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Re: c/8395: gcc 2.95.4 and 3.2 generate wrong code for double onintel
- From: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
- To: nobody at gcc dot gnu dot org
- Cc: gcc-prs at gcc dot gnu dot org,
- Date: 4 Nov 2002 17:06:10 -0000
- Subject: Re: c/8395: gcc 2.95.4 and 3.2 generate wrong code for double onintel
- Reply-to: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
The following reply was made to PR c/8395; it has been noted by GNATS.
From: "Joseph S. Myers" <jsm28@cam.ac.uk>
To: Marco Bernardo <bernardo@sti.uniurb.it>
Cc: Bruce Allen <ballen@gravity.phys.uwm.edu>, Bruce Allen <ballen@aei.mpg.de>,
<gcc-gnats@gcc.gnu.org>, <gcc-bugs@gcc.gnu.org>, <nobody@gcc.gnu.org>
Subject: Re: c/8395: gcc 2.95.4 and 3.2 generate wrong code for double on
intel
Date: Mon, 4 Nov 2002 17:02:43 +0000 (GMT)
On Mon, 4 Nov 2002, Marco Bernardo wrote:
> However, for a person doing research on the formal semantics of programming
> languages, it is difficult to accept that two differently compiled versions
> of the same sequential program return two different values for the same input.
> The compiler should not be free to alter the semantics of a sequential program,
> i.e. the program output for a given input! Some consistency should be kept.
You should read Norrish's thesis (link from the GCC readings page) which
gives a (imperfect) formal model in HOL of the semantics of a subset of
C90. There are many areas where the program output for a given input is
only partially constrained.
--
Joseph S. Myers
jsm28@cam.ac.uk