J3] [SC22WG5.6537] question about storage sequences and default kind modification Message-ID: Reply-To: kargl@uw.edu References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: Sender: owner-sc22wg5@open-std.org Precedence: bulk Jeff, Having dealt with many bugs reports about gfortran's -fdefault-*, -freal-*, and -finteger-* options, I'll suggest that you may not want to go down the route of supporting users redefining storage association.=20 Consider the following with gfortran on an AMD64 system, program foo real dr ! Default real double precision dd ! Default double precision real(4) sp ! gfortran kind=3D4 (single precision ) real(8) dp ! gfortran kind=3D8 (double precision)=20 real(10) xp ! gfortran kind=3D10 (Intel 80-bit extended DP)=20 real(16) qp ! gfortran kind=3D16 (quad precision) print '(A,*(1X,I0))', 'Default:', & & storage_size(dr), storage_size(dd) print '(A,*(1X,I0))', ' Kinds:', & & storage_size(sp), storage_size(dp), storage_size(xp), storage_size(qp) end program foo % gfortran13 -o z a.f90 && ./z Default: 32 64 Kinds: 32 64 128 128 % gfortran13 -o z -fdefault-real-8 a.f90 && ./z Default: 64 128 Kinds: 32 64 128 128 Default REAL is now 8 bytes and default DOUBLE PRECISION is 16 bytes. The entities declared via KIND=3D are unchanged. % gfortran13 -o z -freal-4-real-8 a.f90 && ./z Default: 64 64 Kinds: 64 64 128 128 All entities that map to a 4-byte real are promoted to an 8-byte real. --=20 steve On Thu, Feb 01, 2024 at 04:30:27PM +0000, Jeff Hammond via J3 wrote: > Bill has mentioned this to me before but I want to verify my understand o= f storage sequences. >=20 > If I have a compiler like Intel Fortran that offers many options to the s= ize of INTEGER to 2/4/8 bytes and REAL to 4/8/16 bytes, the only conforming= options set INTEGER and REAL to the same size and DOUBLE PRECISION to twic= e that, correct? >=20 > This is not intended to pick on Intel because most implementations have t= hese options, they just have the most as far as I can see. My goal is to b= ound the scope of the MPI ABI proposal by only bothering to support conform= ing uses of these options, or these plus the most widely used non-conformin= g use (-integer-size 8 -double-size 8). >=20 > Thanks, >=20 > Jeff >=20 > 19.5.3.2 Storage sequence >=20 > A storage sequence is a sequence of storage units. The size of a storage = sequence is the number of storage units in the storage sequence. A storage = unit is a character storage unit, a numeric storage unit, a file storage un= it (12.3.5), or an unspecified storage unit. The sizes of the numeric stora= ge unit, the character storage unit and the file storage unit are the value= s of constants in the ISO_FORTRAN_ENV intrinsic module (16.10.2). >=20 > In a storage association context >=20 > (1) a nonpointer scalar object that is default integer, default real, or = default logical occupies a single numeric storage unit, > (2) a nonpointer scalar object that is double precision real or default c= omplex occupies two contiguous numeric storage units, >=20 >=20 > $ ifort -help data >=20 > Data > ---- >=20 > -i{2|4|8} > set default KIND of integer and logical variables to 2, 4, or 8 > -integer-size > specifies the default size of integer and logical variables > size: 16, 32, 64 > -r{8|16} set default size of real to 8 or 16 bytes > -real-size > specify the size of REAL and COMPLEX declarations, constants, > functions, and intrinsics > size: 32, 64, 128 > -autodouble > same as -real-size 64 or -r8 > -double-size > defines the size of DOUBLE PRECISION and DOUBLE COMPLEX declara= tions, > constants, functions, and intrinsics > size: 64, 128 --=20 Steve